• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.2
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• pp.161-169
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• 1999

이방성체의 평면내 직선균열에 대한 균열선단부근의 응력과 변위의 분포는 어떠한 균열체의 형상 및 하중조건에 대해서도 응력확대계수라는 하나의 매개변수로서 나타낼 수 있다고 하는 것이 파괴역학에서 보편화되어 있다. 그러나 많은 경우에 있어서 급수전개식의 이어지는 항은 정량적으로 중요하다. 따라서 본 연구에서는 이러한 항을 유도하고 이것이 균열진전방향에 미치는 영향에 대하여 검초하였다. 이를 위하여 단축하중을 받는 직방성균열체의 해석을 수행하며 재료는 균질이방성체라고 가정하였다. 급수전개식에서 2차항의 영향을 고려하기 위하여 균열선단에서의 응력의 분포를 재해석하였으며, 2차항의 사용은 정확한 균열진전방향의 결정을 위해서 매우 중요함을 보였다. 초기균열진전각도의 결정을 위해서 수직응력비이론을 적용하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.3
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• pp.217-226
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• 2003

This study is focused on the finding out load transfer mechanism in the ground near the tunnel during tunnel excavation in the jointed sandy ground. Laboratory model tests were performed on various cases of the overburden heights above tunnel crown, location, and degree of discontinuity planes. For model tests, a movable plate was installed in the midst of the bottom of sandy ground. This plate, moving downwards, was intended to model the stress relaxation during tunnel excavation. The load transfer was measured at the fixed separated bottom plates adjacent to the movable plate. As the result, the loosening zone and the load-transfer form around the tunnelling site were affected by the overburden height and the characteristics of discontinuous planes. And large loosening zone was developed along the discontinuous planes which were close to the tunnel.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.3
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• pp.63-70
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• 2010

We are able to find many materials of pendulum dynamic/analysis using linearized model. Usually, analysis of pendulum is to calculate for velocity, period and angle by linearized model on Newton's law. In this paper, analyzed periodical movement of pendulum using nonlinear load model. That is, analyzed load value according to location of moving pendulum at real time. And for the shake of maneuver for pendulum's location, found load control value and compared result of linearized mode with nonlinear model. The result makes know that it is possibility of nonlinear load control model to apply to various model of movement object including flight object, pendulum and etc.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.837-838
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1253-1254
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• 2011

• International Journal of Highway Engineering
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• v.10 no.3
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• pp.79-86
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• 2008

This paper proposed the appropriate installation angle of skewed sensors for measuring vehicle wandering data, which are collected to figure out the location of dynamic weight of a moving vehicle on roadways. We developed a device using tape-switch sensors and a computer program and collected vehicle wandering data with the device and probe vehicles. As a result, the steeper the skewed sensor was installed, the lower the error was shown. However, we could not collect proper data when a skewed sensor was set up higher than $30^{\circ}$ due to tandem axle. Therefore, this study suggested the appropriate angle of skewed sensors as a degree of $20^{\circ}$ to $25^{\circ}$ for gathering wandering data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.21-28
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• 2017

Electro-hydraulic sliding deck systems have been developed to reduce the weight for the loading of an agricultural machine. The extension length of the sliding deck was calculated according to the bed's dump angle. The optimum thickness and material were determined using a large and heavy load at acceptable angles. In addition, the degrees of freedom were calculated to obtain the input/output relationship of the system. An equation was derived using a simplified model formula for the extended length of the sliding deck according to the bed's dump angle. Also, the advance length at the maximum and minimum angles of the system was determined using numerical analysis. A down-scaled model of the system was constructed and verified by experiments. The deck was simplified to determine the material and thickness of the sliding deck and for the selection of the two representative materials. The simplified model was tested in deformation tests and stress tests with different thicknesses and materials using a structure analysis program. The analysis results show that ATOS80 is the best among the two materials for reducing the weight of the system.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.36-43
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• 2010

In this study, the buckling loads and mode shapes characteristic of circular and non-circular(elliptical) closed composite shells were analyzed. To analyses the buckling behaviors, we develop and report an improved generalized shell element called 4EAS-FS through a combination of enhanced assumed strain and the substitute shear strain fields. A flat shell element has been developed by combining membrane element with drilling degree-of-freedom and a plate bending element. The combined influences of length, thicknesses, cross-sectional parameters, and fiber-angle on the critical buckling loads and mode shapes of circular and non-circular(elliptical) closed shells are examined.

• Tunnel and Underground Space
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• v.21 no.4
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• pp.307-319
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• 2011

Cyclic loading due to traffic, excavation and blasting causes microcrack growth in rocks over long period of time, and this type of loading often causes rock to fail at a lower stress than its monotonically determined strength. Thus, the crack growth and coalescence under cyclic loading are important for the long-term stability problems. In this research, experiments using gypsum as a model material for rock are carried out to investigate crack propagation and coalescence under monotonic and cyclic loading. Both monotonic and cyclic tests have a similar wing crack initiation position, wing crack initiation angle, cracking sequence and coalescence type. Three types of crack coalescence were observed; Type I, II and III. Type I coalescence occurs due to a shear crack and Type II coalescence occurs through one wing or tension crack. For Type III, coalescence occurs through two wing or tension cracks. Fatigue cracks appear in cyclic tests. Two types of fatigue crack initiation directions, coplanar and horizontal directions, are observed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.1
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• pp.38-51
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• 1984

Mononobe-Okabe에 의해서 옹벽에 대한 동적 토압계산법이 개발된 이래 본론두중 옹벽의 과동에 의한 변위에 대해서는 많은 연구가 이루어졌으나 Mononobe-Okabe식이 원래 옹벽 자체의 관성을 고려치 아니하였고 또 동적 하중의 작용점을 제시하지 않으므로서 전도모멘트를 계산할 수 없게 하므로서 옹벽의 전도에 의한 변위에 대해서는 연구가 되지 아니하였다. 본 연구의 목적은 해석적 방법과 모형실험을 통해서 지진 및 폭파 등의 동적 하중에 의한 옹벽의 전도에 의한 변위를 고찰하고자 하는 바 그 결과를 요약하면 다음과 같다. 1. 활동에 대한 항복가속도가 있는 것과 마찬가지로 전도에 대한 항복가속도가 있다. 이 항복가속도는 옹벽의 안전율이 증가함에 따라 증가한다. 2. 이론치와 실험치는 경향으로 보아 일치한다. 실험치가 이론치보다 작은 것은 모형실험에서 옹벽측면과 컨테이너 사이의 마찰에 기인한 것으로 보아지며 마찰을 줄임으로써 이론치에 더 접근시킬 수 있을 것이다. 3. 옹벽의 회전각도의 크기는 지반가속도가 클수록, 옹벽저면이 작을수록 그리고 흙의 내부마찰각이 작을수록 크게 증가한다. 4. 실용적인 규격의 옹벽의 변위는 활동에 의한 것보다 전도에 의한 것이 훨씬 크며 전체 변위의 대부분을 차지한다. 5. 옹벽 상단의 횡적 변위는 옹벽 설계를 결정짓는 중요한 요소가 될 수 있다.