• The Journal of Korean Academy of Prosthodontics
• /
• v.35 no.1
• /
• pp.181-210
• /
• 1997

The stress distribution generated in the surrounding bone was calculated and compared for various geometry of the dental implants by means of the finite element methods. The models were designed to represent the screw type endosseous implants(varing the size, shape, direction of the screw thread and the angle of the body) with supporting bone and the cylinder type endosseous implants(varing the lower portion-Round type, tapered type) with supporting bone. Static mean bite forces were applied 100N vertically and 25N horizontally on the center of the implant and three dimensional finite analysis was undertaken using software ANSYS 5.1 Version. The result demonstrated that different implant shape leads to significant variations in stress distribution in the bone. In the case of variation of the screw size, direction and shape the implant model with normally directional and triangular screw implied lower stress than with upper directional or lower directional and quadrangular screw but among models a different screw size, within a variation of 0.2mm there was no meaningful difference in maximum stress. In the case of variation of angle of body the straight implied lower stress than the tapered. As a result of analysis of cylinder type, the implants with larger radius of curvature of the round form and larger diameter of the tapered form implied lower stress.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.9
• /
• pp.1359-1367
• /
• 2004

The purpose of this study is to predict the dynamic transmission error of the helical gear system. To do so, the equations of motion in the helical gear system which consists of motor, coupling, gear, torque sensor, and brake are derived. As the input parameters, the mass moment of inertia by a 3D CAD software and the equivalent stiffness of the bearings and shaft are calculated and the coupling stiffness is measured. The static transmission error as an excitation is calculated by in-house program. Dynamic transmission error is predicted by solving the equations of motion. Mode shape, the dynamic mesh force and the bearing force are also calculated. In this analysis, the relationship between the dynamic mesh force and the bearing force and mode shape behavior in gear mesh are checked. As a result, the magnitude of mesh force is highly related with the gear mesh behavior in mode shape. The finite element analysis is conducted to find out the natural frequency of gear system. The natural frequencies by finite element analysis have a good agreement with the results by equation of motion. Finally, dynamic transmission error is measured by the specially designed experiment and the results by equation of motion are validated.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.11a
• /
• pp.174-175
• /
• 2005

The purpose of this study is focused on the analysis of 3D complex flow and performance characteristics of a centrifugal pump with volute casing. The numerical analysis was performed by commercial code CFX-10 according to the variation of flow rate, which is changing from 5.847$m^3$/min to 6.865$m^3$/min. The rated rotational speed of close type impeller is 1750rpm. Turbulence model, k-${\omega}$ SST was selected to guaranty more accurate prediction of flow separation. The ICEM-CFD 10, reliable grid generation software was also adapted to secure high quality grid generation necessary for the reliable numerical simulation. The experimental results such as static head, brake horse power and efficiency of the centrifugal pump were compared with the numerical analysis results. The simulated results are good agreement with the experimental results less 5$%$ error.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.12 no.5
• /
• pp.109-115
• /
• 2013

In this study, a variable swash plate compressor has been used in a vehicle to improve its fuel efficiency. To manufacture the swash plate, either SCM 435 or UNS C67300 was used. The effects of using different materials for the structural reliability of compressor have been investigated. Static analysis was carried out on swash plate A/C compressor by using commercial software ANSYS 13.0v. The results showed that the Max. stress occurred on the swash plate made of UNS C67300 was lower than that made of SCM435, which indicated that UNS C67300 is more suitable for producing the safe swash plate.

• Structural Engineering and Mechanics
• /
• v.50 no.1
• /
• pp.1-17
• /
• 2014

In this paper, overstrength, ductility and response modification factors are calculated for frames braced with a different type of buckling restrained braces, called reduced yielding segment BRB (Buckling Restrained Brace) in which the length of its yielding part is reduced and placed in one end of the brace element in comparison with conventional BRBs. Forthermore, these factors are calculated for ordinary BRBF and the results are compared. In this regard incremental dynamic analysis (IDA) method is used for studying 17 records of the most known earthquakes happened in the world. To do that, the considered buildings have different stories and two bracing configurations: diagonal and inverted V chevron, the most ordinary configurations of BRBFs. Static pushover analysis, nonlinear incremental dynamic analysis and linear dynamic analysis have been performed using OpenSees software. Considering the results, it can be seen that, overstrength, ductility and response modification factors of this type of BRBF(Buckling Restrained Braced Frame) is greater than those of conventional types and it shows better seismic performance and also eliminates some of conventional BRBF's disadvantages such as low post-yield stiffness.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.3
• /
• pp.230-236
• /
• 2020

A trash screen is installed in front of the inflow channel of a drainage pumping station, sewage treatment plant, and a power plant to block floating contaminants. The bottleneck phenomenon, which decreases the water inflow, causes damage to the damper as a result of clogging in between the screen if string type obstacles are not removed. In this paper, the apron was removed, and the screen was expanded, to prevent breakage of the bottleneck phenomenon and string type obstacles. This was designed using an extended rake by adding an inner rake in between the screen interspace to remove the bottleneck phenomenon and string type obstacles. To design the inner rake that satisfies the allowable stresses of the existing damper rake, the experiment points were determined according to the experimental design method using the inner rake vertical length and the thickness of the reinforced section as parameters. The use of the ANSYS static structural module and statistical analysis tool R software gives the optimized shape according to the response surface method. The relative error between the response surface analysis results and the simulation results was 1.63% of the determined optimal design-point rake length of 210.2 mm and the reinforcement section thickness of 2 mm. Through empirical experiments, a test rake was constructed to the actual size, and approximately 97% of the bottleneck phenomenon and string type obstacles could be removed.

• Proceedings of the KIEE Conference
• /
• 1996.07a
• /
• pp.594-596
• /
• 1996

Static power converters can be analyzed by means of available circuit simulation software packages such as PSPICE. This paper proposes the macro models developing technique for three-phase power converters using the transfer function approach. Also, these models are based on converter switching functions rather than actual circuit configuration. In this approach, VSI(Voltage Source Inverter) and CSI(Current Source Inverter) are simulated as multiport networks avoiding nonlinear macromodels of the power switches.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.8
• /
• pp.1052-1063
• /
• 1998

The performance database of small-sized centrifugal compressors is needed for the design of high performance machines and also for the verification of design tools and analysis software. An impeller is designed, manufactured and tested. The effects of several parameters on the evaluation of performance are investigated and the performance test of parallel diffuser is also carried out. The proper estimation of static pressure, total temperature and blockage at the impeller exit is important for performance evaluation. 4 method in cooperation with 3-D calculation is suggested. The measured performances are in a good agreement with the predicted results. However, there are some discrepancies in efficiency.

• Journal of the Korean Society of Systems Engineering
• /
• v.11 no.1
• /
• pp.67-72
• /
• 2015

It has been tested for SW reliability in order to prevent the SW error during the development of weapons systems. According to a recent report, defects such as memory leak, buffer overflow, and null deference occur usually in the development stage, but also in the mass production stage. Although it is intended to enhance the SW test and evaluation to prevent SW failures in the development stage, the non-functional problems like syntax errors are not completely revised due to the limitation of the schedule and costs. In addition, SW failure rate are usually fluctuated by the operational environment through SW upgrade in contrast with HW. In this paper, we propose a method to increase SW reliability in the mass production stage of Korean weapon systems.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.775-779
• /
• 2007

The structural strength assessment of a carbody was performed using F.E. analysis and static test to verify the structural safety of newly manufactured carbody of a freight car. The freight car for the transportation of cold-rolled coils in steel making company was designed with SS400 steel for underframe and SM490A steel for bracket. Prior to the evaluation of structural strength, commercial finite element method(FEM) software was used for the stress and structural analyses on stress distribution in a carbody of freight car. The strain gages were attached on the carbody based on the FEM results. The actual vertical loading test and horizontal compression loading test were conducted, and the stress and displacement were obtained. Finally, the structural strength of carbody was evaluated by using a engineering techniques.