• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.843-844
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• 2012

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.2
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• pp.190-197
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• 2002

In this thesis, ZnO varistors with various formulation, such as A∼E, were fabricated according to ceramic fabrication method. The microstructure, electrical properties, and surge characteristics of ZnO varistors were investigated according to ZnO varistors with various formulation. In the microstructure, A∼E\`s ZnO varistor ceramics sintered at 1130$\^{C}$ was consisted of ZnO grain(ZnO), spinel phase (Zn$\_$2.33/Sb$\_$0.67/O$\_$4/), Bi-rich phase(Bi$_2$O$_3$) and intergranuler phase, wholly. Lightning impulse residual voltage of A, B, C and E\`s ZnO varistors suited standard characteristics, below 12kV at current of 5kA. On the contrary, D\`s ZnO varistor exhibited high residual voltage as high reference voltage. In the accelerated aging test, leakage current and watt loss of B, C and D\`s ZnO varistors increases abruptly with stress time under the first a.c. stress(115$\^{C}$/3.213kV/300h). Consequently, C varistor exhibited a thermal run away. On the contrary, leakage current and watt loss of A and C\`s ZnO varistors which show low initial leakage current exhibited constant characteristics. After high current impulse test, A\`s ZnO varistor has broken the side of varistor but impulse current flowed. On the contrary, E\`s ZnO Varistor exhibited good discharge characteristics which the appearance of varistor was not wrong such as puncture, flashover, creaking and other significant damage. After long duration impulse current test, E\`s ZnO varistor exhibited good discharge characteristics which the appearance of varistor was not wrong such as puncture, flashover, creaking and other significant damage. After high current impulse test and long duration impulse current test, E\`s ZnO varistor exhibited very good characteristics which variation rate of residual voltage is 1.4% before and after test.

• Korean Journal of Veterinary Service
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• v.24 no.1
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• pp.51-68
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• 2001

The result of studying the epidemiological characteristics of Salmonella strains which have been isolated from the domestic animals in Gyeongbuk province from February 1998 to August 2000 were summarized as follows. The isolation rates of Salmonella strains were 2.0% from cattle feces, 6.3% from cattle lymph node, 9.5% from pig feces, and 25.1% from pig lymph node. In poultry, the isolation rates were 30.3%. The isolates of Salmonella showed positive reaction for MUCAP test, methyl red test, but showed negative reaction for urea test, indole test, Voges Proskauer test. On TSI agar, the isolates showed acid butt, alkaline slant. Also, the isolates were identified as Salmonella strain by API 20E kit. Non H$_2$S Production Salmonella strains isolated from poultry were identified as S gallinarum. As a result of serotyping, B group were the most common in cattle and pig, Dl in chickens. 21 serovars were found. the common serovar from the domestic animals was S typhimurium, S derby, S agona, S schwarzenground, S enteritidis and S gallinarum. The most commonly encountered serovars in cattle were S agona and S typhirimurium in pig, S gallinarum in chicken. As a result of antimicrobial susceptibility test, all Salmonella isolates were susceptible to amikacin, ciprofloxacin, norfloxacin; cefotaxime and polumcin B. The resistance rates to tetracycline and streptomycin was 58% and 56%, respectively. 69.3% of all isolates were resistant to more than one antimicrobial agent. Out of the resistant isolates, the isolates resistant to streptomycin and tetracycline was 36%. There were 24 strains of multiresistant isolates resistant to more than 5 antimicrobial agents. S typhimurium were resistant to all antimicrobial agents, also had a lot of multiresistant strains. Therefore, S typhimurium was considered as a major agent of antimicrobial resistance.

• Journal of Korean Society on Water Environment
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• v.21 no.3
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• pp.274-276
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• 2005

To investigate bioassay for toxic level evaluation of wastewater, toxic levels were checked influents and effluents of 6 wastewater discharge facilities with Daphnia magna and Vibrio fischeri. In view of test duration, D. magna is preferred at 48 hours. And it was judged to efficient that one of the two was choosen for toxicity test method (Daphnia test and Vibrio test). Analysis data for wastewater is average toxic level for influent more higher than effluent. And effluent toxic level is sharp decrease than effluents.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.1
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• pp.7-13
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• 1985

Design techniques for programmable storage/logic arrays(SLA's) with easily testable features are discussed. The easily testable SLA's will be designed by using additional hardware to provide an easy means to set or check the states. These augmented SLA's have the very short universal test sequences such that the test patterns and responses are uniquely determined only by the size of the SLA's independently of the function of them. The types of faluts considered here are single and multiple stuck faults, crosspoint faults, and bridge faults in SLA's. Fault location and reapir of SLA's are also considered.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.454-456
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• 2003

This paper describes a type test results of 154 kV transmission line arrester with external gap. The test was carried on surge arrester unit and line arrester with external gap, respectively. Withstand voltage test demonstrate the voltage withstand capability of the line arrester with external series gap under the dry and wet conditions. In insulation coordination test external series gap shall be discharged every time when lightning impulse voltage with the steepness of more than 1500 $kV/{\mu}s$ are applied under the wet condition.

• International Journal of Reliability and Applications
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• v.14 no.1
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• pp.1-9
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• 2013

A nonparametric procedure for testing exponentially against used better than aged in expectation (UBAE) class of life distributions is presented. We construct a test statistics based on scaled total time on test (TTT)-transformation, to test exponentiality against UBAE class of life distributions. The distribution of the statistic is investigated via simulation. Practical applications of the proposed test are presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.6
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• pp.715-723
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• 2018

The energy storage system consists of batteries, power conditioning system and energy management system. If ESS is installed and operated in the field, SAT(Site Acceptance Test) of ESS is being essentially required for the safety and performance of ESS. Furthermore, in order to more accurately and reliably validate the performance of the ESS in advanced countries, it has been required to perform not only performance testing by H/W equipments but also performance verification by S/W tool. Therefore, this paper proposes the modeling of portable test equipment in order to evaluate the performance and reliability of ESS by using the PSCAD/EMTDC S/W. And also, the prototype of 30[kW] scaled portable test equipments is implemented based on the S/W modeling. From the results of various simulations and testings such as power quality, LVRT and anti-islanding tests, it is confirmed that 30[kW] scaled portable test equipment is useful for SAT of ESS, because the simulation results of PSCAD/EMTDC are identical to them of 30[kW] test equipment at the same test conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.491-492
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.34-38
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• 2005

This paper describes the result of load test of a bogie frame. The purpose of test is to evaluate the safety which bogie frame shall be considered fully sufficient rigidity so as to satisfy proper system function under maximum load. Bogie system consist of the bogie frame, suspensions, wheel-sets, a brake system and a transmission system. Among these component, the bogie frame is most significant component subjected to the vehicle and passenger loads. The evaluation method is used the JIS E 4207 specifications throughout the static load test. The test results have shown the bogie frame to be safe and stable under design load conditions.