• 한국안전학회지
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• 제33권5호
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• pp.28-34
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• 2018

Recently, various engineering approaches have been widely used in the accident investigation field to identify the cause of the accident and to predict damage by accident. Computational analysis is the most commonly used method of accident investigation technique. This technique is mainly used to identify the mechanism of the accident generation and to determine the cause when it is difficult to reproduce the situation at the time of the accident or when it is impossible to perform a reproduction experiment. In this study, The computational fluid dynamics analysis for nitrogen asphyxiation accident generated by defect of building structural between diffusion outlet and cooling tower was performed to determine the inflow path of the suffocation gas, death possibility by concentration of suffocation gas and predicted the time of death due to the accident using 3D modeling and FLACS program. We can quantify diffusion concentration of asphyxiation gas and predict mechanism of death occurrence by accident and evaluate the consequence Analysis through this study. In the future, This method can be widely used in the field of gas safety by improving the reliability and validity of the analysis.

• 한국정밀공학회지
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• 제26권1호
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• pp.97-104
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• 2009

There is a many kinds with nondestructive testing such as RT and UT representatively. Referred before two testing methods there is a limit which is spatial such as nuclear pipe, small vessel, sealing up vessel. So a new technique needs to overcome the limit which is spatial. shearography will be able to overcome the limit which is spatial. This paper introducing shearography which was known as non-contact full-field testing method and It is an interferometric technique for measurement of surface deformation such as displacement or displacement gradient. Also, a research about internal defect of the flange welding zone was accomplished. About variation with method pressurized with the Gaseous Nitrogen. Phase map where is various were measured according to changing a sheared direction, size of crack and loaded pressure. Consequently, crack quantitatively to be detected qualitatively was measured by using shearography.

• 대한유전성대사질환학회지
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• 제5권1호
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• pp.76-87
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• 2005

Various disorders cause hyperammonemia during childhood. Amongthem are those caused by inherited defects in urea synthesis and related metabolic pathways. These disorders can be grouped into two types: disorders of the enzymes that comprise the urea cycle, and disorders of the transporters or metabolites of theamino acids related to the urea cycle. Principal clinical features of these disorders are caused by elevated levels of blood ammonium. Additional disease-specific symptoms are related to the particular metabolic defect. These specific clinical manifestations are often due to an excess or lack of specific amino acids. Treatment of urea cycle disorders and related metabolic diseases consists of nutritional restriction of proteins, administration of specific amino acids, and use of alternative pathways for discarding excess nitrogen. Although combinations of these treatments are extensively employed, the prognosis of severe cases remains unsatisfactory. Liver transplantation is one alternative for which a better prognosis is reported.

• 한국표면공학회지
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• 제53권4호
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• pp.169-181
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• 2020

The ferroelectricity in emerging fluorite-structure oxides such as HfO₂ and ZrO₂ has attracted increasing interest since 2011. Different from conventional ferroelectrics, the fluorite-structure ferroelectrics could be reliably scaled down below 10 nm thickness with established atomic layer deposition technique. However, defects such as carbon, hydrogen, and nitrogen atoms in fluorite-structure ferroelectrics are reported to strongly affect the nanoscale polymorphism and resulting ferroelectricity. The characteristic nanoscale polymorphism and resulting ferroelectricity in fluorite-structure oxides have been reported to be influenced by defect concentration. Moreover, the conduction of charge carriers through fluorite-structure ferroelectrics is affected by impurities. In this review, the origin and effects of various kinds of defects are reviewed based on existing literature.

• Membrane and Water Treatment
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• 제6권3호
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• pp.251-262
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• 2015

In this work the preparation and characterization of a membrane containing a uniform mesoporous Titanium oxide top layer on a porous stainless steel substrate has been studied. The 316 L stainless steel substrate was prepared by powder metallurgy technique and modified by soaking-rolling and fast drying method. The mesoporous titania membrane was fabricated via the sol-gel method. Morphological studies were performed on both supported and unsupported membranes using scanning electron microscope (SEM) and field emission scanning microscope (FESEM). The membranes were also characterized using X-ray diffraction (XRD) and $N_2$-adsorption / desorption measurement (BET analyses). It was revealed that a defect-free anatase membrane with a thickness of $1.6{\mu}m$ and 4.3 nm average pore size can be produced. In order to evaluate the performance of the supported membrane, single-gas permeation experiments were carried out at room temperature with nitrogen gas. The permeability coefficient of the fabricated membrane was $4{\times}10^{-8}\;lit\;s^{-1}\;Pa^{-1}\;cm^{-1}$.

• 소성∙가공
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• 제21권1호
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• pp.36-41
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• 2012

Gas Assisted Injection Molding is a relatively new low-pressure injection molding technique that provides benefits such as reduced part warpage, excellent surface quality without shrink marks, greater design flexibility, etc. In the gas assisted injection molding process, the injected pressurized nitrogen gas flows through designed gas channels and forms hollow sections within the part. However, due to the characteristics of the gas, the design of the gas channels which are the paths for the injected gas is important in order to avoid defects such as gas blowout, fingering, etc. Therefore, in this study, the gas channel design for gas assisted injection molding of exterior display panels was conducted by examining the results of three CAE analyses. The designed gas channel was verified by conducting tryouts using a 450 ton injection molding machine with 3-stage pressure controlled gas kit. In addition, the hollow shapes which were formed by the gas with the installed gas channels were examined by examining the cross sections of the prototypes that were produced. As a result, it was found that exterior display panels can be produced without any defect by applying the gas assisted injection molding technique.

• 멤브레인
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• 제31권1호
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• pp.80-85
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• 2021

본 논문에서는 ~1.5 ㎛의 기공 크기를 가지는 고투과도 알파 알루미나 지지체 위에 도포된 서스펜션의 증발유도 자기조립 현상을 이용하여 중간층을 형성하는 새로운 코팅 방식을 소개한다. 새로운 코팅 방법으로 만들어진 중간층은 일반적으로 사용되는 담지법으로 코팅된 중간층과 비교하여 표면거칠기와 불균일도가 낮아 코팅에 적합하였다. 복합막 지지체로서의 평가를 위해 제조된 지지체는 감마 알루미나 복합막 제조에 사용되었다. 메조 기공을 가지는 감마 알루미나 복합막은 반복코팅 없이도 매크로 기공 크기의 결함이 존재하지 않았으며 일반적으로 널리 사용되는 100~200 nm의 기공 크기를 가지는 지지체로부터 만들어진 같은 두께의 복합막과 비교하여 2.3배 이상의 높은 질소투과도를 보였다.

• Clinical and Experimental Pediatrics
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• 제46권9호
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• pp.883-888
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• 2003

목 적 : 용혈성 빈혈은 진단방법의 발전과 관심의 증대로 해마다 빈도가 증가하고 있다. 저자들은 지난 15년간 용혈성 빈혈로 진단받은 환자들을 토대로 원인에 따라 적혈구 내적 요인과 외적 요인으로 나누어 임상적 양상을 후향적으로 조사하여 차이를 분석하였다. 방 법 : 1987년 1월에서 2002년 5월까지 연세대학교 의과대학 세브란스병원 소아과에 내원하여 용혈성 빈혈을 진단 받은 58명의 환자들을 대상으로 진단 당시 연령, 성별, 증상, 혈색소, 망상구 수, 백혈구 수, 혈소판 수, 총 빌리루빈과 간접 빌리루빈, 비장비대 여부, Coombs' 반응, Alanine aminotransferase/Aspartate aminotransferase, 혈액요소질소 및 크레아티닌 치, 소변 검사, 치료 방법, 재원일수, 수혈 횟수를 분석하였다. 결 과 : 전체 환자 58명 중 적혈구 내적 결함에 의한 용혈성 빈혈(group I)이 21례(36%)로 유전성 구상적혈구증 19례, glucose-6-PD 결핍증 2례가 있었고, 적혈구 외적 결함에 의한 용혈성 빈혈(group II)은 34례(59%)로 용혈성요독증후군 9례, 온항체에 의한 자가면역 7례, 한랭 항체에 의한 자가면역 6례, 약물에 의한 경우 4례, 신생아 용혈성 질환 3례, 기계적 손상에 의한 경우 2례, 전신성 홍반성 낭창 2례, 악성종양 1례였다. 미분류는 3례(5%)였다. 성별 분포는 남자 : 여자의 비율이 group I은 2.5 : 1(15명 : 6명), group II는 1 : 1.5(15명 : 22명)이었다. 두 군간의 임상 양상을 비교 분석하였을 때 통계적으로 의미 있게(P<0.05) 차이를 보인 항목으로는 진단 시 혈색소 치, 혈액요소 질소 및 크레아티닌 치, 비장비대 여부로 나타났다. 치료에 있어서 내적 요인에서는 비장절제술만 시행한 경우가 대부분이었으며 외적 요인에서는 스테로이드, 복막투석, 면역글로불린 등 다양한 치료가 시행되었다. 결 론 : 소아 용혈성 빈혈 환자에서 원인에 따른 임상 양상을 비교 분석하여 본 결과, 외적 요인으로 인한 경우 진단 당시 혈색소 치가 더 낮고, 혈액요소질소 및 크레아티닌 치가 더 높은 것이 의미 있게 관찰되었으며, 내적 요인으로 인한 경우 비장비대가 의미 있게 더 많은 것으로 나타났다.

• 한국광물학회지
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• 제21권4호
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• pp.435-442
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• 2008

천연, 합성, 그리고 처리된 보석용 다이아몬에 대한 NMR과 EPR 실험을 수행하였다. 동일한 실험조건에서 비교적 짧은 100 분의 실험시간 동안에 얻어진 $^{13}C$ NMR 스펙트럼을 통해 천연과 합성다이아몬드, 처리된 다이아몬드와 처리되지 않은 다이아몬드, 그리고 고온고압 처리된 다이아몬드와 전자빔 처리된 다이아몬드가 각각 서로 구별될 수 있는 가능성을 확인하였다. 보석용 합성 다이아몬드는 촉매제로 흔히 사용되는 전이금속의 상자기성 영향으로 $^{13}C$ NMR의 선폭이 1.6 ppm 이상으로 얻어졌고, 보석용 천연 다이아몬드는 처리방법에 무관하게 그 선폭이 0.5 ppm 이하로 얻어졌다. 고온고압 처리된 보석용 천연 다이아몬드의 선폭(0.5 ppm)은 전자빔 처리된 다이아몬드의 선폭(0.2 ppm) 보다 두 배 이상 넓은 것으로 나타났다. 처리된 보석용 천연 다이아몬드의 $^{13}C$ NMR 신호 세기는 처리되지 않은 보석용 천연 다이아몬드의 신호 세기에 비해 10배 이상 높게 얻어졌다. EPR 스펙트럼을 이용해 얻은 각 다이아몬드의 상자기성 결함(전자)의 농도와의 상관성을 검토해 본 결과, $^{13}C$ NMR 신호의 상대적 세기는 각 시료들에 함유되어 있는 상자기성 전파의 농도에 비례하여 증가하지만 전자빔 처리된 다이아몬드의 경우는 예외임이 밝혀졌다. 이를 통해 전자빔 처리된 다이아몬드의 경우 NMR 신호의 세기를 정하는 인자로 상자기성 불순물 성분 이외에 격자 성분도 고려해야 됨을 알 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.246-246
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• 2016

Tungsten-nitrogen (W-N) co-doping has been known to enhance the photocatalytic activity of anatase titania nanoparticles by utilizing visible light. The doping effects are, however, largely dependent on calcination or annealing conditions, and thus, the massive production of quality-controlled photocatalysts still remains a challenge. Using density functional theory (DFT) thermodynamics and time-dependent DFT (TDDFT) computations, we investigate the atomic structures of N doping and W-N co-doping in anatase titania, as well as the effect of the thermal processing conditions. We find that W and N dopants predominantly constitute two complex structures: an N interstitial site near a Ti vacancy in the triple charge state and the simultaneous substitutions of Ti by W and the nearest O by N. The latter case induces highly localized shallow in-gap levels near the conduction band minimum (CBM) and the valence band maximum (VBM), whereas the defect complex yielded deep levels (1.9 eV above the VBM). Electronic structures suggest that substitutions of Ti by W and the nearest O by N improves the photocatalytic activity of anatase by band gap narrowing, while defective structure degrades the activity by an in-gap state-assisted electron-hole recombination, which explains the experimentally observed deep level-related photon absorption. Through the real-time propagation of TDDFT (rtp-TDDFT), we demonstrate that the presence of defective structure attracts excited electrons from the conduction band to a localized in-gap state within a much shorter time than the flat band lifetime of titania. Based on these results, we suggest that calcination under N-rich and O-poor conditions is desirable to eliminate the deep-level states to improve photocatalysis.