• Computers and Concrete
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• 제12권2호
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• pp.187-209
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• 2013

This paper presents a study on the prediction of transfer length of 13 mm seven-wire prestressing steel strand in pretensioned prestressed concrete members with rectangular cross-section including several material properties and design and manufacture parameters. To this end, a carefully selected database consisting of 207 different cases coming from 18 different sources spanning a variety of practical transfer length prediction situations was compiled. 16 single input features and 5 combined input features are analyzed. A widely used feedforward neural regression model was considered as a representative of several machine learning methods that have already been used in the engineering field. Classical multiple linear regression was also considered in order to comparatively assess performance and robustness in this context. The results show that the implemented model has good prediction and generalization capacity when it is used on large input data sets of practical interest from the engineering point of view. In particular, a neural model is proposed -using only 4 hidden units and 10 input variables-which significantly reduces in 30% and 60% the errors in transfer length prediction when using standard linear regression or fixed formulas, respectively.

• 대한토목학회논문집
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• 제31권5D호
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• pp.649-656
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• 2011

교통수요의 증가와 이용행태는 도로 건설로만 감당하기에는 한계에 도달했고 기존 시스템의 최대 활용을 도모함으로써 그 해결방안을 찾고자 하는 노력이 다방면에서 검토 연구되고 있는데 그 중 가장 대표적인 전략이 연결로 진입교통량을 통제하는 램프미터링 시스템(RMS)이다. 현재 운영되고 있는 서울외곽순환고속도로 장수~중동 구간 운영기준을 고찰하고, 지리적 및 교통상황을 고려한 운영기준을 재정립하였다. 이것을 위해 국내 및 해외 램프미터링 운영기준을 분석하였고, 단절점 분석으로 새로운 램프미터링 운영기준을 제시하였다.

• 한국수자원학회논문집
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• 제30권1호
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• pp.63-73
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• 1997

본 연구는 지하심부에 유류를 저장할 때 널리 이용되는 수막시설의 설치에 따른 공동주변의 흐름해석을 모의하기 위한 유한요소모형의 확립에 관한 것이다. 최종 행렬방정식의 대칭형 전체전도행렬을 풀기위해 벡터저장방식의 Choleski법을 이용하였으며, 전기상사법의 결과와 비교하여 모형을 검증하였다. 모형을 실제 비축기지에 적용하였으며, 대표적인 횡단면에 대해 요소망을 구성하여 공동내부의 압력과 수평수막설치에 따른 포텐션과 유속의 변화 등을 비교하고, 종단면에 대한 분석을 통해 연직수막설치에 따른 포텐셜의 변화와 인접공동간의 영향을 비교 분석한 결과 본 연구에서 확립된 모형은 공동주변 흐름해석에 유용하게 이용될 수 있는 것으로 확인되었다.

• 한국주조공학회지
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• 제4권4호
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• pp.5-13
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• 1984

This paper is presented for showing the effect of cooling rate on dendrite arm spacing, correlated with the chilling power of molding materials (conventional plaster, foamed plaster, silica sand) and section thickness, and also showing relationship between dendrite arm spacing and mechanical properties for an aluminum - 8.6 percent silicon - 3.6 percent copper alloy. Local solidification time $(t_f)$ and secondary dendrite arm spacing (d) could be varied widely in accordance with the molding materials and casting thickness, and the following relationship is obtained: $d=9.4t_f\;^{0.31}$ A good correlation between dendrite arm spacing and mechanical properties such as ultimate tensile strength, yield strength, hardness was found, that is, mechanical properties decreased in a linear manner with increase in log of secondary dendrite arm spacing. Ultimate tensile strength in conventional plaster mold casting decreased by 15 percent comparing with the sand casting, where as in foamed plaster mold casting, it decreased by 30 percent comparing with the sand casting. From those results, it has been verified that DAS might be the most representative parameter for predicting mechanical properties varing with the different cooling condition.

• 건축역사연구
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• 제25권6호
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• pp.73-80
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• 2016

A discourse on the Independence Hall of Korea, a representative cultural project of the 1980s, has been understood as a repetition of the traditional debate of the 1960s. It was considered as a petrified propaganda aimed at ensuring the fragile legitimacy of the military regime, and the architect as a sympathizer. Even if all these facts are true, it does not give any explanation for the architecture. Scrutinizing the building process and the change of discourse in the Independence Hall of Korea, this paper tries to explore a section of contemporary Korean architecture in the 1980s. The architect who designed the Independence Hall of Korea is Kim Kiwoong, however, it was Kim Won who took charge of overall scheme for it. Kim Won replaced the role of a technocrat in the 1960s, who deprived architects of his autonomy. Against this backdrop, Kim Kiwoong attempted to explain his own building via various concept like postmodernism, which gave him very proper context. But, later, he appropriated words like void and madang. These derived from some architectural historian's researches in 1970s, and were to predict the architecture of the 1990s.

• 한국보건간호학회지
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• 제25권2호
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• pp.197-208
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• 2011

Background: This study investigated the hearing status in Korean adults according to data from the Korea National Health and Nutrition Examination Survey 2009. Methods: The data of 3,479 adults(${\geq}20$ years, 1,492 men, 1,987 women) collected by the Korean Center for Disease Control was analyzed using ${\chi}^2$-test and logistic regression. Results: Differences in hearing loss according to individual factors were evident by follows gender, region, education status, economic status, current smoking and recognition of stress. Differences in - hearing loss according to ear related factors were evident subjective hearing status, experience of tinnitus, prevalence of chronic otitis media, and tympanomembrane abnormality. Conclusion: Hearing-related disorders can cause many social problems. This study investigated a representative cross-section of Koreans to determine the hearing status. The study was limited in that the risk factors of hearing loss were not identified. It is also recommended that a program be developed that can help control the variables identified in this study along with follow-up studies to verify the model.

• 한국정보통신학회논문지
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• 제18권12호
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• pp.2864-2870
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• 2014

시스템 및 네트워크의 끊김 없는 안정적인 서비스를 위해 다양한 서비스 지원방안이 제안되었다. 대표적으로 복수의 서비스 시스템으로 안정적인 서비스를 지원하는 이중화가 있다. 다양한 이중화 시스템이 제안되었고 이러한 이중화 시스템은 서비스 지원 시스템의 개수에 따라 다양한 형태를 가진다. 본 논문에서는 복수의 이중화 시스템에 대하여 다양한 이중화 모델의 가용도를 분석하고자 한다. 가용도분석도구로는 복잡한 이중화 시스템을 비교적 간단히 분석 가능한 SRN기반의 SPNP를 이용한다. 본 논문은 다양한 이중화 모델을 설명하고 서비스 지원 시스템의 개수에 따른 이중화 모델의 가용도를 SPNP를 이용하여 비교 분석한다.

• Steel and Composite Structures
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• 제34권1호
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• pp.53-73
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• 2020

A novel all-steel miniature bar-type structural fuse (MBSF) with cold formed bolted connections is developed in this study, which consists of a central energy dissipation core cut from a smooth round bar, an external confining tube and nuts. Three types of cross sections for the central energy dissipation core, i.e., triple-cut, double-cut and single-cut cross sections, were studied. Totally 18 specimens were axially tested under either symmetric or asymmetric cyclic loading histories, where the parameters such as cut cross sectional area ratio, length of the yielding portion and cross sectional type were investigated. Numerical simulation of 2 representative specimens were also conducted. An analytical model to evaluate the bending failure at the elastic portion was proposed, and a design method to avoid this failure mode was also presented. The experimental results show that the proposed MBSFs exhibit satisfactory hysteretic performance under both the two cyclic loading histories. Average strain values of 8% and 4% are found to be respectively suitable for designing the new MBSFs as the ultimate strain under the symmetric and asymmetric cyclic loadings.

• 한국생산제조학회지
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• 제20권3호
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• pp.219-224
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• 2011

Aluminum or CFRP is representative one of the lightweight materials. Collapse behavior of Al/CFRP square structural member was evaluated in this study based on the respective collapse behavior of aluminum and CFRP member. Al/CFRP square structural members were manufactured by wrapping CFRP prepreg sheets outside the aluminum hollow members in the autoclave. Because the CFRP is an anisotropic material with mechanical properties, The Al/CFRP square structural members stacked at different angles(${\pm}15^{\circ}$, ${\pm}45^{\circ}$, ${\pm}90^{\circ}$, $90^{\circ}/0^{\circ}$ and $0^{\circ}/90^{\circ}$ where the direction on $0^{\circ}$ coincides with the axis of the member) and interface numbers(2, 3, 4, 6 and 7). The axial impact collapse tests were carried out for each section members. Collapse mode and energy absorption characteristics of the each member were analyzed.

• 디지털콘텐츠학회 논문지
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• 제8권4호
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• pp.475-481
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• 2007

본 연구는 공공공간의 하나인 천안역을 중심으로 사인에 있어서 분포 및 종류를 분류하고 구간별로 조사 분석한 연구이며, 그 결과로 구간별 설치된 사인의 종류에 대한 문제, 사인의 설치에 있어서 위치에 대한 문제, 밀집되어 설치된 정보(사인)에 대한 문제가 나타났다. 이에 각 구간별 설치된 정보(사인)의 차이와 밀집되게 설치되어 있는 정보에서 각 장소에 고르게 분배되는 정보제공의 필요성과, 사인의 무계획적인 설치에서 이용자의 행동을 고려한 적절한 위치의 정보 설치가 요구된다. 따라서 사인의 설치에는 장소마다 보행자에게 필요한 정보의 파악이 우선되어야 하며 그 장소마다 적절한 정보의 제공으로 이용자에게 안정적인 환경 부여가 필요하다.