• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.521-528
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• 2017

In this paper, the numerical analysis for heat conduction of silica/phenolic composite material, which is used for solid rocket nozzle liner or insulator, was conducted. 1-D Finite Difference Method for the analysis of silica/phenolic during the firing of solid rocket motor was used to calculate the heat conduction considering the surface ablation and the thermal decomposition. The boundary condition at the nozzle wall took into account the convective heat transfer, which was obtained by integration equation. The numerical results of the surface ablation and char depth were compared with the results of test motor that is TPEM-10. It was found that the result of calculation is favorably agreed with the thermal response of test motor.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.22-23
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• 2001

광결정(Photonic crystals)은 유전체를 주기적으로 배치한 구조인데, 이런 구조에 의해 1차원, 2차원, 또는 3차원적으로 빛을 제어할 수 있다. [1] 이런 주기적인 구조로 인해 광결정 내에서는 특정에너지와 특정 방향을 가진 빛이 진행하지 못하는 광밴드 갭(photonic band gap)뿐만 아니라 밴드구조와 밀접한 관계가 있는 비정상적인 광분산이 나타나기도 한다. 이러한 비정상적인 광분산에는 입사빔의 미세한 파장변화에 따른 PC내에서의 급격한 빛의 꺾임이나, 단일 파장의 입사빔이 두갈래로 갈라지는 현상, 또는 negative나 1보다 작은 굴절효과 등이 있는데, 이러한 현상을 해석하기 위한 것으로 광결정내의 고정된 진동수에 해당하는 점들을 2차원 k공간에서 표시한 분산곡선(dispersion surface)이 도입되었다. [2] (중략)

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.1021-1029
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• 1991

본 연구에서는 2차원 정사각형 밀폐공간내에서 흡수 및 방사하는 회기체에 대 한 자연대류-복사 열전달을 P-1 및 P-3 근사법을 이용하고 수치해석을 통하여 유동 및 열전달 특성을 연구하였고 Plank 수, 광학두께 및 벽방사율의 영향을 조사하였다. 또한 P-3 근사해와 비교함으로써 P-1 근사해의 적용범위를 고찰하였다.

• Journal of Biosystems Engineering
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• v.10 no.1
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• pp.48-53
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• 1985

농산물 건조를 위하여 평판형 태양열 집열기를 이용할 경우 가열된 출구공기는 각종 농산물건조적온보다 일반적으로 고온이므로 이의 조절을 위한 출구공기 온도의 예측이 중요시 된다. 본 연구에서는 차원해석법(dimensional analysis)을 이용하여 평판형 집열기의 출구에서 나오는 가열된 공기의 온도를 예측하는 방법이 제시되었으며, 이 방법을 이용하여 집열기의 출구공기온도 예측방정식들이 유량별로 유도되었다. 이 방정식들로부터 구한 출구온도들은 실측한 값들과 잘 일치하였으며($R^2$=0.917~0.957) 또한 집열기의 효율을 나타내는 이론식이 출구공기온도 예측방정식으로 부터 직접 유도되었다.

• Journal of Energy Engineering
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• v.1 no.1
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• pp.76-86
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• 1992

A three-dimensional model has been developed for pulverized coal combusters and gasifiers. Coal devolatilization, heterogeneous char oxidation, gas particle interchange, radiation, gas phase oxidation, primary and secondary stream mixing, and heat losses are considered. A finite difference method was used to solve the ordinary non-linear differential equations. The effects of primary and secondary stream flow ratio and coal particle size are investigated.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.254-259
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• 2001

This study deals with the use of the conjugate gradient method for the simultaneous estimation of two unknown boundary heat fluxes on the slab in reheating furnace. Temperature measurements by the experiment are used in the inverse analysis. The heat flux estimations for three different cases of measurement locations in the slab are performed: non-skid, skid, and shift-skid zones. The estimated heat fluxes for three cases indicated the three regions having local peak values of heat fluxes. The estimated temperatures at measurement locations were in good agreements with the measured temperatures within 5% relative error.

• The Journal of Engineering Geology
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• v.13 no.2
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• pp.171-191
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• 2003

The objective of this present study is to understand long term(500 years) thermohydromechanical interaction behavior on joints adjacent to a repository cavern, when high level radioactive wastes are disposed of within discontinuous granitic rock masses, and then, to contribute this understanding to the development of a disposal concept. The model includes a saturated discontinuous granitic rock mass, PWR spent nuclear fuels in a disposal canister surrounded with compacted bentonite inside a deposition hole, and mixed bentonite backfilled in the rest of the space within a repository cavern. It is assumed that two joint sets exist within a model. Joint set 1 includes joints of $56^{\circ}$ dip angle, spaced 20m apart, and joint set 2 is in the perpendicular direction to joint set 1 and includes joints of $34^{\circ}$ dip angle, spaced 20m apart. The two dimensional distinct element code, UDEC is used for the analysis. To understand the joint behavior adjacent to the repository cavern, Barton-Bandis joint model is used. Effect of the decay heat from PWR spent fuels on the repository model has been analyzed, and a steady state flow algorithm is used for the hydraulic analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.58-65
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• 2004

Thermal and structural finite element analyses were performed for the turbopump turbine bladed disk model with shroud of a liquid rocket engine. The only 1/80 part model was analyzed which consists of 3D eight node isoparametric solid elements. The applied loading history consists of a startup condition with a thermal spike and a steady state. Heat transfer coefficient on the blade was predicted using the commercial Navier-Stokes solver, Fluent. Transient thermal responses during startup and steady states were calculated using a 3D finite element code developed. Maximum stress and shroud tip displacement under the influence of centrifugal and thermal loading were also determined.

• Computational Structural Engineering
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• v.9 no.1
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• pp.101-113
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• 1996

In this paper, the finite element formulation for the thermal analysis of quasi-static, uncoupled, homogeneous, isotropic and linear viscoelastic problems is presented based on the principle of virtual work. The viscoelastic material is assumed to be thermorheologically simple, which is well known material property in a large class of high polymers. The variational formulation and the finite element equation in matrix from are derived. Effective generation and storage of the hereditary stiffness matrices are given in detail especially for the case of the steady state temperature distribution T=T(x). Some numerical examples are given and compared with published results to show the versatility of the derived finite element formulations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.1
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• pp.61-68
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• 2003

This study deals with the use of the conjugate gradient method for the simultaneous estimation of two unknown boundary heat fluxes on the slab in reheating furnace. Temperature measurements by the experiment are used in the inverse analysis. The heat flux estimations for three different cases of measurement locations in the slab are performed: non-skid, skid, and shift-skid zones. The estimated heat fluxes for three cases indicated the three regions having local peak values of heat fluxes. The estimated temperatures at measurement locations were in good agreements with the measured temperatures within 5% relative error.