Classroom-Mode Based Interactive Whiteboard Collaboration System

Abstract

The objective of the present invention is to solve the aforementioned problems by providing a permission / mode-based collaboration structure at the classroom level, implementing collision-free real-time editing even in situations of network instability through STOMP broker + CRDT-based data synchronization, performing bandwidth optimization and high-quality rendering through stroke vector data transmission, enabling centralized management and reuse of class materials through a queue-based data conversion and distribution pipeline, and improving classroom operation efficiency through integration with administrative and IoT device control. Accordingly, a classroom-mode-based electronic whiteboard collaboration system according to one aspect of the present invention includes a teacher terminal (100), an electronic whiteboard terminal (200), a student terminal (300), an administrative office terminal (400), a message broker (500), a collaboration synchronizer (600), a data conversion server (700), and a security module (800). The message broker transmits vector path data containing stroke coordinates, pressure, and color information between the teacher terminal (100), the electronic whiteboard terminal (200), and the student terminal (300) with low latency through a pub / sub transmission structure based on the STOMP protocol. The collaboration synchronizer performs collision-free merging and synchronization of whiteboard data between terminals even when the network environment is unstable through a CRDT-based merging algorithm. The data conversion server converts uploaded files (PPTX, PDF, etc.) into images and distributes them as backgrounds to the classroom board via a CDN. The security module performs JWT-based authentication and AES-256 encryption to ensure the integrity and safety of all data transmissions.

Description

Technology Field

[0001] The present invention relates to a learning space management technology utilizing an educational electronic whiteboard and a linked terminal, and more specifically, to an electronic whiteboard collaboration system and a control method thereof that links a teacher's web, an electronic whiteboard app, and a student app on a classroom basis, and provides permission-based real-time collaboration and data synchronization such as focus mode and individual board mode. Background Technology

[0003] Recently, the educational environment has been changing rapidly in conjunction with digital transformation. In particular, in public education settings including elementary, middle, and high schools, the introduction of hardware infrastructure such as electronic whiteboards, smart pads, and high-speed networks is accelerating. Furthermore, due to institutional changes such as the one-device-per-student policy, the high school credit system, and the free semester system, the form of instruction is shifting from teacher-centered, one-way delivery classes to student-participatory and collaborative classes.

[0004] However, compared to such hardware-centric investments, the software infrastructure capable of effectively operating and utilizing them remains limited. Existing embedded software for electronic whiteboards has the following limitations.

[0006] 1) Device dependency

[0007] Since handwritten notes and class materials are stored only in the electronic whiteboard's internal storage, it is difficult to move between classrooms or retrieve the same materials on a different electronic whiteboard.

[0008] Due to the lack of a central server-based data management function, even the same class materials must be re-uploaded or reconfigured if the classroom or device changes.

[0010] 2) Unidirectional communication structure

[0011] Most electronic whiteboard software is limited to a system where students view handwritten notes created by the teacher, and it lacks features that allow students to share their individually written content with the teacher in real time, or conversely, enable the teacher to simultaneously monitor each student's progress. As a result, student participation rates are low, and it is difficult to diagnose individual learning and provide customized feedback.

[0013] 3) Limitations of real-time collaboration during network instability

[0014] Transmission via screen mirroring is vulnerable to network latency and interruptions, making stable collaboration difficult in wireless or large-scale connection environments. Additionally, issues arise where content created while offline is lost or overwritten upon reconnection.

[0016] 4) Lack of flexibility in content processing

[0017] The functionality to convert and distribute class materials in various formats, such as PDF, PPTX, and images, is inadequate. Furthermore, since the conversion and distribution process is manual and relies on individual devices, preparation time before class is prolonged, and the usability of the materials is reduced.

[0019] 5) Limitations on integration with external systems

[0020] It is difficult to automate and optimize the learning environment because it is not linked to IoT devices (lighting, heating and cooling, blinds, etc.) or school administrative systems within the classroom.

[0021] In addition, there is a lack of functionality to automatically control the classroom environment according to the class mode, or to centrally monitor and control the device status from the administrative terminal.

[0023] These limitations pose a significant constraint on implementing real-time collaboration, personalized learning, and online-offline continuity in educational settings. In particular, despite the fact that hybrid classes combining remote and in-person instruction have become commonplace since the COVID-19 pandemic, most current electronic whiteboards and instructional support software do not adequately provide features to seamlessly connect the two environments.

[0024] Ultimately, there is a need for a new type of electronic whiteboard-linked collaboration system that responds to hardware advancements and policy changes by enabling simultaneous access from various devices, stable data synchronization even in unstable network environments, control of roles and permissions at the classroom level, and management and reuse of materials based on a central server and cloud. Prior art literature

[0026] Published Patent 10-2025-0116975 (2025.08.04), Artificial Intelligence (AI)-based electronic whiteboard system (An electronic board system) The problem to be solved

[0027] The objective of the present invention is to solve the aforementioned problems by providing a permission / mode-based collaboration structure at the classroom level, implementing collision-free real-time editing even in situations of network instability through STOMP broker + CRDT-based data synchronization, performing bandwidth optimization and high-quality rendering through stroke vector data transmission, enabling centralized management and reuse of class materials through a queue-based data conversion and distribution pipeline, and improving classroom operation efficiency through integration with administrative and IoT device control. means of solving the problem

[0029] A classroom-mode-based electronic whiteboard collaboration system according to one aspect of the present invention includes a teacher terminal (100), an electronic whiteboard terminal (200), a student terminal (300), and an administrative office terminal (400), a message broker (500), a collaboration synchronizer (600), a data conversion server (700), and a security module (800). The message broker transmits vector path data containing stroke coordinates, pressure, and color information between the teacher terminal (100), the electronic whiteboard terminal (200), and the student terminal (300) with low latency through a pub / sub transmission structure based on the STOMP protocol. The collaboration synchronizer performs collision-free merging and synchronization of whiteboard data between terminals even when the network environment is unstable through a CRDT-based merging algorithm. The data conversion server converts uploaded files (PPTX, PDF, etc.) into images and distributes them as backgrounds to the classroom board via a CDN. The security module performs JWT-based authentication and AES-256 encryption to ensure the integrity and safety of all data transmissions.

[0030] At this time, the collaboration synchronizer stores all class activity change history, such as handwriting, editing, and mode switching, in the local storage of each terminal in the event of a network failure in the form of a log containing chronological order and version information; upon reconnection, it automatically identifies conflicting items by comparing the stored log with the current server state, generates an integrated state reflecting the order and priority of changes using a CRDT merging algorithm, and propagates the merging result to all connected terminals simultaneously, thereby maintaining the continuity of class progress and data consistency even in an unstable network environment.

[0031] In addition, the data conversion server registers the uploaded data in a conversion queue and performs the conversion in a parallel or sequential processing mode, automatically applies the resolution, ratio, and compression rate optimized according to the file format during the conversion process, and when uploaded to the CDN server after the conversion is completed, it includes the metadata of the data (at least one of subject name, session number, author, and version) and links it with the class room metadata information, and the terminals participating in the class room receive the data from the CDN in a streaming manner and can immediately apply it as a board background or supplementary material.

[0032] In addition, the administrative office terminal automatically controls the operating status of IoT devices in the classroom (at least one of lighting, motorized blinds, heating and cooling units, and electronic whiteboard power) based on class timetables, mode switching events, and teacher / student account information; automatically turns on the power of necessary devices at the start of class and turns off the power at the end; performs environment settings appropriate to the situation, such as changing the illuminance and color temperature of the lighting in focus mode and controlling individual seat lighting in individual mode when switching modes; and stores power consumption and environment setting history in a database for use in analysis and report generation.

[0033] In addition, the message broker collects handwriting coordinate and pressure data input from the terminal in real time, converts them into an SVG or similar vector format, and compresses the vector data into a binary form after undergoing preprocessing steps such as linear interpolation, pressure curve correction, and color conversion. During transmission, an incremental transmission method is applied to retransmit only the lost parts in the event of packet-unit transmission failure, thereby minimizing network load. The receiving terminal then restores the vector data and renders it according to the screen resolution or zoom level, enabling high-quality handwriting reproduction with relatively lower bandwidth compared to screen streaming. Effects of the invention

[0035] The classroom-mode-based electronic whiteboard collaboration system according to the present invention can achieve new and significant effects, such as improved learning immersion through switching between focus mode / individual mode and permission control, seamless collaborative handwriting even on unstable networks, bandwidth reduction of more than 90% compared to screen streaming, ensuring data continuity between classroom movement and remote classes, and integrated learning space management linked to administrative office and facility control. Brief explanation of the drawing

[0037] FIG. 1 is a configuration diagram of a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention. FIG. 2 is a flowchart of a classroom mode switching scenario (focus / individual / group) in a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention. FIG. 3 is a flowchart of stroke vector data generation, transmission, and restoration in a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention. FIG. 4 is a flowchart of a data conversion and distribution queue pipeline structure in a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention. FIG. 5 is a flowchart for local log storage and reconnection merging processing in the event of a network failure in a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention. Specific details for implementing the invention

[0038] In order to clarify the features and advantages of the means for solving the problem of the present invention, the present invention will be described in more detail with reference to specific embodiments of the present invention illustrated in the attached drawings.

[0039] However, detailed descriptions of known functions or configurations that may obscure the essence of the invention are omitted in the following description and the attached drawings. Additionally, it should be noted that identical components throughout the drawings are indicated by the same reference numerals whenever possible.

[0040] Terms and words used in the following description and drawings should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of terms to best describe his invention. Accordingly, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the invention and do not represent all aspects of the technical spirit of the invention; therefore, it should be understood that various equivalents and modifications capable of replacing them may exist at the time of filing this application.

[0041] Furthermore, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0042] Furthermore, terms including ordinal numbers, such as first, second, etc., are used to describe various components and are used solely for the purpose of distinguishing one component from another, and are not used to limit said components. For example, without departing from the scope of the present invention, the second component may be named the first component, and similarly, the first component may be named the second component.

[0043] Furthermore, the terms used in this specification are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. Additionally, terms such as “comprising” or “having” described in this specification are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0044] Additionally, terms such as "part," "unit," and "module" as described in the specification refer to a unit that processes at least one function or operation, which may be implemented in hardware, software, or a combination of hardware and software. Furthermore, "one (a or an)," "one," "the," and similar related terms may be used in the context describing the invention (particularly in the context of the following claims) in a sense that includes both singular and plural forms, unless otherwise indicated in the specification or clearly contradicted by the context.

[0045] In addition, the term '~module' used in the embodiments of the present invention refers to a software component, and the '~module' performs certain roles. As an example, the '~module' includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, segments of program code, drivers, data, databases, data structures, tables, arrays, and variables. Furthermore, the functions provided within the components and '~modules' may be combined into a smaller number of components and '~modules' or further separated into additional components and '~modules'.

[0046] In various examples of the present disclosure, " / " and "," should be interpreted as indicating "and / or." For example, "A / B" may mean "A and / or B." Furthermore, "A, B" may mean "A and / or B." Furthermore, "A / B / C" may mean "at least one of A, B and / or C." Furthermore, "A, B, C" may mean "at least one of A, B and / or C."

[0047] In various examples of the present disclosure, "or" should be interpreted as indicating "and / or". For example, "A or B" may include "only A", "only B", and / or "both A and B". In other words, "or" should be interpreted as indicating "additionally or alternatively".

[0048] In addition to the terms described above, specific terms used in the following description are provided to aid in understanding the present invention, and the use of such specific terms may be modified in other forms without departing from the technical spirit of the present invention.

[0049] In addition, embodiments within the scope of the present invention include a computer-readable medium having or transmitting computer-executable instructions or data structures stored on a computer-readable medium. Such a computer-readable medium may be any available medium accessible by a general-purpose or special-purpose computer system. For example, such a computer-readable medium may include, but is not limited to, physical storage media such as RAM, ROM, EPROM, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, or any other medium accessible by a general-purpose or special-purpose computer system that can be used to store or transmit certain program code means in the form of computer-executable instructions, computer-readable instructions or data structures.

[0050] In addition, the present invention may be implemented in a network computing environment having various types of computer system configurations, including personal computers, laptop computers, handheld devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile phones, PDAs, pagers, etc. The present invention may also be implemented in a distributed system environment in which both local and remote computer systems linked via a network via a wired data link, a wireless data link, or a combination of wired and wireless data links perform tasks. In a distributed system environment, program modules may be located in local and remote memory storage devices.

[0051] Furthermore, it will be understood that each block of the process flow diagrams and combinations of the flow diagrams can be executed by computer program instructions. Since these computer program instructions can be loaded into the processor of a general-purpose computer, a specialized computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in the flow diagram block(s). Since these computer program instructions can also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in such computer-available or computer-readable memory can also produce a manufactured item containing instruction means to perform the function described in the flow diagram block(s). Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that perform a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer can also provide steps for executing the functions described in the flowchart block(s).

[0052] Additionally, each block may represent a module, segment, or part of code containing one or more executable instructions for executing a specified logical function(s). It should also be noted that in some alternative execution examples, the functions mentioned in the blocks may occur out of order. For instance, two blocks described in succession may actually be executed substantially simultaneously, or the blocks may be executed in reverse order according to their corresponding functions.

[0053] In describing the embodiments of the present disclosure in detail, the focus will be on examples of specific systems, but the main point claimed in this specification is applicable to other communication systems and services having a similar technical background without significantly departing from the scope disclosed in this specification, and this will be possible at the judgment of a person skilled in the art.

[0054] Hereinafter, a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention will be described. FIG. 1 is a configuration diagram of a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention, FIG. 2 is a flowchart of a classroom mode switching scenario (focus / individual / group) in a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention, FIG. 3 is a flowchart of stroke vector data generation, transmission, and restoration in a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention, FIG. 4 is a flowchart of a data conversion and distribution queue pipeline structure in a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention, and FIG. 5 is a flowchart of local log storage and reconnection merging processing in the event of a network failure in a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention.

[0055] Referring to the drawings, a classroom-mode based electronic whiteboard collaboration system according to one embodiment of the present invention is composed of a teacher terminal (100), an electronic whiteboard terminal (200), a student terminal (300), an administrative office terminal (400), a message broker (500), a collaboration synchronizer (600), a data conversion server (700), a security module (800), etc., and each component can be implemented in hardware or software.

[0057] 1. Overall System Architecture (See Fig. 1)

[0058] The present invention is broadly divided into a terminal layer, a server / broker layer, and a support service layer.

[0060] (1) Teacher's terminal (100)

[0061] The main control terminal used by the teacher. It is typically implemented as a laptop, desktop, or tablet, and accesses the system via a web browser or a dedicated application.

[0062] The teacher terminal (100) performs the roles of ① creating and managing class rooms, ② controlling mode switching (focus, individual, group), ③ granting and revoking handwriting permissions, ④ uploading and distributing materials, and ⑤ real-time monitoring and feedback of student boards.

[0063] At this time, the teacher terminal (100) may be composed of general PC or tablet hardware, a network module (Wi-Fi / LAN), a microphone and camera (optional), and in terms of software, may include an HTML5-based web application or native app, a STOMP / WebSocket client, a UI rendering engine, and a permission control module.

[0065] (2) Electronic whiteboard terminal (200)

[0066] It refers to a device that visually displays the handwriting of a teacher or student based on a large touch display. The electronic whiteboard terminal (200) performs the functions of ① displaying the teacher's handwriting and materials on a large screen, ② selectively displaying the student board when necessary, and ③ changing the display method according to the classroom mode.

[0067] At this time, the electronic whiteboard terminal (200) may include a large touchscreen panel, an embedded PC or Android board, a network module, and a graphics processor in terms of hardware, and may be composed of a dedicated app, a STOMP client, a handwriting rendering module, and a viewer UI in terms of software.

[0069] (3) Student terminal (300)

[0070] A terminal that students use for individual note-taking and participation. Various devices such as tablets, laptops, and smartphones can be used. The student terminal (300) performs ① receiving teacher notes, ② creating and editing individual boards, ③ viewing and submitting assignments and materials, and ④ participating in group mode.

[0071] At this time, the student terminal (300) may include a touch input support device and a network module in terms of hardware, and may include a dedicated app or web application, a STOMP / WebSocket client, and a vector rendering engine in terms of software.

[0073] (4) Administrative office terminal (400)

[0074] It refers to a terminal for administrators that manages teachers, classes, equipment, and facilities, and performs the roles of ① account registration and deletion, ② class schedule management, ③ equipment status monitoring, and ④ IoT-linked control (lighting, heating and cooling, blinds, etc.).

[0075] In terms of hardware, it can be configured as a standard PC or tablet, and in terms of software, it can include a management console UI and REST API integration modules.

[0077] (5) Message broker (500)

[0078] It is a server module that relays data between terminals and performs the tasks of ① processing pub / sub messaging based on the STOMP protocol, ② delivering events for real-time whiteboarding, mode switching, and permission changes, and ③ managing connection sessions. In terms of hardware, it can be configured as a cloud server or an on-premises server, and in terms of software, it may include Spring Boot, RabbitMQ / ActiveMQ, and a session management module.

[0080] (6) Collaboration Synchronizer (600)

[0081] It is a module that merges and synchronizes editing data from multiple users. The collaboration synchronizer (600) performs the roles of ① merging based on CRDT (Conflict-free Replicated Data Type), ② merging upon offline log storage and reconnection, and ③ managing change history versions. In terms of hardware, it may be configured as a local module within a server or terminal, and in terms of software, it may include a CRDT library such as YJS and a synchronization algorithm.

[0083] (7) Data conversion server (700)

[0084] It refers to a server that converts and distributes uploaded class materials into images that can be used in the classroom. The data conversion server (700) performs the roles of ① converting PPTX / PDF files into images such as PNG / JPEG, ② distributing the converted materials to a CDN, and ③ load balancing through a conversion queue. In terms of hardware, the data conversion server (700) may be configured as a CPU / GPU server for conversion processing, and in terms of software, it may include LibreOffice, ImageMagick, and a file queue processing module.

[0086] (8) Security module (800)

[0087] As a module responsible for the authentication and encryption of the entire system, it performs the roles of ① JWT (Json Web Token)-based authentication, ② AES-256 data encryption, and ③ access permission verification; on the hardware side, it can be configured as a server or a local security chip (optional), and on the software side, it may include an encryption library and certificate management.

[0088] Hereinafter, a classroom mode switching scenario (focus / individual / group) in a classroom-mode-based electronic whiteboard collaboration system according to one embodiment of the present invention will be described in more detail.

[0089] Referring to Fig. 2, in the classroom mode switching scenario, the classroom can be switched to three main modes.

[0091] 1) Focus Mode

[0092] Only handwriting and data from the teacher's terminal (100) are transmitted to all terminals, and student handwriting is blocked. It is used for presentations, lecture explanations, quiz explanations, etc.

[0094] 2) Individual Mode

[0095] An independent board is created on each student terminal (300) to enable individual learning. The teacher monitors the student's work via a grid view on the teacher terminal (100) and provides feedback when necessary.

[0097] 3) Group Mode

[0098] Joint editing between specific student groups is possible, and board changes within the group are immediately merged through the collaboration synchronizer (600). Suitable for discussions and team projects.

[0100] That is, the classroom of the present invention can be switched between three modes: concentration mode, individual mode, and group mode. Each mode switch is initiated by the teacher terminal (100) and propagated in real time to the electronic whiteboard terminal (200) and student terminal (300) through the message broker (500), and the collaboration synchronizer (600) maintains the board state consistently.

[0101] In focus mode, the teacher has exclusive writing rights and the student is set to read-only status, and the teacher's board is displayed identically on both the electronic whiteboard terminal (200) and the student terminal (300).

[0102] In individual mode, an independent board is created on each student terminal (300) and editing is allowed, and on the teacher terminal (100), all students' boards are monitored in real time in a grid format and a specific board can be selected and annotated.

[0103] In group mode, a group-specific collaborative editing board designated by the teacher is created, and only students in that group can write on the board, and changes are merged in real time through the collaboration synchronizer (600).

[0104] Mode switching can be triggered by teacher UI operations, preset timers, class scripts, or voice commands, and is performed securely by checking the completion of saving and network status during the transition process. Additionally, a rollback function is provided to restore the state of the previous mode from a snapshot in the event of an error during the transition, and permission settings are managed using bit flags at the user role, mode, and board levels.

[0106] Hereinafter, the stroke vector data generation, transmission, and restoration flow in a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention will be described in more detail.

[0107] As shown in Fig. 3, when touch or pen input occurs on the terminal, data such as coordinates (x, y), pressure, color, and thickness is extracted. The data is converted into a vector path in SVG format, and a compression algorithm is applied if necessary.

[0108] The message broker (500) transmits the data to the subscriber terminal. The receiving terminal releases and restores the data and displays it on the screen through a rendering engine.

[0109] That is, the handwriting data transmission of the present invention is performed by sampling input data such as coordinates, pressure, color, and thickness in real time, converting it into a vector path, compressing it into a binary form, and then transmitting it through a message broker (500).

[0110] In the input stage, events are collected from a pen or touch sensor at 60120Hz per second, coordinates and pressure are normalized to the 01 range, and colors are converted to RGBA values. When generating a path, the number of points is reduced using the Larmor-Douglas-Picker algorithm or Bézier curve fitting to minimize data size, and the packet size is reduced by applying delta encoding, which records only the change value relative to the previous coordinate.

[0111] The transmission packet includes the Board ID, Layer ID, timestamp, and CRC value, and is encrypted using AES-256 prior to transmission. On the receiving end, after decryption and integrity verification, the delta data is inversely transformed to restore the coordinate sequence, smoothly reconstructed using Bézier curves or splines, and then rendered according to the resolution and scale of each terminal.

[0112] In the event of packet loss, an incremental retransmission method is applied to retransmit only the affected range, and layer management and eraser functions are supported during the rendering process. This enables high-resolution handwriting reproduction while significantly reducing bandwidth usage compared to screen streaming.

[0114] Hereinafter, the data conversion and distribution queue pipeline structure in a classroom-mode-based electronic whiteboard collaboration system according to one embodiment of the present invention will be described in more detail.

[0115] As illustrated in FIG. 4, the data conversion and distribution pipeline uploads data (PPTX, PDF, etc.) from a teacher terminal (100). At this time, the data conversion server (700) registers the task in the conversion queue. The conversion server converts the file into a PNG image, uploads it to a CDN, and applies the converted image as a background to the classroom board.

[0116] That is, referring to FIG. 4, the data conversion and distribution process of the present invention consists of the procedure of registering a file uploaded from a teacher terminal (100) in the conversion queue of a data conversion server (700), and a conversion worker converting it into an image and distributing it to a classroom via a CDN.

[0117] During the upload stage, a thumbnail is generated after checking the file format, size, and security. When registered in the conversion queue, metadata such as subject name, lesson number, teacher information, output resolution, and page range is saved. The conversion worker converts PPTX to PDF using LibreOffice or Unoconv, and then converts the PDF into PNG images using ImageMagick.

[0118] Once the conversion is complete, assign a page number and access permission tag to each image, upload it to a CDN server to generate version control and cache keys.

[0119] In the classroom, the material can be designated as a board background or supplementary material, and pre-loading minimizes delays during conversion. Automatic retries are performed in the event of a conversion failure, and all conversion and distribution history is saved in the audit log.

[0120] Optionally, a text search function can be provided via OCR, or a function that displays a low-resolution preview first and then replaces it with a high-resolution image can also be implemented.

[0122] Hereinafter, the local log storage and reconnection merging process in the event of a network failure in a classroom-mode-based electronic whiteboard collaboration system according to an embodiment of the present invention will be described in more detail.

[0123] As illustrated in FIG. 5, in the event of a network failure, the collaboration synchronizer (600) stores all change history in a log format in a local storage. Upon reconnection, the stored log and the current server state are compared and integrated using a CRDT merging algorithm to reflect the changes without conflict. As a result, all terminals maintain the latest state.

[0124] That is, the present invention provides a function to store local logs at each terminal so that work content is not lost even in the event of a network failure, and to merge them using a CRDT algorithm by a collaboration synchronizer (600) upon reconnection. In an offline state, all operations such as board editing, handwriting, and object insertion / deletion are recorded in a local storage along with timestamps and causal relationship information.

[0125] Data is stored using IndexedDB in a web environment and SQLite or a file system in a native app. Upon reconnection, the terminal uploads only operations from the stored logs that have not been reflected on the server, and the collaboration synchronizer (600) compares this with the current server state to check for conflicts and merges them according to a predefined policy, such as teacher priority or latest timestamp priority.

[0126] The merged final state is distributed to all connected terminals via incremental transmission to prevent unnecessary bandwidth consumption. Log files are limited in size, and older records are merged into snapshots and deleted; this design ensures efficient use of battery and storage space even during prolonged offline periods. This structure guarantees class continuity even in unstable network conditions, such as Wi-Fi congestion, mobile classes, or remote environments.

[0127] As explained above, although this specification contains details of a number of specific embodiments, these should not be understood as limiting the scope of any invention or claimables, but rather as descriptions of features that may be specific to a particular embodiment of a particular invention. In the context of individual embodiments, specific features described in this specification may be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any appropriate sub-combination. Furthermore, while features may operate in a specific combination and be described as initially claimed, one or more features from the claimed combination may be excluded from the combination in some cases, and the claimed combination may be changed to a sub-combination or a variation of the sub-combination.

[0128] Likewise, although operations are depicted in the drawings in a specific order, this should not be understood as requiring that such operations be performed in that specific or sequential order depicted to obtain a desirable result, or that all depicted operations must be performed. In certain cases, multitasking and parallel processing may be advantageous. Furthermore, the separation of the various system components of the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together into a single software product or packaged into multiple software products.

[0129] Specific embodiments of the subject matter described herein have been described. Other embodiments fall within the scope of the following claims. For example, the operations cited in the claims may be performed in different orders and still achieve desirable results. As an example, the process illustrated in the accompanying drawings does not necessarily require the specific illustrated order or sequential order to obtain desirable results. In specific embodiments, multitasking and parallel processing may be advantageous.

[0130] The description provided herein presents the best mode of the invention and offers examples to explain the invention and to enable a person skilled in the art to manufacture and use the invention. The specification thus written is not intended to limit the invention to the specific terms presented. Accordingly, although the invention has been described in detail with reference to the examples above, a person skilled in the art can make modifications, changes, and variations to these examples without departing from the scope of the invention.

[0131] Therefore, it is obvious that the scope of the present invention should not be determined by the described embodiments but by the claims. Explanation of the symbols

[0133] 100: Teacher's terminal 200: Electronic whiteboard terminal 300: Student Terminal 400: Administrative Office Terminal 500: Message broker 600: Collaboration Synchronizer 700: Data conversion server 800: Security Module

Claims

Claim 1 In a classroom-mode-based electronic whiteboard collaboration system comprising a teacher terminal (100), an electronic whiteboard terminal (200), a student terminal (300), an administrative office terminal (400), a message broker (500), a collaboration synchronizer (600), a data conversion server (700), and a security module (800), the teacher terminal (100) creates and manages a classroom, controls the switching of the classroom to one of a focus mode, an individual mode, and a group mode, grants or revokes handwriting rights according to the mode switching, and monitors and provides feedback on the student board in real time, and the message broker (500) transmits vector path data including stroke coordinates, pressure, and color information between the teacher terminal (100), the electronic whiteboard terminal (200), and the student terminal (300) with low latency through a pub / sub transmission structure based on the STOMP protocol, and also propagates mode switching events and permission change events initiated by the teacher terminal (100) to the electronic whiteboard terminal (200) and the student terminal (300) in real time, and the collaboration The synchronizer (600) performs collision-free merging and synchronization of whiteboard data between terminals even when the network environment is unstable through a CRDT-based merging algorithm, and maintains a consistent board state when switching modes, and in the intensive mode, only the handwriting and materials of the teacher terminal (100) are transmitted to the electronic whiteboard terminal (200) and the student terminal (300), and the student terminal (300) is set to a read-only state, and the board of the teacher terminal (100) is displayed identically on the electronic whiteboard terminal (200) and the student terminal (300), and in the individual mode, an independent board is created for each student terminal (300) and editing is allowed, and the teacher terminal (100) can monitor all students' boards in a grid form in real time and select a specific board to annotate, and in the group mode, a group-specific joint editing board designated by the teacher terminal (100) is created, and only the student terminal (300) belonging to the group can write on the joint editing board.A classroom-mode-based electronic whiteboard collaboration system characterized by the fact that changes to the joint editing board are merged in real time through the collaboration synchronizer (600), the mode switching is triggered by the teacher's UI operation, a preset timer, a class script, or a voice command, the completion of saving and network status are checked during the switching process, and if an error occurs during the switching, a rollback function is performed to restore the state of the previous mode to a snapshot, permission settings are managed by bit flags at the level of user roles, modes, and boards, the data conversion server (700) converts uploaded files (PPTX, PDF, etc.) into images and distributes them as backgrounds to the classroom board via a CDN, and the security module (800) performs JWT-based authentication and AES-256 encryption to ensure the integrity and safety of all data transmissions. Claim 2 A classroom-mode-based electronic whiteboard collaboration system according to claim 1, wherein the collaboration synchronizer stores all class activity change history, such as handwriting, editing, and mode switching, in a log format including chronological order and version information in the local storage of each terminal in the event of a network failure, automatically identifies conflicting items by comparing the stored log with the current server state upon reconnection, generates an integrated state reflecting the order and priority of changes by a CRDT merging algorithm, and simultaneously propagates the merging result to all connected terminals to maintain the continuity of class progress and data consistency even in an unstable network environment. Claim 3 A classroom-mode-based electronic whiteboard collaboration system according to claim 1, wherein the data conversion server registers uploaded data in a conversion queue to perform conversion work in a parallel or sequential processing mode, automatically applies an optimized resolution, ratio, and compression rate according to the file format during the conversion process, and when uploading to a CDN server after the conversion is completed, includes metadata of the data (at least one of subject name, lesson number, author, and version) and links with classroom metadata information, and the classroom participating terminal can receive the data from the CDN in a streaming manner and immediately apply it as a board background or supplementary material. Claim 4 A classroom-mode-based electronic whiteboard collaboration system according to claim 1, wherein the administrative office terminal automatically controls the operating status of IoT devices in the classroom (at least one of lighting, motorized blinds, heating and cooling units, and electronic whiteboard power) based on class timetables, mode switching events, and teacher / student account information, automatically turns on the power of devices required at the start of class and turns off the power at the end of class, performs environment settings appropriate to the situation such as changing the illuminance and color temperature of the lighting in concentration mode and controlling the lighting of individual seats in individual mode when switching modes, and stores power consumption and environment setting history in a database so that they can be utilized for analysis and report generation. Claim 5 A classroom-mode-based electronic whiteboard collaboration system according to claim 1, wherein the message broker collects handwriting coordinate and pressure data input from a terminal in real time, converts them into an SVG or similar vector format, the vector data is compressed into a binary form after undergoing preprocessing processes such as linear interpolation, pressure curve correction, and color conversion, minimizes network load by applying an incremental transmission method that retransmits only the lost parts in the event of packet-unit transmission failure during transmission, and the receiving terminal restores the vector data and renders it according to the screen resolution or zoom ratio, thereby enabling high-quality handwriting reproduction with a relatively low bandwidth compared to screen streaming.

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