• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.169-172
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• 2005

The performance test result of the Arm Fire Device(Ignition Safety Device) for solid rocket which prevents accidental ignition was described. The results of the closed bomb test and the igniter test of the classical mechanical arm fire device and the advanced electro-mechanical arm fire device were presented, and according to the igniter test result it was realized that the electro-mechanical arm fire device has an advantage in aspect of the action time.

• Broadcasting and Media Magazine
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• v.7 no.1
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• pp.94-106
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• 2002

미국 지상파방송방식 ATSC의 전송방식(8-VSB)과 유럽지상파방송방식 DVB-T의 전송방식(COFDM)에 대한 현장비교시험이 서울을 비롯한 수도권 일원에서 2001년 9월 18일부터 2001년 11월 28일까지 약 3개월에 걸쳐 실시되었다. 이 시험에서는 도심지, 방사선, 원거리, 계층변조, 실내수신, 이동수신 등 6가지 유형에 대해 측정이 수행되었다. 측정결과, 유럽식이 미국식에 비해 모든 측정유형에서 우수한 성능을 보였다. 산악이 많고 도시에 건물이 밀집되어 다중경로간섭의 영향이 큰 한국의 환경에서는 유럽식이 더 적합한 방식임이 이 시험을 통해 입증되었고, 특히 이동수신의 경우 미국식은 거의 수신이 불가능한데 비해 유럽식은 표준화질에서 95%이상, 상당히 높은 고화질에서 70%이상의 수신율을 보여 미래의 새로운 서비스에 대한 적응성에서도 유럽식이 우수한 것으로 평가되었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.465-467
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• 2012

A layout plan of a pressure-fed test facility to carry out hot-firing test of liquid rocket engine combustion chamber and purpose of rooms located in the test building were proposed. The layout plan of suggested infrastructure in this paper was determined depending on the design of a vertical test facility to use the natural lay of the land and simulate the initial position of flight model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5923-5929
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• 2013

Recently, the retaining wall with the relieving platform has received increasing interests also in Korea in that it can reduce the lateral earth pressure and provide more stability than conventional retaining wall. Previous studies with model tests studies covered only a limited test conditions. In this study, total 15 model tests were performed for various conditions with improved model test apparatus to confirm the effect of decreasing the lateral earth pressure on the retaining wall with the relieving platform. Jumoonjin sand was used for model soil and 2 load cells were used for each 15 layers to measure the lateral earth pressure. Based on the experimental results, the lateral earth pressure of the retaining wall with the relieving platform is less than the that of cantilever wall. The length of the platform and the location of the platform are the key factors influencing the lateral earth pressure.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.123-128
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• 2004

본 논문에서는 가속 수명 시험을 통하여 열전소자의 수명 분포, 모수 등을 규명하였으며 고장 분석을 통하여 열전 소자의 수명 증가를 위한 대책 방안을 논의하였다. 가속 수명 시험 결과 열전 소자는 형상 모수 3,6인 Weibull 분포를 따름을 알 수 있었다. 열전 소자가 반도체 부품임에도 불구하고 형상 모수가 큰 이유는 반복 Bending에 의한 피로 파괴가 발생하기 때문임을 고장 분석을 통하여 규명하였다. 위의 고장 메커니즘을 설명할 수 있는 가속 모델식은 Coffin-Manson식으로 설명되어 질 수 있으며 가속수명시험 결과 재료 상수는 1.8임을 알 수 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.2
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• pp.178-183
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• 2012

To simulate space thermal environment in thermal vacuum test, direct or in-direct heater has been applied on the radiator. Both of them, direct heater attached on the radiator and indirect heater with a distance from the radiator, simulate the heat fluxes from the Sun radiation, the Earth IR and Albedo. They also supply the heat fluxes to the radiator of spacecraft to achieve the target temperature according to thermal test conditions. In general, indirect heater is used when the heater is not allowed to attach on the radiator directly due to constraints of coating property or contamination. For in-direct heater design, it is needed to estimate the heat power to make the extreme test conditions and minimize the interference with heat exchange of radiator and shroud. In this study, optimized thermal design of in-direct heater is proposed and investigated by commercial S/W SINDA. The effective values of design factors are also derived.

• Journal of the Korean GEO-environmental Society
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• v.7 no.2
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• pp.15-24
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• 2006

In this paper, the Coefficient of Subgrade Reaction was analyzed from the data which were the results of lateral pile loading tests and pressuremeter tests on construction sites. The prediction method with N-value was compared with lateral pile loading tests and the results of lateral pile loading tests were compared with the prediction method considering diameter of a pile. Also, the results of lateral pressuremeter tests were compared with those of lateral pile loading tests. As a result, consideration for a diameter and lateral deformation of a pile was needed when the coefficient of horizontal subgrade reaction is presumed. Therefore, a formula which is taking into account the allowable deformation of a pile was suggested from lateral pressuremeter tests in this study.

• Bulletin of the Korean Space Science Society
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• 2004.04a
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• pp.83-83
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• 2004

상용프로그램인 AMESim을 이용하여 제어밸브 성능시험설비에 대한 Transient 구간에서 문제점 발생 확인과 동시에 시스템에 최적화를 통한 비용 절감효과를 위해 본 Simulation을 수행하였다. 가압 자동 조절 시스템은 직렬식과 병렬식 두 가지에 대해 고려했을 경우 직렬식이 더 타당함을 확인하였고, 특히 Tank Ullage의 압력 분포를 보면 직렬식에서 Fluctuation이 약 $\pm$0.2%이고, 병렬식에서 약 $\pm$0.7%가 됨을 보았다. (중략)

• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.705-712
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• 2004

To investigate the mechanical behavior of pin cups created from steel pipes embedded in concrete, test blocks were made and load tests were conducted. The pin was inserted in the pin cup at various depths and was loaded in a lateral direction at a constant displacement speed. A formula, which took into consideration the deformation and failure shapes of the pin cups, observed during and after the tests, was used to estimate its mechanical behavior. The test values were determined to be relevant to the formula and were distributed within a reasonably narrow range. The mean and the 95% survival probability value of maximum resistance were determined by factoring the formula at 1.01 and 0.92, respectively.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.103-116
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• 2008

In this study, in-situ testing method, Dynamic Cone Penetration Test(DCPT) was presented to establish a new compaction control criteria with using mechanical property like elastic modulus instead of unit weight for field compaction control. Soil chamber tests and in-situ tests were carried out to confirm DCPT tests can predict the designed elastic modulus after field compaction, and correlation analysis among the DCPT, CBR and resilient modulus of sub grade were performed. Also, DCPT test spacing criteria in the construction site was proposed from the literature review. In the result of laboratory tests, Livneh's equation was the best in correlation between PR of DCPT and CBR, George and Pradesh's equation was the best in the predicted resilient modulus. In the resilient modulus using FWD, Gudishala's equation estimates little larger than predicted resilient modulus and Chen's equation estimates little smaller. And KICT's equation estimates the modulus smaller than predicted resilient modulus. But using the results of laboratory resilient modulus tests considering the deviatoric and confining stress from the moving vehicle, the KICT's equation was the best. In the results of In-situ DCPT tests, the variation of PR can occur according to size distribution of penetrate points. So DCPT test spacing was proposed to reduce the difference of PR. Also it was shows that average PR was different according to subgrade materials although the subgrade was satisfied the degree of compaction. Especially large sized materials show smaller PR, and it is also found that field water contents have influence a lot of degree of compaction but a little on the average PR of the DCPT tests.