• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1763-1773
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• 1991

본 연구에서는 포화수증기와 공기의 혼합기내에서 분무수적으로의 열 및 질량 전달률을 계산하기 위하여 수적의 부분혼합모형과 비혼합모형에 대하여 수적내 과도온 도분포의 해석해를 적용성이 보장되면서도 계산상의 어려움이 수반되지 않는 형태로 구하기 위하여 수적내부의 열전도해석에 있어서 적분법을 적용하였다. 적분법으로 얻어지는 과도온도분포의 해는 유한차의 다항식으로 표시되어 비혼합모형인 경우 각시 간 구간의 경계에서의 온도분포가 연속성을 유지하면서 물성치들의 온도에 대한 종속 성이 쉽게 고려되고 계산도 용이한 형태이다. 본 보에서 제시하는 해석결과의 적용 성을 조사하기 위하여 완전혼합모형을 포함하는 세가지 수적모형들에 대한 계산결과들 로부터 얻어진 시간변화에 따른 수적의 무차원 체적평균온도변동을 유효한 실험결과들 과 비교, 검토하였으며, 부분혼합모형에 대하여 혼합기의 압력, 수적의 초기온도, 혼 합기 속에 포함되어 있는 수증기의 체적분율, 수적의 초기크기, 수적의 초기속도 및 분사각도가 주위혼합기로부터 수적으로 전달되는 열 및 질량전달에 미치는 영향을 조] 사하고 도출된 대표적인 검토 결과를 제시하였다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.3
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• pp.191-203
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• 1992

To analyze the unsteady heat transfer phenomena in radiant heating panel, a mathematical model was considered. Numerical analysis for solving the governing equations was conducted by using the finite difference method with boundary-fitted meshes. Transient temperature distributions and thermal responses in heating panel were obtained for various design parameters such as pipe pitches, pipe diameters and pipe depths. Experimental results were also obtained to verify the results of calculation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.211-218
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• 2002

It has been investigated for the temperature profile in a planar evaporator of micro-cooler subject to a uniform heat flux prior to tole initiation of boiling. The results of the analysis allow for the determination of applied power levels fur which nucleation is likely to occur only within the vapor grooves of the evaporator while maintaining subcooling in the liquid core, thereby increasing the likelihood of a successful startup. Also, limits are fecund for which additional increases in the applied heat flux do not increase the temperature difference between the vapor grooves and the wick-liquid core interface. This analysis is appropriate for the microscale evaporators of micro-cooler during a fully-flooded startup as well as starter pump designs and micro-CPLs(capillary pumped loops). The results are useful in the initial basic design of microscale heat transfer devices.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.252-259
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• 2001

It is derived for the temperature profile in a cylindrical and planar shape capillary pumped loop evaporators subject to a uniform heat flux prior to the initiation of boiling using the finite difference method. The results of the analysis allow for the determination of applied power levels for which nucleation is likely to occur only within the vapor grooves of the evaporator while maintaining subcooling in the liquid core, thereby increasing the likelihood of a successful startup. Also, limits are found for which additional increases in the applied heat flux do not increase the temperature difference between the vapor grooves and the wick-liquid core interface. Several advantages of larger diameter evaporators observed experimentally in startup are explained and quantified by the model. This analysis is appropriate for standard capillary pumped loop evaporators during a fully-flooded startup as well as starter pump designs and loop heat pipes.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.772-779
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• 2019

The subsea pipeline has received considerable attention as a high-value-added industry linked to the energy and steel industries including natural resource development. The design and installation of the subsea pipeline require a variety of key technologies to carry out the project. In particular, a thorough pre-verification process through pre-commissioning is essential for the safe operation of the subsea pipeline. The hydrotesting stage in the pre-commissioning process of the subsea pipeline is known to be affected significantly by the ambient temperature change; however, there is a little study based on the theoretical and numerical approach. In this study, the method of predicting the internal temperature change using the transient heat transfer method for the stage of hydrotesting during the pre-commissioning process of the subsea pipeline and the prediction method of the pressure variation in the pipeline using it were proposed. The predicted results were compared with field test results and its effectiveness was verified. The proposed analysis procedure is expected to contribute to the productivity improvement of the subsea pipeline installation project by enabling the prediction of pressure variation through pipeline heat transfer simulation from the initial design stage of the subsea pipeline installation project.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.92-98
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• 2006

An 1 lbf of NASA standard monopropellant thruster, MRE-1, is used for KOMPSAT (Korea Multi-Purpose Satellite) which is launched in 2006 and provides reliable and cost-effective means for attitude and maneuvering control system. The monopropellant thruster obtains required thrust by thermal decomposition process of propellant through catalyst bed. During firing, the decomposition plays a role of a heat source that may occur an excessive radiation heat transfer to peripheral structures and electronics in relatively low temperature condition.Therefore, the radiation heat shield is needed to prevent the critical radiative heat exchange between thruster and satellite during firing. This paper summarizes an overall development process of radiation heat shield from the design engineering up to the manufacturing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.455-459
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• 2000

신경의 기본단위인 뉴런을 계층 구조형태로 연결하여 자극에 대한 각 뉴런의 신경전달 메카니즘을 분석하고 Na 이온의 값을 변형시켜 활성전위에 미치는 영향을 LINUX를 기초로 한 GENESIS를 이용하여 시뮬레이션을 해 보았다. 뉴런은 미세한 자극뿐만 아니라 이온농도의 변화로 인한 매우 민감하게 반응함으로 신경의 활성전위와 인체를 구성하는 모든 세포에서의 이온농도의 중요성을 간과해서는 안 된다. 본 연구에서는 신경세포를 전기회로 적인 모텔을 기준으로 설계하였으며, 농도의 변화에 의해 활성전위 전달에 큰 변화를 일으켰다. 과대한 농도 변화는 신경에서의 과도한 활성전위와 매우 낮은 전위가 발생함을 알 수 있었다. 이로 인해 인체에 미치는 영향은 신체의 어느 부분이냐에 따라 다르겠지만 뇌에서의 열, 뇌 세포 손상, 근육마비, 심장마비 등의 이상 현상을 추정할 수 있을 것이다.

• Solar Energy
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• v.17 no.3
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• pp.13-21
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• 1997

In this study, the theoretical equation of thermal storage efficiency was established to applied long term hot water storage system. The, effective thermal diffusivity and storage efficiency were, measured through the experiment to predict the degree of mixture in thermal storage tank. The effective thermal diffusivity was inversely preportional to the storage efficiency. The most effective storage efficiency was obtained under condition of low flow rate and using the perforated distributor.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.474-481
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• 2001

This paper addresses a numerical method for predicting transient temperature distributions in the wall of a curved pipe subjected to internally thermal stratification flow. A simple and convenient numerical method of treating the unsteady conjugate heat transfer in the non-orthogonal coordinate systems is presented. The proposed method is implemented in a finite volume thermal-hydraulic computer code based on a cell-centered, non-staggered grid arrangement, the SIMPLEC algorithm, a higher-order bounded convection scheme, and the modified version of momentum interpolation method. Calculations are performed for the transient evolution of thermal stratification in two curved pipes, where the one has thick wall and the other has so thin wall that its presence can be negligible in the heat transfer analysis. The predicted results show that the thermally stratified flow and transient conjugate heat transfer in a curved pipe with a finite wall thickness can be satisfactorily analyzed by the present numerical method, and that the neglect of wall thickness in the prediction of pipe wall temperature distributions can provide unacceptably distorted results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.729-732
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• 2010

The present study has been motivated by the development of a reliable numerical methodology for simulation of kerosene/LOx coaxial swirl injectors. To deal with thermodynamic non-ideality and anomalies of transport properties pronounced at supercritical pressures, a set of subroutine libraries has been constructed based on the cubic equations of state, and applied to an existing flamelet analysis code. For computational efficiency, two-dimensional axisymmetric RANS formulation with swirl was adopted and validated successfully against an isothermal coaxial swirling jet. For the actual problem with high pressure combustion, however, numerical results show that the RANS models yield excessive production of turbulence probably due to high density gradient magnitude in the vicinity of mixing layer of swirling film flow, and imply strongly further improvement of the turbulence models.