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광열변위법을 이용한 반무한 고체의 열확산계수 결정에 대한 이론적 연구
전필수,이광재,유재석,박영무,이종화,Jeon, Pil-Soo,Lee, Kwang-Jai,Yoo, Jai-Suk,Park, Young-Moo,Lee, Jong-Hwa 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.12
A complete theoretical treatment of the photothermal displacement technique has been performed for thermal diffusivity measurement in semi-infinite solid materials. The influence of the parameters, such as radius and modulation frequency of the heating beam and the thermal diffusivity, was studied. Usually, thermal diffusivity was determined by the deformation angle and phase angle as the relative position between the heating and probe beams. In this study, we proposed the simple analysis method based on the real part of deformation gradient as the relative position between two beams. It is independent in the parameters such as power of heating beam, absorption coefficient, reflectivity, Poisson's ratio, and thermal expansion coefficient.
전필수 한국에너지학회 2000 에너지공학 Vol.9 No.2
고체재료의 열확산계수나 열전도계수와 같은 열물성을 비접촉식 방법으로 측정하기 위하여 광열변위법에 대한 이론적인 해석을 수행하였다. 가열빔의 파형을 코사인파, 삼각파 그리고 사각파로 가정하여 2차원 열전도 방정식과 열탄성 방정식의 엄밀해를 구하였고, 이를 가열빔으로부터 직접 구한 실제파의 결과와 비교하였다. 코사인파의 결과가 다른 파형에 비하여 실제파와 가장 유사한 것으로 보아 비교적 해석이 복잡한 실제파를 코사인파로 가정하여도 무방하다.
광열편향법을 이용한 열확산계수 결정에 대한 이론적 연구
전필수,이은호,유재석,목재균,최강윤 한국에너지학회 2001 에너지공학 Vol.10 No.1
재료의 열확산계수를 비접촉적인 방법으로 구하기 위하여 광열편향법에 대한 3차원 모델을 해석하였다. 이 방법은 가열빔이 재료에 광학적으로 흡수될 때 검사빔의 초기궤적이 시편과 시편주의 매질의 온도상승으로 인하여 나타나는 굴절지수의 구배에 의하여 검사빔이 편향되는 원리를 이용하는 것이다. 기존의 연구에서는 주로 가열빔과 검사빔의 상대거리를 변화시키면서 편향의 위상각을 측정하여 열확산계수를 결정하였다. 하지만 본 연구에서는 고정된 상대거리에서 가열빔의 변조주파수를 변화시키면서 편향의 위상각을 계산하여 열확산계수를 구할 수 있는 관계식을 제시하였다. 본 연구에서 제시한 열확산계수 결정 방법은 다른 방법에 비하여 실험과 해석이 간단하고 비교적 측정하기가 어려운 상대거리에 영향을 받지 않는 방법이다.
전필수,이광재,유재석,박영무,이종화,Jeon, Pil-Su,Lee, Gwang-Jae,Yu, Jae-Seok,Park, Yeong-Mu,Lee, Jong-Hwa 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.2
A new method of measuring the thermal diffusivity of solid material at room temperature using photothermal displacement is proposed. The influence of the parameters, such as radius and modulation frequency of the pump beam and the sample thickness, was studied. In previous works, thermal diffusivity was determined by the deformation angle and phase angle as the relative position between the heating and probe beams. In this study, however, we proposed the new analysis method based on the real part of deformation angle as the relative position between two beams. From the zero-crossing position of real part of deformation angle with respect to the pump beam, the thermal diffusivity of the materials can be obtained. The experimental values for different samples obtained by applying the new method are in good agreement with the literature values.
R-404A/POE 오일 혼합물의 기-액 평형과 상용성에 관한 연구
전필수(Pilsoo Jeon),이광재(Kwangjae Lee),유재석(Jaisuk Yoo),김현정(Hyungjung Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The vapor-liquid equilibrium and miscibility measurement apparatus was developed and used to obtain data for refrigerant/oil mixture. The vapor-liquid equilibrium and miscibility data for R-404A/POE22 and R-404A/POE32 oil mixtures are obtained over the temperature range from -20 to 60℃ with 10℃ intervals and the oil concentration range from 0 to 90 wt%. Using the experimental data, an empirical model is developed to predict the temperature-pressure-concentration relations for R-404A/POE oil mixtures at equilibrium. In the R-404A/POE22 oil mixture, the average root-mean-square deviation between measured data and calculated results from the empirical model is 3.56% and in the R-404A/POE32 oil mixture, that is 3.24%. Flory-Huggins theory is also used to predict refrigerant/oil mixture behavior. Immiscibility for R-404A/POE22 oil mixture was observed all over the oil concentrations. Immiscibility for R-404A/POE32 oil mixture was observed at the 10~70 wt% of oil concentrations.
역기구학 모델을 활용한 전기 굴착기의 유압 실린더 위치 제어
전필수(P. S. Jeon),양순용(S. Y. Yang),전용수(Y. S. Jeon),박기서(G. S. Park) 유공압건설기계학회 2022 유공압건설기계학회 학술대회논문집 Vol.2022 No.12
The combination of mechanical, hydraulic, electronic components, and any other modern technology becomes a very complex mechatronics system. At the same time, construction machinery must also meet these expectations regarding durability and ease of operation. This causes time-consuming, malfunctions, and commissioning procedures for equipment manufacturers and suppliers. Their solution is to increase virtual simulator usage in the development precess. In order to complete the simulation, the parameter must be stated in fixed form. In this paper, we will design the virtual hydraulic cylinder model and its parameter for the electric excavator by using least square method.
광열변위법에서 반무한 고체 모델을 이용한 고체재료의 열확산계수 측정
전필수(Pilsoo Jeon),김진화(Jinhwa Kim),김현정(Hyunjung Kim),유재석(Jaisuk Yoo) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
The comprehensive model for the thermal diffusivity measurement using photothermal displacement method was developed. In previous works, the thermal diffusivities for solid metal with a finite sample thickness was determined by comparison between the calculated phase curve and the measured one. Therefore, primary error are caused by the finite sample thickness. In this study, a theoretical and experimental treatment of the photothermal displacement technique has been performed for thermal diffusivity measurement in semi-infinite solid materials. The measurement of thermal diffusivity using semi-infinite solid model have the more accurate value because the thickness effect does not exist. In results, the measured values for a semi-infinite materials have the accordance with the literature values within 1% standard deviation, while those for a finite materials show about 3% one.