• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.37-46
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• 2004

This study was performed to establish valid methodology for determining dynamic stability(DS) of deformation-cycle curve which is obtained through wheel tracking(WT) test, the most widely used method for forecast of rutting tendency of asphalt mixture. Existing Korean and Japanese methods for DS are unrealistic and do not really reflect characteristics of rut resistance of asphalt concretes especially when the slope of deformation-cycle curve is stabilized at the end. It was proved that the new DS developed in this study reflected rut resistance characteristics better than existing methods. It is especially effective to distinguish the mixtures with high DR(depth of rut) but stable slope at the end of curve from the mixture with lower DR and continuous slope. The field evaluation must be followed to prove whether the mixture which shows a high DS value this method perform well in the filed.

• Journal of the Korean Geotechnical Society
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• v.38 no.9
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• pp.35-44
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• 2022

The cyclic triaxial strength test is commonly applied as a laboratory test for evaluating the liquefaction resistance ratio. However, the test procedure was not standardized in South Korea until recently; thus, the test results could significantly differ depending on the performer and apparatus, even when identical soil is used. In this study, the American and Japanese standards for the cyclic triaxial strength test were analyzed and the Korean standard was developed considering domestic circumstances. To verify the effectiveness of the standardization of liquefaction laboratory tests, several cases of cyclic triaxial strength tests were conducted and analyzed (1) following the Korean standard and (2) without following any specific instructions for the test procedure. Under (1), the deviation of the liquefaction resistance ratio dramatically decreased.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1996.10a
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• pp.406-409
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• 1996

• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.175-183
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• 1999

Recently, problems related to vibrations of decomposed granite soils have acquired increasing attention in Korea because those soils cover approximately one third of the country. Both resonant column and cyclic triaxial test were performed to investigate deformation characteristics of unsaturated and cement-mixed decomposed granite soils in Suwon region. The important soil parameters in this respect are the shear moduli, dynamic moduli of elasticity and damping ratios. The dynamic parameters are influenced by variables such as strain amplitude, ratio of loading cycles, and degree of saturations, etc. Test results and data have shown that the optimum degree of saturation to the maximum shear modulus due to a capillary menisci effect was about 17~18 % at low strain amplitude and 10~15 % at intermediate strain amplitude. This paper suggests the range of threshold strain and mean shear modulus of decomposed granite soils in Suwon region. It also proposed the empirical relationship between the dynamic parameters for cement-mixed and non-mixed decomposed granite soils.

• Geotechnical Engineering
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• v.11 no.1
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• pp.113-126
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• 1995

Both resonant column (RC) and torsional shear(TS) tests were performed at small to intermediate strain levels to investigate deformational characteristics of cohesive soils. The effects of variables such as strain amplitude, loading frequency, and number of loading cycles were studied. Plasticity index was found to be an important variables in evaluating these effects. Soils tested include undisturbed silts and clays and compacted subgrade soils. At small strains below the elastic threshold, shear modulus is independent of number of loading cycles and strain amplitude. Small strain material damping exists wi th ranges be tween 1.1% and 1.7% for 75 tests. The elastic threshold strain increases as confining pressure and plasticity index increases. Above the cyclic threshold strain, the modulus of cohesive soil decreases with increasing number of cycles while damping ratio is almost independent of number of load cycles. Moduli and damping ratios of cohesive soils obtanined by RC test are higher than those from 75 test because of the frequency effect. Shear modulus of cohesive soil increases linearly as a function of the logarithm of loading frequency.

• Journal of the Korean GEO-environmental Society
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• v.13 no.6
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• pp.5-17
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• 2012

The study of surface ground reinforcing method is supposed to be considered preferentially is not satisfied and also doesn't contemplate plastic flow because of repetitive drive of construction equipment. Also, Terzaghi's bearing-capacity equation and Yamanouchi's suggestion have been used to design the surface reinforcement, but most engineers depend on their experience and cases constructed before because of dispersed variables and inappropriate bearing-capacity factors. Hence, plate load test and repetitive plate load test were performed in the field which is reinforced with geotextile, Geogrid whose tensile strength are 200kN/m, 100kN/m and bamboo($0.4m{\times}0.4m$). The object of this study is to evaluate bearing capacity and behaviour of surface ground and to compare each reinforcement form test results. From the results bearing capacity ratio increased by a maximum of 1.5 times with bamboo reinforcement method comparing to others.

• Journal of the Society of Disaster Information
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• v.13 no.4
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• pp.491-498
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• 2017

The primary objective of this research is to develop a rutting performance prediction model of flexible pavement. Extensive laboratory testings were conducted to achieve the objective. A new test method employing repetitive axial loading with confinement was also adopted to estimate the rutting performance of asphalt concrete in the research. The rutting prediction model employes a layer-strain theory. The required rutting coefficients for the prediction model were determined through the laboratory rutting characterizations of the asphalt concrete layer materials. Within the limits of this study, a laboratory rutting prediction model of flexible pavement using repetitive axial loading test was presented. It is noted that the developed rutting prediction model simulates propery the behaviors of flexible pavement layer materials.

• The Journal of Engineering Geology
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• v.31 no.4
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• pp.493-506
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• 2021

Liquefaction refers to a phenomenon in which excessive pore water pressure occurs when a dynamic load such as an earthquake rapidly acts on a loose sandy soil saturated with soil, and the ground loses effective stress and becomes liquefied. The indoor repeated test for liquefaction evaluation can be confirmed through the repeated triaxial compression test and the repeated shear test. In this regard, this study tried to confirm the liquefaction resistance strength according to the relative density and particle size distribution of sand using the repeated triaxial compression test. As a result of the experiment, it was confirmed that the liquefaction resistance strength increased as the relative density increased regardless of the soil classification, and the liquefaction resistance strength according to the particle size distribution of the sand was confirmed that the liquefaction resistance strength of the SP sample close to SW was significantly higher. In addition, as a result of analyzing 30% of fine powder compared to 0% of fine powder, as the relative density increased to 40~70%, the liquefaction resistance strength decreased by 5~20%, and the domestic weathered soil ground had a fine liquefaction resistance strength compared to Jumunjin standard sand. When the minute was 10%, it was measured to be 30% or more, and when the fine particle was 30%, it was measured to be less than 50%.

• Journal of Korean Society of Steel Construction
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• v.10 no.4 s.37
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• pp.741-748
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• 1998

Experimental studies were carried out with test parameters: diaphragm yield type and beam yield type, the opening hole size of inner steel diaphragm, and the existence of slab in order to understand the behavior of beam-to-concrete filled steel tube column rigid connections under cyclic loading condition. Test results show that the connections have good rotational capacity when the beam yields first and the joints should be designed such that the beam yields prior to the inner diaphragms.

• Proceedings of the KIEE Conference
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• summer
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• pp.890-892
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• 2004

단락발전기를 이용하여 대전류 단락시험을 실시하는 시험 설비중 단락전류 투입시 정밀한 투입 위상각 제어와 주접점 접촉시 바운싱이 없는 투입개폐기 특성이 요구된다. 이러한 특성을 만족시키기 위하여 공압식, 모터식, 유압식등 여러 종류의 투입개폐기가 사용되고 있으며 Actuator와 주 접점 형상설계 및 조립기술에 의한 바운싱이 없는 제품 제작이 중요하다. 본 논문에서는 정격전압 24 kV 단락전류 47 kA, 통전시간 0.5 s의 투입용량과 연속 반복 투입시 $\pm0.1$ ms의 오차특성을 가진 정밀급 유압식 투입개폐기의 동작특성과 핵심부품 조사 및 바운싱 제거를 위한 대책실시와 반복시험을 통하여 투입개폐기 특성에 대한 연구를 목적으로 한다.