• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2004.04a
• /
• pp.151-160
• /
• 2004

Genetic algorithm is the theory of grafting the principle of survival of the fittest in genetics on to the computer algorithm and it is used to solve the optimization problems, especially the shape and size optimization of the structure in Architectural problems. In the size optimization problem discrete variables are used, but series variables have to be used in the shape optimization problem because of the incongruenty. The purpose of this study is to obtain the optimum shape of cable domes by using the real coding genetic algorithm. Generally, the structural performance of the cable domes is influenced very sensitively by pre-stress, geometry and length of the mast because of its flexible characteristic. So, it is very important to decide the optimum shape to get maximum stiffness of cable domes. We use the model to verify the usefulness of this algorithm for shape optimization and analyze the roof system of Seoul Olympic Gymnastic Arena as analytical model of a practical structures. It is confirmed lastly that the optimum shape domes have more stiffness than initial shape ones.

• Transactions of Materials Processing
• /
• v.8 no.4
• /
• pp.356-363
• /
• 1999

This paper discusses some techniques for the determination of optimum blank size and pre-form design for multi-stepped deep drawing of oval shell. The deep drawing process of oval shape has been regarded as more difficult than that of cylindrical shell because of its complicated behavior of plastic deformation. But there is insufficient information in this area to carry out successful deep drawing work of irregular products such as oval, rectangular, and square shapes. In order to find the optimum conditions, the drawing apparatus for two kinds of pre-form design are built, a series of drawing experiments performed, and thickness stain distributions measured. From the results of thess suggested experiments, various optimum process variables are observed and discussed.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.909-914
• /
• 2001

It is important to consider an effect of concrete member sizes when estimating the ACI rectangular stress block of a reinforced concrete flexural member. However, the experimental data and analytical analyses are still not available for a proper evaluation. For all types of loading conditions, the trend is that the size of an ACI rectangular stress block tends to change when the member sizes change. In this paper, the size variations of strength coefficients for ACI rectangular stress block and actual stress distribution have been studied. Results of a series of C-shaped specimens subjected to axial compressive load and bending moment were adopted from references 1 and 2. The analysis results show that the effect of specimen sizes on strength coefficients for ACI rectangular stress block and actual stress distribution of concrete member was apparent. Thus, the results suggest that the current strength criteria based design practice should be reviewed.

• Journal of Korean Society for Quality Management
• /
• v.27 no.3
• /
• pp.51-66
• /
• 1999

This paper empirically investigates the impact of winning a quality award by investigating the rate of return of a firm's stock in the stock market, and by analyzing the contribution and effectiveness to a firm's competitiveness. It also compares the effect of firms winning MB(Malcolm Baldrige) award with that of firms winning Korean quality awards on the stock market. A comparative method is used to analyze the change of award-winning firms'rate of return and then they are classified by time-series, cross-sectional, firm's size, award agency, and the year of receiving the award. The number of firms employed in this study is 74, however, multiple award-winning firms are included in the analysis, which increased the sample size to 118. Results indicate that Korean quality awards improve an award-winning firms'market value but not as much as the MB award did.

• Journal of Korean Society for Quality Management
• /
• v.27 no.3
• /
• pp.40-50
• /
• 1999

This paper empirically investigates the impact of winning a quality award by investigating the rate of return of a firm's stock in the stock market, and by analyzing the contribution and effectiveness to a firm's competitiveness. It also compares the effect of firms winning MB(Malcolm Baldrige) award with that of firms winning Korean quality awards on the stock market. A comparative method is used to analyze the change of award-winning firms'rate of return and then they are classified by time-series, cross-sectional, firm's size, award agency, and the year of receiving the award. The number of firms employed in this study is 74, however, multiple award-winning firms are included in the analysis, which increased the sample size to 118. Results indicate that Korean quality awards improve an award-winning firms'market value but not as much as the MB award did.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.5
• /
• pp.616-621
• /
• 2010

New type of the base material of the light-emitting diode requires copper wafer in view of heat and electrical conductance. Therefore, polishing process of the substrate level is needed to get a nanometer level of surface roughness as compared with pattern structure of nano-size in the semiconductor industry. In this paper, a series of lapping and polishing technique is shown for the rough and deflected copper substrate of thickness 3mm. Lapping by sand papers tried air cooling method. And two steps of polishing used the diamond abrasives and the $Al_2O_3$ slurry of size 100mm considering the residual scratch. White-light interferometer proved successfully a mirror-like surface roughness of Ra 6nm on the area of $0.56mm{\times}0.42mm$.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.6
• /
• pp.1003-1009
• /
• 2013

This paper presents a simple procedure to obtain the instantaneous cutting force constants needed to predict milling forces. Cutting force data measured in a series of slot milling tests were used to determine the cutting force constants at different feed rates. The values of the cutting force constants were determined directly at the tool rotation angle that maximized the uncut chip thickness. Then, the instantaneous cutting force constant was obtained as a function of the instantaneous uncut chip thickness. This approach can greatly enhance the accuracy of the mechanistic cutting force model for end milling. In addition, the influences of several cutting parameters on the cutting forces, such as the tool helix angle and axial depth of cut, were discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1994.10a
• /
• pp.33-43
• /
• 1994

A series of tensile tests have been performed to investigate the hardening behavior of rolled steel sheets. Tensile tests consist of three stages. At the 1st stage, full size tensile specimens were prestrained in the direction of rolling, then mid-sized tensile specimens were cut from the gauge sections of the full size specimens at angles to the rolling direction. At the 2nd stage, mid-sized specimens were prestrained by predetermined magnitudes of strains and miniature tensile specimens were prepared from each of the mid-sized specimens at every 10 degrees. At the final stage, from tests on miniature tensile specimens the hardening behavior of the prestrained sheets has been investigated. According to the experimental results, orthotropic symmetry is reserved during tensile elongation, and one of the orthotropy axes is continuously rotated to specimen axis. Existing theories seem to fail to explain the rotation of orthotropy axis. A new phenomenological model is proposed to explain the strain induced rotation of orthotropy axes.

• Structural Engineering and Mechanics
• /
• v.24 no.5
• /
• pp.585-599
• /
• 2006

This paper describes a series of laboratory tests carried out to evaluate the influence of bed joint orientation on interlocking grouted stabilised mud-flyash brick masonry under uniaxial cyclic compressive loading. Five cases of loading at $0^{\circ}$, $22.5^{\circ}$, $45^{\circ}$, $67.5^{\circ}$ and $90^{\circ}$ with the bed joints were considered. The brick units and masonry system developed by Prof. S.N. Sinha were used in present investigation. Eighteen specimens of size $500mm{\times}100mm{\times}700mm$ and twenty seven specimens of size $500mm{\times}100mm{\times}500mm$ were tested. The envelope stress-strain curve, common point curve and stability point curve were established for all five cases of loading with respect to bed joints. A general analytical expression is proposed for these curves which fit reasonably well with the experimental data. Also, the stability point curve has been used to define the permissible stress level in the brick masonry.

• Journal of the Korean Society of Safety
• /
• v.31 no.4
• /
• pp.143-149
• /
• 2016

In this study, a series of numerical simulation of dam break flow was conducted using EFDC model, and input conditions including cell size, time step, and turbulent eddy viscosity were considered to analyze parameter sensitivity. In case of coarse mesh layout, the propagated length of the shock wave front was ${\Delta}_x$ longer than that of other mesh layouts, and the velocity results showed jagged edge, which can be cured by applying fine grid mesh. Turbulent eddy viscosity influenced magnitude of the maximum velocity passing through gate up to 20% and the cell Peclet number less than 2.0 ensured no numerical oscillations.