• Title/Summary/Keyword: 기초 강성

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Evaluation of the Optimal Vertical Stiffness of a Fastener Along a High-speed Ballast Track (고속철도 자갈궤도 체결구 최적 수직강성 평가)

  • Yang, Sin-Choo;Kim, Eun
    • Journal of the Korean Society for Railway
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    • v.18 no.2
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    • pp.139-148
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    • 2015
  • By increasing the vertical stiffness of the rail fastening system, the dynamic wheel load of the vehicle can be increased on the ballast track, though this increases the cost of track maintenance. On the other hand, the resistance acting on the wheel is decreased, which lowers the cost of the electric power to run the train. For this reason, the determination of the optimal fastener stiffness is important when attempting to minimize the economic costs associated with both track maintenance and energy to operate the train. In this study, a numerical method for evaluating the optimal vertical stiffness of the fasteners used on ballast track is presented on the basis of the process proposed by L$\acute{o}$pez-Pita et al. They used an approximation formula while calculating the dynamic wheel load. The evaluated fastener stiffness is mainly affected by the calculated dynamic wheel load. In this study, the dynamic wheel load is more precisely evaluated with an advanced vehicle-track interaction model. An appropriate range of the stiffness of the fastener applicable to the design of ballast track along domestic high-speed lines is proposed.

Evaluation of Dynamic Rock Stiffness Using In-hole Seismic Technique (인홀 탄성파 시험을 이용한 암반의 동적 강성 평가)

  • Sun Chang-Guk;Kang Byung-Soo;Kim Young-Su;Mok Young-Jin
    • The Journal of Engineering Geology
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    • v.15 no.3
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    • pp.309-323
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    • 2005
  • Dynamic stiffness of subsurface materials is one of the most important geotechnical parameters in predicting deformational behavior of structures as well as practicing seismic design and performance evaluation. In an effort to measure the parameter efficiently and accurately, various borehole seismic testing techniques have been, thus, developed and used during past several decades. Moreover, recent rush of underground-space projects and increasing size of structures put more stress on reliable site investigation techniques in estimating stiffness of rock mass. In this paper, a new technique called 'in-hole seismic test' has been implemented to measure the dynamic stiffness of rock masses at subsurface foundations and tunnel-faces. The reliance of in-hole seismic test was evaluated by comparing the testing results at several rock sites with those of other borehole techniques and the technique tunnls out to be an efficient and accurate in-situ testing technique.

A Study on Bearing Capacity Evaluation Method of Surface Reinforcement Method for Soft Ground in Consideration of Stiffness (강성도를 고려한 연약지반 표층처리공법 지지력산정방법에 관한 연구)

  • Ham, Tae-Gew;Seo, Se-Gwan;Cho, Sam-Deok;Yang, Kee-Sok;You, Seung-Kyong
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.1118-1125
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    • 2009
  • This study, as basic research which was intended to develope the surface reinforcement method using reinforcement material which is applicable to very soft ground in Korea, was aimed at proposing Bearing Capacity Evaluation method for the surface ground improvement method. To that end, a wide width tensile test using geotextile, geogrid and steel bar (substitute for bamboo) and 21 kinds of the laboratory model tests with the end restraint conditions of the reinforcement that comprises the constrained and partially constrained (3 types) conditions were conducted. According to result of tests, Terzaghi's bearing capacity method is adequate to calculate bearing capacity in non-stiff material(geotextile, geogrid). But, It can't adequate to stiff material(bamboo net). So, New bearing capacity method suggest surface reinforcement method of very soft ground which Terzaghi's bearing capacity method modify for effect of stiffness.

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A Study on Displacement Effect of Different Foundation using Concrete and Rubble (콘크리트, 잡석에 의한 이질기초 치환효과에 관한 연구)

  • Lim, Hae-Sik;Park, Yong-Boo
    • Land and Housing Review
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    • v.2 no.2
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    • pp.189-194
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    • 2011
  • To reinforce bearing capacity-changed section or different foundation in the same building, empirical or simple tools have been used. To solve this problem, we suggest the analytical solution that can evaluate and reinforce the stability of foundation. To estimate the effect of reinforcement by replacement in different foundation, soil stiffness evaluation method taking into account the influence factor with respect to depth beneath the foundation need to be applied. In this paper, graphs and relevant formulae are suggested to calculate equivalent soil reaction coefficient showing the effect of reinforcement by crushed stone and lean concrete replacement.

A Study on Comparison of Finite Element Analysis with Model Test of Shallow Footing Failure for Cohesionless Soil with Non-associated Plasticity and Some Smooth Footing (사질토지반의 지지력분석을 위한 얕은기초의 파괴거동에 대한 모형실험과 유한요소해석 비교 검토)

  • Kim, Young-Min;Kang, Sung-Wi
    • Journal of the Korean Geosynthetics Society
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    • v.9 no.1
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    • pp.13-20
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    • 2010
  • This paper describes the procedure to predict the entire load-displacement curve and the failure mechanism of shallow strip footing for real soil. The presented results show that it is possible to analyze the post peak behavior of shallow strip footing and to give a progressive failure mechanism clearly. Finite element computation of the bearing capacity factor $N_{\gamma}$ have been made for shallow strip footings with friction angles and dilation angle. It is shown that commonly used values of $N_{\gamma}$ which have generally been based on associated plasticity calculations are unconservative for real soil with non-associated plasticity and some smooth footing.

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Strength and rigidity test of a small sedan body (승용차 차체의 정적 강도 및 강성시험)

  • 박광남;박성현
    • Journal of the korean Society of Automotive Engineers
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    • v.3 no.1
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    • pp.32-37
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    • 1981
  • 모든 차형을 간단한 이상형으로 가정하여 그들을 수치적인 값으로 비교할 수 있다면 승용차 차 체의 설계상 매우 큰 도움이 될 것이다. 실제로 새로운 모델의 차가 개발되었을 때에는 다음과 같은 이유 때문에 그 prototype body에 대한 정적 시험이 실시되고 있다. 1) 조기에 설계의 문제점이나 차체의 주결함을 발견할 수 있어 시간과 경비를 절약할 수 있다. 2) 계속적인 정적 시험을 통하여 구조적으로 만족할 만한 road car를 만들 수 있다. 3) 과설계를 방지하여 차체의 경량화에 기여하고, 최적설계의 개발을 위한 길을 제시해 준다. 차체에 대한 정적 시험은 위와 같은 이유 때문에 발전되어 왔으며, 정적 시험의 효과를 ㅊ대로 하기 위하여 그것은 순수한 공학적 원리에 기초를 두어 실제의 사용조건과 충분히 일치되는 시 험으로서 고안되었다. 차체구조는 그 사명의 다양성뿐만 아니라 제작, 개수에 상당한 노력과 시 간이 필요하기 때문에 조기에 문제점을 발견하여 결함을 제지하지 않으면 안된다. 구조체로서의 많은 필요조건 중에서 특히 중요시되는 것은 강도, 강성 및 내구성이다. 그 때문에 차체의 강도, 강성시험은 이론적인 해석(탄성학, 구조역학, 강도학 등)에 앞서 여러가지 방법이 개발되어 왔 으며, 여기에서는 그 중 가장 대표적인 방법인 비틀림시험(torsion test)과 굽힘시험(bending test) 에 관하여 Pony 4-door Sedan 차체의 시험 결과를 토대로 하여 기술하고자 한다.

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Analysis of in Pipeline Systems Using Rigid Water Colum Model (강성수리 모델에 의한 파이프라인계의 서어징 해석)

  • 김선주
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.32 no.1
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    • pp.87-102
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    • 1990
  • 개방식과수로는 낮은 압력으로 다량의 용수를 수송할 수 있는 장점을 갖고 있으나 유량변동에 의한 서어징현상이 현저한 것이 단점이다. 관로내의 흐름을 안정시키기 위해서는 이 서어징의 특성이 규명되어 대규모의 서어징에 대한 대책이 강구되어야 할 것이다. 개방식관수로계의 서어징을 강성수주이론으로 계산하기 위하여 운동방정식 연속방정식가 스탠드 수조의 중간벽에 설치된 언의 월유공식등을 조합한 기초방정식이 유도되었다. 본 연구의 수치해석 모델은 가장 일반적인 4차의 Runge-Kutter 방법을 사용하였으며, 이 모델의 정당성과 프로그램의 유통성을 검증하기 위하여 수리모형실험치와 수치해석치가 비교되었다. 그 결과 관로에 공기의 혼입이 없는 경우에는 실험치와 해석치가 실용상의 지장이 없는 정도로 잘 일치되었지만, 공기의 혼입이 발생되는 경우에는 실험치가 해석치에 비해 약간 크게 나타나서 이 경우에도 서러징의 해석이 가능한 새로운 모델의 개발이 필요한 것으로 생각된다. 또한 본 강성수주 모델을 이용하여 현재 서어징 문제로 곤란을 받고 있는 일본 자하연 비파호 부근의 용수간선을 대상으로 그 서어징의 특성과 개선방법을 경계한 결과 개설 개방식관수로계의 스탠드 중 매3개소 스탠드마다 1개소 스탠드의 하류측 수조 수면적 확장하는 것이 타당성이 있는 것으로 해석되었다.

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An Analysis Method of Large Structure Using Matrix Blocking (블록화기법을 이용한 대형구조물의 해석방법)

  • Jung, Sung-Jin;Lee, Min-Sup
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.2
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    • pp.30-37
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    • 2014
  • In this study, we studied how to perform the structural analysis which need a large-capacity flash memory with the computer program when the flash memory storage of a personal computer has no enough room for the analysis of structure. As one of the solutions of this problem, the blocking method of stiffness matrix, which is a method that stiffness matrix is divided by a few blocks and each block is sequentially used for the calculation of matrix decomposition, is proposed and an algorithm available in computer program is derived on the method. Finally, A structural analysis program (sNs) based on this study is developed and the correctness and efficiency of the algorithm is founded through some examples which are fundamental in structural analysis.

Identification of Stiffness and Damping Matrix of Building Structures using Modal Characteristics (모드 특성을 이용한 건축 구조물의 강성 및 감쇠 행렬식별)

  • 강경수
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.2
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    • pp.45-53
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    • 2004
  • In this paper, the stiffness and damping matrix are experimentally constructed using the structural modal information on frequencies, damping ratio and modal vectors, which are obtained by shaking table tests. Free vibration, harmonic and white noise vibration tests are performed. The acceleration of the shaking table was used as the input signal, and the corresponding accelerations of each floor were measured as output signals. The characteristics and limitations of modal information from each test are compared. The results of this study would be a basic resource of the analytical and experimental studies on the system identification of structures.

A Study on Optical Experiments using Computer Interface (컴퓨터 인터페이스를 이용한 광학실험에 관한 연구)

  • Kang, Sung Soo
    • Journal of Korean Ophthalmic Optics Society
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    • v.7 no.2
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    • pp.73-77
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    • 2002
  • Applying the computer interface cards installed to old-fashioned, used PENTIUM I for the basic optical experiment makes students to have more attention and interests in the experiment, and enhanced the accuracy of the optical experiment. When applied for the light diffraction experiment, the above way of results made the experiment more accurate comparing with those of other experiments operated in advance. In addition, they turned out to be as same as the data in theory. Applying the above way not only for the basic optical experiments to recycle old-fashioned PCs being abandoned but also for the automation of optical experiments in manual could enhance the efficiency of the experiment a lot.

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