• Clean Technology
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• v.18 no.3
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• pp.320-324
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• 2012

In the present study, the discharge characteristics of a lithium-ion battery was evaluated to calculate the rate of heat generation under various discharge rates by mathematical modeling. The modeling and simulation of a pseudo-two dimensional ionic transport system for governing Butler-Volmer equation were carried out by using FEMLAB as a PDE (partial differential equation) solver, where the discharge rate was changed from 5 $A/m^2$ to 25 $A/m^2$. The computational results showed that the concentration of consumed solid-phase lithium at the surface of electrode was increased with increasing discharge rates. While the resulting diffusion limitation occurred shortly, it increased the rate of heat generation even more rapidly for the internal voltage to approach the cutoff voltage of the lithium-ion battery.

• Clean Technology
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• v.10 no.1
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• pp.9-17
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• 2004

Direct methanol fuel cell(DMFC) with proton exchange membrane (PEM) has advantages over the conventional power source (e.g. vehicle). DMFC, however, has a problem to be solved such as methanol crossover, high anodic overpotential and limiting current density, etc. The physicochemical phenomena in DMFC can be described by coupled PDEs (partial differential equations), which can be solved by a PDE solver. In this paper, we utilized a commercial software FEMLAB to solve the PDEs. The FEMLAB is one of the software programs available which are developed as a solver for building physics problems based on PDEs and is designed to simulate systems of coupled PDEs which may be 1D, 2D, 3D, non-liner and time dependent. We performed simulation using the Tafel equation as an electrochemical reaction model to analyze methanol concentration profile in DMFC system. We confirm that the rapid decrease of methanol concentration at anodic catalyst layer with the increase of the current density is a main reason of the low performance in DMFC through simulation results.

• KSBB Journal
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• v.21 no.3
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• pp.224-229
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• 2006

FEMLAB is a powerful interactive environment for modeling, solving all kinds of scientific and engineering problems based on partial differential equations(PDEs). Separation process of chiral compound in HPLC columns was simulated by FEMLAB. To study change of elution profile with isotherm models, non-competitive and competitive Langmuir adsorption isotherm were adopted. Separated material was (R, S)-ibuprofen [(R, S)-2-(4-isobutyl phenyl) propionic acid], an anti-inflammatory agent, which retain the pharmacological activity in the (S)-(+)-enantiomer. Sample concentrations were changed from 0.5 mg/ml to 2.0 mg/ml at a flow rate of 1 ml/min and flow rate varied from 1 ml/min to 3 ml/min at an ibuprofen concentration of 2.0 mg/ml and $20{\mu}l$ of injection volume. Simulated results were well fitted with experimental data.

• International Journal of Safety
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• v.6 no.2
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• pp.22-26
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• 2007

An episode of corona is a heterogeneity-caused electric discharge that occurs when electric fields are formed layer on layer and concentrated on an electrode. Electric wires built at the tip of 154kV private facilities use dead end clamp spawns corona from homogeneity caused by field concentration. Corona induces power loss, noise, insulator failure and more. In this research, we've studied the characteristics of coronas that take place in porcelain insulators and terminal electric wires of supporting hard wares (dead end clamp) that are set up as spares in the 154kV private facilities use hydroelectricity installations to support electric wires. Corona, which cannot be identified by regular methods, was measured utilizing UV image camera. As the result of measuring corona via UV image camera, we've confirmed that the depletion of insulators was accelerated following the wire end treatment method and validated the stress intensity of insulators at various lengths of bare wires caused by electric fields via FEMLAB. We have also proposed a new model for relieving homogeneity-caused field concentration, and after analyzing the proposed model via FEMLAB, we've confirmed that the concentration of field distribution was indeed reduced. Such results are exploited in installation of private facilities use equipments, maintenance of insulators and hard wares as well as safety enhancement, and are anticipated to be effectively utilized in corona prevention measures.

• International Journal of Safety
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• v.7 no.1
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• pp.21-25
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• 2008

The occurrence of a corona is that electrical discharge due to the heterogeneity that occurs when an electrical field is concentrated in an electrode due to a cusp formed on said electrode. Wire treatment at the end of a 154kV dead end clamp for end users accelerates the occurrence of corona, which in turn leads to power loss and noise. In this study, the characteristics of the corona which occurs between porcelain insulators and support clamps of overhead lines used in l54kV power receiving facilities for end users were investigated. The corona, which cannot be identified by one common method, was measured utilizing a UV image camera. A risk assessment for fire damage and its status was suggested. The stress distribution of the electrical field by length of bare wire was suggested by means of the finite element method (FEMLAB). As a result, it was found to affect a porcelain insulators. These results can be utilized for the enhancement of clamp installation and safety in power facilities.

• Journal of the Korean Electrochemical Society
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• v.9 no.4
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• pp.151-157
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• 2006

A two-dimensional numerical model to study the performance of anode-supported flat-tube solid oxide fuel cell (SOFC) far the cross section of the cell in the flow direction of the fuel and air flows is developed. In this model a mass and charge balance, Maxwell-Stefan equation as well as the momentum equation by using, Darcy's law are applied in differential form. The finite element method using FEMLAB commercial software is used for meshing, discritization and solving the system of coupled differential equations. The current density distribution and fuel consumption as well as water production are analyzed. Experimental data is used to verify a predicted voltage-current density and power density versus current density to judge on the model accuracy.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.559-559
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• 2005

• Journal of Energy Engineering
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• v.20 no.4
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• pp.278-285
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• 2011

Computational modelling and simulation for the charge-discharge characteristics of Lithium-ion batteries have been carried out. The battery system consists of a simplified 2-dimensional single cell for the modelling, in which the thermal modelling on the charge-discharge characteristics was conducted in the temperature range from 288 K through 318 K by using FEMLAB as an engineering PDE solver. While material parameters adopted in the present modelling were dependent on the system temperature, their thermal modelling were applied on the simulations of the charge-discharge period and the rate of transferring charges systematically. The resulting simulation shows that the cycle of the charge-discharge shorten itself by reducing the system temperature, regardless of the charge-discharge rates. In addition, the mass-transport phenomena of Lithium ion have been discussed in connection with the charge-discharge characteristics in the battery.

• Clean Technology
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• v.12 no.4
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• pp.211-216
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• 2006

In this study, we investigated the potential changes in the cross sectional area of the rectangular microchannel with various zeta potentials and hydraulic diameters. We changed height/width ratio as 1, 1/2, and 1/3 and investigated its effect on the potential change. For this research, FEMLAB(Comsol, verson 3.0) was used to investigate the theoretical potential distribution. The potential changes in the cross section shows that right and left surfaces affect to some ranges. For the same area and shape, the potential value is directly proportional to the zeta potential change. With the decrease in the H/W ratio, the electrical double layer is condensed to the side surfaces.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.335-338
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• 2005

Starting with the development of environmentally friendly electric controlled engine, sensors have played an increasing role in automotive technology. Electric power steering (EPS) systems are more and more replacing hydraulic systems. To improve fuel economy, the power assistance is provided by an electric drive. In this paper, development of a unique torque sensor for EPS is introduced. A capacitive type torque sensor is concluded to be suitable for EPS because its output is accurate, linear and robust against the variance of temperature, and patents have not applied so much.