• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.345-352
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• 2000

It is very important to evaluate the reliable nonlinear modulus characteristics of soils not only in the analysis of geotechnical structures under working stress conditions but also for the soil dynamic problems. For the evaluation of modulus characteristics of soils, various tests have been mostly employed in laboratory. However, different testing techniques are likely to have different ranges of reliable strain measurements, different applied stress level, and different loading frequencies, and the modulus of soils can be affected by these variables. For reliable evaluation, therefore, those effects on the modulus need to be considered, and measured values should be effectively adjusted to actual conditions where the soil is working. In this paper, to evaluate the modulus characteristics of soils, laboratory testing such as free-free resonant column (FF-RC), resonant column (RC), torsional shear (TS), static TX, and cyclic M/sub R/ tests were performed. The effects of strain amplitude, loading frequency, loading cycles, confining pressure, density, and water content on modulus were investigated. It is shown that the FF-RC test, which is simple and inexpensive testing technique, can provide a reliable estimation of small strain Young's modulus (E/sub max/), and the modulus evaluated by various laboratory tests are comparable to each other fairly well when the effects of these factors are properly taken into account.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.409-413
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• 2006

This paper deals with the design and testing of a simulator system for microgrids with distributed generations. This system is composed of a Real Time Digital Simulator (RTDS) and a power amplifier. The RTDS parts are operated for real time simulation for the microgrid model and the distributed generation source model. The power amplifiers are operated fur amplification of the RTDS's simulated output signal, which is a node voltage of the microgrid and distributed generation source. In this paper, we represent an RTDS system design, specification and test results of a power amplifier and simulation results of a PV (Photovoltaic) system and wind turbine system. The proposed system is applicable for development and performance testing of a PCS (Power Conversion System) for renewable energy sources.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1957-1959
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• 2000

The PD measurement method is very useful to detect insulation degradation. Recently, the HFPD(High Frequency Partial Discharge) measurement testing is widely used in partial discharge measurement of HV machines because HFPD measurement testing receives less influence of external noise and has a merit of good sensitivity. Therefore it is very useful method compare to previous conventional PD testing method and effective diagnosis method in power transformer that requires in-service diagnosis. But partial discharges have very complex characteristics of discharge pattern so it is required continuous research to development of precise analysis method. In this study, simulated transformer is manufactured and HFPD occurred from simulated transformer is measured with broad band antenna and active-line RF measurement system in real time, the degradation grade of transformer is analyzed through produced patterns in simulated transformer according to applied voltages. Also the PD pattern which was measured with EMC analyzer and RF measurement system is compared.

• Nuclear Engineering and Technology
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• v.46 no.2
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• pp.169-182
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• 2014

High-performance research reactors require fuel that operates at high specific power to high fission density, but at relatively low temperatures. Research reactor fuels are designed for efficient heat rejection, and are composed of assemblies of thin-plates clad in aluminum alloy. The development of low-enriched fuels to replace high-enriched fuels for these reactors requires a substantially increased uranium density in the fuel to offset the decrease in enrichment. Very few fuel phases have been identified that have the required combination of very-high uranium density and stable fuel behavior at high burnup. U-Mo alloys represent the best known tradeoff in these properties. Testing of aluminum matrix U-Mo aluminum matrix dispersion fuel revealed a pattern of breakaway swelling behavior at intermediate burnup, related to the formation of a molybdenum stabilized high aluminum intermetallic phase that forms during irradiation. In the case of monolithic fuel, this issue was addressed by eliminating, as much as possible, the interfacial area between U-Mo and aluminum. Based on scoping irradiation test data, a fuel plate system composed of solid U-10Mo fuel meat, a zirconium diffusion barrier, and Al6061 cladding was selected for development. Developmental testing of this fuel system indicates that it meets core criteria for fuel qualification, including stable and predictable swelling behavior, mechanical integrity to high burnup, and geometric stability. In addition, the fuel exhibits robust behavior during power-cooling mismatch events under irradiation at high power.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.18-27
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• 2020

This study compared and analyzed the results of proficiency testing between testers based on the international standard ISO/IEC 17043 proficiency testing requirements using ISO/IEC 25023 software quality characteristics evaluation. Application of the test was submitted to the KASTO as a software test in the electric test field defined by KOLAS. Among ISO/IEC 25023, the evaluation items for proficiency testing between testers were selected as functional completeness and time behavior. The comparison test between testers was carried out on May 28, 2019 at the accredited LG Electronics SW Laboratory in Seoul and attended by KOLAS assessors. The test evaluation method was measured once per tester with functional completeness, and measurement was repeated 10 times per tester according to time behavior. As a result, in the case of functional completeness, all 12 test steps were passed, and the satisfaction was evaluated. Time behavior was repeated 10 times, and the mean was 9.45 ± 0.01 seconds for testers 1 and 3 and 9.52 ± 0.0 seconds for tester 2, but there was no statistically significant difference. In conclusion, the proficiency of the testers was equal, and the reliability of the test results of the test institute was confirmed.

• Journal of the Korean GEO-environmental Society
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• v.17 no.10
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• pp.23-31
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• 2016

Grout is generally operated with low viscous material similar to water, but grout for micro crack with high viscous materials and high injection pressure is gradually increased under the development of underground and subsea space. In order to estimate grouting injection performance considering crack width, viscosity of grouting materials, and injection pressure, there should be a reliable standard laboratory testing method. In this paper, theoretical injection mechanisms of grouting materials are presented as radial and linear flows, and laboratory testing apparatus are introduced to simulate each flow case. Radial flow is simulated by using acrylic disk plates which are able to spread grouting material radially from the center of the disk plates, and linear flow is simulated by using stainless parallel plane plates which are able to spread grouting material linearly. Apparatus are consist of upper and lower plates and industrial films with different thickness are placed between plates in order to simulate various crack widths. Laboratory verification tests with these apparatus were conducted with tap water (1cP at $20^{\circ}C$) as an injection material. Through the laboratory testing results, the best laboratory testing method is recommended in order to estimate grouting injection performance.

• Journal of Korean Society for Quality Management
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• v.23 no.4
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• pp.128-147
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• 1995

An accelerated life testing(ALT) for aluminum electrolytic capacitors is conducted and analyzed. A testing equipment, which consists of part fixtures, relay board, controller, video bridge and microcomputer, is made for the ALT. Load factors are temperature with four levels and voltage with three levels. Base on 'optimized 4:2:1 plan', 2,000 electrolytic capacitors are allocated at 12 experimental conditions(; 4 levels of temperature ${\times}3$ levels of voltage), and the ALT is conducted. From the experimental results, an acceleration model is derived and acceleration factors are estimated. A discussion on the experimental results is included.

• IE interfaces
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• v.25 no.4
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• pp.416-421
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• 2012

One of the activities to improve software quality in ISO 26262 is to apply the design principles for software unit design and implementation mentioned in ISO 26262-6, including the evaluation activity. Before evaluation activity, the tool is compared and selected for evaluation. Because the results of the tool a company selected might have an effect on product quality. In this paper, we suggest the method to compare industrial static analysis tools with some of "MISRA C : 2004 Exemplar Suite" and all lessons learned from comparing tools are described. The result on comparison shows that we just couldn't rely on a result of Static Analysis Tool and need to have another appropriate processes and guidelines to evaluate a software.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1551-1552
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• 2015

현재 태양광인버터의 안전성확보에 대한 기술기준이 IEC로부터 채택하게 됨과 동시에 독일, 일본, 미국 등 선진 각국에서는 안전성 확보용 기술기준을 적용하고 있으며, 강제(Mandatary) 규격으로 적용하고 있는 상태이다. 그러나 국내 태양광인버터분야는 인버터의 성능만 수행하고 있는 상태이며, 안전성분야는 전무한 상태이다. 따라서 본 논문에서는 성능위주의 특성에서 벗어나 사용자의 보호 및 안전성을 중심으로 CE, UL 등의 해외인증에서 요구하는 기준으로 자리를 잡아가고 있는 IEC 62109 표준화에 대한 정확한 기술기준 및 시험방법에 대해 살펴본다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.163-166
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• 2006

The purpose of the research is to assess the accuracy of steel bar detector among other nondestructive testing equipment. The result of previous research shows that the average errors of rebar detector are 14.7% for the cover depth, 2.3% for the rebar spacing, and 11% for the rebar diameter. But this experiment was performed at the laboratory and the mortar was used for covering the steel bars instead of concrete. In situ condition can be different from the laboratory's so the outcomes do not correspond with those of laboratory. This research was performed at the buildings to be reconstructed. Nondestructive and destructive testing can be performed side by side since the building if to be destroyed. Steel bar detector was operated on the beam and the column and concrete cover of those members was removed for the actual measurement of rebar depth, spacing, and diameter finally, presumed value can be directly compared with actual data.