• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.111.1-111.1
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• 2011

The solar energy is dramatically increasing as the alternative energy source and the silicon(Si) solar cell are used the most. In this study, the improved process and equipment for the metallurgical refinement of multicrystalline Si were evaluated for the inexpensive solar cell. The planar plane and columnar dendrite aheadof the liquid-solid interface position caused the superior segregation of impurities from the Si. The solidification rate and thermal gradient determined the shape of dendrite in solidified Si matrix solidified by the directional solidification(DS) method. To simulate this equipment, the commercial software, PROCAST, was used to solve the solidification rate and thermal gradient. Si was vertically solidified by the DS system with Stober process and up-graded metallurgical grade or metallurgical grade Si was used as the feedstock. The inductively coupled plasma mass spectrometry (ICP) was used to measure the concentration of impurities in the refined Si ingot. According to the result of ICP and simulation, the high thermal gradient between the two phases wasable to increase the solidification rate under the identical level of refinement. Also, the separating heating zone equipped with the melting and solidification zone was effective to maintain the high thermal gradient during the solidification.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.97-97
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• 2012

비스코스 레이온 소재는 목재 펄프를 원료로 한 재생섬유로서 Drape성과 반발성은 탁월하나, 습식 방사에 따른 분자 구조적 불안정성으로 소비자가 일반 세탁 시 수축발생으로 종종 Dry Cleaning을 해야 하는 문제점들이 있음. 본 연구에서는 이와 같은 레이온의 단점을 극복하고 신축성 발현 및 형태안정성을 부여하기 위해 Rayon DTY사와 Spun T/R 40's를 개발하고 다양한 조직의 환편물을 제작하였으며, 기존의 레이온 제품 대비 수축률 등 형태안정성과 신축특성이 발현될 수 있는 염색가공 공정 조건을 설정하였음. 먼저 전처리시 균일하고 안정적인 수축이 발생하도록 하여 최종 생산품의 형태안정성과 신축성이 유지 될 수 있는 최적의 조건을 설정하였음. 전처리는 저온 축소 후 고온에서 정련하는 공정이 환편물의 조직에 관계없이 우수하였으며, 비교적 견뢰도가 우수하다고 판단되는 시판 분산염료 및 반응성염료를 사용하여 Polyester/Rayon의 2욕 2단 염색을 진행하였음. 또한 시제품의 품위를 높이기 위해 레이온 섬유의 고유한 특성을 부여할 수 있는 유연처방을 사용하여 총 13종의 환편물을 개발할 수 있었으며, 이렇게 개발된 원단은 형태안정성 -2.5~1.0%, 신장회복률 83% 이상, 필링성 4-5급의 결과를 나타내었음.

• Journal of Powder Materials
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• v.23 no.5
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• pp.372-378
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• 2016

This study focuses on the development of an alkaline leaching hydrometallurgy process for the recovery of tungsten from WC/Co hardmetal sludge, and an examination of the effect of the process parameters on tungsten recovery. The alkaline leaching hydrometallurgy process has four stages, i.e., oxidation of the sludge, leaching of tungsten by NaOH, refinement of the leaching solution, and precipitation of tungsten. The WC/Co hardmetal sludge oxide consists of $WO_3$ and $CoWO_4$. The leaching of tungsten is most affected by the leaching temperature, followed by the NaOH concentration and the leaching time. About 99% of tungsten in the WC/Co hardmetal sludge is leached at temperatures above $90^{\circ}C$ and a NaOH concentration above 15%. For refinement of the leaching solution, pH control of the solution using HCl is more effective than the addition of $Na_2S{\cdot}9H_2O$. The tungsten is precipitated as high-purity $H_2WO_4{\cdot}H_2O$ by pH control using HCl. With decreasing pH of the solution, the tungsten recovery rate increases and then decrease. About 93% of tungsten in the WC/Co hardmetal sludge is recovered by the alkaline leaching hydrometallurgy process.

• School Mathematics
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• v.13 no.2
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• pp.245-266
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• 2011

In this study, we surveyed on the 3rd and 4th grade teachers' perception and teaching practices towards open-ended question in the elementary mathematics textbook in the revised 7th curriculum. According to the result, teachers understood the purpose of open-ended question in general, but they recognized some problems in terms of open-ended question itself, difficulties found when they dealt with open-ended question in their classes, teacher's guide and teacher training. This research suggests ways of improvement of open-ended question on the basis of the survey results.

• Korean Architects
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• no.9 s.437
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• pp.93-101
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• 2005

지난 몇 년간의 연구와 출간된 글, 그리고 디자인 스튜디오 등 일련의 실험과정을 '하우징의 가변성 - 디자인의 연구 및 적용'이란 하나의 주제로 묶어 연재한다. 근본적으로, 이 연구 및 실험은 두가지 틀 속에 그 근간을 두고 있다. 첫째는 '이론과 실무'이고, 둘째는 '분석과 종합'이다. 건축 활동에 있어 이론과 실무는 불가분의 관계에 있다. 우리에게 흔히 '건축10서'라고 알려져 있고 현존 가장 오래된 건축 저서인 비트루비우스의 'De Architectura'의 첫번째 책, 첫 장 '건축가의 교육에 관하여'에서 비트루비우스는 건축가의 이론과 실무능력의 겸비를 강조하고 있다. 건축 디자인을 함에 있어 구체적이고 체계화된 이론과 그 이론의 디자인으로의 적용을 통한 상호 보완관계를 강조한다. 즉 디자인 작업이란 연구, 분석, 실험 행위로 구성되는 연속 과정을 하나의 전체로 종합시켜 이루어지는 결정체이다. 따라서 건축 디자인은 그 근본이 되는 이론적 지식의 습득과 연구 그리고 디자인으로의 실험적인 적용 및 응용을 통한 상호 보완관계 위에서 전개, 발전되어야 한다. 따라서 디자인 작업이 '이론과 실무'의 상호 보완적인 작업이라는 전제하에 연재를 이어간다. 접근 방식으로는 '분석과 종합'의 변증법적인 통합에 기초한다. 건축 디자인의 형태적 체계를 인식하거나 구성하기 위한 방법으로 분석과 종합은 서로 불가분의 관계를 가진다. 여기서의 분석은 논리적인 사고나 원리에 근거한 디자인을 비교 검증하는 과정으로 해석하고 디자인에 나타나는 어떤 공통 특징을 인식하는 것이고, 이에 의거해 정련하고 개괄하여 새로운 디자인을 만들어가는 것이 종합이다. 즉, 건축가의 작품의 분석적 작업을 통해 이론과 원리를 추출하고, 이 원리들을 다양한 새로운 디자인으로의 적용 가능성을 디자인 스튜디오 작업을 통해 그 가능성을 타진해 보는 방법을 말한다.

• Electrical & Electronic Materials
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• v.7 no.2
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• pp.130-137
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• 1994

Indium, element of group III, was refined by using zone refining for high purity refinement. We have found the impurities of T1, Zn, Fe, Cd, Pb, Ni, Cu, Sn in the refined indium with ICP-AES, so that 3.9 weight ppm of T1 was reduced to less than 1 ppm, 1.0 weight ppm of Zn was reduced to 0.7 ppm, 2.8 weight ppm of Cd was reduced to 2.5 ppm and 14.0 weight ppm of Sn was reduced to 6.7 ppm with 5 melten zone passes only. 3.9 weight ppm of T1 was reduced to less than 1 ppm, 1.0 weight ppm of Zn was reduced to 0.3 ppm, 2.8 weight ppm of Cd was reduced to less than 1.0 ppm and 14.0 weight ppm of Sn was reduced to 0.4 ppm after vacuum baking with 5 melten zone passes. The surface morpholgy of metal Indium thin film in each conditions showed that porosities were reduced in the front of sampled ingot after vacuum baking with 5 zone melten zone passes. The average electrical resistivity of Indium thin film was reduced from 1.4*10$^{-3}$ .ohm.-cm in Indium origin ingot to 7.9*10$^{-6}$ .ohm.-cm after zone refined with 5 melten zone passes.

• Journal of the Korean Society of Costume
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• v.57 no.1 s.110
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• pp.163-175
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• 2007

This study examines 74 pieces of textiles of Daegaya found in the Jeesan-dong Tomb and Saeng-cho Tomb, and analyzes their characteristics and weaving techniques. Dagaya is known to have produced ramie and hemp from bast fibers. The hemp textiles were all woven in plain weave, and the ramie textiles were woven either in plain weave or plain braid. The ramie textiles were slightly more dense compared to the hemp textiles, however, both had average densities between 0.92 to 0.93, showing that they are balanced plain weave textiles. It was also found that S twist threads were used in the production of the hemp and ramie textiles. The dyed textiles on iron remains were found to be the oldest textiles to use dying techniques for patterns. Silk textiles were woven in plain weave, twill weave, and leno weave. All of the silk were made with non-twisted thread. The densities were between 30 to 58.3 and the the density rates were 1.0 to 2.5 for plain weave silk, this showed that varieties of plain weaver created by different densities of warp and well. The average density of cho was $53.4{\times}22.5/cm^2$ the density rate was about 2.40, therefore warp was woven more dense compared to the weft. There were degummed and raw silk used in silk textiles, but most of them were found to be degummed thread.

• Textile Coloration and Finishing
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• v.12 no.1
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• pp.68-75
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• 2000

In this study, polyester DTY faille(yoryu) and N/NP microfiber fabrics were pretreated (desizing, scouring and shrinking) by Continuous Scouring and Shringking Equipment with rota-drum and conveyor type in which types were different with retaining method. The results were as follows. The shrinkage ratio of wp/wf direction of DTY fabrics scoured by conveyor type was 1.5/23% higher than those by rota-drum type at $97^\circ{C}$ with 10min. treatment. In this case, The shrinkage ratio of wp/wf direction by those types was about 15/27%, respectively. The shrinkage ratio of wp/wf direction of N/NP microfiber fabrics scoured by conveyor type was 1.5/23% higher than that by rota-drum type at $97^\circ{C}$ with 10min. treatment. The size add-on of DTY fabrics scoured at $97^\circ{C}$ with 10min. treatment by conveyor type and by rota-drum type were 0.15% and 0.42%, respectively. The size add-on of DTY fabric treated by rota-drum type decreased until 9min. of treated time, but increased after 9min. The size add-on of N/NP microfiber fabrics treated by conveyor type was decreased by increasing temperature and treated time, while the size add-on of that treated by rota-drum type was decreased until 6min. treated time and increased after 6min. The size add-on of N/NP microfiber fabrics treated by conveyor type at $97^\circ{C}$ for 10min. was 0.3% lower than that by rota-drum type.

• School Mathematics
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• v.12 no.3
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• pp.425-438
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• 2010

Wide employment of open questions is one of the notable features of Korean elementary school mathematics textbooks based on the national curriculum revised in 2007. This study closely looks into mathematics textbooks and teacher's guides for third and fourth graders in the revised curriculum, and discusses the ways those open questions are being presented and the assumed premises of the presentation. It then points out some problems associated with their contents and format, such as the problems with presentation contexts, question sentence styles, question sequences, and the like. Lastly, it summarizes the research issues for further study on open questions in terms of the meaning of open questions, guidelines for teachers, and the roles of teachers and textbooks.

• Journal of Korea Foundry Society
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• v.6 no.4
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• pp.284-289
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• 1986

Decarburization phenomena have been studied by plasma in stainless steel, plain carbon steel and cast iron. It was also investigated the movement of impurity element P,S in the plasma jet metal pool. The plasma jet was obtained by $Ar\;-\;CO_2$ gas mixture with 5 kVA DC power source. It produced enough temperature to dissociate into activated oxygen atom by reaction of $CO_2{\leftrightarrows}CO+O^+$ and it reacted with ${\underline{C}}$ in metal pool. Decarburization rate was increased about 5 times in comparing with the conventional induction melted metal pool by $CO_2$ gas decarburization. Even under the Ar plasma jet, decarburization was obtained by agitation of metal bath by $Ar^+$ bombardment and dilution phenomena of carbon atom under the very high plasma temperature. But heavy element P and S are not much removed because they are too heavy in mass to be activated by $Ar^+$ion bombardment. Desulphurization was achieved by $Ar\;-\;CO_2$ plasma in plain carbon steel and cast iron by the reaction of $SO_2({\underline{S}}+O^+)$. But dephosphorization could not be obtained by $Ar\;-\;CO_2$ plasma, because gaseous reaction of phosphorous oxide (${\underline{P}}+O^+$) was not existed.