• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.451-456
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• 2006

The process for reducing the weight of the structure is chiefly performed by the machine processing. But, increasing the weight for strength of welding zone and geometrical defect are occurred in machine processing. In this study, chemical milling is applied to reduce the weight of the cylinder. Before chemical milling is applied to the cylinder, specimen testing is performed. After the specimen testing, NaOH 15% is selected to perform the chemical milling. After the chemical milling, the velocity of reagent is 0.0016 mm/min and the thickness of cylinder is about 2.4 mm after chemical milling.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.504-509
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• 2004

Chemical machining(CHM) is a special process which material removed by contact of strong etchant. The application as industrial process was started from aircraft industry after 2nd world war. Chemical milling, one of the CHM process, initially became commercial bussiness and it was called chem-mill. Even today, this process widely used to remove the material from aircraft wings and fuselage panel in aircraft industry. In this study, it is attempted to design the cylinder pattern which minimize the weight within the allowable stress using chemical milling.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.164-164
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• 2008

금속배선공정에서 높은 전도율과 재료의 값이 싸다는 이유로 최근 Cu를 사용하였으나, 디바이스의 구조적 특성을 유지하기 위해 높은 압력으로 인한 새로운 다공성 막(low-k)의 파괴와, 디싱과 에로젼 현상으로 인한 문제점이 발생하게 되었다. 이러한 문제점을 해결하고자, 본 논문에서는 Cu 표면에 Passivation layer를 형성 및 제거하는 개념으로 공정시 연마제를 사용하지 않으며, 낮은 압력조건에서 공정을 수행하기 위해, 전해질의 농도 변화에 따른 Liner sweep voltammetry 법을 사용하여 전압활성화에 의한 전기화학적 반응이 Cu전극에 어떤 영향을 미치는지 연구하였으며, 표면 조성을 알아보기 위하여 Energy Dispersive Spectroscopy (EDS) 분석을 하였고, Cu disk의 결정성과 배향성 관찰을 위해 X-Ray diffraction (XRD)로 금속 표면을 비교하여 실험 결과로 얻어진 데이터를 통하여 ECMP 공정에 적합한 전해액 선정과 농도를 선택하였다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.3
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• pp.52-57
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• 2004

Many kinds of gases, such as erosion gas, dilution gas, and toxic gas have been used in manufacturing process of LCD at semiconductor. In order to increase accumulation rate of manufacturing process, high degree of purity in these gases and minimized metalllic dust are required. All wetted stainless steel surface must be 316L electro-polished with $0254{\mu}m$ in average. Based on the AES analysis, Cr/Fe 11 and $Cr_2O_3$ thickness $25{\AA}$ are measured Molybdenum and silicon contaminants which is characteristic of stainless steel and oxygen were found on the surface.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.187.2-187.2
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• 2011

태양광산업의 value chain중 up-stream쪽인 고순도 실리콘산업은 셀, 모듈, 시스템 쪽에 비하여 영업 이익률이나 부가가치 측면에서 매우 높은 성장성을 현재 보여주고 있으며 최근 원자력산업의 안전성 문제가 대두됨으로 인하여 태양광수요가 전 세계적으로 증대되는 경향을 나타내어 태양광용 실리콘의 수요가 확대됨과 아울러 spot시장에서의 가격 또한 상승하고 있다. 이런 관점에서 잉곳 및 웨이퍼 가공 중에 발생하는 고순도 실리콘 폐기물의 재활용 이 다시 주목받고 있다. 태양전지 웨이퍼(wafer)용 소재는 6N급 이상의 결정질 실리콘 잉곳(ingot)이 주를 이루며, 고효율의 셀을 제조하기 위해서 단결정 실리콘 잉곳이 많이 사용된다. 실리콘 단결정을 육성하는 방법에는 Floating zone 법, Czochralski 법, Bridgeman 법, CVD 등 매우 다양하다. 이 중 Czochralski 법은 전체 생산량의 대부분을 차지하고 있는 방법으로, 용융액에서 결정을 인상하여 ingot을 제작하는 방법이다. 그러나 대량의 전기에너지를 소비하여 제작되는 고순도의 실리콘 단결정 잉곳은 후 가공공정에서 그 절반 이상이 분말(powder) 및 슬러지(sludge)로 폐기되므로, 자원의 재활용 및 환경오염 측면에서 주요과제가 되고 있다. Czochralski 법으로 제작된 ingot의 경우 그 표면이 매끄럽지 못하여, 웨이퍼 단위의 가공 시 형태가 진원이 될 수 있도록 표면을 미리 연마(grinding)하는데, 이때에도 미세 분말이 다량 발생하게 된다. 본 연구에서는 이러한 고순도 단결정 실리콘 ingot의 연마 가공공정에서 발생한 미세 분말을 용해하여 보았다. 진공 챔버(chamber) 내부에 유도가열 코일과 냉도가니로 구성된 장비를 통해 전자기유도가열을 이용하여 실리콘 분말 폐기물을 용해하고, 그 시편을 ICP-MS 및 비저항 측정을 통해 분말 의 특성을 조사하여 재활용 가능성을 검토해 보았다.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.536-541
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• 1998

The porous size alumina membrane was prepared by anodic oxidation with current method in an aqueous solution of oxalic acid. The aluminum metal plate was pretreated with thermal oxidation, chemical polishing and electropolishing before anodic oxidation. Membrane thickness and pore size distribution were investigated with several anodizing conditions; reaction temperature, cumulative charge, electrolyte concentration and current density. The porous alumina membrane obtained was $55{\sim}75{\mu}m$ thick with straight micropore of 45~100nm. Also, the porous alumina membrane has an uniform pore diameter and pore distribution. It was inorganic ultrafiltration membrane as a kind of the ceramic membrane.

• The Korean Journal of Pharmacology
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• v.22 no.2
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• pp.123-127
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• 1986

n-Butyrate (n-BT A) increased the rate and number of infectious units produced in the in vitro reactivation of latent herpes simplex virus. While the mechanism of action of n-BT A is obscure, a continuous presence of n-BT A is necessary for its inductive effect.

• Journal of dental hygiene science
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• v.11 no.5
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• pp.405-410
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• 2011

The aim of this study was to evaluate antibacterial effect of Cl coated titanium. To coat the Cl on the titanium, first, the titanium was modified by blasting treatment with hydroxyapatite and alumina powder. Anodization process was completed using electrolyte solution of 0.04 M ${\beta}$-glycerol phosphate disodium salt n-hydrate, 0.4 M calcium acetate n-hydrate and 1 M NaCl on the condition of 250 voltages for 3 min. Surface morphology and elements' observation were performed with scanning electron microscopy and energy dispersive spectroscopy and surface profiler was used to analyze the surface roughness. Antibacterial effect was evaluated by film adhesion method. The anodized titanium after blasting showed dimpled surface contained the Cl. Surface average roughness of these surfaces had significantly higher compared to polished titanium. Result of antibacterial test showed that anodized titanium after blasting had an enhanced antibacterial effect compared to the polished titanium. Therefore, these results suggested that titanium contained Cl by anodization after blasting had a rough surface as well as antibacterial effect.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.95-99
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• 2002

To investigate the manual procedure for custom fitting of ocular prosthesis and the cytotoxicity induced by extract solution of prosthetic eye, this study was performed. These procedures included the trial fitting of the wax model, impression molding, the an of iris color duplication, sclera mold made from the prosthetic wax model, scleral tints and vascular pattern, finishing and polishing. Inhibition of cell growth for extract solution was measured by MTT assay. Extract solution did not show the cytotoxicity. This study suggests that the manual procedure for custom fitting of ocular prosthesis is good for education of students.

• The korean journal of orthodontics
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• v.25 no.3 s.50
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• pp.341-353
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• 1995

Previous study had shown the diversities in the propriety for optimal bond strength on the concentration of the etchant. The aim of present study in vitro was to evaluate and compare the shear bond strength of orthodontic brackets to enamel and to measure the depth of etch on the phosphoric acid concentrations. A hundred and seventy six extracted bovine lower centrals were ground to yield flat surfaces and etched by the concentration $0%,\;5%,\;10%,\;20%,\;30%,\;40%,\;50%,\;60%,\;70%,\;80%\;and\;85\%$ of phosphoric acid respectively during 60 seconds. The shear bond strength of orthodontic brackets, the depth of etch and surface roughness of the enamel were measured, and scanning electron microscopic observations on the etched enamel surfaces were carried out. The data obtained from the very experiments were processed and statistically analyzed and evaluated. The gradual increase in the depth of etch to enamel as the accretion of the concentration of the phosphoric acid upto $40-50\%$ and decline henceforth were manifested. The surface roughness showed no correlation with the depth of etch, yet moderate correlation with the shear bond strength of brackets. Scanning electron microscopic investigation revealed that morphological patterns of the etched enamel surfaces for $5\%\;to\;40\%$ of concentrations were even and homogenous, and those for $50\%$ as well as $60\%$ exhibited the overetched and unhomogenous. The shear bond strengths kom $10\%\;to\;60\%$ of concentration showed no statistically significant differences. It was suggested that the shear bond strengths at $5\%\;and\;70\%$ were sufficient to tolerate the force levels of the ordinary orthodontic treatment notwithstanding to be significantly lower than those from $10\%\;to\;60\%$ phosphoric acid solution.