• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.2
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• pp.67-76
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• 2017

In this study, the effect of caisson heel on the active earth pressure is investigated. Using limit analysis method, inclinations of slip surface developed above the heel with different lengths are analyzed. The shorter the heel length, the larger those of inside slip surface, however those of outside slip surface are not changed. According to the relative heel length, relationships of internal friction angle of backfill material - wall friction angle between caisson structure and backfill - friction angle acting on virtual section at the end of heel are presented. Earth pressures acting against caisson structure with relatively short heel are smaller than Rankine earth pressure but always greater than Coulomb earth pressure which does not consider the heel length.

• Journal of the Korean Geotechnical Society
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• v.33 no.11
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• pp.59-72
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• 2017

In this study, the calculation method of the active earth pressure acting on the imaginary vertical plane at the end of the heel of the wall is proposed. For cantilever retaining wall, a change of shear zone behind the wall affects the earth pressure in the vertical plane at the end of heel of the wall depending on wall friction and angle of ground slope. It is very complicated to calculate the earth pressure by a limit equilibrium method (LEM) which considers angles of failure planes varying according to the heel length of the wall. So, the limit analysis method (LAM) is used for calculation of earth pressure in this study. Using the LAM, the earth pressures considering the actual slope angles of failure plane are calculated accurately, and then horizontal and vertical earth pressures are obtained from them respectively. This study results show that by decreasing the relative length of the heel, the slope angle of inward failure plane becomes larger than theoretical slope angle but the slope angle of outward failure plane does not change. And also the friction angle on the vertical plane at the end of the heel of the wall is between the ground slope angle and the wall friction angle, thereafter the active earth pressure decreases. Finally, the Coulomb earth pressure can be easily calculated from the relationship between friction angle (the ratio of vertical earth pressure to horizontal earth pressure) and relative length of the heel (the ratio of heel length to wall height).

• Journal of the Korean Geotechnical Society
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• v.34 no.10
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• pp.17-28
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• 2018

Important parameters for the stability checks of cantilever wall are the active earth pressure and the weight of soil above the heel of the base slab. If the heel length is so long enough that the shear zone bounded by the failure plane is not obstructed by the stem of the wall, the Rankine active condition is assumed to exist along the vertical plane which is located at the edge of the heel of the base slab. Then the Rankine active earth pressure equations may be theoretically used to calculate the lateral pressure on the vertical plane. However, in case of the cantilever wall with a short heel, the application of Rankine theory is not only theoretically incorrect but also makes the lateral earth pressure larger than the actual pressure and results in uneconomical design. In this study, for the cantilever wall with a short heel the limit analysis method is used to investigate the mechanism of development of the active earth pressure and then the magnitude and location of the resultants of the pressure and the weight of the soil above the heel are determined. The calculated results are compared with the existing methods for the stability check. In case of the cantilever wall with a short heel, the results by the Mohr circle method and Teng's method show max. 3.7% and 32% larger than those of the limit analysis method respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.594-601
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• 2019

A true MSEW abutment is an abutment type that directly supports the load of a superstructure. Metal strips, which are in-extensile reinforcements, should be used to minimize abutment deformation. A study to derive the application conditions of a True MSEW abutment was carried out by Zevogolis(2007). As a result, the pullout factor of safety of the uppermost reinforcement was estimated to be the smallest. Therefore, the pullout factor of safety of the uppermost reinforcement is the most important design factor. Parameter analysis was conducted with the abutment length, abutment heel, and abutment height as variables. The pullout factor of safety increased with increasing abutment length and abutment heel length. This is because the contact area increases and the superstructure is dispersed as the abutment length and abutment heel length increase. The pullout factor of safety converges at an abutment length of 1.2m and an abutment heel length of 0.9m. This is because the effective length of the reinforcement is reduced due to the increase in contact area. On the other hand, the extension of the superstructure will increase if the abutment length and abutment heel length are increased excessively. In addition, earth-volume is increased if the abutment height increases excessively. This acts as an upper load on the MSE wall. Therefore, it needs to be examined carefully.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.375-378
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• 2021

인간의 보행에는 다양한 분야에서 유용하게 사용할 수 있는 정보를 가지고 있어 의료분야와 수사기관에서 사용되고 있다. 보행 데이터로부터 유용한 정보를 얻어내기 위해 선행되어야 하는 작업은 보행주기를 판별하는 것이다. 본 연구에서는 보행주기 판별을 위하여 발 뒷굽 닿기와 발가락 떼기 행동을 가속도 값과 각속도 값을 사용하여 알아내고, 정확도를 분석하는 알고리즘에 대해 논한다.

• Geotechnical Engineering
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• v.14 no.2
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• pp.31-40
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• 1998

To verify the reinforcing effect of the strips which are inserted in the backfill, but not connected to the face wall, model tests are executed. As the reinforcing effect is expected to reduce the active thrust acting on the retaining wall, test programmes included the measurements of the thrust. As a result. it is ascertained that the active thrusts are reduced by as much as 50%. Besides, efficient arrangement and the optimum length of the strips are verified. And the the number of reinforcing strips are increased, are close to the Rankine's hypothesis.

• Journal of the Korean Geotechnical Society
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• v.30 no.4
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• pp.47-63
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• 2014

In this study theories of earth pressure such as Rankine, Coulomb, Trial Wedge, Improved Trial Wedge, used in the design for onshore and offshore structures, are analyzed and the characteristics of loaded pressure to virtual back (wall, plane) and wall surface in accordance with the structure type are suggested. To investigate characteristics of earth pressure, gravity retaining wall with inclined angle and cantilever wall with inclined ground are movilized for onshore structures and caisson and block type quay wall are mobilized for offshore structures. Based on various theories, the earth pressure applied angle(wall friction angle) and sliding angle toward the wall, which is influenced by the heel length, are calculated and compared. In the case of long heel, the pressure by Rankine's method in virtual plane and the mobilized angle are most reasonably estimated by the ground slope, and in the case of short heel, the pressure by Coulomb's method and the mobilized angle by the angle of wall friction. In addition, the sliding angle toward the wall estimated by the improved trial wedge method is large than the value of Rankine's method. Finally, in this study the reasonable method for calculating the pressure and the mobilized angle that can be applied to the routine design of port structures is proposed. The proposed method can decide the earth pressure with length of a heel and a self weight of retaining wall according to sliding angle toward the wall.

• The Journal of Korean Physical Therapy
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• v.25 no.2
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• pp.117-125
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• 2013

Purpose: The purpose of this study was to investigate changes in movement strategies of lower limb joints depending on the type of heel during sit-to-stand. Methods: Twenty healthy females participated in this study. All subjects performed sit-to-stand three times each with three different types of heels - bare feet, 9 cm high-heeled shoes, and unstable shoes. Trails were conducted in random order. Three-dimensional motion analysis systems were used for collection and analysis of the kinematic data of lower limb movements. Results: Results of this study showed kinematic differences in pelvis, hip joints, knee joints, and ankle joints during sit-to-stand based on the type of heels. At the initial sit-to-stand, hip joint flexion, knee joint flexion, ankle joint flexion, and ankle joint inversion showed significant differences. The maximal angles of hip joint flexion, hip joint adduction, knee joint flexion, ankle joint flexion, and ankle joint inversion were significantly different, while hip joint adduction, pelvic forward tilt, hip joint rotation, knee joint flexion, ankle joint flexion, and ankle joint inversion differed significantly during the terminal of sit-to-stand. Conclusion: Therefore, the type of heel played an important role in selection of lower limb movements during sit-to-stand which were essential parts of daily life movements.

• The Journal of Korean Physical Therapy
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• v.13 no.2
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• pp.467-475
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• 2001

The purpose of this study was to evaluate changes of static lumbar lordosis by different heel heights in normal adults and patients with herniation of nucleus pulposus(HNP). The lumbar lordosis was examined while standing on barefoot, on heel support with 4cm heel, and with 8cm heel in 10 normal adults and 10patients with HNP. Standing lumbar lateral view was performed by 20 minutes adaptation with corresponding shoe types. The angle of lumbar lordosis was taken with Wiltse and Winter's method(angles between upper margin of 1 st lumbar body and upper margin of 5th lumbar body). The results of this study were as follow: 1. Significant statistical decrease in lumbar lordosis was observed as heel heights were increased from barefoot to 8cm high heel in normal adults(p<0.05). 2. There were no significant differences in lumbar lordosis according to three different heel heights in patients with HNP(p>0.05). 3. In comparison of barefoot, There were statistically significant decrease in HNP patients compared with normal adults in terms of lumbar lordosis(p<0.05).

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.149-157
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• 2009

The purpose of this project was to determine biomechanical differences between Type A(Korean brand) and Type B(world top brand) badminton shoes and to make recommendations to improve the fit and function of Type A badminton shoes. Measurements of shoe shape and dimensions, foot movement within the shoe, cushioning of ground reaction forces, in-shoe pressure and outsole traction were performed. In addition, subjective feedback of the fit and function of the shoes was quantified for 17 recreational badminton players. Type A shoe had a much higher heel and shallower heel cup, so the heel was not secured well in the shoe and the ankle joint was higher off the ground. Foot slippage was up to 40% greater in Type A shoe than Type B shoe. Impact forces and peak pressures under the foot were generally higher with Type A shoe compared to Type B shoe. The flexion axis of Type A shoe occurred in the midfoot, not at the ball of the foot like Type B shoe, where you would want the shoe flexion to occur. In summary, there are several characteristics where A Type shoe and B Type differ. Therefore, a few recommendations are provided to help improve the fit and function of A Type shoe.