• Journal of Korean Institute of Industrial Engineers
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• v.30 no.1
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• pp.50-57
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• 2004

The aim of this study is to collect driver's psychophysiological signal under various road condition and to select and quantify psychophysiological variables for diagnosis of road-driver compatibility. A 4x4 vehicle with measuring devices was developed to collect driver's psychophysiological signal and collected driver's psychophysiological signal under various road conditions. The collected data were analyzed by the temporal pattern of signal overtime. Thirteen bio-signals with consistent pattern were selected and quantified in terms of slope and amplitude of the signal. These quantified values could be used as a part of tool to diagnose the road-driver compatibility.

• Journal of Power Electronics
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• v.16 no.3
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• pp.994-1003
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• 2016

Two major obstacles in the utilization of electrical vehicles are their price and range. The collaboration of direct torque control (DTC) with induction motor (IM) is preferred for its low cost, easy implementation, and parameter independency. However, in terms of edges, the method has drawbacks, such as variable switching frequency and undesired current harmonic distortion. These drawbacks result in acoustic noise, reduced efficiency, and electromagnetic interference. A feed-forward approach for stator-flux-oriented DTC with space vector pulse-width modulation is presented in in this paper. The outcome of the proposed method is low current harmonic distortion with fixed switching frequency while preserving the torque performance and simple application feature of basic DTC. The method is applicable to existing and forthcoming IM drive systems via software adaptation. The validity of the proposed method is confirmed by simulation and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.7
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• pp.468-474
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• 2000

This paper presents an investigation of the parameter modeling on the basis of Finite Element (FE) analysis in which the variable frequency characteristic in field weakening is considered in Interior Permanent Magnet Synchronous Motors (IPMSM). The parameters of IPMSM have nonlinear characteristics not only in accordance with the load variation but also with the current phase angle of a system fed inverter. From the results of FE analysis, the performances of torque and speed-power are simulated and the validity of the proposed FE analysis is compared with experimental results.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.146-148
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• 1998

For the shape design of electromagnetic devices using the FEM, the choice of design parameters influence to the success of the optimization process. If the design parameter distribution has a one to one corespondence with finite element model, we can encounter not only serious accuracy problem but also obtain a zigzag shape along the interface. The nodes between those design parameters can be parameterized by interpolating using one among many interpolation methods. The conventional parameterization of design parameters has a limit of application for shape, because design parameters and movable nodes are linearly intepolated. In this paper, using the B-spline curve that use to present any interfaces in computer graphics, the curvilinear parameterization between design parameters and node points is compared with the linear parameterization.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2455-2457
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• 2000

In this paper, it is proposed a neural adaptve control algorithm for boiler-turbine system. Control inputs are constructed using RBF Neural networks and variable structure inputs are added to improve the robustness. This proposed algorithm does not need the information about parameters and can assure the robustness under the output disturbance and parameter perturbations. The results of computer simulations is presented to verify the efficiency of the proposed algorithm.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.218-220
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• 2005

This paper shows the analysis of the inductive power transfer system in conjunction with series resonant converter operating variable high frequency. Of particular interest is the sensitivity of the complete system to variations in operational frequency and parameters. In inductive power transfer system, electrical power is transferred from a prima교 winding in the form of a coil or track, to one or more isolated pick-up coils that may relative to the primary. The ability to transmit power without contact enables high reliability and easy maintenance that allows inductive power transfer system to be implemented in hostile environments. This technology has found application in many fields such as electric vehicles, PRT(Personal Rapid Transit) etc. The coupling between the primary and secondary is then presented to include the effects of parameter and operational frequency variation.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.784-786
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• 1995

Variable Structure Control(VSC) scheme with sliding mode is widely used to keep a control system insensitive to parameter variations and disturbances. However, the conventional sliding mode control has the undesired phenomenon of chattering which may become a serious problem. Also the restriction of the sliding mode regime cannot guarantee the insensitivity throughout an entire response. In this paper, the sliding surfaces, which are composed of three-line segments, are used to remove the reaching phase. Also, the concept of fuzzy logic is incorporated with the sliding mode control in order to control the unknown or partially known systems effectively. The proposed method is applied to a Double-Sided MM Type LDM to show its usefulness.

• Ocean Systems Engineering
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• v.5 no.2
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• pp.91-107
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• 2015

Ship hull optimization is categorized as a bound, multi variable, multi objective problem with nonlinear constraints. In such analysis, where the objective function representing the performance of the ship generally requires computationally involved hydrodynamic interaction evaluation methods, the objective functions are not smooth. Hence, the evolutionary techniques to attain the optimum hull forms is considered as the most practical strategy. In this study, a parametric ship hull form represented by B-Spline curves is optimized for multiple performance criteria using Genetic Algorithm. The methodology applied to automate the hull form generation, selection of optimization solvers and hydrodynamic parameter calculation for objective function and constraint definition are discussed here.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1194-1201
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• 1996

For the case of creep-fatigue interaction, the damage zone developed in front of the growing crack-tip during creep regime is important because it can affect the damage mechanism to be occured by the following fatigue load. These are studied in theis paper through proper consideration of the cavitiy-size dependent sintering stress which is approximated by polynomials. It is shown that the inclination of reversed damage zone size with respect to the applied load parameter can be explained by considering realistic sintering stress distribution. However, the resultant stress field has $r^{1/2+\theta}$ singularity, regardliss of the profile of variable sintering stress, which is the same to that case solved for constant sintering stress.

• International Journal of Reliability and Applications
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• v.14 no.1
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• pp.41-54
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• 2013

In this paper, cost analysis is conducted using inter-failure interval under renewable warranty subject to imperfect repair for multi-component system. One way to model the imperfect repair is to use the quasi-renewal process (Wang and Pham 1996). Two alternative quasi-renewal processes were suggested by Park and Pham (2010) using quasi-renewal process; first is an altered quasi-renewal process with random variable parameter and second is a mixed quasi-renewal process considering replacement service and repair service, simultaneously. In this study, we use the altered and mixed quasi-renewal processes and develop the warranty cost model to obtain the expected value of warranty cost and to help company make important decisions regarding the warranty policy. Numerical examples are used to demonstrate the applicability of the methodology derived in the paper.