• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.53 no.10
• /
• pp.678-689
• /
• 2004

The major concern of networked control system is network uncertainties such as time delay and data loss. Because these uncertainties may degrade the performance of networked control system and destabilize the entire system. Therefore, the performance and the stability variation of networked control system due to network uncertainties must be considered first in designing networked control system. In particular, the stability analysis of networked control system is most important issue since time delay and data loss can make the overall systems unstable. In this paper, we present a new stability analysis method of networked control system with time delay and data loss, which is impossible in previous works. The proposed method can determine maximum time delay and allowable transmission rate that preserve stability performance of networked control system. The results of the simulation validate effectiveness of our stability analysis method.

• Journal of Korean Public Health Nursing
• /
• v.17 no.1
• /
• pp.26-34
• /
• 2003

The purpose of this study was to analyze the activities of Community Health Nurse Practitionses using the Community Health Post Information System(CHPIS). The information system that have been introduced in 1994 and used by 400 Community Health Posts(CHPs) since 1997, which is about $20\%$ of the total CHPs nationwide. Twenty-five CHPs from two provinces participated in the analysis. Seventy-two percent of the CHPs among the participating CHPs started using the system since 1996. The degree of utilization of the information system was classified into three groups (i. e., high. medium, and low). The results revealed that only $48\%$ utilized the system with high level. The areas of analysis of the information system included characteristics of community residents, environmental attributes, and job analysis of Community Health Nurse Practitioners(CHNPs). The study results indicated that primary health care and drug demand and supply system showed the highest level of satisfaction in utilizing the information system by CHNPs.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.8
• /
• pp.1296-1302
• /
• 2008

This paper deals with modeling and dynamic characteristic analysis of a large-powered LNG electric ship propulsion system. Basically, we perform to verify the adequacy of system modeling on the sea going mode and LNG unloading mode based on load flow analysis. And then, we observe the dynamic characteristic of system to perform motor starting analysis and transient stability analysis. Particularly, this paper examine analysis results in comparison with the IEEE standard 141 and the class rule. Hence, this paper has evaluated stability of the electric ship propulsion system at static and dynamic conditions.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.5 no.3
• /
• pp.19-28
• /
• 2009

Computer system performance has always had the possibility of affecting business profitability, but with the advent of the World Wide Web where customers interact directly with Web servers, response time can have a direct and dramatic impact on business revenue. This paper is written in the operation environment and system analysis of HTS(Home Trading System) running K Securities. This paper also shows the method for performance improvement through investigation and analysis for the overall systems resources whether HTS has an appropriate performance or not. Performance analysis includes specially CPU analysis, Memory analysis, Disk Input/Output analysis and application analysis. Besides providing more detailed server specification for expansion from now on, system performance can be maintained with effect in the future. Through this study it is possible to manage the performance of HTS more easily and to solve problems such as a bottleneck more quickly.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.648-651
• /
• 2004

Biped robot has better mobility than other mobile robot, but it is hard to maintain balance during walking. In order to maintain balance, stability analysis is a key point for a biped robot. The zero moment point analysis has been used most in stability analysis. In this paper, we propose different method of stability analysis using wrench system. It is possible to generate a wrench system by applying a force along an axis in space and simultaneously applying a moment about the same axis. Wrench system is equivalent to a force and moment applied along the same axis. We compare the result of wrench system analysis with that of zero moment analysis in biped robot stability using simulation program.

• Korean Journal of Computational Design and Engineering
• /
• v.5 no.2
• /
• pp.184-195
• /
• 2000

MDO (Multidisciplinary Design Optimization) methodology is an emerging new technology to solve a complicate structural analysis and design problem with a large number of design variables and constraints. In this paper MDO methodology is adopted through the use of computer aided systems such as Geometric Solid Modeller, Mesh Generator, CAD system and CAE system. And this paper introduces MDO methodology as a new method for structural analysis and design through the application to the structural design of flap drive system. In a MDO methodology application to the structural design of flap drive system, kinetodynamic analysis is done using a simple aerodynamic analysis model for the air flow over the flap surface instead of difficult aerodynamic analysis. Simultaneously the structural static analysis is done to obtain the optimum structural condition. And the structural buckling analysis for push pull rod is also done to confirm the optimum structural condition (optimum cross section shape of push pull rod).

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1994.04a
• /
• pp.596-605
• /
• 1994

An efficient measurement and evaluation system for hand tool tasks will provide a practical solution to the problem of designing and evaluating manual tool tasks in the workplace. Few studies on the biomechanical analysis of hand postures and tool handling tasks exist because of the lack of appropriate measurement techniques for hand force. A measurement system for the finger forces and joint angles for analysis of manual tool handling tasks was developed in this study. The measurement system consists of a force sensing glove made from twelve Force Sensitive Resistors and an angle-measuring glove (Cyberglove$\^$TM/, Virtual technologies) with eighteen joint angle sensors. A biomechanical model of the hand using the data from the measurement system was also developed. Systems of computerized procedures were implemented integrating the hand posture measurement system, biomechanical analysis system, and the task analysis system for manual tool handling tasks. The measurement system was useful in providing the hand force data needed for an existing task analysis system used in CTD risk evaluation. It is expected that the hand posture measurement developed in this study will provide an, efficient and cost-effective solution to task analysis of manual tool handling tasks. These tasks are becoming increasingly important areas of occupational health and safety of the country.

• Journal of Power System Engineering
• /
• v.18 no.1
• /
• pp.63-68
• /
• 2014

The numerical analysis of fluid flow in the tube cleaning system is examined. The working flow used in this study is seawater, and the temperature change is not considered as the temperature change of seawater in the tube cleaning system is negligible. Also, the analysis is performed under the assumption of steady state. The screens of complicated morphologies are simplified for the analysis, and only one fourth of the tube cleaning system is modeled as the system has a symmetrical shape. The velocity inlet boundary condition is employed for the seawater inlet, whereas the outflow boundary condition is employed for two seawater outlets. In applying the outflow boundary condition for the system with more than two outlets, the flow rate can be arbitrarily assigned. In the analysis, the finite-volume method based numerical analysis tool, the pressure based solver, the standard k-$\varepsilon$ model are utilized, and the under relaxation factor is modified appropriately. From the analysis, the distribution of velocity vectors, pressure and path lines are obtained, and the physical characteristics of fluid flow in the tube cleaning system is well-examined.

• KIEE International Transactions on Power Engineering
• /
• v.3A no.2
• /
• pp.93-99
• /
• 2003

This paper deals with the development and testing of a large-scale, realtime digital power system simulator for the Korean Electric Power Corporation. The KEPS Simulation Center is located at KEPCO's research center (KEPRI) in Taejon, South Korea and has been operated since September 2001. The KEPS Simulation Center includes a wide range of off line power system simulation and analysis tools, as well as an advanced realtime digital simulator for the study of large scale AC and DC system performance. Because the application scope of the KEPS realtime simulator is broad and because the network models being considered are significantly larger and more complex than in traditional realtime simulator applications, many developments and tests have been required during the course of the project. In this paper, the authors describe some of these developments and present results from various benchmark tests that have been performed.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.1
• /
• pp.98-105
• /
• 2010

Squeal, a kind of self-excited vibration, is generated by the friction between the disc and the friction materials. It occurs at the ending stage of the braking process, and radiates and audible frequency range of 1 kHz to 10 kHz. Squeal is generated from unstability because of the coupling between the translation and rotation of the system. This instability is caused by the follower force and follower force is normal component of the friction force. In this paper modal analysis of wheel brake system was performed in order to predict the squeal phenomenon. It was shown that the prediction of system instability is possible by FEM. A finite element model of that brake system was made. Some parts of a real brake was selected and modeled. Modal analysis method performs analyses of each brake system component. Experimental modal analysis was performed for each brake components and experimental results were compared with analytical results from FEM. To predict the dynamic unstability of a whole system, the complex eigenvalue analysis for assembly modeling of components confirmed by modal analysis is performed. The finite element models of the disk brake assembly have been constructed, and the squeal noise problems have been solved by complex eigenvalue analysis. The complex eigenvalue analysis results compared with real train test.