• Journal of Hydrogen and New Energy
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• v.19 no.4
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• pp.313-321
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• 2008

Dynamics of the proton exchange membrane fuel cell is specially important when the system is frequently working on transient conditions. Even though the dynamics of proton exchange membrane fuel cell for residential power generation is less critical than that of PEMFC for transportation application, the system dynamics of PEMFC for RPG can be very important for daily start-up and stop. In particular, thermal management of the PEMFC for RPG is very important because the heat generation from electrochemical reaction is delivered to the home for hot water usages. Additionally, the thermal management is also very important for heat balance of the system and temperature control of the fuel cell. The objective of this study is to develop a dynamic system model for the study of PEMFC performance over various BOP options. Basic simulation results will be presented.

• Korean System Dynamics Review
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• v.9 no.2
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• pp.105-128
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• 2008

City of Gyeongju's referendum finally offered the long-waited low-level radioactive waste disposal site in November 2005. Gyeongju's positive decision was due to the various economic rewards and incentives the national government promised to the city. 300 billion won for an accepting bonus, the location of the headquarter building of the Korean Hydro and Nuclear Power Co., and the accelerator research center and 3.25 trillion won for supporting regional development program implementation. All of the above will affect the city's infrastructure and the citizens' economic and social lives. Population, land use, economic structure, SOC and quality of life will be affected. Some will be very positive, and some will be negative. This research project will see the future of the city and forecast the demographic, economic, physical and environmental changes of the city via computer simulation's system dynamics technique. This kind of simulation will help City of Gyeongju's what to prepare for the future. The population forecasting of the year 2046 will be 662,424 with the waste disposal site, and 327,274 without the waste disposal site in Gyeongju. The waste disposal site and regional supporting program will increase 184,246 Jobs more with 1,605 agriculture and fishery, 5,369 manufacturing shops and 27,577 shops. The population increase will bring 96,726 more houses constructed in the city. Land use will also be affected. More land will be developed. And road, water plant and waste water plant will be expanded as much. The city's financial structure will be expanded, due to the increased revenues from the waste disposal site, and property tax revenues from the middle-class employees of the company, and the high-powered scientists and technologists from the accelerator research center. All in all, the future of the city will be brighter after operating the nuclear waste disposal site inside the city.

• Korean System Dynamics Review
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• v.7 no.1
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• pp.119-146
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• 2006

City of Gyeongju's referendum finally offered the long-waited low-level radioactive waste disposal site in November 2005. Gyeongju's positive decision was due to the various economic rewards and incentives the national government promised to the city. 300 million won for an accepting bonus, 8.5 billion won, annual revenue fro the entry quantity of waste into the city's disposal site, the location of the headquarter building of the Korean Hydro and Nuclear Power Co., and the accelerator research center. All of the above will affect the city's infrastructure and the citizens' economic and cultural lives. Population, land use, economic structure, environment and quality of life will be affected. Some will be very positive, and some will be positive. This research project will see the future of the city and forecast the demographic, economic, physical and environmental changes of the city via computer simulation's system dynamics technique. This kind of simulation will help City of Gyeongju's what to prepare for the future. The population forecasting of the year 2026 will be 289,069 with the waste disposal site, and 279,131 without the waste disposal site in Gyeongju. The waste disposal site and the relocation of the company headquarters and location of the accelerator research center will attract 9,938 individuals more with 511 manufacturing shops and 1944 service jobs. The population increase will bring 3,550 more houses constructed in the city. Land use will also be affected. More land will be developed. However, mad, water plant and waste water plant will not be expanded as much. The city's financial structure will be expanded, due to the increased revenues from the waste disposal site, and property tax revenues from the middle-class employees of the company, and the high-powered scientists and technologists from the accelerator research center. All in an, the future of the city will be brighter after operating the nuclear waste disposal site inside the city.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.748-753
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• 2005

When the maneuver occurs, the performance of the standard Kalman filter has been degraded because mismatches between the modeled target dynamics and the actual target dynamics. To solve this problem, the unknown acceleration is determined by using the fuzzy logic based on genetic algorithm(GA) method. This algorithm is the method to estimate the increment of acceleration by a fuzzy system using th relation between maneuver filler residual and non-maneuvering one. To optimize this system, a GA is utilized. And then, the modified filter is corrected by the new update equation method which is a fuzzy system using the relation between the filter residual and its variation. To shows the feasibility of the suggested method with only one filter, the computer simulations system are provided, this method is compared with multiple model method.

• Journal of applied mathematics & informatics
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• v.40 no.5_6
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• pp.1199-1215
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• 2022

This article aims to study the dynamical behaviours of a two species model in which non-selective harvesting of a prey-predator system by using a reasonable catch-rate function instead of usual catch-per-unit-effort hypothesis is used. A system of two ordinary differential equations(ODE's) has been proposed and analyzed with the predator functional response to prey density is considered as Hassell-Varley type functional responses to study the dynamics of the system. Positivity and boundedness of the system are studied. We have discussed the existence of different equilibrium points and stability of the system at these equilibrium points. We also analysed the system undergoes a Hopf-bifurcation around interior equilibrium point for a various parametric values which has very significant ecological impacts in this work. Computer simulation are carried out to validate our analytical findings. The biological implications of analytical and numerical findings are discussed critically.

• Journal of Mechanical Science and Technology
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• v.14 no.12
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• pp.1328-1336
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• 2000

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.1
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• pp.1-9
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• 2004

In this paper, an efficient modeling method of Horizontal-Axis Wind Turbine(HAWT) system is proposed. This method Is based on representing a HAWT system as a multi-body system with several rigid bodies i.e. rotor blade, low/high speed shaft, gear system, md generator. Also, simulation software WINSIM is developed to evaluate performance of wind turbine system. Simulation results show that the proposed modeling method and simulation software are efficient and reliable.

• Journal of Mechanical Science and Technology
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• v.17 no.3
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• pp.350-356
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• 2003

In this study, a numerical analysis for the piston secondary dynamics of small refrigeration reciprocating compressors is performed. In general, the length of cylinder in this class of compressors is shortened to diminish the frictional losses of the piston-cylinder system. So, the contacting length between piston and cylinder wall is in variable with the rotating crank angle around the BDC of the reciprocating piston. In the problem formulation of the piston dynamics, the variation in bearing length of the piston and all corresponding forces and moments are considered in order to determine the piston trajectory, velocity and acceleration at each step. A Newton-Raphson procedure was employed in solving the secondary dynamic equations of the piston. The developed computer program can be used to calculate the entire piston trajectory and the lubrication characteristics as functions of crank angle under compressor running conditions. The results explored the effects of some design parameters and operating conditions on the stability of the piston, the oil leakage, and friction tosses.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.754-758
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• 1996

In this paper, a new method of position synchronizing control is proposed for multi-axes driving system. The proposed synchronizing control system is constituted with speed and synchronizing controller. The structure of synchronizing control system is varied by sign of synchronizing error. When a disturbance input becomes added to one axis, this axis becomes slave axis. The other axis is master axis. Therefore, master axis is not influenced by the disturbance. The speed controller of the first axis is designed by $H_{\infty}$ control theory. The speed controller of the second axis is designed by inverse dynamics of speed control system of the first axis. The speed control system designed with $H_{\infty}$ controller guarantees low sensitivity for the disturbance as well as robustness against model uncertainties. Especially, the synchronizing controller is designed to keep position error to minimize by controlling speed of slave axis. The effectiveness of the proposed method is successfully confirmed through several experiments.

• International Journal of Control, Automation, and Systems
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• v.4 no.6
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• pp.782-787
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• 2006

The role of Unmanned Aircraft Vehicles(UAVs) has been increasing significantly in both military and civilian operations. Many complex systems, such as UAVs, are difficult to model accurately because they exhibit nonlinearity and show variations with time. Therefore, the control system must address the issues of uncertainty, nonlinearity, and complexity. Hence, identification of the mathematical model is an important process in controller design. In this paper, attitude dynamics identification of UAV is investigated. Using the flight data, nonlinear state space model for attitude dynamics of UAV is derived and verified. Real time simulation results show that the model dynamics match experimental data.