• Geomechanics and Engineering
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• v.18 no.5
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• pp.493-502
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• 2019

Internal stability is an important safety issue for levees, embankments, and other earthen structures. Since a large part of the world's population lives near oceans, lakes and rivers, floods resulting from breaching of dams can lead to devastating disasters with tremendous loss of life and property, especially in densely populated areas. There are some main factors that affect the internal stability of dams, levees and other earthen structures, such as the erodibility of the soil, the water velocity inside the soil mass and the geometry of the earthen structure, etc. Thus, the mechanism of internal erosion and stability of soils is very complicated and it is vital to investigate the assessment methods of internal stability of soils in embankment dams and their foundations. This paper presents an improved support vector machine (SVM) model to predict the internal stability of soils. The grid search algorithm (GSA) is employed to find the optimal parameters of SVM firstly, and then the cross - validation (CV) method is employed to estimate the classification accuracy of the GSA-SVM model. Two examples of internal stability of soils are presented to validate the predictive capability of the proposed GSA-SVM model. In addition to verify the effectiveness of the proposed GSA-SVM model, the predictions from the proposed GSA-SVM model were compared with those from the traditional back propagation neural network (BPNN) model. The results showed that the proposed GSA-SVM model is a feasible and efficient tool for assessing the internal stability of soils with high accuracy.

• Journal of Korean Physical Therapy Science
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• v.29 no.1
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• pp.55-63
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• 2022

Background: This study investigated the effect of erector spinae and quadratus lumbar kinesio taping and support surface conditions on abdominal muscle activity during plank exercise. Design: Within-Group design. Methods: A total of twenty-three healthy men and women participated in this study. Abdominal muscle (both external obliques and internal oblique muscle) contraction was analyzed through EMG measurement with the presence or absence of kinesio taping applied to the erector spinae muscle and quadratus lumborum muscle during plank exercise and the difference between the support surfaces (stable surface and unstable surface) as variables. Abdominal EMG was attached to the right external oblique, left external oblique, right internal oblique, and left internal oblique. Results: The results showed that Abdominal left and right external obliques and internal obliques showed significant increases in activity when kinesio taping was applied to the erector spinae and quadratus lumborum muscles and unstable ground (p<0.05). Conclusion: In this study, we confirmed that the activity of the abdominal muscles was significantly increased during the plank operation in the state where the kinesio tape was attached. In addition, it was confirmed that the activity of the abdominal muscles was significantly increased during the plank operation on the unstable surface. These results suggest that in the state of kinesio tape attached and instability, plank motion has a positive effect on abdominal muscle activity.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.1
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• pp.29-35
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• 2017

It was hard for a conventional care-bed to be realized to a low-floor position due to a complex actuation mechanism installed under the mattress support platform. In this paper a mechanism design to set a low-floor position as well as to adjust back- and leg-rest angles was proposed. A dual motor was applied to the back- and leg-rest mechanism of which design parameters were determined by an optimal method. An elevation mechanism was also designed to enlarge a limited stroke range up to two times of its original stroke using a pulley mechanism. An evaluation test was performed by five healthy subjects ($24.4{\pm}0.5yrs.$) when going up from a floor position to a preset best position which was set to the 240mm height for a prototype low-floor bed and to the 600mm height for a conventional bed. As a result, the moving distance was 38% lower than the conventional bed when the subject used the low-floor bed. It showed that the low-floor care-bed reduced physical burdens and was effective to assist activities of daily living of the elderly people.

• Journal of Korea Port Economic Association
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• v.20 no.2
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• pp.169-185
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• 2004

It is an urgent problem that Korea logistics enteprises' expansion of advance into China market and the logistics network establishment between Korea and China to back up the former are to be solved. Accordingly, the purpose of this study is to deduce the subjects to establish the logistics network between Korea and China, and to evaluate the priority order. The results of this research are as follows: First, we conducted face-to-face interviews on the advisery group in China and Korean enterprises which advanced into China, and drew out 6 promoting subjects to build the logistics network between the two. Second, the AHP model was adopted, which is a multi-criteria?multi-hierarchical decision making method, to draw out the weight and priority order of the deduced 6 promoting items. Third, the resultant priority order of the promoting subjects is as follows: No.1 - to establish the distribution & logistics support center by region(0.3900); No.2 - to support various taxes in investing the logistics business abroad(0.1980) ; No.3 - to improve the management of CIQ(0.1958); No.4 - to back up the joint-venture of logistics firms(0.1169); No.5 - to enhance trade and foreign policies to deregulate the entry into logistics markets(0.0536); No.6 - to construct the logistics information system of China(Northest Ssia)(0.0458). This paper resulted in finding out Korea logistics enterprises that have not secured their own inland-transport network in China and the actual difficulties of Korean enterprises with using the inferior network that advanced into China. These problems were developed into the analysis adopting the AHP method, and the significancy of this paper is to present the priority order of promoting problems using a sophisticated technique.

• The Transactions of the Korea Information Processing Society
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• v.4 no.1
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• pp.255-269
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• 1997

In this paper, we describe the implementation of C cross-compiler for the ES-C2340 DSP2 processor by using the GNU compiler. For the rapid and efficient developing of the compiler and other parts like the processor-dependent back -end which is implemented newly to build the compiler. This approach has several advantages. First, as we use GNU compiler's well-proved excellent optimization method and multi-language support capability, we can improve he efficiency and generality of the compiler. Second, as we concentrate on the high-level language as logic approving tool in processor developing process. And to support the cross-compiler, we also implement a text-level pre-linker.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.9
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• pp.1557-1563
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• 2016

According to recent studies, poor sitting posture of the spine has been shown to lead to a variety of spinal disorders. For this reason, it is important to measure the sitting posture. We proposed a strategy for classification of sitting posture using machine learning. We retrieved acceleration data from single tri-axial accelerometer attached on the back of the subject's neck in 5-types of sitting posture. 6 subjects without any spinal disorder were participated in this experiment. Acceleration data were transformed to the feature vectors of principle component analysis. Support vector machine (SVM) and K-means clustering were used to classify sitting posture with the transformed feature vectors. To evaluate performance, we calculated the correct rate for each classification strategy. Although the correct rate of SVM in sitting back arch was lower than that of K-means clustering by 2.0%, SVM's correct rate was higher by 1.3%, 5.2%, 16.6%, 7.1% in a normal posture, sitting front arch, sitting cross-legged, sitting leaning right, respectively. In conclusion, the overall correction rates were 94.5% and 88.84% in SVM and K-means clustering respectively, which means that SVM have more advantage than K-means method for classification of sitting posture.

• Physical Therapy Korea
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• v.9 no.2
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• pp.1-17
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• 2002

The purpose of this study was to identify the differences of the static and the dynamic balance reactions in the flexion syndrome (FS) and the extension syndrome (ES) group of the patients with chronic lowback pain (LBP) and healthy subjects. Twenty subjects were included in each group. By using EquiTest 5.02, the static balance was measured by the equilibrium score and the strategy score of sensory organization test (SOT), while the dynamic balance was measured by the latency of motor control test (MCT) and the sway energy of adaptation test (ADT). Oswestry Disability Index (OSI) was used to measure level of the disability in patients with chronic LBP. The equilibrium scores, the strategies of SOT, and thelatencies of MCT of three groups were compared with one way ANOVA, while the sway energy of ADT was compared with repeated measures one way ANOVA. The results of this study showed that the equilibrium scores and the strategy scores of SOT were significantly lower in patients with chronic LBP than in healthy subjects. The equilibrium scores and the strategy scores of SOT were significantly differences between the FS and ES groups in condition 5 (support surface was sway-referenced and visual information waseliminated by eye closure), and 6 (support surface was sway-referenced and visual information was altered by sway-referencing). The FS group showed delayed average reaction time at large posterior translation, however, the ES group showed delayed average reaction time at large anterior translation, Even though the sway energy of the patients with chronic LBP were greater than that of healthy subjects during the toe down (plantar flexion rotation), the values between the FS and ES groups didn't show any significant difference. The disability level showed highly correlation with the equilibrium score of the condition 5. As the results, the FS and ES groups divided by the their symptoms and signs in patients with chronic LBP showed different balance reaction. Therefore, more accurate evaluation and balance treatments are needed to focus on their symptoms and signs in patients with chronic LBP.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.1
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• pp.33-47
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• 2015

Concrete lining in tunnel construction is used as secondary support for downward loads when primary support decays. The use of concrete lining varies greatly depending on the intentions of engineer and/or client. An engineer uses much smaller deformation modulus which determines the concrete lining thickness than of a pattern 3, when supporting patterns 4 and 5 are used in a weathered rock and soil. Considering these conditions, this study intends to suggest optimal construction procedures through a back analysis using a computer program(MIDAS-civil). Cases of Seoul Subway System line${\bigcirc}{\bigcirc}$ zone${\bigcirc}{\bigcirc}$ were selected to be examined for this study. The results show that it is possible to reduce the thickness of concrete lining. When results from this study were applied to Seoul Metropolitan subway construction projects, it is expected to bring economic benefits.

• Journal of the Korean Geosynthetics Society
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• v.21 no.3
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• pp.49-59
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• 2022

This study was conducted to find out the rational and appropriate design of drilled shaft. In other words, in order to find out the variation of ultimate bearing capacity according to the change in the support layer of drilled shaft, back analysis was performed using the bi-directional pile load test performed on drilled shaft. Based on the back-analyzed data, numerical analysis of the pile head load was performed, and the ultimate bearing capacity in the target ground was evaluated using the Davisson method. As a result of numerical analysis of one case where the end of the pile was seated on the top of the weathered rock layer, and three cases where the end of the pile was embedded at different locations in the weathered soil, it was found that sufficient ultimate bearing capacity was secured in all cases. In other words, the case where the end of the pile is seated on the top of the weathered rock layer, not embedded the weathered rock, and the drilled shaft embedded into the weathered soil also have sufficient bearing capacity, so it can be used as a support layer for drilled shaft.

• Geomechanics and Engineering
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• v.27 no.6
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• pp.561-571
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• 2021

Cofferdams made of teel sheet piles are commonly utilized as support structures for excavation of sea-crossing bridge foundations. As cofferdams are often subject to tide variation, it is imperative to consider potential effects of tide on stability and serviceability of sheet piles, particularly, ultralong steel sheet piles (USSPs). In this study, a real USSP cofferdam constructed using new construction technology in Nanxi River was reported. The design of key parts of USSP cofferdam in the presence of tidal action was first introduced followed by the description of entire construction technology and associated monitoring results. Subsequently, a three-dimensional finite-element model corresponding to all construction steps was established to back-analyze measured deflection of USSPs. Finally, a series of parametric studies was carried out to investigate effects of tide level, soil parameters, support stiffness and construction sequence on lateral deflection of USSPs. Monitoring results indicate that the maximum deflection during construction occurred near the riverbed. In addition, measured stress of USSPs showed that stability of USSP cofferdam strengthened as construction stages proceeded. Moreover, the numerical back-analysis demonstrated that the USSP cofferdam fulfilled the safety requirements for construction under tidal action. The maximum deflection of USSPs subject to high tide was only 13.57 mm at a depth of -4 m. Sensitivity analyses results showed that the design of USSP cofferdam system must be further improved for construction in cohesionless soils. Furthermore, the 5th strut level before concreting played an indispensable role in controlling lateral deflection of USSPs. It was also observed that pumping out water before concreting base slab could greatly simplify and benefit construction program. On the other hand, the simplification in construction procedures could induce seepage inside the cofferdam, which additionally increased the deflection of USSPs by 10 mm on average.