• Journal of Korean Medical classics
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• v.13 no.2 s.17
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• pp.58-67
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• 2000

통과대문왕팔괘차서도화문왕팔괘방위도적연구(通過對文王八卦次序圖和文王八卦方位圖的硏究). 득도요여하결론(得到了如下結論). 1. 최초명명위문왕팔괘차서도화문왕팔괘방위도적인시소옹(最初命名爲文王八卦次序圖和文王八卦方位圖的人是邵雍). 문왕팔괘차서도화문왕팔괘방위도수연몰유시문왕소화적확체적근거(文王八卦次序圖和文王八卦方位圖雖然沒有是文王所畵的確切的根據), 단시종추연복희이(但是從推演伏羲易), 동사상결합(同事相結合), 최종확립여금적역학체계적인시문왕(最終確立如今的易學體系的人是文王). 이차환부합현금적역리(而且還符合現今的易理), 인차구유일정설복력(因此具有一定說服力). 2. 재문왕팔괘차서도중삼남유일양이음구성(在文王八卦次序圖中三男由一陽二陰構成). 삼녀유일음이양구성(三女由一陰二陽構成). 저가이용음양호근적원리진행설명(這可以用陰陽互根的原理進行說明). 3. 복희팔괘방위도현시모종공간상(伏羲八卦方位圖顯示某種空間相). 이문왕팔괘방위도칙현시사시(而文王八卦方位圖則顯示四時). 팔절적변화화만물생장적류행주기등시간상적변화(八節的變化和萬物生長的流行周期等時間上的變化). 4. 문왕팔괘방위도동사시적오행상일치(文王八卦方位圖同四時的五行相一致). 시상생관계(是相生關係), 팔괘당중각유양개목김토(八卦當中各有兩개木金土). 시유우형흔왕성(是由于形흔旺盛), 수화각유일개시유우기흔왕성(水火各有一개是由于氣흔旺盛). 5. 문왕팔괘방위도재표면상간호상시오행상생적관계(文王八卦方位圖在表面上看好象是五行相生的關係). 단시(但是), 상호성대면적팔괘적오행도성상극관계(相互成對面的八卦的五行都成相剋關係). 화동측상임적감수(和東側相臨的坎水) 간토(艮土) 진목(震木) 손목도시성상극관계(孫木都是成相剋關係). 종차가이지도상극시발전만물적주체(從此可以知道相剋是發展萬物的主體). 6. 대우복희팔괘전화위문왕팔괘적원리(對于伏羲八卦轉化爲文王八卦的原理), 수유각종이론제출(雖有各種理論提出). 단시상무확체적설법(但是尙無確切的說法). 7. 복희팔괘주요체현천도화외상등(伏羲八卦主要體現天道和外象等), 문왕팔괘측체현인사화내정등(文王八卦側體現人事和內情等). 8. 복희팔괘위체(伏羲八卦爲體), 문왕팔괘위용(文王八卦爲用). 복희팔괘중(伏羲八卦中), 위변화적주체적천지즉건곤위우중축(爲變化的主體的天地卽乾坤位于中軸). 문왕팔괘중(文王八卦中), 위변화적대용적일월즉감리위우중축(位變化的大用的日月卽坎離位于中軸). 9. 복희팔괘도속우표현춘천적변화지상적제일괘도(伏羲八卦圖屬于表現春天的變化之象的第一掛圖), 생괘도화창조도(生掛圖和倉曹圖), 문왕팔괘도칙속우표현하천적변화지상적제이괘도(文王八卦圖則屬于表現夏天的變化之象的第二掛圖), 장괘도화발전도(長掛圖和發展圖). 10. 문왕팔괘도시류행이치기용적역지용(文王八卦圖是流行以致其用的易之用), 표현무질서화혼란(表現無秩序和混亂), 위화여괴리상호란무적난음난양지상(韋和與乖離相互亂舞的亂陰亂陽之象). 11. 문왕팔괘도화낙서적변화원리상일치(文王八卦圖和洛書的變化原理相一致), 가이장낙서적수직접대응도문왕팔괘도중(可以將洛書的數直接對應到文王八卦圖中). 우명낙서팔괘도(又名洛書八卦圖). 구수도혹일구역(九數圖或一九易). 12. 문왕팔괘도적상대응적수자지합도위십(文王八卦圖的相對應的數字之合都爲十). 저예시료성괘도십수도적출현(這豫示了成掛圖十數圖的出現).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.7
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• pp.441-448
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• 2016

The thrust force created by a propeller depends on the incoming flow velocity and the rotational velocity of the propeller. The performance of the propeller can be described by dimensionless variables, advanced ratio, thrust coefficient, and power coefficient. This study included the application of the immersed boundary lattice Boltzmann method (IBLBM) with the stereo lithography (STL) file of the rotating object for performance analysis. The immersed boundary method included the addition of the external force term to the LB equation defined by the velocity difference between the lattice points of the propeller and the grid points in the domain. The flow by rotating a 4-blade propeller was simulated with various Reynolds numbers (Re) (including 100, 500 and 1000), with advanced ratios in the range of 0.2~1.4 to verify the suggested method. The typical tendency of the thrust efficiency of the propeller was obtained from the simulation results of different advanced ratios. It was also necessary to keep the maximum mesh size ratio of the propeller surface to a grid size below 3. Additionally, a sufficient length of the downstream region in the domain was maintained to ensure the numerical stability of the higher Re and advanced ratio flow.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.3
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• pp.93-100
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• 2021

Since the IB (Immersed Boundary) method, which can perform coupling analysis with objects and fluids having an impermeable boundary of arbitrary shape on a fixed grid system, has been developed, the IB method in various CFD models is increasing. The representative IB methods are the directing-forcing method and the ghost cell method. The directing-forcing type method numerically satisfies the boundary condition from the fluid force calculated at the boundary surface of the structure, and the ghost-cell type method is a computational method that satisfies the boundary condition through interpolation by placing a virtual cell inside the obstacle. These IB methods have a disadvantage in that the computational algorithm is complex. In this study, the simplified immersed boundary (SIB) method enables the analysis of temporary structures on a fixed grid system and is easy to expand to three proposed dimensions. The SIB method proposed in this study is based on a one-field model for immiscible two-phase fluid that assumes that the density function of each phase moves with the center of local mass. In addition, the volume-weighted average method using the density function of the solid was applied to handle moving solid structures, and the CIP method was applied to the advection calculation to prevent numerical diffusion. To examine the analysis performance of the proposed SIB method, a numerical simulation was performed on an object falling to the free water surface. The numerical analysis result reproduced the object falling to the free water surface well.

• Journal of the Korean Geotechnical Society
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• v.35 no.11
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• pp.7-14
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• 2019

The compacted bentonite buffer is one of the major components of an engineered barrier system (EBS) for the disposal of high-level radioactive waste (HLW), and it is considered the best candidate for the buffer material. The buffer is located between disposal canisters and near-field rock mass, and it interrupts the release of radionuclide from disposal canisters and protect them from the penetration of groundwater. At initial disposal condition, degree of saturation of the compacted bentonite buffer decreases because of high thermal quantities released from the disposal canisters. However, the degree of saturation of the compacted bentonite buffer gradually increases caused by inflow of groundwater. The saturated and unsaturated behavior of the buffer is a very important input data since it can determine the safety performance of EBS. Therefore, this paper investigated water retention capacity (WRC) for the Korean compacted bentonite buffer. The WRC of the compacted bentonite buffer was derived by measuring volumetric water content and water suction when temperature variation was between 24℃~125℃ considering decrease of degree of saturation with respect to temperature increase. The WRC was also derived with the same volumetric water content under the room temperature condition, and it showed 1~15% larger water suction than high temperature condition.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.4
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• pp.21-31
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• 2001

When an oil-spilling accident occurs at sea, it is of the primary importance to predict the amount of oil leakage for the swift response and decision-making. The simplest method of oil-leakage estimation is based on the hydrostatic pressure balance between oil inside the tank and seawater outside of leakage hole, that is the so-called Torricelli equilibrium relation. However, there exists discrepancy between the reality and the Torricelli relation, since the latter is obtained from the quasi-steady treatment of Bernoulli equation ignoring viscous friction. A preliminary experiment has been performed to find out the oil-leaking speed and shape. Soy-bean oil inside the inner tank was ejected into water of the outer tank through four different leakage holes to record the amount of oil leakage. Furthermore, a CFD (Computational Fluid Dynamics) method was utilized to simulate the experimental situation. The Wavier-Stokes equations were solved for two-density flow of oil and water. VOF method was employed to capture the shape of their interface. It is found that the oil-leaking speed varies due to the frictional resistance of the leakage hole passage dependent on its aspect ratio. The Torricelli factor relating the speed predicted by using the hydrostatic balance and the real leakage speed is assessed. For the present experimental setup, Torricelli factors were in the range of 35%~55% depending on the aspect ratio of leakage holes. On the other hand, CFD results predicted that Torricelli factor could be 52% regardless of the aspect ratio of the leakage holes, when the frictional resistance of leakage hole passage was neglected.

• Journal of the Korean Geotechnical Society
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• v.30 no.3
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• pp.47-58
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• 2014

To investigate the unsaturated characteristics of the tailings obtained from the waste dump at Imgi mine, matric suction and volumetric water content were measured in both drying and wetting processes using Automated Soil-Water Characteristics Curve Apparatus. Based on the measured result, Soil Water Characteristic Curves (SWCC) were estimated by van Genuchten model. According to the unsaturated soil classification method, the tailings of the waste dump correspond to clayey sand. As a result of Suction Stress Characteristic Curve (SSCC) by Lu and Likos model, SSCC has a shape of S which is similar to SWCC. The hysteresis phenomenon occurred in SSCCs, which means the suction stress of drying path is larger than that of wetting path in the same effective degree of saturation. The effective stress of unsaturated soil is equal to that of saturated soil when matric suction is less than Air Entry Value (AEV). However, the effective stress of unsaturated soil is larger than that of saturated soil when matic suction is more than AEV. Meanwhile, unsaturated hydraulic conductivity by van Genuchten model decreased with increasing matric suction, and the hydraulic conductivity of drying path is larger than that of wetting path.

• Korean Journal of Agricultural Science
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• v.13 no.2
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• pp.227-242
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• 1986

This paper describes the observed behavior in the direct shear test on decomposed granite soil having the complicate engineering properties at various different levels of factors. The objectives of this study were to investigate the characteristics of the decomposed granite soil under controlled various moisture content, dry density, strain rate and soaking which give influence to the shear strength. The results were summarized as follows; 1. The shear strength was decreased remarkably with the increasing of moisture contents of A and B soil were 5-10% and 15-20% respectively. 2. Cohesion and angle of internal friction were decreased with the increasing of moisture content and increased with the increasing of dry density. 3. The shear strength was increased with the increasing of normal stress and volume change was decreased on the whole. The shear strength was generally increased with the increasing of the strain rate. 4. As dry density increases, A-soil shows the progressive failure and the decrease of volume change while B-soil shows the initial failure and the increase of volume change. 5. The relationships between the soaked and unsoaked specimens were as follows ; ${\tau}_f=0.1009+1.026{{\tau}_f}^*$ (A-soil), ${\tau}_f=0.1586+0.8005{{\tau}_f}^*$ (B-soil) 6. Angle of internal friction of the direct shear test shows larger value than that of the triaxial compression test. All effective stress path was nearly similar.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.1
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• pp.167-176
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• 1991

Finite element programs are developed, adopting the hyperbolic model and the Cam-clay model. In the hyperbolic model, a new model taking into account the volume change during shear is proposed and a new technique considering the density change underneath a footing is proposed. And a computing algorithm considered as more reasonable than existing one is presented. In the Cam-clay model, the deveoloped program is applied to sand, the case not recorded much, and then it is tried to analiza the behavior of sand from the viewpoint of the critical state concept. For this, the conventional CD triaxial compression tests and the footing model tests are carried out. The results are improved by 60 percent by using the modified hyperbolic model proposed. When the Cam-clay model is applied to sand, a model reflecting the overconsolidation effects and a computing algorithm accounting for the strain softening are needed. The results obtained by using the Cam-clay model are not much influenced by the value of the initial poisson's ratio, but those of the modified hyperbolic model are much influenced by that. So th values of the initial poisson's ratio must be selected deliberately in the numerical analysis.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.345-356
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• 2004

A plasticity model was developed to predict the behavioral characteristics of concrete in multiaxial compression. To extend the applicability of the proposed model to concrete in various stress states, a new approach for failure criteria was attempted. A stress was decomposed into one volumetric and two deviatoric components orthogonal to each other. Three failure criteria wire provided independently for each stress component. To satisfy the three failure criteria, the plasticity model using multiple failure criteria was Implemented. Each failure surface was defined by equivalent volumetric or deviatoric plastic strain. To present dilatancy due to compressive damage a non-associative flow nile was proposed. The proposed model was implemented to finite element analysis, and it was verified by comparisons with various existing test results. The comparisons show that the proposed model predicted well most of the experiments by using three independent failure criteria.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.161-171
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• 1993

The aim of this study is to provide the stress-strain behavior of hardening geological materials such as rock or concrete on three dimensional spaces by using Desai model based on plastic theory. To validate proposed model, truly triaxial tests with high pressure under variety of stress paths in which three principal stresses were controlled independently using concrete materials were performed. The main results are summerized as follows: 1. Various stress paths for hardening materials used are satisfactorily explained by performing the truly triaxial test with high pressure. This is very important to investigate constitutive equations for materials like rock or concrete. 2. Since the proposed yield function is continuous, it avoids the singularity point at the intersection of two function in the previous models, thus, reducing the difficulties for computer implementation. 3. Analytic predictions for yielding behavior on $J_1-{\sqrt{J_{2D}}}$ octahedral and triaxial plane, as well as volumetric strain and stress-strain behavior agree well with experimental results.