• 대한조선학회논문집
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• 제47권5호
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• pp.697-702
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• 2010

A WIG(Wing-In-Ground effect) craft flies close to the water surface by utilizing a cushion of relatively high pressurized air between its wing and water surface. This implies that when one designs such craft it is important to have lightweight structures with adequate strength to resist external loads with some margins. To investigate this requirement, this paper deals with the structural analysis of the bottom plate of small WIG craft having a design landing weight of 1.2-ton. As building materials for the WIG craft, pre-preg carbon/epoxy composites are considered. The strength information of the bottom plate is obtained using the first-ply-failure analysis in conjunction with a mid-plane symmetric laminated plate theory. As a result, the first-ply-failure location, load and deflection of the bottom plate are obtained. The calculated strength information is compared with the water reaction load for the bottom plate of seaplanes considered when they land on the water surface -the same fluid-structure interaction mechanism as that of WIG craft. In the calculation of seaplane water reaction load information, the rules shown in FAR(Federal Aviation Regulations) Part 25 are used. Through the comparison, the structural integrity of the bottom plate for the WIG craft is checked.

• 반도체디스플레이기술학회지
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• 제8권2호
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• pp.55-58
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• 2009

Density functional theory was used to investigate the adsorption and reaction of $HfCl_4$ with two hydroxyls on Si (001)-$2{\times}1$ surface in atomic layer deposition (ALD) process. We prepared a reasonable Si substrate which consisted of six inter-dimer dissociated $H_2O$ molecules and two intra-dimer dissociated $H_2O$ molecules. The $HfCl_4$must react with two hydroxyls to be a bulk-like structure. When $HfCl_4$ was adsorbed on a hydroxyl, there was energy benefit of -0.55 eV. Though there was energy loss for $HfCl_4$ to react with H of hydroxyl, thermal energy of ALD chamber would be enough to pass the energy barriers. There were five reaction pathways for $HfCl_4$ to react with two hydroxyls; inter-dimer, intra-dimer, cross-dimer, inter-row, and cross-row. Inter-row, inter-dimer and intra-dimer were relatively favorable among the five reaction pathways based on the energy difference. The electron densities between O and Hf in these three reactions were higher than the others and they had shorter Hf-O and O-O bond lengths than the other two reaction pathways.

• Nuclear Engineering and Technology
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• 제42권4호
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• pp.450-459
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• 2010

The present paper investigates the collapse pressure of cylinders with intermediate thickness subjected to external pressure based on detailed elastic-plastic finite element (FE) analyses. The effect of the initial ovality of the tube on the collapse pressure was explicitly considered in the FE analyses. Based on the present FE results, the analytical yield locus, considering the interaction between the plastic collapse and local instability due to initial ovality, was also proposed. The collapse pressure values based on the proposed yield locus agree well with the present FE results; thus, the validity of the proposed yield locus for the thickness range of interest was verified. Moreover, the partial safety factor concept based on the structural reliability theory was also applied to the proposed collapse pressure estimation model, and, thus, the priority of importance of respective parameter constituting for the collapse of cylinders under external pressure was estimated in this study. From the application of the partial safety factor concept, the yield strength was concluded to be the most sensitive, and the initial ovality of tube was not so effective in the proposed collapse pressure estimation model. The present deterministic and probabilistic results are expected to be utilized in the design and maintenance of cylinders subjected to external pressure with initial ovality, such as the once-through type steam generator.

• 한국건설관리학회논문집
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• 제22권5호
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• pp.3-16
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• 2021

이 연구의 목적은 구성주의 교육이론 기반의 BIM/IPD(통합프로젝트수행)교육에 적합한 BIM협업 교육모델제안과 그 교육모델의 효율성을 검증하는 것이다. BIM/IPD기반 협업능력은 건설 전 분야 걸쳐 필요한 역량으로 보고 있다. '구성주의 협업 프로세스' 교육 방식을 실험군(구성주의 협업프로세스)과 대조군(빌딩스마트 협회 BIM 코디네이터 과정)에 적용하여 학습 전후의 상호작용 과정에서 학습효과의 개선을 인지측정(협업의 만족도, 협업의 수준)하고 실무능력(협업고도화지수측정)측정을 통한 '구성주의 협업프로세스'의 학습효과를 검증하는 것이다.

• Smart Structures and Systems
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• 제24권1호
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• pp.53-65
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• 2019

Misaligned wind-wave and seismic loading render offshore wind turbines suffering from excessive bi-directional vibration. However, most of existing research in this field focused on unidirectional vibration mitigation, which is insufficient for research and real application. Based on the authors' previous work (Sun and Jahangiri 2018), the present study uses a three dimensional pendulum tuned mass damper (3d-PTMD) to mitigate the nacelle structural response in the fore-aft and side-side directions under wind, wave and near-fault ground motions. An analytical model of the offshore wind turbine coupled with the 3d-PTMD is established wherein the interaction between the blades and the tower is modelled. Aerodynamic loading is computed using the Blade Element Momentum (BEM) method where the Prandtl's tip loss factor and the Glauert correction are considered. Wave loading is computed using Morison equation in collaboration with the strip theory. Performance of the 3d-PTMD is examined on a National Renewable Energy Lab (NREL) monopile 5 MW baseline wind turbine under misaligned wind-wave and near-fault ground motions. The robustness of the mitigation performance of the 3d-PTMD under system variations is studied. Dual linear TMDs are used for comparison. Research results show that the 3d-PTMD responds more rapidly and provides better mitigation of the bi-directional response caused by misaligned wind, wave and near-fault ground motions. Under system variations, the 3d-PTMD is found to be more robust than the dual linear TMDs to overcome the detuning effect. Moreover, the 3d-PTMD with a mass ratio of 2% can mitigate the short-term fatigue damage of the offshore wind turbine tower by up to 90%.

• 디지털융복합연구
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• 제17권2호
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• pp.339-345
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• 2019

본 연구는 젊은 세대들이 한복에 관심을 가지고 직접 경험을 하는 한복체험이라는 새로운 문화의 사용자 경험에 대한 연구로 존 듀이(John Dewey)의 경험이론과 도널드 노먼(Donald Norman)이 정의한 사용자경험을 통해 경험의 정의를 살피고 사용자의 경험을 분석하는데 목적을 둔다. 우선적으로 인구 통계학적 특성을 알아보기 위해 일반인을 대상으로 온라인 설문조사를 진행하였고 설문 결과에 따라 주요 체험자인 20대 여성 6명을 임의로 선정하여 다양한 사용자 의견을 얻기 위해 대면 인터뷰를 진행하였다. 인터뷰 결과의 공통된 의견을 분류하였을 때 체험자들은 한복의 전통성을 인지하기 보다는 현대화된 한복의 심미성을 먼저 인지하였고 한복체험이라는 경험을 함께 공유하고자 하는 욕구로 사회성, 비일상적인 문화가 되어 버린 한복을 특별하다 인지하는 특이성과 같은 특징이 분석되었다. 또한 사용자들은 자신이 직접 겪은 경험을 특별하다 인지하기 때문에 시장성 있는 문화콘텐츠 개발을 위해서는 지속적으로 사용자들의 욕구를 분석하고 연구해야 할 것이다.

• Journal of Information Science Theory and Practice
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• 제6권4호
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• pp.6-16
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• 2018

This article shows an approach to the study of two fundamental aspects of the prepublication of scientific manuscripts in specialized repositories (arXiv). The first refers to the size of the interaction of "standard papers" in journals appearing in the Web of Science (WoS)-now Clarivate Analytics-and "non-standard papers" (manuscripts appearing in arXiv). Specifically, we analyze the citations found in the WoS to articles in arXiv. The second aspect is how publication in arXiv affects the citation count of authors. The question is whether or not prepublishing in arXiv benefits authors from the point of view of increasing their citations, or rather produces a dispersion, which would diminish the relevance of their publications in evaluation processes. Data have been collected from arXiv, the websites of the journals, Google Scholar, and WoS following a specific ad hoc procedure. The number of citations in journal articles published in WoS to preprints in arXiv is not large. We show that citation counts from regular papers and preprints using different sources (arXiv, the journal's website, WoS) give completely different results. This suggests a rather scattered picture of citations that could distort the citation count of a given article against the author's interest. However, the number of WoS references to arXiv preprints is small, minimizing this potential negative effect.

• 한국콘텐츠학회논문지
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• 제18권12호
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• pp.489-502
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• 2018

중국 도시재생 과정 속에서 정부, 기업, 시민, 전문가들 간의 대화와 상호작용을 강화하는 것이 필요하다는 것에서 시작되었다. 중국 도시재생이론의 대부분은 거시적 차원의 정책에만 머물러 있어, 참여주체의 소통을 세부적으로 분석하여 도시재생문제를 해결하고자 하는 연구의 수는 매우 부족한 현실이다. 그래서 본 연구는 사례분석과 설문조사를 통해 중국 도시재생의 의사소통에 관한 평가하고자 한다. 도시재생 사례에서 나타난 소통 요소를 분석하며, 그에 따른 연구 분석사례의 범위로는 2000년 이후 최근 중국 도시재생 사례분석과 전문가 설문조사를 병행 하였다. 본 논문의 연구결과인 도시재생 평가모델은 중국 현 단계의 국가운영에 적합하며, 현재 중국이 응용가능한 도시재생모형이라고 판단된다.

• 한국구조물진단유지관리공학회 논문집
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• 제23권2호
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• pp.99-106
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• 2019

횡력을 받는 전단벽-골조 시스템은 휨거동을 하는 전단벽과 전단거동을 하는 골조가 슬래브의 강체평면운동(Diaphragm Action)을 통하여 상호작용하여 수평력에 효율적으로 저항하는 시스템이다. 횡력을 받는 골조의 거동은 보와 기둥의 휨 변형에 의한 골조의 수평 전단변형과 기둥의 축 변형에 의한 골조의 휨 변형으로 구분 할 수 있다. 일반적으로 전단벽-골조 시스템의 근사해석 시 골조의 휨변형은 무시하여 왔으나, 건물의 높이가 증가 할수록 골조의 휨 거동은 큰 영향을 미칠 것으로 사료된다. 따라서 본 연구에서는 횡력을 받는 전단벽-골조 시스템의 근사해석 시 기둥의 축 변형을 고려하기위하여 병렬전단벽 시스템(Coupled Shear Wall System)의 해석 시 사용하는 연속매체모델(Continuous Medium Model)을 이용하여 횡 변위 및 부재력을 산정할 수 있는 근사식을 수정 제시 하였다. 새롭게 제시된 근사식을 검토하기 위하여 기존 식과 컴퓨터에 의한 Matrix해석 결과와 비교하였으며, 비교결과 건물 높이가 높을수록 본 연구에서 제시한 근사해석 식이 기존 식보다 Matrix 해석 결과에 가깝게 나타났다.

• 한국해양공학회지
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• 제33권2호
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• pp.123-130
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• 2019

The flow around a curved riser exposed to the current in various directions was investigated at a Reynolds number of 100 using a numerical simulation. The present study found that the flow features of the curved riser were distinct from those of a straight riser as a result of its large radius of curvature. Namely, there were various wake patterns according to the flow's incident angle. As the incident angle increased from $0^{\circ}$ to $90^{\circ}$, a two-row street of vortices that developed along the centerline of the curved riser became more apparent. However, when the incident angle approached $180^{\circ}$ from $90^{\circ}$, these vortices were completely suppressed by the interaction between the wake and an axial flow induced by the curvature of the riser. To identify this feature, the sectional force coefficients were also considered, and it was found that the force coefficients could be different from those found in a sectional analysis based on the strip theory when investigating vortex-induced vibration. As a result, this kind of study would be important to realistically estimate the riser VIV (vortex-induced vibration) and fatigue life, and a new force coefficient database that includes the three-dimensional effect should be established.