• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.505-510
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• 2002

We have focused on the development of a fiber optic BOTDA (Brillouin Optical Time Domain Analysis) sensor system in order to measure temperature distributed on large structures. Also, we present a feasibility study of the fiber optic sensor to monitor the distributed temperature on a building construction. A fiber optic BOTDA sensor system, which has a capability of measuring the temperature distribution, attempted over several kilometers of long fiber paths. This simple fiber optic sensor system employs a laser diode and two electro-optic modulators. The optical fiber of the length of 1400 m was installed on the surfaces of the building. The change of the distributed temperature on the building construction was well measured by this fiber optic sensor. The temperature changed normally up to 4℃ through one day.

• 센서학회지
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• 제14권6호
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• pp.395-401
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• 2005

A highly stable quartz crystal microbalance (QCM) that showed a stability of frequencies and exhibited a very low noise level has been developed. The long-term drift was <0.05 Hz/h over a period of 10 h, and the short-term rms (root mean square) noise was <0.015 Hz. Our QCM sensor was used as a humidity sensor employing a poly(methyl methacrylate) (PMMA) polymer film as a hygroscopic layer, which showed good characteristics in the relative humidity (RH) range of $2{\sim}90%$ RH. Comparing the characteristics of the QCM sensor with those of other types of humidity sensors employing PMMA film as a hygroscopic layer, and with other QCM sensors employing other hygroscopic layers is represented.

• 한국정밀공학회지
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• 제32권2호
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• pp.185-190
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• 2015

This paper presents a new method to determine sensitivity coefficients of temperature and humidity of torque transducers by using a natural and seasonal variation of ambient conditions at the laboratory. We had measured the sensitivities of the torque transducers over almost one year using the KRISS 2 kN m torque standard machine. The sensitivity data acquired at various ambient conditions were processed using our measurement model to extract the sensitivity coefficients of temperature and humidity simultaneously with high precision. A comparison with a previous method using an environmental control chamber was carried out to test the feasibility of using our new method. Two results agreed within the uncertainty. We revealed that the torque measuring errors could be 8 times higher than the measurement and calibration capability of KRISS torque standard machine if the sensitivity changes due to the temperature and humidity are not properly corrected during a calibration.

• 대한기계학회논문집A
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• 제36권9호
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• pp.1053-1057
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• 2012

본 연구에서는 풍력 발전 블레이드용 재료인 GFRP(Glass fiber-Reinforced Plastic) 복합재의 인장특성의 온도에 따른 의존성을 고찰하였다. 섬유 방향이 $0^{\circ}$와 $0/{\pm}45^{\circ}$로 적층된 두 종류의 복합재로 제작된 인장 시험편으로부터 인장 강도와 탄성계수 그리고 푸아송비에 대한 특성을 상온, $-30^{\circ}C$, $-50^{\circ}C$ 그리고 $60^{\circ}C$에서 측정하였다. 인장 시험으로부터 섬유방향이 축방향으로 적층된 복합재의 인장강도와 탄성 계수는 섬유 적층 방향의 의존성을 보였고 단축으로 적층된 복합재의 강도 및 탄성 계수가 상대적으로 우수함을 보았다. 그리고 시험온도의 의존성도 확인할 수 있었으며, 푸아송비는 온도의 영향이 크지 않음을 확인할 수 있었다.

• Progress in Superconductivity
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• 제6권1호
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• pp.24-31
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• 2004

Magnetic $T_{c}$ of composite superconductors has been studied for providing a standard method. Various magnetization-temperature curves of NbTi, $Nb_3$Sn and Bi-2223 wires were measured using a SQUID magnetometer. Magnetization-temperature curve of zero-field-cooled procedure showed larger values than fie Id-cooled procedure. To obtain higher resolution near the onset temperature, we employed a two-field-direction method which measures a magnetization-temperature curve of a specimen first in positive and then negative fields. Analytical comparison of the magnetic $T_{c}$, with the resistive T$_{c}$ was accomplished for three specimens. The magnetic $T_{c}$/ mettled showed more detailed information on superconducting state of a specimen than the resistive$T_{c}$/ method. We have also studied the field dependence of the magnetic $T_{c}$ from 5 Oe to 120 Oe, however, no significant difference on field strength was found in our three specimensns

• 센서학회지
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• 제15권4호
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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.

• 센서학회지
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• 제31권6호
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• pp.448-454
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• 2022

An intralaboratory comparison of the realization of the triple-point temperature of mercury, which is defined as -38.8344℃ on the international temperature scale of 1990 (ITS-90), was conducted at the Korea Research Institute of Standards and Science (KRISS), the national metrology institute of Korea. To this end, four triple-point-of-mercury cells were compared using the resistance ratio measurement of a standard platinum resistance thermometer to validate the calibration results obtained using the triple-point-of-mercury cells at KRISS. The triple-point temperatures of all the four cells, one of which is designated as the national standard cell, were within 0.3 mK of the national standard. Based on 13 experiments on the four triple-point-of-mercury cells, the uncertainty in the comparison of the triple-point-of-mercury cells was 0.08 mK, and the uncertainty in the realization of the triple-point temperature of mercury was 0.19 mK. The results of the intralaboratory comparison validated that utilizing any of the four triple-point-of-mercury cells would result in the realization of a temperature within 0.3 mK of the average value determined by two key international comparisons for the realization of -38.3844℃ following the ITS-90.

• 센서학회지
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• 제13권6호
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• pp.411-416
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• 2004

In the international temperature scale of 1990 (ITS-90), standard platinum resistance thermometer (SPRT) is a defining standard thermometer used in the temperature range from 13.8033 K to $961^{\circ}C$. Uncertainty of SPRT is about several mK and uncertainty of defining fixed points of the ITS-90 which is used for calibrating SPRT is about several tenth of mK. Above $0^{\circ}C$. the defining fixed points are gallium melting point and indium, tin, zinc, aluminium and silver freezing points which are all realized using an electric furnace or a liquid bath. To realize freezing point of tin ($231.928^{\circ}C$) and zinc ($419.527^{\cir}C$), two 3-zone furnaces which have 3 electric heaters were manufactured. Temperature gradient of the constructed furnaces were tested. Uncertainty caused by temperature gradient of furnace and immersion effect of SPRT in the sealed-type freezing point cells were evaluated 0.038 mK for tin freezing point and 0.036 mK for zinc freezing point.

• 한국광학회지
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• 제21권3호
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• pp.103-110
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• 2010

13 km 광섬유를 통해 1.4 GHz의 기준 주파수를 전송할 때, 광섬유에서 발생하는 위상잡음을 제거하는 시스템을 구성하였다. 전송된 주파수의 안정도 성능은 실험장치의 온도변화폭에 의존하였다. 실험실의 온도변화폭이 $0.3^{\circ}C$ 이내로 유지되는 동안에는 광섬유의 위상잡음을 제거했을 때, 원격지에 전송된 신호가 0.8초의 평균 시간에서 $4.6{\times}10^{-14}$, 1000초의 평균 시간에서 $2.5{\times}10^{-16}$의 상대주파수 전송 안정도를 보여 만족할 만한 결과이었으나, 실험실의 온도가 $3.5^{\circ}C$ 범위로 변할 때에는, 1.2초의 평균 시간에서 $6.8{\times}10^{-14}$, 1000초의 평균 시간에서 $3.0{\times}10^{-15}$의 전송 안정도를 보였다. 이 결과로부터 1000초의 평균시간에서 $10^{-16}$ 수준의 상대주파수 안정도를 얻기 위해서 요구되는 실험장치의 온도 안정도 조건을 제시할 수 있었다.

• 한국가스학회:학술대회논문집
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• 한국가스학회 1998년도 추계학술발표회 논문집
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• pp.334-339
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• 1998