• Earthquakes and Structures
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• 제16권2호
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• pp.221-234
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• 2019

Today, many important concrete face rockfill dams (CFRDs) have been built on the world, and some of these important structures are located on the strong seismic regions. In this reason, examination and monitoring of these water construction's seismic behaviour is very important for the safety and future of these dams. In this study, the nonlinear seismic behaviour of Ilısu CFR dam which was built in Turkey in 2017, is investigated for various reservoir water heights taking into account 1995 Kobe near-fault and far-fault ground motions. Three dimensional (3D) finite difference model of the dam is created using the FLAC3D software that is based on the finite difference method. The most suitable mesh range for the 3D model is chosen to achieve the realistic numerical results. Mohr-Coulomb nonlinear material model is used for the rockfill materials and foundation in the seismic analyses. Moreover, Drucker-Prager nonlinear material model is considered for the concrete slab to represent the nonlinearity of the concrete. The dam body, foundation and concrete slab constantly interact during the lifetime of the CFRDs. Therefore, the special interface elements are defined between the dam body-concrete slab and dam body-foundation due to represent the interaction condition in the 3D model. Free field boundary condition that was used rarely for the nonlinear seismic analyses, is considered for the lateral boundaries of the model. In addition, quiet artificial boundary condition that is special boundary condition for the rigid foundation in the earthquake analyses, is used for the bottom of the foundation. The hysteric damping coefficients are separately calculated for all of the materials. These special damping values is defined to the FLAC3D software using the special fish functions to capture the effects of the variation of the modulus and damping ratio with the dynamic shear-strain magnitude. Total 4 different reservoir water heights are taken into account in the seismic analyses. These water heights are empty reservoir, 50 m, 100 m and 130 m (full reservoir), respectively. In the nonlinear seismic analyses, near-fault and far-fault ground motions of 1995 Kobe earthquake are used. According to the numerical analyses, horizontal displacements, vertical displacements and principal stresses for 4 various reservoir water heights are evaluated in detail. Moreover, these results are compared for the near-fault and far-faults earthquakes. The nonlinear seismic analysis results indicate that as the reservoir height increases, the nonlinear seismic behaviour of the dam clearly changes. Each water height has different seismic effects on the earthquake behaviour of Ilısu CFR dam. In addition, it is obviously seen that near-fault earthquakes and far field earthquakes create different nonlinear seismic damages on the nonlinear earthquake behaviour of the dam.

• Computers and Concrete
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• 제18권6호
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• pp.1153-1173
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• 2016

According to deformation data measured in some high concrete dams, for dam body deformation, there is a complex relationship with dam height and water head for different projects, instead of a simple monotonic relationship consistently. Meanwhile, settlement data of some large reservoirs exhibit a significant deformation of reservoir basin. As water conservancy project with high concrete dam and large storage capacity increase rapidly these decades, reservoir basin deformation problem has gradually gained engineers' attentions. In this paper, based on conventional analytical method, an improved analytical method for high concrete dam is proposed including the effect of reservoir basin deformation. Though establishing FEM models of two different scales covering reservoir basin and near dam area respectively, influence of reservoir basin on dam body is simulated. Then, forward and inverse analyses of concrete dam are separately conducted with conventional and proposed analytical methods. And the influence of reservoir basin deformation on dam working behavior is evaluated. The results of two typical projects demonstrate that reservoir basin deformation will affect dam deformation and stress to a certain extent. And for project with large and centralized water capacity ahead of dam site, the effect is more significant than those with a slim-type reservoir. As a result, influence of reservoir basin should be taken into consideration with conducting analysis of high concrete dam with large storage capacity.

• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1221-1230
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• 2008

Inflatable rubber dams are used for controlling flood, impounding water for recreations, preventing beach erosions, diverting water for irrigations, and generating hydropower. They are long, flexible, inflated with air, cylindrical structures on a rigid horizontal foundation such as concrete. The dam is modeled as an elastic shell inflated with air. The mechanical behaviors of the inflated dam model were investigated by using the finite element method. The analysis process such as One Way Coupling Fluid-Structure Interaction consists of two steps. First, the influences of the fluid side were investigated, viz, the shape changes of the inflated rubber dam due to the fluid motions was captured when the height of the dam was 30cm with air pressure 0.01MPa, at which the pressure distributions over the surface of the dam were calculated. And next, the structural deformations were calculated using the pressure distributions. The initial inlet velocity for flow field was set to 0.1m/s. The structural deformation behaviors were investigated. The final research goal is to develop a Korean Inflatable Rubber Dam to be used for generating small hydropower.

• Structural Engineering and Mechanics
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• 제72권2호
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• pp.141-153
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• 2019

The effect of galleries on the earthquake behavior of dams should be investigated to obtain more realistic results. Therefore, a roller compacted concrete (RCC) dam with and without galleries are examined under ground motion effects. For this purpose, Cine RCC dam constructed in Aydın, Turkey, is selected in applications. The optimal mesh around galleries is investigated to obtain the most realistic results. Two-dimensional finite element models of Cine RCC dam with and without galleries are prepared by using ANSYS software. Empty and full reservoir conditions were taken into account in the time-history analyses. Hydrodynamic effect of the reservoir water was taken into account considering two-dimensional fluid finite elements based on the Lagrangian approach. It is examined that how principle stresses and displacements change by height and during earthquake. The dam-foundation-reservoir interaction was taken into consideration with contact-target element pairs. The displacements and principle stress components obtained from the linear analyses are compared each other for various cases of reservoir water and galleries. According to numerical analyses, the effect of galleries is clear on the response of RCC dam. Besides, hydrodynamic water effect obviously increases the principle stress components and horizontal displacements of the dam.

• 한국농공학회지
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• 제31권1호
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• pp.82-95
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• 1989

This study was carried out for the stability analysis of earth dam by the variation of compaction density. The test samples were taken from five kinds of soil used for banking material and the degree of compaction for this samples were chosen 100, 95, 90, 85, and 80 percent. The stability problems were analysed by the settlement and camber( extra banking) of dam, strength parameter and dam slope, and coefficient of permeability and seapage flow through dam body. The results of the stability analysis of earth dam are as follows. 1. The more the fine particle increases and lower the compaction degree becomes, the lower the preconsolidation load becomes but the compression index becomes higher. 2. Sixty to eighty percent of settlement of dam occurs during the construction period and the settlement ratio after completion of dam is inversly proportional to the degree of compaction. 3. The camber of dam has heigher value in condition that it has more fine particle(N) and heigher dam height(H) with the relation of H= e(aN-bH-e). 4. The cohesion(C) decreases in proportion to compaction degree(D) and fine particle(N) with the relation of C= aD+ bN-c, but the internal friction angle is almost constant regardless of change of degree of compaction. 5. In fine soil, strength parameter from triaxial compression test is smaller than that from direct shear test but, they are almost same in coarse soil regardless of the test method. 6. The safety factor of the dam slope generally decreases in proportion to cohesion and degree of compaction but, in case of coarse soil, it is less related to the degree of compaction and is mainly afected by internal friction angle. 7. Soil permeability(K) decreases by the increases of the degree of compaction and fine particle with relation of K=e(a-bl)-cN) 8. The more compaction thickness is, the less vertical permeability (Kv) is but the more h6rzontal permeability (KH) is, and ratio of Kv versus KH is largest in range from 85 to 90 percent of degree of corn paction. 9. With the compaction more than 85 percent and coefficient of permeability less than ${\alpha}$X 10-$^3$cm/sec, the earth dam is generally safe from the piping action.

• Geomechanics and Engineering
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• 제31권6호
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• pp.637-651
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• 2022

The seismic design of embankment dams requires more comprehensive studies to understand the behaviour of dams. Deformations primarily control this behaviour occur during or after earthquake loading. Dam failures and incidents show that the impacts of deformations should be reviewed for existing and new embankment dams. Overtopping erosion failure can occur if crest deformations exceed the freeboard at the time of the deformations. Therefore, crest settlement is one of the most critical deformations. This study developed empirical formulas using Gene Expression Programming (GEP) based on 88 cases. In the analyses, dam height (H_d), alluvium thickness (H_a), the magnitude-acceleration-factor (MAF) values developed based on earthquake magnitude (Mw) and peak ground acceleration (PGA) within this study have been chosen as variables. Results show that GEP models developed in the paper are remarkably robust and accessible tools to predict earthquake-induced crest settlement of embankment dams and perform superior to the existing formulation. Also, dam engineering professionals can use them practically because the variables of prediction equations are easily accessible after the earthquake.

• 한국지반환경공학회 논문집
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• 제18권3호
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• pp.31-38
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• 2017

본 연구의 목적은 지반공학적 물성정보가 거의 없는 국내 중소규모 댐의 지진 시 파괴확률을 간편하게 산정할 수 있는 도표를 제시하는 것이다. 기존의 댐의 지진 시 파괴확률을 산정하는 방법 및 절차를 검토하여, 댐의 지반공학적 물성정보와는 상관없이 지진 시 파괴확률이 '0'이 되는 지진파괴확률 영곡선을 댐높이-여유고율 평면에서 쌍곡선의 형태로 결정하였다. 국내 중소규모 댐들의 댐높이-여유고율 분포형태가 지진파괴확률 영곡선과 같이 쌍곡선의 형태를 이루는 것을 확인하여, 다수의 등파괴확률 곡선(seismic failure probability contour)이 댐높이-여유고율 평면에서 일정한 간격의 다수의 쌍곡선들로 표시되는 지진파괴확률 산정 도표를 작성하였다. 작성된 도표는 비교적 관리가 잘 되고, 지반공학적인 정보를 충분히 가진 2개의 중소규모 댐들의 지진 시 파괴 확률 산정에 적용하여, 기존 절차와 방법으로 산정된 결과와 비교하여 적용 타당성을 확인하였다. 향후, 제안된 도표는 중소규모댐의 지진대비 보수보강의 투자 우선순위 등을 고려할 때 유용하게 활용될 수 있을 것으로 기대된다.

• 대한치과기공학회지
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• 제24권1호
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• pp.107-126
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• 2002

The first function of occlusion is mastication. Therefore the functional restoration of occlusal surface is very important. The restoration of occlusal surface is three method as wax bite technique, F.G.P. technique, cone technique. Many dental technician is using compound method. I am using compound method of wax bite technique and cone technique. I have knew common point on each teeth during I have waxing up wax pattern. So I studied on the design waxup technique for mandible molar occlusion. The results of the study were as follows; 1. The dam wax up method can restore axial contour of teeth very easy and make short working time of wax pattern. 2. The height of dam must be same with cusp of adjacent teeth. 3. Automatically the contour of tooth is appeared if the contour of dam is relationship with cuspid line of adjacent teeth. 4. The height of contour of buccal, lingual surface is formed natural curve to add fluid wax by gravitation. 5. The development groove of mandible first premolar is appeared V form. 6. The development groove of mandible second premolar is appeared Y form. 7, The development groove of mandible first molar is appeared M form. 8. The development groove of mandible second molar is W form. 9. The embrasure is formed to carve around contact point area as round convex. It affects to axial form of tooth. 10. The buccal, lingual groove of molar is formed parallel with direction of teeth arrangement.

• 대한치과기공학회지
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• 제21권1호
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• pp.97-114
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• 1999

The first function of occlusion is mastication. Therefore the functional restoration of occlusal surface is very important. The restoration of occlusal surface is three method as wax bite technique, F.G.P. technique, cone technique. Many dental technician is using compound method. I have knew common point on each teeth during I have waxing up wax pattern. So I studied on the design waxup technique for maxillary molar occlusion. The results of the study were as follows ; 1. The dam wax up method can restore axial contour of teeth very easy and make short working time of wax pattern. 2. The height of dam must be same with cusp of adjacent teeth. 3. Automatically the contour of tooth is appeared if the contour of dam is relationship with cuspid line of adjacent teeth. 4. The height of contour of buccal, lingual surface is formed natural curve to add fluid wax by gravitation. 5. The development groove of Maxillary premolar is appeared V form. 6. The development groove of Maxillary molar is appeared W form. 7. The embrasure is formed to carve around contact point area as round convex. It affects to axial form of tooth. 8. I was knew that the lingual groove and stuart's groove of molar runs parallel with oblique ridge. 9. The buccal groove of molar is formed parallel with direction of teeth arrangement.

• 한국해양공학회지
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• 제21권1호
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• pp.25-30
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• 2007

Most of dams and reservoirs were made from natural materials, such as soil, sand and gravel. This type of hydraulic structure has the danger of collapse by overflow during a flood. Freeboard is the vertical distance between the crest of the dam and the full supply level in the reservoir. It must be sufficient to prevent overtopping from over flow. Thus, freeboard determination involves engineering judgment, statistical analysis, and consideration of the damage that would result from the overtopping of a hydraulic structure. This study attempts to calculate the wave height in dam, which is needed for the determination of the freeboard of the dam. Chung-ju dam is selected as the study area. Using the empirical formulas, the wave heights in dam were calculated, and the results were compared with those by the SWAN model, which is a typical wave model. The difference between the calculated results from the empirical formulas and those by the SWAN model is considerably large. This is because empirical equations consider only fetch or fetch and wind velocity, while the SWAN model considers depth and topography data as well.