• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.90-93
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• 2002

In particle radiotherapy, a shape of the beam to conform the irradiation field is statically defined by the compensator, collimator and potal devices at the outside of the patient body. However the target such as lung or liver cancer moves along with respiration. This increases the irradiated volume of normal tissue. Prior discussions about organ motions along with respiration have been mainly focused on inferior-superior movement that was usually perpendicular to beam axis. On the other hand, the change of the target depth along the beam axis is very important especially in particle radiotherapy, because the range end of beam (Bragg peak) is so sharp as to be matched to distal edge of the target. In treatment planning, the range of the particle beam inside the body is calculated using a calibration curve relating CT number and water equivalent path length (WEL) to correct the inhomogeneities of tissues. The variation in CT number along the beam path would cause the uncertainties of range calculation at treatment planning for particle radiotherapy. To estimate the uncertainties of the range calculation associated with patient breathing, we proposed the method using sequential CT images with respiration waveform, and analyzed organ motions and WELs at patients that had lung or liver cancer. The variation of the depth along the beam path was presented in WEL rather than geometrical length. In analyzed cases, WELs around the diaphragm were remarkably changed depending on the respiration, and the magnitude of these WEL variations was almost comparable to inferior-superior movement of diaphragm. The variation of WEL around the lung was influenced by heartbeat.

• Environmental Engineering Research
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• v.11 no.4
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• pp.201-207
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• 2006

A simple empirical model with good quantitative prediction of inter-particle and intra-particle distance in a cake layer with respect to ionic strength was developed. The model is an inverse length scale with functions of interaction energy and hydrodynamic factor and it explains that the inter-particle and intra-particle distance in a cake is directly related to the effective size of particles. Particle compressibility with respect to ionic strength was also predicted by the model. The model corroborated very well with experimental results of polystyrene microsphere latex particles microfiltation in a dead end operation. From the results of the model, specific cake resistance could be controlled by the same variables affecting the height of particle energy barrier described by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.143-146
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• 2002

Mg alloy is the lightest material of structural materials and is noticed for lightweight automotive parts because of excellent castability, superior ductility and damping capacity than Al alloy. But Mg Alloy is poor corrosion resistance and high temperature creep properties. In this study, Mg Matrix Composites were fabricated by squeeze casting method to improve high temperature creep properties and damping capacity. Hybrid Mg composites reinforced with Alborex, graphite particle, and SiCp was improved creep properties and damping capacity compared with Mg alloy. Compared to the length ($9\mu\textrm{m}, 27\mu\textrm{m}, 45\mu\textrm{m} etc.$), Hybrid Mg composites reinforced with SiCp, one of the most superior of the length and Alborex were more superior than those reinforced with graphite particle and Alborex in mechanical properties, creep characteristics, and damping capacity, etc.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.540-542
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• 2000

This paper describes the particle-initiated breakdown characteristics of various spacers, which have a ribbed surface, in the presence of a metallic particle. The particle was attached on the surface of each spacer. The breakdown voltages were measured by changing the length and thickness of the rib. Also the electrical field analyses were performed. As a result, the breakdown voltage of the spacer with two ribs was highest, and it was varied by the length and the thickness of the rib. Especially, in case of the rib with round edge, the breakdown voltage was higher than that with rectangular edge, which complied with the result through the field analysis.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.96-101
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• 2004

When the wind blows hard, most waves are breaking in sea. Breaking waves occur, exceeding limitation of wave steepness(wave height/wave length=l/7). Because a wave of single angular frequency couldn't generate the breaking phenomena at two dimensional ocean engineering basin, the breaking wave can be generated by the superposition of waves with various angular frequencies. We research how are the particle kinematics in the breaking wave and the magnitude of the breaking wave exciting force. We compare the force in a regular wave which has same specifications(wave height, period and length) as the breaking wave. Also the experimental results of wave exciting force and particle velocity are investigated by comparison on the analytic results using the potential theory.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1118-1121
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• 2009

We have fabricated inverted staggered pentacene Thin Film Transistor (TFT) with 1-${\mu}m$ channel length by micro contact printing (${\mu}$-CP) method. Patterning of micro-scale source/drain electrodes without etching was successfully achieved using silver nano particle ink, Polydimethylsiloxane (PDMS) stamp and FC-150 flip chip aligner-bonder. Sheet resistance of the printed Ag nano particle films were effectively reduced by two step annealing at $180^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1921-1923
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• 2000

This paper describes the particle-initiated breakdown characteristics of various spacers, which have a ribbed surface, in the presence of a metallic particle. The particles was attached on the surface of each spacer. The breakdown voltages were measured by changing the particle position on the spacer, the length and thickness of the rib. Also the electrical field analyses were performed. As a result, the breakdown voltage of the spacer with two ribs was highest, and it was varied by the length and the thickness of the rib. Especially, in case of the rib with round edge the breakdown voltage was higher than that with rectangular edge, which complied with the result through the field analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.4
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• pp.542-550
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• 1998

A direct contact heat exchanger using particle-suspended gas as a heat transfer medium is analyzed with an extended emphasis on the radiation, i. e., considering the radiation by both gas and particles. While the Runge-Kutta method is used for a numerical analysis of the momentum and energy equations, the finite volume method is utilized to solve the radiative transfer equation. Present study shows a notable effect by the gas radiation in addition to the particle radiation, especially when changing the chamber length as well as the gas and particle mass flow rate. When the gas and particle mass flow rate is raised, the gas temperature in the particle heater still increases as the gas absorption coefficient increases, which is different from the results for the small scale heat exchanger.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2037-2042
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• 2003

The purpose of this research is to develop the model of turbulence modulation due to the presence of particles in various types of particle-laden flows. Available experimental data were surveyed and the dependence of turbulence modulation of carrier-phase on particle size, concentration and particle Reynolds number were examined. This study takes into account the effect of wake produced by particle, the drag between phases and the velocity gradient in the wake to estimate the production of turbulence. The model of turbulence modulation using the mixing length theory under the assumption of equilibrium flow is proposed. Numerical results show that the model is successful in predicting the characteristics of the particle-laden flow in various conditions both qualitatively and quantitatively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.6
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• pp.813-820
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• 2003

The purpose of this research is to develop the model of turbulence modulation due to the presence of particles in various types of particle-laden flows Available experimental data are surveyed and the dependence of turbulence modulation of carrier-phase on particle size, concentration and. particle Reynolds number are examined. This study takes into account the effect of wake produced by particle, the drag between phases and the velocity gradient in the wake to estimate the production of turbulence. The model of turbulence modulation using the mixing length theory under the assumption of equilibrium flow is proposed. Numerical results show that the model is successful in predicting the characteristics of the particle-laden in various flow conditions both qualitatively and quantitatively.