• Title/Summary/Keyword: dew sensor

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Development of QCM dew point sensor and its sensing characteristics study (수정미소저울 노점센서 제작 및 반응특성 연구)

  • Kwon, Su-Yong;Kim, Jong-Chul;Choi, Byung-Il
    • Journal of Sensor Science and Technology
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    • v.15 no.4
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    • pp.269-276
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    • 2006
  • This paper represents development of quartz crystal microbalance (QCM) and usage as a dew point sensor. The temperature of a quartz resonator was controlled precisely from $20^{\circ}C$ to $-30^{\circ}C$ with the ramping rate of $0.1^{\circ}C/s$ by using a custom-made crystal holder housing the quartz resonator associated with a thermoelectric cooler (Peltier cooler), which results in the working range from $15.2^{\circ}C$ to $-24.0^{\circ}C$ based on an accurate holder temperature compensation and temperature effect compensation process. The developed QCM dew point sensor and analysis techniques show very good sensing characteristics at measurement of moist air with the relative humidity from 10 %R.H. to 90 %R.H. generated by a divided-type humidity generator and the dew point temperatures were determined with an accuracy of less than ${\pm}0.18^{\circ}C$, which also showed good agreement with reference values in their error range.

The Effect of Temperature on Aluminum Oxide and Chilled Mirror Dew-point Hygrometers (산화 알루미늄 및 냉각거울 노점계의 온도 의존성에 관한 연구)

  • Kim, Jong Chul;Choi, Byung Il;Woo, Sang-Bong;Kim, Yong-Gyoo;Lee, Sang-Wook
    • Journal of Sensor Science and Technology
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    • v.26 no.1
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    • pp.50-55
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    • 2017
  • The measurement of absolute humidity of gases is essential in many industries. The effect of temperature on aluminum oxide and chilled mirror dew-point hygrometers is investigated. The temperature of laboratory, pipe line, and sensor is varied and the dew point is measured by two different aluminum oxide hygrometers. In all cases, the dew point of hygrometers is increased as the temperature is elevated. The reason behind this observation is due to desorption of water from the inside of pipe line and/or sensor surroundings at elevated temperature that result in the increase of the absolute humidity. Moreover, the sensor itself shows a certain degree of temperature dependency in sensing the humidity especially at low temperature. It is also studied that chilled mirror dew-point hygrometer may indicate a higher dew point than the reference at high temperature because the cooling capability of mirror is decreased at high temperature. Our study will provide evidences in the incorporation of the temperature effect as uncertainty factors in the standard calibration procedure for dew point hygrometers.

Humidity-Sensitive Characteristics and Reliabilities of Polymeric Humidity Sensor Containing Phosphonium Salts (포스포늄 염을 가진 고분자 습도센서의 감습 특성 및 신뢰성)

  • Kim, Ohyoung;Gong, Myoung-Seon
    • Applied Chemistry for Engineering
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    • v.9 no.4
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    • pp.554-560
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    • 1998
  • Vinylbenzyl triphenyl phosphonium chloride(VTPC)/styrenes=3.7 copolymer was prepared for the moisture-absorptive polyelectrolyte dew sensor containing phosphonium salts. The humid membrane was fabricated on the gold/alumina electrode by dipping. The impedances were $11M{\Omega}$, $980k{\Omega}$, $50k{\Omega}$, and $11k{\Omega}$ at 70%RH, 80%RH, 90%RH and 95%RH, respectively, at $25^{\circ}C$ and the humidity-sensitive charactristic was suitable for the dew sensor. The temperature-dependent coefficient between $15^{\circ}C$ and $35^{\circ}C$ was found to be $-0.25%RH/^{\circ}C$ and the hysteresis falled in the ${\pm}2%RH$ range. The response time was found to be 45 sec for the relative humidity ranging from 70%RH to 98%RH at $25^{\circ}C$. The reliabilities such as temperature cycle, humidity cycle, high temperature and humidity resistance, electrical load stability, stability of long-term storage and water durability were measured and evaluated for the application as a dew sensor.

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Humidity-Sensitive Properties of Self-Assembled Polyelectrolyte System

  • Lee Chil-Won;Kim Jong-Gyu;Gong Myoung-Seon
    • Macromolecular Research
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    • v.13 no.3
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    • pp.265-272
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    • 2005
  • Polyelectrolyte membranes for humidity-sensing were fabricated using a layer-by-layer adsorption process based on the spontaneous self-assembly of alternating layers of cationic and anionic polymers on a silanized ITO patterned glass substrate. The substrate is dipped successively into dilute solutions of a polyanion and a polycation. The homopolymers and copoymers of diallyldimethylammonium chloride (DDA), allylamine hydrochloride (AA), 2-[(methacryloyloxy)ethyl]trimethyl ammonium chloride (METAC) and vinylbenzyl tributyl phosphonium chloride(VTBPC) were used as the polycations. In this experiment, it was found that the resistance varied according to the chemical structure of the polycation. The resistance varied from $10^7$ to $10^5$ $\Omega$, as the humidity was increased from 60 (relative humidity) to $95\%$RH, which is the range of RH values required for a dew sensor operating at high humidity.

Analysis of Water Transport through Measurement of Temperature and Relative Humidity in PEMFC at OCV (개방회로 상태 PEMFC 내부 온도와 습도 측정을 통한 수분투과 분석)

  • KIM, TAEHYEONG;HAN, JAESU;YU, SANGSEOK
    • Journal of Hydrogen and New Energy
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    • v.33 no.4
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    • pp.353-362
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    • 2022
  • In this study, water diffusion in proton exchange membrane fuel cell at open circuit voltage (OCV) was analyzed through experiment. First, the reliability of the micro-sensor (SHT31) was verified. It was concluded the micro-sensor has an excellent reliability at 60℃ and 70℃. After the sensor reliability test, the temperature and relative humidity measurement in bipolar-plate was conducted at OCV. To analyze water distribution and water flux, the temperature and relative humidity was converted into dew point. To the end, it was found water concentration affects water diffusion.

An Experimental Study on the Measurement of Water Content in an Lubricating Oil by Implementing a Dew-point Condensation Sensor (이슬점 응축 현상을 이용한 오일 내 수분함량 측정에 관한 실험적 연구)

  • Kong Hosung;Yoon Eui-Sung;Han Hung-Gu;Kim Hak Yeul
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2004.11a
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    • pp.130-136
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    • 2004
  • Presence of water in the lubricating oils could be one of the first indicators of potentially expensive and possibly catastrophic failure of the machine as it may cause displace the oil films to prevent the lubrication function of the oil or chemically react with many oil additives resulting in the oil degradation. In order to detect water content quantitatively in lubricating oils many methods and sensors has been developed. Among these, capacitive sensors including sensitive layer, whose dielectric factor changes according to the water content absorbed in the layer, are proposed mainly in the market. But these sensors are not sensitive to a high water content. Besides, the absorbing layer soils in time. In this work, an evaporation of water moisture from oil into air volume above lubricant surface and condensation of water vapor at a cooling surface was used to measure water content quantitatively in an lubricating oil. Laboratory test results of a prototype sensor were presented. Test results showed that the proposed method could be avaliable to measure a low levels of oil moisture.

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Leakage Rates Measurement System Development of NPP Primary Containment using Wireless Data Communication Method (원전 격납건물 누설시험용 무선데이터전송을 적용한 시험장치 개발)

  • Ryu, Jae-Kyu;Sohn, Chang-Ho;Hwang, Hee-Jung;Kim, Gun-Soo;Choi, Kyong-Sik
    • Proceedings of the KIEE Conference
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    • 2003.11c
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    • pp.916-919
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    • 2003
  • In this paper, we deal with a development of measurement system to apply the leakage rates test of primary containment in nuclear power plant. The measurement test about leakage rates in primary containment is one sort of test to prove safety of nuclear power plant. The parameters which are measured to calculate leakage rates are drybulb temperature, dew point temperature(or relative humidity), absolute pressure and flow. Overall, the measurement system consists of sensor module for data acquisition of the parameters, transfer module for wireless data communication and control module to control system and to calculate leakage rates. Because existing measurement systems are difficult to set in field, we pursued convenience of use, we applied wireless data communication and individual form module using battery. We also changed for the better in confidence. Recently, we are developing a drybulb temperature and a dew point temperature sensor module. We describe about function of developed measurement system, its standard and an plan for verification of measurement system.

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Embedded System for Automatic Condensation Control of the Car

  • Lee, Dmitriy;Bae, Yong-Wook;Lee, Neung-Ho;Seo, Hee-Don
    • Journal of Sensor Science and Technology
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    • v.21 no.1
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    • pp.21-27
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    • 2012
  • In this study, we designed an embedded system for automatic condensation control(ESCC) of the car. This system heats the car glasses as and when it is needed that makes driving safer and convenient. The system was built on an ATmega128L central processing unit(CPU), using high-performance electrically erasable programmable read-only memory(EEPROM) complex programmable logic device(CPLD) ATF1504AS, using which an ESCC algorithm has been proposed. The source code was written in C language. The algorithm of work was written using the dew-point table. This system not only clears the condensation on the glass but also averts condensation. The designed ESCC system begins working once the input information comes close to the dew-point table information. This device enables a wider field of view, thereby increasing safety.

Intelligent Diagnostic System of Photovoltaic Connection Module for Fire Prevention (화재 예방을 위한 태양광 접속반의 지능형 진단 시스템)

  • Ahn, Jae Hyun;Yang, Oh
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.3
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    • pp.161-166
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    • 2021
  • To prevent accidents caused by changes in the surrounding environment or other factors, various protection facilities are installed at the photovoltaic connection module. The main causes of fire are sparks due to foreign substances inside the photovoltaic connection module through high temperature rise and dew condensation in the photovoltaic connection module, and fire due to heat from the power diode. The proposed method can predict the fire by measuring flame, carbon dioxide, carbon monoxide, temperature, humidity, input voltage, and current on the photovoltaic connection module, and when the fire conditions are reached, fire alarm and power off can be sent to managers and users in real time to prevent fire in advance.

Bridge Road Surface Frost Prediction and Monitoring System (교량구간의 결빙 예측 및 감지 시스템)

  • Sin, Geon-Hun;Song, Young-Jun;You, Young-Gap
    • The Journal of the Korea Contents Association
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    • v.11 no.11
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    • pp.42-48
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    • 2011
  • This paper presents a bridge road surface frost prediction and monitoring system. The node sensing hardware comprises microprocessor, temperature sensors, humidity sensors and Zigbee wireless communication. A software interface is implemented the control center to monitor and acquire the temperature and humidity data of bridge road surface. A bridge road surface frost occurs when the bridge deck temperature drops below the dew point and the freezing point. Measurement data was used for prediction of road surface frost occurrences. The actual alert is performed at least 30 minutes in advance the road surface frost. The road surface frost occurrences data are sent to nearby drivers for traffic accidents prevention purposes.