• Journal of the Society of Naval Architects of Korea
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• v.47 no.2
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• pp.113-121
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• 2010

Recently, as container ships become larger and faster, rudder cavitations are more frequently observed near the gap between the horn and rudder plates of the ships to cause serious damages to the rudder surface of the ship. The authors already have suggested through a series of model experiments and numerical computations that employment of an appropriate blocking device for gap flow may retard the gap cavitation. For examples, a cam device installed near the outer edges of the vertical gap or a water-injection device combined with a pair of half-round bars installed inside the gap can considerably reduce the gap cavitation. However, it is also found that effective blocking of the flow through the vertical gap results in growth of the cavitation near the horizontal gap instead. In the present study, effectiveness of the simultaneous blocking of the flow through the horizontal and vertical gaps of a horn type rudder in minimizing the damage by gap cavitation is studied. Additional blocking disks are inserted inside the horizontal gaps on the top and bottom of the pintle block and numerical computations are carried out to confirm the combined effect of the blocking devices.

• Journal of the Korean Geotechnical Society
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• v.21 no.4
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• pp.31-40
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• 2005

This study proposed a new yield function considering the spacing ratio of the critical state to predict the undrained shear behavior of anisotropic field ground. We have suggested a nonassociated constitutive model that used a newly modified plastic potential function in order to apply the yield function of the modified Cam-Clay model to the anisotropic consolidation. In this paper, we predicted undrained shear behavior of the remolded weathered mudstone soils in Phohang isotorpically and anisotropically consolidated using the suggested model. To evaluate the reliability of proposed model, we predictied undrained shear behavior of Bankok Clay isotropically, nomally consolidated and Drammen Clay Ko consolidated. The predicted results are consistent with the observed behavior.

• Geotechnical Engineering
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• v.8 no.2
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• pp.45-58
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• 1992

An elasto-plastic constitutive model for geological materials, which satisfies the flezibility and stability at the same time, can be used in a number of geotechnical problems. Using the spacing ratio of critical state, a flexible model is proposed based on the stability of modified Camflay model. The spacing ratio of critical state can be simply evaluated, and practically used in describing the undrained shearing behavior of clay. The proposed model has precisely predicted the stress paths and stress -strain relationships, compared with the modified Camflay model, with respect to undrained triaxial test results. Besides, the effects of strain rate, creep, and relaxation can also be considered. Using the quasi-state boundary surface, the constitutive relations are well predicted. Therefore, it is found that the assumption of associative flow rule is well posed for undrained behavior of normally consolidated clay.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.18-24
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• 2009

The most dominate aspect in machine works using CNC devices in industrial production processes is the precision of the product and the Cycle Time. To this day, many studies on the external factors of the technology to reduce the Cycle Time have advanced amid to the advancements in cam soft development for manual programs and the numerous studies on high speed and precision machining. This study experimented various functions of the sequence pattern flow and arranged system development technologies of past few years to develop and applicate various usage of adjustment factors within the CNC, so it would be more understandable to the user and would enable them to make high speed and precision products more faster develop and. In order to reduce the Cycle Time, the mechanism of machine tools has to be analysed and applied, in addition to program reduction and improvement of the manufacture process.

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.132-134
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• 2005

The CC chemokine, monocyte chemoattractant protein-1 (MCP-1), plays a crucial role in the initiation of atherosclerosis and has direct effects that promote angiogenesis. To develop a specific inhibitor for MCP-1-induced angiogenesis, we performed in vitro selection employing phage display random peptide libraries. Most of the selected peptides were found to be homologous to the second extracellular loops of CCR2 and CCR3. We synthesized the peptide encoding the homologous sequences of the receptors and tested its effect on the MCP-1 induced angiogenesis. Surface Plasmon Resonance measurements demonstrated specific binding of the peptide to MCP-1 but not to the other homologous protein, MCP-3. Flow cytometry revealed that the peptide inhibited the MCP-1 binding to THP-1 monocytes. Moreover, CAM and rat aortic ring assays showed that the peptide inhibited MCP-1 induced angiogenesis. Our observations indicate that the MCP-1-binding peptide exerts its anti-angiogenic effect by interfering with the interaction between MCP-1 and its receptor.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.1
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• pp.91-96
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• 2002

Recently industry has moved towards automated operations with the goal of achieving better product quality greater productivity and reliability The pump design in characterized by extensive utilization of the related database which contains performance data. The inputs to the system are through interactive dialogue sessions and the basic input consist of flow rate, head, of fluid efficiency and the customer special requirements. These basic inputs along with the numerous rules in the knowledge bases and the mathematical modeling enable the effective design of the pump industry This paper represents the development of an automatic pump design system that was composed of a main program the data input module the drawing module the drawing edit module and was programed by the AutoLISP language under the Auto CAD program The developed system ultimately generates the design for a pump through the AutoCAD language.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.5
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• pp.395-401
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• 2014

Development of five axis tool grinding machine and CAD/CAM systems increase tool design flexibility. In this research, investigated are cutting characteristics of ball-end mill with different helix angle. Special WC ball-end mills with $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$ helix angles are designed and used in various cutting tests. Machining performance according to helix angle variation is evaluated from cutting forces, surface roughness, tool wear, produced chip shape, and vibration characteristics. The ball-end mill with $10^{\circ}$ helix angle shows the best cutting performance due to appropriate chip load distribution and smooth chip flow. This research can be used for cutting edge geometry optimization and novel design of ball-end mill.

• International Journal of CAD/CAM
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• v.8 no.1
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• pp.63-67
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• 2009

This paper puts forward a method based on the boundary deformation for planar grid generation. Many methods start with the special properties of grid and switch to the solution of a direct optimization or a non-linear minimum cost flow. Though with high theoretical significance, it's hard to realize due to the extremely complicated computing process. This paper brings out the automatic generation of planar grid by studying the boundary deformational properties of planar grid, which leads to uniform grid and enjoys the simplicity of computation and realization.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.983-988
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• 2004

In the present study, the effects of orthogonal ribs on structural warpage during injection molding process were investigated. Basic ribbed models for the evaluation of degree of warpage were introduced and designed. Injection molds for these models are manufactured based on the full 3D CAD/CAM technology and specimens are prepared for experiment. Numerical analysis using commercial plastic injection molding analysis software was also performed to compare the results with experimental ones. The variations of materials and parameters such as injection time, mold temperature, melt temperature, holding time were considered in the present work. It was shown that orthogonal ribs have significant effect on the reduction of warpage during the injection molding process.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.330-336
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• 1989

In analyzing the axisymmetric backward extrusion process a new method of analysis using upper-bound theorem is proposed in which the plastic zone and dead metal zone cam be predicted. Experiments are carried out with commercial aluminum. The metal flow on the meridional plane has been visualized experimentally by using the gridded specimens. It is shown that the theoretical results both in extrusion load and deformation pattern are in good agreement with the experimental results and they can be used for effective punch and die design to consider various process parameters in axisymmetric backward extrusion.