• 한국지진공학회논문집
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• 제9권6호
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• pp.1-12
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• 2005

비보존력(non-conservative force)을 받는 외팔기둥의 동적 안정성 거동특성을 조사하기 위하여, 전단변형 및 감쇠효과가 고려된 Hamilton의 원리를 적용하고 무차원화 된 운동방정식 및 유한요소 정식화 과정을 제시한다. 유도된 행렬운동방정식을 이용하여 외팔보(Beck's column)의 고유치해석에 의한 정적좌굴(divergence) 및 동적 좌굴하중(flutter load)을 산정하고 $Newmark-{\beta}$법에 의해서 시간응답해석을 실시한다. 이러한 해석법을 이용한 매개변수연구를 통하여 전단변형 및 회전관성효과, 비보존력의 방향파라미터에 대한 임계하중의 영향, 그리고 내적 및 외적 감쇠하중의 영향이 비보존력계의 동적 안정성에 미치는 영향을 분석한다.

• 한국광학회지
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• 제15권4호
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• pp.309-312
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• 2004

레이저 홀로그래피 방법과 반응성 이온식각 방법(RIE: reactive ion etching)을 사용하여 2차원 광자결정을 제작하였다. 육변형(hexagonal) 및 사변형(square) 광자결정 격자는 첫 번째 레이저 노광 후 시편을 각각 60도 및 90도 회전하고 다시 두 번째 노광을 통하여 제작할 수 있었다. 또한 사변형 광자결정 격자의 나노컬럼(nanocolumn)의 크기와 주기는 레이저 입사각에 따라 각각 125∼145 nm, 220∼290 nm로 미세한 조정이 가능하였다. 마지막으로 CH$_4$/H$_2$ 가스를 이용한 반응성 이온식각 방법을 통하여 aspect ratio가 1.5 이상인 InP/InGaAsP nanocolumn을 제작 할 수 있었다.

• 한국강구조학회 논문집
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• 제11권3호통권40호
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• pp.311-318
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• 1999

콘크리트충전 강관은 콘크리트와 강관의 합성작용으로 인한 내력의 증가와 우수한 변형능력 등의 많은 장점이 있으나 현장에서 강관에 콘크리트를 타설할 때 충전된 콘크리트의 충전성에 대한 신뢰도가 떨어질 수 있다. 본 연구에서는 콘크리트의 공장타설에 의한 콘크리트충전 각형강관기둥의 프리훼브화로 콘크리트의 충전성을 확보하기 위한 목적으로 현장에서의 기둥 이음방식을 용접과 고강도 무수축 모르터를 사용한 접합방법을 사용하여 이에 대한 실험을 하였다. 본 연구는 이러한 시공법을 선택할 경우 콘크리트를 미리 타설한 기둥과 기둥을 접합할 때 그 이음부의 역학적 특성을 파악하여 실제 현장에서 실시하고 있는 방법인 현장 타설방법과 동등한 능력을 발휘할 수 있는 지를 확인하고 그 방법에 대한 영향인자를 파악하고 분석하는 기초적 연구이다.

• 한국강구조학회 논문집
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• 제18권6호
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• pp.687-696
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• 2006

본 논문에서는 공간 뼈대구조의 탄-소성 후좌굴 강도를 파악하기 위한 효율적인 수치해석 기법을 개발하고, 매개변수해석을 통하여 보-기둥 및 뼈대구조물의 비탄성 후좌굴 거동을 분석하였다. 외력의 증가에 따라 점진적인 강도감소효과를 효율적으로 고려하는 개선된 소성힌지 해석법을 적용하여 문헌에서 제시된 다양한 잔류응력 분포 형태에 따른 뼈대구조물의 탄-소성 해석을 수행하였다. 요소의 소성화 진행정도를 나타내는 파라미터들을 도입하고 등가단면력 및 요소분할에 따른 매개변수해석을 수행하여 그 결과를 문헌에서 제시된 소성영역해석, 쉘요소를 이용한 정밀해석 그리고 실험결과와 비교하여 뼈대구조물 극한강도를 평가하였다.

• 한국농공학회지
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• 제42권4호
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• pp.106-114
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• 2000

An investigation was conducted to get the basic data for establishing maintenance strategy of pipe framed greenhouses. The contents of the investigation consisted of actual state of structures, maintenance status, meteorological disaster, and corrosion characteristics of pipe framework in greenhouses. the number of greenhouses investigated was 108 in total. Most multi-span greenhouses had narrower width and lower height than the standared 1-2W greenhouse, and most of single-span greenhouses were tunnel type. In multi-span greenhouses, the size and interval of frameworks such as rafter, purline, column , and cross beam were mostly suitable, but frameworks of single-span greenhouses were mostly insufficient. After about 7 years in grounds, 8 years in joints, 10 years in bending parts. and 13 years in columns. pipe surface was mostly rusted. Most weak parts in corrosion were pipes in contact with the ground, joints, roll-up shaft pipes, and pipes close to the gutter. Almost all of the greenhouse farmers didn't pay any attention to maintenance affair in a regular interval for pipe framed grenhouses. Many greenhouses have experienced the meteorologicla diaster such as uplift of foundation, partial or complete failure by the hyphoon and/or high winds.

• 건축역사연구
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• 제25권6호
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• pp.7-16
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• 2016

The purpose of this study is to find framework schema of early J usimpo-style Buddhist halls (Geungnakjeon Hall of Bongjeongsa Temple, Muryangsujeon Hall of Buseoksa Temple, and Daeungjeon Hall of Sudeoksa Temple). Though the halls are known as built in the late Goryeo Period, they show the influence of the architectural style of the early Unified Silla Period. To find the adopted modules and proportions of these halls, this study conceived a schematic diagram based on the whole frame structure taking reference from the Cai-Fen system in Yingzao Fashi. In these three halls, the heights of each cross-beam (Dori) are made up by the layers of member and member units. This study computes the values of Cai, Zhi, and Fen which can apply to both the section and the plan. The vertical section structure is determined by combining the standard member heights (Cai) and the standard unit heights (CaiZhi). The bays of columns are made by multiples of the standard member width (Fen).

• Structural Engineering and Mechanics
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• 제15권4호
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• pp.415-436
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• 2003

The combination of spatial latticed structures (hereafter SLS) and flexible cables, the cable-stayed spatial latticed structures (hereafter CSLS) can cross longer span. According to variation principle, a novel geometric nonlinear formulation for 3-D bar elements considering large displacement and infinitesimal rotation increments with second-order precision is developed. The cable nonlinearity is investigated and it is taken that the secant modulus method can be considered as an exact method for a cable member. The tower column with which the cables link is regarded as a special kind of beam element, and, a new simplified stiffness formulation is presented. The computational strategies for the nonlinear dynamic response of structures are given, and the ultimate load carrying capacities and seismic responses are analyzed numerically. It is noted that, compared with corresponding spatial latticed shells, the cable-stayed spatial latticed shells have more strength and more stiffness, and that the verical seismic responses of both CSLS and CLS are remarkably greater than the horizontal ones. In addition, the computation shows that the stiffness of tower column influences the performance of CSLS to a certain extent and the improvement of structural strength and stiffness of CSLS is relevant not only to cables but also to tower columns.

• Earthquakes and Structures
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• 제6권5호
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• pp.561-580
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• 2014

After strong earthquakes conventional frames used worldwide in multi - story steel buildings (e.g. moment resisting frames) are not well positioned according to reparability. Two innovative systems for seismic resistant steel frames incorporated with dissipative fuses were developed within the European Research Program "FUSEIS" (Vayas et al. 2013). The first, FUSEIS1, resembles a vertical Vierendeel beam and is composed of two closely spaced strong columns rigidly connected to multiple beams. In the second system, FUSEIS2, a discontinuity is introduced in the composite beams of a moment resisting frame and the dissipative devices are steel plates connecting the two parts. The FUSEIS system is able to dissipate energy by means of inelastic deformations in the fuses and combines ductility and architectural transparency with stiffness. In case of strong earthquakes damage concentrates only in the fuses which behave as self-centering systems able to return the structure to its initial undeformed shape. Repair work after such an event is limited only to replacing the fuses. Experimental and numerical investigations were performed to study the response of the fuses system. Code relevant design rules for the seismic design of frames with dissipative FUSEIS and practical recommendations on the selection of the appropriate fuses as a function of the most important parameters and member verifications have been formulated and are included in a Design Guide. This article presents the design and performance of building frames with FUSEIS 1-1 based on models calibrated on the experimental results.

• Steel and Composite Structures
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• 제29권4호
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• pp.423-435
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• 2018

There are presently two general ways of accounting for hazardous metal creep in structural fire analyses: either we incorporate creep strains implicitly in hardening model ('implicit-creep' plasticity) or we account for creep explicitly ('explicit-creep' plasticity). The first approach is simpler and usually used for fast engineering applications, e.g., following proposals of EN 1993-1-2. Prioritizing this approach without consideration of its limitations, however, may lead to significant error. So far the possible levels of such error have been demonstrated by few researchers for individual structural elements (i.e., beams and columns). This paper, however, presents analyses also for selected beam-girder assemblies. Special numerical models are developed correspondingly and they are validated and verified. Their important novelty is that they do not only account for creep in individual members but also for creep in between-member connections. The paper finally shows that outside the declared applicability limits of the implicit-creep plasticity models, the failure times predicted by the applied alternative explicit-creep models can be as much as 40% shorter. Within the limits, however, the discrepancies might be negligible for majority of cases with the exception of about 20% discrepancies found in one analysed example.

• Steel and Composite Structures
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• 제19권2호
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• pp.293-308
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• 2015

Interaction between the external thin-walled steel tube and the internal concrete core significantly increases the bending resistance of composite beams and beam-columns in comparison with the steel or concrete members. There is presented a developed method for design of hollow and solid concrete-filled steel tubular beams based on test data, which gives better agreement with test results than EC4 because its limitation to take an increase in strength of concrete caused by confinement contradicts the recommendation of 6.7.2(4) that full composite action up to failure may be assumed between steel and concrete components of the member. Good agreement between the results of carried out experimental, numerical and theoretical investigations allows recommending the proposed method to use in design practice.