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Chemical Mechanical Polishing 공정에 관한 원자단위 반응 모델링
변기량,강정원,송기오,황호정,Byun, Ki-Ryang,Kang, Jeong-Won,Song, Ki-Oh,Hwang, Ho-Jung 한국전기전자재료학회 2005 전기전자재료학회논문지 Vol.18 No.5
This paper shows the results of atomistic modeling for the Interaction between spherical nano abrasive and substrate In chemical mechanical polishing processes. Atomistic modeling was achieved from 2-dimensional molecular dynamics simulations using the Lennard-jones 12-6 potentials. We proposed and investigated three mechanical models: (1) Constant Force Model; (2) Constant Depth Model, (3) Variable Force Model, and three chemical models, such as (1) Chemically Reactive Surface Model, (2) Chemically Passivating Surface Model, and (3) Chemically Passivating-reactive Surface Model. From the results obtained from classical molecular dynamics simulations for these models, we concluded that atomistic chemical mechanical polishing model based on both Variable Force Model and Chemically Passivating-reactive Surface Model were the most suitable for realistic simulation of chemical mechanical polishing in the atomic scale. The proposed model can be extended to investigate the 3-dimensional chemical mechanical polishing processes in the atomic scale.
한태송(Tae-Song Han),이재빈(Jae-Bin Lee),박창용(Chang-Yang Park),허남수(Nam-Su Huh),송기오(Ki-Oh Song),하승우(Seung-Woo Ha),전현익(Hyun-Ik Jeon) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
The optimization of foil shapes in metallic thermal insulation is one of important issue to increase the efficiency of the metal insulation for nuclear power plant. In this study, the equivalent thermal circuit using thermal resistance method was applied to determine the shape of foils in metallic thermal insulation. Three different foil shapes were considered for assessing the insulation performance by using thermal resistance method. Furthermore, two-dimensional CFD analysis was performed for the three shapes to verify the proposed equivalent thermal circuit and evaluation results. The optimum shape of foil in metallic thermal insulation by thermal resistance method was identical to the result by the detailed CFD analysis. Thus, it was verified that the evaluation procedure using thermal resistance method could be acceptable for a qualitative assessment step.
수직으로 설치된 비균질 평판 단열재용 성능시험장치 개발
오홍영(Hong Young Oh),송기오(Ki O Song),전현익(Hyun Ik Jeon),조선영(Sun Young Cho) 대한설비공학회 2016 설비공학 논문집 Vol.28 No.4
In case of metal insulation, which is produced by stacking stainless steel sheets and air layers in a multi-stack manner at a specific thickness, insulation performance will be evaluated based on thermal transmittance rather than the intrinsic physical properties of each material such as thermal conductivity. However, there is no standard for measuring thermal transmittance targeted for non-homogeneous insulation which is used in relatively high temperature conditions such as a power station. In this study, the thermal conductivity of homogeneous insulation acquired by the standardized guard hot plate method and the thermal conductivity of homogeneous insulation measured by the newly developed performance tester were compared to verify the confidence level of the tester. As a result, thermal conductivity acquired by the newly developed thermal transmittance tester was about 6% higher than the thermal conductivity measured by the existing guard hot plate method under the anticipated service temperature conditions.
비접촉식 진동센서를 통한 균열 모사 실험 시편의 진동 특성에 관한 연구
오홍영(Hong-Young Oh),조선영(Sun-Young Jo),하승우(Seung-Woo Ha),송기오(Ki-O Song),이용구(Yong-Gu Lee),이재민(Jae-Min Lee),손진국(Jin-Guk Son) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Recently, there has been a growing interest in the safety of nuclear power plants after the Fukushima nuclear accident. Most of the nuclear accidents occur in small bore pipe welds. Most of the small bore pipe welds which are dangerous are located in the high radiation exposure area. Therefore, there is a problem that the high radiation exposure of the workers is inevitable at the time of installation and replacement, and the current small bore pipe welds are not monitored. Therefore, in this study, we try to confirm the vibration characteristics according to the depth of cracks in the test piece simulating the small diameter pipe weld. In the experiment, the resonance region of the specimen was changed according to the crack depth. Experimental results show that the resonance region moves uniformly depending on the presence or absence of cracks. However, it was confirmed that it does not vary linearly with the crack depth. In the next study, we try to simulate an actual small diameter welded joint.
이재민(Jae Min Lee),송기오(Ki O Song),오홍영(Hong Young Oh),이용구(Yong Gu Lee),하승우(Seung Woo Ha),조선영(Sun Young Cho),최은수(Eun Soo Choi) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
In order to apply a smart damper using polyurethane rubber spring to power plant facilities, it is necessary to consider the environmental temperature at the location where the damper is installed. Therefore, in this study, we study the characteristic change of polyurethane rubber springs according to temperature by hardness measurement and behavior test at various temperature. For the temperature characteristics experiment, two types of cylinder shaped polyurethane rubber springs with different outer diameters were fabricated, and hardness measurement, precompessed and dynamic behavior tests were performed with temperature. As a result of the precompressed and the 5Hz dynamic behavior test at 115℃, rigid body load and load bandwidth were reduced by the plastic deformation. The using limit temperature of the polyurethane rubber spring analyzed by the experimental results is estimated to be below 85℃.