• 공업화학
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• 제10권2호
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• pp.225-230
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• 1999

Li(DPM)을 원료로 hot wall 수평 관형 반응기를 이용하여 질소-산소 및 아르곤-산소의 분위기에서 $Li_2O$ 고체박막을 LPMOCVD법으로 합성하였다. XRD와 ESCA 분석으로부터 질소-산소 분위기에서는 $Li_2CO_3$막이, 아르곤-산소의 분위기에서는 $Li_2O$막이 성장하였음을 알아냈다. 성막된 산화리튬과 리튬카보네이트는 기판의 실리콘 성분과 반응하여 실리케이트를 형성하였다. 마이크로 trench법과 Monte Carlo 시뮬레이션에 의해 기상반응 속도상수 및 표면반응 속도상수가 얻어졌으며 이를 이용한 성막속도 계산치와 실험치를 비교한 결과 실험조건범위 내에서 잘 일치하였다.

• 자원환경지질
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• 제18권3호
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• pp.225-237
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• 1985

Mineralization of Daehwa and Donsan W-Mo deposits can be devided into three distinct depositional stages on the basis of mineral paragenesis and flnid inclusion studies; stage I, deposition of oxides and silicates ; stage II, deposition of base-metal sulfides and sulfosalts with carbonates; stage III, deposition of barren calcite and fluorite. Tungsten, molybdenum and tin mineralization occurred in stage I. Fluid inclusion studies reveal that ore fluid of stage I were homogeneous $H_2O-CO_2$ fluids containing 3.5~14.6 mol % $CO_2$. Minimum temperature and pressure of stage I ore fluids were $240^{\circ}C$ and 500 bars respectively. Salinities of aqueous type I inclusions in minerals of stage I range from 3.7 to 7.6 wt. % equi. NaCl. whereas those of $CO_2$-containing type III inclusions range from 0.3 to 4.4 wt. %. Temperatures of stage II ore fluids range from 200 to $305^{\circ}C$ on the whole and salinities were in the range of 3.2~7.2 wt. %. Homogenization temperatures of fluid inclusions in calcite and fluorite of stage III range from 114 to $186^{\circ}C$ and salinities were in the range of 0.9~4.3 wt. %. Sulfur fugacities during stage II deduced from mineral assemblages and tamperature data from fluid inclusions declined from earlier to later in the range of $10^{-11}{\sim}10^{-18}atm$. Fluid inclusion evidences suggest that the dominance of $CO_2$ in ore fluid during W-Mo mineralization is the characteristic features of Cretaceous W-Mo deposits of central district of Korea compared to those of Kyeongsang basin district.

• 한국표면공학회지
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• 제44권5호
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• pp.173-178
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• 2011

Separator of stack in polymer electrolyte membrane fuel cell (PEMFC) is high cost and heavy. If we make it low cost and lighter, it will have a great ripple. In this study, low carbon steel is used as base metal of separator because the cost of low carbon steel is very cheaper commercial metal material than stainless steels, which is widely used as separator. Low carbon steel has not a good corrosion resistance. In order to improve the corrosion resistance and electrolytic conductivity, low carbon steel needs to be surface treated. We made Chromium electroplated layer of $5{\mu}m$, $10{\mu}m$ thickness on the surface of low carbon steel and it was nitrided for 2 hours at $1000^{\circ}C$ in a furnace with 100 torr nitrogen gas pressure. Cross-sectional and surface microstructures of surface treated low carbon steel are investigated using SEM. And crystal structures are investigated by XRD. Interfacial contact resistance and corrosion tests were considered to simulate the internal operating conditions of PEMFC stack. The corrosion test was performed in 0.1 N $H_2SO_4$ + 2 ppm $F^-$ solution at $80^{\circ}C$. Throughout this research, we try to know that low carbon steel can be replaced stainless steel in separator of PEMFC.

• 한국지반환경공학회 논문집
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• 제7권6호
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• pp.23-34
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• 2006

본 연구에서는 보강재의 침하를 허용하는 침하형 보강토 옹벽의 거동을 평가하기 위하여 원심모형실험을 수행하였다. 실험결과는 연결부의 침하를 허용하지 않는 일반형 보강토옹벽에 대한 결과와 비교 분석하여 침하형 보강토 옹벽의 안정성을 평가하였다. 모형실험에서 전면판은 알루미늄판을 사용하였으며, 보강재는 알루미늄 호일을 이용하였으며, 뒤채움지반은 화강풍화토를 사용하였다. 실험결과, 침하자유형 보강토옹벽은 80g의 중력수준에서 완전한 파괴상태에 도달하였으며, 일반형 보강토 옹벽이 69g의 중력수준에서 파괴된 것을 감안하면 침하자유형 보강토 옹벽이 안정성이 우수하다는 것을 확인할 수 있었다. 또한, 69g에서 침하자유형 보강토옹벽 저면에서의 수직토압이 일반형에 비해 16% 정도 크게 측정되었다.

• 한국지반신소재학회논문집
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• 제11권2호
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• pp.21-30
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• 2012

본 논문에서는 2009년도 인천지역 토양오염 실태조사에 따른 오염 분포도를 분석하였다. 인천 남동국가 산업단지, 부평 이전 미군기지, 서구 매립지 등에서는 유류저장 시설, 자동차 및 유리 산업화, 군부대 시설에 따른 유류 및 중금속 유출 등의 산업 및 경제 활동으로 토양오염 분포도가 다소 높게 조사되었다. 특히 인천의 토양오염 우려 지역을 대상으로 수치해석을 통한 장래 오염 평가를 하였다. 향후 5년 후 불소와 석유계총탄화수소의 오염은 점차 정화 될 것으로 판단되지만, 오염지역의 관리가 소홀하거나 주변지역으로 유출시 이 기간 내에 주변 확산과 시간경과에 따른 오염 진행은 커질 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제30권7호
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• pp.930-937
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• 2017

Objective: The I pig is a long nurtured longstanding breed in Vietnam, and contains excellent indigenous genetic resources. However, after 1970s, I pig breeds have become a small population because of decreasing farming areas and increasing pressure from foreign breeds with a high growth rate. Thus, there is now the risk of the disappearance of the I pigs breed. The aim of this study was to focus on classifying and identifying the I pig genetic origin and supplying molecular makers for conservation activities. Methods: This study sequenced the complete mitochondrial genome and used the sequencing result to analyze the phylogenetic relationship of I pig with Asian and European domestic pigs and wild boars. The full sequence was annotated and predicted the secondary tRNA. Results: The total length of I pig mitochondrial genome (accession number KX094894) was 16,731 base pairs, comprised two rRNA (12S and 16S), 22 tRNA and 13 mRNA genes. The annotation structures were not different from other pig breeds. Some component indexes as AT content, GC, and AT skew were counted, in which AT content (60.09%) was smaller than other pigs. We built the phylogenetic trees from full sequence and D loop sequence using Bayesian method. The result showed that I pig, Banna mini, wild boar (WB) Vietnam and WB Hainan or WB Korea, WB Japan were a cluster. They were a group within the Asian clade distinct from Chinese pigs and other Asian breeds in both phylogenetic trees (0.0004 and 0.0057, respectively). Conclusion: These results were similar to previous phylogenic study in Vietnamese pig and showed the genetic distinctness of I pig with other Asian domestic pigs.

• 대한화학회지
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• 제33권5호
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• pp.522-529
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• 1989

팔라듐 촉매를 이용하여 할로겐화 비닐의 CO 첨가반응과 짝지음 반응을 동시에 진행시키는 CO 첨가 호모 짝지음 반응을 실시하여 비교적 좋은 수득률로 대칭 디비닐케톤 및 디비닐 ${\alpha}$-디케톤을 합성하였다. 촉매로는 palladium(II) acetate에 2mol%의 리간드를 사용하고 염기는 3당량의 tributylamine, 극성 용매를 사용하여 10기압의 일산화탄소 존재 하에 $100^{\circ}C$에서 반응을 실시한 경우 디비닐 ${\alpha}$-디케톤을 가장 좋은 수득률로 얻을 수 있었으며, 일산화탄소 상압 하에서는 주로 디비닐케톤이 합성되었다. 또한, 여러가지 할로겐화 비닐에 대해 위와 같은 반응조건으로 반응을 실시해 본 결과 예상한 대로 순조롭게 반응이 진행되어 여러가지의 디비닐케톤 및 디비닐 ${\alpha}$-디케톤을 선택적으로 합성할 수 있음을 확인하였다.

• 한국추진공학회지
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• 제10권3호
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• pp.18-25
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• 2006

체계 요구조건에 빠르고 정확한 자료제공을 위해 고체추진기관 구조체에 대한 설계자동화 프로그램인 'ProDes'를 개발하고 검증하여 그 성능을 입증하였다 주어진 체계설계 요구도 및 구속조건으로부터 총 개발기간과 인력을 획기적으로 감소시키며, 또 설계, 해석, 시뮬레이션 및 도면화 등 일련의 업무를 통합적으로 수행하기 위해 프로그램 개발이 수행되었다. 프로그램은 모듈화되어 있으며, 각 단계별 계산은 설계 변수별 적용연구가 수행되어 최종 설계 목표치에 도달되도록 구성 되어있다. 다양한 종류의 마스터 모델로 된 구성품과 체결형태는 구축된 라이브러리 DB 모듈로부터 얻어진다. 개발 프로그램을 이용한 추진기관 구조체 설계와 기존 상세된 설계를 비교 분석한 결과 서로 잘 일치함을 확인하였다.

• Journal of Welding and Joining
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• 제20권6호
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• pp.754-761
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• 2002

It has been reported that the creep characteristics on weldment which is composed of weld metal(W.M), fusion line(F.L), heat-affected zone(HAZ), and base meta(B.M) could be unpredictably changed in severe service conditions such as high temperature and high pressure. However, the studies done on creep damage in power plant components have been mostly conducted on B.M and not the creep properties of the localized microstructures in weldment have been thoroughly investigated yet. In this paper, it is investigated the creep characteristics for three microstructures like coarse-grain HAZ(CGHAZ), W.M, and B.M in X20CrMoV121 steel weldment by the small punch-creep-(SP-Creep) test using miniaturized specimen($10{\times}10{\times}0.5mm$). The W.M microstructure possesses the higher creep resistance and shows lower creep strain rate than the B.M and CGHAZ. In the lower creep load the highest creep strain rate is exhibited in CGHAZ, whereas in the higher creep load the B.M represents the high creep strain rate. The power law correlation for all microstructures exists between creep rate and creep load at $600^{\circ}C$. The values of creep load index (n) based on creep strain rate for B.M, CGHAZ, and W.M are 7.54, 4.23, and 5.06, respectively and CGHAZ which shows coarse grains owing to high welding heat has the lowest creep loade index. In all creep loads, the creep life for W.M shows the highest value.

• 한국임상수의학회지
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• 제25권5호
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• pp.385-390
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• 2008

The purpose of this study was to compare the long term prognosis of Ahmed valve implantation and medical therapy in dogs with early primary glaucoma. The medical records of dogs with early primary glaucoma from the Veterinary Medical Teaching Hospital of Seoul National University between January 2005 and May 2008 were reviewed. Five dogs underwent Ahmed valve implantation and medical therapy was performed in six dogs. Breeds of the dogs included Shih Tzu(n = 7), American cocker spaniel(n = 2), and miniature poodle(n = 2). Adequate intraocular pressure(IOP) was better maintained in the Ahmed valve implantation group than in the medical treatment group throughout the follow-up period. Mean time for vision loss to develop after treatment in the Ahmed valve implantation group($198.0{\pm}115.4$ days) was significantly longer than that in medical treatment group($43.2{\pm}30.4$ days, p < 0.05). Post-operative complications included occlusion of the tube by fibrin in the anterior chamber (n = 1), fibrous capsule about the episcleral base of the device(n = 1), and dislocation of the valve body(n = 1). It is considered that Ahmed valve implantation is more effective strategy to control IOP and maintain vision than medical treatment in early glaucomatous dogs.