• 한국광학회지
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• 제12권5호
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• pp.394-400
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• 2001

다층 박막에서의 빛의 반사와 흡수 및 열전달 방정식을 수치해석적으로 풀어 광기록매체용 다층 박막의 광학적 특성과 열전달 특성을 알아보고 이 두 특성들을 모두 고려하여 광기록에 적합한 레이저의 출력 및 지속시간, 다층 박막 구조 상수를 제시하였다. 그 결과 레이저는 650 nm 파장을 기준으로 출력 18mW, 지속 시간 60 nm가 적당하였으며 박막 구조 상수는 ZnS-SiO$_2$140nm, Ge-Sb-Te 20 nm, ZnS-SiO$_2$20~30nm, Al-alloy 100~150 nm가 적당하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제29회 추계학술대회논문집
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• pp.72-75
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• 2007

레이저를 steel 표면에 조사하면, steel은 레이저의 복사 에너지를 홉수하여 급격히 가열되어 온도가 증가한다. 이때 steel에서는 phase explosion이 발생하고 shock wave와 플라즈마가 생성된다. 본 연구에서는 이 steel의 후면에 고폭화약을 접해 놓고 레이저 가열에 의한 화약의 점화 현상을 살펴보았다. 이를 위해 heat diffusion equation과 chemical heat release를 사용하였고, 고에너지 물질의 열분해 반응을 위해 3 step global kinetics를 사용하였다. 또한, 계산된 결과는 실험 결과와의 비교를 통해 검증 되었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.43-46
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• 2007

To find out the optimum design of hydrogen storage and supply tank using Metal Hydride (briefly MH) and to make clear the performance characteristics under various conditions are our research purpose. In order to use the low-temperature exhaust heat, $LaNi_{4.7}Al_{0.3}$ which operates under the low pressure of 1MPa is chosen, and we measure the basic properties, namely density, specific heat, PCT(Pressure-Concentration-Temperature) characteristic, and effective thermal conductivity. Then, a numerical calculation model of hydrogen storage using MH alloy is suggested and this thermal diffusion equation of model is solved by the backward difference method. This calculation results rate compared with the experimental results of the systems which installed 1kg MH alloy and, it is found out that our calculation model can well predict the experimental results. By the experimental using MH alloy, it is recognized that the hydrogen flow rate can control by the step adjustment of brine temperature.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.375-379
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• 1997

Pulsed Er:YAG and $CO_2$ lasers induced temperature rise of tissue are studied using axisymmetric, two-dimensional, and transient Pennes' bio-heat equation or the implications of skin resurfacing. Model results indicate that Er:YAG laser induced temperature has much higher but more shallow distribution in tissue than that of the $CO_2$ laser because of its higher absorption coefficient. The increase of repetition rate does not affect the temperature rise too much because these laser modalities have much shorter heat diffusion time than the temporal length of each off-pulse. This model works as a tool to understand the photothermal effect in the laser-tissue interaction.

• Journal of Photoscience
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• 제5권1호
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• pp.39-43
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• 1998

Pulsed Er: YAG and CO$_2$ lasers induced temperature rise of tissue is studied using axisymmetric, two-dimensional, and transient Pennes bio-heat equation for elucidating the implications of skin resurfacing. Modeling indicates that Er:YAG laser induced temperature has much higher but more shallow distribution in tissue than that of the CO$_2$ laser because of much higher absorption coefficient. The increase of repetition rate does not much affect on temperature rise because these laser modalities have much shorter heat diffusion time than the temporal length of each off-pulse. This model works as a tool to understand the photothermal effect in the laser-tissue interaction.

• 한국재료학회지
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• 제1권1호
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• pp.29-36
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• 1991

Pressurized Water Reactor (PWR) pressure vessels are made of forged low alloy steel plates internally clad with an austenitic stainless steel by welding to improve anti-corrosion properties. They display a characteristic behavior of dissimilar metal weld interface during post weld heat treatment (PWHT) and service at high temperature and pressure. In this Study, Metallugical structure of weld interface of SA 508 Class 3 forged steel clad with 309L, Austenitic stainless steel after PWHT was investigated. To estimate the width of the carburized/decarburized bands quantitatively, a model for carbon diffusion was proposed and a theoretical equation was derived.

• 설비공학논문집
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• 제13권9호
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• pp.860-867
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• 2001

Absorption of water vapor into LiBr-$H_2O$ O solution flowing over a finned inclined surface is numerically investigated. The momentum, energy, and diffusion equation are numerically solved using a finite difference method. The four different shapes of the wall surfaces are considered to find the best surface for absorption assuming that the wall temperature and the surface tension are constant. The effects of the fin interval and Reynolds number are investigated. Based on the numerical results, it is known that the parabolic surface shows better absorption performance than the other surfaces, and that water vapor absorption increases gradually with decreasing the fin interval.

• 대한기계학회논문집
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• 제16권2호
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• pp.382-390
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• 1992

The problem of natural convection from a vertical fin is solved by coupling the thermal diffusion equation in the fin to the constitutive equations of the ambient medium involving the radiation of the medium. The analysis is accomplished by employing an integral method. The governing equations for the problem are solved by shooting method based on the Runge-Kutta Scheme at Pr= 0.7. For the range of values of the fin parameter and the radiation-conduction parameter in the analysis, the numerical results show that the radiation effects play an important role in the heat transfer and enhance the heat transfer.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1993년도 추계학술강연 및 발표대회강연 및 발표논문 초록집
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• pp.3-3
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• 1993

In mechanical testing of W-Ni-Pe heavy alloys, the cracks nucleate at W/W interface and propagate through W/ Imatrix interface or through matrix phase together with the cleavage of W grains. The mechanical properties can therefore be improved by control of the interfacial strength and area. In this presentation, some experimental result and techniques on this subject will be reviewed and discussed. The hydrogen embrittlement caused by the hydrogen segregation at interfaces during sintering in an hydrogen atmosphere can be removed by an heat-treattnent in vacuum or in an inert atmosphere. The heat-treatment condition can be estimated by using a diffusion equation for a cylindrical shape. The mechanical properties, in particular the impact property, are degraded by the segregation of non-metallic impurities, such as Sand P. The degradation can be prevented by adding a fourth element, such as La or Ca, active with the non-metallic impurities. The cyclic heat-treatment at usual heat-treattnent tempemture causes the penetration of matrix between W/W grain boundaries and results in remarkable increase in impact energy. This is due to an increase in the area of ductile failure during the impact test. The instability of W/matrix interface casued by addition of Mo or Re can be controlled by using W powders of different size. The increase in the interfacial area in found to be related to the presence of non-equilibrium pure W gmins among W(Mo or Re) solid solution gmins.

• Journal of applied mathematics & informatics
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• 제42권3호
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• pp.607-623
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• 2024

This article studies the effects of heat generation/absorption and thermal radiation on the unsteady magnetohydrodynamic (MHD) Casson fluid flow past a vertical plate through rotating porous medium with constant temperature and mass diffusion. It is assumed that the plate temperature and concentration level are raised uniformly. For finding the exact solution, a set of non-dimensional partial differential equations is solved analytically using the Laplace transform technique. The influence of various non-dimensional parameters on the velocity are discussed, including the effects of the magnetic parameter M, heat generation/absorption Q, thermal radiation parameter R, Prandtl number Pr, Schmidt number Sc, permeability of porous medium parameter, Casson fluid parameter γ, on velocity, temperature, and concentration profiles, which are discussed through several figures. It is found that velocity, temperature, and concentration profiles in the case of heat generation parameter Q, Casson fluid parameter γ, thermal Grashof number Gr, mass Grashof number Gc, Permeability Porous medium parameter K, and time t have retarding effects. It is also seen that the magnetic field M, Thermal Radiation parameter R, Prandtl field Pr, Schmidt number Sc have reverse effects on it.