• Journal of the Korean Data and Information Science Society
• /
• 제22권4호
• /
• pp.691-699
• /
• 2011

현재까지 우리나라뿐만 아니라 세계적으로 급경사지 붕괴는 대표적인 자연재해로 알려져 있다. 급경사지 붕괴 피해를 방지하기 위해 행해진 많은 선행 연구를 바탕으로 일부 국내기관에서는 급경사지 평가표를 만들어 붕괴 예측에 활용하고 있다. 하지만, 대부분의 기존 연구는 비통계전문가들에 의해 행해졌기 때문에 평가표 구성의 통계적 타당성을 제시하지 못했다. 본 연구는 전국 지역을 대상으로 급경사지 (암반사면, 토사사면) 붕괴에 영향을 미칠 것으로 예상되는 인자들의 자료를 수집하고 그 인자들의 가중치를 판정하기 위하여 로지스틱 회귀분석 방법을 사용하였다. 선행연구들 중에 로지스틱 회귀분석을 이용한 기존의 연구들이 있었지만 다중공선성을 전혀 고려하지 않았기 때문에 결과가 신뢰할 만하지 못하다. 본 연구에서는 다중공선성을 제거된 급경사지 붕괴 예측모형을 제시하였다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.771-774
• /
• 1996

This paper presents a continuous time varying sliding surface that allows faster tracking and really guarantees robust contro land smooths control inputs. And this method is evaluated by applying to robot manipulator.

• 한국유체기계학회 논문집
• /
• 제9권5호
• /
• pp.7-13
• /
• 2006

In the present study, we develop an analysis module to be applicable to design of sliding thrust bearings. The pressure equation is solved by using the finite element method. Average lubricant temperature is obtained from using the energy balance method. The module developed has been applied to three types of thrust bearing, such as tapered-land thrust bearings of angular and diamond types, and tilting-pad thrust bearings. Effects of the dam of the tapered-lad thrust bearings have also been investigated. It has been seen that the tapered-land thrust bearings of angular type result in the highest load capacity, while the tilting pad thrust bearings result in the lowest lubricant temperature. It has also been seen that the dam in the tapered-land thrust bearings increases both the load capacity and lubricant temperature.

• Tribology and Lubricants
• /
• 제13권1호
• /
• pp.21-27
• /
• 1997

The friction and wear behavior of undulated surfaces made of tin base babbit are examined experimentally at the low sliding speed with severe loading condition. Steel is used as counterface disk material under pin-on-disk type sliding condition. Undulated surfaces can improve the friction and wear properties under dry friction condition since undulated surfaces trap wear particles in their cavities and prohibit wear particles from agglomerating. However, under boundary lubrication condition, friction and wear properties of undulated surfaces are inferior to those of flat surfaces. It is shown that land width and the ratio of wear volume to cavity volume are the most important factors in friction behavior of undulated surfaces under dry friction condition, and there exists optimum land width minimizing friction and wear of undulated surfaces.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
• /
• pp.875-883
• /
• 2008

The amount of granite distribution area occupies about 40 - 50% of Korean Peninsula. The granite irregularly Intruded through preCambrian to Tertiary times but in Jurassic time so called, Daebo granite most widely crops out in Korean Peninsula. In addition to Bulkuksa Grante which intruded at Cretaceous time crops out at the southern part of Korean Peninsula and in northern part Triassic Songrim Granite is distributed. These granites have equigranular texture and are relatively isotropic. Their uniaxial compressive strength is above $1,500kg/cm^2$ and also seismic velocity is over 2,000m/sec. When these rocks receive a weathering action, the feldspar weathers first and the quartz grains remain plentifully to make the "Masato(Korean name)". Also when the granite receives a weathering action, quite often it make sheeting joint which is topographically parallel to the earth surface and also make a (so called, onion structure. These weathering phenomena easily make a land sliding when it is heavy rain and weathering surface is irregular.

• 지질공학
• /
• 제31권3호
• /
• pp.269-281
• /
• 2021

Land creeping is the imperceptibly slow, steady, downward movement o f slope-forming soil or rock. Because creep-related failures occur frequently on a large scale without notice, they can be hazardous to both property and human life. Korea Forest Service has operated the prevention and response system from land creeping which has been on the rise since 2018. We categorized and proposed three survey steps (e.g., preliminary, regional, detailed) for investigation of creeping susceptibility site with a focus on geophysical mapping of a selected test site, Yongheung-dong, Pohang, Korea. The combination of geophysical (dipole-dipole electrical resistivity tomography and reciprocal seismic refraction technique, well-logging), geotechnical studies (standard penetrating test, laboratory tests), field mapping (tension cracks, uplift, fault), and comprehensive interpretation of their results provided the reliable information of the subsurface structures including the failure surface. To further investigate the subsurface structure including the sliding zone, we performed high-resolution geophysical mapping in addition to the regional survey. High-resolution seismic velocity structures are employed for stability analysis because they provided more simplified layers of weathering rock, soft rock, and hard rock. Curved slip plane of the land creeping is effectively delineated with a shape of downslope sliding and upward pushing at the apex of high resistive bedrock in high-resolution electrical resistivity model with clay-mineral contents taken into account. Proposed survey steps and comprehensive interpretation schemes of the results from geological, geophysical, and geotechnical data should be effective for data sets collected in a similar environment to land-creeping susceptibility area.

• 한국지반공학회논문집
• /
• 제38권5호
• /
• pp.19-33
• /
• 2022

지진시 성토사면의 잔류변위 예측에 가장 많이 사용되는 방법은 Newmark변위법이다. Newmark변위법은 지진시 강체원호의 관성력에 의한 미끌어짐량을 산정하는 방법으로 한계상태평형이론에 근거하여 산정된다. 따라서, 원호의 미끌어짐이 발생하지 않는 항복가속도 이하의 지진이 발생하는 경우 잔류변위가 발생하지 않는다고 가정한다. Newmark 변위법은 최초 제안 이후 지진응답해석기법의 결과를 도입하는 방향으로 개선되었다. 본 논문에서는 방조제 예제 단면에 대해서 Newmark변위법의 적용방법과 비선형응답이력 해석을 통한 내진성능평가 결과의 차이를 살펴보았다. 검토 결과, 설계안전율이 큰 방조제 제체에서는 Newmark변위법에 의한 잔류변위는 거의 발생하지 않았다. 반면, 비선형 응답이력해석의 결과는 비교적 유의미한 잔류변위를 나타냄을 알 수 있었다.

• 한국물환경학회지
• /
• 제26권4호
• /
• pp.691-699
• /
• 2010

In recent years, increases in impervious areas with rapid urbanization and land use changes are causing numerous hydrologic cycle and environmental problems. Impermeable pavement have a various defect such as collection rainwater, decreasing of sliding resistance, and etc. In this study, the hydrologic cycle effect of permeable pavement were analyzed by the experiment and the numerical simulation. The numerical model used was a modified SWMM especially for considering the hydrologic cycle effect of permeable pavement. The parameters of modified SWMM were revised by the experimental results. Also, the effects of runoff quantity reduction are reviewed when permeable pavement is applied to Incheon Cheongna watershed. The hydrologic cycle analysis of Incheon Cheongna watershed, continuous simulations of urban runoff were performed. The analysis results of permeable pavement setup effect on runoff are follows: the surface runoff after permeable pavement setup decreases to 74.35% of the precipitation whereas the surface runoff before permeable pavement setup amounts to 81.38% of the precipitation; the infiltration after permeable pavement setup increases to 15.13% of the precipitation whereas the infiltration before permeable pavement setup amounts to 8.32% of the precipitation.

• 농업과학연구
• /
• 제25권1호
• /
• pp.97-106
• /
• 1998

본 연구는 현재 산사태 대책수립에 많이 이용되고 있는 원호활동 해석방법의 문제점을 규명하기 위하여 실시되었으며, 여기서 얻어진 결과를 요약하면 다음과 같다. 1. 40개의 모델사면을 지층에 따라 활동면을 분석해 본 결과, 풍화토와 풍화암의 경계 부분이 다른 부분에 비하여 활동이 일어날 가능성이 높은 것으로 나타났다. 2. 우리나라에서 발생하는 산사태의 대부분이 깊이 2m를 전후로 하여 토층의 경계부근등 주로 불연속면을 따라 발생하기 때문에 절취사변에 대한 산사태의 안정해석을 할때, 무한사면해석을 우선 고려하는 것이 안전한 설계가 될 것으로 판단된다. 3. 사면경사가 일정한 상태에서 사면길이만을 변화 시켰을 경우, 원호활동사면인 경우는 토층이 얕고 사면길이가 짧을수록 안전하였으나 무한사면인 경우는 사면길이에 관계없이 최소안전율은 동일하였다. 4. 우리나라 산사태의 대부분을 차지하는 사면경사 $30^{\circ}$의 조건으로 원호활동해석과 무한활동해석으로 분석한 결과, 상호간의 최소안전율의 차이가 많으며 원호활동해석 방법은 무한활동해석에 비해 과다하게 안전측으로 나타났다.

• 소성∙가공
• /
• 제18권7호
• /
• pp.565-571
• /
• 2009

This paper is concerned with the analysis on the surface stress profiles of perfectly plastic material in backward extrusion process. Due to heavy surface expansion appeared usually in the backward extrusion process, the tribological conditions along the interface between the material and the punch land are very severe. In the present study, the analyses have focused to reveal the surface conditions at the contact boundary for various punch shapes in terms of surface expansion, contact pressure, and relative movement between punch and workpiece which consists of sliding velocity and distance, respectively. Punch geometries adopted in the analysis include concave, hemispherical, pointed and ICFG recommended shapes. Extensive simulation has been conducted by applying the rigid-plastic finite element method to the backward extrusion process under different punch geometries. The simulation results are summarized in terms of surface expansion, contact pressure, sliding velocity and sliding distance at different reduction in height, deformation patterns, and load-stroke relationship, respectively.