• 한국광학회지
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• 제23권4호
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• pp.159-166
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• 2012

본 연구에서는 질소와 산소의 회전 라만 신호를 측정하여 낮 시간 온도 측정이 가능한 라이다 시스템을 자체 개발하였다. 태양광에 의한 배경신호를 줄이기 위하여 파장의 폭이 좁고(0.5 nm) 제거율이 높은($10^{-6}$) 회절판과 간섭필터를 이용하였다. 개발된 장치의 성능을 검증하기 위하여 라이다를 수평방향으로 조사하여 온도 특성을 얻고 기상청에서 주어지는 값과 비교하여 상관관계가 일치함을 알 수 있었다. 그리고 수직온도분포로 얻기 위하여 수평으로 얻은 검정 값을 사용하였다. 또한 수직방향으로 조사하여 미국 표준 데이터와 비교하였으며, 존데 데이터와 검정을 통한 본 연구의 결과를 비교하였다.

• 대한기계학회논문집B
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• 제20권10호
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• pp.3334-3343
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• 1996

A quantitative flow visualization technique was developed to measure velocity and temperature fields simultaneously in a two-dimensional cross section of thermo-fluid flows. Thermochromic liquid crystal(TLC) particles are used as temperature sensor and velocity tracers. Illuminating a thermo-fluid flow with a thin sheet of white light, the reflected colors from the TLC particles in the flow were captured simultaneously by two CCD cameras; a 3-chip CCD color camera for temperature field measurement and a black and white CCD camera for velocity field measurement. Variations of temperature field were measured by using a HSI true color image processing system and TLC solution. The relationship between the hue values of TLC color image and real temperature was obtained and this calibration curve was used to measure the true temperature under the same camera and illumination condition. The velocity field was obtained by using a 2-frame PTV technique using the concept of match-probability to track true velocity vectors from two consecutive image frames. These two techniques were applied at the same time to the unsteady thermal-fluid flow in a Hele-Shaw cell to measure the temperature and velocity field simultaneously and some results are discussed.

• 한국물환경학회지
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• 제30권6호
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• pp.673-682
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• 2014

A watershed model was constructed using Hydrological Simulation Program Fortran to predict the water temperature at major tributaries of Nakdong River basin, Korea. Water temperature is one of the most fundamental indices used to determine the nature of an aquatic environment. Most processes of an aquatic environment such as saturation level of dissolved oxygen, the decay rate of organic matter, the growth rate of phytoplankton and zooplankton are affected by temperature. The heat flux to major reservoirs and tributaries was analyzed to simulate water temperature accurately using HSPF model. The annual mean heat flux of solar radiation was estimated to $150{\sim}165W/m^2$, longwave radiation to $-48{\sim}-113W/m^2$, evaporative heat loss to $-39{\sim}-115W/m^2$, sensible heat flux to $-13{\sim}-22W/m^2$, precipitation heat flux to $2{\sim}4W/m^2$, bed heat flux to $-24{\sim}22W/m^2$ respectively. The model was calibrated at major reservoir and tributaries for a three-year period (2008 to 2010). The deviation values (Dv) of water temperature ranged from -6.0 to 3.7%, Nash-Sutcliffe efficiency(NSE) of 0.88 to 0.95, root mean square error(RMSE) of $1.7{\sim}2.8^{\circ}C$. The operational water temperature forecasting results presented in this study were in good agreement with measured data and had a similar accuracy with model calibration results.

• 대한기계학회논문집A
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• 제36권5호
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• pp.513-521
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• 2012

본 연구의 목적은 손상모델의 온도의존성을 고려하여 압력용기강의 취성파괴 거동을 평가하는 것이며, 이를 위해 다중 섬 유전자알고리즘과 와이블 응력모델을 연계하여 대표적 취성파괴 손상모델의 재료상수 결정절차를 개선하였다. 벽개파괴가 예상되는 $-60^{\circ}C$, $-80^{\circ}C$, $-100^{\circ}C$ 온도에서 수행한 SA508 탄소강 재료의 파괴 인성 실험 데이터를 사용하여 개선된 절차에 따른 재료상수를 결정하였고, NUREG/CR-6930과 동일한 결과인 재료상수의 온도의존성을 확인하였다. 최종적으로는 손상모델 재료상수의 온도의존성에 따른 2-매개변수 와이블 응력모델과 3-매개변수 와이블 응력모델의 차이를 정량화하였으며, 공학적으로 활용 가능한 관계식을 제안하였다.

• 한국농공학회논문집
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• 제61권4호
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• pp.23-32
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• 2019

Increasing crop production with the same amount of resources is essential for enhancing the economy in agriculture. The first prerequisite is to understand relationships between the resources. The concept of WEF (Water-Energy-Food) nexus analysis was first introduced in 2011, which helps to interpret inter-linkages among the resources and stakeholders. The objective of this study was to analyze energy-water nexus in greenhouse cultivation by estimating reference evapotranspiration and heating load. For the estimation, this study used the physical model to simulate the inside temperature of the agricultural greenhouse using heating, solar radiation, ventilated and transferred heat losses as input variables. For estimating reference evapotranspiration and heating load, Penman-Monteith equation and seasonal heating load equation with HDH (Heating Degree-Hour) was applied. For calibration and validation of simulated inside temperature, used were hourly data observed from 2011 to 2012 in multi-span greenhouse. Results of the simulation were evaluated using $R^2$, MAE and RMSE, which showed 0.75, 2.22, 3.08 for calibration and 0.71, 2.39, 3.35 for validation respectively. When minimum setting temperature was $12^{\circ}C$ from 2013 to 2017, mean values of evapotranspiration and heating load were 687 mm/year and 2,147 GJ/year. For $18^{\circ}C$, Mean values of evapotranspiration and heating load were 707 mm/year and 5,616 GJ/year. From the estimation, the relationship between water and heat energy was estimated as 1.0~2.6 GJ/ton. Though additional calibrations with different types of greenhouses are necessary, the results of this study imply that they are applicable when evaluating resource relationship in the greenhouse cultivation complex.

• 비파괴검사학회지
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• 제36권6호
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• pp.466-473
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• 2016

선박 건조과정에서 이면부의 도장손상은 용접과정에서 과도한 입열량(heat input)에 따른 전도의 영향으로 손상 방지를 위해서는 용접온도 계측에 의한 적절한 입열량 제어가 필요하다. 온도 계측에는 접촉식, 비접촉식 방법이 있으며 열화상 시스템은 대표적인 비접촉식 방법이다. 하지만 일반적인 열화상 시스템의 탐지센서(detector)는 고온물체에서 방출되는 복사량(radiant quantity)이 과도하면 백화현상(saturation)으로 인해 온도계측이 불가능해진다. 따라서 본 논문에서는 열화상 시스템에 집속되는 과도한 복사량을 차단하기 위해 중성밀도필터(neutral density filter)를 결합하여 고온 물체의 온도를 $3000^{\circ}C$까지 정량적으로 계측하기 위한 복사 에너지 필터링을 연구하였다.

• 동력기계공학회지
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• 제9권2호
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• pp.33-39
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• 2005

Experiments are performed to study the mixed convection flow and heat transfer in an inclined parallel plates with the upper part cooled and the lower part heated uniformly. The Reynolds number ranges from $4.0{\times}10^{-3}\;to\;6.2{\times}10^{-2}$, the angle of inclination, ${\theta}$, from 0 to 45 degree from the horizontal line, and Pr of the high viscosity fluid is 909. In this paper, the PIV(Particle image velocimetry) with TLC(Thermo-sensitive liquid crystal) tracers is used for visualizing and analysis. This method allows simultaneous measurement of velocity and temperature field at a given instant of time. Quantitative data of the temperature and velocity are obtained by applying the color-image processing to a visualized image, and neural network is applied to the color-to-temperature calibration. This paper describes the methods, and presents the quantitative visualization of mixed convection. From this study, it is found that the flow pattern can be classified into three patterns which are affected by Reynolds number and the angle of inclination.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.244-249
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• 2001

In this paper, we present the simultaneous measurement of the fabricaition strain and temperature during and after cure of unsymmetric composite laminate uising fiber optic sensors. Fiber Bragg grating/extrinsic Fabry-Perot interferometric (FBG/EFPl) hybrid sensors are used to measure those measurands. The characteristic matrix of sensor is analytically derived and measurements can be done without sensor calibration. A wavelength-swept fiber laser is utilized as a light source. FBG/EFPI sensors are embedded in a graphite/epoxy unsymmetric cross-ply composite laminate at different direction and different location. We perform the real time measurement of fabrication strains and temperatures at two points of the composite laminate during cure process in an autoclave. Also, the thermal strains and temperatures of the fabricated laminate are measured in thermal chamber. Through these experiments, we can provide a basis for the efficient smart processing of composite and know the thermal behavior of unsymmetric cross-ply composite laminate.

• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.788-796
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• 2017

This paper proposes a new measurement method to improve the shortcomings of an existing integral method for measuring heat flux in plug-type heat flux gauges in the high-temperature and high-pressure environments of liquid-rocket combustors. Using the existing integral measurement method, the calculation of the surface area for the heat flux in the gauge exhibits error in relation to the actual surface area. To solve this problem, transient profiles obtained from ANSYS Fluent were used to calculate unsteady heat flux as it adjusted to the measured temperature. First, a heat flux gauge was designed and manufactured specifically for use in the high-temperature and high-pressure conditions that are similar to those of liquid rocket combustors. A calibration test was performed to prove the reliability of the manufactured gauge. Then, a combustion experiment was conducted, in which the gauge was used to measure unsteady heat flux in a liquid rocket combustor that used kerosene and liquid oxygen as propellants. Reasonable heat flux values were obtained using the gauge. Therefore, the proposed measurement method is considered to offer significant improvement over the existing integral method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.19-24
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• 2003

This paper is to research the heat transfer characteristic in copper-water variable conductance heat pipes(VCHP) with a non-condensable gas and gas reservoir. The heat transfer characteristics in the VCHP have not yet been studied much researches. VCHP are used in many applications. These applications range from thermal control of components and systems on satellites, to precise temperature calibration duties, conventional electronics temperature control and thermal diodes. The practical use of VCHP is a simple way to control the temperature of satellites. As the quantity of NCG was increased, there was an increase in the saturation vapor temperatures. As the input heat has loaded from 90 W to 110 W, the difference of the evaporator surface is lower than $10^{\circ}C$.