• 터널과지하공간
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• 제11권4호
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• pp.328-338
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• 2001

Fiber Glass Tube(FGT) 또는 steel pipe를 이용한 터널막장의 수평보강공법 그리고 강관다단공법 등은 터널 굴착시 터널막장의 안정성이 확보되지 못할 경우에 흔히 사용된다. 그러나 이러한 공법이 사용된 터널의 역학적 거동은 아직 충분히 알려진 바가 없으며, 따라서 설계와 전산해석 과정에서 경험에 의존하는 경우가 많고 공법의 합리적인 적용이 어려운 실정이다. 본 연구에서는 복합체 역학을 이용한 보강공법의 전산해석 단순화 방법의 적용성을 검증하였고, 강화지반의 등가탄성계수는 평균장 이론과 변형률 에너지 이론을 사용하여 도출하였다. 다양한 보강패턴에 따른 터널막장의 거동에 관한 매개변수 연구를 수행하였다.

• 한국터널지하공간학회 논문집
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• 제6권3호
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• pp.259-267
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• 2004

The practice of introducing and grouting reinforced fiber glass pipes or bar into the core to be excavated to maintain stable the tunnel face during excavation has been applied to many tunnels, where difficult geotechnical conditions are present, with good results in terms of safety and speed of works. This reinforcing technique, initially developed to be used jointly with the mechanical precut in clay, has been widely used with other geotechnical conditions as the only type of reinforcement or joined with other ground consolidation and/or reinforcement techniques (i.e. steel pipes or jet-grouting umbrella). At present same numerical researches have been carried out to find which are the real working conditions of the reinforcing elements but no final results have been obtained for the definition of the best design approaches. In this work the results of a three dimensional parametric numerical model is presented.

• 한국산학기술학회논문지
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• 제6권4호
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• pp.291-295
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• 2005

본 논문은 변형된 2-D PCA를 이용한 얼굴 인식 방법에 대하여 제안한다. 기존의 PCA는 1 차원 벡터들로 공분산 행렬을 구하는 반면에 2-D PCA는 2 차원 영상을 직접적으로 이용하여 공분산 행렬을 구한 후 그것의 고유값에 따른 고유벡터를 구하여 특징 벡터들을 추출한다. 제안 방법은 두 개의 공분산 행렬들을 이용하여 선형 변환 행렬을 구하는 변형된 2-D PCA 방법을 적용하여 얼굴을 인식한다. 실험 결과는 2-D PCA 보다 제안된 방법이 $1\%$ 정도 얼굴 인식률이 더 좋으며, 안정된 인식률을 보여준다.

• 한국안전학회지
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• 제21권2호
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• pp.107-113
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• 2006

Earthquake motion is one of the most significant influence factors on the slope stability. In this paper, an effective stress analysis with the elasto-plastic model was carried out to investigate the behavior of the slope stability subjected to the successive two strong earthquake motions, fore and main shock. The major influence of fore shock to the slope stability was considered as the existence of the residual excess pore water pressure. The paper presents the influence of the existence of the fore shock to slope stability using the numerical analyses. In conclusion, the excess pore pressure by the fore shock was not dissipated during the 7hrs of consolidation. By this residual excess pore water pressure, the factor of safety at the sliding face showed the minimum values, and the deformations of slope was large when compared with the case that considered the main shock only. Furthermore, the minimum of the factor of safety came out after the end of the earthquake motion.

• The Journal of Asian Finance, Economics and Business
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• 제8권4호
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• pp.151-159
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• 2021

This study aims to compare the level of stability of the Islamic banking system in the ASEAN region, particularly in Indonesia, Malaysia and Brunei Darussalam in the face of macroeconomic turmoil. The data used in this study is secondary data obtained from the official website of the government and banks of each country, with sampling using purposive sampling technique during the period 2013 to 2019. The data analysis method used is panel data using Eviews software. The results showed that the average Z-score value of Islamic banking during the study period in each country was Indonesia (15.61), Malaysia (15.56) and Brunei Darussalam (19.10). The GDP (X1) has a positive effect on the stability of Islamic banking by 54.29%, inflation (X2) has a negative effect of -12.24% on the stability of Islamic banking, and the exchange rate (X3) has a positive effect on the stability of Islamic banking by 42.58%. The findings of this study indicate that the three countries have an average Z-score value that is higher than 2.99, so this shows that Islamic banking in several ASEAN countries is in a stable condition. In addition, a higher GDP and a stronger exchange rate can also encourage a more stable Islamic banking.

• Steel and Composite Structures
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• 제23권5호
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• pp.529-541
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• 2017

In the present study, vibration analysis of functionally graded carbon nanotube reinforced composite (FGCNTRC) plate moving in two directions is investigated. Various types of shear deformation theories are utilized to obtain more accurate and simplest theory. Single-walled carbon nanotubes (SWCNTs) are selected as a reinforcement of composite face sheets inside Poly methyl methacrylate (PMMA) matrix. Moreover, different kinds of distributions of CNTs are considered. Based on extended rule of mixture, the structural properties of composite face sheets are considered. Motion equations are obtained by Hamilton's principle and solved analytically. Influences of various parameters such as moving speed in x and y directions, volume fraction and distribution of CNTs, orthotropic viscoelastic surrounding medium, thickness and aspect ratio of composite plate on the vibration characteristics of moving system are discussed in details. The results indicated that thenatural frequency or stability of FGCNTRC plate is strongly dependent on axially moving speed. Moreover, a better configuration of the nanotube embedded in plate can be used to increase the critical speed, as a result, the stability is improved. The results of this investigation can be used in design and manufacturing of marine vessels and aircrafts.

• 한국지반공학회논문집
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• 제16권1호
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• pp.191-201
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• 2000

본 연구에서는 굴착부지가 넓고 지하수위가 높은 점성토지반에 얕은 굴착시 종래에 널리 적용되었던 강널말뚝 흙막이공 대신 줄말뚝을 이용한 흙막이공을 제안하였다. 줄말뚝을 이용한 흙막이 구조물의 거동을 관찰하기 위하여 지하굴착기간 동안 경사계 및 지하수위계를 설치하여 말뚝과 지반의 수평변위와 지하수위 변화를 조사하였다. 현장계측결과 말뚝과 지반의 변형거동은 굴착면 기울기, 말뚝두부구속조건, 말뚝설치간격, 굴착지반의 안정수 등의 요소에 영향을 받는 것으로 나타났다. 그리고 줄말뚝을 이용한 흙막이공의 시공성과 안정성뿐만 아니라 근접시공의 문제점이 없는 연약지반에서는 강널말뚝 흙막이공보다 경제적인 공법임을 확인하였다.

• 한국지반공학회지:지반
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• 제12권1호
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• pp.47-62
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• 1996

The bedding zone which influence directly to the safety of dam is supporting the face slab under hydraulic load in concrete faced rockfill dam. In case that leakage is developed due to various ruptured joint or cracks of face slab and etc., the bedding zone should limit the leakage by low permeability and keep the internal stability. In this study for the proper coefficient of permeability various properties, such as gradation, dry density, performance of embankment work and etc. were analysed. The results from the large scale test of permeability and density are summerized as follows : 1. Coefficient of permeability is decreased clearly by increase of dry density. 2. The particles smaller than the No.4 strive( p,) greatly influences the permeability under dry density of 2.24t 1 m3. 3. In case of C.40 and p,40%, even if dry density decreased to 2.0t/m3, the permeability coefficient is assumed to u x1-scm/s and internal stability is abtained. 4. Generally in dam construction since dry density and uniformity coefficient of bedding zone were higher than 2.2t/m3 and 50 respectively p, of 30~40% is assumed to be suitable and permeability coefficient of below 1$\times$10-3cm l s is expectable.

• 한국전산유체공학회지
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• 제7권1호
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• pp.10-19
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• 2002

The non-staggered(collocated) grid approach in which all the solution variables are located at the centers of control volumes is very popular for incompressible flow analyses because of its numerical efficiency on the curvilinear or unstructured grids. Rhie and Chow's paper is the first in using non-staggered grid method for SIMPLE algorithm, where pressure weighted interpolation was used to prevent decoupling of pressure and velocity. But it has been known that this non-staggered grid method has stability problems when pressure fields are nonlinear like in natural convection flows. Also Rhie-Chow scheme generates large numerical diffusion near curved walls. The cause of these unwanted problems is too large pressure damping term compared to the magnitude of face velocity. In this study the magnitude of pressure damping term of Rhie-Chow's method is limited to 1∼10% of face velocity to prevent physically unreasonable solutions. The wall pressure extrapolation which is necessary for cell-centered FVM is another source of numerical errors. Some methods are applied in a unstructured FV solver and analyzed in view of numerical accuracy. Here, two natural convection problems are solved to check the effect of the Rhie-Chow's method on numerical stability. And numerical diffusion from Rhie-Chow's method is studied by solving the inviscid flow around a circular cylinder.

• 한국지반환경공학회 논문집
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• 제6권2호
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• pp.15-20
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• 2005

도로 주변 절토사면 상부에 시공되는 산마루 측구는 상부로부터 흘러내리는 지표수를 원활히 배수시켜 절개면으로 유입되는 것을 방지한다. 국내의 경우 전 국토의 70%이상이 산악지로 구성되어 있어 도로 개설에 따른 절개면의 발생은 필연적이다. 여름 집중호우와 간극수압의 증가로 인하여 절개면의 불안정성은 증가된다. 그러나 절토사면 상부에 시공되어 있는 산마루측구는 품질관리의 어려움과 배수능력 부족 등의 문제점들이 있다. 따라서, 본 논문에서는 산마루 측구의 깊이와 투수계수에 따른 절토사면의 안전율 변화를 분석하였으며 적절한 측구 설치깊이를 결정하였다.