• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.912-913
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• 2011

본 논문은 Yoke 형상 변화에 따른 EV-Relay 구동 액츄에이터의 동작특성에 대해 연구하였다. 요크는 기본 형상을 포함하여 3가지 형태이며, 각 형상에 대해 유한요소해석으로 동작특성을 계산하였다. 계산시간 단축을 위해 2차원 축대칭 모델을 이용하였고, 기계적 부하를 동작특성 계산과정에 포함하여 실제동작상태와 유사하게 표현하였다. 마지막으로, 요크 형상에 따른 3가지 모델의 계산결과를 비교하여 기존 모델보다 형상이 변화된 모델의 동작특성이 개선되었음을 확인하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.47-55
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• 2018

In order to determine whether three-dimensional effects exist in a pintle nozzle of axisymmetric shape, a three-dimensional numerical analysis was performed. The compressibility correction was implemented with the k-${\omega}$ SST turbulence model to predict the complex flow separation transition in acceptable accuracy. Recirculation zones were observed at both the front end and rear faces of the pintle, and the flow through the pintle nozzle conveyed complex shock wave structures. Three-dimensional effects that resulted from the reasonable flow separation location were noted, and a trace of the transient pressure increase was observed, mismatched by a two-dimensional axi-symmetric analysis.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05b
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• pp.999-1004
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• 1995

본 논문에서는 현재 수행 중인 Hualien 대형내진모델시험 프로젝트의 연구 과제 중의 강제 진동 해석 및 지진 응답 해석을 수행하기 위계서 Hyperelement를 사용한 지반-구조물 상호작용 해석에 대한 절차 및 방법을 연구하였다. Hualien 대형내진모델시험에서 이미 수행된 뒷채움 후 강제 진동 시험의 예 측 및 예측후 해석을 수행하였고, 지진 응답 해석을 위해서는 Hualien부지에서의 자유장해석을 통하여 입력 지반 운동을 결정하여 구조물에서의 지진 응답을 구하였다.

• Transactions of Materials Processing
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• v.5 no.2
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• pp.156-164
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• 1996

To investigate the behavior of plastic deformation in axisymmetric extrusion through square dies, experimental works with the plasticine as a model material are carried out at the room temperature. Some mechanical properties of the model material are determined by compression and ring compression tests. Visioplasticity method using expermental grid distortion in extrusion is introduced to analyze the plastic flow strain rate and strain distribution. In spite of severe deformation during the extrusion through square die the visioplasticity method shows good results for the distribution of effective strain rate and effective strain.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.8
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• pp.1583-1594
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• 1992

A numerical calculation on the flame structure and soot particle distribution in a coannular laminar diffusion flame was performed. Flame analysis model utilized basically flame sheet concepts, Shvab-Zel'dovich assumption, and one step overall irreversible reaction. It was also considered the variation of thermodynamics and transport properties, and the stagnation enthalpy was used for solving temperature field. Radiation was taken into account, since it has been found to be important in determining the flame temperature in sooty flames. For soot particle analysis, we adopted the coagulation, suface condensation, and the oxidation model in addition to tesner's two-step formation model. Equations for primary soot particle excluding the agglomeration process were solved. Based on the results, the regions of soot generation, growth, and oxidation in the flame have been observed and radiation strongly influenced flame temperature and soot distribution.

• The Journal of the Korea Contents Association
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• v.13 no.2
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• pp.505-511
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• 2013

A new boundary treatment technique which can be applied to axi-symmetric topography with inclined bottom was developed. Although the finite element method is good for complex geometry, there is no proper boundary treatment when a boundary is not a vertical section because the water depth at the coastline becomes zero. In this study, we developed a new boundary treatment for inclined bottom using the analytical solution for long wave. To develope a model, the mild-slope equation was used and then, a computational domain is divided into an analytical region and a numerical region. By combining a numerical and an analytical solutions, a complete solution was obtained. The developed solution was validated by comparing with a previous analytical solution.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.2
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• pp.69-78
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• 2009

Cavitating flow simulation is of practical importance for many hydraulic engineering systems, such as pump, turbine, nozzle, injector, etc. In the present work, a solver for cavitating flow has been developed and applied to simulate the flows past axisymmetric cylinders. Governing equations are the two-phase Navier-Stokes equations, comprised of continuity equation of liquid and vapor phase. The momentum equation is in the mixture phase. The solver employed an implicit, dual time, preconditioned algorithm in curvilinear coordinates. Computations were carried out for three axisymmetric cylinders: hemispherical, ogive, and caliber-0 forebody shape. Then, the present calculations were compared with experiments and other numerical results to validate the present solver. Also, the code has shown its capability to accurately simulate the re-entrant jet phenomena and ventilated cavitation. Hence, it has been found that the present numerical code has successfully accounted for cavitating flows past axisymmetric cylinders.

• Journal of the Korean Vacuum Society
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• v.3 no.4
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• pp.457-465
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• 1994

유도결합 플라즈마의 해석식으로 양극성 확산, 정상상태를 가정한 확산식, 열평형식과 변위전류 를 무시한 맥스웰 식을 사용하였다. 해석기법으로는 유한 차분법과 적분법을 축대칭 2차원(R, Z)모델에 적용하였다. 유도 결합 플라즈마장치의 RF 전력, 압력, 석영창 두께, 차폐부 높이에 따른 전자온도, 전자 밀도, 등가 정항 등가 인덕턴스 효율 결합계수 K, Q-factor의 변화를 구하였다. 특히 등가정항은 진공챔 버, 차폐부 및 코일의 손실저항을 고려하여 구하였다.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.854-859
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• 2000

When the round bar with step is twisted and bent, stress concentration is occurred in the irregular geometric parts. Two dimensional axisymmetric stress analysis is carried out according to the geometric change of the stress-concentrated part of round bar with step. Three dimensional cases are also investigated.

• Computational Structural Engineering
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• v.7 no.2
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• pp.11-15
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• 1994

본 고에서는 축대칭회전 Shell을 해석모델로 선정하여 주로 Shell의 휨 강성이 구조체의 거동에 미치는 영향에 대하여 검토하였다. 어떠한 구조형식이든 외력의 작용하에서 발생되는 응력이 축방향력 뿐이라는 것은 상당히 합리적이고 역학적으로도 명쾌한 동시에, 실제 설계상 이상적인 판단기준을 부여하지만, 실제로는 필히 휨상태를 수반하게 된다. 이러한 휨상태는 구성요소의 휨강성에 크게 의존하고 있고, 구조체에 어느정도의 휨강성을 부여하므로써 작용하중에 대한 저항능력의 증가, 변형 및 응력의 저감에 효과적이라는 것을 알 수 있다. 본 고에서는 등방성 Shell에 대한 선형 해석결과만을 게재하였으나, 이러한 성상은 여러가지 영향인자(지지조건, 하중상태 등)에 따라 아주 상이하게 나타나기 때문에 세심한 고찰이 필요하다고 할 수 있다.