• Tribology and Lubricants
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• 제38권1호
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• pp.1-7
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• 2022

Chemical-mechanical polishing (CMP) process is a semiconductor process that planarizes a wafer surface using mechanical friction between a polishing pad and a substrate surface during a specific chemical reaction. During the CMP process, polishing pad conditioning is applied to prevent the rapid degradation of the polishing quality caused by polishing pad glazing through repeated material removal processes. However, during the conditioning process, uneven wear on the polishing pad is inevitable because the disk on which diamond particles are electrodeposited is used. Therefore, the abrasion of the polishing pad should be considered not only for the variables during the conditioning process but also when designing the CMP conditioning system. In this study, three design variables of the conditioning system were analyzed, and the effect on the pad wear profile during conditioning was investigated. The three design variables considered in this study were the length of the conditioner arm, diameter of the conditioner disk, and distance between centers. The Taguchi method was used for the experimental design. The effect of the three design variables on pad wear and uniformity was assessed, and new variables used in conditioning system design were proposed.

• 구강회복응용과학지
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• 제30권4호
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• pp.315-323
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• 2014

과도한 치아의 마모는 수직 교합 고경의 감소를 야기하여 구강 및 저작계의 병적 변화를 일으킬수 있으며, 이 경우 새로운 교합 설정과 수직 고경 회복 시 정확한 진단과 분석이 필수적이다. 이에 본 증례에서는 고딕 아치 트레이서를 통해 거상된 수직고경에서의 중심위를 기록한 후 전악 수복을 시행하였다. 본 증례는 70세 남자 환자로서 이가 시리고 아파서 음식을 먹지 못한다는 주소로 내원하였다. 전반적인 치아 마모에 의한 수직고경의 감소를 보여 면밀한 모형분석을 통해 수직고경의 거상을 결정하였다. 거상된 수직고경에 맞춰 고딕 아치 트레이서를 이용하여 중심위 채득 후 임시 보철물을 장착하였다. 4개월 동안 임시 보철물을 통해 적절한 교합을 형성하였으며 이를 이용하여 최종 보철을 제작하였다. 치료를 통해 기능적, 심미적으로 만족할 만한 결과를 얻었기에 이를 보고하는 바이다.

• 대한조선학회 특별논문집
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• 대한조선학회 2013년도 특별논문집
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• pp.66-72
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• 2013

The demand for an ice class ship is rising expected to rise according to the increase of energy consumption and the opening of arctic sea routes. Ice class ship should be designed to cope with the severe environmental conditions of arctic sea such as a high mechanical impact and abrasion damage, caused by pack ice, ice bergs and low temperature. The ice class ship hulls are coated with an anti-abrasion and low friction coating such as a solvent free epoxy or high solid-volume epoxy. These coatings require two-component heating pump and a high grade surface preparation. In this study, the coating performances for the arctic vessels, such as puncture absorbed energy, abrasive wear loss, friction coefficients and impact absorbed energy were evaluated. Based on this study, a proper coating performance specification for the arctic vessels was proposed and coating selection guideline in terms of coating performance and workability was also established.

• Design & Manufacturing
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• 제13권2호
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• pp.44-48
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• 2019

Motor core products are used as materials for electrical steel sheets and cold-rolled steel sheets according to the performance of motors. The cemented carbide material of the mold punch applied to the motor core material causes many troubles due to abrasion and burr problem. The selection of these materials has a great effect on the production life, mass production, product quality as well as mold life. The cemented carbide applied to the products of the motor core is recognized as a very important part. In this study, cold rolled steel sheet was applied to motor core SCP-1 steel 1.0mm, and The effects of abrasion and punching oil on the shear process were investigated for the selection of cemented carbide. Experiments were conducted to select and apply cemented carbide only for the motor core punch optimized for cold rolled steel. The results showed that the cemented carbide material of $CDK3^{***}$ produced the least wear and burrs.

• 구강회복응용과학지
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• 제34권3호
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• pp.137-146
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• 2018

치아 마모로 인해 치아 경조직은 없어지게 된다. 이것은 여러 가지 변수가 작용하는 과정이다. 오랜 시간 동안 치아 마모는 일상적인 임상 영역에서는 별다른 과심을 받지 못하였지만 최근 들어 관심이 점점 더 커지고 있다. 인간의 평균 수명이 계속 늘어가면서 치아의 중요도가 더 증가하기도 하였고 구강 위생이 보편화되고 치과 치료가 발전하면서 치아가 더욱 오랜 동안 구강 내에서 유지되고 있기 때문에 치아 마모가 더 많은 관심을 불러 일으키고 있는 것이다. 치아 마모는 자연적으로 한방향성을 가지고 있기 때문에 이를 통해 개개인의 연령 감정을 하는데 자주 이용되었다. 당연하게도 치아 마모를 이용한 연령감정은 상대적으로 넓은 범주에서 이루어지고 그 정확성도 의심받고 있다. 고대에서 중세시대까지 치아 마모는 아주 심하게 있어왔다. 그래서 치아 마모는 매우 많은 지역에서 연구되어 왔다. 하지만 아직 이런 개개의 연구들이 통합적인 의미 도출로 이어지지는 못하고 있다. 따라서 지금까지의 연구들을 토대로 통합적인 치아 마모의 이해를 위한 세부적인 연구와 접근이 필요한 시점이다.

• 한국결정성장학회지
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• 제16권3호
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• pp.121-126
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• 2006

HVOF thermal spray coating of Co-alloy T800 is progressively replacing the classical hard coatings such as chrome plating because of the very toxic $Cr^{6+}$ ion known as carcinogen causing lung cancer. For the study of the possibility of replacing of chrome plating, the wear properties of HVOF Co-alloy T800 coatings are investigated using the reciprocating sliding tester both at room and at an elevated temperature of $1000^{\circ}F\;(538^{\circ}C)$. The possibility as durability improvement coating is studied for the application to the high speed spindles vulnerable to frictional heat and wear. Wear mechanisms at the reciprocating sliding wear test are studied for the application to the systems similar to the sliding test such as high speed spindles. Wear debris and frictional coefficients of T800 coatings both at room and at an elevated temperature of $1000^{\circ}F\;(538^{\circ}C)$ are drastically reduced compared to those of non-coated surface of parent substrate Inconel 718. This study shows that the coating is recommendable for the durability improvement coatings on the surfaces vulnerable to frictional heat. The sliding surfaces are weared by the mixed mechanisms such as oxidative wear, abrasion by the sliding ball slurry erosion by the mixture of solid particles and small drops of the melts and semi-melts of the attrited particles cavitation by the relative motions among the coating, sliding ball, the melts and semi-melts. and corrosive wear. The oxide particles and the melts and semi-melts play roles as solid and liquid lubricant reducing the wear and friction coefficient.

• 한국표면공학회지
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• 제39권5호
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• pp.240-244
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• 2006

Tribaloy 800 (T800) powder is coated on the Inconel 718 substrate by the optimal High Velocity Oxy-Fuel (HVOF) thermal spray coating process developed by this laboratory. For the study of the possibility of replacing of the widely used classical chrome plating, friction, wear properties and sliding wear mechanism of coatings are investigated using reciprocating sliding tester both at room and at an elevated temperature of $1000^{\circ}F\;(538^{\circ}C). Both at room temperature and at $538^{\circ}C$, friction coefficients and wear debris of coatings are drastically reduced compared to those of non-coated surface of Inconel 718 substrate. Friction coefficients and wear traces of both coated and non-coated surfaces are drastically reduced at higher temperature of $538^{\circ}C$ compared with those at room temperature. At high temperature, the brittle oxides such as $CoO,\;Co_3O_4,\;MoO_2,\;MoO_3$ are formed rapidly on the sliding surfaces, and the brittle oxide phases are easily attrited by reciprocating slides at high temperature through complicated mixed wear mechanisms. The sliding surfaces are worn by the mixed mechanisms such as oxidative wear, abrasion, slurry erosion. The brittle oxide particles and melts and partial-melts play roles as solid and liquid lubricant reducing friction coefficient and wear. These show that the coating is highly recommendable for the durability improvement coating on the surfaces vulnerable to frictional heat and wear.

• Geomechanics and Engineering
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• 제20권5호
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• pp.421-432
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• 2020

Cutting of rocks is very common encountered in tunneling and mining during underground excavations. A deep understanding of rock-tool interaction can promote industrial applications significantly. In this paper, a distinct element method based approach, PFC^3D, is adopted to simulate the rock cutting under different operation conditions (cutting velocity, depth of cut and rake angle) and with various tool geometries (tip angle, tip wear and tip shape). Simulation results showed that the cutting force and accumulated number of cracks increase with increasing cutting velocity, cut depth, tip angle and pick abrasion. The number of cracks and cutting force decrease with increasing negative rake angle and increase with increasing positive rake angle. The numerical approach can offer a better insight into the rock-tool interaction during the rock cutting process. The proposed numerical method can be used to assess the rock cuttability, to estimate the cutting performance, and to design the cutter head.

• 전기학회논문지
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• 제65권5호
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• pp.888-894
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• 2016

In this paper, we describe a method for precisely measuring the abrasion of the railway using an image processing technique. To calculate the wear of the rails, we provided a method for accurately matching the standard rail profile data and the profile data acquired by the rail inspection vehicle. After the lens distortion correction and the perspective transformation of the measured profile data, we used ICP Algorithm for accurate profile data matching with the reference profile extracted from the standard rail drawing. We constructed the prototype of the Rail Profile Measurement System for High-speed Railway and the experimental result on the three type of the standard rail used in Korea showed the excellent profile matching accuracy within 0.1mm.

• 열처리공학회지
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• 제9권4호
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• pp.271-280
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• 1996

This study has been performed to investigate into some effects of power density and traverse speed of laser beam on optical microstructure, hardness and wear characteristics of gray cast iron treated by laser surface hardening technique. Optical micrograph has shown that large martensite and a small amount of retained austenite appear in outermost surface layer with fine martensite in inside hardened zone. Hardness measurements have revealed that the range of maximun hardness value is $Hv=650{\pm}15$ and as the power density increases and the traverse speed decreses, the depth of hardened zone increases due to as increase in input power density. Wear test has exhibited that wear rasistance of laser surface hardened specimen is superier compared to that of untreated specimen under the condition of same load at a given sliding distance, showing that absorption results of an wxidized substance due to a heavy abrasion appear in untreated specimen. The amount of weight loss of laser surface hardened specimen with respect to sliding distance at a given load decreses with increasing traverse speed at a given power density and with increasing power density at a given traverse speed.