• 한국전기전자재료학회논문지
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• 제13권9호
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• pp.791-795
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• 2000

Amorphous chalcogenide glasses have a wide variety of light-induced effects. In this study, we have investigated the diffraction efficiency of chalcogenide. As$_{40}$ Ge$_{10}$ Se$_{15}$ S$_{35}$ thin films by the various applied electric fields. The holographic grating in these thin films has been formed using a linearly polarized He-Ne laser light (633nm). The diffraction efficiency was investigated the two method of applied electric field in the perpendicular and parallel to the direction of inducing beam. We obtained that properties of diffraction efficiency in the two methods of applied electric field. The result is shown that the diffraction efficiency of parallel electric field is 285% increase, η=1.1$\times$10$^{-3}$ and the diffraction efficiency of perpendicular electric field is 80% decrease, η=9.83$\times$10$^{-5}$ . Also, we have investigated the anisotropy property on chalcogenide thin films by the electric field effects.

• 소성∙가공
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• 제8권3호
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• pp.301-301
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• 1999

Austenitic stainless steels such as AISI 316L have been used in equipment in which fluid flows at high speeds which can induce cavitation erosion on metallic surfaces due to the collapse of cavities, where the collapse is caused by the sudden change of local pressure within the liquid. Usually AISI 316L is susceptible to cavitation erosion. This research focuses on developing a better material to replace the AISI 316L used in equipment with high speed fluid flow, such as impellers. The effects of Rare Earth Metal (REM) additions on the cavitation erosion-corrosion resistance of duplex stainless steels were studied using metallographic examination, the potentiodynamic anodic polarization test, the tensile test, the X-ray diffraction test and the ultrasonic cavitation erosion test. The experimental alloys were found to have superior mechanical properties due to interstitial solid solution strengthening, by adding high nitrogen (0,4%), as well as by the refinement of phases and grains induced by fine REM oxides and oxy-sulfides. Corrosion resistance decreases in a gentle gradient as the REM content increases. However, REM containing alloys show superior corrosion resistance compared with that of other commercial alloys (SAF 2507, AISI 316L). Owing to their excellent mechanical properties and corrosion resistance, the alloys containing REM have high cavitation erosion-corrosion resistance.

• 자원환경지질
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• 제30권4호
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• pp.371-377
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• 1997

This paper presents the geophysical applications to the environmenml problem in an abandoned mine area. We would like to focus our attention on the mapping of the soil contamination and the detection of the buried mine tailings. For mapping the soil contamination. measurements of both in-situ magnetic susceptibility (k) and terrain conductivity were carried out. In-situ magnetic susceptibilities of the contaminated soil due to the acid mine drainage show higher values than those of the uncontaminated area. However. those data do not show the correlation with the degree of the soil contamination observed on the surface. The least-squares fitted formula obtained with the measured insitu magnetic susceptibilities is $k=4.8207{\times}W^{0.6332}$, where W is the $Fe^{+2}$ weight percentage. This weight gives most effect to magnetic susceptibility of the soil. Lateral variations of the soil contamination in the shallow subsurface can be detected by the electrical conductivity distributions from EM induction survey. TDIP (Time Domain Induced Polarization) and EM induction surveys were conducted to detect the buried mine tailings. From the results of TDIP, the spatial zone, which shows high chargeability-low resistivity, is interpreted as the buried mine tailings. Therefore, it is concluded that it is possible to discriminate the spatial zone from the uncontaminated ground.

• Journal of Periodontal and Implant Science
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• 제40권4호
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• pp.153-163
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• 2010

Periodontal disease, as a polymicrobial disease, is globally endemic as well as being a global epidemic. It is the leading cause for tooth loss in the adult population and has been positively related to life-threatening systemic diseases such as atherosclerosis and diabetes. As a result, it is clear that more sophisticated therapeutic modalities need to be developed, which may include vaccines. Up to now, however, no periodontal vaccine trial has been successful in satisfying all the requirements; to prevent the colonization of a multiple pathogenic biofilm in the subgingival area, to elicit a high level of effector molecules such as immunoglobulin sufficient to opsonize and phagocytose the invading organisms, to suppress the induced alveolar bone loss, or to stimulate helper T-cell polarization that exerts cytokine functions optimal for protection against bacteria and tissue destruction. This article reviews all the vaccine trials so as to construct a more sophisticated strategy which may be relevant in the future. As an innovative strategy to circumvent these barriers, vaccine trials to stimulate antigen-specific T-cells polarized toward helper T-cells with a regulatory phenotype (Tregs, $CD_{4+}$, $CD_{25+}$, $FoxP_{3+}$) have also been introduced. Targeting not only a single pathogen, but polymicrobial organisms, and targeting not only periodontal disease, but also periodontal disease-triggered systemic disease could be a feasible goal.

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3644-3649
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• 2011

Multinuclear solid-state nuclear magnetic resonance (NMR) experiments were performed to investigate the local structure changes of nanoporous silica during hydrothermal treatment and surface modification with 3-aminopropyltriethoxysilane (3-APTES). The nanoporous silica was prepared by sol-gel polymerization using inexpensive sodium silicate as a silica precursor. Using $^1H$ magic angle spinning (MAS) NMR spectra, the hydroxyl groups, which play an important role in surface reactions, were probed. Various silicon sites such as $Q^2$, $Q^3$, $Q^4$, $T^2$, and $T^3$ were identified with $^{29}Si$ cross polarization (CP) MAS NMR spectra and quantified with $^{29}Si$ MAS NMR spectra. The results indicated that about 25% of the silica surface was modified. $^1H$ and $^{29}Si$ NMR data proved that the hydrothermal treatment induced dehydration and dehyroxylation. The $^{13}C$ CP MAS and $^1H$ MAS NMR spectra of 3-APTES attached on the surface of nanoporous silica revealed that the amines of the 3-aminopropyl groups were in the chemical state of ${NH_3}^+$ rather than $NH_2$.

• 지구물리
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• 제2권3호
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• pp.225-233
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• 1999

암석의 비저항값은 암석 자체의 성질뿐만 아니라 유체의 종류, 온도, 물 포화율, 접촉상태, 유도분극, 측정기기 및 사용전원의 주파수 등, 여러 요인에 의하여 영향을 받는다. 이 연구는 암석의 비저항을 정확하고 정밀하게 측정하기 위한 기초 연구의 일환으로서, 비저항 실측자료를 비교 분석하는 과정을 통하여 비저항 측정에 영향을 주는 다양한 요소들을 추적하고, 아울러 비저항 측정에 있어서 최적의 환경 조건을 찾고자 하였다. 특히 온도, 물 포화율, 시료와 전극의 접촉상태, 측정 주파수의 영향 등이 종합적으로 분석되었으며, 전도성 접착제와 절연 테이핑 방법 그리고 시계열 비저항자료의 이용이 비저항 측정의 정확도와 정밀도 향상에 크게 기여할 수 있음을 보였다.

• 한국표면공학회지
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• 제36권1호
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• pp.74-78
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• 2003

The corrosion failure of electronic devices has been a major reliability concern lately. This failure is an ongoing concern because of miniaturization of integrated circuits (IC) and the increased use of polymers in electronic packaging. Recently, plasma-polymerized cyclohexane films were considered as a possible candidate for a interlayer dielectric for multilever metallization of ultra large scale integrated (ULSI) semiconductor devices. In this paper the protective ability of above films as a function of deposition temperature and RF power in an 3.5 wt.% NaCl solution were examined by polarization measurement. The film was characterized by FTIR spectroscopy and contact angle measurement. The protective efficiency of the film increased with increasing deposition temperature and RF power, which induced the higher degree of cross-linking and hydrophobicity of the films.

• 센서학회지
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• 제28권4호
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• pp.262-265
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• 2019

The effect of inter-band transition on surface plasmon resonance in gold thin film was investigated. We induced localized inter-band transition in the film by using incident light on its surface from a green laser (532 nm) source, and the surface plasmon resonance for inter-band transition was investigated at different wavelengths. It was determined that the reflectivity of blue light (450 nm) was significantly reduced in the region where the green laser was incident. We demonstrated that this decrease is mainly due to the coupling between the blue light and the surface plasmon resonance of excited electrons in higher energy states, based on experimental results for the incident and polarization angle-dependent reflectivity of the blue light.

• 멤브레인
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• 제31권4호
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• pp.282-292
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• 2021

본 연구에서는 Dead-end와 Crossflow 시스템을 사용하여 유기용매 나노여과(Organic Solvent Nanofiltration, OSN) 상용분리막의 성능을 분석하였다. 가교된 polyimide 소재 기반의 Duramem (DM) OSN 분리막의 성능을 ethanol, dimethylformamide (DMF), acetone, acetonitrile 용매에서의 성능을 분석하였다. 네 종류의 분획분자량 성능을 갖는 DM 분리막의 성능을 평가하였을 때 dead-end보다 Crossflow에서 조금 더 정확하고 신뢰성 높은 결과를 얻을 수 있었으며, 동일한 분리막이더라도 용매의 특성에 따라 투과도와 선택도 차이가 크게 난다는 것을 확인할 수 있었다. 이는 압밀화현상으로 인한 초기 안정화 기간의 차이 때문인 것으로 판단되며 분리막마다 안정화기간이 다르므로 신뢰성 높은 결과를 얻기 위해선 Crossflow 시스템을 활용하는 것이 더 적합한 것으로 보인다.

• 대한금속재료학회지
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• 제46권10호
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• pp.652-661
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• 2008

Reduction of NOx in emission gas, improvement of engine efficiency, and extension of warranty period has made demands for developing materials more corrosively resistant to the inner-muffler environments or predicting the lifetime of materials used in muffler more precisely. The corrosion inside muffler has been explained with condensate corrosion mainly though thermal oxidation experiences prior to condensate corrosion. Hence, the aim of this study is to describe how the thermal oxidation affects the corrosion of stainless steel exposed to the inner-muffler environments. Auger electron spectroscopy and electrochemical tests were employed to analyze oxide scale and to evaluate corrosion resistance, respectively. Thermal oxidation has different role of condensate corrosion depending on the temperature: inhibiting condensate corrosion below $380^{\circ}C$ and enhancing condensate corrosion above $380^{\circ}C$. The low temperature oxidation causes to form compact oxide layer functioning a barrier for penetrating condensate into a matrix. Although though thermal oxidation caused chromium-depleted layer between oxide layer and matrix, the enhancement of the condensate corrosion in high temperature oxidation resulted from corrosion-induced crevice formed by oxide scale rather than corrosion in chromium-depleted layer. It was proved by aids of anodic polarization tests and measurements of pitting corrosion potentials. By the study, the role of high temperature oxidation layer affecting the condensate corrosion of stainless steels used as muffler materials was well understood.