• Composites Research
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• v.30 no.5
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• pp.310-315
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• 2017

In this study, we have investigated microstructure, mechanical properties and wear characteristic of aluminum metal matrix composites with a high volume fraction and uniformly dispersed SiC particles which produced by a liquid pressing process. The volume fraction of bimodal SiC/Al7075 composite was 12% higher than that of the monomodal SiC/Al7075 composite and a compressive strength is increased about 200 MPa. As a result of the abrasion test, the wear width and depth of the bimodal SiC/Al7075 composite were $285.1{\mu}m$ and $0.45{\mu}m$, respectively. The coefficient of friction of bimodal SiC/Al7075 was 0.16.

• Journal of Energy Engineering
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• v.10 no.1
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• pp.33-39
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• 2001

석탄화력발전소에 정착되는 고속분립체 이송용 곡관의 내마모성 향상에 관한 수치해석 및 실험적 연구를 수행하였다. 22.5$^{\circ}$와 90$^{\circ}$ 곡관을 모델로 하여, 분립체에 의한 곡관의 마모를 감소시키기 위해 유동방향이 전환되는 부분에 와류장이 형성되도록 곡관의 단면형상을 변화시켰다. 삼차원, 난류유동장의 지배방정식을 유한체적법으로 이산화시키고, SIMPLE 알고리즘을 이용하여 해를 구하였다. 수치해석을 통해 마모감소를 위한 새로운 형상의 곡관을 설계하였다. 새로운 형상의 곡관을 제작, 운전중인 국내 화력발전소에 장착하여 마모실험을 수행하였으며 내마모성이 매우 향상되었음을 알 수 있었다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.3
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• pp.248-254
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• 2009

The worn crater wear geometry of coated tools after machining has been configured by using Confocal Laser Scanning Microscopy(CLSM) and the Wavelet-based filtering technique. The CLSM can be well suited to construct the three-dimensional crater wear on the rake surfaces of coated tips. However, The raw heightness data of HEI(height encoded image) acquired by CLSM must be filtered due to the electronic and imaging noise occurring in constructing the crater image. So the Wavelet-based filtering algorithm is necessary to denoise the shape features in a micro scales so as to realize accurate crater wear topography analysis. The crater wear patterns filtered enable us to predict the crater wear shape in order to study the tool wear evolution. The study shows that the technique by combining the CLSM and Wavelet-based filtering is an excellent one to obtain the geometries of worn tool rake surfaces over a wide range of surface resolution in a micro scale.

• Tribology and Lubricants
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• v.7 no.1
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• pp.61-67
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• 1991

기계평면시일의 접촉 운동면에서 유체가 비압축성이고, 점성의 영향을 받는 경우에 대한 체적누설 유동량과 마찰 토오크를 멱급수의 방법을 이용하여 추정하였다. 본 연구에서 고려되고 있는 설계인자로 시일의 경사도, 접촉 운동면에서의 사인파형, 코우닝, 열탄성 변화량, 마모량, 시일의 스프링 강성도에 따른 축방햐의 변화량을 종합적으로 고려하여 해석하였다. 계산된 결과에 의하면 특히 회전속도가 증가되면 열탄성 변화량에 의한 시일의 누설 마찰 토오크가 커다란 영향을 받고 있는 것으로 나타나고 있다.

• Tribology and Lubricants
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• v.6 no.2
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• pp.34-42
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• 1990

기계명면시일의 접촉 운동면에서 유체가 비압축성이고, 점서의 영향을 받는 경우에 대한 체적 누설 유동량과 마찰 토오크를 멱급수의 방법을 이용하여 추정하였다. 본 연구에서 고려되고 있는 설계인자로 시일의 경사도, 접촉 운동면에서의 사인파형, 코우닝, 열탄성 변화량, 마모량, 시일의 스프링 강성도에 따른 축방향의 변화량을 종합적으로 고려하여 해석하였다. 계산된 결과에 의하면 특히 회전속도가 증가되면 열탄성 변화량에 의한 시일의 누설 유동량과 마찰 토오크는 커다란 영향을 받고 있는 것으로 나타나고 있다.

• Composites Research
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• v.30 no.3
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• pp.209-214
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• 2017

Titanium carbide (TiC) reinforced SKD11 matrix composites were successfully fabricated by a novel liquid pressing infiltration process. Microstructure, mechanical properties, and wear characteristics of the fabricated 60 vol% TiC-SKD11 composite are analyzed. The composite exhibits superior mechanical properties, such as hardness and compressive strength with 24% lower density as compared with SKD11. Improved wear resistance of the TiC-SKD11 composite originates from uniformly reinforced TiC having strong interfacial bonding strength between TiC/SKD11 interface.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.302-307
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• 2004

The major flow-induced vibration mechanisms such as fluid-elastic and turbulence excitation can cause the various types of wear of the steam generator tubes in unclear power plant. It is generally accepted that the tube wear due to vibration is affected by the presence of gap clearance between tube and support plate. Connors showed that the tube wear depth could be estimated by using the relationship between wear volume and sliding distance for contact time. Au-Yang predicted the wear depth by using the nonlinear characteristics of normal work rate to contact time. In this study the effect of gap size on the steam generator tubes wear is analyzed by deriving the wear depth versus normal work rate relationship from these previous results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.919-924
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• 2005

Fretting-wear caused by turbulence excitation for KSNP(Korea standard nuclear power plant) steam generator is investigated numerically. Secondary sides density and normal velocity are obtained by the thermal-hydraulic data of the steam generator. Because nonlinear finite element analysis is complex and time consuming, work rate is estimated by using linear analysis for simple straight 2-span tube. Wear volume and depth by using work rate calculation are estimated. Span length, secondary side fluid density and normal velocity are adopted to study the effects on the fretting-wear by turbulence excitation. When secondary sides density and normal velocity is increased, It turns out that secondary side density and normal gap velocity are very important paramater for fretting-wear phenomena of the steam generator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.475-478
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• 2005

Calculation of wear depth with regard to the wear topology is peformed numerically Four typical wear topology, that is round, crescent, flat, and diamond types are adopted to represent the configuration of wear volume. Diamond and flat types are the most severe topology for wear depth history, whereas round and crescent types have small increasing rate of wear depth to the wear volume. Based on this study we can guess that the most severe wear phenomena happens to be upper side of U-tubes in the KSNP SG, because flat or diamond wear will be generated by the wearing motion between tubes and diagonal, vertical, horizontal strips. The misalignment of tube at the stage of manufacturing or distortion of upper structure due to the thermal expansion or vibration of upper structure such as diagonal, vertical, and horizontal strips will be one of the main causes of flat or diamond wear.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.141-144
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• 2006

In this study, the friction and wear characteristics of pure epoxy and silica-filled epoxy resin composites with average silica particle diameter of $6-33{\mu}m$ were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials against SiC abrasive paper were determined experimentally. The cumulative wear volume tended to increase nonlinearly with increase of sliding distance and depended on diameter of the silica particle for all these composites. The sliding wear tests of the materials demonstrated that the friction coefficient and the wear rate of silica filled epoxy composites were lower than those of the pure epoxy. silica filled epoxy.