• The Bulletin of The Korean Astronomical Society
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• v.31 no.2
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• pp.43-43
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• 2006

• Journal of Korean Society of Environmental Engineers
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• v.39 no.4
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• pp.214-219
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• 2017

We analyzed the water quality of first flush and rainfall runoff from a building rooftop, and investigated the removal of suspended solids (SS) in first flush using various media to develop a first flush filtration system. Particle size distribution exhibited most of particles in first flush from the rooftop ranged from 10 to 30 ${\mu}m$. SS concentrations maxed in 10~20 min and decreased afterwards. Dissolved organics and inorganic materials in runoff also showed highest levels in first flush (10 min). Filtration tests using anthracite (AC), polyurethane (PU), polypropylene (PP) showed about 50% of SS removal during the first 10 min operation, but the removal rates dramatically decreased after 20 min of filtration. Based upon the results from rinse and run cycle tests, only AC could achieve nice cycles without distinct decease of SS removal. SS removal rates increased with higher depth of media bed and lower flowrate. The system achieved over 50% of SS removal with a media depth of 30 cm and flowrate < 12 L/min.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.4
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• pp.136-145
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• 2011

For a massive project related to building national industrial complexes on a soft ground applied to PVD after dredging and hydraulic fill, laboratory tests were carried out using undisturbed sample taken from various depth. Piezocone penetration and dissipation tests were carried out to assess horizontal coefficient of consolidation and initial stress in field. The ground consists of upper dredged fill and lower original clay layer having both similar marine clays. It should be, however, considered as multi-layered soft ground having different initial void ratio, initial water content, initial effective stress, and permeability and compressibility with directions. To assess initial stress of those soft layers in which have different stress history related to consolidation, CPTu test results, especially excess pore water pressure, were analyzed. It allows to find out distribution of excess pore water pressure and initial stress inner original clay layer.

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.139-145
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• 2001

One of ways to make high-strength concrete is for the mix contain particles graded down to the finest size : this is achieved by the use of fly ash, silica fume which fills the spaces between the cement particle and between the aggregate and the cement particles. And, the mix needs a sufficient workability. This is achieved by the use of a superplasticizer. This study is to investigate frost resistance of high-strength concrete at early age, with ratio of tensile strength and recovery of compressive strength, when high-strength concrete is placed in cold climates. According to this study, it is necessary to ensure 4 % of air content, 5 kgf/$\textrm{cm}^2$ of tensile strength, at least, for frost resistance of high-strength concrete at early age.

• 한국벤처창업학회:학술대회논문집
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• 2021.04a
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• pp.181-184
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• 2021

본 연구는 국내에 벤처 창업 자금이 많이 제공되나 실제로 스타트업이 투자 유치에 어려움을 겪고 있는 초기투자의 딜레마 문제를 연구하였다. 기술기반 스타트업은 새로운 제품과 서비스를 제공하는 신규 시장을 형성하면서 일자리와 고부가가치를 창출한다는 점에서 국민경제에서 역할이 매우 중요하다. 하지만 주요 선진국에 비해 국내에서는 초기 스타트업이 기술이전 후 창업으로 연계되지 못하는 경우가 많은 실정이다. 특히 최근에 국내 벤처창업 생태계에 정부 자금의 공급이 넘쳐나고 있음에도 불구하고 초기 단계 기업들은 자금 투자의 필요성을 역설하고 다수가 자기자본으로 시작하고 있는 것이 현실이다. 이에 본 연구에서는 국내 창업벤처 및 육성 지원책을 고찰하고, 국내 벤처캐피털 투자현황을 분석하여, 초기 단계 벤처기업에 대한 투자 활성화를 위해 투자 방식의 개선, 투자 주체의 확대, 그리고 투자 유형의 다변화를 제시하고자 하였다. 또한 벤처생태계의 초기투자 활성화를 위한 정책 수립에 필요한 조사와 방안을 제시하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.2
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• pp.284-292
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• 2003

In this paper, we carried out the numerical examination of the initial value setting-up method to extend the range of optimal step parameter in a adaptive system which is controlled by LMS algorithm. For initial value setting-up methods, the general method which select the initial value randomly and the other method which applies the approximate value obtained from the direct method to initial value, were used. And then, we compared to the ranges of step parameter setting, the convergence speeds of mean-square-error, and the stabilities during the convergence process when the initial values were applied to the optimal directivity synthesis problem. According to the numerical simulation results, the initial value setting-up method by means of the direct method provides wider range for the step parameter, more efficient capability for convergence and stability, and more error correction ability than the general method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.9
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• pp.999-1004
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• 2014

In the present paper, the effects of initial crack location on spatial randomness of fatigue crack growth resistance (FCGR) in friction stir welded (FSWed) AA7075-T651 plates were studied. The objective of this study is to characterize the statistical properties of FCGR for three different types of initial crack location (ICL) specimens. In this work, the FCGR coefficients were treated as a spatial random process. It was found that the FCGR coefficients for all initial crack location specimens closely followed a two parameter Weibull distribution. The shape parameter of the Weibull distribution for BM-ICL specimens showed the largest value of 7.50, and that for the WM-ICL specimens showed the smallest value of 2.61. In addition, the autocorrelation functions for all the ICL specimens followed the exponential function.

• Journal of the Korean Institute of Gas
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• v.3 no.1
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• pp.27-32
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• 1999

Chemical processes are highly nonlinear, multivariable systems and have complex structures. However, the controllability evaluation procedures are complicated, and the required information is very often unknown at the early design stage. Therefore, it is necessary to develop a procedure to evaluate and enhance controllability while designing processes and plants. To evaluate controllability in the design stage, it is most efficient to analyze process structure. Relative order can be used as a measure of 'physical closeness' between input and output variable. Structural controllability analysis using relative order is shown to be effective in a case study of heat exchanger network synthesis.

• Defense and Technology
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• no.5 s.279
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• pp.70-81
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• 2002

이동 및 무선의 첨단 정보통신 기술이 발달함에 따라서 미래 전장은 육해공군의 새로운 전군 통합 정보통신체계를 구축하기 위한 사업초기단계에 가장 중요한 소요공학적인 문제를 수반하고 있다. 장차 정보전에 대비하여 소요군이 실시간으로 전쟁을 수행하기 위해서는 필수적으로 전군통합 정보체계를 건설하여야 할 것이며, 특히 정보체계 건설 초기에 체계의 통합성, 상호운용성, 정보보호 및 경제성을 고려하여 구체적 전군통합 정보체계의 요구사항들을 도출 및 파악하고 작성하는 것은 대단히 중요하고 어려운 문제이다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.4
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• pp.266-273
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• 1981

갑자기 작용하는 외압을 받는 직교이방성원통쉘의 동적좌굴을 해석하였다. Donnell-Karnam 형의 비선형방정식을 유도하였으며 쉘의 초기불완전성도 고려하였다. Galerkin의 방법을 사용하여 운동방정식을 구하고 Runge-Kutta 수직해법으로 비선형방정식을 풀었다. 쉘의 직교이방성특성이 처짐-하중 관계식의 비선형성에 미치는 영향을 검토하였으며 동적산출하중의 판별법을 정의하였다. 본 연구의 결과, 직교이방성원통쉘은 쉘의 초기불완전성에 그리 민감하지 않음을 보여주었다.