• Bulletin of the Korean Chemical Society
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• 제25권4호
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• pp.533-538
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• 2004

Canonical sampling method has been presented to generate the initial conditions for reactive flux studies of organic reactions in water. Velocity Verlet version of Nose-Hoover chain dynamics algorithm has been employed to sample the initial conditions according to canonical distribution. The unstable normal mode of a transition state has been introduced to define a dividing plane separating reactant and product regions in reaction processes. This method has been implemented and tested for the case iels-Alder reaction of methyl vinyl ketone (MVK) and cyclopentadiene (CPD) in water, providing a reliable tool for further reactive flux molecular dynamics studies in condensed media.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.49-54
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• 2006

The present study conducted a numerical modeling on the diesel SCR (selective catalytic reduction) system using ammonia as a reductant over vanadium-based catalysts $(V_2O_5-WO_3/TiO_2)$. Transient modeling for ammonia adsorption/desorption on the catalyst surface was firstly carried out, and then the SCR reaction was modeled considering for it. In the current catalytic reaction model, we extended the pure chemical kinetic model based on laboratory-scale powdered-phase catalyst experiments to the chemico-physical one applicable to realistic commercial SCR reactors. To simulate multi-dimensional heat and mass transfer phenomena, the SCR reactor was modeled in two dimensional, axisymmetric domain using porous medium approach. Also, since diesel engines operate in transient mode, the present study employed an unsteady model. In addition, throughout simulations using the developed code, effects of space velocity on the DeNOx performance were investigated.

• Bulletin of the Korean Chemical Society
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• 제25권1호
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• pp.69-72
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• 2004

The N-alkylation of 4-aminopyrimidine with a tetrahydro-3-aza-cyclopropa[c]inden-5-one, which is a model reaction of the pharmacophore of duocarmycins, was studied with a quantum chemical method. We consider two factors for the acceleration of the N-alkylation; distortion and protonation of the model pharmacophores. The distortion of the spirocyclopropyl moiety in the model spirocyclopropylcyclohexadienone could induce an intrinsic energy of 3-4 kcal/mol, but the protonation on the carbonyl oxygen of the model cyclohexadienone lowers the transition energy of the N-alkylation of 4-aminopyrimidine dramatically (~46 kcal/mol) and is considered to play a major role in the enzyme reaction. The distorted and protonated spirocyclohexadienone is exothermally relieved to a phenol with the heat of reaction of -37 kcal/mol. The protonation process is proposed to be the mode of action of duocarmycins in the DNA alkylation.

• Bulletin of the Korean Chemical Society
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• 제1권1호
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• pp.30-35
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• 1980

The thermal decomposition reaction of ethyl bromide was studied in the temperature range of 724.5-$755.1^{\circ}K$. Pressure dependence of the reaction was observed in its fall-off region. A theoretical evaluation of the rate constants was carried out adopting RRKM formulation in the region and was compared with the experimental observation.The validity of theory was also reevaluated by using the observed results. The observed activation energy in this study and Arrhenius A-factor were 51.7 kcal/mole and $10^{12.5}$, respectively. The small A-factror in the study was discussed in terms of the formation of a tight activated complex and the molecular elimination as a prevalent reaction mode.

• Bulletin of the Korean Chemical Society
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• 제21권11호
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• pp.1095-1100
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• 2000

we have proposed a three-dimensional GLE approach to gas-surface reactive scattering, model H + H $${\rightarrow}$H_2/Si(100)-(2$ ${\times}$1) system, and the implementation of 3D GLE method on the hydrogen on silicon surface has been presented. The formalism and algori thm of the 3D GLE are worked properly in the reactive scattering system. The calculated normal mode frequencies of surface vibrations were almost identical to previous harmonic slab calculations. The reaction probabilities were calculated for two energies. The calculations show that a very large amount of energy is transferred in surface in low energy scattering. Three different types of reaction mechanisms has been observed, which can not be shown in flat and rigid surface models. Further work on the reaction mechanisms and calculations of the vibrational and rotation distributions of products is in progress. The results will be reported elsewhere soon.

• East Asian Economic Review
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• 제22권4호
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• pp.531-555
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• 2018

This article aims to review the monetary policy rule under inflation targeting framework focusing on Mongolia. The empirical analysis estimates the policy reaction function to see if the inflation targeting has been linked with a monetary policy rule emphasizing on inflation stabilization since its adoption in 2007. The study contributes to the literature by examining the linkage between Mongolian monetary policy rule and inflation targeting directly and thoroughly for the first time and also by taking into account a recent progress in the inflation targeting framework toward forward-looking mode. The main findings were: the Mongolian current monetary policy rule under inflation targeting is characterized as inflation-responsive rule with forward-looking manner (one quarter ahead); the inflation responsiveness is, however, weak enough to be pro-cyclical to inflation pressure; and the rule is also responsive to exchange rate due to the "fear of floating", which weakens the policy reaction to inflation and output gap.

• International Journal of Fluid Machinery and Systems
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• 제2권4호
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• pp.334-345
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• 2009

Pumped storage power plants are playing a significant role in the contribution to the stabilization of an electrical grid, above all by stable operation and fast reaction to sudden load respectively frequency changes. Optimized efficiency and smooth running characteristics both in pump and turbine operation, improved stability for synchronization in turbine mode, load control in pump mode operation and also short reaction times may be achieved using adjustable speed power units. Such variable speed power plants are applicable for high variations of head (e.g. important for low head pump-turbine projects). Due to the rapid development of power semiconductors and frequency converter technology, feasible solutions can be provided even for large hydro power units. Suitable control strategies as well as clear design criteria contribute significantly to the optimal usage of the pump turbine and motor-generators. The SIMSEN tool for dynamic simulations has been used for comparative investigations of different configurations regarding the power converter topology, types of semiconductors and types of motor-generators including the coupling to the hydraulic system. A brief overview of the advantages & disadvantages of the different solutions can also be found in this paper. Using this approach, a customized solution minimizing cost and exploiting the maximum usage of the pump-turbine unit can be developed in the planning stage of new and modernization pump storage projects.

• 미생물학회지
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• 제36권1호
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• pp.8-13
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• 2000

Trichoderma koningii ATCC 26113에서 분비되는 효소인 $\beta$-glucosidase를 cellobiose, sophorose, laminaribiose 및 gentiobiose 등의 기질과 반응시킨 후 효소의 transglycosylation 반응 산물을 분석하였다. 각각의 기질로부터 생성된 이당체(dimer)들을 HPLC로 분리하고 $^(1)H$-NMR spectroscopy를 통하여 분석하였다. Cellobiose를 기질로 사용하여 효소와 반응시켰을 때 그 산물에는 laminaribiose, sophorose 및 gentiobiose가 포함되었음을 확인할 수 있었다. Laminaribiose, sophorose 및 gentiobiose를 기질로 사용하였을 경우에 효소는 transglycosylation 반응을 통하여 새로운 $\beta$-glycosidic 결합을 갖는 이당체들을 생성하였다. 효소반응에 의하여 누적되는 이당체의 양은 생성속도보다는 분해속도에 의하여 결정되는 것으로 나타났다.

• 대한환경공학회지
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• 제27권10호
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• pp.1114-1122
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• 2005

이 연구는 초음파에 의한 1,4-dioxane(1,4-D)의 제거효율과 반응속도의 증가를 위해 초음파의 조사방식, 반응온도와 부피의 효과를 조사하였다. 초음파가 펄스방식으로 주사된 경우가 연속적으로 주사된 경우보다 약 10%의 1,4-D의 감소 효율의 증가를 보였다. 두 경우 모두 1000 mL와 반응온도가 고정되지 않은 조건에서 실시된 것으로 반응곡선은 도입단계, 가속단계, 그리고 안정화단계 등 3단계로 구분될 수 있었다. 실제로 1,4-D의 제거를 보이는 부분은 도입단계와 가속단계로 이들의 속도론적 특징은 도입단계와 가속 단계 각각 0차 반응과 유사일차반응과 부합하였다. 반면에 300 mL의 반응부피에서 온도를 고정한 경우에서는 3단계의 제거 유형을 보이지 않았다. $5^{\circ}C$로 고정한 경우만이 유사일차 반응과 부합하였고 그 이상의 온도에서는 0차 반응과 부합하였다. $20^{\circ}C$로 온도가 고정된 조건에서 반응부피 300 mL의 경우가 1000 mL 반응에서 보다 높은 분해 효율을 보였을 뿐만 아니라 단일한 제거 특성을 보였다. 이러한 반응 온도와 부피의 영향은 초음파 주사에 의해 생성되는 bubble의 강도에 영향을 주며 bubble의 강도가 높을수록 OH 라디칼의 생성이 증가되었다.

• 재활복지공학회논문지
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• 제11권1호
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• pp.81-89
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• 2017

본 논문은 대퇴절단 환자의 다양한 환경에서의 보행을 가능하게 하는 지능형 의족의 보행노면 및 보행단계 판별 기법을 제안한다. 제안하는 보행모드 변경 기법은 스트레인게이지 센서 만으로 보행노면 및 보행단계 판별이 가능한 단일 센서 기반의 알고리즘으로 기존 지능형 의족의 다중센서 기반 알고리즘의 단순화와 의족 시스템의 저가화가 가능하게 고안하였다. 보행노면 판별 알고리즘을 위해 정상인의 보행 중 발생하는 지면반발력의 특징을 분석하여 보행단계 세분화와 보행노면 검출 조건을 정의하였고, 대퇴절단 환자와 유사한 환경에서의 보행 실험을 위해 보행분석 장치를 제작하였다. 정의된 검출 조건과 제작된 기구를 통해 논문의 효용성 검증을 진행하였으며, 정상인 대상의 실험결과 단일 센서 기반 알고리즘의 정확도는 약 95%를 나타냈다. 제안하는 단일 센서 기반의 알고리즘을 통해 지능형 의족 시스템의 저가화가 가능할 것으로 판단되며 사용자가 직접 보행노면 상태를 파악하고 보행모드를 전환하는 수동 보행모드 변경 방식에서 벗어나 의족이 현재 보행 노면 상태를 파악하고 상황에 맞는 보행모드를 전환하는 자동보행 모드 변경이 가능할 것으로 확인되었다.