• Journal of the Korean Society of Safety
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• v.23 no.6
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• pp.131-137
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• 2008

SCP(Sand Compaction Pile) method that forms a composite ground by driving compacted sand piles into the soft ground. This method is one of the soil improvement techniques for reinforcing and strengthening soft ground deposits. This thesis describes the investigation on the behavior of soft ground reinforced with SCP by low improvement ratio. Direct shear test and consolidation test carried out to verified behavior of composite ground reinforced with SCP. Test results were discussed with reference to the amount of consolidation settlement, variation of shear resistance with area replacement ratio and effect of the stress concentration. And, laboratory model loading test carried out to verified the effect of the location and failure mode of reinforced embankment. Residual shear strength varies with the area replacement and constrict load in the low replacement ratio. Calculated stress concentration ratio overestimate than proposed valve by experimental, theoretical and analytical method. As regards the location, improving right below of the top of the slope was more effective than below of the toe of the slope. This thesis carried out to obtain fundamental information of behavior of the composit ground. Hereafter, centrifuge test that reproduce stress state of the in-situ must be necessary through the further study about pile penetration, reinforce position and construct time.

• Journal of Korea Water Resources Association
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• v.55 no.spc1
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• pp.1251-1260
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• 2022

Recently, due to the deterioration of watermains and the detachment of scale which is accumulated on the watermain surface, water quality accidents in a water supply network occur frequently. As scale accumulated on watermains is stabilized, it may not cause water quality accidents under the normal operating condition. However, due to water hammer or transient flow caused by the abrupt velocity and/or direction of flow change, it can be detached from the watermain surface resulting in water quality accidents. To prevent these kinds of water quality accidents, it is required to remove scale by watermain cleaning regularly. Many researches about flushing which is the most popular water cleaning method are focused on the desirable velocity criteria and the cleaning condition to accomplish the effect of flushing whereas less amount of research effort is given to develop a method to consider whether the desirable velocity for flushing can be obtained before flushing is performed. During flushing, the major and minor headloss is occurred when flushing water flows through a hydrant or drain valve. These headloss may slow down the velocity of flushing water so that it can reduce the flushing effect. Thus, in this study, we suggest a method to simulate the flow velocity of flushing water using "MinorLoss Coefficient" and "Emitter Coefficient" in EPANET. The suggested method is applied to a sample network and the water supply network of "A" city in Korea to compare the flushing effect between "flushing through a hydrant" and "flushing through a drain valve". In case of "flushing through a hydrant", if the hydraulic condition ocurring from a watermain pipe connecting to the inlet pipe of a hydrant to the outlet of a hydrant is not considered, the actual flowrate and velocity of a flow is less than the simulated flowrate and velocity of a flow. In case of "flushing through a drain valve", the flushing velocity and flowrate can be easily simulated and the difference between the simulated and the actual velocity and flowrate is not significant. Also, "flushing through a drain valve" is very effective to flushing a long-length pipe section because of its efficiency to obtain the flushing velocity. However, the number and location of a drain valve is limited compared to a hydrant so that "flushing through a drain valve" has a limited application in the field. For this reason, the engineer should consider various field conditions to come up with a proper flushing plan.

• Journal of the Korean Institute of Gas
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• v.16 no.4
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• pp.38-43
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• 2012

The purpose of this study is to carry out the consequence analysis of an accident related to the release of Hydrogen chloride occurred in a petrochemical company in Korea and suggest the measures to prevent similar accidents from happening again. The total amount released through the safety valve of HCl Column was calculated based on the rated capacity of the safety valve, the ideal gas equation and mechanical energy balance, respectively. As a result of the calculation, we found that the amount of HCl released through the safety valve was at least 76.8 kg. Also, we predicted the dispersion concentration at the position of the injured workers(more than 350 m away from the accident location) using simulation programs such as PHAST. The results of ALOHA and K-CARM are 304 ppm and 1,700 ppm respectively. However, PHAST calculation indicated that the concentration is less than l ppm. From these results, we can understand that workers were injured by HCl gas released from the safe valve and the concentration of gas might be less than 1 ppm. Also, it is important for toxic gases such as HCl to be vented safely to the atmosphere after scrubbing.

• Journal of Chest Surgery
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• v.31 no.9
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• pp.855-860
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• 1998

Background: Adequate exposure of the mitral valve is a prerequisite for mitral procedures including the repair. An extended transseptal approach in mitral valvular operations is known to have certain technical advantages in recent years because of the anatomic posterior location of the mitral valve, especially in reoperations and in the presence of the small atrium in spite of the possibility of arrhythmia due to injury of sinus nodal artery. Material and Method: We compared the preoperative status, operative, and postoperative factors among patients in two study groups, transseptal only (Group I, n=10) and extended transseptal approach(Group II, n=25). Result: There were no differences in age, sex, NYHA functional class, left atrial size, and left ventricular function. The incidence of the redo-operation was high and early postoperative arrhythmia, which was improved later, appeared in 3 patients in Group II, but not in Group I. Conclusion: We believe that atrial septal incision could be extended up to the atrial roof whenever exposure of the mitral valve during a transseptal approach is inadequate because the late results were similar.

• Journal of Mechanical Science and Technology
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• v.20 no.3
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• pp.345-357
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• 2006

By employing the concept of equivalent linkage, this paper presents an analytical method for analyzing the mechanical errors of disk cam mechanisms with a flat-faced follower. The resulting error equations do not really involve the location of the curvature center of the cam profile, and locating the curvature center of the cam profile is not essential. The resulting errors are significantly affected by the pressure angle, and the smaller pressure angle will result in the smaller mechanical error. In the worst case, owing to the joined effects of various design parameters, the accuracy of the follower motion may degrade considerably. For the oscillating follower case, all acceleration error functions have a sudden change at every beginning and at every end of the motion even though the theoretical follower displacement is cycloidal motion.

• Journal of Power System Engineering
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• v.7 no.3
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• pp.23-28
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• 2003

In heavy nuclear power plant, high energy through main steam line is provided to turbine that generate the electric power. Since plant had generated power, high noise has been occurred. Noise make equipments and work environment worse. For finding out the location and the cause of making noise, noise was measured along main steam line at open/close test of Main Steam Isolation Valve (MSIV hereafter). As the result, it was identified that the vortex shedding in the cavity of MSIV is main noise source. The profile change of MSIV seat ring was proposed as the method of noise reduction. After filletting MSIV seat ring, the noise level reduced $10{\sim}20dB$ compared before the change of profile.

• Journal of Chest Surgery
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• v.37 no.1
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• pp.76-79
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• 2004

The remote location of VSD relative to the aortic valve imposes considerable surgical difficulties in the repair of DORV with noncommitted VSD. We report a successful biventricular repair of the anomaly with VSD rerouting to pulmonary artery followed by arterial switching operation.

• Journal of the korean Society of Automotive Engineers
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• v.6 no.2
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• pp.64-75
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• 1984

In the engine design, it will be able to higher compression ratio and decreasing the cylinder size, if improve the vaporization of fuel and increasing the mass burned fraction in the kerosene engine. Therefore, concave, convex and straight types of hear ring set up neighborhood intake valve into the combustion chamber. The vaporization effect of fuel satisfied by heat transfer from the heat ring, but have need of selection of the location and surface area of the heat ring. Also, combustion duration of the combustion chamber with concave heat ring shorter than combustion chamber with other two types of heat ring, and about 30percent decreases in combustion duration as compared with combustion chamber without heat ring.

• Journal of the korean Society of Automotive Engineers
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• v.9 no.3
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• pp.85-93
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• 1987

The intake system of 4-cycle, 4-cylinder reciprocating engine is investigated the simple model composed of vessel, duct and throttling part. The numerical calculation based on the simulation is performed for the flow phenomena including heat transfer, friction and bend of duct at each part. In the multi-cylinder engine, the volumetric efficiency is increased a little as the junction location is closed to cylinder at the engine speed having maximum volumetric efficiency. The configuration and dimension of intake system have an influence on the inertia effect by resistance and pressure variation, and the magnitude of that is varied by the engine speed. Thus the volumetric efficiency is correlative to them. The volumetric efficiency is high as the intake valve close is advanced at the low engine speed, and is delayed at high speed.

• Journal of Veterinary Clinics
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• v.19 no.1
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• pp.110-113
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• 2002

An atrial septal defect (ASD) is a congenital hole in the atrial septum that allows flow between the two atria. Small ASDs are usually well-tolerated defects and do not result in significant clinical abnormalities. In large ASDs or in the presence of other cardiac defects, clinically significancy is increased. Atrial septal defects in 2 Dogs with cardiac and respiratory signs were diagnosed at seoul animal medical center. In ascultation, systolic murmur and the splitting of second heart sound were heard at pulmonary or tricuspid valve region. In radiograph, right-sided cardiomegaly, pulmonary artery dilation, increased pulmonary vasculature makings, and pleural effusion or pulmonary edema signs were observed. In echocardiography, the region, location and size of septal defect was identified. Also, the direction and degree of shunt was measured. These dogs were treated with medicine for cardiac failure. One dog is well-tolerated, the other dog died.