• Journal of environmental and Sanitary engineering
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• v.20 no.1 s.55
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• pp.40-54
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• 2005

This dissertation aims to develop adsorption tubes for measuring organic solvents in the working environment, by comparing and analyzing breakthrough condition and adsorption capacity with ACF. 1. In breakthrough characteristics, the raising velocity of breakthrough curve is increasing according to assault concentration, but $50\%$ breakthrough time is decreasing. As breakthrough curve of calculated data using this agrees with the one of experimental data both of them can be used on determining sampling time of adsorption tubes. It is predicted by theoretical that $10\%$ breakthrough time is increasing in the case of increasing filled adsorbent amount. 2. $10\%$ breakthrough time is regularly decreasing as much as assault concentration is increasing. As a result, we can predict the life of adsorbent within the range of the low concentration, and adsorption amount that ACF can sample during $10\%$ breakthrough time is increasing as much as assault concentration is increasing.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.4
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• pp.75-81
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• 2002

In this study, experiments were carried out to investigate the characteristics of grinding and wear process of diamond wheel during grinding ceramic materials. Normal component of grinding resistance was decreasing while increase of spindle speed. The resistance of vitrified bond wheel was less then that of resinoid bond wheel because of imbedded large holes on the surface of cutting edge. Surface roughness was decreasing while increase of spindle speed. The surface roughness using vitrified bond wheel was less than that of resinoid bond wheel because of small elastic deformation. After continuous finding of ceramics, cutting edge ratio of resinoid bond wheel decreased. For the case of vitrified bond wheel, cutting edge ratio did not change.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.344-348
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• 2001

In this study, experiments were carried out to investigate the characteristics of grinding and wear process of diamond wheel grinding ceramic materials. Normal component of grinding resistance was decreasing while increase of spindle speed. The resistance of vitrified bond wheel was less then that of resinoid bond wheel because of imbedded large holes on the surface of cutting edge. Surface roughness was decreasing while increase of spindle speed. The surface roughness after using vitrified bond wheel was less than that of resinoid bond wheel because of small elastic deformation. After continuous grinding of ceramics, cutting edge ratio of resinoid bond wheel decreases. For the case of vitrified bond wheel, cutting edge ratio does not change.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.3
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• pp.33-44
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• 1983

This paper deals with the experimental study on the behavior of fuel (methanol) in intake manifold by using the basic apparatus which is manufactured the visible straight tube type model. In this study, the new device for liquid film thickness measurement and vaporization rate measurement are introduced to investigate the variation of liquid film thickness along the intake manifold and to observe the effect of vaporization of injected fuel. the results are summarized as follows: 1) The vaporization rate increases in proportion to decreasing of throttle valve angle and growing air fuel ratio. 2) The liquid film thickness along the intake manifold is mostly independent for the throttle valve angle in low air velocity and then affected in high air velocity, but the distribution of the liquid film thickness on circumferential position almost constant in the region of 300mm down stream from carburetor. 3) The mean liquid film thickness is 0.04 - 0.18mm in case of methanol in the region of air velocity Va = 12m/s - 55m/s and decreases with decreasing the throttle valve angle.

• Journal of the Korean Society of Combustion
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• v.1 no.1
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• pp.41-49
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• 1996

Effects of ambient geometry on the liftoff characteristics are experimentally studied for nonpremixed turbulent jet flames. To clarify the inconsistency of the nozzle diameter effect on the liftoff height, the ambiences of finite and infinite domains are studied. For nonpremixed turbulent jet issuing from a straight nozzle to infinite domain, flame liftoff height increases linearly with nozzle exit mean velocity and is independent of nozzle diameter. With the circular plate installed on the upstream of nozzle exit, flame liftoff height is lower with plate at jet exit than without, but flame liftoff characteristics are similar to the case of infinite domain. For the confined jet having axisymmetric wall boundary, the ratio of the liftoff height and nozzle diameter is proportional to the nozzle exit mean velocity demonstrating the effect of the nozzle diameter on the liftoff height. The liftoff height increases with decreasing outer axisymmetric wall diameter. At blowout conditions, the blowout velocity decreases with decreasing outer axisymmetric wall diameter and liftoff heights at blowout are approximately 50 times of nozzle diameter.

• 한국전산유체공학회:학술대회논문집
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• 1995.10a
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• pp.241-245
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• 1995

This paper presents the studies on the variation of shape and thickness of a normal shock wave with Mach number and density by using the most useful numerical technique in rarefied gas regime, DSMC(Direct Simulation Monte Carlo). Calculations are peformed for the three different Mach numbers and for one Mach number with different densities. From the obtained results, we find that the shock thickness is decreasing with increasing Mach number, and there are much variations in thickness and shape with decreasing density. Also, there is a noticeable overshoot of the translational temperature near the shock center in the case of a large Mach number.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.86-91
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• 2007

This study was investigated to know the effect of subzero treatment in austempered ductile cast iron. Retained austenite transformed to martensite by subzero treatment. With decreasing subzero treatment temperature, more volume fraction of retained austenite transformed to martensite and transformed to martensite above 30% by subzero treatment temperature at $-196^{\circ}C$. With decreasing subzero treatment temperature, the value of strength and hardness increased but the value of elongation and impact value decreased. In case of subzero treatment at $-196^{\circ}C$, hardness value increased about 18% and impact value decreased by above 20%. We could find that subzero treated specimens had a little of effect on the tensile properties but had very much effect on the hardness and value of the impact.

• YAKHAK HOEJI
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• v.22 no.4
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• pp.193-200
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• 1978

Cholic, ursodesoxycholic, chenodesoxycholic, desoxycholic and hydesoxycholic acids were dissolved in the propylene glycol to make solution and then above solution of cholanic acids on bile secretion was investigated by injection those solutions into small intestine of rabbits and albino rats. The cholates in bile juice from rabbits injected with cholic acid were remarkably increased and therefore it exhibited a typical choleretic action. In view of pharmacological point, desoxycholic acid is considered as superior hydrocholeretic agent, and ursodesoxycholic and chenodesoxycholic acids have similar effect in decreasing order. However, the effect of bile secretion by hyodesoxycholic acid was almost negligible as that by propylene glycol administered. The cholate content in the bile juice from albino rat was increased by cholic and desoxycholic acids in decreasing order: i.e., they exhibited choleretic action. In the case of ursodesoxycholic and chenodesoxycholic acids, the concentration of cholate was slightly increased in bile juice from the rat, so that these cholates showed a weak choleretic action. While total output of bilirubin was increased by chenodesoxycholic acid, the other cholanic acid showed no effect in the rabbit.

• Korean Journal of Microbiology
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• v.16 no.3
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• pp.103-110
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• 1978

Saccharomyces cerevisiae strain M. was cultured in a molasses-containing media with different amounts of phosphorous and nitrogen sources. The effects of constituents of the cell on the functional activity as well as sensitivity of it were investigated, the results obtained being summarised as follows : Both the thermotolerance and dry tolerance of the yeast cell were higher when the more carbohydrate and thehalose were present in the yeast cell. During the drying, the rate of dead cell was noted increasing and the fermentability decreasing, but it was more remarkable at early stage of the decreasing rate of drying, and at the same time increasing rate of dead cell and decrease of fermentability were more remarkable in the yeast cell containing much protein. In this case the speed of drying was slower. The trehalose content in the yeast cell increased during early stage of the drying and this increase was higher when content of trehalose and carbohydrate in the initial yeast cell was relatively high.

• Journal of Ocean Engineering and Technology
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• v.5 no.1
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• pp.71-80
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• 1991

This paper reveals the effect of the effective case depth(ECD) on the fatigue behavior of a high-frequency induction hardened SM45C in rotated bending fatigue test. In addition, the effects of fracture modes(surface origin type, inner origin type) on it are discussed. The fatigue limit of the induction hardened steel is remarkably increased compared with that of base metal. In addition, the fatigue limit is linearly increased as the effective casedepth grows deep in the region of this experiment (ECD/R;0.23-0.49). The S-N curve and fracture mode in the induction case hardened steel are classified into two kinds, as a result : N$_{f}$<10$^{5}$ ;surface origin type fracture(at high stress), N$_{f}$>10$^{5}$ ; in ner origin type fracture(at low stress). In case of inner origin type fracture; as the effective case depth(ECD) gets deep, the fatigue limit is increased by the reason that the fracture origin moves toward center; in reverse, is decreased by reason that the compressive residual stress gets low. As a result, the increasing effect of the former is much bigger than the decreasing effect of the latter, and the fatigue limit is increased as the ECD gets deep.eep.