• Journal of Korea Game Society
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• v.1 no.1
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• pp.42-48
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• 2001

Collision is a brief dynamic event consisting of the close approach of two or more objects or particles resulting in an abrupt change of momentum or exchange of energy because of interaction. Collisions play very important role in computer graphics, computer games and animations fields. Collisions can supply active interaction between cyberspace and real world and give much interests for making nice games so reasonable collision detection algorithms are needed. Collision detection algorithms should satisfy being fast and accuracy. In this paper, we survey the 2D collision detection algorithms between geometric models. We present several methods and system available for collision detection.

• Journal of ILASS-Korea
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• v.15 no.4
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• pp.170-176
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• 2010

This paper describes the grid-size dependency of the conventional Eulerian-Lagrangian method to spray characteristics such as spray penetration and SMD in modeling DME sprays. In addition, the reduction of the grid-size dependency of the present Gas-jet model was investigated. The calculations were performed using the KIVA code and the calculated results were compared to those of experimental result. The results showed that the conventional Eulerian-Laglangian model predicts shorter spray penetration for large cell because of inaccurate calculation of momentum exchange between liquid and gas phase. However, it was shown that the gas-jet model reduced grid-size dependency to spray penetration by calculating relative velocity between liquid and ambient gas based on gas jet velocity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.5
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• pp.422-430
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• 2001

In the present study, an evaporative generation process of ammonia-water solution film on the vertical plate was analysed. For the utilization of waste heat, hot water of low temperature was used as the heat source. The continuity, momentum, energy and diffusion equations for the solution film and vapor mixture were formulated in integral forms and solved numerically. Counter-current solution-vapor flow resulted in the refrigerant vapor of the higher ammonia concentration than that of co-current flow. Eve the rectification of refrigerant vapor was observed near the inlet of solution film in counter-current flow. For the optimum operation of generator using hot water, numerical experiments, based on the heat exchange and generation efficiencies. revealed the inter-relationships among the Reynolds number of the solution film and hot water, and the length of generator. Enhancement of heat and mass transport in the solution film was found to be very effective for the improvement of generation performance, especially at high solution flow rate.

• Particle and aerosol research
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• v.18 no.4
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• pp.129-136
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• 2022

The line width of circuits in semiconductor devices continues to decrease down to a few nanometers. Since nanoparticles attached to the patterned wafer surface may cause malfunction of the devices, it is crucial to remove the contaminant nanoparticles. Physical cleaning that utilizes momentum of liquid for detaching solid nanoparticles has recently been tested in place of the conventional chemical method. Dropwise impaction has been employed to increase the removal efficiency with expectation of more efficient momentum exchange. To date, most of relevant studies have been focused on drop spreading behavior on a horizontal surface in terms of maximum spreading diameters and average spreading velocity of drop. More important is the local liquid velocity at the position of nanoparticle, very near the surface, rather than the vertical average value. In addition, there are very scarce existing studies dealing with microdroplet impaction that may be desirable for minimizing pattern demage of the wafer. In this study, we investigated the local velocity distribution in spreading liquid film under various impaction conditions through the CFD simulation. Combining the numerical results with the particle removal model, we estimated an effective cleaning diameter (ECD), which is a measure of the particle removal capacity of a single drop, and presented the predicted ECD data as a function of droplet's velocity and diameter particularly when the droplets are microns in diameter.

• Solar Energy
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• v.10 no.3
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• pp.3-12
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• 1990

This paper deals with experimental research to increase thermal storage efficiency of hot water stored in an actual storage tank for solar application. The effect of increased energy input rate due to stratification has been discussed and illustrated through experimental data, which was taken by changing dynamic and geometric parameters. Ranges of the parameters were defined for flow rate, the ratio of diameter to height of the tank and inlet-exit water temperature difference. During the heat storage, when the flow was lower, the temperature difference was larger and the ratio of diameter to height of the tank was higher, the momentum exchange decreased. As for this experiment, when the flow rate was 8 liter/min, the temperature difference was $30^{\circ}C$ and the ratio of diameter to height of the tank was 3, the momentum exchange was minimized resulting in a good thermocline and a stable stratification. In the case of using inlet ports, if the modified Richardson number was less than 0.004, full mixing occured and so unstable stratification occured, which mean that this could not be recommended as storage through thermal stratification. Using a distributor was better than using inlet ports to form a sharp thermocline and to enhance the stratification. It was possible to get storage efficiency of 95% by using the distributor, which was higher than a storage efficiency of 85% obtained by using inlet ports in same operation condition. Furthermore, if the distributor was manufactured so that the mainpipe decreases in diameter toward the dead end to maintain constant static pressure, it might be predicted that further stable stratification and higher storage efficiency are obtainable(ie:more than 95%).

• Journal of the Korean Society of Costume
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• v.50 no.5
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• pp.25-39
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• 2000

Raoul Dufy devoted and was involved in textile design between 1910 and 1928. It was a transitional period in fashion. especially Poiret took an important role as a fashion designer at that time. After meeting Poiret, he won the fame as a textile designer rather than a painter, in his early stages, He had been deeply involved in fashion design. For instance Dufy and Poiret shared their world of art, collaborated to mount exhibitions, the Print textile fabrics by Dufy was used for dresses by Poiret and so on. The textile design which showed Dufy's artistic abilities was used as a method of expression of an exchange and a communication between art and fashion in the same period, through collaborations with Poiret. For instance, Dufy as a fauvist created and produced textile designs using his magnificent and cheerful colors and lines. He brought about a revolution in the textile design due to his participation in fashion design, as well as encouraging fashion designers. Textile design by Dufy, which grafted onto his world of art impressed Poiret greatly. It proposed the new direction of the fashion and influenced modern costume. The positive collaborate between Dufy and Poiret provided a momentum to a costume for being a part of art. Textile design as one of the important area in modern fashion needs a design originality for creating a high value-added products.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.1
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• pp.69-75
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• 2003

In this study, his technique was applied to a GDI spray in order to investigate the mixture distribution. In addition, the homogeneity degree and diffusion effect according to ambient temperature in the high pressure chamber were analyzed by using an entropy analysis method. From this experiment, we could find that entropy analysis is very effective method for the analysis of mixture formation, and the entropy values increase with the progress of uniformity in diffusion Process. we tried to provide the fundamental data for parameter which effects on the spray macroscopic characteristics with mixture ratio of diesel and gasoline. In addition, the mixture formation was analyzed by using entropy analysis. The entropy analysis is based on the concept of statistical entropy, and it identifies the degree of homogeneity in the fuel concentration. From the entropy analysis results we could find that the direct diffusion phenomena is a dominant factor in the formation of a homogeneous mixture at downstream of GDI spray especially in vaporizing conditions. As to increasing ambient temperature and increasing gasoline rate, the entropy intensity using the statistic thermodynamics method is increased because evaporation rate is higher gasoline than diesel.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.4
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• pp.478-486
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• 2007

Numerical analysis had been performed to understand flow characteristics of the flue gas and slurry in the absorber of a flue gas desulphurization (FGD) system using computational fluid dynamics (CFD) technique. Two-fluid(Euler-Lagrangian) model had been employed to simulate physical phenomenon, which slurry particles injected through slurry spray nozzles fall down and bump into the flue gas inflowing through inlet duct. It was not necessary to adopt pre-defined pressure drop inside the absorber because interaction between flue gas and slurry particles was considered. Hundreds of slurry spray nozzles were considered with the spray velocity at the nozzles, swirl velocity and spreading angle. The results note that the flow disturbance of flue gas is found at the bottom of the absorber, and the current rising with high speed stream is observed in the opposite region of the inflow duct. The high speed stream is reduced as the flue gas goes up, because the high speed stream of flue gas dumps falling slurry particles due to momentum exchange between flue gas and slurry particles. In spite of some disproportion in slurry distribution inside the absorber, escape of slurry particles from the absorber facility is not observed. The pressure drop inside the absorber is mainly occurred at the bottom section.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.3
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• pp.131-139
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• 2009

The simulation of refrigeration cycle is important since the experimental approach is costly and time-consuming. The present paper focuses on the simulation of a refrigeration cycle equipped with a capillary tube-suction line heat exchanger(SLHX), which is widely used in small vapor compression refrigeration systems. The present simulation is based on fundamental conservation equations of mass, momentum, and energy. These equations are solved through an iterative process. The non-adiabatic capillary tube model is based on homogeneous two-phase flow model. This model is used to understand the refrigerant flow behavior inside the non-adiabatic capillary tube. The simulation results show that both of the location and length of heat exchange section influence the coefficient of performance (COP).

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.10
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• pp.2738-2750
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• 1994

The Effects of radiative heat transfer on turbulent flow in a partitioned enclosure is studied numerically. The enclosure is partially divided by a thin, poorly conducting vertical divider projecting from the ceiling of the enclosure. The low Reynolds number $k-{\epsilon}$ model is adopted to calculate the turbulent flow field. The solutions to the radiative transfer equations are obtained by the discrete ordinates method(DOM). This method is based on control volume method and is compatible with the SIMPLER algorithm used to solve the momentum and energy equations. The effects of optical thickness and Planck number on the flow, temperature fields and heat transfer rates are investigated for a moderate Rayleigh number($=10^9$). The changes in buoyant flow fields and temperature distributions due to the variation of baffle length are also analyzed. From the predictions, radiant heat exchange between the baffle and the sidewalls strongly influences the temperature distribution in the baffle and its vicinity and total heat transfer increases as the optical thickness and the baffle length decrease. It is possible to neglect the radiative heat transfer effect when Planck number is over one.