• Journal of Environmental Science International
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• v.7 no.6
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• pp.783-791
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• 1998

The objectives of this study were to investigate the characteristics of desulfurization under different experimental conditions and the effects of desulfurization bed fluidized bed combuster installed with the screen. The experimental results were as follows ; First, as the height of fluidized bed combustor becomes higher, the concentrations of $SO_2$ mainly increased and sulfur retion of paper sludge was higher than that of natural limestone. Second, the desulfurzation by natural limestone occurred at in-bed and the desulfurization by paper sludge occurred in the whole of fluidized bed combuster. In addition, we identified calcium sulfate by the analysis of SEM and XRD. Third, screen at splash region increased sulfur retention 2~5%, air velocity and anthracite fraction had a little effect on the sulfur retention.

• Journal of computational fluids engineering
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• v.8 no.4
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• pp.6-15
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• 2003

It is an aim of this study to perform extensive numerical study for analyzing the anisotropic turbulence effects on spatial and temporal behaviors of droplet for impinging sprays. The turbulence model of Durbin is used for comparisons with the k-ε model. The turbulence-induced dispersions of droplets are considered to describe the anisotropy of turbulence effectively and spray/wall interactions are simulated using the model of Lee and Ryou. Present study investigates the overall and the internal structures of impinging diesel sprays such as spray shapes, radius and height of wall sprays, Sauter mean diameter (SMD), local droplet velocity, and local gas velocity and compared the results with experimental data by two adopted turbulence models. When the anisotropy effect of turbulence is included, better predictions for both gas and droplet tangential velocities are obtained, compared to the k-ε model. It is concluded that anisotropic effect of turbulence should be considered for simulating impinging diesel sprays.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.77-84
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• 2003

It is an aim of this study to perform extensive numerical study for analyzing the anisotropic turbulence effects on spatial and temporal behaviors of diesel sprays after wall impingement. The turbulence model of Durbin is used for comparisons with the $k-\varepsilon$ model. The turbulence-induced dispersions of droplets are considered to describe the anisotropy of turbulence effectively and the spray/wall interactions are simulated using the model of Lee and Ryou. The present study investigates the internal structures of impinging diesel sprays such as Sauter mean diameter (SMD), loca1 droplet velocities, and local gas velocities and also compares the results predicted by two turbulence models with the experimental data. The Durbin's model considering the anisotropy of turbulence predicts both gas and droplet tangential velocities better than the$k-\varepsilon$ model does. It is concluded that the anisotropy of turbulence should be considered in simulating impinging diesel sprays.

• Journal of the Speleological Society of Korea
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• no.85
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• pp.15-17
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• 2008

This paper is attempted to review a cave restoration and preservation plan against environmental destruction and pollution as a preliminary survey for preservation of cave environment. Consequently, it's important to throw an indirect light rather than direct light on cave formations, keeping distance of 2m at least. The already existing moss should be removed using wet cloth or sponge as soon as possible. If it's washed off, be careful not to splash it or water on nearby subjects. Based on an automatic switch-off system, light will automatically turn off when no one is left in the cave. It's also recommended to dualize the cave passage and partially close the cave by taking turns to give a time to recover.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.74.1-74.1
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• 2017

The two-halo conformity is that if a central galaxy in a dark matter halo is quenched in star formation, the central galaxies in other neighboring halos (within ~ 4 Mpc) even with no causal contact seem conformed to be quenched. The galactic similarity ranging far beyond the virial radius of each dark matter halo cannot be explained by known environmental effects (ram pressure, tidal interaction, etc.). Here, using a cosmological hydrodynamic simulation, we put forward new physical origins for the phenomenon; the back-splash galaxies scenario and the halo assembly bias scenario. We discuss the relative importance of the two explanations on a quantitative basis.

• Journal of Mechanical Science and Technology
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• v.16 no.3
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• pp.376-385
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• 2002

Spray impingement and fuel film formation models with cavitation have been developed and incorporated into the computational fluid dynamics code, STAR-CD. The spray/wall interaction process was modeled by considering the effects of surface temperature conditions and fuel film formation. The behavior of fuel droplets after impingement was divided into rebound, spread and splash using the Weber number and parameter K(equation omitted). The spray impingement model accounts for mass conservation, energy conservation, and heat transfer to the impinging droplets. The fuel film formation model was developed by integrating the continuity, momentum, and energy equations along the direction of fuel film thickness. Zero dimensional cavitation model was adopted in order to consider the cavitation phenomena and to give reasonable initial conditions for spray injection. Numerical simulations of spray tip penetration, spray impingement patterns, and the mass of film-state fuel matched well with the experimental data. The spray impingement and fuel film formation models have been applied to study spray/wall impingement in high-speed direct injection diesel engines.

• Journal of Mechanical Science and Technology
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• v.15 no.3
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• pp.374-383
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• 2001

The spray/wall interaction is considered as an important phenomenon influencing air-fuel mixing in the internal combustion engines. In order to adequately represent the spray/wall interaction process, impingement regimes and post-impingement behavior have been modeled using experimental data and conservation constraints. The modeled regimes were stick, rebound, spread and splash. The tangential velocities of splashing droplets were obtained using a theoretical relationship. The continuous phase was modeled using the Eulerian conservation equations, and the dispersed phase was calculated using a discrete droplet model. The numerical simulations were compared to experimental results for spray impingement normal to the wall. The predictions for the secondary droplet velocities and droplet sizes were in good agreement with the experimental data.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.919-924
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• 2000

Spray impingement model and fuel film formation model were developed and incorporated into the computational fluid dynamics code, STAR-CD. The spray/wall interaction process were modelled by considering the change of behaviour with surface temperature condition and fuel film formation. We divided behaviour of fuel droplets after impingement into stick, rebound and splash using Weber number and parameter K. Spray impingement model accounts for mass conservation, energy conservation and heat transfer to the impinging droplets. A fuel film formation model was developed by Integrating the continuity, the Navier-Stokes and the energy equations along the direction of fuel film thickness. The validation of the model was conducted using diesel spray experimental data and gasoline spray impingement experiment. In all cases, the prediction compared reasonably well with experimental results. Spray impingement model and fuel film formation model have been applied to a direct injection diesel engine combustion chamber.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.123-126
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• 2018

자율 주행 자동차는 다수의 센서와 ECU 등으로 구성된 분산 시스템이다. 이 시스템은 다양한 시간적 제약사항들을 갖는 자율주행 응용들을 구동하며 각 응용들에 대한 시간적 제약사항 위반을 탐지해야한다. 이러한 분산 시스템에서 응용들 간의 통신을 위해 사용되는 미들웨어들 중 대표적인 것은 DDS이다. DDS는 높은 확장성을 지원하는 발행-구독 통신 모델을 기반으로 하며, 실시간성을 고려한 다양한 QoS 정책들을 제공한다. 하지만 DDS는 자율주행 응용이 요구하는 시간적 제약사항들 중 deadline과 correlation 제약 사항에 대한 위반 여부를 탐지하지 못한다. 본 논문은 DDS 기반 시스템에서 deadline과 correlation 제약 사항 위반 여부를 런타임에서 탐지하는 기법을 제안한다. 본 연구진은 제안된 기법을 DDS의 구현들 중 하나인 Vortex 사의 OpenSplice 기반 시스템에 구현하였다. 실험을 통해 검증한 결과, deadline과 correlation 제약 사항에 대한 위반 여부를 적은 오버헤드와 함께 성공적으로 탐지하였다.

• Journal of ILASS-Korea
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• v.23 no.1
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• pp.36-41
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• 2018

Fuel wall film effects power output and cycle deviation by changing the amount of fuel flowing into cylinder in PFI gasoline engines. Reduction of wall film can reduce fuel consumption and improve combustion stability. In this research, the effects of injection strategies including injection pressure and dual injection system is investigated for reducing wall film formation. The CONVERGE software is used for numerical analysis tool and O'Rourke film splash model was used for wall film prediction model. Compared with the reference case wall film decreased with increase of injection pressures, and the film formation reduced when the dual injection system was used.