• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.291-296
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• 2018

Direct synthesis of methylchlorosilanes was developed by Rochow with addition of copper on the silicon surface as a catalyst and many research were followed. Most of research were focused on the increase of reaction activity through addition of promoters and concentrated on the increase of selectivity of DMDC. However, there are very few studies about the reaction mechanism. Although formation of DMDC was explained in literature, formation of other silanes were not mentioned at all. This reseach focused on the explanation about formation of all silanes obtained during direct reaction and TPD. Reaction paths were proposed by means of dissociative adsorption of methyl chloride and spillover of surface Cl and H. Surface silicon sites were considered as $=SlCl_2$ and $=Sl(CH_3)Cl$. The synthesis of all methylchlorosilanes were explained by the adsorption of methyl group on the silicon sites and by the surface diffusion of nearby Cl and H. The proposed reaction mechanism explains the formation of all silanes during the reaction and also during the TPD process.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1988.11a
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• pp.67-74
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• 1988

고온성질 및 내마모 성질이 우수한 것으로 알려져 있는 요업재료가 아직 그 사용 영역이 크게 확장되지 못하고 있는 이유는 마모문제 때문이다. 종래 엔진재료로써 사용될 수 있을 것으로 크게 기대되어 왔던 사실과는 달리 아직도 성공하지 못하고 있는 것이 좋은 예이다. 이와 같이 요업재료에서의 마모가 중요한 문제로 대두함에 따라 최근 마모를 이해하기 위한 연구들이 실험적으로 또 이론적으로 활발히 진행되어 왔다. 그러나 마모는 접촉표면 및 부표면(subsurface)에서의 탄성 및 소성변형 또 화학적 반응등이 통상 복합적으로 작용하여 나타나는 매우 복잡한 것이기 때문에 아직도 그 기구는 분명하지 않다. 따라서, 요업재료에서 마모가 어떻게 일어나는 지를 밝히는 것은 아직도 매우 중요하다. 본 연구의 목적은 요업재료에서 미끄럼시의 마모기구를 실험적으로 밝히는 것이다. 비교적 제 성질이 잘알려져 있는 $Al_2O_3$를 모델계로 택하여 마모시험을 행하였으며, 미끄럼 시간에 따른 마모양상의 변화 및 접촉표면과 부표면에서의 미세구조 변화를 관찰하여 마모기구를 규명하였다.

• Microbiology and Biotechnology Letters
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• v.2 no.2
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• pp.63-77
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• 1974

The optimal operation problem of enzyme reactor of double inhibitions are dealt with Maximum Principle and Steepest Ascent Method. The operation policy of the intial concentration and amount of substrate, reaction time and the method of cross feed of substrate are determined in a system of reactor of constant volume add with cross feed of substrate. The policy for the soluble enzyme and the immobilized enzyme are greatly different from each other, and the performance index, the profit per unit time, of the latter are nearly twice greater than that of the former.

• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.112-117
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• 2002

A comparative investigation of an experimental and a simulation of chemical kinetics for NOx removal from silent(dielectric-barrier) discharges is presented. Several types of dielectric-barrier discharges were implemented depending upon the configuration of electrodes. The simulation was based on an approximate mathematical model for plasma cleaning of waste gas. The influence of non-uniform distributions of species due to the production of primary active particles in the streamer channel was taken into account. A comparison of observed experimental to the calculated removal efficiency of NOx showed acceptable agreement.

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.1015-1020
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• 2003

The Corrosion behavior of the matrix of the $\rho$-alumina bonded alumina vibrated castable was, on the basis of Jabsen's theory, elucidated by use of the Kingery's reaction mechanism. Corrosion of the matrix during induction period was controlled by the molecular diffusion. The temperature dependence of activation process is well established by the Arrhenius plots. The difference of Ca concentration between slag and interface is 23.2%, which causes a driving force of the materials transfer. The extent of the corrosion of the matrix is more deeper than that of the sintered mullite, but the corrosion mechanism can be well employed as the reaction mechanism proposed by the Kingery. The life time of the castable may be well estimated by the corrosion mechanism of Kingery.

• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.178-180
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• 2000

제올라이트의 결정성장은 유도기와 결정성장기 안정화기의 3단계로 진행한다 이러한 제올라이트의 결정성장 기구를 이해하고 결정의 성장기를 계속적으로 연장함으로서 조대한 NaX 제올라이트 결정의 성장을 유도하였으며, 선형결정성장속도에 대하여 고찰하였다. NaX 제올라이트의 수열합성 과정 중 결정성장기에 일정하게 3일 간격으로 반응용액내의 액상을 분리하고 반응겔을 보충하여 제올라이트의 합성 반응이 안정화기로 진행하는 것을 억제하고 결정 성장기를 연장하여 30㎛ 이상의 NaX 제올라이트 결정을 얻었다.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.47.4-48
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• 2018

밀러-유리 실험은 1950년대 처음으로 초기 지구의 대기 방전 실험으로 아미노산을 합성한 실험이다. 생명의 기원에 대한 내용이 교과서나 책에 실릴 때마다 빠지지 않고 등장하는 실험으로, 학생들의 탐구 활동 연구주제로 실험을 설계하여 진행하였다. 실험실 설계부터 시작하여 실험 과정인 유리기구 세척, 진공 만들기, 기체주입과 방전실험을 소개한다. 실험 장치가 완성 된 후, 실험 시간 23시간 중 약 4시간 동안 방전하여 갈색 용액을 얻는데 성공하였다. 아민기와 반응하는 ninhydrin 반응에서 양성반응을 보여 아미노산 수용액임을 확인하였다.

• Clean Technology
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• v.25 no.1
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• pp.46-55
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• 2019

CdS and CdZnS/ZnO materials were prepared using precipitation method and used as photocatalysts for the photocatalytic degradation of rhodamine B (RhB) under visible light irradiation. The prepared photocatalysts were also characterized by XRD and UV-vis DRS. The results indicated that the photocatalysts with intended crystalline structures were successfully obtained and both the CdS and CdZnS/ZnO can absorb visible light as well as UV. The photocatalytic activities were examined with the addition of scavenger for various active chemical species and the difference of reaction mechanisms over the catalysts were discussed. The $CH_3OH$, KI and p-benzoquinone were used as scavengers for ${\cdot}OH$ radical, photogenerated positive hole and ${\cdot}O_2{^-}$ radical, respectively. The CdS and CdZnS/ZnO showed different photocatalytic degradation mechanisms of RhB. It can be postulated that ${\cdot}O_2{^-}$ radical is the main active species for the reaction over CdS photocatalyst, while the photogenerated positive hole for CdZnS/ZnO photocatalyst. As a result, the predominant reaction pathways over CdS and CdZnS/ZnO photocatalysts were found to be the dealkylation of chromophore skeleton and the cleavage of the conjugated chromophore structure, respectively. The above results may be mainly ascribed to the difference of band edge potential of conduction and valence bands in CdS, CdZnS and ZnO semiconductors and the redox potentials for formation of active chemical species.

• Korean Journal of Materials Research
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• v.7 no.11
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• pp.957-963
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• 1997

PVC 핏치를 산소분위기에서 안정화시킬 때 발생되는 화학반응 기구를 열중량 분석 및 FT-IR을 이용하여 규명하였다. PVC 핏치를 안정화시킬 \ulcorner 초기에 가속화현상이 이러나서 핏치내에 반응성이 강한 메칠기(-CH/ sub 3/)나 메칠렌기(-CH$_{2}$-)등이 산소와 반응하여 카보닐기(C=O)를 생성하면서 급격한 무게증가 현상이 발생하였다. 이때의 생성물들은 알데히드(aldehyde), 케톤(ketone), 알코올(alcohol)이며, 물 (H$_{2}$O)이 부산물로 발생된다. 이 가속화 현상에 의해 핏치내의 메칠기와 메칠렌기는 안정화 초기단계에서 대부분 산화되어 없어졌다. 안정화시간이 길어짐에 따라 생성된 알데히드나 일차 알코올의 산화가 발생하여 카르복실산(carboxylic acid)을 생성하고, 에테르 결합도 생성되었다. 이때에도 무게증가 현상이 발생하지만, 초기의 급격한 무게증가와는 달리 그 증가속도가 느리고, 시간이 경과함에 따라 증가속도는 더욱 느려졌다. 그리고, 안정화온도가 높고 안정화시간이 긴경우에는,카르복실산들의 탈수반응으로 인한 방향족 무수화물(aromatic anhydride)이 생성되었다. 29$0^{\circ}C$에서 24시간 안정화시킨 경우, 무게감소가 발생했는데, 이것은 카르복실산의 탈카르복실화(decarboxylation)반응에 의해 CO$_{2}$가 발생되었기 때문이다. 그리고, 안정화 온도가 높을수록 안정화에 무게증가의 최대값과 방향족 무수화물이 발생되는 무게증가 값이 작아지고, 안정화 초기단계에서 나타나는 가속화 현상의 구간도 짧아졌다.

• Resources Recycling
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• v.9 no.4
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• pp.3-15
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• 2000

Reduction of Electric Arc Furnace dust with carbon (graphite) was studied at the temperature range of $800^{\circ}C$ to $1100^{\circ}C$ in Ar gas atmosphere. The briquetted dust with graphite powder was heated in a vertical tube furnace for given reaction time and Quenched in Ar gas atmosphere. It was found that initially the reduction of Zn was chemically controlled and the activation energy was about 120 KJ/mole. Because the almost all of Pb was removed with Cl in the form of $PbCl_2$, it is considered that Pb is removed by chloride reduction. Cu was vaporized as a chloride up to 30% of its original content, but the remaining of Cu would be accumulated with the reduced iron. and also, Cd was removed completely within 15 min. at $1000^{\circ}C$.