• Proceedings of the Korean Fiber Society Conference
• /
• 1994.10a
• /
• pp.50-50
• /
• 1994

• Journal of Environmental Impact Assessment
• /
• v.25 no.6
• /
• pp.369-383
• /
• 2016

A distributed watershed model CAMEL(Chemicals, Agricultural Management and Erosion Losses) was applied to a part of grazing grassland and vegetation buffer strip(VBS) located in Daegwanryeong, Korea. A set of scenario analyses was carried out for grassland and VBS with various combinations of VBS widths, soil textures and ground surface slopes. The simulation results indicate that annual direct runoff decreases with wider VBS and the removal efficiency of pollutants generally decrease with steeper slopes. The removal efficiency of sediment is not significantly different with VBS widths. For gentle and medium slopes($10^{\circ}$, $20^{\circ}$), the removal efficiency of TOC and TN is not significantly different with VBS widths. As for a steep slope($30^{\circ}$), however, the removal efficiency of TOC and TN increases with narrower VBS. The removal efficiency of TP is generally high except for medium and steep slope of sandy loam where the removal efficiency of TP increases with wider VBS. This result of TP is contrary to the results of TOC and TN due to the adsorption characteristics of phosphorus associated with fine sediment particles. It is expected that CAMEL can be used for evaluating the effectiveness of VBS to reduce non-point source pollution discharges.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.5C
• /
• pp.231-238
• /
• 2012

The rockbolt functions as a main support, which restricts enlargement of the plasticity area and increases stability in the original ground around tunnels, and prevents a second deformation of an excavated surface by supplementing vulnerability arising from opening of the excavated surface. System bolting is generally applied if ground conditions are bad. System bolting is generally installed perpendicular to the excavation direction in every span. If a place is narrow, or it is difficult to insert bolts due to construction conditions, it may be connected and used with short bolts, or installed obliquely. In this study, laboratory model tests were performed to analyze the effect of the ground being reinforced by inclined bolts, based on a bending theory that assumes that the reinforced ground is a simple beam. In all test cases, deflections and vertical earth pressures induced by overburden soil pressure were measured. Total of 99 model tests were carried out, by changing the installation angle of bolts, lateral and longitudinal distance of bolts, and soil height. The model test results indicated that when the installation angle of bolts was less than $75^{\circ}$, deflections of model beams tended to increase rapidly. Also, the relaxed load that was calculated by earth pressure was rapidly increased when the installation angle of bolts was less than $75^{\circ}$. However, the optimum installation angle of inclined bolts was judged to be in the range of $90^{\circ}{\sim}75^{\circ}$. Also, as might be expected, the reinforcement effect of bolts was increased when the longitudinal and lateral distance of bolts was decreased.

• Fire Science and Engineering
• /
• v.20 no.4 s.64
• /
• pp.1-12
• /
• 2006

In this study, CFD computer simulations by FDS are carried out in order to confirm the performance of the combined operation of both sprinkler system and smoke curtain of 0.54 m depth installed for cooling and blocking the smoke which propagates beneath the sloped ceiling of a stairway corridor of which dimensions are 17.92 m long, 4.00 m wide, and 6.12 m high. It is shown that the response time of sprinklers decreases with fire size and it increases more about 1.1 second in case without smoke curtain than in case with smoke curtain, that the time of smoke transport from the fire source to the stairway outlet decreases considerably with fire size, and that the delay effect of smoke transport is not related to the sprinkler system, whether it is operated or not. This study shows that the combined operation of both sprinkler system and smoke curtain is very effective in smoke cooling, but it is a little for effect on smoke blockage. Although the hazard of skin burn due to radiative heat flux from hot smoke layer is decreased by spray cooling effect, the hazard of smoke suffocation and the weakening of visibility is increased by smoke downdrag and the turbulence of smoke-air mixing due to water spray. These conditions may result in preventing occupants from going out of the stairway during evacuation.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2008.05a
• /
• pp.1669-1674
• /
• 2008

여수로는 방류량 월류시 한계류 상태와 고유속의 사류상태가 복합적으로 일어나는 흐름형태를 가지고 있어 여수로의 방류능력에 대한 평가시 수치해석 및 수리모형 실험을 통해 검증하고 있다. 여수로의 방류능력은 여수로 월류부 전면부 바닥고, 월류부 상 하류 경사, 월류웨어고 뿐만 아니라 교대 및 교각의 형상에 의해 영향을 받는다. 또한 월류웨어부를 지나 사류의 흐름양상을 보이는 천이부의 형상 및 후면 교각의 연장에 따라서도 급경사수로부의 흐름이 급변하게 된다. 국내 대부분의 여수로는 전면부의 교각(Pier)형상이 구조적인 안정성을 이유로 직벽형 설계방법을 일반적으로 채택하고 있으며 국내 및 미개척국(USBR)의 설계기준 또한 여수로 교각과 교대부의 평면 형상만을 고려할 수 있도록 제시하고 있어 국내 대부분의 수리 구조물들이 획일적인 구조물 형상을 벗어나지 못하고 있는 실정이다. 본 연구에서는 수치 및 수리모형 실험을 통해 국내 대댐에 설계되어 있는 직벽형태와 본 연구에서 제시하고 있는 켄틸러버형의 교각형상에 따른 여수로의 수리적 흐름양상 및 방류능력을 비교하여 그 효과를 검토하였다. 검토결과 켄틸러버형태의 교각이 설치된 여수로의 경우 직벽형에 비하여 전면부 수위상승 및 흐름교란이 적게 발생하였으며, 방류능력 또한 개선되는 결과를 나타내었고, 후면 교각의 연장이 길고 점차 축소될수록 급경사수로부의 흐름이 안정적인 것으로 나타났다.

• Journal of the Korean earth science society
• /
• v.35 no.7
• /
• pp.529-536
• /
• 2014

In this paper, the automatic determination algorithm of strike and dip of a line source using gravity gradient on a single profile is proposed. In general, the gravity gradient tensor due to a line source has only two independent components because of its 2-Dimensional (2-D) characteristics. However, if the line source has the strike and dip regarding the observation profile, it comes to have five independent components. The proposed algorithm of the determination both strike and dip is based on the rotational transform that converts full gravity gradient tensor to reduced 2-D gravity gradient tensor. The least-square method is applied in order to find optimum rotational angles that make one of the row components minimalized simultaneously. The two synthetic cases of a line source are represented; one has strike only and the other has both strike and dip. This study finds that the automatic determination method using gravity gradient tensor can find directions of a line source in each case.

• Geotechnical Engineering
• /
• v.13 no.4
• /
• pp.55-66
• /
• 1997

In order to investigate the influence of installation angle of reticulated root piles(RRP) on their lateral load capacities, model tests of lateral loads on RRP with various installation angles $0^{\circ}\;, 5^{\circ}\;, 10^{\circ}\;, 15^{\circ}\;, 20^{\circ}\;,and 25^{\circ}$ are carried out. One set of RRP consists of 12 piles which are installed in circular patterns forming two concentric circles, each of which has 6 piles. Each pile made of a steel bar of 5mm in diameter and 350mm in length, is coated with sand until the bar has the diameter of 6.5mm. According to the test results, RRP's response is travily influenced by the displacement level. At low displacement level(1m), lateral load capacity increases as the installation angle is increased. However, the value of the optimum installation angle decreases as the displacement level is increased. In fact, it is found to be $17.5^{\circ}$ at 6mm lateral displacement. The ratios of the lateral resistances for the optimum installation angles to those for the vertical RRP decrease as the lateral displacements are increased. Thus the effect of slant ins angle of RRP is expected to be reduced at higher level of lateral displacement.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
• /
• 2010.06a
• /
• pp.128-129
• /
• 2010

기존의 고도계는 레이더 특성에 의해 직하부의 높이 값을 정밀하게 관측할 수 없었다. 그러나 레이더 간섭 고도계는 SAR(Synthetic Aperture Radar) 영상의 칩 펄스(Chirp Pulse)를 이용한 고정밀 경사거리(Slant Range Distance)관측, 도플러 효과를 이용한 고정밀 경사각(Squint Angle)의 관측 및 레이더 간섭기법(SAR Interferometry)을 이용한 고정밀 관측각(Look Angle)의 관측을 가능하게 하였다. 이 연구의 목적은 레이더 간섭 고도계의 효율적인 신호처리 기법의 개발에 있다.

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2009.11a
• /
• pp.127-128
• /
• 2009

30데니어 이하 세데니어의 특수한 광택감을 활용하여 그 효과를 제어하는 기술, 경사의 경우 원사의 사종과 굵기를 조절해서 경사 사이로 비치는 위사의 광택을 제어할 수 있는 방법에 대해 원사의 선정, 사가공, 사염, 제직, 전처리, 염색, 후가공 공정 전반에 걸쳐 기기 및 조건을 변경하여 시제품을 제작중이다.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.6
• /
• pp.397-406
• /
• 2003

Several sensor systems are used to estimate the reinforcing effect of stabilizing pile in slopes, and to find a failure surface in slopes effectively. FBG(Fiber Brags Crating) sensor, V/W(Vibrating Wire) sensor and inclinometer have shown a great potentiality to serve real time health monitoring of the reinforcing structures. Field tests and test results have shown great solutions for sensor systems of Smart Structures. The purpose of this research is to seek for the relationships among the slope movement and the reinforcing effect of stabilizing pile, and the strain distribution of stabilizing pile in a active zone by analyzing the data from the in-situ measurement so that the possible failure surface should be well defined based on the relationships. The field test results have shown that the data by FBG sensor are well coincided with those of V/W sensor and inclinometer, and the reinforcing effect of the stabilizing pile is good enough.