• Geotechnical Engineering
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• v.14 no.3
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• pp.73-94
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• 1998

In the present study, a method of the three-dimensional limit equilibrium stability analysis of shape of the potential failure wedge for the concave-shaped excavation corner is assumed on the basis of the results of the FLACSU program analysis. Estimation of the three-dimensional seepage forces expected to act on the failure wedge is made by solving the three-dimensional continuity equation of flow with appropriate boundary conditions. By using the proposed method of three-dimensional stability analysis of the concave-shaped excavation corner, a parametric study is performed to examine the reinforcement effect of skew soil nailing system, range of the efficient skew angles and seepage effect on the overall stability. Also examined is the effect of an existence of the right-angled excavation corner on three-dimensional deflection behaviors of the convex-shaped skew soil nailing walls. The results of analyses of the convexshaped excavation corner with skew soil nailing system is further included to illustrate the effects of various design parameters for typical patterns of skew nails reinforcement system.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.41-52
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• 2018

Since the composite ground design method is easy to apply for calculation or numerical analysis, it is applied to the design of cement mixing methods. However, the comparison studies between analysis and actual results such as a trial test and construction for the cement mixing method are few because the composite ground design method was developed for the compaction pile (SCP, GCP) methods. In this study, the results of various analysis methods, such as the composite ground analysis method (1 case) and the individual pile method (3 cases), were compared with actual measurements through a two-dimensional finite element numerical analysis. In case of the surface settlements, the results of study show that the individual plate method was larger than the actual measurements, while other methods are similar. The settlements at the under ground of the improved area is overestimated in all analysis methods. When comparing numerical analysis results for the horizontal displacement, and ground reaction forces, the individual pile method in equivalent wall concept was found to be the most similar to the measurements. The composite ground method was not able to predict the behavior of stress transfer (Arching effect) and it turned out that the prediction of horizontal displacement was too large.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.3
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• pp.255-265
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• 2009

Recently many studies have been published on application of immediate loaded implants. However, the immediate loading protocol has not been well documented. The purpose of the present study was to evaluate the stress distribution between bone-implant interfaces and the effect of implant length in the anterior maxilla using 3 dimensional finite element analyses. The diameter 4.0 mm threaded type implants with different length(8.5 mm, 10.0 mm, 11.5 mm, 13.0 mm, 15.0 mm) were used in this study. The bone quality of anterior maxillary bone block was assumed to D3 bone. Bone-implant interfaces of immediately loaded implant were constructed using a contact element for simulating the non osseointegration status. For simplification of all the processing procedures, all of the material assumed to be homogenous, isotropic, and linearly elastic. The 178 N of static force was applied on the middle of the palatoincisal line angle of the abutment with $120^{\circ}$ angle to the long axis of abutment. Maximum von Mises stress were concentrated on the labial cortical bone of the implant neck area, especially at the cortical-cancellous bone interfaces. Compared the different length, highest peak stress value was observed at the 8.5 mm implants and the results indicated a tendency towards favorable stress distribution on the bone, when the length was increased. Presence of cortical bone was very important to immediate loading, and it appears that implants of a length more than 13 mm are preferable for immediate loading at the anterior maxilla.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.1
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• pp.7-11
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• 2006

Through SCM modeling, we found that the depletion layer in silicon was of a form of a spherical capacitor with the SCM tip biased. Two-dimensional (2D) finite differential method code with a successive over relaxation (SOR) solver has been developed to model the measurements by SCM of a semiconductor wafer that contains an ion-implanted impurity region. Then, we theoretically analyzed the spherical capacitor and determined the total depleted-volume charge Q, capacitance C, and the rate of capacitance change with bias dC/dV. It is very important to observe the depleted carriers' movement in the silicon layer by applying the bias to the tip. So, we calculated the depleted-volume charge, considering different factors such as tip size, oxide thickness, and applied bias (dc+ac), which have an influence on potential and depletion charges.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.229-238
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• 2009

This paper describes the methods to propose the optimal material properties and construction steps that prevent cracks due to the thermal stresses induced by the hydration heat under the construction of the concrete underpass structures. To achieve the goal of this study, the heat transfer theories were employed and the three-dimensional finite element model of the underpass structure was developed and used for the structural analyses. If the volume of the concrete member that is placed at one time is significantly large, the member is assumed to be the mass concrete and is easy to induce cracks. In order to minimize the cracks during the construction, two different methods can be utilized: one is to arrange the construction steps optimally and the other is to change the materials to reduce the probability of the crack occurrence. In this study, the analyses were performed by considering the changes in material properties with time, the characteristics of the hydration heat generation for cements and admixtures, the volume of the concrete placement at one time, and the environmental conditions.

• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.281-302
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• 1987

의치상 재료 종류에 따라 의치, 점막 및 하악골에 발생되는 변위 및 응력을 연구하기 위하여 컴퓨터를 이용한 수치적 해석인 2차원 유한 요소법을 이용하였다. 2차원 유한 요소 모형으로선 표준 크기의 하악골 및 의치를 고려하여 231개의 사변형 요소 및 268개의 절점으로 분할한 후 각 구성 성분의 물리적 성질인 탄성률 및 프와송비를 대입시켰다. 사용된 의치로서는 일반 합성수지의치, 2mm후경의 탄성재를 의치상 하부에 이장한 합성수지의치, 2mm후경의 탄성재를 치아와 의치상 중앙에 삽입한 합성수지의치 및 0.5mm후경의 금속상의치의 4종류였으며, 하중시에 하악의 고정 부위로선 생체와 동일 조건을 부여하기 위하여 교근, 내측익돌근, 측두근등의 하악 폐구근이 부착되는 하악각 부위 및 하악 근돌기 부위의 16절점을 고정점으로 하였다. 하중 조건으로선 하악 제1대구치의 일점에 10kg의 수직 집중하중, 하악 중절치의 일점에 7kg의 수직 집중하중 및 하악 제 1소구치로 부터 하악 제2대구치까지의 교합면에 10kg의 수직 분산하중을 부여하여 분석한 결과는 다음과 같다. 1. 하중이 의치 교합면위의 가해진 부위에 따라 다양한 의치 회전 및 강하 현상을 보였으며, 탄성재를 이장 및 삽입한 합성 수지 의치의 변위가 일반 합성수지의치 및 금속상 의치의 변위보다 더 컸다. 2. 주응력을 고려할때 점막 부위에는 주로 압축 응력이 작용하였으며 치조제 부위는 압축응력과 인장 응력이 함께 작용하였다. 3. 탄성재를 삽입한 합성수지의치에 최고 등가 응력이 집중되었으며 그 다음은 탄성재를 이장한 합성수지의치, 일반 합성수지의치의 순이였으며 금속상의 경우는 금속을 따라서 높은 등가 응력이 넓게 분산되었다. 4. 의치상 종류에 관계없이 동일 하중 조건하에선 점막에 나타나는 등가 응력의 크기 및 분산양태는 유사하였다. 5. 하악골에서 등가 응력은 의치지지 부위에만 국한되지 않고 넓게 분산 되었으며 의치상 종류 및 하중 조건에 관계없이 치조제 후방 및 하악연의 후방 부위에 특히 높은 등가응력이 집중되었다. 6. 하악 중절치의 일점에 수직 하중을 가한 경우가 다른 하중 조건에 비하여 지지점과의 거리차이로 인하여 하악골에 가장 높은 등가 응력을 유발하였다. 7. 의치상 재료에 따른 하악 골에 발생되는 응력의 크기 및 분산에는 큰 차이가 없으나 금속상의 경우가 교합압을 분산하는데는 효과적이었다.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.70-81
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• 2009

Statement of problem: The position and length of cantilever influence on the stress distribution of implants, superstructure and bone. In edentulous mandible, implant-supported cantilever prostheses that based 4 or 6 implants between mental foramens has been attempted. Excessive bite force loaded at cantilever prosthesis causes bone resorption and breakage of superstructure prosthesis around posterior implants. To complement the cantilever length of conventional prosthesis, In 1992, (McCartney) introduced "cantilever-rest-implant" and Malo reported "All-on-Four" in 2003. Purpose: Analyze and compare the stress distribution of conventional cantilever prostheses with rest implant and All-on-$Four^{TM}$ implant prostheses. Material and method: The external loads(300 N vertically, 75 N horizontally) are applied to first molar area. The stress value, stress distribution and aspect of stress dispersion are analyzed by three-dimensional finite element analysis program, ANSYS ver. 10.0. Results: 1. The rest implant and "All-on-Four" implant system are superior to conventional cantilever prostheses to reduce stress on the bone and the superstructure around implants. 2. The rest implant was of the greatest advantage to stress distribution on bone, implant and superstructure. 3. With same number of implants, distally tilted implants are preferred to conventional cantilever prostheses for reducing the length of cantilever.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.4
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• pp.253-262
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• 2006

In this paper, collision analysis is carried out between two FRP fishing boats. A computer simulation with finite element method is used to accomplish this objective. At first, a detailed geometric model of the boat is constructed using 3-D CAD program. The formation of a finite element from a geometric data of the boats is carried out using HYPERMESH that is the commercial software for mesh generation and post processing. Twelve collision configurations are established by combining two kinds of contact angle($90^{\circ},\;135^{\circ}$) and three different speed(5, 10, 15knot) for small and large boats. Collision analysis is accomplished using DYNA3D. Stress distribution and deformation shape are investigated for each collision condition. In general, $90^{\circ}$ collision angle generate larger stress than $135^{\circ}$ case and the collision for two moving boats showed larger maximum stress than the case that one is moving and the other is stationary. When analysis is carried out until 150ms contact parts of two boats are broken for 10 and 15knot collision speed, in which maximum stress is larger than ultimate strength of the material.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.4
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• pp.371-392
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• 2011

The purpose of this study was to comparatively analyze the stress distribution according to the inclinations of abutments and angulations of the implant fixtures under occlusal loading force. Three study models with straight and $15^{\circ}$ and $25^{\circ}$-angled abutments were prepared following the insertion of Implants parallel to the long axis of the tooth. Additional two experimental models were fabricated with $15^{\circ}$ and $25^{\circ}$ fixture inclinations. Using ANSYS 11, a finite element analysis program, the magnitudes of stress distribution were analyzed. The magnitude of stress under loading was lowest when the load was applied vertically onto the axis of implant. And the magnitude of stress under compound(vertical+oblique) loading was increased as the inclination of implant abutment and fixture was increase. But, the distribution of stress was different as the loading conditions, because of the horizontal offset. As the offset between the axis of loading and the central axis of the implant increased, the stress was increased.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.04a
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• pp.181-187
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• 1997

고강도 알루미늄 합금 링롤재의 급냉, 링 팽창(expansion) 및 링 압축(compression) 응력제거처리후 잔류응력을 예측하기 위하여 2차원 축대칭 열해석 및 탄소성 해석을 수행하였다. 급냉 및 응력제거처리 후 2단 과시효 처리(T73)된 링롤재에 대하여 3단계 절단법(Three step sectioning method)을 적용하여 링롤재의 두께에 따른 잔류응력 분포를 측정하였으며, 측정결과를 급냉 및 응력제거처리후 잔류응력 해석결과와 비교분석하였다. 링의 급냉후 원주 및 축방향의 잔류응력 해석값은 T73후 측정값과 비슷한 경향을 보였으며, 링의 내면과 외면에서 압축응력을 나타내었고 중심에서 인장응력을 나타내었다. 잔류응력은 링 팽창(T7351) 및 링 압축(T7352) 적용후 T73에 비해 현저히 감소하였으며, 축방향의 제거 효과가 원주방향보다 우수하게 나타났다. 또한 링 압축에 의한 제거효과가 링 팽창보다 크게 나타났다. 링롤재의 응력제거처리는 제거 효과 및 실용성 측면에서 링 압축 공정이 유리하며, 치수제어 및 장비용량 측면에서 링 팽창 공정이 유리하다는 결론을 얻었다.