• 대한기계학회논문집B
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• 제24권10호
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• pp.1399-1408
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• 2000

A 2-dimensional temperature field measurement technique using PLIF (Planar Laser Induced Fluorescence) was developed and it was applied to an axisymmetric buoyant jet. Rhodamine B was used as a fluorescent dye. Laser light sheet illuminated a two-dimensional cross section of the jet. The intensity variations of LIF signal from Rhodamine B molecules scattered by the laser light were captured with an optical filter and a CCD camera. The spatial variations of temperature field of buoyant jet were derived using the calibration data between the LIF signal and real temperature. The measured results show that the turbulent jet is more efficient in mixing compared to the transition and laminar jet flows. As the initial flow condition varies from laminar to turbulent flow, the entrainment from ambient fluid increases and temperature decay along the jet center axis becomes larger. In addition to the mean temperature field, the spatial distributions of temperature fluctuations were measured by the PLIF technique and the result shows the shear layer development from the jet nozzle exit.

• 생태와환경
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• 제41권2호
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• pp.247-263
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• 2008

A two-dimensional (2D) reservoir hydrodynamics and water quality model, CE-QUAL-W2, is employed to simulate the hydrothermal behavior and density current regime in Andong Reservoir. Observed data used for model forcing and calibration includes: surface water level, water temperature, dissolved oxygen and suspended solids concentration. The model was calibrated to the year of 2003 and verified with continuous run from 2000 till 2004. Without major adjustments, the model accurately simulated surface water levels including the events of large storm. Deep-water reservoirs, like Andong Reservoir, located in the Asian Monsoon region begin to stratify in summer and overturn in fall. This mixing pattern as well as the descending thermocline, onset and duration of stratification and timing of turnover phenomenon were well reproduced by the Andong Model. The temperature field and distinct thermocline are simulated to within $2^{\circ}C$ of observed data. The model performed well in simulating not only the dissolved oxygen profiles but also the metalimnetic dissolved minima phenomenon, a common1y occurring phenomenon in deep reservoirs of temperate regions. The Root Mean Square Error (RMSE) values of model calibration for surface water elevation, temperature and dissolved oxygen were 0.0095 m, $1.82^{\circ}C$, and $1.13\;mg\;L^{-1}$, respectively. The turbid storm runoff, during the summer monsoon, formed an intermediate layer of about 15 m thickness, moved along the metalimnion until being finally discharged from the dam. This mode of transport of density current, a common characteristic of various other large reservoirs in the Asian summer monsoon region, was well tracked by the model.

• 한국전산구조공학회논문집
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• 제24권4호
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• pp.383-389
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• 2011

본 논문에서는 통계적인 방법을 이용하여 점탄성 제진재인 합성고무의 물성에 대한 변동성을 평가하는 방법을 제안하고 측정데이터를 이용하여 합성고무에 대한 평가를 수행하고 합성고무로 이루어진 고무 마운트에 대한 동특성 해석을 수행하였다. 고무 물성의 불확실성 인자로는 외기 온도의 변화와 실험 데이터의 오차 및 점탄성 물질모델의 오차를 고려하였다. 고무는 분수차 미분모델로 표현되었고, 온도의 영향은 비선형 이동계수모델을 도입하여 복소계수로 나타내어 동강성과 감쇠를 표현하였다. 이러한 물성모델을 바탕으로 고무에 대한 물성 실험데이터와 물성계수의 확률밀도함수 사이에 정의된 우도함수를 최대화하는 통계적 보정방법을 이용하여 물성모델의 물질계수들에 대한 변동성을 추정하였다. 합성고무로 이루어진 제진용 고무 마운트에 대하여 유한요소모델을 이용하여 동특성을 계산하였다. 동특성의 계산시 추정된 물성의 통계값을 적용하고 몬테카를로 해석을 통하여 동강성의 변동성을 살펴서 그 변동성이 매우 큼을 확인하였다.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.38-47
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• 2007

Based upon temperature calibration using the diffusion flame, the temperature and soot concentration of the turbulent flame in a visualized Diesel engine's turbulent flow of flame was qualitatively measured. Two different heads were used to judge the effect of swirl ratio within the combustion chamber. It was possible to measure the highest temperature of the non-swirl head visualized engine which is approximately 2400K, and that the swirl head engine managed up to 2100K. Also, the more the pressure of the spray increases the more the temperature increases due to the improved combustion situation with respect to the visualized diesel engine soot. This experiment also revealed that the KL factor was high where the fuel collided with the walls of the combustion chamber. Moreover the KL factor was high on parts of the chamber where the temperature dropped rapidly.

• 한국자동차공학회논문집
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• 제7권7호
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• pp.42-53
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• 1999

Two dimensional flame temperature and KL value distribution from the luminous flame containing soot in a DI diesel engine were measured by the tow-color method using tow different wavelengths of the flame image. The combustion chamber of a DI diesel engine was visualized by elongating the piston and cylinder and the flame in the combustion chamber was photographed on a nega-color film using a high speed camera. In this study, color CCD camera was used to digitize the three color density of the film exposed to the flame and standard lamp . The accuracy of the measuring method depends on the calibration line of film made from a high temperature standard tungsten lamp. The formation and oxidization of soot in the diesel engine were studied by observing measured time history of KL factor and flame temperature . Also , effects of various shapes of combustion chamber and fuel injection on flame temperature. Also, effects of various shapes of combustion chamber and fuel injection on flame temperature and KL value distribution were examined.

• 항공우주시스템공학회지
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• 제14권3호
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• pp.42-50
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• 2020

우주용 적외선 센서의 탑재 교정용 흑체 시스템은 궤도상에서 센서 출력특성 교정을 위해 다양한 기준온도에서 한정된 개수의 온도센서로부터 고정밀의 대표표면온도 추정이 가능해야 한다. 본 논문에서 제안된 흑체 시스템은 흑체 가열 후 잔열 수송을 위한 히트파이프를 흑체 후면 중앙의 일체형 플랜지에 결합하는 방식을 적용하였다. 따라서 흑체 표면온도구배 최소화와 함께 원형 대칭 형태의 온도구배를 얻을 수 있어 표면온도 추정이 용이하면서도 발사 및 궤도환경에서 하중이 가해지더라도 안정적인 히트파이프 접속부를 갖도록 하며, 복수의 히트파이프 적용에 따른 Fail Safe 설계가 가능하도록 한다. 또한 온도센서 부착작업이 용이하도록 센서를 흑체 외부 표면에 적용하더라도 높은 정확도로 표면온도 추정이 가능하다. 본 논문에서 제안된 흑체 시스템의 설계 유효성 입증을 위해 궤도 열해석을 수행하였으며, 해석결과를 기반으로 온도센서 개수 및 위치에 따른 대표표면온도 추정을 실시하였다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.462-467
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• 1999

In this paper, very high performance millimeter-wave radiometer of 92 GHz is presented. Radiometer system design, brightness temperature measurement and calibration methods are described. The architecture of radiometer including data acquisition, storage and digital signal processing using a notebook computer are explained and some experimental data in the laboratory are introduced. The system noise figure and total gain of implemented radiometer are 12 dB and 56 dB, respectively. The system stability is evaluated from the experiment. The difference of the detector output voltage for two targets, whose brightness temperature are 80 K and 300K, is 4 mV. The mechanical scanning method is considered to get a brightness temperature Image of the earth surface scene.

• 전기전자학회논문지
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• 제15권2호
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• pp.143-148
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• 2011

MOS (Metal-Oxide Semconductor) devices among the most sensistive of all semiconductors to radiation, in particular ionizing radiation, showing much change even after a relatively low dose. The necessity of a radiation dosimeter robust enough for the working environment has increased in the fields of aerospace, radio-therapy, atomic power plant facilities, and other places where radiation exists. The power MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) has been tested for use as a gamma radiation dosimeter by measuring the variation of threshold voltage based on the quantity of dose, and a maximum total dose of 30 krad exposed to a $^{60}Co$ ${\gamma}$-radiation source, which is sensitive to environment parameters such as temperature. The gate oxide structures give the main influence on the changes in the electrical characteristics affected by irradiation. The variation of threshold voltage on the operating temperature has caused errors, and needs calibration. These effects can be overcome by adjusting gate oxide thickness and implanting impurity at the surface of well region in MOSFET.

• 한국가스학회:학술대회논문집
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• 한국가스학회 1997년도 추계학술발표회 논문집
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• pp.229-235
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• 1997

A low power (300 mW) catalytic bead combustible gas sensor is developed and utilized with a computer controlled sampling system for measuring heat content of natural gas. The heat content of gas is proportional to the change in the energy required to exposure to the sample of combustible gas. The heat content of natural gas samples ranging 36.30 - 39.88 MJ/$m^3$ is measured in the range of approximately $1\%$ error, which is comparable to its nominal heat content. Each gas has a slightly different curve of sensitivity vs. sensor temperature. Thus there Is no temperature at which all sensitivities are equal. In calibration process the choice of a optimum operating temperature is an important factor that influences the overall performance of the measurement system.

• 대한기계학회논문집A
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• 제27권1호
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• pp.102-108
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• 2003

Recently, the authors have developed a new material test system fur thin film at the high temperature. It is so compact and precise with sub micron resolution that it seems to be a useful tool fur research of the oxide film growth, its mechanical behavior and failure mechanism. To this end. in this paper three methologies are described for in-situ monitoring of the displacement & strain and the temperature, the oxide thickness. These are the Laser Speckle analysis with digital image correlation technique, the two-color infra-red thermometer and the laser reflection interferometry respectively. The calibration results and some issues which should be addressed for practical application are presented.