• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.541-544
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• 1999

The main objective of this study is to develope the PSC-I girder for long span bridge. This study investigates the structural behavior of Postcracking stage and efficiency of proposed PSC-I girder using 1/2 scaled prototype beam specimen. Three specimens are tested under three point static loading system. Ideally, the Load-displacement relationship is trilinear. The crack patterns and failure mode of each specimen are reported in this paper and they are compared to each other with ductility and strength.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.364-369
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• 2003

Crack propagation and AE characteristics of CFRP plain woven laminate composites are examined with acoustic sensor by AEDSP 32/16 board in PC system. AE signals are measured during the fracture behavior tests. The purpose of study is the estimation of the crack extension behavior effected between three kinds of fiber orientation for plain woven CFRP laminate composite and the relationship between AE characteristics and load-displacement curves and crack extension length.

• 한국의류학회지
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• 제23권6호
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• pp.853-863
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• 1999

the change of physical properties (thickness, weight, air permeability) and mechanical properties(abrasion resistance breaking load and displacement) of samples were determined after heat exposure by a RPP tester. The effect of exposure time and heat flux intensity on the changes and the relationship between physical properties and mechanical properties were investigated. FR treated cotton Kevlar/PBI and Nomex with different structureal characteristics were chosen for specimens. The changes of physical properties and mechanical properties were calculated based on their initial values before heat exposure. The longer exposure time and the high heat flux intensity the more changes of those properties. Heat flux intensity was more effective on the changes, The showed to be affected by an interplay of shrinkage and pyrolysis products loss. The changes of thickness and abrasion resistance showed to be higher for plain weave fabric and those of air permeabiliyt and breaking load and displacement for twill weave fabric. While FR treated cotton which have high RPP value experienced serious and detrimental changes after heat exposure Kevlar/PBI which has low RPP value showed no high changes. In conclusion it could be confirmed that when total performance of a protective clothing is estimated retention capability of physical and mechanical properties after heat exposure as well as RPP value must be considered.

• Computational Structural Engineering : An International Journal
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• 제1권2호
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• pp.117-130
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• 2001

Investigations of low-rice unbounded reinforced concrete shear walls with or without openings are performed with comparison of analytical and experimental results. Theoretical analysis is based on nonlinear finite element algorithm, which incorporates concrete failure criterion and nonlinear constitutive relationships. Studios focus on the effects of height-to-length ratio of shear walls, opening ratio, horizontal and vertical reinforcement radios, and diagonal reinforcement. Analytical solutions conform well with experimental results. Equations for cracking, yielding and ultimate loads with corresponding lateral displacements are derived by regression using analytical results and experimental data. Also, failure modes of low-rise unbounded shear walls are theoretically investigated. An explanation of change in failure mode is ascertained by comparing analytical results and ACI code equations. Shear-flexural failure can be obtained with additional flexural reinforcement to increase a wall's capacity. This concept leads to a design method of reducing flexural reinforcement in low-rise bounded solid shear wall's. Avoidance of shear failure as well as less reinforcement congestion leer these walls is expected.

• Tribology and Lubricants
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• 제30권2호
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• pp.99-107
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• 2014

Fretting corrosion tests are conducted with a constant displacement amplitude using silver-plated brass coupons to investigate the effect of contact pressure on fretting corrosion. Three behaviors are identified based on the change in electric resistance and friction coefficient during the fretting test period, and the identified behaviors are dependent on the magnitude of the applied load. The failure cycle ($N_f$) with an electric resistance of 0.1 D cannot be achieved due to the adhesion behavior of the metal and metal contact under the higher applied load of 0.45 N. This suggests that an average contact pressure higher than 159 MPa for the silver-coated connector is desirable to gain an almost infinite lifetime. The relationship between the electric contact resistance (R) and the average contact pressure (p) can be written as $p=106.2{\times}{\Omega}^{-1.5}$.

• Earthquakes and Structures
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• 제24권6호
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• pp.415-428
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• 2023

Low-cost techniques with seismic isolation performance and excellent resilience need to be explored in the case of rural low-rise buildings because of the limited buying power of rural residents. As an inexpensive and eco-friendly isolation bearing, scrap tire pads (STPs) have the issue of poor resilience. Thus, a seismic isolation system under a column (SISC) integrated with STP needs to be designed for the seismic protection of low-rise rural buildings. The SISC, which is based on a simple exterior design, maintains excellent seismic performance, while the mechanical behavior of the internal STP provides elastic resilience. The horizontal behaviors of the SISC are studied through load tests, and its mechanical properties and the intrinsic mechanism of the reset ability are discussed. Results indicate that the average residual displacement ratio was 24.59%, and the reset capability was enhanced. Comparative experimental and finite element analysis results also show that the load-displacement relationship of the SISC was essentially consistent. The dynamic characteristics of isolated and fixed-base buildings were compared by numerical assessment of the response control effects, and the SISC was found to have great seismic isolation performance. SISC can be used as a low-cost base isolation device for rural buildings in developing countries.

• 한국지반신소재학회논문집
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• 제20권4호
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• pp.125-131
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• 2021

본 연구에서는 DCM으로 보강된 연약지반의 거동특성을 평가하기 위하여, 모형실험결과를 이용하여 DCM 배치 형상에 따른 침하-측방변위, 침하-융기 관계를 분석하였다. 그 결과, 모형지반의 지표면 누적 침하 거동은 DCM이 적용된 지반에서 상대적으로 침하가 적게 발생하였고, 격자식, 벽식, 말뚝식의 순으로 동일한 하중조건에서 침하량이 적게 발생한 것을 알 수 있었다. 이와 같은 경향은 측방변위량과 융기량에 대해서도 동일하게 나타난 것을 확인하였다. 연약지반의 침하와 측방유동의 관계를 분석한 결과, 기존 연구(Leroueil et al., 1990)와 유사한 거동을 보이는 것으로 확인되었다. DCM 배치 형상에 따른 지반개량효과를 평가한 결과, 측방유동과 지반 융기에 대하여 격자식 보강이 벽식 및 말뚝식 보강에 비해 탁월한 지반개량효과를 보유한 것으로 평가되었다.

• 대한기계학회논문집
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• 제12권2호
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• pp.185-192
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• 1988

본 논문에서는 접촉문제를 보다 정교하게 수식화 함으로써 효율적인 볼 압입 시험 시뮬레이션 방법을 제시하고 이를 실제에 적용하여 방법의 유용성을 보이고자 한다. 아울러 실험을 병행하여 결과를 비교함으로써 해석결과의 신뢰성을 검토한다.

• Advanced Composite Materials
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• 제18권1호
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• pp.21-42
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• 2009

The vibration characteristics of post-buckled laminated composite doubly curved shells are investigated. The finite element method is used for the analysis of post-buckling and free vibration of post-buckled laminated shells. The geometric non-linear finite element model includes the general non-linear terms in the strain-displacement relationships. The shell geometry used in the present formulation is derived using an orthogonal curvilinear coordinate system. Based on the principle of virtual work the non-linear finite element equations are derived. Arc-length method is implemented to capture the load-displacement equilibrium curve. The vibration characteristics of post-buckled shell are performed using tangent stiffness obtained from the converged deflection. The code is first validated and then employed to generate numerical results. Parametric studies are performed to analyze the snapping and vibration characteristics. The relationship between loads and fundamental frequencies and between loads and the corresponding displacements are determined for various parameters such as thickness ratio and shallowness.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 1998년도 춘계 학술논문발표회 논문집
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• pp.89-97
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• 1998

In this study, under large scale yielding conditions crack propagation is found to governed by parameters based on the J-integral or on the crack opening displacement. But initiation of crack propagation of ductile material seems to be controlled by just on parameter that is the strain. The relationship between the critical value of J-integral and the local fracture strain in uniaxial tensile test in the region of maximum reduction in area. Therefore, the fundamental theorectical equation by the proposed elastic-plastic fracture toughness and the local fracture strain has a merit. in comparison with the ASTM method, which can measure by using the load-displacement curve and the specimens in tenslie test.