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Chuljin Park,김형재,Hanchul Cho,Taekyung Lee,김도연,Sangjik Lee,Hae-Do Jeong 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.6 No.2
Many studies have looked at the chemical mechanical polishing (CMP) process of sapphire substrates. However, the research on the processing mechanism of the sapphire substrate is insufficient compared with semiconductor CMP processing. This paper focuses on the effect of the slurry pH on the removal rate of sapphire substrate in CMP. When the pH of the slurry is changed, the possible factors that can influence removal rate of sapphire include the zeta potential, abrasive agglomeration, and hydration reaction layers. The colloidal silica slurry used in this study did not show aggregation at any pH value. However, the zeta potential between the abrasive and the substrate changed remarkably at acidic and basic pH. The attractive force between the abrasive and substrate in acidic conditions is higher than that in basic conditions due to the relative surface charge. A higher attractive force caused by opposite charges makes more of the abrasive participate in the polishing process, which increases the removal rate in acidic conditions. However, the removal rate in basic conditions is higher than that in acidic conditions despite the repulsive relative charges. The reason for the higher removal rate in basic conditions seems to be the easier formation of a hydration layer, which is caused by the higher concentration of [OH]− in basic conditions. If the hydration effect is negligible, then the removal rate strongly depends on the magnitude of relative surface charges, which can be defined by the product of the zeta potentials of the abrasives and the substrate. If the product of the potentials is large, the probability of contact between the abrasives and the substrate is increased. Thus, the removal rate is increased. However, if the hydration layer forms, it plays a dominant role in determining the removal rate.
미세절삭력 측정을 위한 다이아몬드 Tool Holder 설계
정상화,김상석,도철진,김건희,유병주 한국공작기계학회 2000 한국공작기계학회 추계학술대회논문집 Vol.2000 No.-
A tool holder system has been designed to measure cutting forces in diamond turning. This system includes a 3-component piezo-electric tranducer. In this research, tool holder system is modeled by considering the element dividing, material properties, and boundary conditions using MSC/PATRAN. Mode and frequency analysis of structure is simulated by MSC/NASTRAN, for the purpose of developing the effective design. In addition, tool holder system is verified by vibration test using accelerometer. This system will aid to the development of Fast Tool Servo (FTS)
염화칼륨 농도에 따른 사파이어 기판 CMP에 관한 연구
박철진(Chuljin Park),김형재(Hyoungjae Kim),정해도(Haedo Jeong) 한국트라이볼로지학회 2017 한국윤활학회지(윤활학회지) Vol.33 No.5
Chemical Mechanical Polishing of chemically stable sapphire substrates is dominantly affected by the mechanical processing of abrasives, in terms of the material removal rate. In this study, we investigated the effect of electrostatic force between the abrasives and substrate, on the polishing. If potassium chloride (KCl) is added to slurry, water molecules are decomposed into H+ and OH− ions, and the amount of ions in the slurry changes. The zeta potential of the abrasives decreases with an increase in the amount of H+ ions in the stern layer; consequently, the electrostatic force between the abrasives and substrate decreases. The change in zeta potential of abrasives in the slurry is affected by the slurry pH. In acidic zones, the amount of ions bound to the abrasives increases if the amount of H+ ions is increased by adding KCl. However, in basic zones, there is no change in the corresponding amount. In acidic zones, zeta potential decreases as molar concentration of potassium increases; however, it does not change significantly in basic zones. The removal rate tends to decrease with increase in molar amount of potassium in acidic zones, where zeta potential changes significantly. However, in basic zones, the removal rate does not change with zeta potential. The tendencies of zeta potential and that of the frictional force generated during polishing show strong correlation. Through experiments, it is confirmed that the contact probability of abrasives changes according to the electrostatic force generated between the abrasives and substrate, and variation in removal rate.
Studies on the Manufacture Properties of SPC (Sulfur Polymer Cement) Concrete using Coal Bottom Ash
Bumui Hong,Chuljin Jeong,Changsik Choi 한국폐기물자원순환학회 2015 한국폐기물자원순환학회 학술대회 Vol.2015 No.05
In this work, we constructed the sulfur polymer cement(SPC) concrete using coal bottom ash from 4 thermal power stations in korea and investigated their practical data for production of industrial construction compounds. To manufacture the SPC concrete, we used batch concrete mixer with the heating jacket using hot oil. Also, coal bottom ash was used as a fine aggregate below 2 mm. When the SPC concrete were produced with diverse sulfur concentration (15, 20, 25, 30 wt%), compressive strength properties were analyzed. We got the compressive strength of the maximum 60 MPa. These experimental results could be effectively applied to the recycling technology of coal bottom ash.
Studies on the Liquid Carbonation using Recycled Aggregates
Bumui Hong,Chuljin Jeong,Changsik Choi,Jinwon Park 한국폐기물자원순환학회 2015 한국폐기물자원순환학회 학술대회 Vol.2015 No.05
In this study, we examined the liquid carbonation reaction using recycled aggregates as an industrial by-products. This research deals with carbon fixation with a precipitation reaction utilizing 5 wt% and 30 wt% alkanolamine absorbents in an aqueous calcium oxide solution. Unlike carbon fixation operated at high temperature and pressure that consumes a lot of energy, we conducted experiments at moderate temperature (303.15 K) and pressure (1 atm). By adding calcium oxide solution into the carbon dioxide saturated solution, carbonated recycled aggregate was formed. To verify the physical properties of products, XRD analysis was performed and SEM images were obtained.
Studies on the Liquid Carbonation using Recycled Aggregates
( Bumui Hong ),( Chuljin Jeong ),( Changsik Choi ),( Jinwon Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2015 No.-
In this study, we examined the liquid carbonation reaction using recycled aggregates as an industrial by-products. This research deals with carbon fixation with a precipitation reaction utilizing 5 wt% and 30 wt% alkanolamine absorbents in an aqueous calcium oxide solution. Unlike carbon fixation operated at high temperature and pressure that consumes a lot of energy, we conducted experiments at moderate temperature (303.15 K) and pressure (1 atm). By adding calcium oxide solution into the carbon dioxide saturated solution, carbonated recycled aggregate was formed. To verify the physical properties of products, XRD analysis was performed and SEM images were obtained.
Studies on the Manufacture Properties of SPC (Sulfur Polymer Cement) Concrete using Coal Bottom Ash
( Bumui Hong ),( Chuljin Jeong ),( Changsik Choi ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2015 No.-
In this work, we constructed the sulfur polymer cement(SPC) concrete using coal bottom ash from 4 thermal power stations in korea and investigated their practical data for production of industrial construction compounds. To manufacture the SPC concrete, we used batch concrete mixer with the heating jacket using hot oil. Also, coal bottom ash was used as a fine aggregate below 2 mm. When the SPC concrete were produced with diverse sulfur concentration (15, 20, 25, 30 wt%), compressive strength properties were analyzed. We got the compressive strength of the maximum 60 MPa. These experimental results could be effectively applied to the recycling technology of coal bottom ash.
Design of Substructure for 3MW Offshore Wind Turbine Demonstrator Project
변철진(Byun, Chuljin),주완돈(Joo, Wandon),정석용(Jeong, Seokyong),박종포(Park, Jongpo) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11
The 3MW OWEC demonstrator project in Korea will be the first offshore wind project with Korean turbine, Doosan WinDS3000, and constructed on the north-eastern sea of Jeju Island as the water depth of 15m. Integrated loadings of wind and wave are investigated to describe a design loads for both extreme and fatigue conditions using GH-Bladed. A dynamic behaviour of substructure strongly affects a substructure loadings. The jacket structure is designed in accordance with DNV guidelines. The results of this paper show overall design process of offshore substructure as a complex jacket concept and this design process can be implemented on a design of monopile and tripod structures.