• Structural Engineering and Mechanics
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• v.64 no.3
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• pp.323-328
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• 2017

This paper presents a three-dimensional finite element method analysis of repairing plate with bonded composite patch subjected to tensile load. The effect of the corrosion on the damage of the adhesive (FM73) in the length of two horizontal cracks on the both sides is presented. The obtained results show that the crack on the left side creates a very extensive area of the damaged zone and gives values of the stress intensity factor (SIF) higher than that on the right side. We can conclude that the left crack is more harmful (dangerous) than that on the right side.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.159-162
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• 2008

In this paper, a numerical simulation of three-dimensional flow field and heat transfer coefficient distribution are conducted for two types of gas turbine blade with plane and squealer tips. The numerical results show that gas turbine blade with squealer tip considerably changes the flow structures near the tip regions of pressure and suction sides, so the overall heat transfer coefficients on the tip and shroud with squealer tip are lower than those with the plane tip blade. Finally, the effect of tip gap clearance on the flow field and heat transfer characteristics are investigated.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2779-2786
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• 1994

This study presents an experimental investigation of the effect of the wake on mass transfer about a circular cylinder in crossflow. The flat-plate wake was generated by merging two mirror images of turbulent boundary layers that were well developed along the both sides of flat plate with a sharp trailing edge. The velocity field was measured by a hot-wire system and the mass transfer rate by a naphthalene sublimation method. The mixing and developing stages of the wake were addressed to identify flow conditions. The mass transfer effects of different developing stages of the wake was discussed in detail. It is noted that a local maximum appears not at the front stagnation point but at a point a little downstream when the cylinder is located in the nearwake region and much more elevated mass transfer rate is obtained compared to effect of free-stream turbulence.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.46-52
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• 2003

For position control of electro-hydraulic servo system, single rod cylinders and double rod cylinders are used. Single rod cylinders have simple structure for manufacturing but different volume ratio of two sides induce to non-linearity in process of then mathematical modeling. So only with conventional PID control method it is difficult to control single rod cylinders precisely. For mole precise position control of single rod cylinders, a controller which is inserted a velocity feedback PID controller and MRAC controller are proposed. With experiment control performances of three control methods are compared. In case of experiment, for external varying load to the system, a hydraulic cylinder and a pressure control valve are used. In conclusion a MRAC is considered a suitable control method for external varying load.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.92-97
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• 2004

The aim of this study is to estimate the strength of injection molded plastic stepped gear. We considered stepped gear as plate model which are fixed by two edges. While, on the other sides are free. Normal gear is calculated by Lewis formula which can be derived quite simply from the equation for the stress at the root of a cantilever beam. Stress ratio(step factor) is represented for the ratio of the bending stress of normal and the bending stress of stepped gear, and it is plotted by face width factor. This study is propose the step factor added in Dupont equation which are strength estimation of step gear

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.3
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• pp.17-23
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• 2006

The strength estimation is carried out for injection molded plastic stepped gear. The stepped gear is considered as a plate model which is fixed by two edges and freed on the other sides. The stress of common normal gear is calculated by Lewis formula which can be derived quite simply from the equation fur the stress at the root of a cantilever beam. Stress ratio(step factor) between the common normal gear and stepped gear is proposed for the ratio of the bending stress of normal gear and that of stepped gear. This study proposes the step factor added in Dupont equation which is used for strength estimation of injection molded plastic stepped gear.

• International Commerce and Information Review
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• v.10 no.3
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• pp.197-219
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• 2008

The aim of this paper is to review KORUS FTA Rules of Origin. Although there are some differences in terms of structure and contents, KORUS FTA Rules of Origin is not much different from the other FTA's texts that Korea has already concluded. Textile and Apparel chapter is also separately specified. For textile and apparel goods, Korea and the US agreed to adopt 'yam-forward rule', allowing exceptions for certain goods. Both sides also agreed to introduce procedures for permitting to use non-Party's materials when fibers ryarns rfabrics are not available in commercial quantities. Overall evaluation on KORUS FTA is considered to be positive. Economically, KORUS FTA is expected to provide good opportunities for Korean companies to access the US market. Politically, Korea and the US can take advantage of KORUS FTA to reinforce the relationship between the two countries.

• Journal of Power Electronics
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• v.12 no.2
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• pp.258-267
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• 2012

An interleaved single-stage AC/DC converter with a boost converter and an asymmetrical half-bridge topology is presented to achieve power factor correction, zero voltage switching (ZVS) and load voltage regulation. Asymmetric pulse-width modulation (PWM) is adopted to achieve ZVS turn-on for all of the switches and to increase circuit efficiency. Two ZVS half-bridge converters with interleaved PWM are connected in parallel to reduce the ripple current at input and output sides, to control the output voltage at a desired value and to achieve load current sharing. A center-tapped rectifier is adopted at the secondary side of the transformers to achieve full-wave rectification. The boost converter is operated in discontinuous conduction mode (DCM) to automatically draw a sinusoidal line current from an AC source with a high power factor and a low current distortion. Finally, a 240W converter with the proposed topology has been implemented to verify the performance and feasibility of the proposed converter.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.452-457
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• 2016

Single screw compressors are widely used in the fields of air/gas compression, refrigeration, and chemical fluid transportation systems. A single-screw compressor is composed of a screw rotor and two gate rotors located at both sides. This simple construction enables low rotational speed of the rotor, efficient compression with low noise, low vibration, and long bearing life. Despite these merits, the design method of single-screw compressors is not well known. To accelerate the industrial application of single-screw compressors, a design method using coordinate transformation is presented in this paper, and a tool trajectory is established for machining. Finally, the screw rotor, which is machined using the proposed method, is presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.11
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• pp.1085-1089
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• 2017

Juryeonggu is a cuboctahedral die that was used during the Silla period in ancient Korea. This cuboctahedral die consists of two different penal servitudes of 14 sides; however, its equal probability distribution enables it to be used as a die. In this paper, a precise cuboctahedral die, Juryeonggu, was manufactured, and its probability was measured through experiments. Next, the probability was verified through Multibody-dynamics (MBD) modeling and analysis, and the effect of the coefficient of friction on the probability distribution was studied.