• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3377-3382
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• 2007

In proton exchange membrane fuel cell, the heat is generated at the catalyst layer as result of exothermic electrochemical reaction. This heat increases temperature of gas diffusion layer and membrane whose conductivity is very sensitive to humidity, function of temperature. So it is very important to analysis heat transfer through fuel cell to maintain temperature at specified range. In this paper numerical simulation was done including reversible, irreversible, ionic resistance, water formation loss to source term of energy equation. Results show that irreversible and water formation loss contributes mainly to energy source term and as current density increases, all of energy source terms become increased and Nusselt number is increased as results of more heat generation. Particularly irreversible loss is found to be predominant among the all energy source and water formation at cathode channel influences the temperature distribution of fuel cell greatly.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.4
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• pp.328-333
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• 2014

A hybrid particle-mesh method based on the vorticity-velocity formulation for solving the incompressible Navier-Stokes equations is a combination of the Vortex-In-Cell(VIC) method for convection and the penalization method for diffusion. The key feature of the numerical methods is to determine velocity and vorticity fields around a solid body on a temporary grid, and then the time evolution of the flow is computed by tracing the convection of each vortex element using the Lagrangian approach. Assuming that the vorticity and velocity fields are to be computed in time domain analysis, pressure fields are estimated through a complete set of solutions at present time step. It is possible to obtain vorticity and velocity fields prior to any pressure calculation since the pressure term is eliminated in the vorticity-velocity formulation. Therefore, pressure field is explicitly treated by solving a suitable Poisson equation. In this paper, we propose a simple way to numerically implement the vorticity-velocity-pressure formulation including a penalty term. For validation of the proposed numerical scheme, we illustrate the early development of viscous flows around an impulsive started circular cylinder for Reynolds number of 9500.

• Journal of Information Technology Applications and Management
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• v.16 no.4
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• pp.109-134
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• 2009

Compared to research on the success of IT projects in general, research on the management of conflict in IT teams and its impact on project success is insufficient. This research performed a comparative study to analyze the nature and evolving phenomenon of conflicts in IT project teams. This study aimed at; First, Why a conflict is created within and around an IT project team. Second, What is the phenomenon of conflict evolution, diffusion, and/or resolution? Third, How the differences in conflict management style affects the IT project performance? Three propositions were drawn from the analysis of two intensive analysis of conflict cases and their comparison. Proposition 1 : Both 'the method of pointing out a problem' and 'the pointed-out contents' can be the trigger of conflicts around an IT project. Proposition 2 : While the focus of attention of one party is 'the method of pointing out a problem', if the other's and focus of attention of one party is 'the pointed-out contents', that is, if the focus of attention mismatch, the conflict can be amplified. Proposition 3 : According to the temporal nature of the relationship, e.g., short-term versus long-term, the way people approach and deal with the conflict differs.

• Proceedings of the Korea Database Society Conference
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• 2010.06a
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• pp.109-123
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• 2010

Compared to research on the success of IT projects In general, research on the management of conflict in IT teams and its impact on project success is insufficient. This research performed a comparative study to analyze the nature and evolving phenomenon of conflicts in IT project teams. This study aimed at; First, Why a conflict is created within and around an IT project team. Second, What is the phenomenon of conflict evolution, diffusion, and/or resolution? Third, How the differences in conflict management style affects the IT project performance? Three propositions were drawn from the analysis of two intensive analysis of conflict cases and their comparison. Proposition 1 : Both 'the method of pointing out a problem' and 'the pointed-out contents' can be the trigger of conflicts around an IT project. Proposition 2 : While the focus of attention of one party is 'the method of pointing out a problem', if the other's and focus of attention of one party is 'the pointed-out contents', that is, if the focus of attention mismatch, the conflict can be amplified. Proposition 3 : According to the temporal nature of the relationship, e.g., short-term versus long-term, the way people approach and deal with the conflict differs.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.11a
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• pp.171-172
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• 1996

Cocaine is a powerful reinforcer that has become a popular drug of abuse in man. CNS effects that are related to the abuse of cocaine include feeling of well-being and euphoria. Brain dopamine systems are thought to mediate reinforcement and it is often assumed that cocaine's inhibition of dopamine uptake is the mechanism underlying its reinforcing effects. With increase in cocaine use among general population in recent years, adverse effects of the drug have occurred in all social strata and age groups. Therefore, it has been recognized that the epidemic of cocaine abuse is a growing major concerning public health. One of the most troubling aspects of cocaine abuse is its use by pregnant women. Drug abuse during pregnancy puts two lives at risk. Cocaine produces toxic effects on the fetus at concerntrations that are apparently nontoxic to the mother. Not only does cocaine cross the placenta via diffusion and via rapid penetration to mucous membranes, due to its high lipid solubility, but cocaine can also be found in breast milk, the effects of the cocaine can persist long after the child is born. Although it is known that prenatal cocaine exposure is associated with developmental risk to the fetus ana newborn, few studies have been conducted to assess the mechanisms whereby either short-term or long-term administration of cocaine can exert its harmful effects on the mother or the child. Therefore, it was our great interest to investigate the pharmacological and neurobehavioral changes in offspring that are prenatally exposed to cocaine.

• Nuclear Engineering and Technology
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• v.22 no.4
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• pp.315-325
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• 1990

The analytical repository source term (REPS) computer code is developed for the safety assessment of radioactive waste geologic repository. For reliable prediction of the leach rates for various radionuclides, degradation of concrete structures, corrosion rate of waste container, degree of corrosion on the container surface, and the characteristics of radionuclides are considered in this REPS code. For the validation of the radionuclide leach rates predicted by the REPS model, the calculated leach rates of Cs-137, Sr-85, and Co-60 are compared with two reported leaching test results. Cesium and strontium leach congruently, and the leaching test results of these species can be reproduced by the congruent leaching model included in the REPS model. In case of cobalt, the solid diffusion model is in good agreement with the leaching test results.

• Korean Membrane Journal
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• v.6 no.1
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• pp.55-60
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• 2004

In recent years, an increasing interest in membrane technology has been observed in chemical and environmental industry. Membrane technology has advantages of low cost, energy saving and environmental clean technology comparing to conventional separation processes. Pervaporation is one of new advanced membrane technology applied for separation of azeotropic mixtures, aqueous organic mixtures, organic solvent and petrochemical mixtures. Sodium alginate composite membranes were prepared for the enhancement of long-term stability of pervaporation performance of water-ethanol mixture using pervaporation. Sodium alginate membranes were crosslinked with CaCl$_2$ and coated with polyelectrolyte chitosan to protect washing out of calcium ions from the polymer. The surface structures of PAN and hydrolysed PAN membrane were confirmed by ATR Fourier transform infrared (FT-IR). A field emission scanning electron microscopy (FE-SEM; Jeol 6340F) operated at 15 kV. Concentration profiles for Ca in the membrane surface and membrane cross-section were taken by an energy dispersive X-ray (EDX) analyser (Jeol) attached to the field emission scanning electron microscopy (Jeol 6340F). Pervaporation experiments were done with several operation run times to investigate long-term stability of the membranes.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.2
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• pp.205-214
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• 2021

Currently, the interim storage pools of spent fuels in South Korea are expected to become saturated from 2024. It is required to prepare an operation plan of a domestic dry storage facility during a long-term period, with the researches on safety evaluation methods. This study modified the FRAPCON code to predict the spent fuel integrity evaluation such as the axial cladding temperature, the hoop stress and hydrogen distribution in dry storage. The cladding temperature in dry storage was calculated using the COBRA-SFS code with the burnup information which was calculated using the FRAPCON code. The hoop stress was calculated using the ideal gas equation with spent fuel information such as rod internal pressure. Numerical analysis method was used to calculate the degree of hydrogen diffusion according to the hydrogen concentration and temperature distribution during a dry storage period. Before 50 years of dry storage, the cladding temperature and hoop stress decreased rapidly. However, after 50 years, they decreased gradually and the cladding temperature was below 400 K. The initial temperature distribution and hydrogen concentration showed a parabolic line, but hydrogen was transferred by the hydrogen concentration and temperature gradient over time.

• Biomedical Science Letters
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• v.25 no.1
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• pp.32-39
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• 2019

Conventional high-flux hemodialysis (HD) is not as good as normal kidney function. Morbidity and mortality rates of patients receiving HD are still very high. To increase mid-to-large molecule clearance by combining diffusion and convection, on-line hemodiafiltration (HDF) is required. The objective of this study was to compare long-term survival rate of patients treated with on-line HDF to those who received conventional high-flux HD by reviewing data from Chonnam National University Hospital (CNUH). We selected patients who attended the 'CUNH dialysis center' and agreed to participate in the study. Overall, 40 patients with ESRD switched from high flux HD to on-line HDF or started on-line HDF from August 2007 to December 2009. Additionally, a total of 42 patients receiving conventional high-flux HD during the same period were enrolled. We then reviewed long-term survival rate of patients receiving on-line HDF over the next seven years. When we compared survival rates for seven years, the survival rate of the group receiving on-line HDF was 65% (26/40) while that of the group receiving the conventional high-flux HD was 54.8% (23/42). Although the number of patients was small to see survival difference clearly by one specific dialysis modality, there was somewhat difference in survival rate between the two groups. Indicators such as anemia, calcium-phosphate metabolism, nutritional status, treatment adequacy, and hospitalization were also improved in the group receiving HDF. Overall, results of our study showed beneficial effects of on-line HDF on clinical outcomes and survival in chronic HD patients.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.2
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• pp.151-164
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• 2021

The paper identifies the enablers (drivers) and inhibitors (barriers) influencing e-customs implementation in Vietnam (known as a developing country with a lower technological environment) along with determining the impact of e-customs on firm performance. The survey was conducted with the representatives (managers) of firms in five cities and provinces dominating Vietnam's international trade. The data was analyzed using structural equation modeling (SEM). The findings show two significant drivers (enablers) - relative advantages and national culture, while compatibility and ease of use are the barriers. Previous studies showed that cultural dimensions related to 'uncertainty acceptance' and 'individualism' encourage innovation; however, this paper demonstrates that 'uncertainty avoidance' and 'collectivism' promote e-customs deployment in Vietnam. Previously, Vietnamese culture was known for scoring high on cultural dimensions related to 'power distance' and 'short-term orientation'. However, today, as an emerging country, Vietnamese has switched to 'low distance' and 'long-term orientation', especially in terms of e-customs innovation. Additionally, the paper also emphasized that e-customs implementation had a positive influence on firm performance in Vietnam. Based on the results of the paper, policy-makers can devise essential solutions to enhance e-customs implementation as well as managers of firms can set-up strategies to adapt to the modernized environment.