• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.567-570
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• 2000

Thermal simulation of typical stack-type and newly proposed planar-type micro-gas sensors were studied by FEM method. the thermal analysis for the proposed planar structure including temperature distribution over the sensing layer and power consumption of the heater were carried using finite element method by computer simulation and well compared with those of typical stack-type micro-gas sensor. The thermal properties of the microsensor from thermal simulation were compared with those of an actual device to investigate the acceptability of the computer simulation.

• Journal of IKEEE
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• v.23 no.1
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• pp.338-341
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• 2019

In this paper, we propose a novel ESD device with improved characteristics of LVTSCR, which is a representative ESD protection device, and verify the N-stack technology for design optimized for each required voltage of a specific application. The characteristics of the holding voltage and the trigger voltage, which are the main parameters, are examined and the temperature characteristic, which is an indicator of the tolerance characteristic, is also verified. well region and a parasitic NPN to form a series-connected structure. We used synopsys' T-cad simulation tool for characterization.

• Fire Science and Engineering
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• v.23 no.5
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• pp.143-152
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• 2009

The numerical analyses for each single simplified shaft with three type openings were carried out by using computational fluid dynamics model for the calculation of the pressure difference and the location of the neutral plane and the visualization of stack effect. As the height of shaft heighten, the pressure difference of stack effect is much deviated against the theoretical value. For the Type A models shorter than 30 m height of shaft and the Type B models longer than 30m, the simulation results for the location of the neutral plane are well agreed to the theoretical values with 5% less deviations just after the beginning of simulation (t = 10s). For the Type B models longer than 30m with multiple openings, therefore, it is possible to calculate the location of the neutral plane by using a CFD model. The phenomenon of the air flow of stack effect can be easily understood with the visualization of stack effect.

• Asian Journal of Atmospheric Environment
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• v.2 no.1
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• pp.1-13
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• 2008

A numerical simulation method has been developed to predict atmospheric flow and stack gas diffusion using a calculation domain of several km around a stack under complex terrain conditions containing buildings. The turbulence closure technique using a modified k-$\varepsilon$-type model under a non hydrostatic assumption was used for the flow calculation, and some of the calculation grids near the ground were treated as buildings using a terrain-following coordinate system. Stack gas diffusion was predicted using the Lagrangian particle model, that is, the stack gas was represented by the trajectories of released particles. The numerical model was applied separately to the flow and stack gas diffusion around a cubical building and to a two-dimensional ridge in this study, before being applied to an actual terrain containing buildings in our next study. The calculated flow and stack gas diffusion results were compared with those obtained by wind tunnel experiments, and the features of flow and stack gas diffusion, such as the increase in turbulent kinetic energy and the plume spreads of the stack gas behind the building and ridge, were reproduced by both calculations and wind tunnel experiments. Furthermore, the calculated profiles of the mean velocity, turbulent kinetic energy and concentration of the stack gas around the cubical building and the ridge showed good agreement with those of wind tunnel experiments.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.541-544
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• 2005

This study presents the integrated modeling approach to simulate the proton exchange membrane (PEM) fuel cell system for vehicle application. The fuel cell system consisting of stack and balance of plant (BOP) was simulated with MATLAB/Simulink environment to estimate the maximum system power and investigate the effect of BOP component sizing on system performance and efficiency. The PEM fuel cell stack model was established by using a semi-empirical modeling. To maximize the net efficiency of fuel cel1 system, multi-variable optimization code was adopted. Using this method the optimized operating values were obtained according to various system net power levels. The fuel cell model established was co-linked to AVL CRUISE, a vehicle simulation package. Through the vehicle simulation software, the fuel economy of fuel cell powered electric vehicle for two types of driving cycles was presented and compared. It is expected that this study tan be effectively employed in the basic BOP component sizing and in establishing system operation map with respect to net power level of fuel cell system.

• New & Renewable Energy
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• v.1 no.4 s.4
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• pp.43-48
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• 2005

This study presents the integrated modeling approach to simulate the proton exchange membrane [PEM] fuel cell system for vehicle application. The fuel cell system consisting of stack and balance of plant (BOP) was simulated with MATLAB/Simulink environment to estimate the maximum system power and investigate the effect of BOP component sizing on system performance and efficiency. The PEM fuel cell stack model was established by using a semi-empirical modeling. To maximize the net efficiency of fuel cell system, multi-variable optimization code was adopted. Using this method, the optimized operating values were obtained according to various system net power levels. The fuel cell model established was co-linked to AVL CRUISE, a vehicle simulation package. Through the vehicle simulation software, the fuel economy of fuel cell powered electric vehicle for two types of driving cycles was presented and compared. It is expected that this study can be effectively employed in the basic BOP component sizing and in establishing system operation map with respect to net power level of fuel cell system.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.4
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• pp.458-466
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• 2012

A Dual metal gate stack cylindrical/ surrounded gate MOSFET (DMGSA CGT/SGT MOSFET) has been proposed and an analytical model has been developed to examine the impact of this structure in suppressing short channel effects and in enhancing the device performance. It is demonstrated that incorporation of gate stack along with dual metal gate architecture results in improvement in short channel immunity. It is also examined that for DMGSA CGT/SGT the minimum surface potential in the channel reduces, resulting increase in electron velocity and thereby improving the carrier transport efficiency. Furthermore, the device has been analyzed at different bias point for both single material gate stack architecture (SMGSA) and dual material gate stack architecture (DMGSA) and found that DMGSA has superior characteristics as compared to SMGSA devices. The analytical results obtained from the proposed model agree well with the simulated results obtained from 3D ATLAS Device simulator.

• Progress in Superconductivity
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• v.9 no.1
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• pp.18-22
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• 2007

For interlayer tunneling spectroscopy using a small stack of $Bi_2Sr_2CaCu_2O_{8+x}$ (Bi-2212) intrinsic junctions in a high-bias range, large self-heating takes place due to the poor thermal conductivity of Bi-2212. In this study, we numerically estimate the self-heating around a Bi-2212 sample stack for I-V or dI/dV-V measurements. Our results show that the temperature discrepancy between the Bi-2212 sample stack and top Au electrodes due to bias-induced self-heating is small enough along the c-axis direction of Bi-2212. On the other hand, the lateral temperature discrepancy between the sample stack and the Bi-2212 on-chip thermometer stack can be as large as ${\sim}20\;K$ for the highest bias required to observe the pseudogap hump structure. We thus suggest a new in-situ ac thermometry, employing the Au current-bias electrode itself deposited on top of the sample stack as the resistive thermometer layer, which is supposed to allow safe temperature measurements for the interlayer tunneling spectroscopy.

• Journal of IKEEE
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• v.25 no.2
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• pp.280-284
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• 2021

In this paper, a new ESD protection circuit is proposed to improve the snapback characteristics. The proposed a new structure ESD protection circuit applying the conventional SCR structural change and stack structure. The electrical characteristics of the structure using penta-well and double trigger were analyzed, and the trigger voltage and holding voltage were improved by applying the stack structure. The electron current and total current flow were analyzed through the TCAD simulation. The characteristics of the latch-up immunity and excellent snapback characteristics were confirmed. The electrical characteristics of the proposed ESD protection circuit were analyzed through HBM modeling after forming a structure through TCAD simulator.

• The Journal of the Acoustical Society of Korea
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• v.28 no.1
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• pp.19-24
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• 2009

Investigations of the relation between the stack temperature profile of a standing wave thermoacoustic cooler and the cooling efficiency were performed. Based on the mathematical derivations using the Rott Equation, it was found that the temperature profile along the stack becomes nonlinear as the enthalpy flux passing through the stack increases. It was also found that such nonlinear temperature profiles lower the cooling efficiency. Simulations using a thermoacoustic simulation program called DELTAE showed that the nonlinear temperature profile occurs with a long stack and large cooling load.