Upper air environment gas measurement device for radio-sonde and measurement method thereof
Patent Information
- Application Number
- KR1020250024403
- Authority / Receiving Office
- KR · KR
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2026-09-01
Smart Images
Figure PAT00001_ABST
Abstract
Description
Technology Field
[0001] The present invention relates to a gas measuring device for a radiosonde, and more specifically, to an upper-air atmosphere environmental gas measuring device for a radiosonde that can be manufactured in a small, lightweight, and low-cost manner, and a method for measuring the same. Background Technology
[0002] To monitor environmental gases such as nitrogen dioxide (NO2) and ozone (O₃), measurements were taken periodically using aircraft at low altitudes below 10 km. In addition, measuring ozone in the high-altitude stratosphere requires specialized equipment that is expensive, complex, and not accessible for routine or widespread use.
[0003] Because these conventional measurement systems are bulky and expensive, they often required dedicated payloads for research aircraft, high-altitude balloons, or satellite missions. For example, in the case of upper-air atmosphere environmental gas measurement technology, the equipment used for Differential Optical Absorption Spectroscopy (DOAS) offers high sensitivity but costs over $50,000 and requires significant power and data processing capabilities.
[0004] Furthermore, while ozone sensors utilizing electrochemical concentration cells (ECCs) are used in some radiosondes, they require regular calibration and have a very limited capacity for simultaneously measuring multiple gases. Additionally, they have disadvantages such as high cost, heavy weight, and a complex non-positive pretreatment process. Nevertheless, they remain the most widely used method in the field.
[0005] Furthermore, while Cavity Ring-Down Spectroscopy (CRDS) is a state-of-the-art technology for gas analysis, it is a very expensive piece of equipment exceeding $100,000 and is used only in laboratories or high-budget field research projects.
[0006] Although satellite-based instruments (Tropospheric Monitoring Instrument, TROPOMI) are applicable globally, they have the disadvantages of high deployment costs, lack of access to regional or local research, and insufficient fine vertical resolution required for atmospheric profiling.
[0007] As such, reliance on conventional, expensive, and resource-intensive equipment creates limitations that prevent the frequent performance of high-resolution atmospheric gas measurements in developing countries or in scenarios requiring rapid deployment and cost-effectiveness. These limitations hinder comprehensive monitoring of air pollutants and impede the ability to address critical issues related to air quality, climate change, and ozone depletion. Prior art literature
[0008] Republic of Korea Patent Registration No. 10-2507977 (Method and system related to a radiosonde) The problem to be solved
[0009] Accordingly, the present invention has been devised to solve the above-mentioned problems, and the objective of the present invention is to provide an upper-air atmosphere environmental gas measuring device for a radiosonde and a method for measuring the same, which not only integrates an advanced gas sensor but is also manufactured to be compact and inexpensive for use in a radiosonde.
[0010] However, the technical problems to be solved by the present invention are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem
[0011] To achieve the above technical objectives, in a high-altitude atmospheric environmental gas measuring device (100) for a radiosonde (300), the device comprises: an insulating pack having an internal space (160); an air intake port (170) having one end exposed to the outside of the insulating pack to allow external air to flow in, and the other end extending to the internal space (160); a heater (176) connected to the other end of the air intake port (170) to heat the external air to room temperature; an environmental gas sensor (190) for measuring the concentration of environmental gas contained in the heated external air; a temperature sensor (210) for measuring the temperature of the external air that has passed through the environmental gas sensor (190); a pump inlet pipe (220) having one end connected to the environmental gas sensor (190) and an intermediate area passing through the temperature sensor (210); and an air pump (230) connected to the other end of the pump inlet pipe (220), with an outlet (235) exposed to the internal space (160). A high-altitude atmospheric gas measuring device for a radiosonde is provided, characterized by comprising: a control unit (200) that controls a heater (176) based on the output of a temperature sensor (210); an X-data communication module (260) that transmits the output signal of an environmental gas sensor (190) to the outside; and a battery (180) that supplies power to a high-altitude atmospheric environmental gas measuring device (100).
[0012] Optionally, the insulation pack comprises: an inner insulation pack (110) in which an upper atmosphere environmental gas measuring device (100) is accommodated inside; and an inner insulation cap (140) that forms one side of the inner insulation pack (110) and is assembled to be openable and closable.
[0013] Optionally, an external insulation pack (130) in which an internal insulation pack (110) is assembled; and an external insulation cap (120) that forms one side of the external insulation pack (130) and is assembled to be openable and closable.
[0014] Optionally, a hot pack (150) is further provided between the inner insulation cap (140) and the outer insulation cap (120).
[0015] Optionally, it further includes a heater insulation pack (172) that surrounds the heater (176) within the internal space (160).
[0016] Optionally, the room temperature is in the range of 20℃ to 24℃.
[0017] Optionally, the environmental gas is at least one of O3, NO2, and SO2.
[0018] Optionally, the environmental gas sensor (190) is a solid polymer electrolyte type gas sensor.
[0019] Optionally, the insulation pack contains styrofoam.
[0020] The objective of the present invention as described above can also be achieved by a radiosonde (300) characterized by including, as another embodiment, the aforementioned first upper atmosphere environmental gas measuring device (100a); and at least one second upper atmosphere environmental gas measuring device (100b) serially connected to the first upper atmosphere environmental gas measuring device (100a) via an X-data communication line (250).
[0021] The objective of the present invention as described above is, as another category, a measurement method using the aforementioned upper atmosphere environmental gas measuring device (100), comprising the steps of: inhaling upper atmosphere outside air at a temperature below zero (e.g., -70℃ to -20℃) through an air intake port (170) (S100); heating the outside air to room temperature using a heater (176) (S120); measuring the concentration of environmental gas contained in the outside air using an environmental gas sensor (190) (S140); transmitting the output signal of the environmental gas sensor (190) to the outside through an X-data communication module (260) by a control unit (200) (S150); measuring the temperature of the air discharged from the environmental gas sensor (190) using a temperature sensor (210) (S160); and controlling the power of the heater (176) based on the measured temperature by the control unit (200) (S200, S210). This can also be achieved by a method for measuring upper atmospheric environmental gases, characterized by including: a step (S220) in which an air pump (230) discharges air that has passed through a temperature sensor (210) into an internal space (160); and a step (S240) in which the air heats the internal space (160) and is then discharged to the outside through an internal insulation pack (130) and an external insulation pack (110).
[0022] Optionally, the step of controlling the power of the heater (176) (S200, S210) includes: a step (S200) in which the control unit (200) supplies additional power to the heater (176) when the measured temperature is below a reference value; and a step (S210) in which the control unit (200) cuts off or reduces the power supplied to the heater (176) when the measured temperature exceeds a reference value. Effects of the invention
[0023] According to one embodiment of the present invention, compared to conventional ozone sensors using an electrochemical concentration cell (ECC), the use of a solid electrolyte type sensor results in very low manufacturing costs and ultra-lightweight design. Furthermore, the pretreatment process before launching the radiosonde is simple, and the sensor can be attached to a commercial radiosonde with only simple operation, enabling economical and efficient measurement of environmental gases in the upper atmosphere.
[0024] In addition, according to the present invention, since it is very lightweight, the size of the balloon used for radiosonde launch can be reduced, thereby reducing helium consumption.
[0025] In addition, according to the present invention, multiple environmental gas measuring devices can be mounted on a single radiosonde launch, so there is an advantage of being able to measure multiple environmental gases simultaneously. For example, if n radiosondes are launched simultaneously, up to 2n environmental gases can be measured simultaneously.
[0026] However, the effects obtainable from the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing
[0027] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings. FIG. 1 is an internal configuration diagram of an upper atmosphere environmental gas measuring device (100) for a radiosonde according to a first embodiment of the present invention. FIG. 2 is a schematic block diagram of the upper atmosphere environmental gas measuring device (100) shown in FIG. 1. FIG. 3 is a configuration diagram of a radiosonde (300) in which a plurality of upper atmospheric environmental gas measuring devices (100) are configured in series according to a second embodiment of the present invention. FIG. 4 is a flowchart schematically illustrating a method for measuring upper atmospheric environmental gases for a radiosonde according to the present invention. Specific details for implementing the invention
[0028] Below, with reference to the attached drawings, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, since the description of the present invention is merely an example for structural or functional explanation, the scope of the present invention should not be interpreted as being limited by the embodiments described in the text. That is, since the embodiments are subject to various modifications and may take various forms, the scope of the present invention should be understood to include equivalents capable of realizing the technical concept. Furthermore, the objectives or effects presented in the present invention do not imply that a specific embodiment must include all of them or only such effects; therefore, the scope of the present invention should not be understood as being limited by them.
[0029] The meaning of the terms described in this invention should be understood as follows.
[0030] Terms such as "first" and "second" are intended to distinguish one component from another, and the scope of rights shall not be limited by these terms. For example, the first component may be named the second component, and similarly, the second component may be named the first component. When a component is referred to as being "connected" to another component, it should be understood that it may be directly connected to that other component, or that there may be other components in between. Conversely, when a component is referred to as being "directly connected" to another component, it should be understood that there are no other components in between. Meanwhile, other expressions describing the relationship between components, such as "between" and "exactly between," or "adjacent to" and "directly adjacent to," shall be interpreted in the same manner.
[0031] A singular expression should be understood to include a plural expression unless the context clearly indicates otherwise, and terms such as "include" or "have" are intended to specify the existence of the set-up features, numbers, steps, actions, components, parts, or combinations thereof, and should be understood not to preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.
[0032] Unless otherwise defined, all terms used herein have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having meanings consistent with the context of the relevant technology and should not be interpreted as having an ideal or overly formal meaning unless explicitly defined in this invention.
[0033] Composition of the first embodiment
[0034] Hereinafter, the configuration of a preferred first embodiment will be described in detail with reference to the attached drawings.
[0035] FIG. 1 is an internal configuration diagram of an upper-air atmospheric environmental gas measuring device (100) for a radiosonde according to a first embodiment of the present invention, and FIG. 2 is a schematic block diagram of the upper-air atmospheric environmental gas measuring device (100) shown in FIG. 1. As shown in FIG. 1 and FIG. 2, the insulation pack has a rectangular shape and has an internal space (160). This insulation pack is composed of an outer insulation pack (110), an outer insulation cap (120), an inner insulation pack (130), and an inner insulation cap (140).
[0036] The internal insulation pack (130) and the internal insulation cap (140) are formed as rectangular prisms in which an internal space (160) is defined, and the internal insulation cap (140) forms the upper surface of the internal insulation pack (130) and is assembled to be openable and closable. The internal insulation pack (130) and the internal insulation cap (140) are made of insulating material such as styrofoam and function to maintain a constant internal temperature while preventing cold outside air from entering.
[0037] The external insulation pack (110) and the external insulation cap (120) accommodate the internal insulation pack (130) and the internal insulation cap (140) inside and form a rectangular prism. The external insulation cap (120) forms the upper surface of the external insulation pack (110) and is assembled to be openable and closable. The external insulation pack (110) and the external insulation cap (120) are made of insulating material such as styrofoam and function to maintain a constant internal temperature while preventing cold outside air from entering.
[0038] Additionally, a space is formed between the inner insulation cap (140) and the outer insulation cap (120), and a hot pack (150) is further provided. This hot pack (150) functions to heat the upper atmosphere environmental gas measuring device (100) uniformly throughout. The outer insulation cap (120) is opened and the hot pack (150) is placed on the non-radiation of the radiosonde (300), and then the outer insulation cap (120) is closed. Optionally, the hot pack (150) may be omitted.
[0039] The air intake (170) is a long, thin non-metallic tube, one end of which is exposed to the outside of the external insulation pack (110), the middle section of which passes through the external insulation pack (110) and the internal insulation pack (130), and the other end of which is connected to the heater capsule (174). Cold air from the outside (e.g., -70°C to -20°C) is introduced through the air intake (170).
[0040] One end of the heater capsule (174) is connected to an air intake (170), and the other end is connected to a heated air tube (178), and a heater (176) is provided inside. The heater (176) uses a heater coated with Tetron to heat the incoming cold air to room temperature (e.g., 20°C to 24°C). Additionally, to increase the heating performance of the heater (176), a heater insulation pack (172) surrounding the heater (176) is further included. The heater insulation pack (172) can be made of styrofoam or the like.
[0041] One end of the heating air tube (178) is connected to the heater capsule (174), and the other end is connected to the environmental gas sensor (190).
[0042] The environmental gas sensor (190) is a solid polymer electrolyte type gas sensor and measures the concentration of environmental gases (e.g., O3, NO2, SO2, etc.) contained in the external air. The environmental gas sensor (190) is installed within the internal space (160). The solid polymer electrolyte type gas sensor is smaller (e.g., 10×10×10 mm) compared to the conventional liquid electrolyte type. 3 It is lightweight (e.g., 5 to 10 g) and inexpensive (e.g., $40 to $60). Also, since the environmental gas sensor (190) of this embodiment is for ground use, it does not operate properly in ultra-low temperature air (e.g., -70°C to -20°C). Therefore, it is preheated to room temperature using a heater (176) before measurement. Additionally, the indoor space (160) is also maintained at a constant temperature through insulation so that the environmental gas sensor (190) operates normally.
[0043] One end of the pump inlet pipe (220) is installed at the outlet of the environmental gas sensor (190), the middle section passes through the temperature sensor (210), and the other end is connected to the inlet of the air pump (230).
[0044] The temperature sensor (210) measures the temperature of the outside air that has passed through the environmental gas sensor (190) and transmits it to the control unit (200).
[0045] An air pump (230) is installed within an internal space (160), with an inlet connected to a pump inlet pipe (220) and an outlet (235) exposed within the internal space (160). Since the discharged air is at room temperature, rather than being discharged directly into the atmosphere, it passes through the internal space (160) to heat the internal space (160), and then is discharged into the atmosphere through a gap created by the internal insulation cap (140) and the external insulation cap (120). The air pump (230) can be replaced with a vacuum pump, a compressor, etc.
[0046] The control unit (200) can be a printed circuit board (PCB) provided on the inner bottom surface of the internal insulation pack (110), and can be implemented as a CPU (central processing unit), MICOM (microcomputer), AP (application processor), PLC (programmable logic controller), etc.
[0047] The X-data communication module (260) transmits the output signal of the environmental gas sensor (190) to the outside. To this end, the X-data communication module (260) is equipped with first and second X-data connectors (240, 245) and an X-data communication line (250) connecting them. In particular, the first X-data connector (240, 245) can be mounted on the control unit (200), and the second X-data connector (245) can be exposed to the outside through an external insulation pack (110). The second X-data connector (245) is composed of an X-data IN terminal and an X-data OUT terminal.
[0048] The battery (180) is provided within the internal space (160) and supplies power to the high-altitude atmospheric environment gas measuring device (100).
[0049] Operation of the first embodiment
[0050] FIG. 4 is a flowchart schematically illustrating a method for measuring upper-air atmospheric environmental gas for a radiosonde according to the present invention. As shown in FIG. 4, first, as the air pump (230) operates, upper-air external air at sub-zero temperatures (e.g., -70℃ to -20℃) is sucked in through the air intake (170) (S100).
[0051] Next, the heater (176) heats the outside air to room temperature (e.g., 20°C to 24°C) (S120). In this embodiment, the heater (176) heats the outside air to a range of 20 ± 5°C.
[0052] Next, the environmental gas sensor (190) measures the concentration of environmental gas contained in the outside air (S140). Then, the measured concentration is transmitted to and stored in the control unit (200).
[0053] Next, the control unit (200) transmits the output signal of the environmental gas sensor (190) to the outside through the X-data communication module (260) (S150). Thus, a worker on the ground can receive the concentration of the environmental gas in real time through X-data communication.
[0054] Next, the temperature sensor (210) measures the temperature of the air emitted from the environmental gas sensor (190) (S160). The measured temperature is transmitted to the control unit (200).
[0055] The control unit (200) controls the power of the heater (176) based on the measured temperature (S200, S210). More specifically, if the measured temperature is below a reference value (e.g., 20℃), the control unit (200) supplies additional power to the heater (176) to heat the outside air more hot (S200). If the measured temperature exceeds a reference value (e.g., 22℃), the control unit (200) cuts off or reduces the power supplied to the heater (176) to heat or cool the outside air less hot (S210).
[0056] To this end, the control unit (200) can select algorithms such as on / off control, proportional (P) control, proportional derivative (PD) control, proportional integral (PI) control, and proportional derivative integral (PID) control.
[0057] Next, the air pump (230) discharges the air that has passed through the temperature sensor (210) into the internal space (160) (S220). Through this, the internal space (160) is heated to a temperature close to room temperature, and waste heat can be further utilized for maintaining the temperature. In addition, by maintaining the temperature of the internal space (160), malfunctions of the control unit (200) and sensors can be reduced.
[0058] Next, after the air heats the internal space (160), it is discharged to the outside through the internal insulation pack (130) and the external insulation pack (110) (S240).
[0059] Second embodiment
[0060] Hereinafter, a second embodiment will be described in detail with reference to the attached drawings. FIG. 3 is a configuration diagram of a radiosonde (300) in which a plurality of upper atmosphere environmental gas measuring devices (100) are configured in series according to the second embodiment of the present invention. As shown in FIG. 3, a plurality of environmental gas measuring devices are connected in series to the radiosonde (300). For example, in FIG. 3, the first environmental gas measuring device (100a) is connected in series between the radiosonde (300) and the second environmental gas measuring device (100b) via an X-data communication line (250a). That is, one end of the X-data communication line (250a) is connected to the X-data IN of the first environmental gas measuring device (100a), and the other end of the X-data communication line (250a) is connected to the X-data OUT of the second environmental gas measuring device (100b). By repeating this series connection, a plurality of environmental gas measuring devices (100a, 100b, 100c, ...) are provided.
[0061] At this time, the first environmental gas measuring device (100a) is dedicated to measuring the concentration of ozone, and the second environmental gas measuring device (100b) is dedicated to measuring the concentration of SO2.
[0062] As described above, the detailed description of the preferred embodiments of the present invention disclosed is provided to enable those skilled in the art to implement and practice the present invention. Although the present invention has been described with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the scope of the invention. For example, those skilled in the art may utilize each configuration described in the embodiments described above in combination with one another. Accordingly, the present invention is not intended to be limited to the embodiments shown herein, but to be given the broadest scope consistent with the principles and novel features disclosed herein.
[0063] The present invention may be embodied in other specific forms without departing from the spirit and essential features of the invention. Accordingly, the above detailed description should not be interpreted restrictively in all respects but should be considered exemplary. The scope of the invention shall be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the invention are included within the scope of the invention. The invention is not intended to be limited to the embodiments shown herein, but to be given the broadest possible scope consistent with the principles and novel features disclosed herein. Furthermore, embodiments may be constructed by combining claims that are not explicitly related in the claims, or by including them as new claims through amendments made after filing. Explanation of the symbols
[0064] 100 : Upper atmospheric environmental gas measuring device, 100a : 1st upper atmosphere environmental gas measuring device, 100b : Second upper atmosphere environmental gas measuring device, 110 : External insulation pack, 120 : External insulation cap, 130 : Internal insulation pack, 140 : Internal insulation cap, 150 : Hot pack, 160 : Interior space, 170 : Air intake, 172 : Heater insulation pack, 174 : Heater Capsule, 176 : Heater, 178 : Heated air tube, 180 : Battery, 190 : Environmental gas sensor, 200 : Control unit, 210 : Temperature sensor, 220 : Pump inlet pipe, 230 : Air pump, 235 : Outlet, 240 : 1st X-Data Connector, 245 : 2nd X-Data Connector, 250, 250a, 250b : X-data communication lines, 260 : X-Data communication module, 300 : Radiosonde.
Claims
Claim 1 In a high-altitude atmospheric environmental gas measuring device (100) for a radiosonde (300), the device comprises: an insulating pack having an internal space (160); an air intake port (170) having one end exposed to the outside of the insulating pack to allow external air to flow in, and the other end extending to the internal space (160); a heater (176) connected to the other end of the air intake port (170) to heat the external air to room temperature; an environmental gas sensor (190) for measuring the concentration of environmental gas contained in the heated external air; a temperature sensor (210) for measuring the temperature of the external air that has passed through the environmental gas sensor (190); a pump inlet pipe (220) having one end connected to the environmental gas sensor (190) and an intermediate area passing through the temperature sensor (210); an air pump (230) connected to the other end of the pump inlet pipe (220) and having an outlet (235) exposed to the internal space (160); and the A high-altitude atmospheric gas measuring device for a radiosonde, characterized by comprising: a control unit (200) that controls the heater (176) based on the output of the temperature sensor (210); an X-data communication module (260) that transmits the output signal of the environmental gas sensor (190) to the outside; and a battery (180) that supplies power to the high-altitude atmospheric environmental gas measuring device (100). Claim 2 A high-altitude atmospheric gas measuring device for a radiosonde according to claim 1, wherein the insulation pack comprises: an inner insulation pack (110) in which the high-altitude atmospheric environmental gas measuring device (100) is accommodated inside; and an inner insulation cap (140) that forms one side of the inner insulation pack (110) and is assembled to be openable and closable. Claim 3 A high-altitude atmospheric environment gas measuring device for a radiosonde, characterized in that, in claim 2, it comprises: an external insulation pack (130) in which the internal insulation pack (110) is assembled; and an external insulation cap (120) that forms one side of the external insulation pack (130) and is assembled to be openable and closable. Claim 4 A high-altitude atmospheric environment gas measuring device for a radiosonde, characterized in that, in claim 3, a hot pack (150) is further provided between the inner insulation cap (140) and the outer insulation cap (120). Claim 5 A high-altitude atmospheric environment gas measuring device for a radiosonde, characterized in that, in claim 1, it further includes a heater insulation pack (172) surrounding the heater (176) within the internal space (160). Claim 6 An upper-air atmosphere environmental gas measuring device for a radiosonde, characterized in that, in claim 1, the room temperature is in the range of 20℃ to 24℃. Claim 7 A high-altitude atmospheric environmental gas measuring device for a radiosonde, characterized in that, in claim 1, the environmental gas is at least one of O3, NO2, and SO2. Claim 8 A high-altitude atmospheric environmental gas measuring device for a radiosonde, characterized in that, in claim 1, the environmental gas sensor (190) is a solid polymer electrolyte type gas sensor. Claim 9 A high-altitude atmospheric environment gas measuring device for a radiosonde, characterized in that, in claim 1, the insulation pack comprises styrofoam. Claim 10 A radiosonde (300) characterized by comprising: a first upper atmosphere environmental gas measuring device (100a) according to any one of claims 1 to 9; and at least one second upper atmosphere environmental gas measuring device (100b) serially connected to the first upper atmosphere environmental gas measuring device (100a) via an X-data communication line (250). Claim 11 A measurement method using an upper atmosphere environmental gas measuring device (100) according to any one of claims 1 to 9, comprising: a step (S100) in which sub-zero upper atmosphere outside air is sucked in through an air intake (170); a step (S120) in which a heater (176) heats the outside air to room temperature; a step (S140) in which an environmental gas sensor (190) measures the concentration of environmental gas contained in the outside air; a step (S150) in which a control unit (200) transmits the output signal of the environmental gas sensor (190) to the outside through an X-data communication module (260); a step (S160) in which a temperature sensor (210) measures the temperature of the air discharged from the environmental gas sensor (190); and a step (S200, S210) in which the control unit (200) controls the power of the heater (176) based on the measured temperature. A method for measuring upper atmospheric environmental gas, characterized by including: a step (S220) in which an air pump (230) discharges the air that has passed through the temperature sensor (210) into an internal space (160); and a step (S240) in which the air heats the internal space (160) and then discharges it to the outside through an internal insulation pack (130) and an external insulation pack (110). Claim 12 A method for measuring upper atmospheric environmental gas according to claim 11, wherein the step of controlling the power of the heater (176) (S200, S210) comprises: a step (S200) in which the control unit (200) supplies additional power to the heater (176) when the measured temperature is below a reference value; and a step (S210) in which the control unit (200) cuts off or reduces the power supplied to the heater (176) when the measured temperature exceeds a reference value.