• Journal of Korea Port Economic Association
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• v.32 no.4
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• pp.165-182
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• 2016

This study examines the competitiveness and cooperativeness among the container ports in East Asia by analyzing their monthly dynamics in eight years (2008-2015). Time series data on container throughput divided into origin and destination (O/D), such as the top six Chinese ports and the transshipment (T/S) ports such as Hong Kong, Busan, and Singapore, are computed with two methods based on the Vector Error Correction Model (VECM). The first Granger causality test results show that Busan T/S has significant bilateral relations with three Chinese O/D ports; and significant unidirectional relations with three other O/D ports. Shenzhen port has significant bilateral relations with Singapore, and has a significant unidirectional relation with Hong Kong port. Co-integrating test results showed that Busan holds negative co-integration with all Chinese O/D ports. Impulse response function (IRF) results show an opposite direction between paired ports. The ratios of the impulse from T/S ports are significantly high to one another in the short-run, but its power declines as time passes. The ratio of the impulse from the Chinese ports to T/S ports is less significant in the short-run period, however, it becomes more significant as time passes. The significance of most shocks was high in the second period, but was diluted after the sixth period.

• Journal of Environmental Impact Assessment
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• v.22 no.6
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• pp.591-607
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• 2013

The objectives of the study were to evaluate the aquatic environment of an urban stream using various ecological parameters of biological biomarkers, physical habitat quality and chemical water quality and to develop a "Multimetric Eco-Model" ($M_m$-E Model) for the ecosystem evaluations. For the applications of the $M_m$-E model, three zones including the control zone ($C_Z$) of headwaters, transition zone ($T_Z$) of mid-stream and the impacted zone ($I_Z$) of downstream were designated and analyzed the seasonal variations of the model values. The biomarkers of DNA, based on the comet assay approach of single-cell gel electrophoresis (SCGE), were analyzed using the blood samples of Zacco platypus as a target species, and the parameters were used tail moment, tail DNA(%) and tail length (${\mu}m$) in the bioassay. The damages of DNA were evident in the impacted zone, but not in the control zone. The condition factor ($C_F$) as key indicators of the population evaluation indicator was analyzed along with the weight-length relation and individual abnormality. The four metrics of Qualitative Habitat Evaluation Index (QHEI) were added for the evaluations of physical habitat. In addition, the parameters of chemical water quality were used as eutrophic indicators of nitrogen (N) and phosphorus (P), chemical oxygen demand (COD) and conductivity. Overall, our results suggested that attributes of biomarkers and bioindicators in the impacted zone ($I_Z$) had sensitive response largely to the chemical stress (eutrophic indicators) and also partially to physical habitat quality, compared to the those in the control zone.

• The Journal of the Korea Contents Association
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• v.8 no.7
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• pp.201-207
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• 2008

The bankruptcy possibility of apartment construction firms has been incresed because of the environment of current apartment construction industry. This paper analyzes the efficiency of apartment construction firms using DEA model. We evaluate the CCR, BCC efficiency and RTS of 25 apartment construction firms. We also suggest the apartment construction firms which can be benchmarked based on analyzed information. The result shows that four enterprises whose values of CCR efficiency are 1, and ten enterprises whose values of BCC efficiency are 1. RTS indicates IRS of 21 firms and CRS of 4 firms.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1737-1740
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• 2006

본 연구에서는 1차원 수치모형을 이용하여 댐 여수로에서 발생하는 흐름을 해석하였다. 본 연구에서 사용한 1차원 수치모형은 매우 복잡한 지형에 적용이 가능하며, 상류가 사류가 동시에 발생하거나 도수가 발생하는 흐름도 해석할 수 있는 모형이다. 이 모형은 해석해를 가지는 도수의 경우에 적용하여 검증된 바 있으며, 자연하천의 보에서 발생하는 불연속 흐름에 대해서도 적용된 바 있다. 또한 매우 불규칙한 자연하천에서 발생하는 흐름도 효과적으로 모의할 수 있다. 본 연구에서는 댐 여수로 흐름 해석을 평가하기 위해 단순화된 하도에서 발생하는 불연속 흐름에 대해 이론적인 해와 비교하였다. 또한 댐 수리모형 결과에 수치모형을 적용하여 빈도별로 발생하는 흐름을 해석하였다. 해석결과 여수로에서 발생하는 매우 작은 수심을 정확하게 모의하였으며, 여수로 직하류부에서 발생하는 도수의 발생위치, 발생 전후의 수위도 잘 모의하는 것으로 나타났다. 또한 여수로 및 도수 전후에 발생하는 유속도 정확하게 모의하는 것으로 나타났다. 또한 본 연구에서는 1차원 수치모형을 여수로 뿐만아니라 댐 상류 하천, 저수부, 여수로 접근수로, 여수로, 도수, 하류하천등으로 구성되는 전 구간의 흐름을 동시에 모의하기 적용하였다. 적용 결과 댐 저수지 상류 하천과 저수지, 저수지와 접근수로, 접근 수로와 여수로, 여수로와 도수, 도수 발생 후와 하류하천 등에서 복잡하게 형성되는 흐름을 동시에 잘 모의하는 것으로 나타났다. 본 연구에서 사용한 1차원 수치모형을 이용하면 댐 여수로나 저수지, 연계되어 있는 상하류 하천에서의 흐름을 동시에 해석할 수 있기 때문에 향후 수리모형실험과 연계하여 댐 설계에 효율적으로 사용될 수 있을 것으로 전망된다.지는 것으로 평가되었다. 그러나 본 연구결과를 통하여 투수성 포장과 지하수에 관련된 매개변수의 집적과 분석결과는 현장기술 적용 시 매개변수의 유용한 선택과 도시유역의 물 순환 건전화 대안기술 적용에 효과적인 방법론을 제시할 수 있을 것으로 사료된다.첨두홍수량을 저류하기 위해서 상대적으로 넓은 저류면적이 필요한 것으로 나타난다. 대등한 수위감소값의 홍수저감효과를 발휘하기 위해서 본 연구에서는 On-Line 저류지 면적은 Off-Line 저류지에 비 두배 이상이 필요한 것으로 보여졌다.들에 관한 정보는 종종 현장관측에서 조차 무시되는 경우가 많다. 이에 본 연구에서는 수질모형의 매개변수 중 특히 수리특성에 관련된 매개변수들이 수질에 미치는 영향을 파악하는 것을 목적으로 하고 있다. 이를 위해 적용된 수질모형은 QualKo를 사용하였으며, 대상 하천은 낙동강 본류 경남구간 시점 부근인 회천 합류 전부터 낙동강 본류 경남구간 종점 부근인 밀양강 합류 전까지의 경남 오염총량관리 기본계획 시 구축된 모형 매개변수를 바탕으로 분석을 수행하였다. 일차오차분석을 이용하여 수리매개변수와 수질매개변수의 수질항목별 상대적 기여도를 파악해 본 결과, 수리매개변수는 DO, BOD, 유기질소, 유기인 모든 항목에 일정 정도의 상대적 기여도를 가지고 있는 것을 알 수 있었다. 이로부터 수질 모형의 적용 시 수리 매개변수 또한 수질 매개변수의 추정 시와 같이 보다 세심한 주의를 기울여 추정할 필요가 있을 것으로 판단된다.변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기 위한 연구가 필요할 것이다.게 이루어질 수 있을 것으로 기대된다.는 초과수익률이 상승하지만, 이후로는 감소하므로, 반전거래전략을 활용하는 경우 주식투자기간

• Journal of Korean Society of Transportation
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• v.21 no.3
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• pp.15-22
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• 2003

In general, the linear regression model has been used to estimate trip generation in the travel demand forecasting procedure. However, the model suffers from several methodological limitations. First, trips as a dependent variable with non-negative integer show discrete distribution but the model assumes that the dependent variable is continuously distributed between -$\infty$ and +$\infty$. Second, the model may produce negative estimates. Third, even if estimated trips are within the valid range, the model offers only forecasted trips without discrete probability distribution of them. To overcome these limitations, a poisson model with a assumption of equidispersion has frequently been used to analyze count data such as trip frequencies. However, if the variance of data is greater than the mean. the poisson model tends to underestimate errors, resulting in unreliable estimates. Using overdispersion test, this study proved that the poisson model is not appropriate and by using Vuong test, zero inflated negative binomial model is optimal. Model reliability was checked by likelihood test and the accuracy of model by Theil inequality coefficient as well. Finally, marginal effect of the change of socio-demographic characteristics of households on trips was analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7690-7697
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• 2015

This study is to reveal structural causal relationship of individual factors influencing association member's substantive payment in the economic view which is a critical factor of project implementation and identify its influence through simulation and actual proof analysis. As the results of analysis, the first, association member's substantive payment is decided to allow for the difference between special price for association members and general price and the profit arising between the time of approval of disposal plan and moving in. The second, on analysis of sensitivity of individual factors influencing association member's substantive payment, floor area ratio applied to project has the biggest influence. Association member's payment is also greatly influenced by the subject of cost allocation for establishing infrastructure in project area. The third, this study set up a structure model based on causal relationship among the factors deciding association member's payment and empirically examined influence and path of influence which the individual factors exercise. The result indicates that control elements and regional characteristic elements influence association member's payment through the medium of plan elements.

• Journal of Korea Port Economic Association
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• v.38 no.2
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• pp.31-47
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• 2022

The purpose of this study is to develop a reliable tool that can classify and measure detailed indicators related to the performance of ESG implementation in the country and verify their applicability. Based on World Bank's data as input data, 67 types of ESG-related detailed indicators measured in a total of 239 countries were tested to derive an optimal model that could group detailed indicators into three categories: environment, society, and governance. As a result of the analysis, it was confirmed that a total of 10 detailed indicators had a statistically significant relationship with the country's ESG performance. In addition, the detailed indicators showed a positive correlation with the primary latent variables E, S, and G, and showed a high overall index in the suitability of the model to secure the validity and reliability of variable input. As a result, this study confirmed that several detailed performance indicators constituting ESG can be classified as latent variables, and it can be said that clear criteria for the selection method and input validity of variables were presented.

• Proceedings of the Korean System Dynamics Society
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• 2002.11a
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• pp.33-56
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• 2002

오늘날 급격한 경영환경의 변화와 공급 주도에서 수요 중심으로의 시장환경 변화, 그리고 고객 욕구의 다양화, 복잡화로 인하여 치열해진 경쟁상황 속에서 많은 기업이 그들의 생존전략으로 고객만족경영에 주력하고 있다. 특히, 이동통신서비스 산업은 다른 산업에 비해 상표전환비율이 높고 이미 시장이 포화되어 경쟁이 치열하기 때문에 이동통신 사업자의 고객 만족도 제고를 통한 기존 고객유지 및 신규 고객 확보 노력은 기업 생존의 필수적인 전략이라 할 수 있다. 그러나 고객만족에 영향을 미치는 요소나 변수는 너무나 다양하고 복잡하여 어느 특정 변수 하나만을 독립적으로 분리할 수 없으며 더군다나 고객만족의 결과가 단기에 나타나는지 아니면 장기에 걸쳐 나타나는지 또는 직접적인지 아니면 간접적인지에 따라 고객만족이 지니는 의미와 기업 전략에 미치는 영향은 판이하게 달라질 것이지만 이에 대한 해답을 줄 수 있는 연구는 아직 미흡한 실정이다. 이에 따라 본 연구는 이동통신 시장에서의 고객만족과 상표전환 및 기업성과간의 동태적 특성을 복잡한 문제를 이해하는데 용이한 시스템 다이내믹스 방법론에 근거한 인과 모델을 이용하여 분석하여 보았으며 정부의 시장점유율 제한규제의 효과와 이에 따른 시장 변화를 현 이동통신 3사간의 경쟁 모형을 시뮬레이션하여 살펴보았다.

• The Korean Journal of Applied Statistics
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• v.3 no.2
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• pp.39-53
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• 1990

For the present study two sets of artificially unbalanced data of being $n_{ij}>0$ and ${n_{1j}}{/geq}0$ were used. The Hypotheses that are commonly used in ANOVA were examined by computing the sums of squares associated with the hypotheses under various postulated models, using Searle's R($\mid$)-notation.

• Journal of the Korean Data and Information Science Society
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• v.25 no.2
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• pp.365-371
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• 2014

Association rule of the well-studied techniques in data mining is the exploratory data analysis for understanding the relevance among the items in a huge database. This method has been used to find the relationship between each set of items based on the interestingness measures such as support, confidence, lift, similarity measures, etc. By typical association rule technique, we generate association rule that satisfy minimum support and confidence values. Support and confidence are the most frequently used, but they have the drawback that they can not determine the direction of the association because they have always positive values. In this paper, we compared support, basic confidence, and three kinds of confidence measures useful for classification model building to overcome this problem. The result confirmed that the causal confirmed confidence was the best confidence in view of the association mining because it showed more precisely the direction of association.