• The Journal of Engineering Geology
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• v.19 no.3
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• pp.313-321
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• 2009

The relationship between precipitation and groundwater level and the correlation between the moving average of precipitation and goundwater level were analyzed for the Han river watershed in Korean peninsular. Fourteen regions in the watershed were selected and there were somewhat different patterns of seasonal fluctuation of groundwater level data. The groundwater level data tends to decrease in dry spell and increase in wet spell however the range between maximum and minimum values is quite different for each gauging point. We could have stronger correlation between groundwater level for fractured rock aquifer and the moving average of precipitation than the groundwater level for alluvial aquifer. The critical infiltration, which is the maximum daily infiltration averaged throughout watershed, value is turned out to have the range of 10 to 90 mm. We could have stronger correlation when we consider critical infiltration and modify the original precipitation data than we use original precipitation data. We also could have higher correlation coefficient when we consider snowmelt effect for the watershed that has considerable snow event.

• Journal of the Korean Society for Railway
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• v.19 no.2
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• pp.187-194
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• 2016

It is necessary to determine reliability indexes of existing railway bridges prior to setting up a proper target reliability index that can be used to introduce a reliability based limit state design method to design practice. Reliability is evaluated for a six PSC-I girder railway bridge, which is one of many representative types of double-track railway bridges. The reliability assessment is carried out for an edge girder subjected to bending moment. In the assessment, the flexural resistance and the fixed-load effect were obtained using existing statistical values from previous research on the introduction of limit state design to road bridge design. On the other hand, the live-load effect was determined using statistical values obtained from field measurement for the Joong-ang corridor, on which heavy freight trains are frequently passing. The reliability assessment is performed by AFOSM(Advanced First Order Second Moment method) for the limit state equation, and a sensitivity analysis for the reliability is performed for each factor of the load and resistance effects.

• Journal of Korea Technology Innovation Society
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• v.21 no.4
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• pp.1474-1492
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• 2018

This study empirically analyzes the direct effects of government support for SMEs (project success) and indirect effects (sales growth) focusing on the differences between financially difficult firms (so-called 'zombie' firms) and 'normal' firms. If the zombie firm has a problem in technology development (success of the project) and the economic resilience capability (sales growth), then excluding them from the government's R&D support programs would enhance the overall efficiency of the programs. If not, government R&D could complement the market failure and play a positive role in revitalizing marginal firms. In this study, we collected data about 7,575 firms who participated in seven government R&D programs in 2013 and 2014. As a result of the logistic regression analysis, we did not find evidence that the likelihood of success for zombie firms was lower than that for the normal firms. However, the tendency of sales growth after the project was smaller for the zombie firms than for the normal firms. For zombie firms, we also found that firms that succeeded in the project were more likely to increase sales than those that failed.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.667-669
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• 2004

적응적 웹기반 기법에서 학습자의 반응이나, 탐색 행동의 근본적인 원인이 되는 학습 동기, 지각 등에 대한 판단을 정확히 할 수 없기 때문에, 학습자에게 완전히 적응적인 수업 환경을 조성해 주는 데는 한계가 있다. 이러한 한계를 극복하기 위한 대안으로 학습자간 상호작용이나 협동 학습을 지원하는 웹기반 교수 시스템이 제안되고 있다. 본 논문에서는 웹기반 환경에서 학습자들간의 협동학습을 효과적으로 지원하는 적응형 교수 시스템을 제안한다. 본 시스템은 협동학습 공간에서 주어진 과제를 수행하기 위해 발생되는 학습자들의 대화와 서로간의 상호작용을 분석하여 적절한 조언을 제공함으로서 협동학습이 효과적으로 이루어 질 수 있도록 지원한다.

• Journal of the Korean Geotechnical Society
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• v.17 no.1
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• pp.119-129
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• 2001

연약지반 개량을 위한 시멘트의 사용은 깊은 심도의 점토 지반을 개량하는데 일반적으로 사용되는 기술이 되었다. 시멘트는 지반의 강도를 증가시키고 압축성을 감소시키는 역할을 한다. 시멘트-흙 혼합물의 강도 증가에는 여러 가지 요소가 있는데 이중 대표적인 것은 시멘트량, 흙의 종류, 함수비, 양생시간 등을 들 수 있다. 시멘트 첨가량이 적은 경우, 전단 강도증가는 기본적으로 시멘테이션 효과로 인한 점착력의 증가에 의한 입자들간의 마찰력으로부터 발생한다. 이러한 거동은 과압밀된 흙의 거동과 유사함을 볼 수 있다. 시멘트량이 많은 경우, 강도 증가의 주원인은 입자간의 물리적 결합에 기인하는데 이는 연약한 암석과 비슷한 거동을 한다. 시멘트 고화처리 흙의 응력-변형 거동을 분석하기 위해 한계상태 이론을 적용하였다. 그리고, 토립자간의 시멘테이션 효과를 반영하기 위해 새로운 한계상태 파라메타를 도입하였으며 시멘트 고화처리 점토의 거동을 분석하기 위한 새로운 한계상태 모델을 제시하였다.

• Journal of Technology Innovation
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• v.29 no.2
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• pp.59-85
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• 2021

This study aims to examine whether the characteristics such as a start-up company, possessing a research organization, and benefiting from government R&D programs significantly contributed to the conversion of marginal companies to normal companies, from the viewpoint of technological innovation. The result shows supporting government R&D programs to start-up companies that have become a marginal company positively contributes to the transition to a normal company, centering on the high-tech industry. In addition, it was confirmed that the research organization of marginal companies positively contributed to the transition to a normal company. These results imply that a paradigm shift from the existing industrial policy focusing on restructuring of marginal companies to a selective support policy for marginal companies with a high possibility of transition to normal companies is strongly needed. It is also necessary to strengthen the strategic use of government R&D programs to support the transition of a marginal company to a normal company.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.311-321
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• 2020

In this study, coefficient of variation for the seismic load effect on the segment lining was calculated. The statistical characteristics of the soil property were analyzed for the probability characteristics of domestic soil. In order to calculate the coefficient of variation for the seismic load effect, the MCS technique was applied, and the closed-form equation was applied to calculate the seismic load effect. As a result of calculating the coefficient of variation, the coefficient of variation of the seismic load effect on the weathered soil was analyzed in the range of 0.06~0.15, and the coefficient of variation was judged to be used as basic data for designing the limit state of the shield tunnel on seismic condition.

• Environmental and Resource Economics Review
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• v.6 no.1
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• pp.87-109
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• 1996

본 논문은 조건부가치측정법(CVM)의 적용에 있어 발생할 수 있는 비구분 효과에 대한 검증과 해석을 제시하고 있다. 한강과 한강을 포함한 4대강의 수질증가에 대한 편익을 조건부가치측정법을 이용하여 추정하고 이 과정에서 비구분효과의 발생 원인을 분석하고 있다. 본 논문에서는 비구분효과의 발생 가설로 대체효과 뿐만 아니라 새로운 가설인 순편익효과를 설정하였다. 연구결과는 대체효과 뿐만 아니라 본 논문에서 세운 새로운 가설인 순편익효과가 비구분효과의 원인으로 크게 나타났다. 본 연구 결과로 볼 때 비구분효과가 조건부가치측정법의 자체적 한계라기 보다는 설문의 구성 및 과정상의 문제임을 제시하고 있다.

• Journal of Korea Technology Innovation Society
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• v.2 no.2
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• pp.187-200
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• 1999

전자상거래는 유통업의 형태를 바꿀 정도로 엄청난 기술혁신이지만, 적어도 앞으로 상당기간, 산업적인 성과는 기대이상으로 그렇게 커 보이지 않는다. 기술혁신이 분명 존재하였건만 이 효과를 가로막는 다른 한계들이 있기 때문이다. 바로 이러한 한계가 무엇인가를 보다 집중적으로 분석하고자 한 것이 본고의 목적이다. 이는 전자상거래가 어떻게 하면 성공할 것인가를 살펴보는 것과도 일맥 상통한 것이다. 본고는 종전의 전자상거래 분석 관점과는 달리 유통 전문가적인 시각을 견지한다. 유통 전문가적인 시각이란 유통업적인 관점이고 유통업체를 바탕으로 한 관점이다. 유통업적인 입장을 강조하기 위해 본고는 먼저 점포도 불필요하고 인건비나 관리비를 절감할 수 있다는 전자상거래가 오히려 전통상거래보다 비싸다는 점에서 출발한다. 그리고 매입의 문제, 택배비용의 문제, 거래의 신뢰성 문제, 시장기반의 문제 등이 있다는 점을 지적한다.

• Journal of Labour Economics
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• v.28 no.1
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• pp.135-156
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• 2005

This paper analyzes the distribution and determinants of income of the self-employed, in comparison with salaried workers. Relative to salaried workers, in general, the self-employed tend to have a larger dispersion of income and larger heterogeneity. In this regard, the quantile regression analysis was used, along with a typical OLS regression analysis. According to the empirical findings, the income of the self-employed is larger than that of salaried workers, and this difference is larger for higher income group. The marginal effect of education is larger for higher income groups for both the self-employed and salaried workers, implying the return on education is larger for higher income groups. In contrast, for self-employed women, the marginal effect of education is smaller for higher income groups. Put differently, the return on education in the labor market is larger for salaried workers and self-employed men of high income groups as compared to those of low income groups, whereas the opposite holds for self-employed women.