• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.147-156
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• 2009

We present a methodology for modeling and solving the transit frequency design problem with variable demand. The problem is described as a bi-level model based on a non-cooperative Stackelberg game. The upper-level operator problem is formulated as a non-linear optimization model to minimize net cost, which includes operating cost, travel cost and revenue, with fleet size and frequency constraints. The lower-level user problem is formulated as a capacity-constrained stochastic user equilibrium assignment model with variable demand, considering transfer delay between transit lines. An efficient algorithm is also presented for solving the proposed model. The upper-level model is solved by a gradient projection method, and the lower-level model is solved by an existing iterative balancing method. An application of the proposed model and algorithm is presented using a small test network. The results of this application show that the proposed algorithm converges well to an optimal point. The methodology of this study is expected to contribute to form a theoretical basis for diagnosing the problems of current transit systems and for improving its operational efficiency to increase the demand as well as the level of service.

• Proceedings of the Korean Vacuum Society Conference
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• 2008.02a
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• pp.137-137
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• 2008

• Journal of Korean Society of Transportation
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• v.19 no.1
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• pp.89-99
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• 2001

The conventional studies on equilibrium network design problem(ENDP) with fixed travel demand models assume that the future OD travel demand might not be changed even if the structure and the capacity of the network are improved. But this fixed demand assumption may loose its validity in the long-range network design because OD travel demand actually shifts with the network service level. Thus, it is desirable to involve the variable travel demand which is determined endogenously in the model in the optimal network design. In this paper a hi-level model formulation and solution procedure for ENDP with variable travel demand are presented. Firstly It is considered how to measure the net user benefits to be derived from the improved in link capacities, and the equilibrium network design problem considered here is to maximize the increase of net user benefit which results from a set of lift capacity enhancements within the budget constraints, while the OD travel demands and link travel times are obtained by solving the lower level network equilibrium problem with variable demand. And secondly sensitivity analysis is carried out to find the links to which the network equilibrium flow pattern is the most sensitive. Finally numerical example with simple network is carried out to test the validity of the model.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.103-117
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• 1995

A design-oriented method for analysis of the structural damage due to ship collisions is developed by using the idealized structural unit method(ISUM). The method takes into account yielding, crushing, rupture, the coupling effects between local and global failure of the structure, the influence of strain-rate sensitivity and the gap/contact conditions. The method is verified by a comparison of experimetal and numerical results obtained from test models of double-skin plated structures in collision/grounding situations with the present solutions. As an illustrative example, the method has been used for analyses of a side collision of a double-hull tanker. Several factors affecting ship collision response. namely the collision speed and the scantlings/arrangements of strength members, are discussed.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.716-716
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• 2012

최근 항만구조물을 설계함에 있어 대수심 및 고파랑 지역에 설치되는 외곽시설의 상당수는 직립식 케이슨 혼성제 단면을 채택하고 있다. 이는 상대적으로 수심이 깊고, 설계파와 같은 외력 조건이 크기 때문에 경사제에 비하여 경제성 및 시공성이 유리하기 때문으로 판단된다. 그렇지만 아직까지 소규모 항만 및 어항시설에 있어 경사제를 채택하고 있다. 본 연구에서는 이와 같은 경사식 구조물을 설계함에 있어 월파에 의한 방파제 배후 경사면에 피복된 피복재의 안정성을 검토하며, 실험사례를 통하여 최적 설계안 및 설계방향을 제시하고자 한다. 경사식 구조물 배후 사면 피복재의 안정 중량에 대해서는 우리나라의 항만 구조물의 설계기준(항만 및 어항설계기준, 2005) 뿐만 아니라 국외의 설계기준(CEM, Coastal engineering manual, 2005 등)에서도 아직까지 설계법을 제시하고 있지 않고 있다. 본 연구에서 수행한 단면 수리모형실험에서는 1/50의 실험축척을 적용하여 대상 외곽 구조물에 대하여 수리특성과 안정성을 검토하였다. 특히 경사제 배후의 안정성 확보를 위하려 동일 구간에 대하여 설계파 조건 등을 중심으로 총 9개의 실험안을 설정하여 안정성을 검토하였다. 아래 그림은 이중 초기 설계안과 최종적으로 제안된 제시안에 대한 완성모형, 실험장면 및 결과이다. 일반적으로 접안시설과 외곽시설이 어느 정도 이격되어 있어 적정량의 월파를 허용할 수 있는 경우 상치콘크리트의 형상 및 마루높이을 변경하여 월파의 낙하 및 도달거리를 배후면의 안정성을 확보할 수 있을 정도로 유도함으로써 안정적인 구조물 설계가 가능할 것으로 판단된다.

• Korean Journal of Social Welfare
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• v.59 no.2
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• pp.89-114
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• 2007

The purposes of this study were : (1) to find out subjective well-being structural model of people with disabilities, (2) to compare the female's subjective well-being structural model with male's. Based on previous researches related to subjective well-being of non-disabled, I applied a integrative model of bottom-up and top-down theories to subjective well-being of people with disabilities. Data were gathered from 497 persons with disabilities(253 males and 244 females) in Korea. This research shows that the female's level of life satisfaction is not different to male's. In female group, the objective life conditions(the level of education, family income, and to have jobs or not) and self esteems are important variables in subjective well-being structural equation model. In male group, on the other side, recognition about social support level is important variable. Various theoretical and practical implications for social work practice were discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.653-656
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• 2007

1998년 European Commission에서 권고한 이래 LRIC 모형은 미국 및 유럽 각국의 규제기관 (National Regulatory Authorities ; NRA)에서 상호접속규제를 시행하는데 사용되는 주요 수단이다. 2004년 영국의 이동전화 착신서비스에 대한 보고서에서 영국의 Ofcom은 LRIC를 2G방식의 이동전화 착신서비스 제공에 따른 원가산정 방법으로 채택하고 있다. 그러나 기존 2G 사업자들이 3G시장에 참여함에 따라 2G 음성통화가 3G로의 전이가능성이 제기되어 3G 서비스제공에 따른 2G 접속료 시장의 충격을 완화하고자 LRIC모형에 3G서비스를 추가하게 되었다. 이동망 원가모형의 기본 구조는 크게 다음과 같은 4개의 모듈로 구성되는데, 이중에서 사업 자간 문제제기가 많고 이견이 많았던 Network모듈과 이동망 모형의 선행모듈인 Input 모듈에서 제기된 이슈사향을 살펴보고, 국내 이동망 LRIC 모듈 개발시의 시사점을 도출하고자 한다.

• Journal of Korea Water Resources Association
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• v.49 no.9
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• pp.789-798
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• 2016

Frequent algal blooms at major river systems in Korea have been serious social and environmental problems. Especially, the appearance of cyanobacteria with toxic materials is a threat to secure a safe drinking water. In order to model the behaviour of cyanobacteria cell number, an exclusive causality analysis using prewhitening technique was introduced to delineate effective parameters to predict the cell numbers of cyanobacteria in Seungchon Weir and Juksan Weir along Youngsan river system. Both input and output transfer function models were obtained to explain temporal variation of cyanobacteria cell number. A threshold behaviour of water temperature was implemented into the model development to consider winter characteristic of cyanobacteria. The implementation of water temperature threshold into the model structure improves the predictability in simulation. Even though the input output transfer model cannot completely explained all blooms of cyanobacteria, the simple structure of model provide a feasibility in application which can be important in practical aspect.

• Therapeutic Science for Rehabilitation
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• v.12 no.1
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• pp.37-49
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• 2023

Object : This study aimed to identify the factor structure of Korean-Child Behavior Checklist 1.5-5 Dysregulation Profile (K-CBCL 1.5-5 DP) in infants and toddlers with mental disorders and verify differences in K-CBCL 1.5-5 DP among the diagnosis groups. Methods : The participants were 265 mothers of infants and toddlers with mental disorders who completed K-CBCL 1.5-5 DP. The data was analyzed using AMOS 25.0 and SPSS 25.0. Results : First, the bifactor model was the most suitable for the factor structure of the K-CBCL 1.5-5 DP. Second, there were significant differences among the diagnosis groups, such as communication disorders, pervasive developmental disorders, emotional disorders, and developmental delays. It was confirmed that the pervasive developmental disorder and emotional disorder groups showed significantly higher dysregulation compared with the communication disorder group. Conclusion : This study confirmed that infants and toddlers had dysregulation problems. Using the bifactor model, the multidimensional nature of the K-CBCL 1.5-5 DP was assessed. It was also meaningful that dysregulation could contribute to onset and deepening of symptoms of pervasive developmental disorders and emotional disorders in infancy.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.3
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• pp.15-21
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• 1999

The flow characteristics around KRISO 300K VLCC double-body model have been experimentally investigated in a closed-type subsonic wind tunnel. The local mean velocity and turbulence statistics including turbulent intensity. Reynolds shear stress and turbulent kinetic energy were measured using a x-type hot-wire probe. The measurements were carried out at several transverse stations of the stern and near wake regions. The surface flow was visualized using on oil-film technique to see the flow pattern qualitatively. The flow in the stern and near wake region revealed complicated three-dimensional flow characteristics. The VLCC model shows a hook-shaped wake structure behind the propeller boss in the main longitudinal vortex region. The thin boundary layer at midship was increased gradually in thickness over the stern and evolved into a full three-dimensional turbulent wake.