• Journal of Industrial Technology
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• v.24 no.A
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• pp.139-155
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• 2004

A room and pillar mining method has been adopting at the Jeungsun limestone mine. To check stability of pillar with multiple and irregular openings, the size, shape and spacing of rib pillar were first designed using some empirical suggestions. The Finite Difference Method(FDM)was used to analyze the pillar stability. Twelve different cases with the variation of K(horizontal/vertical stress)values, different height and different spacing of pillar were used in this study. Finally Mohr-Coulomb criterion was adopted to calculate the safety factors. Horizontal and vertical displacement, maximum and minimum principal stresses, range of plastic zone and safety factors were calculated at each case. As a result of analysis, the size of one block is 160m long, 70m wide, 40m high with 20m wide rib pillar and 20m square column pillar. The overall recovery at this case can be estimated about 40%.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2057-2063
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• 2011

Recently, concrete slab track is mostly used to satisfy requirements for safety of high-speed train operation and economical efficiency of maintenance. Due to structural characteristics of ballast track structures, roadbeds under the ballast experience a state of high stress. In case of slab track structures, however, its roadbeds place on a condition of low stress less than roadbeds of ballast track structures as increasing of the loading area. In this study, vertical earth pressure under slab track structures was investigated through real-scale loading tests and theoretical analysis to compare with each other.

• Transactions of Materials Processing
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• v.31 no.2
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• pp.51-56
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• 2022

In this study, finite element analyses were performed by applying a stress ring and split die design to relieve the tensile stress acting on the die due to high surface pressure during warm-closed forging. The applied material was a yield-ratio-control-steel (YRCS). It was used without quenching or tempering after forging. In the case of stress rings design, the number of stress rings and the tolerance for shrink fit were different. Vertical and horizontal splits were applied for insert die split design. Case 5 die with three stress rings, 0.2 % shrink fit tolerance, and vertical split was selected as an effective die design for tensile stress reduction. Based on die stress reduction analyses, Case 5 die for warm-closed forging was produced and smooth forgeability was secured, making it possible to manufacture forging product of yoke with the required geometry. In addition, controlled cooling using warm forging heat was applied to secure mechanical properties of yokes. When oil cooling was used for direct controlled cooling after warm-closed forging, a relatively uniform Rockwell hardness distribution and high mechanical properties could be obtained.

• The Journal of Advanced Prosthodontics
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• v.13 no.6
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• pp.396-407
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• 2021

PURPOSE. Zirconia has exceptional biocompatibility and good mechanical properties in clinical situations. However, finite element analysis (FEA) studies on the biomechanical stability of two-piece zirconia implant systems are limited. Therefore, the aim of this study was to compare the biomechanical properties of the two-piece zirconia and titanium implants using FEA. MATERIALS AND METHODS. Two groups of finite element (FE) models, the zirconia (Zircon) and titanium (Titan) models, were generated for the exam. Oblique (175 N) and vertical (175 N) loads were applied to the FE model generated for FEA simulation, and the stress levels and distributions were investigated. RESULTS. In oblique loading, von Mises stress values were the highest in the abutment of the Zircon model. The von Mises stress values of the Titan model for the abutment screw and implant fixture were slightly higher than those of the Zircon model. Minimum principal stress in the cortical bone was higher in the Titan model than Zircon model under oblique and vertical loading. Under both vertical and oblique loads, stress concentrations in the implant components and bone occurred in the same area. Because the material itself has high stiffness and elastic modulus, the Zircon model exhibited a higher von Mises stress value in the abutments than the Titan model, but at a level lower than the fracture strength of the material. CONCLUSION. Owing to the good esthetics and stress controllability of the Zircon model, it can be considered for clinical use.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.2
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• pp.146-152
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• 2014

The temperature dependence of strain-enhanced electron mobility in nMOSFETs is investigated by using a self-consistent Schr$\ddot{o}$dinger-Poisson solver. The calculated results suggest that vertical compressive stress is more efficient to maintain the strain-enhanced electron mobility than longitudinal tensile stress in high temperature condition.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.103-115
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• 1991

This study was executed to analyze the stress distribution of tooth, supporting structure and overdenture by two-dimensional photoelastics when 6 types of coping were inserted. Types of coping were designed to be inclined plane, short dome, medium dome, shore square, medium square and o-p anchor attachment. Fortes were applied respectively as follows: 1) Vertical load of 10 kg on the incisal edge 2) $30^{\circ}$ diagonal load of 8 kg on the labial surface. The results were as follows: 1. In case of short dome and o-p anchor attachment, the stress is evenly distributed on teeth, supporting tissue structure under vertical and $30^{\circ}$ diagonal load, then short dome and o-p anchor attachment show better stress distribution and stabilization of overdenture than any other coping under labial diagonal load. 2. Inclined plane revealed greater tendency of displacement of overdenture than any other coping under labial diagonal load. 3. Long height of copings had greater concentration of stress than short height of copings. 4. In case of medium dome under labial diagonal load, there were high level of stress concentration on denture base contacted labioincisal angle of coping.

• International Journal of High-Rise Buildings
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• v.6 no.1
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• pp.73-82
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• 2017

Vertical shortening in tall buildings would be of little concern if all vertical elements shortened evenly. However, vertical elements such as walls and columns may shorten different amounts due to different service axial stress levels. With height, the differential shortening may become significant and impact the strength design and serviceability of the building. Sometimes column transfers or other vertical structural irregularities may cause differential shortening. If differential shortening is not addressed properly, it can impact the serviceability of the building. This paper takes the perspective of a structural engineer in planning the design, predicting the shortening and its effects, and communicating the information to the contractor.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.5
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• pp.584-593
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• 2006

Statement of problem : Dental implant which has been developed gradually through many experiments and clinical applications is presently used to various dental prosthetic treatments. To conduct a successful function of implant prosthesis in oral cavity for a long time, it is important that not only structure materials must have the biocompatibility, but also the prosthesis must be designed for the stress, which is occurred in occlusion, to scatter adequately of load support. Therefore, it is essential to give the consideration about the stress analysis of supporting tissues for higher successful rates. Purpose : Recently, many implant manufacturing company produce various taper design of root form implant, the fixture is often selected. However, the stress analysis of taper form fixture still requires more studies. Material and method : This study we make the element models that five implant fixture; Branemark system(Nobel Biocare, Gothenberg, Sweden), Camlog system(Altatec, Germany), Astra system(Astra Tech, Sweden), 3i system(Implant Innovations Inc, USA), Avana system(Osstem, Korea) were placed in the area of mandibular first premolar and prosthesis fabricated, which we compared with stress distribution using the three-dimension finite element analysis under two loading condition. Results : This study compares the aspect of stress distribution of each system with the standard of Von mises stress, among many resulted from finite element analysis so that this research gets the following results. 1. In all implant system, oblique loading of maximum Von mises stress of implant, alveolar bone and crown is higher than vertical loading of those. 2. Regardless of loading conditions and type of system, cortical bone which contacts with implant fixture top area has high stress, and cancellous bone has a little stress. under the vertical loading, maximum Von mises stress is more higher in order of Branemark, Camlog, Astra, 3i, Avana. under the horizontal loading, maximum Von mises is more higher in order of Camlog, Branemark, Astra, 3i, Avana.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.3
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• pp.337-351
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• 2019

We Proposed a new technology to develop vertical type multi-joint robot system enable to adapt in high temperature environment. The main contents is a new approach to design a vertical type articulated robot with prismatic joint and analysis of thermal for process automation of casting and forging. The proposed robot is suitable to use handling working parts of casting and forging. for the manufacturing process of forging and casting. The reliability is illustrated that the proposed technique is more stable and robust than the conventional system. This study is concerned with an analytical methodology of kinematic computation for 7 DOF manipulators for optimization of forging manufacturing process.

• Journal of Korean Society of Steel Construction
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• v.29 no.3
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• pp.237-247
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• 2017

This paper investigates structural characteristics of internal vertical diaphragm and its influence on the connection strength between concrete filled tubular(CFT) column and beam. CFT columns are hybrids that combine two materials in one member. They have the benefits of steel for high tensile strength and ductility and of concrete for high compressive strength and stiffness. Analytical method of the flexural strength of vertical diaphragm to account moment transfer between panel zones is presented using yield line theory. Connection design is verified by a set of monotonic tests and numerical analysis with different diaphragm thicknesses. Plastic zones of CFT flange was found and matched closely to FEM results. Both analytical and experimental results showed good agreement that vertical diaphragm effectively alleviates the stress and transfer the force.