• 한국지반공학회논문집
• /
• 제19권6호
• /
• pp.285-298
• /
• 2003

본 연구에서는 경사판 시험기를 이용하여 매립지에 흔히 나타나는 토목섬유/토목섬유, 토목섬유/모래의 접촉 마찰특성을 평가하였다. 경사판 시험기는 연직응력이 낮은 상태에서의 전단 거동을 정확히 모사하는 시험기로 널리 알려져 있으며, 본 연구에서는 이 시험기를 이용하여 각 접촉면의 마찰각을 평가하는 동시에, 각 토목섬유에 유발되는 인장력도 측정하였다. 실험 결과, 연직응력의 크기, 토목섬유의 종류, 토목섬유의 흙의 구성에 따라 접촉면의 마찰각과 토목섬유에 유발되는 인장력이 각각 다르게 측정됨을 확인하였다. 한편, 본 연구에서는 모래/지오텍스타일/지오멤브레인, 즉 두개의 접촉면을 동시에 모사하는 실험을 실시하여, 지오멤브레인 상부에 위치하는 지오텍스타일로 인해 지오멤브레인에 유발되는 인장력이 감소함을 관찰하였다. 본 연구 결과는 동일한 접촉면을 대상으로 실시된 직접전단 시험 결과와 비교하였으며, 마지막으로 상자의 변위가 발생하기 시작하는 시점, 즉 각 접촉면의 한계 경사에서 토목섬유에 유발되는 인장력을 기존에 제안된 해석해와 비교하여, 해석해의 정확도와 설계시 적용 가능성에 대하여 고찰하였다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2004년도 춘계학술발표회
• /
• pp.356-363
• /
• 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.

• 대한토목학회논문집
• /
• 제26권2C호
• /
• pp.73-80
• /
• 2006

4종류 토목섬유 조합으로 구성된 4가지 토목섬유 접촉면의 정적 및 동적 하중 상태에서의 전단거동을 평가하였다. 정적하중 조건에서 경사판 시험과 직접전단 시험을 수행하였으며, 두가지 시험 결과를 상호 비교하였다. 비교 결과 직접전단 시험의 경우, 직접전단 시험이 수행되지 아니한 낮은 응력 단계에서의 접촉면 전단강도를 실제보다 크게 예측할 가능성이 높은 것으로 나타났다. 또한 정적상태에서 수행된 두 종류 시험을 통해 산정된 전단강도를 이용하여 곡선형태의 파괴 포락선식을 구할 수 있었다. 한편 정적 전단강도와 진동대시험을 통해 동적 하중 상태에서 구한 접촉면 전단강도를 비교하여, 하중 특성과 가해진 응력 크기에 따라 각기 다른 마찰 특성을 보임을 확인하였다. 따라서 토목섬유 사이의 접촉면 전단강도를 정확히 평가하기 위해서는 실제 현장에 설치되는 재료를 대상으로 예상되는 응력의 크기와 하중 유형을 고려하여 시험이 수행되어야 할 것이다.

• The Journal of Korean Physical Therapy
• /
• 제22권2호
• /
• pp.47-53
• /
• 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
• /
• 제19권3호
• /
• pp.1-9
• /
• 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.

• 한국콘텐츠학회논문지
• /
• 제9권12호
• /
• pp.391-399
• /
• 2009

본 연구의 목적은 중추신경계 손상의 쥐에 운동강도에 따른 신경계 회복을 알아보기 위해 부하수영과 무부하수영이 혈청 BDNF 농도와 행동학적 변화에 어떠한 영향을 미치는가를 확인하고자 하였다. 실험동물로는 Sprague-Dawley 수컷 흰쥐를 사용하였으며, Ketamine을 복강 내에 주사하여 마취한 뒤 제 1-2요추의 척수에 6-OHDA를 $100{\mu}{\ell}$ 주입하여 척수손상을 유발시켰다. 척수 손상으로 유발된 행동학적 변화를 알아보기 위해 BBB와 경사판 검사를 기록하였다. 혈청 BDNF는 수술 후 14일에 혈액을 채취해 흡광도를 측정하였다. 척수 손상 후 무부하군에서는 행동변화가 대조군에 비해 유의하게 증가하였고, 혈청 BDNF 농도는 다른 군에 비해 무부하군에서 증가하였다. 이러한 결과로 보아 저강도 수영운동을 중추신경 손상 후 초기에 적용하면 신경조직의 회복에 영향을 주리라 생각된다.

• 한국재료학회지
• /
• 제15권8호
• /
• pp.528-535
• /
• 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.