• Resources Recycling
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• v.26 no.1
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• pp.3-10
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• 2017

The special properties of silver are often indispensable in the manufacture of advanced materials. Therefore, it is of importance to develop a process to recover silver which is necessary for the production of advanced materials from diverse resources. In this manuscript, the developed processes for the leaching of silver from diverse resources are reviewed. For this purpose, the advantages and disadvantages of using some inorganic acids (nitric and sulfuric acid) and their mixture with other oxidizing agents (ozone, oxygen, hydrogen peroxide and ferric ion) were investigated. Moreover, the leaching of silver with thiourea and thiosulfate was compared over those by inorganic acids in terms of environmental effect.

• Resources Recycling
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• v.26 no.5
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• pp.3-11
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• 2017

Solvent extraction is an important process to recover pure gold and silver from various leaching solutions. The present work reviews the aqueous chemistry and solvent extraction separation of gold (I, III) and silver (I) from several leaching systems such as cyanide, thiocyanate, thiosulfate, thiourea and chloride medium. The extraction and separation behavior of gold (I, III) and silver (I) by various single and mixtures was compared on the basis of extraction reaction and the selectivity from these mediums. The chloride medium is recommended for the separation of gold and silver by solvent extraction in terms of extraction and stripping efficiency.

• 한국벤처창업학회:학술대회논문집
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• 2020.06a
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• pp.85-93
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• 2020

본 연구는 전국의 대학생들을 대상으로 창업의지의 선행 변수을 규명하기 위해 구조모형으로 실증분석 하였다. 선행연구를 바탕으로 창업가정신을 독립변수로, 창업동기와 창업효능감을 매개변수로, 창업의지를 종속변수로 설정하였다. 진취성이 높을수록 창업동기에 정(+)의 영향을 줄 것이라는 가설1은 기각되었다. 혁신성이 높을수록 창업동기에 정(+)의 영향을 줄 것이라는 가설 2는 채택되었다. 위험감수성이 높을수록 창업동기에 정(+)의 영향을 줄 것이라는 가설 3은 채택되었다. 진취성이 높을수록 창업효능감에 정(+)의 영향을 줄 것이라는 가설 4는 채택되었다. 혁신성이 높을수록 창업효능감에 정(+)의 영향을 줄 것이라는 가설 5는 채택되었다. 위험감수성이 높을수록 창업효능감에 정(+)의 영향을 줄 것이라는 가설 6은 기각되었다. 진취성이 높을수록 창업의지에 정(+)의 영향을 줄 것이라는 가설 7은 기각되었다. 혁신성이 높을수록 창업의지에 정(+)의 영향을 줄 것이라는 가설 8은 채택되었다. 위험감수성이 높을수록 창업의지에 정(+)의 영향을 줄 것이라는 가설 9는 기각되었다. 창업동기가 높을수록 창업의지에 정(+)의 영향을 가설 10은 채택되었다. 창업효능감이 높을수록 창업의지에 정(+)의 영향을 가설 11은 채택되었다. 본 연구의 시사점은 창업교육이나, 창업동아리활동, 창업경진대회 등의 활동경험이 없는 전국대학생을 대상으로 조사하였다는 점이 선행연구와의 차별점이다. 또한 대학생들의 창업가정신, 창업동기 및 창업효능감, 창업의지와의 구조관계를 실증 연구하였다는 것이 선행연구의 차별점이다. 실증연구 결과를 통해 창업의지를 높이기 위한 방안이 무엇인지를 규명하고 제시하였다.

• Journal of Conservation Science
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• v.30 no.1
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• pp.95-101
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• 2014

Silver objects tarnish with black from reaction with sulfurous acid or hydrogen sulfide of atmospheric. Blackening of silver objects results from formation of silver sulfide($Ag_2O$) on the surface. Silver sulfide usually is usually removed by conservation treatment. There are several cleaning methods such as chemical, electrochemical and micro-abrasion cleaning, but all of them consume silver. This study investigated the safe and effective parameter of laser cleaning by test on silver coupons. Laser cleaning is a selective process for the removal of specific substances. At first, laser cleaning applied to plain silver coupons, which were not corroded, to find out the safe range of laser energy density. From results, plain silver coupons were not changed at 1064nm below $4.00J/cm^2$ and at 532nm below $2.39J/cm^2$. The corrosion layer(silver sulfide) of artifical corroded silver coupons was removed at 1064nm with $2.39J/cm^2$ by 5~10 pulses and at 532nm with $1.19J/cm^2$ by 5~10 pulses. The removal thickness of corrosion layer was about 13-25nm per a laser pulse using AES analysis. In addition, laser cleaning tested the tarnish silver rings based on the results of silver coupons. As a result of test, the black surface were clean successfully and gave luster of silver, which showed the application possibility of laser cleaning for silver objects.

• Journal of the Korean Vacuum Society
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• v.21 no.4
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• pp.205-211
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• 2012

We investigated the optical and hydrophobic properties of the deposited silver (Ag) zinc oxide (ZnO) nanorods (NRs) on flexible indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates (i.e., ITO/PET). The ZnO NRs were grown by an electrochemical deposition using a sputtered ZnO seed layer and the Ag was deposited by using a thermal evaporator. For comparison, the same fabrication process was carried out on the bare ITO/PET without ZnO NRAs. Due to the discrete surface of ZnO NRs, the deposited Ag was formed as nano-scale particles, while the Ag became film-like for bare ITO/PET. In order to control the size and amount of Ag particles, the Ag deposition time was changed from 100 to 600 s. When the deposition time was increased, the Ag particles became larger and denser, and the absorptance was increased. This enhanced absorptance may be due to the localized surface plasmon resonance of Ag particles. Furthermore, the relatively high hydrophobicity was observed for the deposited Ag on the ZnO NRs/ITO/PET. These improved optical and surface properties are expected to be useful for flexible photovoltaic and optoelectronic devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.372-372
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• 2011

은 나노선은 높은 전자이동도, 유연성이 우수하며 전극으로 사용하였을 때 전자의 수집 및 전달에 용이하여, 태양전지, 디스플레이 소자 등에 적용하기 위해 연구되고 있다. 본 연구에서는 에탄올에 20% 희석된 은 나노선 농도를 조절하고 이를 스핀코팅하여 투명전극을 제작하였다. 제작된 투명전극의 투과율과 면 저항의 최적화를 통해 P3HT : PCBM의 흡수층을 이용한 유기태양전지를 제작하여 태양전지의 특성을 분석하였다.

• Digital Contents
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• no.5 s.132
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• pp.102-103
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• 2004

이름도 낮선 조그마한 애니메이션 제작자가 최근 업계의 주목을 받고 있다. 애니메이션 투텐스타인(한국명:타탕)의 제작자인 은아트가 그 주인공. 은아트가 최근 관심을 끌고 있는 것은 이회사가 제작한 첫번째 애니메이션 투텐스타인이 지난 3월 미국 에미싱 본선 후보작으로 선정된 것을 비롯해 지난달에는 유럽 방송 연맹이 주관하고 유네스코에서 후원하는 국제 청소년싱(2004 Prix Jeunesse International)에서도 본선 최종후보작으로 선정되는 등 인기를 끌고 있기 때문이다. 이제 막 서른 줄에 접어든 젊은 대표 서은아 사장이 이끌고 있는 은아트를 찾았다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.113-113
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• 2016

반도체 웨이퍼 패키지 공정에는 솔더 범프용으로 주석-은 합금 도금액이 사용되어 왔다. 최근, 주석-은 도금 피막중의 은 함량의 불균일성, 불용성 양극의 사용에 의한 전압 상승. 은의 도금 치구에의 석출, 리플로 후의 보이드의 형성 등의 문제로 인하여 주석 단독 금속 도금에 의한 범프 형성이 실용화되었다. 본 연구에서는, 범프용 주석 도금액에서의 전류밀도, 금속이온의 농도, 유리산의 농도 및 첨가제의 농도가 범프 두께 균일성에 미치는 영향을 조사하였다.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.341-343
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• 2007

본 연구개발에서는 은나노를 포함한 비오염성 석재용 실리콘 실란트를 제조하였다. 기본적인 실리콘 실란트 Formulation에 오일에 의한 오염성을 최소화하기 위해 편말단 폴리머를 사용하였다. 폴리머 가교를 통해 접착성과 작업성 등의 물성을 향상시켰으며, 나노크기의 은 powder를 사용하여 항균성을 부여하였다. 가장 큰 관건은 nano size의 은을 가장 균일하게 실란트에 분산시키는 것이 실란트 제품화의 주요 기술이었다.

• Korean Journal of Food Science and Technology
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• v.11 no.1
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• pp.1-7
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• 1979

This experiment was carried out to investigate the nutritive value of brewery's activated sludge on the performance and nutrients utilization of egg type chicken of babcock fed the different levels of sludge. The chemical composition, content of amino acids and mineral in brewery's activated sludge were also analyzed. 3,6,9 and 12% of brewery's activated sludge were supplemented with basal ration as a substituted ingredient to soybean oil meal in experimental ration. The results obtained were as follow: 1. Chemical composition analysis 1) Brewery's activated sludge had 42.50% of crude protein on the air dried basis, and had 15,69% of crude ash, and had 2,060 kcal of metabolizable energy per kg of sludge. 2) Total amino acid content of brewery's activated sludge was 42.50% and 99% crude protein of brewery's activated sludge was a true amino acid, and brewery's activated sludge contained especially more methionine and threonine that those of soybean oil meal. 3) In case of mineral content of brewery's activated sludge, phosphorus, magnesium, copper and iron were plentifully included. However, calcium content in brewery's activated sludge was very low. 2. Feeding trial 1) Body gain of chicken fed the different levels of sludge was decreased in proportion to increasing level of sludge was decreased in proportion to increasing level of sludge. However, no statistical differences were found out between treatments. 2) Diet intake of chicken fed the different levels of sludge was significantly (p<0.05) increased as the supplementation level of sludge in ration increased. 3) Feed conversion of chicken fed the different levels of sludge was high in proportion to increasing level of sludge in ration. However, there were no significant differences between treatments. 3. Digestion trial 1) Utilization of dry matter of chicken fed the different levels of sludge was decreased as the level of sludge in ration increased. However, no statistical differences were found out between treatments. 2) Utilization of crude protein of chicken fed the different levels of sludge was significantly (p<0.01) increased as the level of sludge was higher. Utilization of crude protein of control treatment and of sludge 3% treatment was higher than that of other treatments. 3) Utilization of crude ash of chicken fed the different levels of sludge was significantly (p<0.05) decreased in proportion to increasing level of sludge in ration. 4) Utilization of NFE of chicken fed the different levels of sludge was slightly decreased in proportion to increasing level of sludge in ration. However, no statistical differences were found out between treatments. Therefore according to this experiment, it may be concluded that brewery's activated sludge can be supplemented with chicken ration by $6{\sim}9%$.