• 대한화학회지
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• 제52권3호
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• pp.217-222
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• 2008

본 논문에서는 반응 매질의 부피가 촉매 반응 속도에 미치는 영향을 조사하였다. 단순하지만 정확한 모델에 대한 연구로부터 촉매 반응의 반응 속도 계수는 매질의 부피가 줄어들 수록 증가함을 알게 되었다. 평균 반응속도 상수(average reaction rate constant)는 Collins-Kimball 속도 상수의 일반화 된 형태로 얻어졌는데, 속도 상수는 부피의 효과를 보정해주는 인자를 포함하고 있다. 조사한 모델의 반응물 농도는 전통적 화학 반응론에서 예측되는 지수함수적 감소와는 상당한 차이를 보이는데 이는 기존 화학 반응속도론에서는 무시되는 반응분자 공간 분포의 비평형 확산운동(non-equilibrium diffusive dynamics)의 효과 때문이다. 반응 매질의 부피 가 유한한 점을 고려하면, 반응 시간이 충분히 오래 지났을 때, 기존의 확산지배 반응에서는 예측 되는 않는 지수 함수적 농도 감소가 얻어지는데, 그 속도 상수 역시 반응매질 크기에 의존한다.

• 한국세라믹학회지
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• 제45권8호
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• pp.439-442
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• 2008

A series of reaction-sintered SiC was fabricated from preforms with varying volume fractions of two resin-coated SiC particles of different sizes (63 and $18{\mu}m$). The electrical resistivity and mechanical strength were eventually optimized at the small particle volume fraction of $0.3{\sim}0.4$, at which point the porosity of the preform was minimized. This study experimentally proves that additional processes after the formation of the preform, such as silicon infiltration and reaction sintering, do not apparently alter the optimum volume fraction of the preform packing, predicted by an existing analytical model based on solid packing. Thus, the volume fraction of particles of different sizes can be determined practically through the solid packing model to fabricate RSSCs with optimal properties.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제21회 KOSCO SYMPOSIUM 논문집
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• pp.212-216
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• 2000

Combustion phenomenon in scale-downed combustor is investigated. As the combustor volume decreases surface to volume ratio increases. for increased surface to volume ratio means increased heat loss and this increased heat loss affects reaction in combustion chamber. Plastic mini combustor is made. Stoichiometricaly premixed Hydrogen I air gas is used as fuel. Initial chamber pressure and chamber size are varied and the effects are evaluated. Peak pressure decreases with the decrease in chamber height. As initial chamber pressure decreases peak pressure decreases. And this change is more important than scale down effect till the chamber height of 1mm. With this result and further information following the experiments design parameter for micro engine can be established.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2004년도 추계학술대회 논문집
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• pp.355-360
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• 2004

This study is a research that evaluates and analyzes on the subjective reaction of Won buddhism small sanctum through psychoacoustics experiment. For doing it, after choosing of 5 Won buddhism small sanctums of which its building volume at $400m^{3}{\sim}650m^{3}$, a psychoacoustics experiment has been conducted. Based on those A, B, C, E temple-halls which appeared as higher than 'average' in the result of subjective reaction evaluation of the Won buddhism small sanctum through psychoacoustics experiment, it could be classified as the conclusion of the factor analysis: the first factor is 'space sense of sound', the second factor is 'intimacy-feeling with sound' and the third factor is 'clearness of sound', respectively.

• 환경위생공학
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• 제14권1호
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• pp.54-61
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• 1999

The industrial techniques of ultrasound have been used in the various fields, such as cleaning, medical surgery, emulsification, cell disruption etc. Especially the application of cell disruption was interested in the field of disinfection process in water by ultrasonic irradiation. It has been recognized that the ultrasounds are irradiated in aqueous solution, cavitation bubbles are generated and shock waves of high temperature and pressure are emitted as the bubbles are developed and finally broken, which function as a energy source to promote reaction efficiencies of various kinds of chemical reactions such as disinfection reaction in water. Therefore, this study was performed to apply the ultrasound for the disinfection method of infected drinking raw water and to discuss the limiting factors such as pH, sample volume and reaction temperature influenced on the removal efficiency of E. coli from experimental analysis of the results obtained in bench-scale plant. For the experiments to measure the influence of reaction parameters in the ultrasonic disinfection process, escalated reactivity of aqueous solutions was excellent when pH in aqueous solution was low, and sample volume was small. On the contrary, the reactivity of disinfection became elevated when reaction temperature was high. It was found that the rate constant of disinfection reaction was applied by Chick's law, reaction kinetics of Chick's law was irreversible and pseudo-first order at all the tested conditions.As a conclusion it appeared that the technology using ultrasonic irradiation can be applied to the treatment of disinfection in infected water which are difficult to be treated by conventional methods.

• Journal of Microbiology and Biotechnology
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• 제12권1호
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• pp.149-152
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• 2002

The effect of pressure on the catalytic properties of glutamate racemase from Aquifex pyrophilus, an extremophilic bacterium, was investigated. The activation volume for the overall reaction $({\Delta}V^{\neq})$ and catalysis $({{Delta}V_{cat}}^{\neq})$ was -96.97 ml/mol and 4.97 ml/mol, respectively, while the reaction volume for the substrate binding (${\Delta}V_{K_m^-1}$) was -101.94 ml/mol. The large negative ${\Delta}V^{\neq}$ for the overall reaction indicated that the pressurization of glutamate racemase resulted in enhanced catalytic efficiencies. In addition, this value was also due to the large negative ${Delta}V_{K_m^-1}$ for the substrate binding. The negative value of ${Delta}V_{K_m^-1}$ implied that the conformational changes in the enzyme molecule occurred during the substrate binding process, thereby increasing the degree of hydration. The small value of ${{Delta}V_{cat}}^{\neq}$suggested that the pressure did not affect the glutamate racemase catalysis after the substrate binding.

• 상하수도학회지
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• 제18권5호
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• pp.656-665
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• 2004

An Ozone reaction model combined with CFD(Computational Fluid Dynamics) technique was developed in this research, in the simulation of ozonation, hydrodynamic behavior as well as reaction model is important because ozone is supplied to treated water as gas ozone. In order to evaluate hydrodynamic behavior in an ozone contactor, CFD technique was applied. CFD technique elucidated hydrodynamic behavior in the selected ozone contactor, which consisted of three main chambers. Three back-mixing zones were found in the contactor. The higher velocities of water were observed in the second and third compartments than that in the first compartment. The flow of the opposite direction to the main flow was observed near the water surface. Based on the results of CFD simulation, the ozone contactor was divided into small compartments. Mass balance equations were established were established in each compartment with reaction terms. This reaction model was intended to predict dissolved ozone concentration, especially. We concluded that the model could predict favorably the mass balance of ozone, namely absorption efficiency of gaseous ozone, dissolved ozone concentration and ozone consumption. After establishing the model, we discussed the effect of concentration of gaseous ozone at inlet, temperature and organic compounds on dissolved ozone concentration.

• 한국수자원학회논문집
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• 제33권1호
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• pp.73-85
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• 2000

농촌 소하천의 수리학적 및 수질특성을 반영한 모형을 개발하였다. 모형구조 설계시 제어체적 기법을 활용하여 하천 형상, 수질 및 유량의 변화가 심한 농촌 유역의 소하천에 대한 수질의 모의하였다. 개발한 모형에 난수발생기법을 도입하여 최적 반응계수와 모형구조를 추정하였다. 또한 모형 보정기준의 일반화를 위해 동의지표와 효율계수를 도입하여 매개변수추정의 신뢰성 향상을 도모했다. 모형의 적용성을 검증하기 위해 경남 김해시 한림면 용덕천에서 수질을 채취하여 분석하였다. 관측된 자료와 개발된 모형의 비교연구를 통해 대상유역의 소하천에서 일어나는 수질 반응계수들과 그 변동성을 추정하였다.

• Nuclear Engineering and Technology
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• 제4권3호
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• pp.186-193
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• 1972

Rose $Bengal-^{131}$ /I, $Hippuran-^{131}$ /I, $H.S.A-^{131}$ /I 등을 효과적으로 합성하기 위해 표지 반응액의 pH, 염의함량, 반응액중의 완충용액의 부피 및 합성장치등에 따르는 표지 반응수율을 검토하였다. Rose $Bengal-^131{ }$I 및 $Hippuran-^{131}$ /I 의 반응수율은 PH 5.6에서, $H.S.A-^{131}$ /I 반응수율은 pH 8.5에서 각각 가장 좋았다. 반응액중에 함유된 염은 $Hippuran-^{131}$ /I의 생성반응을 크게 저해 시켰으며 H.S.A.의 표지수율은 어느 범위안에서 오히려 약간 향상시켰다. Rose $Bengal-^{131}$ /I 나 $Hippuran-^{131}$ /I 를 소규모 합성할 경우는 밀폐된 용기가 효과적이었다. 이상의 결과에 따라 더 높은 표지수율과 좋은 재현성을 얻을 수 있는 반응조건을 확립하였으며 이에 따라 환원제가 함유된 국산 $Na^{131}$ /I를 사용하더라도 Rose $Bengal-^{131}$ /I과 $Hippurn=^{131}$ /I의 표지수율을 높일 수 있었다.

• Computers and Concrete
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• 제16권1호
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• pp.37-48
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• 2015

Alkali aggregate reaction affects numerous civil engineering structures and causes irreversible expansion and cracking. This work aims at developing model to predict the potential expansion of concrete containing alkali-reactive aggregates. First, the paper presents the experimental results concerning the influence of particle size of an alkali-reactive aggregate on mortar expansion studied at 0.15-0.80 mm, 1.25-2.50 mm and 2.5-5.0 mm size fractions and gives data necessary for model development. Results show that no expansion was measured on the mortars using small particles (0.15-0.80 mm) while the particles (1.25-2.50 mm) gave the largest expansions. Finally, model is proposed to simulate the experimental results by studying correlations between the measured expansions and the size of aggregates and to calculate the thickness of the porous zone necessary to take again all the volume of the gel created by this chemical reaction.