• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.2
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• pp.56-61
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• 2011

Performance test of a full-scale turbopump assembly for a 75 ton class liquid rocket engine was carried out at full speed. Model fluid was used as a working medium: liquid nitrogen for the oxidizer pump, water for the fuel pump, and hot air for the turbine. The turbopump was operated stably, satisfying the performance requirements. Head coefficient and flow coefficient of the pumps remained constant at the speed-increasing period. In terms of performance characteristics of pumps and turbine, the results from the turbopump assembly test showed a good agreement with those from the turbopump component tests.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.1
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• pp.18-22
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• 2006

Hydrodynamic performance test was conducted for a fuel pump of a liquid rocket engine turbopump. The pump driven by an electric motor was tested using water. It is experimentally shown that the inducer had very small effect on the pump's head and efficiency but great effect on the pump's cavitation performance. Additionally, inducer test was carried out to investigate the effect of the inducer on the pump in detail, and it was found that the pump reached a critical cavitation number when the inducer head dropped by 55%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.27-32
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• 2010

Performance test of a full-scale turbopump assembly for a 75 ton class liquid rocket engine was carried out at full speed. Model fluid was used as a working medium: liquid nitrogen for the oxidizer pump, water for the fuel pump, and hot air for the turbine. The turbopump was operated stably, satisfying the performance requirements. Head coefficient and flow coefficient of the pumps remained constant at the speed-increasing period. In terms of performance characteristics of pumps and turbine, the results from the turbopump assembly test showed a good agreement with those from the turbopump component tests.

• The Korean Journal of Applied Statistics
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• v.33 no.3
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• pp.281-296
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• 2020

Repeated outcomes from the same subjects are referred to as longitudinal data. Analysis of the data requires different methods unlike cross-sectional data analysis. It is important to model the covariance matrix because the correlation between the repeated outcomes must be considered when estimating the effects of covariates on the mean response. However, the modeling of the covariance matrix is tricky because there are many parameters to be estimated, and the estimated covariance matrix should be positive definite. In this paper, we consider analysis of multivariate longitudinal data via two modeling methodologies for the covariance matrix for multivariate longitudinal data. Both methods describe serial correlations of multivariate longitudinal outcomes using a modified Cholesky decomposition. However, the two methods consider different decompositions to explain the correlation between simultaneous responses. The first method uses enhanced linear covariance models so that the covariance matrix satisfies a positive definiteness condition; in addition, and principal component analysis and maximization-minimization algorithm (MM algorithm) were used to estimate model parameters. The second method considers variance-correlation decomposition and hypersphere decomposition to model covariance matrix. Simulations are used to compare the performance of the two methodologies.

• Polymer Science and Technology
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• v.18 no.5
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• pp.444-449
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.617-618
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• 2008

• 농업기술회보
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• v.51 no.2
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• pp.7-16
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• 2014

올해 쌀 관세화 유예 조치가 끝난다. 1995년부터 2014년까지 20년 동안의 쌀 관세화 유예가 올해로 종료되면서 9월까지 WTO(세계무역기구)에 쌀 관세화 여부에 대한 우리의 입장을 전달해야 한다. 그러나 쌀 관세화에 대한 의견은 팽팽하다. 쌀 관세화 유예조치가 가능하다는 입장과 쌀 관세화를 할 수밖에 없다는 입장이 맞서고 있다. 국회 농림축산식품해양수산위원회는 '쌀 관세화 이후의 쌀 산업전망과 양정 개선' 보고서를 GS&J 인스티튜트를 통해 받으면서 농해수위에서도 썰 관세화 논의를 본격화할 것으로 보이는 만큼 9월까지의 남은 7개월간은 쌀 관세화를 둘러싼 심도 깊은 논의가 예고되고 있다. 이에 본보는 3회에 걸쳐서 썰 관세화의 주요 쟁점 등 쌀 관세화에 대한 찬반양론을 살펴본다.

• Journal of the Korean Chemical Society
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• v.44 no.2
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• pp.170-172
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• 2000

• Proceedings of the CALSEC Conference
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• 1997.11a
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• pp.319-332
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• 1997

. 개발 비용 감소 - 컨설팅 비용 감소 - 쉬운 적합화 방법론 ㆍSlim화 - 업무 기능 체계의 Template화 -업체/업종별 필수 기능 위주 ㆍ개발 기간 축소 - 표준 프로세스 활용 - 특성치를 적용한 방법론개발 ㆍEIS 강조 ㆍFlexible - 표준 프로세스와 기업 특유의 프로세스간의 trade-off 문제 - 기업 전략 및 기반 구조에 따른 해결 ㆍ점진적인 BPR(중략)

• Proceedings of the Costume Culture Conference
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• 2003.12a
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• pp.61-75
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• 2003

청소년기로 대변되는 중ㆍ고등학생은 자기가 평가한 자아상이 아닌 타인이 평가한 자아상을 더 신뢰하는 경향이 있다. 이러한 심리적 불안 또는 신체적 불균형을 해결하기 위하여 의복과 같은 구체적인 외형을 통하여 소속감을 형성하고 심리적 안정과 사회적 인정을 얻고자 한다. 이러한 경향은 자칫 의복에 대한 지나친 관심을 낳기도 한다. 의복에 대한 필요 이상의 관심을 억제시키고, 의복을 통일함으로써 건전한 학교생활을 하도록 하기 위해 교복 착용을 하고 있다. (중략)