• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.285-298
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• 2003

Shear properies of geosynthetic/geosynthetic and geosynthetic/soil interfaces which are widely met in landfill sites were evaluated from the inclined board tests. The inclined board testing apparatus is known to reproduce the shear behavior on the low normal stress most accurately. In this study, the friction angle of each interface was estimated and the tensile force mobilized at the geosynthetic was measured as well. The test results showed that the friction angle of each interface and the tensile force of the geosynthetics depended on the amount of normal stress, the type of the geosynthetics used, and the combinations of geosynthetics and soils. In addition, the sand/geotextile/geomembrane interface system was simulated in this study, and it was observed that the tensile force developed at the geomembrane decreased due to the protection effect of the geotextile located above the geomembrane. The test results of this research was compared with those of direct shear tests published, too. Finally, by comparing the measured tensile force of the geosynthetics when the initial displacement of the box occurs, when the slope is called as the critical slope, with suggested analytic solution, the accuracy of analytic solution and the applicability to design were identified.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.356-363
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• 2004

In this research, the shear behavior of four different interfaces consisting of 4 types of geosynthetics was examined, and both static and dynamic tests for the geosynthetic interface were conducted. The monotonic shear experiments were performed by using an inclined board apparatus and large direct shear device. The interface shear strength obtained from the inclined board tests were compared with those calculated from large direct shear tests. The comparison results indicated that direct shear tests are likely to overestimate the shear strength in low normal stress range where direct shear tests were not performed. Curved failure envelopes were also obtained for interface cases where two static shear tests were conducted. By comparing the friction angles measured from three tests, i.e. direct shear, inclined board, and shaking table tests, it was found that the friction angle might be different depending on the test method and normal stresses applied in this research. Therefore, it was concluded that the testing method should be determined carefully by considering the type of loads and the normal stress expected in the field.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2C
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• pp.73-80
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• 2006

The shear behavior of four different interfaces consisting of four types of geosynthetics was investigated, and both static and dynamic test for the geosynthetic interfaces were conducted. The monotonic shear experiments were performed by using an inclined board apparatus and large direct shear device. The interface shear strength obtained from the inclined board test was compared with calculated values from large direct shear tests. The comparison results indicated that direct shear tests show high possibility to over-predict the shear strength in the low normal stress range where direct shear tests are not performed. Curved failure envelopes were also obtained for interface cases where two static shear tests were conducted. By comparing the friction angles measured from three tests, i.e. direct shear, inclined board, and shaking table test, it was found that the friction angle might be different depending on the test method and normal stresses applied in the research. Therefore, it was concluded that the testing method should be determined carefully by considering the type of loads and the normal stress expected in the field with using the geosynthetic materials installed in the site.

• The Journal of Korean Physical Therapy
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• v.22 no.2
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• pp.47-53
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• 2010

Purpose: This study investigated the effect of electroacupuncture stimulation on changes in blood biochemistry in spinal cord injury (SCI) rats whose cords were damaged by 6-hydroxydopamine (6-OHDA). Methods: Twenty-one Sprague-Dawley adult male rats were assigned to one of three groups: normal (n=7), control (n=7) and experimental group (n=7). The experimental group received electroacupuncture (Es-160, ITO, Japan) for 15 minutes in the form of low frequency (2 Hz) stimulation to the zusanli point. After treatment, we observed motor behavior recovery using the inclined plane test. We also measured serum and CNS concentrations and activities of enzymes including creatine kinase (CK), alkaline phosphatase (ALP), and Immunoglobulin G (IgG). Statistical analysis was done using one-way analysis of variance (ANOVA). Results: Concentrations of CK, ALP and IgG were lower in the experimental group than in the control group. Functional recovery was evaluated by the maximal angle of the inclined board on which rats could maintain their initial position. This allowed us to monitor progressive locomotor recovery. The maximal angles of the inclined plane test were higher in the experimental group than in the control group (p<0.05). Conclusion: The results of this study showed that electroacupuncture to the zusanli point has a therapeutic effect on functional recovery after SCI.

• The Journal of Korean Physical Therapy
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• v.19 no.3
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• pp.1-9
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• 2007

Purpose: Previous studies have suggested that BDNF has a role in plasticity and survival following spinal cord injury and treadmill exercise increases BDNF levels in the normal brain and spinal cord. We attempted to determine whether swimming exercise improve motor function following experimental contusive spinal cord injury and whether motor outcome is associated with BDNF expression. Methods: Thirty six Sprague-Dawley rats (weight, 250 to 300 g) were divided into control (n=18) and experimental swimming group (n=18). Spinal cord injury was produced using NYU-spinal impactor at the eleven thoracic levels in both groups. Swimming exercise started $7^{th}$ day from SCI operation, lasted 5 min per day, 5 days a week for 4 weeks and then exercise times a day were increased in one number to each week. Motor functional recovery was determined by the Basso-Beattie-Bresnahan (BBB) locomotor rating scale, modified inclined board plane test, histological findings, H&E and BDNF expression observed at $1^{th}$, $3^{rd}$, $7^{th}$, $14^{th}$, $21^{st}$ and $28^{th}$day after injury. Results: 1. The BBB scores were higher in experimental group than control group at $14^{th}$, $21^{st}$ day (left hind limb) and at $21^{th}$ day (right hind limb) (p<0.05) after injury. 2. The inclined board plane test were significantly greater in experimental group than control group at $7^{th}$ day (p<0.05), $14^{th}$ and $28^{th}$ day (p<0.01) after injury. 3. The BDNF expression was severe revealed in experimental group than control group at $7^{th}$, $14^{th}$ and $28^{th}$ day after injury. Conclusion: This study suggests that swimming applied from the early phase after spinal cord injury be beneficial effects in motor functional recovery.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.391-399
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• 2009

The purposes of the present investigation was to evaluate the effects of loaded and unloaded swimming stimulation after central nerve system injury in the rats. SCI model rats were damaged in L1-L2 injected with 6-OHDA. The twenty one Sprague-Dawley adult male rats weights($200\pm10g$) were randomly divided into control group and 2 swimming groups and then swimming groups divided into 15 minute unloaded swimming group and 15 minute loaded swimming group by swimming intensity. Behavioral Change was evaluated by the BBB(Basso, Brestti, Brenahan) scales test and the maximal angles of the inclined board on which the rat could maintain its intial position for the progressive locomotor recovery. Using enzyme-linked immunosolbent assays(ELISA), we measured concentrations of brain-delived growth factor(BDNF) in serum after swimming. There was significant change of BBB scores in control group as compared to unloaded swimming group and loaded swimming group(p<.05), and unloaded swimming group were significantly higher than loaded swimming group(p<.05). The maximal angles of the inclined plane test were higher in the unloaded swimming group and loaded swimming group than the control group(p<.05), and loaded swimming group were significantly lower than unloaded swimming group(p<.05). There were singnificant difference of concentration of BDNF in serum change in each group(p<.05). The results suggest that swimming applied from the early phase after spinal cord injury may be beneficial in the early recovery of motor function.

• Korean Journal of Materials Research
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• v.15 no.8
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• pp.528-535
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• 2005

It is inclined to increase that use of hazardous substances such as lead(Pb), mercury (Hg), cadmium(Cd) etc. are prohibited in the electronics according to environmental friendly policies of an advanced nation for protecting environment of earth. As this reasons, many researches for ensuring the reliability were proceeding in Pb free soldering process. n the flux remains on the PCB(printed circuit board) in the soldering process or the electronics exposed to corrosive environment, it becomes the reasons of breakdown or malfunction of the electronics caused by corrosion. Therefore in this studies we researched the polarization and Tafel properties of Sn40Pb and SnCu system solders based on the electrochemical theory. The experimental polarization curves were measured in distilled ionized water and 1 mole $3.5 wt\%$ NaCl electrolyte of $40^{\circ}C$, pH 7.5. Ag/AgCl and graphite were utilized by reference and counter electrodes, respectively. To observe the electrochemical reaction, polarization test was conducted from -250mV to +250mV. From the polarization curves composed of anodic and cathodic curves, we obtained Tafel slop, reversible electrode potential(Ecorr) and exchange current density((cow). In these results, we compared the corrosion rate of SnPb and SnCu solders.