• Computers and Concrete
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• v.17 no.4
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• pp.435-453
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• 2016

The main purpose of this study is to perform optimum cost design of cut and cover RC shallow tunnels using Artificial bee colony and genetic algorithms. For this purpose, mathematical expressions of objective function, design variables and constraints for the design of cut and cover RC shallow tunnels were determined. By using these expressions, optimum cost design of the Trabzon Kalekapisi junction underpass tunnel was carried out by using the cited algorithms. The results obtained from the algorithms were compared with the results obtained from traditional design and remarkable saving from the cost of the tunnel was achieved.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.777-780
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• 2005

The bench of cut-slope is necessary to stabilizing. But it is possible to be a weak zone in slope. When a small scale failure is occurred in a bench, it influence a large scale failure of slope. So when it is found out any unstable factor, weathering of rock, a direction of joint in a bench, if the bench is reinforced suitably, the holly failure is prevented in cut-slope

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.419-424
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• 2001

TCV(Temperature control valve by pressure compensation) controls temperature constantly, when it is sending steam or high temperature water to heating device of heat exchanger. For designing TCV, the ratio of piston and hole diameters is one of the important design parameters. Numerical analysis is carried out to elucidate the flow characteristics in the TCV with different port areas of cold and hot waters, using the k-$\epsilon$ turbulence model and Cartesian cut-cell method. Numerical results show that the exit flow rate is mainly affected by pressure distribution in the piston.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.33-38
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• 2012

An experimental study was carried out to observe the characteristics of impingement of assist gas from a rectangular supersonic nozzle on kerf surface in laser machining. A micro-scale supersonic (Mach number 2.0) rectangular nozzle system was designed and fabricated for the purposes, and hot tests of the performance of the nozzle system was proceeded in the ITI corporation laboratory. For various related parameters such as laser powers, nozzle pressures and cutting speeds, the quality of the frontal view of cut edge surfaces was observed by a microscope. In the study, it was shown that the application of the present micro-rectangular supersonic nozzle in an off-axis configuration made it possible to cut a mild steel, by combinations of relatively low laser - powers, large standoff distances, and assist gas with no oxygen, which was not achieved by conventional laser cutting processes.

• Journal of the Korea Society for Simulation
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• v.14 no.4
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• pp.1-8
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• 2005

In a metal grating manufacturing process, the cutting operation allocates the gratings and cut them out from given panels or a plate sheets. Before the cutting operation an operator generates a cutting plan. The cutting plan should decide how pieces of metal rectangles i.e., gratings, are allocated and cut from the panel. This plan generation is a deal of weight on the production cost. the generation of cutting plan is similar to the general two-dimensional cutting problem. In this paper, we first define cutting problem and Af algorithm of Artificial Intelligence to solve the problem. Also, through a simulation, we compare the proposed cutting algorithm to an existing method in terms of material loss

• Journal of the Korean Society for Precision Engineering
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• v.17 no.5
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• pp.131-136
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• 2000

This paper is concerned with the surface roughness and the bending strength of ground workpiece in ZrO2 ceramic grinding. Surface roughness was measured with surface tracer and bending strength value was obtained by three-point bending test on machining center using tool dynamometer. Grinding experiments were carried out to examine the effects of grinding conditions including diamond mesh size, table speed, and depth of cut on ground surface roughness. The correlation between surface roughness and bending strength was also inspected. The experimental results indicate that the rougher surface is produced as the mesh size of diamond wheel is reduced and table speed is increased, but surface roughness is not affected by depth of cut. The values of bending strength decrease as the values of Ra, Rmax and Ku increase.

• Journal of the Korean Society of Tobacco Science
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• v.21 no.2
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• pp.144-151
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• 1999

This study was carried out to compare the change physico-chemical properties in the 10 grades of Burley leaf tobacco expanded by $CO_2$. The filling capacity of AB3T was increased from 5.44cc/g to 9.52cc/g with the expansion rate 75.0% and that of CD3W was increased from 5.57cc/g to 10.16cc/g with the expansion rate 82.4%. But the rate of cut tobacco longer than 3.36 mm decreased from 77.2% to 49.9% and from 67.3% to 41.2% in grade B1T and C1W, respectively. The contents of nicotine and total volatile base in the of expanded cut tobacco decreased 11.9% and 10.4% respectively. The contents of onganic acids, except oxalic and palmitic acid, essential oil, amino acids, nicotine, tar and ammonia contents in the cigarette smoke decreased by expansion procecs. These results suggest that expanded tobacco was very useful to make less irritative cigarettes.

• Journal of the Korean Ceramic Society
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• v.37 no.2
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• pp.140-144
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• 2000

Laser cutting of thick diamond films is studied using a low-power(10 W) copper vapor laser. Due to the existence of the saturation depth in laser cutting, thick diamond films are not easily cut by low-power lasers. In this study, we have adopted a low thermalconductivity underlayer of alumina and a heating stage (up to 500$^{\circ}C$ in air) to prevent the laser energy from consuming-out and, in turn, enhance the cutting efficiency. Aspect ratio increases twice fromm 3.5 to 7 when the alumina underlayer used. Adopting a heating stage also increases aspect ratio and more than 10 is obtained at higher temperatures than 400$^{\circ}C$. These results show that thick diamond films can be cut, with low-power lasers, simply by modifying the thermal property of underlayer.

• International Journal of Safety
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• v.9 no.1
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• pp.12-20
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• 2010

In this study, a series of random field test and dynamic analysis in the time domain were carried out in order to find in the reason of fatigue damage of the main and the secondary members in the 3-span continuous steel plate girder railway bridge being under in service over 60 years. From the measured and the analyzed results, the stress distribution patterns were investigated for the members with fatigue damage. In addition, global and local numerical stress analysis was performed for the members damaged severely by corrosion, to estimate variation of the distribution by corrosion. Finally, a reasonable cut-off ratio in the steel plate railway bridge will be proposed by analyzing the equivalent stress ranges according the ratio.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.465-470
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• 2000

This paper is concerned with the surface roughness and the bending strength of ground workpiece in ZrO2 ceramic grinding. Surface roughness was measured with surface tracer and bending strength value was obtained by three-point bending test on machining center using tool dynamometer. Grinding experiments were carried out to examine the effects of grinding conditions including diamond mesh size, table speed, and depth of cut on ground surface roughness. The correlation between surface roughness and bending strength was also inspected. The experimental results indicate that the rougher surface was produced as the mesh size of diamond wheel is reduced and table speed is increased, but surface roughness is not affected by depth of cut. The values of bending strength decrease as the values of Ra, Rmax and Ku increase.