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초연약지반의 지지력계수 N<SUB>c</SUB>에 관한 실험적 검토
함태규(Tae-Gew Ham),조삼덕(Sam-Deok Cho),양기석,유승경(Seoung-Kyoung You) 한국지반신소재학회 2012 한국토목섬유학회 학술발표회 Vol.2012 No.11
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 the design parameter for the surface ground improvement method. To that end, a wide width tensile test using geotextile, geogrid and steel bar (substitute for bamboo) and 25 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. And the result indicated that the modulus of subgrade reaction or Nc value (5.3) apparently overestimated the bearing capacity of very soft ground such as dredged ground.
ON THE INTIAL VALUE DEPENDENCE OF THE PROPER QUADRATIC FIRST INTEGRALS IN DYNAMICAL SYSTEMS
Rew, See-Gew 東國大學校 1988 論文集 Vol.27 No.-
1946년, T.Y.Thomas는 그의 著書를 통하여 古典力學系에 관한 固有2次 第1積分을 取扱한 以後 最近까지 物理學的이며 幾何學的인 意味를 解析하지 못하고 있는 실정이다. 1972년, M. Ikeda 및 Y. Nishino에 의하여 單純 力學系에 있어서 固有 2次 第2積分을 3가지의 類型으로 分類하고 있을뿐이다. 筆者는 本小考를 통하여, 運動의 trajectories에 着眼하여 初期値를 導入함으로 固有 2次 第1積分을 더욱 細分化하였을 뿐만아니라, 그 結果 物理學的으로는 Total energy는 初期値와 無關함을 밝혀보았다. 이와 같은 接近方法은 窮極的으로는 幾何學의 오랜 宿願이던, 一般的인 Killing tensor을 硏究하는데 도움이 되리라 믿는다. Although the problem of the proper quadratic first integrals has been treated by various author [1], [5], [6], etc., it remains open what is the meaning of the quadratic first integrals, We have focused our attention on this problem for a simple dynamical system in a 3-dimensional Euclidean space, mainly on the relations between the quadratic first integrals and the trajectories of a particle motion. M. Ikeda and Y. Nishino have classified the dynamical system treated here into the three Case Ⅰ, Ⅱ and Ⅲ. Among the proper quadratic first integrals, which contain 5 independent factors, but in CaseⅠ, there is no proper quadratic first integrals. There we led to consider the CaseⅡ and Ⅲ. In the present paper, we have further classified te proper quadratic first integrals with respect to the initial values of te trajectories. For the CaseⅢ, the proper quadratic first integrals exhibit a simple dependence of the initial position, but not of the initial velocity. Importance is the CaseⅡ, since we must consider the energy dependence when we treat the velocity dependence. We may say that among the quadratic first integrals the total energy is the only one that does not depent on any initial condition. Analysis treated here is closely related with the study of the general Killing tensors remains open in the meaning. Therefore, the present work has made a certain contribution to the above problem of the Killing tensors. The geometric and physical meaning of the proper quadratic first integrals have remained open for a long time. For the simple dynamical system as an illustration, it is shown that among the proper quadratic first integrals, someof them exhibit certain dependence on the inital values and the others do not. Therefore the proper quadratic first integrals can be classified into several classes with respect to the properties of the initial value dependence.
채기주(Key Gew Chae),박종현(Jong Hyeon Park) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
This paper proposes an optimal galloping trajectory which costs low energy and guarantees the stability of the quadruped robot. In the realization of the fast galloping, the trajectory design is important. As a galloping trajectory, we propose an elliptic leg trajectory, which provides simplified locomotion to complex galloping motions of animals. However, the elliptic trajectory, as an imitation of animal galloping motion, does not guarantee stability and minimal energy consumption. We propose optimization based on the energy and stability using a genetic algorithm, which provides the robust and global solution to a multi-body, highly nonlinear dynamic system. To evaluate and verify the effectiveness of the proposed trajectory, computer simulations were carried out.
연약지반 표층보강재의 인장강도와 복토두께의 지지력개선효과에 관한 실험적 연구
함태규(Tae-Gew Ham),조삼덕(Sam-Deok Cho),양기석,유승경(Seoung Kyoung You) 한국토목섬유학회 2008 한국토목섬유학회 학술발표회 Vol.2008 No.4
Engineering characteristics (tensile strength, sand mat stiffness, abrasion resistance) of surface reinforcements were evaluated and indoor model test was conducted to examine the influence of the engineering characteristics of surface reinforcements on the bearing characteristics of very soft ground strengthened with surface reinforcements. According to the outdoor exposure test with geotextiles and geogrid for 30 days, the strengths of materials reduced by less than 3.0% compared with the original specimen. Such small deterioration rate is within the product deviation and experimental error tolerance, therefore, judged to be negligible in the estimation of the strength reduction coefficient. According to the pull-out test results, the abrasion resistances between sand/geotextile/clay and sand/geogrid/clay were c=0.03㎏/㎠, φ=26.5˚ and c=0.02㎏/㎠, φ=22.0˚, respectively, and that of the geotextile was larger than geogrid by 1.2 ~ 1.5 times. According to the calculation, the bearing capacity ratios of geotextile according to the sand mat were 6.10, 7.78, and 11.1, at the sand mat of 0, 5㎝, and 10㎝, respectively, showing good correlation between the sand mat thickness of the casing soil and bearing capacity.
강성도에 주목한 표층처리공법으로 개량된 초연약지반의 지지력 산정방법
함태규(Tae-Gew Ham),조삼덕(Sam-Deok Cho),양기석,유승경(Seoung-Kyoung You) 한국토목섬유학회 2010 한국토목섬유학회 학술발표회 Vol.2010 No.11
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 the design parameter for the surface ground improvement method. To that end, a wide width tensile test using geotextile, geogrid and steel bar (substitute for bamboo) and 49 kinds of the laboratory model tests were conducted. And the result the study suggested β<SUB>s</SUB>, the stiffness coefficient to evaluate the stiffness effect of reinforcement materials. Then, it was also found that the stiffness coefficient, β<SUB>s</SUB> as the testing constant would be appropriate as high as 1.0, 1.1 and 1.5 for geotextile, geogrid and steel bar, respectively. And It was evaluated that the stiffness effect affecting reinforcement improvement effect would be reduced as the thickness of embeded depth increases and that RFe, the stiffness effect reduction coefficient would have positive correlation with H/B. Finally, it was confirmed that the bearing capacity gained from the method to calculate bearing capacity, which was suggested in the study, would almost correctly estimate the capacity, demonstrating the appropriateness of the proposed bearing capacity calculation method.