• Kyungpook Mathematical Journal
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• 제47권3호
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• pp.335-340
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• 2007

Let M be a hyperbolic 3-manifold such that ${\partial}M$ has at least two boundary tori ${\partial}_oM$ and ${\partial}_1M$. Suppose that M contains an essential orientable surface P of genus $g$ with one outer boundary component ${\partial}_oP$, lying in ${\partial}_oM$ and having slope ${\lambda}$ in ${\partial}_oM$, and $p$ inner boundary components ${\partial}_iP$, $i=1$, ${\cdots}$, $p$, each having slope ${\alpha}$ in ${\partial}_1M$. Let ${\beta}$ be a slope in ${\partial}_1M$ and suppose that $M({\beta})$ is toroidal. Let $\hat{T}$ be a minimal essential torus in $M({\beta})$, which means that $\hat{T}$ is pierced a minimal number of times by the core of the ${\beta}$-Dehn filling, among all essential tori in $M({\beta})$. Let $T=\hat{T}{\cap}M$ and denote by $t$ the number of components of ${\partial}T$. In this paper we prove: (i) if $t{\geq}3$, then ${\Delta}({\alpha},{\beta}){\leq}6+\frac{10g-5}{p}$, (ii) If $t=2$, then ${\Delta}({\alpha},{\beta}){\leq}13+\frac{24g-12}{p}$, (iii) If $t=1$, then ${\Delta}({\alpha},{\beta}){\leq}1$.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.129-136
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• 2005

The deterministic analysis method has generally used to evaluate the slope stability and it evaluates the slope stability with decision value that is a representative value of design variables. However, one of disadvantages in the deterministic approach is there is not able to consider the uncertainty of soil strength properties, even though it is the biggest influential parameter of the slope stability. On the other hand, the limit state design(LSD) can take a consideration of uncertainties and computes both the reliability index and the probability of failure. LSD method is capable of overcoming the disadvantages of deterministic method and evaluating the slope stability more reliably. In this study, both the mean value and standard deviation of the internal land's representative soil strength properties applied to process the LSD method. The major purpose of this study is to gauge the general applicability of the limit state design in soil slope and to weigh the comparative validity of the proposed partial safety factor. In order to reach the aim of this study, the partial safety factor and resistance factor which totally satisfied the slope's overall safety factor were calculated by the load and resistance safety factor design (LRFD).

• Geomechanics and Engineering
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• 제6권2호
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• pp.99-115
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• 2014

Uncertainties in design variables and design equations have a significant impact on the safety of geotechnical structures like retaining walls and slopes. This paper presents a possible framework for obtaining the partial safety factors based on reliability approach for different random variables affecting the stability of a reinforced concrete cantilever retaining wall and a slope under static loading conditions. Reliability analysis is carried out by Mean First Order Second Moment Method, Point Estimate Method, Monte Carlo Simulation and Response Surface Methodology. A target reliability index ${\beta}$ = 3 is set and partial safety factors for each random variable are calculated based on different coefficient of variations of the random variables. The study shows that although deterministic analysis reveals a safety factor greater than 1.5 which is considered to be safe in conventional approach, reliability analysis indicates quite high failure probability due to variation of soil properties. The results also reveal that a higher factor of safety is required for internal friction angle ${\varphi}$, while almost negligible values of safety factors are required for soil unit weight ${\gamma}$ in case of cantilever retaining wall and soil unit weight ${\gamma}$ and cohesion c in case of slope. Importance of partial safety factors is shown by analyzing two simple geotechnical structures. However, it can be applied for any complex system to achieve economization.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.162-163
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• 2006

XLPE is used to insulator for Ultra High Voltage power cable. It is easy to processing also has a good insulating property. The study for diagnosis of lifetime and improvement is proceeding continuously. In this paper, it is investigated partial discharge distribution according to slope of needle electrode 0, 20, $40^{\circ}$. Applied voltage is 0.5 [kV/s] by step form for inception voltage. As the result of study, we conformed that increase of slope led to reduce of discharge number and total discharge quantity.

• Journal of Forest and Environmental Science
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• 제14권1호
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• pp.145-156
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• 1998

본 연구는 집중호우로 인하여 임도사면 붕괴가 발생한 강원도 춘천시 지역의 5개 임도(백양임도, 변가터임도, 사오랑임도, 부귀임도, 당림임도)를 대상으로 수량화이론(II)에 의한 절토사면의 붕괴위험 예측에 관하여 분석하였다. 그 결과는 다음과 같다. 임도 절토사면 붕괴는 주로 절토부 구조적인 요인과 식생, 지형적인 요인이 복합적으로 작용하여 발생하는 것으로 나타났다. 또한 편상관계수(partial correlation coefficient) 및 범위(range) 값에 의한 절토사면의 붕괴예측 결과는 절토길이 8m이상, 토심이 2.5m이상, 산지경사 $30^{\circ}{\sim}50^{\circ}$사이, 절토피복율이 무식생인 경우, 절토경사 $60^{\circ}$ 이상에서 붕괴위험도가 높게 나타났으며, 판별적중율은 90.1%이었다.

• 대한조선학회논문집
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• 제44권6호
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• pp.666-674
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• 2007

It is very important to estimate static squeezing pressure distributions for lining material of sterntube after bearing at dry dock stage since the maximum squeezing pressure value can be one of the significant characteristics representing coming navigation performances of the propulsion system. Moderate oil film pressure between lining material and propulsion shaft is also essential for safe ship service. In this paper, Hertz contact theory is explained to derive static squeezing pressure. Reynolds equation simplified from Navier-Stokes equation is centrally differentiated to numerically obtain dynamic oil film pressures. New shaft alignment technology of nonlinear elastic multi-support bearing elements is also used in order to obtain external forces acting on lining material of bearing. For 300K DWT class VLCC with synthetic bush of sterntube after bearing, static squeezing pressures are calculated using derived external forces and Hertz contact theory. Optimum partial slope of the after bush is presented by parametric shaft alignment analyses. Dynamic oil film pressures are comparatively evaluated for partially bored and unbored after bush. Finally it is proved that the partial slope can drastically reduce oil film pressure during engine running.

• 한국의류학회지
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• 제23권6호
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• pp.864-875
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• 1999

This study was done to classify type os arms and to correspond these types with partial somatotype of upper body such as lateral views of upper body shapes of shoulder. The subjects of this study were female college students of twenties 58 anthropometric and photographic data were measured. The results were as follows : 1. Form the factor analysis arm girth/armscye size factor arm length factor the slope of lower arm, arm factor the curves of armscye the roundness of arm/shapes of shoulder the slope of upper arm factor were obtained. 2. By using factor scores 4 clusters of arm types were extracted. The characteristics of these clusters were projections of armscy slant of lower arm thick-set canelike. 3. Four types of arm were corresponded with the specified lateral views of upper body directions of shoulder slopes of shoulder.

• 한국해안·해양공학회논문집
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• 제21권4호
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• pp.316-325
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• 2009

국제적인 항만시설물 사면안정해석 설계기준을 분석하고 그 결과를 비교하였다. 사면안정해석에 사용된 설계기준은 한계상태 설계법에 근거한 중국, 유럽 및 일본의 설계방법이다. 사면안정해석시 공통적으로 파괴활동면은 원호 활동면 가정을 기본으로 하고 있다. 해석방법에 있어서 중국은 수정 Fellenius법에 근간하고 있으나 근래에 간편 Bishop법으로 변화하고 있다. 유럽은 Morgenstern & Price법 또는 Bishop법을 추천하고 있다. 반면, 일본은 수정 Fellenius법을 우선시하고 간편 Bishop법은 두꺼운 사질토 지반 등에 선택적으로 이용하도록 하고 있다. 특별하게도 유럽은 포괄적 부분계수 및 재료계수를 규정하는 반면, 일본은 각 구조물별로 경험적 재료계수를 명시하고 있다. 중국에서는 포괄적 부분계수의 최소범위를 규정하고, 안정조건에 따라 특정한 시험에 의한 강도지수를 사용하도록 구체적으로 명시하고 있다. 설계사례를 통한 사면안전율을 비교한 결과, 중국, 일본 및유럽 순으로 높게 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.179-184
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• 2005

Shear strength parameters obtained from filed survey are important factors in the analysis of slope stability. In this study, sensitivity analysis was performed to evaluate the effect of input parameters on the analysis of slope stability. The input parameters selected for sensitivity analysis were slope angle, cohesion, and friction angle. Monte-Carlo Simulation method was used for calculating input parameters and the factor of safety was computed by means of limit equilibrium method. A rock slope, which has failed in the field, was used for the sensitivity analysis in the analysis of slope stability. The result of analysis shows that the factor of safety of the rock slope was a little low. From partial correlation coefficient(PPC) of input parameters determined from the sensitivity analysis, slope stability was dependant on cohesion and slope angle. The effect of friction angle was lower than that of cohesion and slope angle on slope stability.

• 지질공학
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• 제15권1호
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• pp.9-17
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• 2005

본 연구는 전라남도 장성군 일대의 석회암지대에서 강우로 인해 파괴된 절개사면을 대상으로 시료를 채취하여 물리적ㆍ역학적 특성을 파악하고 강우로 인한 사면 안정 해석을 통해 사면구배의 변화에 따른 안전율의 변화를 규명하였다. 연구지역 석회암 풍화토는 석영, 정장석, 깁사이트, 침철석 등으로 구성되어 있고 비중은 2.73, 통일분류상 SC에 해당되며 모암에서 풍화가 진행되면서 칼슘성분이 현저하게 감소하였다. 투수계 수는 2.56×10/sup -4/ cm/ sec 로서 실트 성 점토의 투수계수와 비슷한 값을 보였고 전단시험결과 불포화토에서 포화토로 변할수록 점착력은 3.0 t/㎡에서 0.72 t/㎡로 현저하게 줄어들며 내부마찰각 Φ 값도 감소하는 경향을 보였다. 강우로 인한 사면안정 해석시 강우강도를 고려한 침투심도를 구하는 것이 합리적이며 사면안정해석결과 침투심도가 클수록 사면의 안전율은 낮아져서 불안정하게 되고 침윤선을 고려한 절토사면의 최소안전율 1.5와 비교 시 강우를 고려한 석회암 풍화토의 절토사면 구배는 1 ： 1.2이상 되어야 안전율을 만족하는 것으로 나타났다. 또한, 불포화토에서 포화토로 변할수록 점착력의 감소는 사면의 안전율감소에 많은 영향을 미침을 알 수 있었다.