• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.64-70
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• 2010

High capacity UPS and emergency generators are commonly employed at facilities where power interruption is not allowed. Nowadays, combinations of existing commercial incoming power and an emergency generator or combination of multiple generators and CTTS(Closed Transition Transfer Switch) is adopted sometimes for more reliable power supply. In this paper, application of CTTS and STS(Static Transfer Switch) to dual-power line is suggested for highly reliable uninterruptible power. By realizing such a system, construction of incoming power facilities, installation of emergency generator and large capacity UPS can be omitted, through which saving of the installation space and corresponding capital investment can be expected.

• Journal of Animal Environmental Science
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• v.5 no.2
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• pp.101-106
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• 1999

This study was conducted to develop a lignite coal heater which can be used to livestock facilities and to test performance of the heater developed. Experimental results are as following: 1. Heating capacity of the heater was 85,000 kcal/h. 2. The concentrations of CO gas in the exhaust gas were the maximum of 759 ppm and the average of 319 ppm; for the concentrations of NOx, the maximum of 212 ppm and the average of 57 ppm ; for the concentrations of SO2 gas, the maximum of 302 ppm and the average of 99 ppm. As the values were less than the allowable concentration limites, they did not violate the air environment law. 3. Problems such as frequent interruption of fuel supply and bridge state were happened. Therefore, it was required that these should be resolved in the future.

• The KIPS Transactions:PartC
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• v.12C no.1 s.97
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• pp.77-82
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• 2005

Protection of user service becomes increasingly important since even very short interruption of service due to link or node failure will cause huge data loss and incur tremendous restoration cost in high speed network environment. Thus fast and efficient protection and restoration is one of the most important issues to be addressed. Protection methods have been proposed to provide efficiency and stability in optical networks. In this paper, an original network is separated into several domains using Hamiltonian cycle. and link protection is performed on the cycles of the domains. We have shown that protection path length can be decreased up to $57{\%}$ with marginal increase of backup capacity. Our proposed method can provide high-speed protection with marginal increase of protection capacity.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.764-766
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• 2002

본 연구에서는 가스 차단기의 소전류 차단성능을 개선하기 위한 최적화 과정에 대해서 나타낸다. 목적함수는 절연내력과 극간 인가전압의 차이의 최소값으로 선정하였으며, 목적함수가 최대가 되도록 최적화를 수행한다. 설계 변수로는 개극 전의 전극 이동길이, 노즐목 길이 및 노즐목 발산각과 노즐 하류장 형상을 채택하였다. 최적화 알고리즘으로는 (1+1) 진화알고리즘을, 유동해석을 위해서는 FVFLIC법을 사용하였다. 최적화 결과로 얻어진 모델은 초기 모델에 비해 소전류 차단성능이 상당히 개선되었음을 확인할 수 있었다.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.652-659
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• 2011

Due to overuse of commercial network systems such as bluetooth and WI-FI, the problems of frequency interruption and line-crossing may arise. For this reason, wireless communication frequency ISM 2.4GHz, a recently adapted concept in Korea which is employeed by RF-CBTC system, is predicted not to have guarantee for outstanding and continuous performance. Therefore in this study, considering these problems, 5GHz capacity wireless Lans with international standard 802.11a/b/g applied were installed in the underground urban transit areas and it was proved that these lans exceeded the performance level of 2.4GHz with international standard 802.11b which is being introduced in the nation. In addition, it was verified through carrying out an application test that the communication condition was stable in a running train with high speed in the tunnel.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.19-22
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• 2005

In order to achieve high capacity and reliable link quality in user communication, this paper proposes a new concept of virtual cell: the Dual Virtual Cell(DVC), and DVC employment strategy based on DWCS. The proposed system uses two kinds of virtual cell. One is the AVC(Active Virtual Cell) which exists for actual traffic and the other is the CVC(Candidate Virtual Cell) which contains a set of candidate antennas to protect user's link quality from performance degradation or interruption. And also this system aims to reduce MT's overloads and acheive a prompt link change successfuly by introducing DVC structure which makes it possible for network to monitor real-time channel and to conrol communication links. The proposed system constructs DVC by using antenna selection method and improves frame error performance with employing Space-Time Trellis Code(STTC).

• Journal of the Optical Society of Korea
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• v.19 no.4
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• pp.351-356
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• 2015

Visible light communication (VLC) is considered to be an attractive scheme to realize the broadband wireless communication for an indoor environment. We present a room division multiplexing (RDM) mechanism for an indoor multi-room VLC network, which utilizes the spatial position of the LED lamp in different rooms as a novel dimension of network resource for multiplexing, and thus the network capacity is increased. In such a network, the service interruption caused by user cross-room movement is an important problem, and we propose a double-area-positioning based cross-room switch solution. An experimental platform demonstrates the RDM-deployed VLC network, and validates the performance of the presented switch mechanism.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1362_1363
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• 2009

In this study, we predicted the thermal breakdown of high-voltage interrupter with the characteristics of thermal plasmas such as temperature, pressure and concentration of the ablated material by using a commercial CFD program. The results showed that the pressure build-up inside the chamber was proportional to the magnitude of arcing current because the quantities of heat energy and ablated mass also increase together with the current during the compression process. And during the decompression process, the reverse flow was not coincided with the magnitude of the applied current due to the compressibility of the gas through backflow channel. The present method is expected to be useful for the design of guideline and interruption capacity on the thermal breakdown of a PASB chamber.

• Proceedings of the KIEE Conference
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• 2008.04b
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• pp.123-124
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• 2008

Battery is one of the emergency power. Battery reliability is a very important to keep up the minimum of building capabilities in case of interruption of electric power. Instantaneous discharge test is carried out for measuring transient voltage change(${\Delta}V$) and internal instantaneous impedance(Z), and then it is compared with discharge test results for the estimating the battery capacity. As a result, it was confirmed that the voltage change(${\Delta}V$) and the instantaneous impedance of the batteries failed in actual discharge test were higher that those of the sound batteries. Such an instantaneous discharge test can be a diagnosis of battery sound.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.569-571
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• 2005

In case of dead-tank circuit breaker with the earthed enclosure, the dielectric performance for phase to ground should be verified under the hot-gas condition produced by the current interruption. This test condition is required in breaking test duties with the rated short-circuit current and rated voltage. And, KERI has completed the reinforcement of the synthetic testing facilities and these facilities have the testing capacity which enables the full-pole testing for 800kV circuit breaker by adopting the series voltage injection method. So, this paper introduced the test circuit and procedures about the full-pole and the multi-part testing method which was devised to estimate the full -insulation of phase-to-ground for the multi-pole and dead-tank circuit breaker.