• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.74-79
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• 2004

The shape of cold rolled steel sheets is the degree of flatness, and the flatter, the better. Because undesirable strip shapes of cold rolled steel sheets can affect not only visible problem but also automatic working process in customer's lines, the requirement of the customers is more and more stringent. So we usually used the tension leveler to make high quality of strip flatness. For the improvement of the quality of strip flatness, this report developed three-dimensional FEM (Finite Element Method) simulation model, and analysis about the strain and stress distribution of strip in the tension leveling process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.08a
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• pp.261-267
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• 2004

Current steel makers are trying to develop new manufacturing process to secure price competition and to improve productivity by testing a various kinds of rolling condition of several kinds of steel at TCM. Accordingly, Reverse Mill operation for Stainless steel is changing to TCM operation and furthermore, even general carbon steel and electric steel plate are requested to be worked at TCM simultaneously. By these changing of rolling condition, it become to be necessary to develop new water-soluble cold rolling oil that has a characteristics to be suitable for various working condition and in this report, we would like to mention lubrication condition to fulfill requested characteristics of each steels and development and applying result of multi-purpose water-soluble cold rolling oil which has such an lubrication property.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.473-477
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• 2000

The experimental study of die-sinking electrical discharge machining(EDM) was conducted for Cold Die Alloy Steel of SKD-11 with rotary electrode according to the peak current of 11A, 15A and 19A, and the duty factor of 0.24, 0.45. dielectric fluid flow through the electrode inside according to the change of electrode internal diameter during the EDM working. Material removal rate(MRR) was increased with flushing & rotation of electrode at the condition for the peak current of 15A, 19a but the MRR is decreased at the flushing only. The more surface roughness was obtained for the case of the flushing & rotation under the peak current of 19A.

• International Journal of Advanced Culture Technology
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• v.3 no.2
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• pp.124-131
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• 2015

Computational fluid dynamics (CFD) has been employed for the Heat exchanger efficiency of a counter flow heat exchanger. The Heat exchanger efficiency has been assessed by considering the computed Nusselt number and flow friction characteristics in the double pipes heat exchanger equipped with two types twisted-tapes: (1) single clockwise direction and (2) alternate clockwise and counterclockwise direction. Cold and hot water are used as working fluids in shell and tube side, respectively. Hot and cold water inlet mass flow rates ranging are between 0.04 and 0.25 kg/s, and 0.166 kg/s, respectively. The inlet hot and cold water temperatures are 54 and $30^{\circ}C$, respectively. The results obtained from the tube with twisted-tapes insert are compared with plain tube. Nusselt number and friction factor obtained by CFD simulations were compared with correlations available in the literature. The numerical results were found in good agreement with the results reported in literature.

• Journal of Chest Surgery
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• v.17 no.4
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• pp.574-586
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• 1984

Although corticosteroid have been shown to stabilize lysosomal membranes and prevent release of hydrolytic enzymes, the mechanism of membrane stabilization remains obscure. This study described functional assessment of efficiency of methylprednisolone in GIK solution by using a isolated Rat Heart Model. Isolated rat heart were subjected to a 2-minute period of coronary infusion with a cold GIK or methylprednisolone mixed cold GIK solution immediately before and also at the midpoint of a 60-minute period of hypothermic [$10{\pm}1^{\circ}C$] ischemic arrest. The result of this were as follow: 1.Spontaneous heart beat after ischemic arrest occurred 11 second later after Langendorffs reperfusion in the methylprednisolone mixed GIK group and 14 second later in the control group. 2.The percentage of recoveries of heart rate at 30 minute after postischemic working heart perfusion was 88.6\ulcorner.6% in the methylprednisolone mixed GIK group. This percentage of recovery was not significantly greater than the control group. 3.The percentage of heart function at 30 minute after postischemic working heart perfusion were; peak aortic pressure $90.8{\pm}4.5%$ coronary flow $87.5{\pm}1.45$ and aortic flow $74.9{\pm}11.8%$ in the methylprednisolone mixed GIK group. This percentage of recovery was significantly greater than the control group. [p<0.05]

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.448-453
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• 2005

Temperature Control Valve (TCV) is one of the useful temperature control devices, which is used to control constant temperature of working fluid in power and chemical plants and domestic water supply systems. TCV is composed of body, cylinder and piston, and the body shape has a symmetrical H-type. In general, it has several inlet and outlet holes, and its shape is like as tubular sleeve. The piston has three rings two rings of the end of piston have the function of controlling inlet flow rate with hot and cold working fluids, the center ring has the function of preventing hot and cold water from intermixing. Consequently, the shapes of piston and cylinder are the main design parameters in the performance of TCV. In this study, numerical analyses were carried out with two different piston and cylinder shapes to investigate the functions as a temperature control valve and the flow characteristics according to piston opening grade in TCV. Using a commercial code, FLUENT, velocity and pressure fields in TCV are obtained under steady, standard $k -{\epsilon}$ turbulence model and no-slip condition.

• Tribology and Lubricants
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• v.20 no.3
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• pp.145-151
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• 2004

A modified surface layer by ion implantation is very thin (under 1 $\mu\textrm{m}$) but has superior mechanical characteristics. therefore ion implantation has been used successfully as a surface treatment technology to improve the wear, fatigue, and corrosion resistances of materials. MEVVA which is a kind of ion beam apparatus has merits of low cost and is usable to various metals, but occurs a droplet ranging from micron to tens of micron on the implanted surface at ion implantations. wear is a dynamic phenomenon on interacting surfaces with rotative motion. Since wear changes in condition of the surface, we should control to surface. In order to improve a wear resistance of Ti ion implanted 1C-3Cr steel(material for roller in the cold working process), it is essential to investigate the effect of the droplets on the wear characteristics. In this study, we investigate the effect of the droplets on the wear characteristics of 1C-3Cr steel using SEM Tribosystem as in-situ system. Results show that the droplet occurred at ion implantation becomes the cause of severe wear. Therefore, the ion-implanted surface should be removed the droplet to improve wear resistance.

• New & Renewable Energy
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• v.18 no.2
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• pp.82-89
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• 2022

In this study, the exergy characteristics were analyzed, according to the mass flow rate of the propane working fluid and the pressure change in the turbine inlet, for the efficient recovery of cold energy and exhaust heat by the waste energy recovery system applied to the LNG FSRU regasification process. When the turbine inlet pressure and mass flow rate of the Primary Rankine Cycle were kept constant, the exergy efficiency and the net power increased. This occurred as the turbine inlet pressure and the mass flow rate of the working fluid increased in the Secondary Rankine Cycle, respectively, and the maximum values were confirmed. In this regard, the fluctuations in the exergy rate flowing into and out of the system and the exergy rate destroyed by pumps, evaporators, turbines, and LNG heat exchangers (condensers) were examined in detail.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.107-118
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• 2002

This paper deals with an automated computer-aided process planning and die design system by which designer can determine operation sequences even if they have a little experience in process planning and die design of quasi-axisymmetric cold forging product by cold former working. The approach to the system is based on knowledge-based rules and a process knowledge base consisting of design rules is built. Knowledge for the system is formulated from plasticity theories, empirical results and the empirical knowledge of field experts. Programs for the system have been written in AutoLISP for the AutoCAD using a personal computer. An attempt is made to link programs incorporating a number of expert design rules with the process variables obtained by commercial FEM softwares, DEFORM and ANSYS, to form a useful package. The system is composed of three main modules and five sub-modules. The process planning and die design module considers several factors, such as the complexities of preform geometry, punch and die profiles, specifications of available cold farmer, and the availability of standard parts. As the system using 2D geometry recognition is integrated with the technology of process planning, die design, and CAE analysis, the standardization of die parts for wheel bolt requiring cold forging process is possible. The developed system makes it possible to design and manufacture quasi-axisymmetric cold forging product more efficiently.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1059-1064
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• 2012

In this study, tensile tests were performed on specimens that simulated the cold-bending and heat-treatment of pipe bends to understand the mechanical properties of pipe bends manufactured by cold-bending followed by heat-treatment for relieving residual stress. The strength and ductility of cold-worked materials were respectively found to be higher and lower than those of the parent material although heat-treatment was carried out to relieve residual stress. In addition, the increase in strength and decrease in ductility were proportional to the applied strain levels for cold-working. It was thus inferred that the intrados and extrados regions of pipe bends that were cold-bended and heat-treated show higher strength and lower ductility compared to the parent straight pipe and that the mechanical properties at the crown region are nearly the same as those of the parent straight pipe.