• Title/Summary/Keyword: SWC

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A Study on the Development of Controller which is used Electric Operating Cell(EOC) for Vacuum Circuit Breaker and the Controller Performance Certification Test (진공차단기용 전자식 보조접점 컨트롤러 개발 및 성능인증시험에 관한 연구)

  • Lee, Ki-Seon;Park, Jung-Cheul;Chu, Soon-Nam
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.64 no.3
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    • pp.130-137
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    • 2015
  • This study is about the controller development of the Electric Operating Cell(EOC) which will replace the Mechanical Operated Cell(MOC) of the vacuum circuit breaker which has been used in the power plant and the performance test for the developed controller. The controller developed through this study was manufactured considering the harsh installation environment and electrical condition of the power plant, and the controller performance certification test for confirming the product reliability was taken to know whether or not to withstand fully in various electrical and mechanical problems. Items for performance certification test were AC power frequency voltage withstand test, combined surge immunity test, 1 [MHz] oscillatory SWC test, fast transient SWC test, radiated electromagnetic interference test, vibration test. As a result, all tests has passed an examination without malfunction.

Evaluation of a Hydro-ecologic Model, RHESSys (Regional Hydro-Ecologic Simulation System): Parameterization and Application at two Complex Terrain Watersheds (수문생태모형 RHESSys의 평가: 두 복잡지형 유역에서의 모수화와 적용)

  • Lee, Bo-Ra;Kang, Sin-Kyu;Kim, Eun-Sook;Hwang, Tae-Hee;Lim, Jong-Hwan;Kim, Joon
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.9 no.4
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    • pp.247-259
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    • 2007
  • In this study, we examined the flux of carbon and water using an eco-hydrological model, Regional Hydro-Ecologic Simulation System (RHESSys). Our purposes were to develop a set of parameters optimized for a well-designed experimental watershed (Gwangneung Research Watershed, GN) and then, to test suitability of the parameters for predicting carbon and water fluxes of other watershed with different regimes of climate, topography, and vegetation structure (i.e Gangseonry Watershed in Mt. Jumbong, GS). Field datasets of stream flow, soil water content (SWC), and wood biomass product (WBP) were utilized for model parameterization and validation. After laborious parameterization processes, RHESSys was validated with the field observations from the GN watershed. The parameter set identified at the GN watershed was then applied to the GS watershed in Mt. Jumbong, which resulted in good agreement for SWC but poor predictability for WBP. Our study showed that RHESSys simulated reliable SWC at the GS by adjusting site-specific porosity only. In contrast, vegetation productivity would require more rigorous site-specific parameterization and hence, further study is necessary to identify primary field ecophysiological variables for enhancing model parameterization and application to multiple watersheds.

Spatio-Temporal Changes and Drivers of Deforestation and Forest Degradation in North Korea (북한 산림의 시·공간 변화와 황폐화 추동)

  • Yu, Jaeshim;Kim, Kyoungmin
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.18 no.6
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    • pp.73-83
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    • 2015
  • The objective of this study is to establish implications for forest restoration planning in North Korea by analyzing spatio-temporal forest changes and detecting bio-physical factors driving forest degraded. We measured the relationship and spatial distribution between shifting cultivation and sparse forest. We also analyzed between degraded forest land and ecological variables by binary logistic regression to find biophysical drivers of forest degradation and deforestation in North Korea. Between the sparse forest and the shifting cultivation, a positive relationship is found (r=0.91) and scattered discontinuously throughout the country (Moran's I = -1, Z score = -13.46 (p=0.000)). The sparse forest showed a negative relationship with the warmest month(bio 9), the coldest month(bio10), and the minimum of soil water contents (swc_min), while the shifting cultivation had a negative relationship with the warmest month(bio 9) and the minimum of soil water contents(swc_min). However, the most critical drivers convert forests into sloping farmland were the three months rainfall in summer(bio8) and the yearly mean of soil water contents. Such results reflect the growth period of crops which overlaps with the rainy season in North Korea and the recent land reclamation of uplands where the soil water contents are maintained with a dense forest. When South Korea aids forest restoration projects in North Korea, in consideration of food shortage due to North Korea's cropland deficiency, terrace farmlands where soil water contents can be maintained should be excluded from the priority restoration area. In addition, an evaluation method for selecting a potential restoration area must be modified and applied based on multiple criteria including altitude and socio-economic factors in the respective regions.

Hot Spot Prediction Method for Improving the Performance of Consistent Hashing Shared Web Caching System (컨시스턴스 해슁을 이용한 분산 웹 캐싱 시스템의 성능 향상을 위한 Hot Spot 예측 방법)

  • 정성칠;정길도
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.5B
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    • pp.498-507
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    • 2004
  • The fast and Precise service for the users request is the most important in the World Wide Web. However, the lest service is difficult due to the rapid increase of the Internet users recently. The Shared Web Caching (SWC) is one of the methods solving this problem. The performance of SWC is highly depend on the hit rate and the hit rate is effected by the memory size, processing speed of the server, load balancing and so on. The conventional load balancing is usually based on the state history of system, but the prediction of the state of the system can be used for the load balancing that will further improve the hit rate. In this study, a Hot Spot Prediction Method (HSPM) has been suggested to improve the throughputs of the proxy. The predicted hot spots, which is the item most frequently requested, should be predicted beforehand. The result show that the suggested method is better than the consistent hashing in the point of the load balancing and the hit rate.

Scheduling Design and Simulation of Software Components for EPS System based on AUTOSAR (AUTOSAR기반 EPS 시스템 소프트웨어 컴포넌트의 스케줄링 설계 및 시뮬레이션)

  • Park, Gwang-Min;Kum, Dae-Hyun;Son, Byeong-Jeom;Lee, Seong-Hun
    • Journal of Institute of Control, Robotics and Systems
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    • v.16 no.6
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    • pp.539-545
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    • 2010
  • Through the AUTOSAR methodology, the embedded software shall become more flexible, reusable, maintainable than ever. However, it is not mentioned about specific timing constraints of software components in AUTOSAR. There are a few basic principles for mapping runnable entities. At this point, AUTOSAR software design with optimal scheduling method is one of the enabling technologies in vehicle embedded system. This paper presents an approach based on mapping runnable entities and task scheduling design method for EPS (Electric Power Steering) software components, based on AUTOSAR. In addition, the experimental results of concurrent simulation show that the proposed scheduling technique and timing synchronization in the software component design can achieve the improved torque ripple performance and it well suited for EPS application software.

Running Inverse for Implementing Decorrelating Detectors in Synchronous DS/CDMA Systems

  • Joo, Jung-Suk;Lee, Yong-Hoon
    • Journal of IKEEE
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    • v.2 no.2 s.3
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    • pp.294-298
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    • 1998
  • We propose an efficient method for updating the inverse of the signature waveform cross-correlations (SWC) matrix when the number of users in the synchronous direct-sequence code-division multiple-access (DS/CDMA) system changes. It is shown that the computational complexity of the proposed method is $O(n^2)$ in which n represents the number of active users in the system.

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Fatigue Characteristics of Tension Spring for LCD Monitor Hinge (LCD 모니터 힌지용 인장 스프링의 피로특성)

  • Cheong, Seon-Hwan;Choi, Seong-Dae;Kim, Ki-Man;Byun, Yong-Kun;Yang, Seung-Cheol
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.6 no.1
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    • pp.13-19
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    • 2007
  • The spring is an important mechanical parts to improve the functions of precision machines, automobiles, ships, industrial machines, and IT devices etc.. The hinge mechanism for LCD monitors is very important to support and maintain the proper position of monitor panel, and the tension spring which is a major parts of hinge mechanism plays a significant roll to provide the supporting force positioning the monitor panel. In this paper, an analysis and experiment were carried out to investigate the fatigue characteristics of the tension spring of hinge mechanism, such as hardness test, fatigue test and fractography analysis. As a result of this study the SWPB with heat treatment and shot peening was found to have the optimal design conditions of tension spring for LCD monitor hinge mechanism.

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A Study on the Optimal Structural Design and Ultra Precision Position Control using FEM for Micro Stage (마이크로 스테이지의 유한요소법을 이용한 최적설계와 초정밀 위치제어에 관한 연구)

  • Kim, J. Y.;Han, J. H.;Kim, H. W.;You, S.;Kwac, L. K.;Song, I. S.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.336-340
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    • 1997
  • For optimal design of micro stage, we were measured to displacement of piezo-electric transducer that was based on voltage value. And then researchers were analyzed to microstage through FEM with displacement data including voltage value of piezo-electric transducer. For verification of analyzing results, we were gauged on displacement by using Laser-interferometer. And researchers were confirmed to propriety of micro stage design with FEM, were obtained error rate that are 3.5% between measurement results and analyzing results.

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Distributed Channel Allocation Using Kernel Density Estimation in Cognitive Radio Networks

  • Ahmed, M. Ejaz;Kim, Joo Seuk;Mao, Runkun;Song, Ju Bin;Li, Husheng
    • ETRI Journal
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    • v.34 no.5
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    • pp.771-774
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    • 2012
  • Typical channel allocation algorithms for secondary users do not include processes to reduce the frequency of switching from one channel to another caused by random interruptions by primary users, which results in high packet drops and delays. In this letter, with the purpose of decreasing the number of switches made between channels, we propose a nonparametric channel allocation algorithm that uses robust kernel density estimation to effectively schedule idle channel resources. Experiment and simulation results demonstrate that the proposed algorithm outperforms both random and parametric channel allocation algorithms in terms of throughput and packet drops.

A study on the Potential Detection System of Gas Insulated Switchgear (가스절연개폐장치의 전위감지 시스템에 대한 연구)

  • Choi, Seung-Kil;Baek, Seung-Kook;Kim, Kwang-Ho;Kang, Hyung-Boo
    • Proceedings of the KIEE Conference
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    • 1999.07e
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    • pp.2284-2286
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    • 1999
  • This paper describes the development of potential detection system in 22.9kV gas insulated switchgear. This system composed with main system and LPS can detect the source voltage by capacitive potential division which is accomplished by inserting signal electrode between main electrode and earthed metal enclosure of the switchgear. The appropriate position of signal electrode is achieved by numerical analysis using finite element method. The developed potential detection system is verified by several tests such as voltage test, swc test and others and by applicaion at site. From the results, it is concluded that potential detection system is very reliable and available to operate the switchgear safely.

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