• 한국환경과학회지
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• 제24권4호
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• pp.461-470
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• 2015

As hydrogeologic parameters such as hydraulic conductivity and specific yield are estimated by aquifer test, these are dependent on specific points at which field test was conducted. To overcome these site-specific limitations, a method of estimating transmissivity of aquifer using distribution features for parameters in Water table fluctuation model is newly suggested. Distribution features in reaction factor, specific yield and transmissivity having the function of pore space in aquifer are used to derive empirical equation for estimating transmissivity. From the result for applying the equation for 10 groundwater stations in Northeast Jeju Island, this equation is available for estimating transmissivity compared to the value estimated by existing equations. The estimated transmissivity ranged from 14.2 to $3,716.9m^2/day$, and its average was $821.8m^2/day$.

• Preventive Nutrition and Food Science
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• 제1권1호
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• pp.41-45
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• 1996

This study was conducted to develop the fermentation kinetic model for the prediction of acidity and pH changes in Kimchi as a function of fermentation temperatures. The fitness of the model was evaluated using traditional two-step method and an alternative non-linear regression method. The changes in acidity and pH during fermentation followed the pattern of the first order reaction of a two-step method. As the fermentation temperature increased from 4$^{\circ}C$ to 28, the reaction rates of acidity and pH were increased 8.4 and 7.6 times, respectively. The activation energies of acidity and pH were 16.125 and 16.003kcal/mole. The average activation energies of acidity and pH using a non-linear method were 16.006 by the first order and 15.813 kcal/mole by the zero order, respectively. The non-linear procedure had better fitting 개 experimental data of the acidity and pH than two-step method. The shelf-lives based on the time to reach the 1.0% of acidity were 33.1day at 4$^{\circ}C$ and 2.8 day 28$^{\circ}C$.

• Korean Chemical Engineering Research
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• 제59권3호
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• pp.467-479
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• 2021

Abstract: A kinetic model was developed for the dehydration of ethanol to ethylene based on two parallel reaction pathways. Kinetic parameters were estimated by fitting experimental data of powder catalysts in a lab-scale test, and the effectiveness factor was determined using data from pellet-type catalysts in bench-scale experiments. The developed model was used to design a multitubular fixed-bed reactor (MTR) and an adiabatic reactor (AR) at a 10 ton per day scale. The two different reactor types resulted in different process configurations: the MTR consumed the ethanol completely and did not produce the reaction intermediate, diethyl ether (DEE), resulting in simple separation trains at the expense of high equipment cost for the reactor, whereas the AR required azeotropic distillation and cryogenic distillation to recycle the unreacted ethanol and to separate the undesired DEE, respectively. Quantitative analysis based on the equipment and annual energy costs showed that, despite high equipment cost of the reactor, the MTR process had the advantages of high productivity and simple separation trains, whereas the use of additional separation trains in the AR process increased both the total equipment cost and the annual energy cost per unit production rate.

• Nuclear Engineering and Technology
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• 제55권9호
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• pp.3194-3201
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• 2023

In water-cooled power reactor, hydrogen is generated in case of steam zirconium reaction during severe accident condition and later on in addition to hydrogen; CO is also generated during molten corium concrete interaction after reactor pressure vessel failure. Passive Autocatalytic Recombiners (PARs) are provided in the containment for hydrogen management. The performance of the PARs in presence of hydrogen and carbon monoxide along with air has been evaluated. Depending on the conditions, CO may either react with oxygen to form carbon dioxide (CO2) or act as catalyst poison, reducing the catalyst activity and hence the hydrogen conversion efficiency. CFD analysis has been carried out to determine the effect of CO on catalyst plate temperature for 2 & 4% v/v H₂ and 1-4% v/v CO with air at the recombiner inlet for a reported experiment. The results of CFD simulations have been compared with the reported experimental data for the model validation. The reaction at the recombiner plate is modelled based on diffusion theory. The developed CFD model has been used to predict the maximum catalyst temperature and outlet species concentration for different inlet velocity and temperatures of the mixture gas. The obtained results were used to fit a correlation for obtaining removal rate of carbon monoxide inside PAR as a function of inlet velocity and concentrations.

• 대한화학회지
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• 제47권3호
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• pp.191-198
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• 2003

Pairwise Energy Model(PEM)은 A+BC$\{leftrightarrow}$AB+C(여기서 B와 C는 수소의 동위원소)반응의 반응 cross section은 A와 B사이의 pairwise energy Es에만 의존 한다고 가정한다. PEM은 지금까지 $O(^3P)+HD,\;Ar^++(H_2,\;D_2,및\;HD)$등 여러 반응에 대한 동위원소 효과를 이론적으로 설명하는데 이용되어 왔다. 본 논문에서는 quasiclassical trajectory 방법을 이용하여 $Cl+H_2$와 Cl+HD 반응을 계산하였고 높은 충돌에너지에서 이들 반응들의 결과를 PEM을 이용하여 잘 설명할 수 있었다. PEM을 이용하여 $Cl+H_2$ 반응의 cross section 값으로부터 높은 충돌에너지에서 Cl+HD 반응의 동위원소 효과를 정확히 예측할 수 있었다. 이러한 이유를 설명하기 위하여 생성물의 내부에너지 분포도 $P(E_{int})$를 조사 했다. 생성물의 내부에너지 분포도 $P(E_{int})$는 고정된 충돌에너지 E에서 동위원소 조합에 따라 다르지만 고정된 Es 값에서는 동위원소 조합에 대해서도 근사적으로 같다. 이것이 바로 PEM으로 이들 반응을 잘 설명해 줄 수 있는 이유이다. 여기서 도출된 결론은 높은 충돌에너지에서 여러 A+BC 반응에 또한 적용될 수 있을 것이다.

• 항공우주기술
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• 제11권1호
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• pp.126-134
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• 2012

본 논문을 통해 로켓 연소후류 전산해석에 적합한 단일화학종 비반응 해석 모델을 소개하였다. 이 모델의 기본적 개념은 고온 공기에 대한 동결 유동해석 기법에서 출발하였으나, 연소 후류에 대한 CEA 해석을 통해 구한 분자량 및 비열 값의 보정을 통해 동결 유동해석의 단점을 보완하였다. 단일화학종 비반응 해석모델과 유한속도 화학반응 해석 모델의 비교를 통해, 유사한 해석 결과를 얻는데 비반응 모델이 해석시간을 약 1/5 정도로 감소할 수 있음을 확인하였다.

• 한국ITS학회 논문지
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• 제8권5호
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• pp.48-56
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• 2009

현재 사회적으로 선팅에 대한 규제가 논란이 되고 있으나 이를 뒷받침할 만한 공학적인 근거가 부족한 실정이다. 선행연구에 따르면 과도한 선팅차량이 추종차량의 가감속등에 영향을 미쳐 용량저해 요인으로 작용할 수도 있다는 가설을 확인하였으나, 자료의 한계로 추종모델와 연결된 분석은 이루어지지 못하였기 때문에 추가연구가 필요하다. 이에 본 연구에서는 RTK-GPS를 이용하여 자료를 수집하였으며, 선두차량의 차량선팅 암도에 따라 후방차량에 미치는 영향을 차량추종 모델의 파라메터 변화를 통해 분석하였다. 본 논문에서는 가시광선 투과율에 따른 차두거리, 가속소음, 민감도, 반응시간을 분석하였다. 추종모델의 기본식인 GM 1모델 뿐만 아니라, 차량의 차두거리까지 고려된 GM 3모델에 적용시켜 민감도를 분석하였다. GM의 3모델 역시 1모델과 동일한 패턴의 결과로 도출되었으며, 선두차량의 선팅정도가 클수록 후방차량에 미치는 영향이 더 커지며, 선두차량의 선팅으로 인한 위험도는 2번째 차량보다 3번째 차량이 더 큰 것을 확인하였다. 차량의 선팅정도에 따라 교통류 안정성에 미치는 영향 분석에 관한 연구는 향후 과제로 남긴다.

• Ocean Systems Engineering
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• 제4권4호
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• pp.263-278
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• 2014

The spudcan requires the suitable design considering the soil, platform, and environmental conditions. Its shape needs to be designed to secure sufficient reaction of soil so that it can prevent overturning accidents. Its shape also has to minimize the installation and extraction time. Even in the same soil condition, the reaction of soil may be different depending on the shape of spud can, mainly the slope of top and bottom plates. Therefore, in this study, the relation between the slope of plates and the reaction of soil with and without water jetting is analyzed to better understand their interactions and correlations. For the investigation, a wind turbine installation jack-up rig (WTIJ) is selected as the target platform and the Gulf of Mexico is considered as the target site. A multi layered (sand overlying two clays) soil profile is applied as the assumed soil condition and the soil-structure interaction (SSI) analysis is performed by using ANSYS to analyze the effect of the slope change of the bottom plate and water jetting on the reaction of soil. This kind of investigation and simulation is needed to develop optimal and smart spudcan with water-jetting control in the future.

• 한국학교ㆍ지역보건교육학회지
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• 제13권3호
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• pp.13-31
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• 2012

Purpose: This study was on the structural analysis of the covariant amount in order to evaluate the suitability of the structural models which can explain and predict the mental health of children on the basis of Bronfenbrenner's ecological theory. Methods: A questionnaire was used to survey 269 children from dysfunctional families out of 5th and 6th grade students from 30 elementary schools in one city and 6 counties, which was analyzed by using PASW Statistics 18.0 and LISREL 8.7 programs. Results: The variable which had influence on the self-esteem was the social support. The variable which had influence on the positive reaction under stress was the stress. The variables which had influence on the negative reaction under stress were stress, and self esteem. The variables which had influence on the mental health were the self-esteem and the negative reaction under stress. The main variables to influence the mental health of children from dysfunctional families turned out to be the self-esteem and the negative reaction under stress to the mental health. Conclusion: Evaluating the suitability of the models, I presented the bases on the practical nursing business. They showed the right directions to the mental health care of children from dysfunctional families.

• 대한화학회지
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• 제41권1호
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• pp.22-46
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• 1997

25℃와 35℃에서 메탄올-아세토니트릴 혼합용매계에 대한 할로겐화 펜아실과 피리딘 치환체와의 친핵성치환반응을 속도론적으로 연구하였다. 전이상태 파라미터인 ΔH≠와 ΔS≠ 및 Brosted β값으로 보아 $S_N2$반응 메카니즘을 예상할 수 있었고, 이탈기 변화에 따른 QM모형의 적용으로 이들 반응의 전이상태 역시 생성물 닮은 구조임을 알 수 있었다.