• Journal of Mechanical Science and Technology
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• 제17권11호
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• pp.1784-1792
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• 2003

A hybrid method with supercompact multiwavelets is suggested as an efficient and practical method to compress CFD dataset. Supercompact multiwavelets provide various advantages such as compact support and orthogonality in CFD data compression. The compactness is a crucial condition for approximated representation of CFD data to avoid unnecessary interaction between remotely spaced data across various singularities such as shock and vortices. But the supercompact multiwavelet method has to fit the CFD grid size to a product of integer and power of two, m${\times}$2$^n$. To resolve this problem, the hybrid method with combination of 3, 2 and 1 dimensional version of wavelets is studied. With the hybrid method, any arbitrary size can be handled without any shrinkage or expansion of the original problem. The presented method allows high data compression ratio for fluid simulation data. Several numerical tests substantiate large data compression ratios for flow field simulation successfully.

• 한국자동차공학회논문집
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• 제7권7호
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• pp.136-148
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• 1999

Detailed mathematical models of hybrid drivertrain components are presented and numerical simulations are carried out to analyze the shift characteristics and to improve the driving comfortability when the hybrid drivetrain is applied at the vehicle . Theoretical results are compared with experimental ones from the dynamometer as same condition in order to prove the appropriateness of modeling . Adding the vehicle body modeling, included in the suspension and the engine mount, it is possible to predict the dynamic behavior and shift characteristics more actually when shifts are occurred by automated manual transmission(AMT). these additional results are also compared with the same simulation ones of internal combustion engined vehicle equipped conventional manual transmission. Hence, it can be expected that the hybrid vehicle with AMT has a good shift quality.

• Journal of Advanced Marine Engineering and Technology
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• 제40권5호
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• pp.429-436
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• 2016

Currently, many studies on green ships are under way. Fuel cell (FC) ships are of interest as future low-emission, fuel-efficient vessels. In this paper, a hybrid power management system for an FC ship was designed. The system consists of an FC, a battery, a unidirectional DC/DC converter, a bidirectional DC/DC converter, a filter, an inverter, and a propulsion component. To design the system, we analyze electric sources and converters, and create PLECS models of hybrid power management system. Then, we check the cold start sequence and perform a simulation to understand the characteristics of the hybrid power management system in an FC ship.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 PARALLEL CFD 2006
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• pp.27-34
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• 2006

In this paper, a recently proposed parallel hybrid particle-continuum (DSMC-NS) scheme employing 3D unstructured grid for solving steady-state gas flows involving continuum and rarefied regions is described [1]. Substitution of a density-based NS solver to a pressure-based one that greatly enhances the capability of the proposed hybrid scheme and several practical experiences of implementation learned from the development and verifications are highlighted. At the end, we present some simulation results of a realistic RCS nozzle plume, which is considered very challenging using either a continuum or particle solver alone, to demonstrate the capability of the proposed hybrid DSMC-NS method.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.243-245
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• 2005

Recently many research are going on in the field of application of Laser-Arc hybrid welding for superstructures such as shop-structures, transport vehicles etc. However, the study on heat distribution and welding residual stress of hybrid weld by numerical simulation leaves much to be desired. Therefore in this study an optimized welding condition and numerical simulation for hybrid welding by using previous numerical analysis which is used to calculate the heat source for hybrid welding has been analyzed.

• 대한전기학회논문지
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• 제45권2호
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• pp.230-234
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• 1996

A new trenched Hybrid Schottky INjection Field Effect Transistor (HSINFET) is proposed and verified by 2-D semiconductor device simulation. The feature of the proposed structure is that the hybrid Schottky injector is implemented at the trench sidewall and p-n junction injector at the upper sidewall and bottom of a trench. Two-dimensional simulation has been performed to compare the new HSINFET with the SINFET, conventional HSINFET and lateral insulated gate bipolar transistor(LIGBT). The numerical results shows that the current handling capability of the proposed HSINFET is significantly increased without sacrificing turn-off characteristics. The proposed HSINFET exhibits higher latch-up current density and much faster switching speed than the lateral IGBT. The forward voltage drop of the proposed HSINFET is 0.4 V lower than that of the conventional HSINFET and the turn-off time of the trenched HSINFET is much smaller than that of LIGBT.

• 전기학회논문지
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• 제61권7호
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• pp.1061-1068
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• 2012

In this paper, The Next Generation High Speed Railway inverter system using Hybrid Random Pulse Width Modulation (Hybrid RPWM) is proposed to reduce electromagnetic noise. To verify the validity of study, simulation results of the Next Generation High Speed Railway Inverter system using the proposed method was compared with the system using conventional method. A simulation program is developed using Matlab/Simulink. The results show that the voltage and current harmonics of the Next Generation High Speed Railway Inverter system using Hybrid RPWM significantly decrease and spread into wide band area.

• Journal of Information Processing Systems
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• 제15권2호
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• pp.422-432
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• 2019

A hybrid kernel function of support vector machine is proposed to improve the classification performance of power quality disturbances. The kernel function mathematical model of support vector machine directly affects the classification performance. Different types of kernel functions have different generalization ability and learning ability. The single kernel function cannot have better ability both in learning and generalization. To overcome this problem, we propose a hybrid kernel function that is composed of two single kernel functions to improve both the ability in generation and learning. In simulations, we respectively used the single and multiple power quality disturbances to test classification performance of support vector machine algorithm with the proposed hybrid kernel function. Compared with other support vector machine algorithms, the improved support vector machine algorithm has better performance for the classification of power quality signals with single and multiple disturbances.

• 소성∙가공
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• 제30권3호
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• pp.119-124
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• 2021

In this study, the hybrid and roller hemming processes of aluminum alloy sheets were compared using the finite element analysis. The aluminum alloy 6014-T4 sheet with a thickness of 1 mm was used for the hemming process. The mechanical properties of the aluminum sheet obtained through a uniaxial tensile test were used for the simulation. The finite element analysis of hybrid and roller hemming was performed using a commercial software (ABAQUS) by the use of the mechanical properties. The finite element simulation results showed that the hybrid hemming holds an advantage over the roller hemming in terms of the dimensional accuracy

• 한국자동차공학회논문집
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• 제22권5호
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• pp.102-107
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• 2014

Because of high oil prices and emission gas problems, many governments tighten regulation of fuel economy and emission gas. For Passenger car, there are many researches for plug-in hybrid electric vehicles and they are being manufactured. On the other hand, there are few researches for plug-in hybrid electric bus that is heavy commercial vehicle. In this study, analysis of fuel economy for series plug-in hybrid electric bus according to engine operation strategy based on simulation is conducted. Forward simulator is developed using Autonomie. Engine operation strategies consist on constant engine operation strategy and engine on/off operation strategy. Considering the engine operation strategy, results of vehicle speed, engine operating points and fuel economy are obtained and analyzed. As a result, engine on/off operation strategy has more advantage than constant engine operation strategy in terms of fuel economy.