• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.242-248
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• 2002

It is important to develop new effective technologies to increase the interruption capacity and to reduce the size of a UB(Gas Circuit Breakers). Major design parameters such as nozzle geometries and interrupting chamber dimensions affect the cooling of the arc and the breaking performance. But it is not easy to test real GCB model in practice as in theory. Therefore, a simulation tool based on a computational fluid dynamics(CFD) algorithm has been developed to facilitate an optimization of the interrupter. Special attention has been paid to the supersonic flow phenomena between contacts and the observation of hat-gas flow for estimating the breaking performance. However, there are many difficult problems in calculating the flow characteristics in a GCB such as shock wave and complex geometries, which may be either static or in relative motion. Although a number of mesh generation techniques are now available, the generation of meshes around complicated, multi-component geometries like a GCB is still a tedious and difficult task for the computational fluid dynamics. This paper presents the CFD program using CFB-CAD integration technique based on Cartesian cut-cell method, which could reduce researcher's efforts to generate the mesh and achieve the accurate representation of the geometry designed by a CAD tools.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1215-1220
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• 2014

Breaking time is an important performance indicator of a circuit breaker. Thus, the operating mechanism of the circuit breaker should be optimized for reducing the breaking time. The operating mechanism in a gas circuit breaker is made up of several latches. Specifically, the geometry and relative positions of latches influence the dynamic behaviors of the operating mechanism. In this study, a three-stage latch operating mechanism is analyzed on the basis of the verified multibody dynamics model constructed using the MSC.ADAMS program. The relative positions and lengths of latches are selected as design variables. The dominant design variables are selected by a design study. Optimization is performed using a genetic algorithm (GA). The study results demonstrate that the performance of the circuit breaker improves by about 22.5.

• Journal of the Korea Institute of Building Construction
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• v.9 no.1
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• pp.111-121
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• 2009

Because of its unique characteristics, the construction industry tends to be affected by economic environment more than any other industries. The domestic construction industry was forced to change its management pattern and system when it went through the foreign currency crisis, and since then, the construction industry has been growing in terms of quality over last 10 years, breaking from the quantitative performance-oriented growth in the past. The study was intended to integrate the financial data of the companies during the period before and after the foreign currency crisis so as to analyze the effect of environmental changes on management performance of the companies. It was aimed at evaluating the changes to the stability, profitability and the growth potential, and collecting the data on variation of the market scale, price of resources such as material and labor and the financial environment, thereby analyzing the correlation with the management performance. The study, to deal with the difficulties which are anticipated, like the foreign currency crisis experienced in the past, was also intended to identify the correlation between the economic conditions and the performance of the construction companies, using the experimental data in the past.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.5
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• pp.108-122
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• 2001

As bridge design is advancing toward the performance-based design. it becomes increasingly important to monitor and re-evaluate the long-term structural performance of bridges. Such information is essential in developing performance criteria for design. In this research. sensor systems for long-term structural performance monitoring have been installed on two highway bridges. Pre1iminary vibration measurement and data analysis have been performed on these instrumented bridges. On one bridge, ambient vibration data have been collected. based on which natural frequencies and mode shapes have been extracted using various methods and compared with those obtained by the preliminary finite element analysis. On the other bridge, braking and bumping vibration tests have been carried out using a water truck In addition to ambient vibration tests. Natural frequencies and mode shapes have been derived and the results by the breaking and bumping vibration tests have been compared. For the development of a three dimensional baseline finite element model, the new methodology using a neural network is proposed. The proposed one have been verified and applied to develop the baseline model of the bridge.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.87-95
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• 2005

value prediction in high performance micro processors is a technique that exploits Instruction Level Parallelism(ILP) by predicting the outcome of an instruction and by breaking and executing true data dependences. In this paper, the mean Performance improvements by predictor according to a point of time for update of each table as well as prediction accuracy and Prediction rate are measured and assessed by comparison and analysis of value predictor that issues in parallel and run by predicting value, which is for Performance improvements of ILP in micro Processor. For the verification of its validity the SPECint95 benchmark through the simulation is compared by making use of execution driven system.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.80-82
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• 1996

This paper deals with the effects of the volume of thermal expansion chamber on the interrupting performance in thermal expansion type 25.8kV 25kA gas circuit breaker. Model interrupters with 5 type thermal expansion chamber were designed and manufactured. Short-circuit tests were carried out for those model interrupters with 25kA breaking current. Pressure rise in the expansion chamber were measured and compared with the calculated one which was obtained from a self-developed program in our team. The analysis on the interrupting performance of each model interrupter has been done on the base of the short-circuit test results.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.10
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• pp.1111-1116
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• 2014

In this paper, in order to improve performance of LDPC codes, we propose an effective algorithm with lowering error floor of LDPC codes. This method is done by breaking trapping sets, mostly caused by an undesirable structure. This algorithm is not need to observe all the errors, only need to break the trapping sets, to effect the effectiveness. Simulation results show that its performance can be significantly improved with this decoding algorithm.

• Korean Journal of Poultry Science
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• v.24 no.1
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• pp.39-44
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• 1997

Two experiments were carried out to determine the effects of pelleting layer diets on the laying perforrnance and nutrients utilizability, using either 50-wk-old(Experiment 1) or 80-wk-old (Experiment 2) layers. There was no effect of pelleting layer diets on hen-day egg production and average egg weight but decreased (P<0.05) feed conversion ratio(intake /egg weight) in both experiments. Although both egg specific gravity and eggshell thickness were not influenced by pelleting eggshell breaking strength was improved(P<0.05) only in Experiment 1. Utilizability of dietary fat was improved(P<0.05) by pelleting layer diets with no difference in other nutrients utilizability. There was no difference in the passage rate of mash and pelleted layer diets.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.321-326
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• 2012

The mechanism unit, arc chamber and trip unit are imperative components of MCCB which will decide the level of performance of MCCB. Among them, Arc chamber unit is used for extinguishing arc rapidly of fault current and induce the arc inside of grid. At that time inducing arc will split into parts and cooled rapidly so the arc would disappear. This paper suggests new arc chamber unit to improve arc extinguishing performance with optimum design and are applied to actual products based on the results.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.169-171
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• 2007

A breaking layer was introduced to conventional decal transfer method in membrane electrolyte assembly fabrication for high catalyst transfer ratio. In this study, the modified decal transfer method with high catalyst transfer ratio was introduced and its performance is studied. The structural features of electrodes made by decal method were investigated using scanning electron microscopy and current-voltage polarization measurement.