• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.73-80
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• 2012

It is important to design the optimal shape in the initial process because the influences on the design and construction are large according to the shape and pattern of spatial structures. However, the existing optimal shape designs for spatial structure are performed by the designer's intuition and experiences. Therefore, this study proposes the integrated process using the topology optimization and cellular automata model. First, the initial optimal shapes are obtained by using the topology optimization, and then the spatial truss structural patterns are created through the application of cellular automata rules. Finally, the optimal shapes to satisfy the various design conditions are generated by the structural analysis and size optimization.

• Geotechnical Engineering
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• v.2 no.1
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• pp.55-66
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• 1986

Considering the effects of confining pressure, initial shear stress, cyclic stress ratio and number of loading cycles, cyclic triaxial tests are carried out to clarify the soil dynamic properties such as shear modulus and value of material damping of clay under undrained cyclic loading conditions. The results show that no obvious dependency on initial shear stress and effective confining stress are recognized in the shear modulus and damping ratio plotted versus strain. However, the shear modulus decreases and the damping ratio increases with increasing axial strain. When compared with others, it is also revealed that the shear moduli are distributed within the range curves obtained using empirical equations derived by Marcuson et al. (3) and Kokusho et al. (4), and damping ratios are distributed between the curves obtained by Kokusho et al. (4) and Ishihara et al. (9).

• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.117-133
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• 2002

열차운영계획은 수송수요 산정, 운행노선계획, 열차시간표 작성 기관차 및 인원의 할당 등 광범위한 내용을 포괄하고 있으나, 본 논문에서는 계획의 초기단계에서 결정 가능한 운행노선계획을 대상으로 범위를 설정하였다. 운영목표에 따른 전략은 사용자, 운영자, 사회전체의 입장에서 고려될 수 있는데, 이러한 전략에 의해 운행 될 수 있는 열차운행패턴을 운영비용의 최소화, 통행시간의 최소화. 운영자 수익의 최대화 모형으로 해결하고자 하였다. 2004년 이후에 운행이 예상되는 고속철도/기존철도는 운영계획의 변경이 예상되는 바, 상기의 목표에 따라 열차운영패턴을 작성하여 개발된 효과척도의 적용을 통해 정책적인 적용가능성을 평가하였으며 기존 계획된 철도청의 운영계획과도 아울러 비교, 최적대안을 선정하였다. 본 고에서는 수리계획모형인 비선형정수계획모형(MINLP)으로서 국내 철도망에 부합하는 운영계획을 작성하였으며, 이에 따른 열차-km는 수익최대화 모형, 인-km는 철도청의 열차운영계획이 가장 많은 것으로 나타났다. 인-hour는 수익 최대화 모형과 통행시간 최소화 모형이 가장 적은 것으로 나타났는데, 이는 장거리 노선의 편성이 증가된 것으로 사료된다. 이러한 결과를 산출함에 있어. 어려운 점은 각 구간의 기하급수적 증가, 결정변수의 초기값 선정 등이 있으나, 그동안 연구된 각종 경험적 기법의 적용과 실제 편성 가능한 변수의 적용을 통해 이를 해결하였다. 추후 설정된 모형의 비교에 적합한 효과척도의 개발과 전국적으로 사례구간의 확장 및 모형의 최적대안 선택 시 효과척도의 가중치에 대한 연구가 필요할 것으로 사료된다.

• Journal of the Korean Society for Railway
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• v.15 no.3
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• pp.278-285
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• 2012

The Service Availability (SA) in the viewpoint of passenger is used as the key performance indicator (KPI) of quality of service in Light Rail Transit (LRT) Public-Private Partnerships projects. But there are many disputes on the target value of SA because of the lack of experience in SA. The target value of SA should be set at an early stage of the project to be specified on the system specifications and operation plan. Therefore, this paper developed the quantitative prediction model of SA to set the reasonably achievable target value of SA at an early stage of the LRT project. Also this paper analyzed the relationship and differentiation of SA and Train Punctuality (TP) that is mostly compared with SA.

• 한국벤처창업학회:학술대회논문집
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• 2022.11a
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• pp.167-173
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• 2022

임팩트투자는 재무적인 수익과 더불어 사회에 긍정적인 영향을 만들고자 하는 의도를 가진 기업, 조직, 펀드를 대상으로 하는 투자 방식으로서 사회적 문제를 해결하기 위해 혁신적인 기술과 아이디어를 기잔 소셜벤처 기업에 재무적 지원을 위한 초기단계 투자로서 많은 관심을 받고 있다. 임팩트투자자는 재무적 수익과 사회적 가치추구라는 이중적인 판단 요인 때문에 사회적가치지표(SVI: Social Value Index)를 투자판단에 참고로 활용하고 있으나 투자를 결심하는 판단요인에 있어서는 여전히 개인의 경험과 주관적인 판단에 의존하고 있는 실정이다. 본 연구를 통하여 임팩트투자자가 복합적으로 고려하는 투자판단 요인들에 대한 타당도와 상대적 가중치를 객관화 하고, 재무적 수익과 사회적 가치의 이중적이 가치판단 중에서 어느 쪽을 더 주요하게 고민하는 지에 대하여 분석하였다. 본 연구는 판단분석기법을 활용하였으며 '임팩트투자자의 소셜벤처 투자결정에 대한 종합적인 평가'를 판단문제로 정의하고, 임팩트투자자의 투자의사결정 요인을 도출하기 위하여 투자자로서 재무적 이익과 회수 가능성 판단을 위한 ①초기투자단계에서의 투자의사결정 요인, 사회에 미치는 영향과 파급력, 소셜벤처의 상생과 연대를 위한 ②창업가(팀)의 정치적 기술, 임팩트투자펀드 조성 목적에 부합하는 ③소셜벤처기업의 소셜미션 등 세가지의 분류로 구성하여 연구를 진행하였다.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.239-251
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• 2012

This study aims to seek the policies and the plans for the successful small business start-up through an exploratory study about the factors affecting the success rate of small business start-up. To measure the performance of the start-up business(sales revenue, net profit, and outcome expectancy), the characteristics of founders (experience, psychological characteristics) and the preparation of small business start-up were measured as independent variables and the self-efficacy was measured as a parameter. 427 small business owners were targeted and structured self-administered questionnaires were collected from them. For the data process, a multiple regression analysis by SPSS 18.0 was conducted. The findings demonstrated the experience in the same business, the need for achievement, the risk-taking propensity, the preparation period for business start-up had a significant effect on self-efficacy, and experience of failure and the ratio of net worth had a significant effect on sales revenue and net profit, and the locus of control had a significant effect on outcome expectancy through the self-efficacy, a parameter. It was also noted the self-efficacy of small business owners and the business performance varied depending on the characteristics of them and the preparation process of the business start-up. Based on the those findings, the theoretical and practical implications were discussed and the suggestions about the limits of the study, future policies and studies were made.

• Journal of Chest Surgery
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• v.39 no.8 s.265
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• pp.598-603
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• 2006

Background: High thoracic epidural anesthesia allows awake coronary artery bypass grafting, avoiding the drawbacks of mechanical ventilation and general anesthesia. Materian and Method: From April, 2005 to September, 2005, 12 patients were underwent awake coronary artery bypass grafting using high thoracic epidural anesthesia. There were 1 female and 11 male patients, with a mean age of $66{\pm}6$ years. Off pump coronary artery. bypass grafting was performed through a median sternotomy using arterial grafts. Result: There were no mortality. Pneumothorax was developed during surgery in 8 patients. Five patients required secondary intubation because of pneumothorax (n=3), bowel herniation (n=1), and hemothorax after chest tube insertion (n=1). Postoperative coronary angiography was performed before discharge in all patients and all the grafts were patent. Conclusion: Our intial experience demonstrated the feasibility of awake off-pump coronary artery bypass grafting. Further study is required to define the indications, advantages and limitations of this strategy.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.456-459
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• 2008

We are now in the era of digital convergence with CE products and PC at the center, but product diversification occurs in the same breath. Each device may perform its own functions itself independently, but proportion of the inter-device usage is increasing gradually by concept of a home network and ubiquitous widely prevailed. The consumer's need of inter-device connection will take the dominative position of the market. Therefore, we can easily forecast that diversification of the products may inevitably lead connectivity patterns complicated considering recent market situation and trends. In this paper, we propose the methodology for designing inter-device connectivity which covers issues such like segmenting numerous number of connectivity pattern, and establishing their structure of control. Our methodology also supports the inter-device connection with extensive latitudes and a multi-device simultaneous control. In order to present inter-device connectivity guideline, we define four stages of a user experience - Connection, Configuration, Use, Disconnection. Based on the 4 user experience stages, we suggest a specific connectivity designing guideline for each step.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.418-430
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• 2017

This study examined the process, difficulties and understanding of making teaching materials by investigating the pre-service early childhood teachers' experience of making such materials. The results of the study would help in the design direction and methods of education for pre-service teachers in how to make materials. A total of 30 university students, who took the course of 'Early Childhood Educational Materials and Research Method' in B university, participated in the study. At the exploration stage, the pre-service teachers utilized the teacher guidance of Nuri curriculum, major books, internet materials, and their observation experiences in kindergartens. At the planning stage, they considered chiefly the children's interest and level, explored materials sufficiently, and selected the production method carefully. At the production stage, they performed basic hard work to prevent rework and tended to stick to the basics beyond their initial ambition as the work progressed. The difficulties that they faced, feeling pressured, were making materials based on their imagination without experiencing much from the infants, feeling embarrassed when things did not progress as planned, and feeling a sense of loss when comparing with other friends. Through these difficulties, the importance of precise planning, executing the process thoroughly, and repeatedly checking and reviewing the entire process of making textbooks and materials were realized. In addition, there is a need to search for a better development direction for the effective development of teaching textbooks and materials.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.566-573
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• 2017

The chine of high speed vessels does not only play a role in changing position when planing but also helps balancing the hull. It also has a great influence on resistance performance. However, designing a chine requires a lot of experience because it is influenced by various factors such as displacement, transom shape, draft and width. Such a design is not based on an empirical formula, but the purpose of this study is to provide basic guidelines regarding the shape of chine through calculation. This design was developed using Yacht-one, a commercial design program, and analysis was performed using Star-CCM+, also a commercial analysis program. Analysis of the hull selected in this study was carried out by Dynamic Fluid Body Interaction (DFBI) method. Analysis of the chine was carried out at chine angles of 15, 16, 17, and 19degrees, at a speed of 30knots. The result indicated that the highest trim occurred at 16 degrees among the four chine angles considered, and the highest heave occurred at 15degree. In terms of resistance performance, minimum resistance was observed at 16 degrees. Consequently, for minimum ship resistance, it is necessary to complete calculations in accordance with the chine angles, ${\pm}2$ degrees from the initial chine angle, which should be carried out a the design stage.