• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.159-159
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• 2013

넓은 비표면적과 높은 전기전도성을 갖는 표면에 관능기가 도입된 RGO(reduced graphite oxide)를 modified Hummers method 와 thermal exfoliation 을 통해하여 합성하였으며 합성된 RGO를 PtSn alloy 촉매의 담지체로 도입하여 impregnation method를 통해 PtSn/RGO 시리즈 촉매를 합성하였다. XRD, SEM, TEM, XPS 분석을 통해 촉매의 특성을 분석하였고 methanol electrooxidation 활성을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3181-3182
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• 2013

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2001년도 가을 학술발표회 논문집
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• pp.452-455
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• 2001

고분자/실리케이트 나노복합체란 고분자 매트릭스에 층상 구조의 점토 광물을 나노 스케일의 시트상의 기본 단위로 박리(exfoliation)ㆍ분산시켜 얻어진 복합체를 말한다. 실리케이트를 구성하는 두께 1nm 정도의 판으로 박리ㆍ분산시키기 때문에 5wt% 정도의 첨가량만으로도 고분자의 획기적인 물성 개선이 가능하다는 장점을 가지고 있다[1]. (중략)

• 한국표면공학회지
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• 제36권4호
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• pp.291-295
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• 2003

Many steam turbine components encounter solid particle erosion damage. It has been reported that particle erosion damage is caused by oxide scale exfoliation from boiler tubes. One of the most effective solutions to combat the erosion damage is the application of erosion resistant coatings on the turbine components. In this study, particle erosion resistance for various hard coatings such as nitride, Cr carbide and boride coatings was evaluated under the simulated erosion conditions of steam turbines. Based on the particle erosion tests, the boride coating was found to be more superior to others.

• Bulletin of the Korean Chemical Society
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• 제19권10호
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• pp.1113-1116
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• 1998

A new graphite intercalation compound (GIC), n-octylammonium tetrachlorofeffate(Ⅲ)-graphite, has been derived from well-known ferric chloride graphite intercalation compound. X-ray diffration study shows that the basal spacing of this new GIC is 20.8 Å. In order to investigate the local geometry around the iron atom in the graphite layers, X-ray absorption spectroscopy experiments were performed. The first discharge capacity of its exfoliated form is found to be 862 mAh/g, which is more than double the value of pristine graphite (384 mAh/g). Such a drastic increase implies that the exfoliated graphite is a promising electrode material.

• 대한본초학회지
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• 제26권2호
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• pp.11-15
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• 2011

Objectives : In the present study, the contents of cinnamic acid and cinnamaldehyde in three different parts of Cinnamomi Ramulus (CR) (the whole body, the bark part, and the wood part) was evaluated using UPLC (ultra performance liquid chromatography) in order to investigate a suitable cutting method. Methods : Analysis was performed on SMART LC with UV detector. Reference compounds were separated on Inertsil ODS-4 column ($2.1mm{\times}50mm$, $3{\mu}m$, GL Science, Japan) using isolation elution with water and acetonitrile each containing acetic acid at a flow rate of $500{\mu}L/min$. Additionally, samples of CR were purchased from pharmacy of medicinal herb. Results : The correlation coefficients of the cinnamic acid and cinnamaldehyde levels showed good linearity ($r^2{\geq}0.9999$) over the linear ranges. Furthermore, the bark part exhibited higher concentration levels of reference compounds than the wood part in all samples. In addition the bark exfoliation rates in oblique and perpendicular-long cut samples of CR were lower than the perpendicular-short cut samples. Conclusions : These results suggested that the optimal cutting method would be able to reduce the bark exfoliation. Therefore, the oblique or perpendicular-long cutting method is considered to be a better cutting type than the perpendicular-short cutting method.

• 대한소아치과학회지
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• 제26권2호
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• pp.232-239
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• 1999

유치의 탈락과 영구치의 맹출은 정상적이고 예측 가능한 생리적인 과정이다. 치아 발육의 정확한 예측은 어린이의 치료 계획의 수립에 있어서 중요하다. 어린이의 연령과 그에 해당하는 치아 발육의 정상치가 여러 연구자들에 의해 조사되었다. 그러나 다양한 요소에 의해 치아의 정상 발육이 영향받을 수 있고 치아의 맹출을 촉진하거나 지연시킬 수 있다. 특히 농양이 있던 유치의 조기 발거나 탈락은 영구 계승치의 맹출에 뚜렷한 영향을 미칠 수 있다. 유치의 농양은 영구치를 덮은 골을 흡수시키고 따라서 발육상태에 관계 없이 영구치는 맹출할 수 있다. 유구치가 일찍 탈락 또는 발거되고 영구 계승치의 맹출이 조기에 일어나면 치아의 편향과 회전, 맹출 순서의 변경, 이웃 치아의 매복, 중심선 변위 등의 다양한 중요한 사건이 발생할 수 있다. 이에 저자는 서울대학교 병원 소아치과에 내원한 환아들의 조기 맹출한 영구 계승치의 임상적, 방사선학적 특징과 그로 인한 영향을 알아보고, 그에 따른 적합한 처치와 추후 관찰 사항을 보고하고자 한다.

• 한국건축시공학회지
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• 제7권4호
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• pp.125-132
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• 2007

The use of Self-Leveling material is increasing recently. This paper assesses the quality of surface layer of concrete floor when Self-Leveling material is defective. The paper shows how to predict the defect of SL material before construction begins. The relationship between the quality of surface layer of concrete floor and the defect of SL material was determined and the quality of surface layer of concrete floor was then estimated. The relations between the quality of surface layer and the defect of SL material were determine considering surface strength, moisture, and consistency of surface layer. Absorbing amount was used as the indicator of consistency and the absorbing amount of test material was measured. Then the relations between the test material and surface strength were determined. Generally concrete floor with greater consistency has greater surface strength, however in this study, we hound that high impact concrete floor could have lower surface strength as the consistency gets bigger. The relations between the level of defect occurred in SL material and the quality of surface layer were examined and we clarified that the surface layer with lower consistency gets higher possibility to occur exfoliation in early stage, one or two weeks after constructing SL material. When the consistency is sufficient, the occurring situation of defect depends upon the moisture of surface layer. Little amount of moisture gets higher possibility not to occur the defect. As the amount increases, fissure generates and early exfoliation may occur. In addition, the level of fissure is highly related with the surface strength.

• 자원환경지질
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• 제46권5호
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• pp.445-453
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• 2013

의성 탑리리 오층석탑(국보 제77호)은 통일신라시대의 대표적인 석조문화재이다. 현재 이 석탑은 지속적인 풍화로 인해 전체적으로 흑색, 황색, 백색변색이 발생되어 있으며 백색변색이 발생한 부분에서 미세균열, 박리박락, 입상분해가 집중적으로 분포해 있다. 표면오염물에 대한 분석결과, 흑색변색은 망간산화물, 황색변색은 철산화물, 백색변색은 석고와 타라나카이트로 인해 발생한 것으로 확인하였다. 또한, 석탑에 발생한 물리적 훼손은 암석내부에서 석고의 결정화 작용으로 인해 발생한 것으로 판단된다. 따라서 의성 탑리리 오층석탑을 장기적으로 보존하기 위해서는 보존처리 매뉴얼에 따라 석고를 중심으로 표면오염물을 제거하고 P-XRF를 활용한 정기적인 모니터링이 요구된다.

• 한국재료학회지
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• 제14권9호
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• pp.676-681
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• 2004

In-situ observation in SBM on the microfracture behavior of coating layer was performed for GA steel sheets that have various Fe contents and thickness of coating layer. In case of cross sectional side of coating layer that was in a tensile stress state during bending, fine perpendicular crack pre-induced during galvannealing grew and propagated rapidly toward the coating surface with the increase of strain. And then it grew and propagated along the ${\Gamma}/Fe$ matrix interface, and combined with the nearest another perpendicular crack. Consequently, flaking occurred. The more Fe content and thickness of coating layer increased, the more average crack interval and flaking resistivity increased. Exfoliation was little observed at coating surface in a tensile stress state.