• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.262-268
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• 2004

In order to improve the speed of conventional Korean lines, the amendment of speed related regulations is required as the introduction of Korean tilting train. Therefore, an extensive review of UIC leaflets on speed was performed in the areas of tilting train, rolling stocks, operation, civil infrastructures, etc. The review was mainly achieved through the overview of parameters directly related with speed of railway. Moreover, a summary of UIC leaflets on speed and tilting train was provided for a better understanding of speed related UIC CODE. Through the technical overview of UIC CODE, necessary information on the amendment of current Korean speed regulations could be provided.

• Water Engineering Research
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• 제6권3호
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• pp.123-130
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• 2005

A good understanding of the interaction between flow, vegetation, and sediment is required for successful river restoration and sustainable flood management. The purpose of this paper is to provide a summary of available methods to determine flow resistance of natural rivers with vegetation, and discuss the influence of vegetation on erosion and sedimentation processes. Recently, significant advances have been made, but the effects of vegetation on flow and sediment dynamics are still not fully understood. Possible solutions to close the gaps in the current knowledge are suggested, with special focus directed to the determination of the interactive width between main channel and vegetated floodplains, the flow resistance of flexible vegetation with and without leaves, and the flow over submerged vegetation with low water depth.

• 한국정보시스템학회지:정보시스템연구
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• 제30권4호
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• pp.247-275
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• 2021

Purpose This study attempted to predict corporate innovation and business performance using ensemble learning. Design/methodology/approach The ensemble techniques uses weak learning to create robust learning, which combines several weak models to derive improved performance. In this study, XGboost, LightGBM, and Catboost were used among ensemble techniques. It was compared and evaluated with traditional machine learning methods. Findings The summary of the research results is as follows. First, the type of innovation is expanding from technical innovation to non-technical areas. Second, it was confirmed that LightGBM performed best for radical innovation prediction, and XGboost performed best for incremental innovation prediction. Third, Catboost performed best for firm performance prediction. Although there was no significant difference in predictive power between ensemble techniques, we found that comparative analysis was necessary to confirm better prediction performance.

• Journal of Astronomy and Space Sciences
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• 제31권3호
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• pp.247-264
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• 2014

In this paper, a brief but essential development strategy for the lunar orbit determination system is discussed to prepare for the future Korea's lunar missions. Prior to the discussion of this preliminary development strategy, technical models of foreign agencies for the lunar orbit determination system, tracking networks to measure the orbit, and collaborative efforts to verify system performance are reviewed in detail with a short summary of their lunar mission history. Covered foreign agencies are European Space Agency, Japan Aerospace Exploration Agency, Indian Space Research Organization and China National Space Administration. Based on the lessons from their experiences, the preliminary development strategy for Korea's future lunar orbit determination system is discussed with regard to the core technical issues of dynamic modeling, numerical integration, measurement modeling, estimation method, measurement system as well as appropriate data formatting for the interoperability among foreign agencies. Although only the preliminary development strategy has been discussed through this work, the proposed strategy will aid the Korean astronautical society while on the development phase of the future Korea's own lunar orbit determination system. Also, it is expected that further detailed system requirements or technical development strategies could be designed or established based on the current discussions.

• 한국IT서비스학회지
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• 제9권2호
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• pp.129-149
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• 2010

Although many organizations have implemented and used ERP systems for years, industry reports point out that the usage level does not reach their expectation. As a result, they do not enjoy the benefits from the investment into ERP systems. This study attempts to develop a research model and test the model empirically for identifying factors that affect the usage of an ERP system at a public organization. This study has classified potential factors into three groups of technical system characteristics (usability, usefulness), organizational support characteristics (operational support, education and training, evaluation and measurement), and user characteristics (organizational citizenship, self-efficacy). Then, a structural equation model has been established on the basis of previous literature and tested with empirical data. In summary, this study has found that self-efficacy, usefulness, and operational support have an effect on the ERP usage. Self-efficacy is the strongest factor; Usefulness is the second; and the third is operational support. On the contrary to the previous literature, this study has not found a significant effect of organizational citizenship on the usage. The result confirms that an organization can increase the ERP usage by improving the usefulness of an ERP system to some extent. However, to boost the usage further, the result implies that organizations need to strengthen the self-efficacy of their members by reinforcing operational support, providing education and training steadily, and establishing an evaluation mechanism in relation with the ERP usage.

• 경영과학
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• 제17권3호
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• pp.119-129
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• 2000

Design of web site must include community considerations alongside technical design aspects. The main purposes of this study are to identify the community criteria for evaluating web site and to examine how business web sites include the community factors. To identify the evaluation criteria, the author reviewed recent literatures and made a table showing a summary result(see Table 1). appendix shows a sample form NASDAQ(n=82) and KOSDAQ(n=59) which were evaluated. Using the evaluation from with 189 items(Table 3), all sites were visited and review between August 28, 2000 and September 6, 2000. The auther’s evaluations were done from the perspective of community building in business sector. Table 4, summary data on the results of the study, shows that the level of application of the community concept is very low. Among the listed 18 items, only a few items are utilized at more than 50% level. Less than 10% items are Member Profile, Group Segmentation, Backstory, Forum, Chat, Fact-to-face Meeting, and Collaborative Design. the unbalanced utilization due to the lack of community concept in businesses are found. Korea firms are superior to NASDAQ firms in terms of Bulletin Board and FAQ; But Korean firms are inferior and remain at very low level in terms of Member Login, Education Materials, Backstory, Forum, and Integrating Off-line Activities which are core factors of community building.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권1호
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• pp.48-53
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• 2014

In December 2011 and July 2012, two sets of 840MVA hydro-generator of Three Gorges on Yangtze River with Close-loop-self-circulating evaporative cooling (CLSCEC) system were put into commercial operation. In this paper, we make engineering summary of these two generators with CLSCEC system. We also make a comparison between the internal water cooling (IWC) hydro-generator and the CLSCEC hydro-generator used in Three Gorges power plant in fields of their operating characteristics, working performances, technical features, working safety and reliability. In addition, engineering structures, type tests' results and systematic emulating calculation of CLSCEC schemes are analyzed.

• Geomechanics and Engineering
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• 제29권2호
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• pp.145-154
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• 2022

Complex geological conditions have a great influence on the mining of coalbed methane (CBM), which affects the extraction efficiency of CBM. This investigation analyzed the complicated geological conditions in the Liujia CBM block of Fuxin. A geological model of heterogeneities CBM reservoirs was established to study the influence of strike direction of igneous rocks and fault structures on horizontal well layout. Subsequently, the dual-porosity and dual-permeability mathematical model was established, which considers the dynamic changes of porosity and permeability caused by gas adsorption, desorption, pressure change. The results show that the production curve is in good agreement with the actual by considering gas seepage in matrix pores in the model. Complicated geological structures affect the pressure expansion of horizontal wells, especially, the closer to the fault structure, the more significant the effect, the slower the pressure drop, and the smaller the desorption area. When the wellbore extends to the fault, the pressure expansion is blocked by the fault and the productivity is reduced. In the study area, the optimal distance to the fault is 70 m. When the horizontal wellbore is perpendicular to the direction of coal seam igneous rock, the productivity is higher than that of parallel igneous rock, and the horizontal well bore should be perpendicular to the cleat direction. However, the well length is limited due to the dense distribution of igneous rocks in the Liujia CBM block. Therefore, the horizontal well pumping in the study area should be arranged along the direction of igneous rock and parallel plane cleats. It is found that the larger the area surrounded by igneous rock, the more favorable the productivity. In summary, the reasonable layout of horizontal wells should make full use of the advantages of igneous rock, faults and other complex geological conditions to achieve the goal of high and stable production.

• 한국지구과학회지
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• 제29권4호
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• pp.341-351
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• 2008

본 연구의 목적은 8학년 학생들의 탐구보고서에 제시되어 있는 과학방법의 특징을 조사하려는 것이다. 문헌 연구로부터 과학의 본성을 고려하여 '과학방법과 정보출처 분석'이라는 분석들을 개발하였으며, 이를 사용하여 학생들의 '방법설계', '데이터분석', 정보출처'를 분석하였다. 그리고 분석 결과를 질문수준과 비교하여 '과학방법'이 질문수준의 영향을 받는지 조사하였다. 또한, 학생들이 탐구 활동을 하면서 '과학방법'을 설계할 때 겪는 어려움을 알기 위해 실시한 설문지의 응답을 분석하였다. 결과는 첫째, '방법설계'는 자문과 활동이 있으며, 활동은 실험, 상관연구, 관찰을 말한다. 그 중에서 학생들은 '자문'으로 설계하는 경우가 많았다. 활동을 설계한 경우, 대부분의 학생들은 '실험'을 설계하였다. 둘째, '데이터분석'은 요약, 표, 도표, 그래프 등이 있으며, 학생들은 '요약' 형태로 그들의 데이터를 분석하는 경우가 많았다. 그리고 '요약'은 '단순요약'과 '관계진술'로 구분되었다. 셋째, '정보출처'는 컴퓨터, 도서관, 전문가 상담이 있으며, 대부분의 학생은 정보를 '컴퓨터'에서 구하였다. 넷째, 학생들의 '방법설계'와 '요약'은 질문수준의 영향을 받는 것으로 나타났다. 다섯째. 일부 학생들은 정보가 부족하거나 부정확할 뿐 아니라 정보에 제시된 전문 용어가 어려워 '방법설계'가 어렵다고 하였다.

• 디지털융복합연구
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• 제20권2호
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• pp.407-413
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• 2022

본 연구는 초기 연구를 통해 제작하고 개발한 'COVID-19 SABER' VR 게임의 기술적, 내용적 구성 요소가 사용자의 시각적 몰입감 향상에 영향을 미치는지 알아보기 위해 사용자 체험과 설문을 통해 실증 분석을 진행하였다. 그 결과 먼저, 기술적 구성 요소의 해상도, 시야각, 이펙트, 디자인 품질에 관한 가설은 채택되었고, 프레임 레이트, 조명의 밝기에 관한 가설은 기각되었다. 다음으로, 내용적 구성 요소의 가설은 배경, 연출, 색상과 질감, 흥미와 재미에 관한 가설은 채택되었고, 스토리텔링에 관한 가설은 기각되었다. 정리하면, VR 게임의 시각적 몰입감 향상을 위해서는 기술적 구성 요소의 해상도, 시야각, 이펙트, 디자인 품질과, 내용적 구성 요소의 배경, 연출, 색상과 질감, 흥미와 재미를 중심으로 설계하고 제작해야 한다는 결과를 도출하였다. 본 연구 결과는 향후 사용자의 시각적 몰입을 유도하고 향상할 수 있는 VR 게임의 제작 및 개발 분야에 기초 자료가 될 것으로 기대한다.