• Magazine of the Korea Concrete Institute
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• v.9 no.6
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• pp.185-193
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• 1997

본 연구는 각종 제진재료를 이용하여 진동을 억제할 수 있는 콘크리트를 개발하여 각종 건설공사에서 흔히 발생할 수 있는 진동공해문제를 억제하고자 하며 아울러 폐기물의 재활용차원에서 폐자재를 이용하여 유용한 제진콘크리트를 개발하고자 하는데 그 목적이 있다. 우선, 제진재료를 이용한 압축강도 (200kg/$\textrm{cm}^2$)이상의 콘크리트 배합비를 찾기 위하여 24배치의 예비실험을 수행하였으며, 선정된 적정배합비에 따른 제진재료를 이용한9개의 진동시험체보를 제작하여 보의 구조적 및 재료적 동적특성 즉 1차 공명진동수와 동적 휨강성 및 감쇠비를 측정하여 제진효과를 조사하였다. 그리고 압축강도에 의한 각 시험체의 균열모멘트를 추정하여 재하하중과 균열모멘트비(M/Mcr)에 따른 하중단계별 동적특성값을 살펴보았다. 제진재료로서는 라텍스(Latex), 고무분말(Rubber Powder)그리고 플라스틱 레진( Plastic Resin)등을 사용하였고, 재료적, 구조적 진동감쇠효과를 파악하고자 KS F2437규정과 진동파의 속도법을 사용하였으며, 감쇠비 측정은 Frequency Spectrum 곡선에 대한 Polynomial Curvefitting 방법과 기하학적 해석방법을 이용하여 각각의 결과를 비교.분석하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.96-106
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• 2014

The increased vibration level of the railway bridge could make significant noise and, also, cause structural damages such as fatigue cracks. Related to these subjects, a spherical elastomeric bridge bearing, which is layered by hemispherical rubber and steel plates, was investigated in terms of its vibration performance. Several different shape factors could be considered by changing the curvature of hemispherical surface and size in rubber and steel plate thicknesses in the manufacturing stage. The performance of the spherical elastomeric bearing for the reduction in vibration was compared with that of the conventional bearing by performing vibration experiments on a scale-downed model. The rubber material characteristics and spherical shape are found to be important parameters in reducing the bridge vibration.

• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.95-105
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• 2000

Anisotropy of stiffiness, from extremely small strains to post-failure strains, of isotropically consolidated air-pulviated sands in plane strain compression was studied by using the newly developed instrumentation for small strain measurements. Seven types of sand of the world-wide origins were tested, which have been extensively used for research purposes. Stress-strain relationships for a wide range of strain from about 0.0001% to 10% were obtained with measuring axial and lateral strains locally free from the effects of bedding and membrane penetration errors at the specimen boundaries. It was found that the maximum shear modulus Gmax was irrespective of the angle $\delta$of the $\sigma$1 direction relative to the bedding plane. However, the normalized Gmax was varied with the types of sand. Furthermore, the dependency of the strain and stress level on the stiffness increased as decreased.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.198-203
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• 2017

This study observed the effects of auxetic mesh reinforcement in concrete on the mechanical characteristics under compression. Series of double arrow type 2-D auxetic mesh were manufactured and embedded into concrete specimens. Compression tests were performed and results showed that the application of auxetic mesh as concrete reinforcement can restrain the deformation of concrete resulting in the enhancement of stiffness of composites.

• Geotechnical Engineering
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• v.4 no.4
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• pp.29-38
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• 1988

One of the main objectives of researches for the chemical grouting is to assess the changes in soil properties caused by injection of chemical grout. Especially the changes in the strength properties of soils, such as elastic modulus, shear modulus of ground due to injection of chemical grout has drawn our attention. Since the specific surface changes with variation in the grain size of sandy soil, the influence of grain size of sandy toil on the strength and stiffness of silicate-grouted soil was investicated in this study by earring out uniaxial and triaxial compression tests. It was found that the strength and stiffness of grouted soil increased as the grain size of sandy soil decreases, the possibility of estimating the strength of grouted soil was confirmed through the study of relationship between specific surface of sandy soil and the strength of chemical gel.

• Journal of the Korean Geosynthetics Society
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• v.5 no.4
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• pp.19-25
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• 2006

To examine the general features of a sand-clay composite triaxial test by making specimen varying ratios of diameters (dw) of sand columns that are installed on the soft ground as drains to diameters (de) of drain zone so called drainage space ratio (n=de/dw), densities of the granular columns, and strength of soft soils round around. I also conducted a test to research the reinforcement ability and effects of the ground when the granular columns are wrapped with supplementary materials such as geotextile. The results of the triaxial compression test showed that the shear strength increase is much big when the granular columns are wrapped with supplementary materials, while the shear strength increases as the diameter and density of the granular column increase in general. Also the drainage space ratio shows a distinct increase just below 3 and a similar shear behavior to sand is appeared. The pore water pressure coefficient decreases as the drainage space ratio decreases, however, when the drainage space ratio is less than 3~4, it declines significantly as shown in the results of shear behavior.

• Journal of the Korean GEO-environmental Society
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• v.16 no.6
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• pp.31-38
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• 2015

Recently, the participation on the development of the natural gas pipeline in Russia as well as the recent construction of the second Korean Antarctic research station, the Jangbogo station provide the research interests on the behavior of the permafrost ground. To investigate the effect of fines on the mechanical responses of frozen sands, unconfined compression tests were performed on the frozen sands with 0, 5, 10 and 15% of fine contents at -5, -10 and $-15^{\circ}C$. The poorly graded (SP) Joomunjin sand and kaolinite, silt with low plasticity (ML) were used for the preparation of the frozen soil specimens. The mechanical responses of the tested soils were investigated via unconfined compression tests in the temperature controlled laboratory and analyzed in terms of peak unconfined compressive strength and secant modulus at 50% of the peak strength. As the fine contents increase, the unfrozen water contents increase and thus the strength and stiffness of frozen soils decrease. The increment of the stiffness and strength due to the temperature decrease vary with the fine contents.

• Magazine of the Korea Concrete Institute
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• v.11 no.1
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• pp.191-200
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• 1999

The shear behavior of simply supported reinforced concrete deep beams subject to concentrated loads has been scrutinized experimentally to verify the influence of the structural parameters such as concrete strength, shear span-depth ratio, and web reinforcements. A total of 42 reinforced concrete deep beams with compressive strengths of 250 kg/$cm^2$ and 500 kg/$cm^2$ has been tested at the laboratory under one or two-point top loading. The shear span-depth ratio have been taken as three types of 0.4, 0.8 and 1.2, and the horizontal and vertical shear reinforcements ratio, ranging from 0.0 to 0.57 percent respectively. In the tests, the effects of the shear span-depth ratio, concrete strength and web reinforcements on the shear strength and crack initiation and propagation have been carefully checked and analyzed. From the tests, it has been observed that the failures of all specimens were due to shear and the shear behaviors of specimens were greatly affected by inclined cracks from the load application points to the supports in shear span. The load bearing capacities have changed significantly depending on the shear span ratio, and the efficiency of horizontal shear reinforcements were increased as the shear span-depth ratio decreased. The test results have been analyzed and compared with the formulas proposed by previous researchers and the design equation from the code. While the shear strengths obtained from the tests showed around 1.4 and 1.9 times higher than the values calculated by CIRIA guide and the domestic code, they were closely coincident with the formulas given by de Paiva's equation.

• Journal of the Korean GEO-environmental Society
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• v.13 no.2
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• pp.95-102
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• 2012

In this study, practical verifications for an advanced C.I.P(Cast in Place Pile) construction method were carried out. The structural characteristics of the method is to attach an angular joint in the steel-casing. This joint plays an important role in boring vertically, connected pile to pile, and protects the permeation of the ground water. For verifications, experimental research and numerical analysis were performed. In the experimental research, two model-tests were set up with the real scale steel-casing. One is to examine the leakage in the joint of piles and the other is to compare earth pressures in the front and the joint, respectively. In addition, 3 point bending test and compressive loading test were carried out and numerical analysis was performed to simulate the loading test. As a result of model-tests, the leakage in the pile joints was not shown up to 300 KPa of water pressure and stress concentration in the joint is out of the question. From the results of bending and compressive test, it was found that the new advanced C.I.P method is more convenient and superior than the conventional method.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.228-231
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• 2005

본 연구는 지하수를 생활용수로 활용하기 위한 시설물로 검토되고 있는 지하댐을 건설함에 있어 유력한 공법으로 제안되고 있는 SCW(Soil Cement Wall) 차수벽 설계지침을 마련하기 위하여 수행된 시험결과이다. 실험을 통해 SCW 각 혼합재료의 함유율에 따른 일축압축강도와 차수벽체의 강성을 나타내는 평균탄성계수를 산정하였으며, 혼합재료의 함유율과 양생조건을 조절하면 지하댐과 같은 구조물에 최적의 조건이라고 할 수 있는 고강도 저강성 벽체의 구현이 가능하다는 것을 확인하였다.