• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.171-173
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• 1994

Magnetic wedge is proposed for improving the motor performance and to reduce the ripple of air gap flux. Carter's coefficient plays very important role when the ampere turns or exciting current is calculated. In this paper, we calculate the Carter's coe. by FEM taking into account the magnetic anisotropy of magnetic wedge in simple manner and analyze the effect of the wedge. And we analyze the slot leakage flux according to the wedge property.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.722_723
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• 2009

본 논문은 FEM(Finite elements Method)을 활용하여 가로축길이/외경지름 비가 약 2 정도로, 넓적한 평판형 전동기 해석을 할 때 고려해야 할 사항이다. 즉, 오차 발생 요인중의 하나인 축방향 누설을 고려한 해석 방법으로, 이를 위해 2차원해석과 3차원해석을 비교함은 기본이고, 일반적으로 사용하는 방법보다 효율적인 방법을 제안한다. 그후 일반화의 가능 여부와 다른 방안들을 고려하여 본다.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.666-671
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• 2007

To acquire the safety along with durability of mechanical machinery products, we should consider the structural mechanics such as stress, deformation and dynamic vibration characteristics and identify those important aspects in the stage of preliminary design engineering. This cryogenic ball valve is used to transfer the liquified natural gas which temperature is $-196^{\circ}C$, supplied pressure is $168kg/cm^2$. For the cryogenic ball valve, the assurance of structural integrity and operability are essential to meet not only normal, abnormal loading conditions but also functionality during a seismic event. In this thesis, analytical approach and results using finite element analysis and computational method are herein presented to evaluate the aspects of structural integrity along with operability of cryogenic ball valve. In this study, we designed the high pressure cryogenic ball valve that accomplishes zero leakage by elastic seal at normal temperature and metal seal at high temperature.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.10
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• pp.530-536
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• 1999

This paper investigates effects of segmented poles on exciting forces such as cogging torque, BEMF, phase current, torque ripple and local forces. Cogging torque, BEMF and local force are determined by FEM analysis and phase current is calculated using voltage equations after determining BEMF and phase inductance. Effective dead zones at pole separations result in wider than the physical dead zones due to leakage field during magnetization. Due to the existence of dead zones, there exist additional exciting harmonics of the cogging torque which play adverse effect on vibration and noise performance. The magnitude of BEMF is decreased and the waveforms are also distorted depending on dead zone positions. Segmented poles inevitably cause uneven magnetic field distribution at pole separations which introduces additional harmonics of exciting forces which are detrimental to structural to structural resonances. They also decrease motor efficiency by reducing effective phase BEMF.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.38-40
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• 2005

이 논문은 지하매설관의 손상에 따른 자기누설 신호를 유한요소법을 이용하여 Simulation 하고, 자기누설탐사장치를 이용하여 지하매설관에 대한 비파괴검사를 할 경우 나타나는 여러 가지 자기적 신호를 분석하여 손상의 크기나 형상 등을 판별할 수 있도록 기본적인 자기누설정보를 제공하기 위한 연구이다. 3가지 형태의 결함을 배관과의 상대적인 위치에 따라 3차원 FEM으로 해석을 하고 결함의 형상 및 크기대한 정보제공을 위하여 분석을 하였다.

• Journal of Magnetics
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• v.18 no.3
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• pp.297-301
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• 2013

Flux-reversal machine (FRM) is cost effective and suitable for mass production due to its simple structure. However, there is a notable permanent magnet flux leakage which deteriorates the performance. To compensate this drawback with a design method, an Inset-Permanent-Magnet-Type FRM (ITFRM) has been proposed. The ITFRM has permanent magnets perpendicular to the stator teeth surface, and thus, is much more difficult to demagnetize. In this paper, we deal with the iron losses and irreversible permanent magnet demagnetization characteristics of the ITFRM according to various design variables and driving conditions. To analyze the characteristics, a two-dimensional finite-element method (2D-FEM) considering nonlinear analysis of permanent magnets is used. As a result, we propose the design variables that have the largest effects on the iron losses and irreversible magnet demagnetization.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.157-159
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• 1996

For the optimal design of the induction heating cooker, precise and accurate analysis of the magnetic field inside the jar must be achieved first. Until now, design methods based on experience has been used in industry field. But this takes a lot of trial and error, high cost and also long development time. So the analysis of the magnetic field distribution is very important. In this paper the magnetic field inside the induction heating cooker is analyzed by using axisymmetrical FEM(finite element method). And the method of the coil location design for the optimal heat source distribution using sensitivity analysis is developed. In addition, the shielding effect of the non-axisymmetrical 3-D ferrite structure used in induction heating cooker is also analyzed by the integral method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.633-640
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• 2007

In this paper, 3-D reciprocating compressor is taken into flow-structure interaction analysis. The full cycle process consisted of cylinder expansion and compression has been modeled without considering flow leakage through cylinder wall. Fully-coupled FSI analysis of this compressor model was iteratively solved and gives sufficient result with the experimental test. The study is emphasized to thoroughly investigate discharge valve motion, opening and closing, in order to determine discharge valve region which is prone to have high effective stress. The cylinder pressure is successfully validated before conducting impact analyses between discharge valve and other susceptible supported structure. Velocity profile has been obtained in FSI analysis is used as initial condition to carry out further impact analyses. Stress result of discharge valve and valve spring gives preliminary estimation of higher stress area due to its impact phenomena.

• Journal of Advanced Research in Ocean Engineering
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• v.4 no.1
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• pp.7-15
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• 2018

The submarine is an underwater weapon system which covertly attacks the enemy. Pressure hull of a submarine is a main system which has to have a capacity which can improve the survivability (e.g., protection of crews) from the high pressure and air pollution by a leakage of water, a fire caused by outside shock, explosion, and/or operational errors. In addition, pressure hull should keep the functional performance under the harsh environment. In this study, optimal design of submarine pressure hull is dealt with 7 case studies done by analytic method and then each result's adequacy is verified by numerical method such as Finite Element Analysis (FEA). For the structural analysis by FEM, material non-linearity and geometric non-linearity are considered. After FEA, the results by analytic method and numerical method are compared. Weight optimized pressure hull initial scantling methods are suggested such as a ratio with shell thickness, flange width, web height and/or relations with radius, yield strength and design pressure (DP). The suggested initial scantling formulae can reduce the pressure hull weight from 6% and 19%.

• Journal of Korean Association for Spatial Structures
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• v.20 no.3
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• pp.63-70
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• 2020

Tomb of King Muryeong, located in Sonsan-ri, was found vulnerable due to leakages during since the summer of 2016. This research aims to evaluate structural safety of the Tomb under the tumulus. Site surveys were conducted to find vulnerable inner parts. Structural safety assessment is presented based on both site survey results and analytical results obtained through FEM analysis using the ANSYS program. The underground structure was explicitly modeled to focus on two types of loadings: design loads and actual gravity loads. In general, the tomb does not show any critical deflection increase or damage through the analytical investigation. However, maintenance through continuous monitoring is necessary to prevent severe deflections and stress concentrations since the rigidity of the tomb materials are very vulnerable and likely to be reduced due to prolonged weathering and continuous rain leakage.