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열평형적분법에 의한 사다리꼴단면의 직선휜에서의 열전달해석
조종철,조진호,Jo Jong-Chull,Cho Jin-Ho 대한설비공학회 1982 설비저널 Vol.11 No.3
When exact analytical solutions to certain type of heat conduction problems are quite cumbersome or not obtainable, it is important to introduce approximate analytical methods which are simple and useful compared with numerical methods. In this study, therefore, the Heat Balance Integral Method is applied to analysis of steady-state conduction in a straight fin of trapezoidal profile, and the two-dimensional temperature distribution in the fin and the approximate fin efficiency are obtained. Results are compared with those by the one- dimensional analysis and two-dimensional numerical analysis for a wide range of Biot numbers. It is shown that the two-dimensional temperature distribution obtained by the integral method is in good agreement with that by the finite element method at Biot numbers for which the result by the one-dimensional analysis is unreliable.
조종철(Jong Chull Jo),최훈기(Hoon-Ki Choi) 한국전산유체공학회 2002 한국전산유체공학회지 Vol.7 No.3
This paper addresses a numerical method for predicting transient temperature distributions in the wall of a curved pipe subjected to internal laminar thermally -stratified flow. A simple and convenient numerical method of treating the unsteady conjugate heal transfer in non-orthogonal coordinate systems is presented. Numerical calculations arc performed for the transient evolution of thermal stratification in two curved pipes, where 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 for the cases of pipes with thick wall such as safety related-piping systems of nuclear power plant.
Free Vibration Analysis of Perforated Shell Submerged in Fluid
정명조,조종철,Jhung Myung-Jo,Jo Jong-Chull Computational Structural Engineering Institute of 2006 한국전산구조공학회논문집 Vol.19 No.3
물에 잠긴 다공 원통형 쉘의 경우 물에 잠긴 상태로 유한요소해석을 하기에는 거의 불가능하므로 등가물성치를 사용하여야 한다. 다공 평판의 경우 이에 대한 등가물성치를 ASME 코드에서 제시하고 있지만, 다공 원통형 쉘의 등가물성치에 대한 연구는 아직까지 수행된 적이 없다. 따라서 본 연구에서는 유한요소해석을 이용하여 다공 원통형 쉘의 동적 해석에 이용할 수 있는 등가물성치를 제안하였고 그 타당성을 검증하였다. For the perforated cylindrical shell submerged in fluid, it is almost impossible to develop a finite element model due to the necessity of the fine meshing of the shell and the fluid at the same time. This necessitates the use of solid shell with equivalent material properties. Unfortunately the effective elastic constants are not found in any references even though the ASME code is suggesting those for perforated plate. Therefore in this study the equivalent material properties of perforated shell are suggested by performing several finite element analyses with respect to the ligament efficiencies.
Turbulence Induced Fretting Wear Characteristics of Steam Generator Helical Tubes
정명조(Myung Jo Jhung),조종철(Jong Chull Jo),김효정(Hho Jung Kim),윤영길(Young Gill Yune),유선오(Seon Oh Yu) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
This study addresses safety assessment of the potential for fretting wear damages on steam generator helical tubes due to turbulence induced vibration in operating nuclear power plants. To get the natural frequency, corresponding mode shape and participation factor, modal analyses are performed for helical type tubes with various conditions. Special emphases are put on the effects of coil diameter and the number of turns on the modal and fretting wear characteristics of tubes. Also, investigated are the effects of external pressure on the tube modal characteristics as well as the effects of turbulence induced vibration on the fretting wear characteristics of tubes.
[論文] 觸媒에 依한 가솔린機關排氣中 CO와 HC 濃度低減에 關한 實驗的 硏究
조진호(Cho Jin-Ho),서정일(Seoh Jeong-Il),조종철(Jo Jong-Chull) 한국자동차공학회 1982 오토저널 Vol.4 No.1
When an oxidizing catalytic converter which makes use of platium as a catalyst is employed by means of emission control of CO and HC in gasoline engine, the effects of important factors for<br/> the purification efficiency, i.e. engine speed and secondary air rate, on the reduction of CO and HC concentrations in the exhaust gas are studied experimentally.<br/> In the experiment, gasoline and LPG are used as a fuel, and the purification efficiency is cxamined and the results of both cases arc compared with each other.<br/> The experimental results showed that the purification efficiency in the case of LPG is usually higher than that of gasoline, and the optimum values of engin speed and secondary air rate<br/> for maximum purification efficiency exist in common on both cases.