• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.643-648
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• 2011

Fatigue crack in most rails take place by rolling contact between wheel and rail in railway industry. Therefore, it is critical to understand the rolling contact phenomena, especially for the three-dimensional situation. In this paper the steady-state rolling contact problem of KTX wheel and rail (UIC60) has been studied with three-dimensional finite element analysis. The variation of contact pressure and contact stresses on rolling contact surface were obtained using the finite element method. The three-dimensional distribution of contact stresses on the contact surface are investigated. Results show that the distribution of shear stress and contact stress (von Mises) on the contact surface varies rapidly as a result of the variation of stick-slip region. The contact stress at the leading edge is greater than at the trailing edge because of stick and slip phenomena.

• 한국표면공학회지
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• 제46권3호
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• pp.133-138
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• 2013

We have developed a 2D axi-symmetric numerical model for an inductively coupled plasma system in order to analyze gas mixing effect through a narrow gap shower head. For frictional flow, holes of 0.5 mm diameter and 2 mm length are approximately modeled in 2D. Gas velocity distribution 10 mm below the shower head showed 2 times difference between the center and the edge at 10 mTorr. At 10 mm above the wafer, it was increased to 6 times difference due to the pumping duct effect. The model with a 5 mm height buffer region of a shower head showed reasonable behavior of Ar discharge. The density of Ar metastable showed additional peak inside the buffer region around the edge holes.

• 대한기계학회논문집
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• 제17권5호
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• pp.1218-1226
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• 1993

본 연구에서는 기존의 점진균열법을 개량하여 원판의 잔류응력 분포를 측정하기 위한 새로운 방법을 제시하였으며 이것의 타당성을 입증하기 위한 유한요소 해석(finite element analysis)과 실험을 수행하였다.

• 한국공작기계학회논문집
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• 제12권3호
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• pp.89-95
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• 2003

This research analyzes the cutting mechanism of A1100-H18 of commercially pure aluminum by image processing in SEM(Scanning Electron Microscope) for the measurement of strain rate distribution near a cutting edge in orthogonal micro-cutting. The distribution is measured using various methods in order. The methods are in-situ observations of cutting process in SEM, inputting image data, a computer image processing, calculating displacements by SSDA(Sequential Similarity Detection Algorithm) and calculating strain rates by FEM. The min results obtained are as follows: (1)It enables to measure a microscopic displacement near a cutting edge. (2) An application of this system to cutting process of various materials will help to make cutting mechanism clear.

• 동력기계공학회지
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• 제20권4호
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• pp.5-11
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• 2016

This study analyzed the damage to a slitting knife after cutting steel sheets. Damages to the structure were observed and wear tests were conducted. In addition, the degradation on the damaged and undamaged parts was compared with a micro Vickers hardness test. Weibull statistical analysis was carried out in order to evaluate the reliability of the micro Vickers hardness measured data. Spalling of the edge portion occurred by degradation during use over a long period. Rough parts in the specimens were caused by damage because the slitting knife was used for 1 year. The friction coefficient and wear loss at the damaged parts of the knife edge were slightly larger from shock due to repetitive cutting operation. The micro Vickers hardness followed a two-parameter Weibull probability distribution.

• 대한기계학회논문집
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• 제18권6호
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• pp.1559-1566
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• 1994

Using the finite element method, the contact force, contact band width and temperature distribution of lip seals analyzed for the interference including some nonlinearities such as material nonlinearity, geometrical nonlinearity and nonlinear contact boundary condition. The calculated results showed that the contact stress concentrated on the contact zone between the garter spring and the rubber toward the flex side, the contact edge of lip seals. The high contact forces due to the increased interference separate the sealing gap between the lip edge and the rotating shaft. This may lead to leak the sealed oil.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1794-1796
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• 1996

In order to evaluate the soundness of 10 year service-aged XLPE-insulated 22.9 kV underground distribution cables, semiconductive shields have been characterized. The edge of insulation near the insulation shield shows a drastic decrease of OIT. Impurities such as Ca, Mg, Fe, Cu were detected in both conductor and insulation shields. Their concentrations at the insulation shield are much higher than those at the strand shield. All these facts suggest that the edge of insulation near the insulation shield is degraded considerably, which might be attributed to the oxidation reaction of insulation by a large amount of impurities in the insulation shield.

• Tribology and Lubricants
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• 제28권6호
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• pp.272-277
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• 2012

Finite element analysis was carried out using wafer-scale and particle-scale models to understand the mechanism of the fast removal rate(edge effect) at wafer edges in the chemical-mechanical polishing process. This is the first to report that a particle-scale model can explain the edge effect well in terms of stress distribution and magnitude. The results also revealed that the mechanism could not be fully understood by using the wafer-scale model, which has been used in many previous studies. The wafer-scale model neither gives the stress magnitude that is sufficient to remove material nor indicates the coincidence between the stress distribution and the removal rate along a wafer surface.

• 한국안전학회지
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• 제13권3호
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• pp.119-125
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• 1998

In long vertical duct, the aspect of second flame in laminar flame propagating through lycopodium-air mixtures and the behavior of dust particles in neighborhood in front of flame have been examined experimentally. In order to trace the development of second flame to its origin, the velocity and vorticity distribution of dust particles in front of flame were measured by using with the real-time PIV system. The velocity of particles was approximately zero at the central part of flame front and the ahead of the flame leading edge, but maximum near the duct wall. The flame velocity of second flame and the movement of leading flame edge depend mainly on behavior of dust particles by the flow distribution of temperature and pressure.

• 한국산학기술학회논문지
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• 제20권5호
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• pp.569-576
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• 2019

PSC-Edge 거더 라멘교는 Edge 거더에 긴장력을 도입하고 정모멘트를 감소시켜 저형고와 장경간화가 가능한 교량이다. 본 교량은 가설벤트가 상부슬래브의 하부에 지지되고 Edge 거더부에 2차 강연선이 긴장된 후 거더 외측 면에 $45^{\circ}$방향의 사인장 균열이 발생하였다. 프리스트레스 정착부의 응력분포 및 파열균열의 양상에 관한 연구가 활발히 진행되었지만 기존 연구 결과는 본 구조물의 실제 형상과 경계조건이 상이하여 명백한 원인분석이 어려운 실정이다. 따라서 본 논문에서는 가설벤트의 경계조건을 추가로 고려된 3D Frame 해석을 수행하였으나 Edge 거더부에서 최대 압축응력이 발생하여 균열을 원인을 규명하기에는 한계가 있었다. 따라서 LUSAS 16.1을 사용한 3D Solid 해석을 수행하였으며 그 결과 Edge 거더의 하부와 상부슬래브의 경계부분에서 최대 주인장응력이 발생하였다. 최대 주인장응력과 방향여현을 사용하여 둔각부 Edge 거더 외측면의 소요 철근량을 분석한 결과 사용 철근량이 부족한 것으로 분석되었다. 따라서 추가 시공된 교량은 기존 교량보다 정착부의 철근량과 철근보강 범위를 확장시켰다. 그 결과 Edge 거더부의 균열은 더 이상 발생하지 않는 것으로 관찰되었다. 이와 유사한 PSC-Edge 거더 형식의 교량을 설계 및 시공할 때 본문에서 제안한 해석 및 보강방법을 적용하면 시공 중 발생하는 Edge 거더 외측면의 균열을 충분히 제어할 수 있을 것으로 기대된다.