• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.433-434
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• 2002

Chemical mechanical polishing refers to a process by which silicon and partially-processed integrated circuits (IC's) built on silicon substrates are polished to produce planar surfaces for the continued manufacturing of IC's. Chemical mechanical polishing is done by pressing the silicon wafer, face down, onto a rotating platen that is covered by a rough polyurethane pad. During rotation, the pad is flooded with a slurry that contains nanoscale particles. The pad deforms and the roughness of the surface entrains the slurry into the interface. The asperities contact the wafer and the surface is polished in a three-body abrasion process. The contact of the wafer with the 'soft' pad produces a unique elastohydrodynamic situation in which a suction force is imposed at the interface. This added force is non-uniform and can be on the order of the applied pressure on the wafer. We have measured the magnitude and spatial distribution of this suction force. This force will be described within the context of a model of the sliding of hard surfaces on soft substrates.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.1042-1045
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• 2005

The wedge type rail clamp has the operating mechanism: First, the jaw pad clamps a rail with small clamping force. Next as the wind speed increases, the clamping force of the Jaw pad Is Increased by the wedge. The initial clamping force of a jaw pad was determined by the clamping angle of a locker. In this study, we carried out the finite element analysis to evaluate the relationship between the clamping angle of a locker and the clamping force of a jaw pad with respect to the design wind speed, such as 2, 4, 6, 8, and 10m/s, we adopted the wedge type rail clamp fur 50tons class container crane with the wedge angle of $10^{\circ}$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.91-92
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• 2007

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.2
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• pp.132-141
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• 1992

The CCITT recommendation X.3, X.20, X.29 and X.25 protocols have been efficiently used in subscriber site for the purpose of using existing C DTE In the ISDN. The Packet Assem-bly /Disasembly (PAD) which covers these protocols can connect C_DTE to the PSDN. The number of C DTE connected to the PAI) Is dependent on the PAD performance. The design of the Traffic Generator (TG) S/W which can measure the PAD performance Is Introduced In this paper.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.153-154
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• 2010

• Electronics and Telecommunications Trends
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• v.25 no.5
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• pp.159-171
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• 2010

iPad는 Apple사가 만든 태블릿 PC 또는 이와 유사한 모바일 디바이스로, iPhone의 기능에 부가하여 iWorks, iBooks, iAd라는 킬러앱을 장착함으로써 모바일 산업 및 기존 산업들의 생산-유통-소비 구조에 큰 변화를 몰고 올 것으로 전망된다. 주요 기관별 2010년 판매 전망이 300~1,000만 대 사이로 다양한 가운데, iPad는 출시 28일 만에 100만 대의 판매를 돌파하면서 Apple사의 i-시리즈 중 가장 빠른 초기 판매속도를 보이고 있다. 그러나 국내에서는 iPad의 시장확산 속도와 영향력이 해외에서만큼 파괴적이지는 않을 것으로 예상된다. 이는 우리나라 모바일 디바이스 이용 환경/문화가 북미-유럽과 다르고, 대기업 중심의 탄탄한 모바일 단말 제조-유통 구조가 구축되어 있으며, 국내에서 iPhone이 시장점유율 변화에 미친 영향력이 미비했다는 점으로 설명할 수 있겠다. 한편, iPad 열풍에 대한 국내 IT 업체들의 대응방안으로는 대안 소프트웨어 플랫폼을 적극 개발하는 전략, Apple사의 플랫폼 주도권을 인정하고 콘텐츠 및 애플리케이션 개발에 주력하는 전략, 그리고 iPad를 모방한 Me-too 제품을 출시하는 전략 등을 고려할 수 있겠다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.499-500
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.1287-1288
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.434-437
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• 2005

Chemical Mechanical Polishing (CMP) has become an essential step in the overall semiconductor wafer fabrication technology. In general, CMP is a surface planarization method in which a silicon wafer is rotated against a polishing pad in the presence of slurry under pressure. The polishing pad, generally a polyurethane-based material, consists of polymeric foam cell walls, which aid in removal of the reaction products at the wafer interface. It has been found that the material removal rate of any polishing pad decreases due to the so-called 'pad glazing' after several wafer lots have been processed. Therefore, the pad restoration and conditioning has become essential in CMP processes to keep the urethane polishing pad at the proper friction coefficient and to allow effective slurry transport to the wafer surface. Diamond pad conditioner employs a single layer of brazed bonded diamond crystals. Due to the corrosive nature of the polishing slurry required in low pH metal CMP such as copper, it is essential to minimize the possibility of chemical interaction between very low pH slurry (pH <2) and the bond alloy. In this paper, we report an exceptional protective coated conditioner for in-situ pad conditioning in low pH Cu CMP process. The protective Cr-coated conditioner has been tested in slurry with pH levels as low as 1.5 without bond degradation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.362-365
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• 2005

Currently Chemical Mechanical Planarization (CMP) has become an essential step in the overall semiconductor wafer fabrication technology. Especially the CMP pad conditioner, one of the diamond tools, is required to have strong diamond retention. Strong cohesion between diamond grits and metal matrix prevents macro scratch on the wafer. If diamond retention is weak, the diamond will be pulled out of metal matrix. The pulled diamond grits are causative of macro scratch on wafer during CMP process. Firstly, some results will be reported of cohesion between diamond grits and metal matrix on the diamond tools prepared by three different manufacturing methods. A measuring instrument with sharp cemented carbide connected with a push-pull gauge was manufactured to measure the cohesion between diamond grits and metal matrix. The retention force of brazed diamond tool was stronger than the others. The retention force was also increased in proportion to the contact area of diamond grits and metal matrix. The brazed diamond tool has a strong chemical combination of the interlayer composed of chrome in metal matrix and carbon which enhance the interfacial cohesion strength between diamond grits and metal matrix. Secondly, we measured real-time data of the coefficient of friction and the pad wear rate by using CMP tester (CETR, CP-4). CMP pad conditioner samples were manufactured by brazed, electro-plated and sintered methods. The coefficient of friction and the pad wear rate were shown differently according to the arranged diamond patterns. Consequently, the coefficient of friction is increased according as the space between diamonds is increased or the concentration of diamonds is decreased. The pad wear rate is increased according as the degree of diamond protrusion is increased.