• Journal of Aerospace System Engineering
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• v.15 no.4
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• pp.7-10
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• 2021

Including 425 Program, which is Korean military surveillance and reconnaissance satellite, there were mostly civil-driven space programs in Korea. However, there are increasing numbers of military demand-driven space program in nowadays. Furthermore, it is positive effects on launch vehicle development in Korea that the termination of Korea-U.S. missile guideline. In this paper, it emphasizes the needs of system engineering(SE) management method which meets both defense system's characteristics and space's characteristics. These characteristics are such as non-fixable after the launch, the security issue in defense system. And it also introduces SE tool, methodology and its philosophy. There are several functions that data management, issue management, risk management, and technical requirement management. Also describing its implications and direction of improvement.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.4
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• pp.163-172
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• 2004

Nowadays, to analyze the dynamic characteristics of the automotive driving system, the computer simulation linked up with VR(Virtual Reality) technology is treated as the useful method with the improvement of computing ability. In this paper, the VR simulation system has been developed to investigate the driving characteristics of the ASV(Advanced Safety Vehicle) equipped with an ACC(Adaptive Cruise Control) system. For the purpose, VR environment which generates 3D graphic and sound information of the vehicle, the road, the facilities, and the terrain has been organized for the driving reality. Mathematical models of vehicle dynamic analysis including the ACC model have been constructed for computer simulation. The ACC modulates the throttle and brake functions to regulate the vehicle speed so that vehicles could keep proper spacing. Also, the real-time simulation algorithm synchronizes vehicle dynamic simulation with the graphic rendering. With the developed VR simulation system, simple scenarios are applied to analyze the dynamic characteristics. It is shown that the VR simulation system could be useful to evaluate the adaptive cruise controlled vehicle on various driving conditions.

• Industrial Engineering and Management Systems
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• v.9 no.3
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• pp.215-226
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• 2010

Since product design strongly depends on the experience and ability of the designers, and a long lead time is required for the product design stage, introducing a support system related to this experience and ability is an effective technique to reduce the lead time. In this paper, an information system is developed to support the development of engineering mechanisms with the evaluation of the assembly process on the basis of the abstract functions required for new products. The developed system is based on a database system involving the following data structure: (1) a hierarchical structure related to information about the product functions, (2) the relationship between the parts and engineering functions and/or mechanisms of products, and (3) the relationship between the parts and manufacturing characteristics. The system stores the relationships between the product functions, structure of parts, and assembly characteristics. This information can then be interactively retrieved using the data structure described in (1), (2), and (3). A procedure for designing new products is proposed that involves using the information about existing products. This paper presents the characteristics of the proposed procedure and the developed information system. In addition, a case study of the redesign of a simple structured robot by using the proposed procedure is discussed.

• Safety and Health at Work
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• v.8 no.2
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• pp.189-197
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• 2017

Background: Despite the recent efforts to prevent industrial accidents in the Republic of Korea, the industrial accident rate has not improved much. Industrial safety policies and safety management are also known to be inefficient. This study focused on dynamic characteristics of industrial safety systems and their effects on safety performance in the Republic of Korea. Such dynamic characteristics are particularly important for restructuring of the industrial safety system. Methods: The effects of damping and elastic characteristics of the industrial safety system model on safety performance were examined and feedback control performance was explained in view of cost and benefit. The implications on safety policies of restructuring the industrial safety system were also explored. Results: A strong correlation between the safety budget and the industrial accident rate enabled modeling of an industrial safety system with these variables as the input and the output, respectively. A more effective and efficient industrial safety system could be realized by having weaker elastic characteristics and stronger damping characteristics in it. A substantial decrease in total social cost is expected as the industrial safety system is restructured accordingly. Conclusion: A simple feedback control with proportional-integral action is effective in prevention of industrial accidents. Securing a lower level of elastic industrial accident-driving energy appears to have dominant effects on the control performance compared with the damping effort to dissipate such energy. More attention needs to be directed towards physical and social feedbacks that have prolonged cumulative effects. Suggestions for further improvement of the safety system including physical and social feedbacks are also made.

• Journal of ILASS-Korea
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• v.9 no.2
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• pp.9-17
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• 2004

The performance characteristics of lean burn system in gasoline engine are mainly affected by the air-fuel mixture in cylinder, gas exchange process of manifold system, exhaust emission of engine, and the electronic engine control system. In order to obtain the effect of performance factors on the optimum conditions of lean burn engine, this study deal with the behavior of mixture formation, gas flow characteristics of air, flow and evaporation analysis of spray droplet in cylinder, vaporization and burning characteristics of lean mixture in the engine, and the control performance of electronic engine control system. The optimum flow conditions were investigated with the swirl and tumble flows in the combustion chamber with swirl control valve. The performance characteristics and optimum condition of flow field in intake system were analyzed by the investigation of inlet flow of air and combustion stabilization on cylinder.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.4
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• pp.57-62
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• 2003

A fundamental structural design consideration for a vehicle system is the overall vibration characteristics in bending and torsion. Vibration characteristics of such vehicle system are mainly influenced by the static and dynamic stiffness of the vehicle body structure and also by the material and physical properties of the components attached to the vehicle body structure. In this paper, modeling techniques for the vehicle components are presented and the flexibility and mass effects of the components for the vibration characteristics of the vehicle are investigated. The $1^{st}$ torsional frequency is increased by attaching windshields to the B.I.W. (body-in-white), but the $1^{st}$ bending frequency is decreased by the mass effect. And also, the natural frequencies of the vehicle are large decreased by attaching bumpers, seats, doors, trunk-lid etc. But, suspension system rarely affects the natural frequencies of the vehicle. The study shows thai the dynamic characteristics of the vehicle system can be effectively predicted in the initial design stage.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1370-1376
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• 2015

Generally, an autotransformer(AT) feeding system consists of double tracks, up and down, with the trolley wire and feeder wire of the up and down tracks connected in the sectioning post(SP). Consequently, load current or fault current flows on two tracks based on catenary impedance characteristics, making it difficult to estimate catenary impedance accurately. This paper presents a technique for the estimation of catenary impedance using boosting current compensation based on the current division characteristics of an AT feeding system to improve the operation performance of impedance relay. To verify the technique, we model an AT feeding system through a power analysis program (PSCAD/EMTDC) and simulate various operation and fault conditions. Through the simulation, we confirmed that the proposed technique has estimated catenary impedance with a similar degree of accuracy to the actual catenary impedance

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.1
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• pp.109-117
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• 2004

The objective of this study is to investigate the effect of the spray characteristics on the etching characteristics for the optimization of etching process in the micro fabrication industry. The etching characteristics such as etching rate and etching factor were investigated under different etching conditions. To compare with the etching characteristic, the spray characteristics such as droplet size and velocity were measured by PDA system. The etching rate was increased in case of high spray pressure and in the region of spray center. The etching factor was increased with decrease in the distance from nozzle tip and increase in the etchant temperature. It was found that the spray characteristics were correlated with the etching characteristics.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.458_459
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• 2009

This paper analyzes the dynamic characteristics for doubly-fed induction generator(DFIG) in wind turbine system. This paper presents a modeling and simulation of a grid-connected wind turbine generation system for dynamics analysis on MATLAB/Simulink, and analyzes the responses DFIG wind turbine system for stiffness of linked system. Simulation results show the variations of generator's active/reactive output, terminal voltage, fault current, etc.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.11 no.18
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• pp.35-39
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• 1988

In general, the characteristics of components which consist of multi component system can not be the same. This paper proposes a maintenance model of multi-component system according to the characteristics of each component. In this paper multi-component system is divided into three components-critical component, major component and minor component, respectively. Then we determine the optimal age replacement time of the system which minimizes total maintenance cost. Numerical examples are shown to illustrate the result.