• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.156-163
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• 2015

The fuel cells have been investigated in the applications of marine as the high efficient and eco-friendly power generating systems. In this study, modeling of IR Type molten carbonate fuel cell (Internal Reforming Type molten carbonate fuel cell) has been developed to analyze the feasibility of thermal energy utilization. The model is developed under Aspen plus and used for the study of system performances over regarding fuel types. The simulation results show that the efficiency of MCFC system based on NG fuel is the highest. Also, it is also verified that the steam reforming is suitable as pre-reforming for diesel fuel.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3140-3141
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• 2008

The output power efficiency of the fuel cell system depends on the demanded current, stack temperature, air excess ratio, hydrogen excess ratio and inlet air humidity. Thus, it is necessary to determine the optimal operation condition for maximum power efficiency. In this paper, we developed a dynamic model of fuel cell system which contains mass flow model, diffusivity gas layer model, membrane hydration and electrochemistry model. In order to determine the maximum output power and minimum use of hydrogen in a certain power condition, response surface methodology (RSM) optimization based on the proposed PEMFC stack model is presented. The results provide an effective method to optimize the operation condition under varied situations.

• Proceedings of the KAIS Fall Conference
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• 2004.11a
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• pp.272-273
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• 2004

Filter media are one of themost important choices when bilfiltration is applied. Filter media provide adsorbing microbes with available sites for residence and the residential cells grow to degrade or decompose target waste gases. Up to date, filter media were only qualitatively analyzed. As a quantitative approach to filter material for biofiltration, a simple model based on reaction kinetics and mass action law (Ottengraf's Model in 1983) was presented. Cork, zeolite, and granulated activated carbon were tested in terms of effective surface area, cell covered fraction of adsorbing sites, surface roughness, and pore size distribution. The cell covered fraction, surface roughness and hydrophilicity was found to be closely related to the efficiency of gas degradation in biofiltration. The cork was the best candidate for cell residence and growth in this work.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.3
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• pp.107-116
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• 2005

The paper addresses modeling and analysis of a grid-connected photovoltaic generation system (PV system). PSCAD/EMTDC, an industry standard simulation tool for studying the transient behavior of electric power system and apparatus, is used to conduct all aspects of model implementation and to carry out extensive simulation study. This paper is aimed at sharing with the PSCAD/EMTDC user community our user-defined model for PV system applications, which is not yet available as a standard model within PSCAD/EMTDC. An equivalent circuit model of a solar cell has been used for modeling solar array. A series of parameters required for array modeling have been estimated from general specification data of a solar module. A PWM voltage source inverter (VSI) and its current control scheme have been implemented. A maximum power point tracking (MPPT) technique is employed for drawing the maximum available energy from the PV array. Comprehensive simulation results are presented to examine PV array behaviors and PV system control performance in response to irradiation changes. In addition, dynamic responses of PV array and system to network fault conditions are simulated and analysed.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.26-37
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• 2012

Multi-dimensional hydrodynamic and water quality models are widely used to simulate the physical and biogeochemical processes in the surface water systems such as reservoirs and estuaries. Most of the models have adopted the Eulerian grid modeling framework, mainly because it can reasonably simulate physical dynamics and chemical species concentrations throughout the entire model domain. Determining the optimum grid cell size is important when using the Eulerian grid-based three-dimensional water quality models because the characteristics of species are assumed uniform in each of the grid cells and chemical species are represented by concentration (mass per volume). The objective of this study was to examine the effect of grid-size of a three dimensional hydrodynamic and water quality model (EFDC) on hydrodynamics and mass transport in the Saemangeum Reservoir. Three grid resolutions, respectively representing coarse (CG), medium (MG), and fine (FG) grid cell sizes, were used for a sensitivity analysis. The simulation results of numerical tracer showed that the grid resolution affects on the flow path, mass transport, and mixing zone of upstream inflow, and results in a bias of temporal and spatial distribution of the tracer. With the CG, in particular, the model overestimates diffusion in the mixing zone, and fails to identify the gradient of concentrations between the inflow and the ambient water.

• Journal of the Korean Magnetic Resonance Society
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• v.20 no.4
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• pp.129-137
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• 2016

Transmembrane(TM) proteins are closely related to transport, channel formation, signaling, cell to cell interaction, so they are the crucial target of modern medicinal drugs. In order to study the structure and function of these TM proteins, it is important to prepare reasonable amounts of proteins. However, their preparation is seriously difficult and time-consuming due to insufficient yields and low solubility of TM proteins. We tried to produce large amounts of Syndecan-4 containing TM domain(SDC4-TM) that is related to the wound healing and tumor. Also, mutated SDC4-TM was studied to investigate structural change by modification of dimerization motif. We performed the structure determination by the Polarity Index at Slanted Angle (PISA) wheel pattern analysis based on $^{15}N-^1H$ 2D SAMPI-4 solid-state NMR of SDC4-TM and computational modeling using Discovery Studio 2016.

• KSBB Journal
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• v.14 no.4
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• pp.414-421
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• 1999

The influenced of light intensity, cell density, and light pathlength on photosynthetic activity of Chlorella vulgaris were investigated. Since the light respon curve varied according to reaction conditions, the parameters estimated from nonlinear regression were proved to be apparent and could not be applied to various situations. The light response model incorporating the light penetration through the microalgal suspension was developed based upon the spatial distribution of the photosynthetic activity. This model showed a good agreement with experimental data at different cell densities and light intensities. Using the model the effects of cell density and light pathlenth were simulated and some dicussions about optimization of operation conditions of photobioreactors were carried out. Concludingly, the developed model can be useful for predicting microalgal photosynthesis and for determining the optimal operating conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.3
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• pp.397-403
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• 2013

The demand for eco-friendly and higher fuel economy vehicles has helped develop eco-friendly and fuel-efficient vehicles such as hybrid vehicles. In a hybrid vehicle, the change in the battery charge after driving should be added to the fuel consumption as the equivalent fuel usage based on its own characteristics. Thus, the fuel efficiency of a hybrid vehicle cannot be improved simply by increasing the battery capacity. In this study, I attempt to improve the total fuel economy of a hybrid vehicle, including the equivalent fuel consumption, by modeling a fuel cell hybrid vehicle using Matlab Simulink, analyzing the usage zone of the fuel cell with the existing control strategy, and optimizing the power distribution of the battery and fuel cell in the main usage zone of the fuel cell.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.8 s.251
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• pp.731-740
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• 2006

The solid oxide fuel cell (SOFC) is expected to be a candidate for distributed power sources in the next generation, due to its high efficiency and high-temperature waste heat utilization. In this study, the 5-cell SOFC stack was operated with pure hydrogen or reformed gas at anode side and air at cathode side. When stack was operated with diesel and methane ATR reformer, the influence of the $H_2O/C,\;O_2/C$ and GHSV on performance of stacks have been investigated. The result shows that the cell voltage was decreased with the increase of $H_2O/C$ and $O_2/C$ due to the partial pressure of fuel and water, and cell voltage was more sensitive to $O_2/C$ than $H_2O/C$. Next, the dynamic model of SOFC system included with ATR reformer was established and compared with experimental data. Based on dynamic model, the operation strategy to optimize SOFC-Reformer system was suggested and simulated.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.184-190
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• 2014

Fuel cell power system, unlike conventional energy sources, converts chemical energy into electrical energy through electrochemical reaction of hydrogen and oxygen. In recent years, railway field as well as mobile fuel cell power system is being studying actively with development of hydrogen storage technologies. This paper presents the feasibility study on small-scale prototype electric railway vehicle application using fuel cell generation system. it is confirmed that proposed fuelcell-battery hybrid system shows good response characteristic about speed and torque based on design of parameter on system. Also as results of response for proposed system modeling, it show that powering mode and braking mode of system is controlled by switching devices of converters.