• Korean Chemical Engineering Research
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• 제61권4호
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• pp.598-603
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• 2023

촉매를 사용한 전기화학적 암모니아 생산은 주변 온도 및 압력 조건, 환경 친화적인 작동 및 고순도 암모니아 생산을 가능하게 함으로써 전통적인 하버-보쉬 방법을 대체할 대안으로서 가능성이 있다. 본 연구에서는 제1원리 계산을 사용하여 루테늄 촉매의 표면에서 발생하는 질소 환원 반응에 초점을 맞춘다. 루테늄의 (0001) 및 (1000) 표면에서 질소 환원에 대한 반응 경로를 모델링하여 반응 구조를 최적화하고 각 단계에 대한 유리한 경로를 예측했다. 각 표면에서의 N₂의 흡착 구성은 후속 반응 활동에 상당한 영향을 미쳤으며, 깁스자유에너지 분석은 가장 유리한 질소 환원 구성을 도출하였다. 루테늄의 (0001) 표면에서는 질소 분자가 표면에 수직으로 흡착하는 end-on 형태가 가장 유리한 N₂ 흡착에너지가 나타났으며 유사하게, (1000) 표면에서도 end-on 형태가 안정적인 흡착 에너지 값을 보였다. 이어서, distal 및 alternating 구성 모두에서 최적화된 수소 흡착을 통해 NH₃의 최종 탈착까지 이론적으로 완전한 반응 경로를 설명했다.

• 대한소아치과학회지
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• 제8권1호
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• pp.55-63
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• 1981

The purpose of this study is to observe the effect of formocresol and glutaraldehyde to tooth germs and periapical tissues after perforation of interradicular portion of pulpal floor and application of physiological saline solution in control groups, formocresol and glutaraldehyde in experimental groups. The following results were obtained 1. In control groups, normal healing processes were seen, and, on the sixteenth day, the epithelization of injured areas was completed. Inflammatory reactions were limited to the injured surface, and the underlying alveolar bone were normal and successive tooth germs were normal. 2. In both formocresol groups and glutaraldehyde groups, tissue reactions were identical. Inflammatory reactions were slightly compared with control groups, but the surface epithelizations were delayed compared with control group. 3. In both formocresol and glutaraldehyde groups, necrosis was seen in superficial tissue of bone marrow, and, at 24th day, center area of bone marrow on the successive tooth germs were losed and replaced with connective tissue, and superficial soft tissue of the injured area was connected with soft tissue on the successive tooth germ. In remaining alveolar bone, osteoclastic reaction was remarkable. 4. In both formocresol and glutaraldehyde groups, there is no injury to the successive tooth germs. 5. In both formocresol and glutaraldehyde groups, periodontal membrane was normal, but the partial resorption of cementum and dentin near the injured area were seen.

• Journal of Korean Society for Atmospheric Environment
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• 제21권E3호
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• pp.75-85
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• 2005

A mathematical sensitivity analysis of the flow-through dynamic flux chamber technique, which has been utilized usually for various trace gas flux measurement from soil and water surface, was performed in an effort to provide physical and mathematical understandings of parameters essential for the NO flux calculation. The mass balance equation including chemical reactions was analytically solved for the soil NO flux under the steady state condition. The equilibrium concentration inside the chamber, $C_{eq}$, was found to be determined mainly by the balance between the soil flux and dilution of the gas concentration inside the chamber by introducing the ambient air. Surface deposition NO occurs inside the chamber when the $C_{eq}$ is greater than the ambient NO concentration ($C_{0}$) introducing to the chamber; NO emission from the soil occurs when the $C_{eq}$ is less than the ambient NO concentration. A sensitivity analysis of the significance of the chemical reactions of NO with the reactive species (i.e. $HO_{2},/CH_{3}O_{2},/O_{3}$) on the NO flux from soils was performed. The result of the analysis suggests that the NO flux calculated in the absence of chemical reactions and wall loss could be in error ranges from 40 to $85\%$ to the total flux.

• 한국어병학회지
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• 제1권2호
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• pp.95-101
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• 1988

During the period from August through October, 1988, 50 isolates of Edwardsiella tarda were isolated from 6 diseased cultured Channa argus in Dunchi island and Myung-ghi, near Pusan in Korea were examined by studying their biochemical and antibiotical reactions. The ill animals moved slowly and irregular-formed swimming at the surface of the corner. The symthoms were necrosis with hemorrhage on the body surface, head, gill region, and mouth. Some fish were observed dropsy of the belly. The bacteria grew slowly on Double Salmonella-Shigella agar, 24h, at $37^{\circ}C$ to form relatively small size (2mm diameter), smoothed and convexed form with transient or black in center of the colonis. They gave negative reactions to Voges-Proskauer, Simmon's citrate, urea, KCN (in growth), gelatin, arginine dehydrolase, phenylalanine deaminase and many sugars. The isolates showed positive reactions to $H_2S$ (in KIA agar), indol, Methyl-Red, motility, lysine and ornithine decarboxylase, and gas from glucose. 8 drugs tested as chloramphenicol, colistin, gentamicin, kanamycin, lincomycin, nalidixic acid spectinomycin, and tetracycline. All cultures were resistant to colistin, lincomycin and spectinomycin respectibly, but sensitive to kanamycin and nalidixic acid. Three strains showed resistance to chloramphenicol and 2 isolates among them were resistant to two drugs(gentamicin and tetracycline), coincidentally.

• 한국표면공학회지
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• 제57권4호
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• pp.325-330
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• 2024

When seawater is used in electrochemical devices, issues arise such as the adsorption of chloride ions blocking the active sites for Oxygen reduction reactions (ORR) in seawater batteries, and the occurrence of Chlorine evolution reactions (ClER) in seawater electrolysis due to chloride anions (Cl^-) competing with OH^- for catalytic active sites, potentially slowing down Oxygen evolution reactions (OER). Consequently, the performance of components used in seawater battery and seawater electrolysis may deteriorate. Therefore, conventional alloys are often used by coating or plating methods to minimize corrosion, albeit at the cost of reducing electrical conductivity. This study thus designed a corrosion-resistant layer by doping carbon with Nitrogen (N) and Sulfur (S) to maintain electrical conductivity while preventing corrosion. Optimal N,S doping ratios were developed, with corrosion experiments confirming that N,S (10:90) carbon exhibited the best corrosion resistance performance.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.263-263
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• 2013

This work examines the dynamic properties of ice surfaces in vacuum for the temperature range of 140~180 K, which extends over the onset temperatures for ice sublimation and the phase transition from amorphous to crystallization ice. In particular, the study focuses on the transport processes of excess protons and chloride ions in ice and their segregative behavior to the ice surface. These phenomena were studied by conducting experiments with a relatively thick (~100 BL) ice film constructed with a bottom $H_2O$ layer and an upper $D_2O$ layer, with excess hydronium and chloride ions trapped at the $H_2O$/$D_2O$ interface as they were generated by the ionization of hydrogen chloride. The migration of protons, chloride ions, and water molecules to the ice film surface and their H/D exchange reactions were measured as a function of temperature using the methods of low energy sputtering (LES) and Cs+ reactive ion scattering (RIS). Temperature programmed desorption (TPD) experiments monitored the desorption of water and hydrogen chloride from the surface. Our observations indicated that both hydronium and chloride ions migrated from the interfacial layer to segregate to the surface at high temperature. Hydrogen chloride gas desorbs via recombination reaction of hydronium and chloride ions floating on the surface. Surface segregation of these species is driven by thermodynamic potential gradient present near the ice surface, whereas in the bulk, their transport is facilitated by thermal diffusion process. The finding suggests that chlorine activation reactions of hydrogen chloride for polar stratospheric ice particles occur at the surface of ice within a depth of at most a few molecular layers, rather than in the bulk phase.

• 센서학회지
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• 제7권4호
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• pp.263-270
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• 1998

본 연구에서는 특정한 생물학적 의미를 갖는 물질들간의 결합 및 분리과정을 실시간에 측정하기 위해 빠른 응답특성과 높은 감도를 갖는 표면 플라즈몬 공명 (Surface Plasmon Resonance, SPR) 현상을 이용한 센서 시스템을 제작하였다. SPR 시스템의 프리즘 표면에 일정 두께의 금 박막이 진공증착된 센서칩을 두고 이 아래에 위치한 시료충전셀에 살모넬라 (salmonella) 항체를 주입시켜 항체가 센서칩 표면에서 자기집합 (self-assembly) 함에 따라 공명각이 변화하는 현상을 측정하였다. 이후 분석대상물질인 살모넬라 항원을 주입하여 항체와의 결합 상태를 일정 시간 간격을 두고 공명각의 변화로서 측정하고 이 결과를 분석하였다. 또한 human Immunglobulin G (hIgG)를 항원으로 한 항원-항체 반응 역시 살모넬라의 경우와 같은 방법으로 측정하였다. 그 결과 살모넬라의 항체는 센서칩 표면에서 약 10분 동안 자기집합하고 반응이 포화됨을 공명각의 변화를 통해 볼 수 있었으며, hIgG의 항체의 경우는 약 60분 동안 반응을 하고 포화됨을, 그리고 살모넬라와 hIgG의 항원 (분석대상물질) 은 모두 각각의 항체에 대해서 약 1분 이내에 결합하고 포화됨을 볼 수 있었다.

• 전기화학회지
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• 제13권1호
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• pp.19-33
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• 2010

초기 충전 과정에서 흑연 음극에 생성되는 표면피막은 리튬 이차전지의 중요한 구성 요소로 전지 반응은 표면피막의 본질에 크게 영향을 받는다. 따라서 표면피막의 물리화학적 성질을 이해하는 것은 매우 중요하다. 한편, 표면피막의 형성 반응은 흑연/전해질 계면에서 진행하는 매우 복잡한 계면 현상이며, 표면피막은 반응성이 높고 공기 중에서 불안정하기 때문에 리튬 이차전지의 전극 표면을 연구하는데 있어서 in-situ 실험 기술은 매우 중요하다. 이와 같은 점에서 전위가 제어된 상태에서 다양한 전기화학 반응이 진행하는 전극/용액 계면을 직접 관찰할 수 있는 전기화학적 원자간력 현미경(Electrochemical Atomic Force Microscopy, ECAFM)은 매우 유용한 도구이다. 본 총설에서는 흑연 음극에 생성되는 표면피막의 본질적 이해에 중점을 두어 표면피막의 생성기구 및 전해질과의 상관성에 관하여 in-situ ECAFM 분석 결과를 중심으로 하여 정리하였다.

• Bulletin of the Korean Chemical Society
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• 제26권12호
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• pp.1953-1961
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• 2005

We have performed high-level quantum mechanical calculation for multiple proton transfer in HOCl + HCl and $H_2O$ + $ClONO_2$ on water clusters, which can be used as a model of the reactions on ice surface in stratospheric clouds. Multiple proton transfer on ice surface plays crucial role in these reactions. The structures of the clusters with 0-3 water molecules and the transition state structures for the multiple proton transfer have been calculated. The energies and barrier heights of the proton transfer were calculated at various levels of theory including multi-coefficient correlated quantum mechanical methods (MCCM) that have recently been developed. The transition state structures and the predicted reaction mechanism depend very much on the level of theory. In particular, the HF level can not correctly predict the TS structure and barrier heights, so the electron correlation should be considered appropriately.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 춘계 기술심포지움 논문집
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• pp.255-258
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• 2002

In this study, $CeO_2$thin films were etched with an addition of $Cl_2$gas to $Ar/CF_4$gas mixing in an inductively coupled plasma(ICP) etcher. The surface reactions of the etched $_CeO2$thin films were investigated by X-ray photoelectron spectroscopy(XPS). It was analyzed that Ce peaks were mainly observed in Ce-O bonds formed $CeO_2$or $CeO_3$compounds. Cl peaks were detected by the peaks of Cl $2p_{3/2}$ and Cl $2p_{1/2}$. Almost all of Cl atoms were combined with Ce atoms like $CeCl_{x}$ compounds.