• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1993.04a
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• pp.70-79
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• 1993

세라믹은 금속에 비해서 밀도가 낮고, 내마멸성이 우수하고, 열팽창계수가 작고, 높은 온도범위에 걸쳐서 안정성과 경도를 유지함으로 기계구조용재료로서 유망시 되고 있다. 앞으로 세라믹부품에 대한 수요는 더욱 증가하리라고 예상하고 있으며, 세라믹의 응용이 시도되고 있는 부품은 더욱 다양화되어가고 있는 추세이다. 그러나, 세라믹재료에 관한 신뢰할만한 데이터베이스는 확립되지 못한 상태이고, 트라이보시스템에 관한 수명예측과 설계를 위한 기초 자료도 확립하지 못한 상태에 있다. 세라믹재료에 관한 수명예측과 설계를 위해서는 세라믹재료의 트라이보시스템(tribosystem)에서의 마멸기구의 규명과 마멸율을 평가할 수 있는 마멸식을 구하는 것이 가장 기본적인 과제라 할 수 잇다. 따라서 본 연구에서는 최신 기법에 의해서 제조된 HIP제 질화규소와 지르코니아를 실험재료로 하여 무윤활하에서의 미끄럼 마찰$\cdot$마멸실험을 수행하여 마찰$\cdot$마멸특성을 규명하고, SEM을 이용한 마멸면의 미시적 관찰을 통해서 세라믹의 마멸기구를 조사하여 세라믹마멸기구의 마멸모델을 제히하고자 한다. 제시된 마멸모델에 파괴역학을 도입하여 이론해석과 고찰을 수행하여 보다 실용적인 세라믹의 마멸율을 평가할 수 있는 새료운 무차원파라메타를 제안하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.873-878
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• 2016

SCM415 steel for the control valve undergoes wear because of continuous movement between the valve and valve case. The wear of the valve interrupts the performance of the valve, and decreases the service life. In this study, wear characteristics of the as-received and carburized SCM415 steels are evaluated. The wear tests are conducted for various temperatures and loads using a reciprocating wear tester. From these results, wear loss, specific wear rate, and coefficient of friction are analyzed. The wear mechanism was analyzed by SEM. The interaction effects between loads and temperatures on wear loss are determined for analysis of variance using MINITAB.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.3083-3093
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• 1993

Friction and wear at ceramic coated surfaces of aluminum alloy were experimentally studied using a Ring-on-Block wear test machine. Ceramic materials coated on aluminum alloy surfaces were WC, CrC, $Al_{2}O_{3}$ by a plasma spray; and $Al_{2}O_{3}$,$Al_{2}SiO_{5}$, $Na_{2}B_{4}O_{7}$,$Na_{4}P_{2}O_{7}$, and $Al_{2}O_{3}-ZrO_{2}$ composite coating by an Anodic Spark Depositon. They were tested under the sliding wet contact and compared with aluminum alloys and steels. Test results showed that ceramic coated surfaces, in general, have better anti-wear property than those of aluminum alloys due to increase in the surface hardness ; however, they also showed higher coefficients of friction and changes in wear mechanisms, resulting in brittle fractures.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1991.04a
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• pp.68-76
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• 1991

최근 열간압연의 공정이 단순하고 회수율이높은 CC재 (연속 주조재)가 IC재 (Ingot 주조재)에 비해 냉간압연 재료의 주종을 이루고있으며, Roll 조도의 급속한 저하로 슬립현상과 채터링현상 등이 발생한다. 본 연구에서는 Work Roll 마멸 및 조도 저하에 큰 영향을 미치는 (1) 압연 가공길이 및 (2) 실험 재료의 종류에 따른 영향과 (3) 압연하중에 의한 Roll 조도변화를 실제 압연가공을 통하여 분석하고, (4) 알미늄 산화 게재물의 영향과 전사율을 연구하고저 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.274-278
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• 1992

냉간압연기술의 발달로 냉간압연기도 매우 다양하게 발달되었으며 냉간압연의 원자재인 열간압연재의 종류도 다양하다. 최근 열간압연가공시 회수율이 높은 연속주조재(Continuous casting strip)인 CC 재가 종전의 가공과정이 복잡하며 불량율이 높은 Ingot주조재(Ingot casting strip)인 IC 재 보다 생산비율이 점차 증대되어 냉간압연재료의 주종을 차지하고있다. CC재는 냉간압연가공시 IC재에 비해 Work roll 조도저하가 현저하게 크기 때문에 슬립(Slip)과 채팅(Charttering) 현상 등이 발생하여 압연가공성이 불안정 하게 되어 Work roll과 판표면에 손상이 생기게 되고, 압연가공시 Roll 사고 등의 문제가 발생하므로 Roll 마멸의 정도를 파악하여 Roll을 효과적으로 관리하므로써 Work roll과 판표면의 슬립현상 및 채터 링현상 등을 방지할 수 있다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1404-1411
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• 1993

This study was undertaken to investigate the corrosive wear charateristics upon various transformation condition of austempered low-alloy ductile cast iron in corrosive environments against mating specimen made of the hardened SM45C. The corrosive wear test was carried out by rubbing the annular surface of two test pieces in distilled water and aqueous solution at constant sliding speed of 0.5m/s. In severe wear region, the corrosive wear rate Wc increased hastily with NaCl concentration owing to intermetallic adhesion but Wc went down slowly in mild wear region due to lubricating effect of the corrosion product. The critical sliding distance decreased with increasing NaCl concentration due to increased generation rate of the corrosion product and the specific corrosive wear rate has maximum in 1% NaCl aqueous solution at mild wear region. With the variation of matrix, the corrosive wear resistance of the fine acicular bainite was higher than that of coarse upper bainite because of reducing the local cell reaction by carbides. A growth in volume fraction of retained austenite in matrix increased the Wc due to soften surface, but has a declining tendency of Wc in mild wear region.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.8-14
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• 2003

The characteristics of grinding and wear behavior of diamond wheel for grinding ceramic materials was investigated in this study. In case of $Si_3N_4$, the wear of wheel was large, the finding force was relatively stable and the fluctuation of surface roughness n small. On the other hand in case of $Al_2O_3$ and $ZrO_2$, the wear of wheel and surface roughness were decreasing, the grinding force was increasing. During grinding with vitrified bond wheel, $Si_3N_4$ shows renewal of cutting edge while $Al_2O_3$ and $ZrO_2$ show glazing phenomenon of cutting grains. We have found that it possible to observe the behavior of grinding wheel by grinding ratio, grinding resistance, surface roughness and cutting edge ratio. Through the grinding experiments, it was found that grinding life of diamond wheel is 20 times for $Si_3N_4$, and 40 times fir $Al_2O_3$ and $ZrO_2$.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.214-219
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• 1997

The mechanical seals, which are installed in rotating machines like pump and compressor, are generally used as sealing devices in the many fields of industries. The failure of mechanical seals such as leakage, crack, breakage, fast and severe wear, excessive torque, and squeaking results in big problems. To identify abnormal phenomena on mechanical seals and to propose the proper monitoring parameter for the failure of mechanical seals, sliding wear experiments were conducted. Acoustic emission, torque, and temperature were measured during experiments. Optical microstructure was observed for the wear processing after every 10 minute sliding at rotation speed of 1750 rpm and scanning electron microscopy was also observed. Except for the initial part of every experiment, the variation of acoustic emission was well coincided with torque variation during the experiments. This study concludes that acoustic emission and torque are proper monitoring parameters for the failure of mechanical seals. The intensity of acoustic emission signals is measured in root mean square voltage. Temperature of sealing face will be used as a parallel parameter for increasing the reliability of monitoring system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.80-84
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• 1996

This paper aims at reviewing the Possibility application over normal or abnormal, detection used by AE and the wear characteristics of grinding process. In this study, when diamond bur in dentistry with chosen grinding conditions were tuned at grinding. The variation of grinding resistance and hE signal is detected by the use of AE measuring system. The tests are carried out in accordance with diamond burs and workpiece; arcyl and bovine. According to the experiment results, the following can be expected; AE has the possibility to detect the state normality and abnormality. However, the grinding resistance measuring can find it difficult to detect it. It can be accurately excerpted from AE occurrence pattern in contact start point of diamond bur and bovine, grinding condition and derailment point. It is known that AE$\_$rms/ is well compatible with grinding resistance. According to the increase of the material removal rate, the specific energy of the diamond bur is inclined to decrease and the grinding resistance has a tendency to increase.