• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.281-284
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• 2014

Unlike ordinary vehicle chassis frame, chassis frame of military vehicle is long and that is operated in harsh driving environment in middle of war. Thus, because large dynamic loads is acting on the frame, it is important to secure the durability of the frame based on the structural dynamic characteristic analysis. The purpose of the study is that the chassis frame is optimized to secure durability of the chassis frame of the military vehicle according to the structural dynamic characteristic analysis. Also, structure optimization are performed using parametric optimization and topology optimization methods.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.341-346
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• 2006

This paper provides the resuIts on the evaluation of dynamic characteristics of the optimized shells. Five fundamental technologies such as computer-aided geometric design, automatic mesh generation, shell finite element, design sensitivity analysis and shell optimization process, are used for shell optimization maximizing the fundamental natural frequency. A dome shell is adopted for the shell shape optimization and the dynamic characteristic of the optimized shell such as the variation of natural frequencies is then investigated. From the investigation, more constraint functions related to shell natural frequencies is necessarily required to effectively control dynamic characteristics of the optimized shells.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.82-89
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• 2001

This paper proposes several methods to analyze dynamic and static characteristics of HVDC inverter system. The characteristic analysis is essential of the controller and filter design of the HVDC inverter system. Dynamic characteristic can be analyzed with EMTP simulation and static characteristic can be obtained by solving newly proposed load flow equation which includes the filter and load characteristic. New simple per-phase-equivalent circuit is also proposed. In this circuit, HVDC inverter is considered as a current source depending on the on-off status of switch. Dynamic and static characteristic can be analyzed by the proposed per-phase-equivalent circuit. For the optimal filter design, various performance criteria are proposed. The performance index, based on the per-phase-equivalent circuit, is calculated. Voltage harmonics and filter power loss are selected as criteria. Optimization procedure is explained to find optimal passive filter parameters.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.12
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• pp.61-69
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• 1997

This paper proposes a new method for improving the performances of the neural network for optimization using a hyubrid of gradient descent method and dynamic tunneling system. The update rule of gradient descent method, which has the fast convergence characteristic, is applied for high-speed optimization. The update rule of dynamic tunneling system, which is the deterministic method with a tunneling phenomenon, is applied for global optimization. Having converged to the for escaping the local minima by applying the dynamic tunneling system. The proposed method has been applied to the travelling salesman problems and the optimal task partition problems to evaluate to that of hopfield model using the update rule of gradient descent method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.403-408
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• 2007

According as diesel automobile are produced, reduce noise and vibration that is occurred by characteristic of diesel engine, and need engine room layout optimization and research for light weight of parts. Balance Shaft Module is module parts for vehicles engine to improve performance and efficiency of engine and reduce noise and vibration. These days, an oil pump integrated balance shaft module and an oil sump integrated balance shaft module is on the rising for optimizing of engine room. In this study, produced prototype of oil pump integrated type balance shaft module, and achieved dynamic characteristic test about experimental modal analysis and noise/vibration of balance shaft module.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.365-367
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• 2002

A parallelized topology optimization is applied to the design of a DVD-pickup bobbin, for which the design objective is to maximize the fundamental frequency within a given mass limit. Unlike the existing serial topology optimization, the present method can deal with a large number of design variables, and thus can yield practical and realistic results. The structural member-sizing filter is also employed to control the topological complexity of the optimized bobbin structure.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.89-96
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• 1999

This paper presents the optimization design technique on the joint stiffness and section characteristic factors of chassis frame, by using beam and spring elements in a given design package. Two correction methods are used for the optimization design of chassis frame. First is the equivalent inertia of moment method in relation to the section characteristic factors of joint zones, which are thickness , width and height of frame channel section. Second is the rotational spring element with joint stiffness of joint zones. The CAE example shows that the relationship of section characteristic factors and joint stiffness can effectively be used in designing chassis frame. In this point, if static and dynamic targets are given, the joint-zone and section characteristic factors of chassis frame intended may be designed and defined by using beam and rotational spring elements.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.6
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• pp.591-600
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• 2015

The efficiency of a powertrain system of hybrid vehicle is highly dependent on the design and control of the hybrid powertrain system. In other words, the optimal design of the powertrain systems is coupled with optimal control of the powertrain system. Therefore, the solution of an optimal design problem for hybrid vehicles is computationally and timely very expensive. For example, dynamic programming, which is a recursive optimization method, is usually used to evaluate the best fuel economy of certain hybrid vehicle design, and, thus, the evaluation takes tens of minutes to several hours. This research aims to accelerate the speed of efficiency evaluation of hybrid vehicles. We suggest a mathematical treat and a methodological treat to reduce the computational load. The mathematical treat is that the dynamics of system is discretized with sparse sampling time without loss of energy balance. The methodological treat is that the efficiency of the hybrid vehicle is inferred by characteristic loss evaluation that is computationally inexpensive. With the suggested methodology, evaluating a design candidate of hybrid powertrain system is taken few minutes, which was taken several hours when dynamic programming is used.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.389-396
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• 2002

In this study, the dynamic absorbing system for gas operated gun has been investigated. For this purpose, firstly. mathematical model of gas-operated shoulder-fired gun has been constructed. Through a series of experimental works using the devised test setup, the characteristic behavior of mathematical model was compared to the test results. In order to design the dynamic absorbing system, parameter optimization process has been performed based on the simplified isolation system under constraints of moving displacement and transmitted force. In order to implement the more efficient dynamic absorbing system, the characteristic performance of stroke-dependent variable damping system has been analyzed with some opening area curves. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation and experiment using the previous test apparatus.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.345-350
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• 2001

Dynamic behavior of high speed train is very important because the high speed train should be safe and satisfied with the ride comfort. An eddy current brake system is mounted on trailer bogie and wheelset. The eddy current braking force longitudinally exerts on the articulated trailer bogie and the attraction force vertically exerts on the wheelset. Because a frame of eddy current brake system is flexible, these forces generate the vertical vibration at middle point of the frame. Also, the vibration change the vertical clearance between an electromagnet and top of rail which affect the magnitude of braking and attracting forces. Therefore, the dynamic behavior of the eddy current braking system must be predicted for design the dynamic characteristic of its mounting system when normally operate on rail which have irregularity. Vampire program is used for prediction of the dynamic behavior of an eddy current braking system. Five design variables and five performance index are considered for optimization through D-optimal experimental design in this paper. Also model center is used to search the optimal point for sum of performance index with variational matric method.