• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.723-730
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• 2006

In the electrical railway, the tension ascension of contact wire is essential to speed up of train and current collection performance of catenary largely depends on the tension. The tension variation rate of the tensioning device used in existing line limits within 5%, and the tension variation rate of the spring-type tensioning device installed at the section where tensioning length is short bounds within 15%. So it is urgent for us to localize it for high speed line, which the tension variation rate is limited within 3%. Therefore in this study, a pulley-type tensioning device for high speed line is developed. To verify the performance of developed device, a performance test, overload test and failure test is carried out under the code of the Kyung-Bu High Speed line. And it is secured durability performance through a fatigue test.

• KCI Concrete Journal
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• 제12권1호
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• pp.69-77
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• 2000

The reinforced concrete(RC) flexural members strengthened with steel plate/CFS at soffit have initial stresses and strains in reinforcements and concrete caused by the service loads at the time of retrofitting works. These initial residual stresses and strains of strengthened beams may affect the flexural performance of the rehabilitated beams. The objective of this study is to evaluate and verify the effectiveness of rehabilitation by external bonded steel plates and CFS to the tension face of the beams under three conditions of pre-loading. Thirteen beam specimens are tested and analyzed. Main test parameters are pre-loading conditions, strengthening materials and reinforcement ratio of specimens. The effect of test parameters on the strengthened beams is analyzed from the maximum load capacity, load-deflection relationship, state of stress of the materials. crack propagation phase, and failure modes. Both test results and design formulas of ACI Code provisions are compared and evaluated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.105-108
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• 2006

Current ACI and AIJ guidelines only address the importance of the concrete strength and geometry of the joint. There are no significant attention paid to other variables. In addition, the current design code doesn't predict the ductility of the beam-column assemblies. The former researcher proposed the analytical model to predict the shear strength of the joint panel as well as the ductility of the beam-column assemblies in year 2004. In this study, the experiments to investigate shear behavior of reinforced concrete beam-column joints and to verify proposed model were carried out, based on the experimental results. As the formal researcher proposed, the factor K (K=0.5), the ductility of BJ-failure was predicted reasonably when the transverse reinforcement ratio exceeded 0.0186. However, the proposed equation showed a large discrepancies in the ductility estimating when transverse reinforcement ratio was below 0.0186.

• 정보처리학회논문지C
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• 제16C권3호
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• pp.317-324
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• 2009

본 논문은 IEEE 802.11i의 4-way 핸드쉐이크 프로토콜을 안전성과 신뢰성의 측면에서 분석한다. 분석을 통해 MIC 오류와 같은 특정한 상황에서 4-way 핸드쉐이크가 정상적으로 수행되지 못하는 것을 보여주고 문제 해결을 위한 수정방안을 제안한다. 또한 4-way 핸드쉐이크 프로토콜보다 안전하고 효율적인 2-way 핸드쉐이크 프로토콜을 제안한다.

• Nuclear Engineering and Technology
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• 제28권3호
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• pp.247-256
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• 1996

This paper presents a new approach for assessing accident management strategies using containment event trees (CETs) developed during an individual plant examination (IPE) for a reference plant (CE type, 950 MWe PWR). Various accident management strategies to reduce risk have been proposed through IPE. Three strategies for the station blackout sequence are used as an example : 1) reactor cavity flooding only, 2) primary system depressurization only, and 3) doing both. These strategies are assumed to be initiated at about the time of core uncovery. The station blackout (SBO) sequence is selected in this paper since it is identified as one of the most threatening sequences to safety of the reference plant. The effectiveness and adverse effects of each accident management strategy are considered synthetically in the CETs. A best estimate assessment for the developed CETs using data obtained from NUREG-1150, other PRA results, and the MAAP code calculations is performed. The strategies are ranked with respect to minimizing the frequencies of Various containment failure modes. The proposed approach is demonstrated to be very flexible in that it can be applied to any kind of accident management strategy for any sequence.

• 한국소음진동공학회논문집
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• 제17권6호
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• pp.484-490
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• 2007

A reciprocating compressor used in domestic refrigerators can be subjected to many different forms of shock. These shocks are usually experienced during transporting the products from a manufacturer to customers. The hermetic structure of this kind of compressor makes it difficult to conduct drop tests for identifying the failure mechanism and their drop behaviors. The drop/impact simulation for a reciprocating compressor has been carried out with the explicit code LS-DYNA and its validation has been experimentally verified. Simulation results are in good agreement with those of drop test. The present method of drop/impact simulation provides an efficient and powerful solution to improve the design quality and reduce the design period.

• Structural Engineering and Mechanics
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• 제10권2호
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• pp.165-180
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• 2000

An analytical model with tension softening for the prediction of the capacity of prestressed concrete beams under pure torsion and under torsion combined with shear and flexure is introduced. The proposed approach employs bilinear stress-strain relationship with post cracking tension softening branch for the concrete in tension and special failure criteria for biaxial stress states. Further, for the solution of the governing equations a special numerical scheme is adopted which can be applied to elements with practically any cross-section since it utilizes a numerical mapping. The proposed method is mainly applied to plain prestressed concrete elements, but is also applicable to prestressed concrete beams with light transverse reinforcement. The aim of the present work is twofold; first, the validation of the approach by comparison between experimental results and analytical predictions and second, a parametrical study of the influence of concentric and eccentric prestressing on the torsional capacity of concrete elements and the interaction between torsion and shear for various levels of prestressing. The results of this investigation presented in the form of interaction curves, are compared to experimental results and code provisions.

• Structural Engineering and Mechanics
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• 제19권3호
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• pp.237-260
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• 2005

This paper presents an experimental as well as a numerical analysis of the in-plane shear behaviour of hollow, $870{\times}840{\times}100mm$ masonry walls, externally strengthened with FRP composites. The experimental approach is devoted to the evaluation of the effectiveness of different composite strengthening configurations and the methodology consists in the diagonal compression of masonry walls. The numerical study assesses the stress and strain state distribution in the unreinforced and strengthened panels using a commercial finite element code. The effect of FRP reinforcement on the masonry behaviour and the capability of modelling to forecast a representative failure mode of the unreinforced and reinforced masonry walls is investigated.

• Wind and Structures
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• 제21권4호
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• pp.369-381
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• 2015

Moore, Oklahoma was hit by an EF5 tornado on May 20, 2013. The tornado track slightly overlapped with two previous tornadoes that occurred on May 3, 1999 and May 8, 2003 respectively. A research team from Texas Tech University was deployed to investigate the performance of shelters based on observation of their post-storm conditions. Sixty-one shelter units were further documented by size, manufacturer, and date of installation if available. Then they were crossed referenced with the external databases to determine their compliance with design and construction standards by the International Code Council/National Storm Shelter Association and/or criteria from the Federal Emergency Management Agency publications. Wind intensity was estimated for each shelter location using the EF scale. Results showed a marked increase in the number of exterior underground shelters as well as the popularity of a new in-garage floor underground shelter design. All of the units provided protection for their occupants with no loss of life reported. However, one older shelter had a door failure due to neglect of maintenance. Recommendations were made to improve future performance of shelters.

• Structural Engineering and Mechanics
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• 제56권2호
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• pp.317-340
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• 2015

Design codes have specified the minimum shear reinforcement requirement for reinforced concrete (RC) and prestressed concrete (PSC) members to prevent brittle and premature shear failure. They are, however, very different from one another, and particularly, ACI318 code allows the required minimum shear reinforcement to be reduced in PSC members, compared to that in RC members, by specifying the additional equation for PSC members whose basis is not clear. In this paper, the minimum shear reinforcement ratio for PSC members was proposed, which can provide a sufficient reserved shear strength and deformation capacity. The proposed equation was also verified by the test results of PSC specimens lightly reinforced in shear, comparing to design codes and other proposed equations from previous studies.