• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.125-131
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• 2005

The purpose of the present study is to examine the flow characteristics of ER fluids between 2 port and 3 port rectangular tube brass electrodes. ER fluid is made silicon oil mixed with $2-3wt\%$ starch having hydrous particles. Flow visualization of the ER fluids were obtained by CCD camera measuring those of the clusters using an image processing technique. This research found the flow $rate(Q_L)$ with 0 kV /mm, 0.5kV/mm and 1.0kV/mm for $Q_L\;=\;0,\;0$ and $5.73cm^3/s$. When the strength of the electric field increased, the cluster of ER fluids are clearly strong along the rectangular tube and the flow rate(Q) decreased.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.87-92
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• 1999

This paper was undertaken to do morphological analysis of wear particles for sliding members hydraulic rotary actuator. The lubricating wear test was performed under different experimental conditions using the wear test device and wear specimens of the pin on disk type was rubbed in paraffinic base oil by three kinds of lubricating materials, varying applied load, sliding distance. The four-shape parameters (50% volumetric diameter, aspect, roundness and reflectivity) are used for morphological analysis of wear particles. The results showed that the four shape parameters of wear particles depend on a kind of the lubricating materials. It was capable of presuming wear volume for three kinds of materials on driving time.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.126-132
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• 2008

The vibration and disturbances from operating the compact disk layer have an effect on the play ability. As the excitation sources of the compact disk player, there are the vibration of the motors and gears, impact by mechanical parts and the external excitations. So, most of the compact disk player have a anti-vibrational system, which is included some rubber or oil dampers. In this study, the vibration characteristics of rubber damper which is used home compact disk player are investigated. The materials and shape of rubber damper are changed, and the transmissibility is measured. As a conclusion, the natural frequency is moved to higher frequency and the transmissibility is reduced by the increasing rubber stiffness. In comparison to butyl rubber damper, the transmissibility of silicon damper was increased by larger restitution elasticity. The hollow damper was effective to reduced the transmissibility.

• Bulletin of the Society of Naval Architects of Korea
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• v.9 no.2
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• pp.33-42
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• 1972

This paper was studied on the behavior, crack formation and propagation of slip bands on low carbon steel which was heat-treated in three conditions in order to change metallic structure. The specimens were tested by rotating bending fatigue testing machine and also observed the variations of grains by microscope. From the test results it was clear that fatigue endurance limit and life of low carbon steel were more increased in contrast with the case that the grain size of specimen was more decreased. Slip bands developed at oil-quenched specimen and furnace-cooled specimen. Formed cracks in the first one or two grains below the surface were approximately "planar" type, there after they followed "wavy" type. It was also found that cracks at 30% higher stress than fatigue limit were usually developed inter-granular, and cracks at 12% higher stress than fatigue limit were propagated meandering path, partly trans- and partly inter-grandular.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.687-689
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• 2003

Recently, issues regarding environment and the diversification of dependence in oil are watched with keen interest. Wind power attracts most interest because of its high-energy efficiency with environment friendly functions. The paper discusses the development of a coreless axial-flux permanent magnet (AFPM) generator for a wind power system. Analyzed the Coreless AFPM generator by electromagnetic, and designed wind power generator with this. The 3 phase output of stator is rectified and fed to a common do link. The overall machine structure has high compactness and lightness, because of the lack of the iron core. The test results with a resistive load confirm the satisfactory operation of generator. Compared with conventional generator, the design has lower weight, lower Power loss and improved efficiency.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.388-389
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• 2007

Objective of the study is development of 23kV insulating jackets for protection of workers from electrical shock. The breakdown voltage of Ethylene-VinylAcetate copolymers(EVA) films in insulating oil were measured. Insulating jackets were made by the high frequency welding machine, and withstanding voltage test of these were measured. For breakdown voltage at AC 30kV, the number of EVA film with $105{\pm}5{\mu}m$ thickness was 4$\sim$5pieces. When AC 30kV during 3 minutes supplied on the insulating jackets, those were keep on the good quality.

• Tribology and Lubricants
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• v.13 no.2
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• pp.39-45
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• 1997

The shot peening treatment were conducted for improving the strength of rolling contact fatigue of machine element like a gear. This paper was undertaken to analyze the influence of shot peening treatment for inner race of ball bearing on the rolling contact fatigue. Shot peening treatment were applied to the full hardened and the carbonitrided bearing. And the rolling contact fatigue life test and X-ray diffraction test were carried out. The results of this study showed that the fatigue life of ball bearing in the clean and the contaminated oil could be improved by shot peening treatment. This effect was found to be more pronounced to the full hardened bearing. These facts might be due to the generation of compressive residual stress and the strain hardening of surface layer by shot peening treatment. The failure of the shot peened bearing were presumed to initiate at surface.

• Journal of the Korean Society for Precision Engineering
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• v.7 no.2
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• pp.113-123
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• 1990

To study deleterious effects of contaminants contained in lubricating systems, the effects of fine alumina particle concentration and size on the critical failure load, friction and wear characteristic were examined on boundary lubrication condition using the four ball machine. The following conclusions are deduced: The abrasive is found to cause a transition from mild wear to severe wear at less severe conditions than with clean oil. In mild wear region the friction and wear increase with particle size and concentration, but in severe wear region do not exhibit any definite trend. In relation to film thinckness there is a threshold of particle size beyond which the failure load no longer decreases with particle size.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.49-52
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• 2000

In this paper we have developed an image security system based on Internet Web in order to overcome the problem of existing systems that use the dedicated network. The developed system resolves the safety problem of the centralized control model by adapting the distributed control model based on Web, and has the functions of remote control and automatic monitoring for grouped multiple sites on Web browser. And the system can operate various computers or operating system because it's operating software was designed by the concepts of Java Virtual Machine and Virtual Instrument. Also, our system has not need of additional cost for network construction by using Internet and can greatly improve the managemental efficiency of system because the maintenance and publishing of software updates can be performed through Web Server.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.4
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• pp.131-136
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• 2011

In commercial vehicle, sub-frame which equipped in main frame supporting dump deck and oil tanker. This is the main structure for all equipment which including joint function. Sub-frame is made by welding process, this susceptible to deform and crack by its longitudinal size. Also various kind of sub-frame make it difficult to standardization in manufacturing process and exclusive jig is not adapted yet. Frame size is over 6~8m and weight is more than 300kg this make re-work more difficult. If manufacturing company made precise sub-frame, this is not only convenient for customers but also save the company money by reducing the working time. In this study manufacture the sub-frame be suitable for its main function and develop exclusive welding jig for obtain checking fixture function as well.