• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.2
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• pp.121-128
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• 2014

This study aims to develop a simulation bed for the mechanical balance of plants of high temperature fuel cells such as molten carbonate fuel cells. For using fuel cells in transportation, the optimization of the balance of plants should be considered. In this study, the dynamic model of a molten carbonate fuel cell and the model's responses to inlet gas composition, pressure, flow rate, and stack temperature were analyzed. On/off simulation was performed for testing the dynamic model's feasibility. The simulation results are in reasonable agreement with the experimental results from published literatures.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.54-62
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• 2013

This paper proposes a high-efficiency DC-DC converter with improved dynamic response characteristics for modular photovoltaic power conversion. High power efficiency is achieved by reducing switching power losses of the DC-DC converter. The voltage stress of power switches is reduced at primary side. Zero-current switching of output diodes is achieved at secondary side. A modified proportional and integral controller is suggested to improve the dynamic responses of the DC-DC converter. The performance of the proposed converter is verified based on a 200 [W] modular power conversion system including the grid-tied DC-AC inverter. The proposed DC-DC converter achieves the efficiency of 97.9 % at 60 [V] input voltage for a 200 [W] output power. The overall system including DC-DC converter and DC-AC inverter achieves the efficiency of 93.0 % when 200 [W] power is supplied into the grid.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2488-2491
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• 2000

A Neural network is possible to nonlinear function mapping and parallel processing. Therefore It has been developing for a Diagnosis system of nuclear plower plant. In general Neural Networks is a static mapping but Dynamic Neural Network(DNN) is dynamic mapping. When a fault occur in system, a state of system is changed with transient state. Because of a previous state signal is considered as a information. DNN is better suited for diagnosis systems than static neural network. But a DNN has many weights, so a real time implementation of diagnosis system is in need of a rapid network architecture. This paper presents a algorithm for RCP monitoring Alarm diagnosis system using Self Dynamic Neural Network(SDNN). SDNN has considerably fewer weights than a general DNN. Since there is no interlink among the hidden layer. The effectiveness of Alarm diagnosis system using the proposed algorithm is demonstrated by applying to RCP monitoring in Nuclear power plant.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.303-310
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• 2020

Estimating the accurate internal state of lithium ion batteries to increase their safety and efficiency is crucial. Various algorithms are used to estimate the internal state of a lithium ion battery, such as the extended Kalman filter and sliding mode observer. A state-space model is essential in using algorithms to estimate the internal state of a battery. Two principal methods are used to express the state-space model, namely, continuous time and discrete time. In this work, the extended Kalman filter is employed to estimate the internal state of a battery. Moreover, this work presents and analyzes the estimation performance of algorithms consisting of a continuous time state-space model and a discrete time state-space model through static and dynamic profiles.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.3
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• pp.70-78
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• 1989

In the control of the robot system using the variable structure control(VSC) method, up to these days the advantage of the VSC method has not been applied effectively because the parameters are selected arbitrarily by the existence condition of sliding mode without a precise analysis about the VSC parameters. This paper reveals the relation between dynamic constraints and the VSC parameters of robot system, and analyzes the effect on the trajectory of the joint angle and the hand when the analytical result of the relation is applied to the robot system control. The result of the analysis in this paper is applied effectively to the path tracking control and the trajectory planning using the VSC method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1535-1540
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• 2013

We propose a finite element modeling method considering the ball bearing contact mechanism, and the developed method was verified through experimental and analytical results of inner and outer race-type rotor systems. A comparison of the proposed method with conventional method reveals that there is little difference in the results of the inner race-type rotor system, but there are considerable differences in the results of the outer race-type rotor system such that predictions of greater accuracy can be made. Therefore, the proposed method can be used for accurately predicting the dynamic characteristics of an outer race-type rotary machine.

• Wind and Structures
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• v.18 no.4
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• pp.391-422
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• 2014

The high frequency force balance (HFFB) technique provides convenient measurements of integrated forces on rigid building models in terms of base bending moments and torque and/or base shear forces. These base moments or forces are then used to approximately estimate the generalized forces of building fundamental modes with mode shape corrections. This paper presents an analysis framework for coupled dynamic response of tall buildings with HFFB technique. The empirical mode shape corrections for generalized forces with coupled mode shapes are validated using measurements of synchronous pressures on a square building surface from a wind tunnel. An alternative approach for estimating the mean and background response components directly using HFFB measurements without mode shape corrections is introduced with a discussion on higher mode contributions. The uncertainty in the mode shape corrections and its influence on predicted responses of buildings with both uncoupled and coupled modal shapes are examined. Furthermore, this paper presents a comparison of aerodynamic base moment spectra with available data sets for various tall building configurations. Finally, e-technology aspects in conjunction with HFFB technique such as web-based on-line analysis framework for buildings with uncoupled mode shapes used in NALD (NatHaz Aerodynamic Loads Database) is discussed, which facilitates the use of HFFB data for preliminary design stages of tall buildings subject to wind loads.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.10
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• pp.1029-1037
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• 2015

Recently, the importance of rotordynamic stability has been increased because of the tendency to employ ultra-high speeds in rotating machinery. In particular, the dynamic characteristics of gas bearings for high-speed rotating machinery need to be identified at various excitation frequencies to predict the rotor's behavior. In this study, we perform dynamic loading tests for gas-foil bearings (GFBs) to determine the bump foil structure and an air-film combined bump-foil structure for varying excitation frequencies. We calculate the dynamic characteristics from the measured force and displacement data. The air film is generated by a pressurized air supply. Based on the results, the stiffness coefficients of the bump structure and the air-film combined bump structure increased, while the damping coefficients decreased at increasing excitation frequencies. Further, the stiffness and damping coefficients of the air-film combined structure show lower values than those of the bump structure. Consequently, we identify the frequency-dependent dynamic characteristics of the bump structure and the effect of gas film on the dynamic characteristics of GFBs. Furthermore, to reveal the effectiveness of the proposed method, we perform experiments and discuss two methods of extracting the dynamic characteristics from the measured data.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.11
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• pp.31-35
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• 1992

This paper presents a decentralized adaptive controller design for a robot manipulator to track the given desired trajectory in the joint space. The controller is of distributed structure and does not require the complex manipulator dynamic model, thereby it is computationally very efficient. Each joint is independently controlled by a PID feedback part and a velocity-acceleration feedforward part. Simulation results for a two-link direct drive manipulator conform that the proposed decentralized scheme is feasible.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.703-705
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• 1998

In this paper, we have suggested the method of genetic algorithm to solve the trajectory optimization. The given nonlinear method is so complex and modeling is not easy. Also, we have suggested the nonlinear programming combined with genetic algorithm. The proposed algorithm gives simple and time-reducing method in solving nonlinear dynamic systems.