• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.3
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• pp.114-120
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• 2000

In this study a computer program considering initial imperfection of wall of axisymmetric reinforced concrete shell which show plastic deformation by large external loading is developed. initial imperfection of wall of axisymmetric reinforced concrete shell is assumed as sinusoidal curve expressed as {{{{ {W }_{i } }}}}={{{{ {W}_{0 } }}}}sin (n$\pi$y/$\ell$)y. The developed program is applied to the analysis of the dynamic response of axisymmetric reinforced concrete shell when the wall has initial imperfection. The initial imperfection of 0.0 -5.0, and 5cm and steel ratio 0.3, and 5% are tested for numerical examples. The effects of the wall initial imperfection and steel ratio on the dynamic response of the axisymmetric reinforced concrete shell are analysed, It is shown that the direction of the initial imperfection is very important factors for determining the dynamic response.

• The Journal of Small Business Innovation
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• v.19 no.4
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• pp.41-52
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• 2016

This paper examines the effect of unique underwriter lockup on the initial returns of an initial public offering (IPO) in the Korean Securities Dealers Automated Quotation (KOSDAQ). Underwriter lockup induces underwriters to underprice IPOs and stabilize aftermarket prices. The inducement is explored with respects to the mixtures of distributions of the initial returns consistent with underpricing and stabilization. Whether the inducement is meaningful when other factors are controlled is also explored. These explorations provide evidence that underwriter lockup leads to more positive average initial returns in the three aftermarket months.

• The KIPS Transactions:PartB
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• v.11B no.7 s.96
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• pp.867-874
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• 2004

K-Means algorithm is a non-hierarchical (plat) and reassignment techniques and iterates algorithm steps on the basis of K cluster centroids until the clustering results converge into K clusters. In its nature, K-Means algorithm has characteristics which make different results depending on the initial and new centroids. In this paper, we propose the modified K-Means algorithm which improves the initial and new centroids decision methodologies. By evaluating the performance of two algorithms using the 16 weighting scheme of SMART system, the modified algorithm showed $20{\%}$ better results on recall and F-measure than those of K-Means algorithm, and the document clustering results are quite improved.

• Journal of the Korean Geophysical Society
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• v.4 no.1
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• pp.35-46
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• 2001

한반도 중부에 위치한 대전 지진관측소(TJN) 하부의 세부 지각구조를 밝혀내기 위하여 수신함수를 이용한 선형화된 역산(linearized inversion) 방법을 적용하였다. 본 방법의 비단일해(nonuniqueness)와 초기 모델 의존성의 문제를 해결하기 위해 근사 초기 속도 모델로부터 72개의 서로 다른 초기 모델을 구하여 역산을 수행한 후 결과모델들의 평균 속도 모델을 제시하는 방법을 사용하였다. 역산 결과 총 72개의 모델 중 뚜렷한 지각-맨틀 경계를 보이는 43개의 모델만이 조건에 만족하는 결과를 나타내었다. 모든 모델에서 속도 구조는 전체적으로 깊이에 따라 속도의 불연속면이나 급격한 증가없이 연속적인 변화를 하며, 모호면의 깊이는 30～32.5 km의 범위로 나타났다. 평균적인 하부 지각의 속도는 6.5 km/s, 상부 맨틀의 속도는 7.8 km/s로 뚜렷한 속도 변화를 보였다. 결과 모델 군은 중부지각(mid-crust)에서의 속도를 기준으로 약한 저속도층을 나타내는 군과 상대적으로 일정한 속도를 가지는 군으로 구분되었다. 단지 지진파형의 비교만으로 두 모델군 중 합당한 모델군의 선택은 불가능하였다. 따라서 수신 함수를 이용하여 연구 지역의 신뢰할 만한 지각 구조를 구하기 위해서는 그 지역에 대한 지질학적, 지구물리학적 추가정보와의 동반 해석이 요구된다.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.178-186
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• 2011

This study was conducted to investigate runoff characteristics of non-point pollutant sources in an agricultural area watershed in Boeun area, Chungbuk Province. The monitoring site represented 1.56 $km^2$, about 44.4% of which was covered with paddy fields. The monitoring was conducted for six events in a period of 5 month. Event Mean Concentration (EMC) and Site Mean Concentration (SMC) of suspended solids (SS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (T-N) and total phosphorus (T-P) were calculated using the results of the water quality parameters. A comparison between arithmetic mean concentration and EMC revealed that nearly all EMCs were higher than the corresponding arithmetic mean concentrations. First-flushing effects were exhibited for SS, BOD, and T-P, with relatively high concentrations in early-stage storm events.

• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.251-253
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• 1999

• 한국벤처창업학회:학술대회논문집
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• 2016.04a
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• pp.48-50
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• 2016

본 연구는 벤처캐피탈에 대한 정부의 간접출자가 창업초기단계 기업에 대한 투자를 장려하는지에 대해 논한다. 벤처캐피탈의 의사결정이 합리적 투자자의 관점을 취한다고 가정하고 정부의 자금투여가 이에 영향을 미치는 원리를 불확실성 완화효과, 정책유도 효과, 투자금의 규모의 경제효과, 정보비대칭성 완화효과, 자본비용 완화효과로 분해하여 이론적 고찰을 한다. 이론적 논의를 종합하여, 본 논문은 다음의 주장을 한다. 첫 째, 정부출자금의 규모가 벤처캐피탈의 창업초기단계 기업에 대한 투자를 증가시키는 효과를 가질 것이다. 둘 째, 창업초기단계에 대한 투자지침을 명시한 출자금을 유치한 벤처캐피탈의 창업초기단계 투자가 그러한 투자지침을 갖지 않는 출자금을 유치한 벤처캐피탈에 비해 클 것이다. 셋 째, 정부출자금의 창업초기단계 기업의 투자에 대한 규모효과는 일정 수준 이상이 되면 감소하여 역U의 형태를 보일 것이다. 본 연구는 2010년부터 2013년 사이 투자활동을 벌인 한국의 105개 벤처캐피탈사의 출자금 구성과 투자 내역자료를 활용하여 상기 주장의 유효성을 실증 조사하였다. 다중회귀분석을 포함한 다양한 통계적 검정의 결과 세 가지 주장을 모두 지지하는 일관된 결론을 얻었다. 본 연구는 벤처캐피탈의 투자행태 및 정책개입의 효과와 메커니즘에 대한 새로운 설명을 제시한다는 이론적 의의와 이에 대한 실증근거의 제시를 통해 벤처기업 및 벤처캐피탈 정책의 효과와 방향성에 대한 재검토의 기회를 제공한다는 실무적 의의를 갖는다.

• Journal of Conservation Science
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• v.27 no.2
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• pp.135-144
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• 2011

When metal artifacts have to undergo conservation treatment, the person in charge of the treatment selects and uses various coating mixtures based on his judgment regarding their condition, material, or environment. Since the kinds of coating mixtures or solvents make a difference in the set time of cyanoacrylate adhesives, they have something to do with the efficiency of the conservation treatment. This study examines the effects and causes that affect the set time of cyanoacrylate adhesives according to the kinds of coating mixtures and solvents and suggests ways to increase the set time. As a result, it is thought that as the surface roughness gets flatter, the wettability of adhesive is improved further, which increases the set time. Moreover, the C-F binding of V-Flon, C-O-C absorption peak, molecular weight of the coating mixtures, and glass transition temperature (Tg) were the factors that significantly affected the set time. According to the result of measuring the set time based on the result of superficial and chemical analysis, relative difference was shown according to the kind and viscosity of adhesive, but all the adhesives indicated the following order of the set time: V-Flon > Paraloid B-72 (in xylene) > Paraloid NAD-10 > Paraloid B-72 (in acetone).

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.10 no.6
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• pp.47-57
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• 2015

This study examines whether successful stand-alone firms have more difficulties than the successful firms affiliated to business groups in external financing. The easiness of external financing is measured by investment-cashflow multiple. Controlling the effects on the multiple of the past business performances and the expectation of future business performances, we investigate how the ownership type affects the multiple. The empirical results show that, when cashflows are positive, the stand-alone firms exhibit higher investment-cashflow mupltiples. When cashflows are negative, however, the opposite is true, even though the statistical significance of the result is rather low. These results do not support the general idea that stand-alone firms must have more disadvantage than subsidiary firms in raising funds from outside. If member firms of business groups have no big trouble financing externally, then the above results imply that stand-alone firms do not either identify external financing as a major difficulty in running business. Thus, if the government seeks to formulate the selective policies supporting only the promising start-ups, instead of the general policies benefiting random start-ups, then the start-up financing policy should have a lower priority.

• International Journal of Highway Engineering
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• v.6 no.2 s.20
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• pp.47-59
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• 2004

The temperature variation of concrete pavement at early-age significantly affects the initiation and propagation of its early-age cracks. This implies that the measurement and analysis of early age temperature trend are necessary to examine the causes of early age cracks in the concrete pavement. In this study, it is investigated how the early age temperature trend in concrete pavement affects the random crack initiation and behaviors of saw-cut joints using the actual construction site which is located at the KHC test road. During 72 hours after placing the concrete pavement, the ambient air temperature and temperatures at the top, middle, and bottom in concrete pavement were measured and the random crack initiation in concrete slabs and early age behaviors in the joints were surveyed. The investigation results indicate that the first random crack was initiated at one of the slabs placed in the early morning which have higher temperature changes during early 72 hours. The movement of slab was influenced by the early-age crack in the joint. It suggested that the different occurrence time of the cracks in the joint had an influence on the behavior of the cracks. Besides, the slab constructed In the morning had higher possibility of crack initiation than that in the afternoon. The rarely occurred cracks had bigger gap than other cracks.