• Nuclear Engineering and Technology
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• v.42 no.1
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• pp.73-78
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• 2010

The suppression of molten salt vaporization is one of the key technical issues in the electrolytic reduction process developed for recycling spent nuclear fuel from light-water reactors Since the Hertz-Langmuir relation previously applied to molten salt vaporization is valid only for vaporization into a vacuum, a diffusion model was derived to quantitatively assess the vaporization of LiCl, $Li_2O$ and Li from an electrolytic reducer operating under atmospheric pressure. Vaporization rates as a function of operation variables were calculated and shown to be in reasonable agreement with the experimental data obtained from thermogravimetry.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.155-164
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• 2004

In order for studying pressure-coupled dynamic responses of droplet vaporization, open-loop experiment of an isolated droplet vaporization exposed to pressure perturbations in stagnant gaseous environment is numerically conducted, Governing equations are solved for flow parameters at gas and liquid phases separately and thermodynamic parameters at the interfacial boundary are matched for problem closure. For high-pressure effects, vapor-liquid interfacial thermodynamics is rigorously treated. A series of parametric calculations in terms of mean pressure level and wave frequencies are carried out employing a n-pentane droplet in stagnant gaseous nitrogen. Results show that wave instability in view of pressure-coupled vaporization response seems more susceptible at higher pressures and higher wave frequencies. Mass evaporation rate responding to pressure waves is amplified with increase in pressure due to substantial reduction in latent heat of vaporization. Augmentation of perturbation frequency also enhances amplification due to the reduction of phase differences between pressure perturbation and surface temperature fluctuation.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1286-1291
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• 2004

In order for studying pressure-coupled dynamic responses of droplet vaporization, open-loop experiment of an isolated droplet vaporization exposed to pressure perturbations in stagnant gaseous environment is numerically conducted. Governing equations are solved for flow parameters at gas and liquid phases separately and thermodynamic parameters at the interfacial boundary are matched for problem closure. For high-pressure effects, vapor-liquid interfacial thermodynamics is rigorously treated. A series of parametric calculations in terms of mean pressure level and wave frequencies are carried out employing a n-pentane droplet in stagnant gaseous nitrogen. Results show that wave instability in view of pressure-coupled vaporization response seems more susceptible at higher pressures and higher wave frequencies. Mass evaporation rate responding to pressure waves is amplified with increase in pressure due to substantial reduction in latent heat of vaporization. Augmentation of perturbation frequency also enhances amplification due to the reduction of phase differences between pressure perturbation and surface temperature fluctuation.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1122-1127
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• 2004

an isolated droplet combustion exposed to pressure perturbations in stagnant gaseous environment is numerically conducted. Governing equations are solved for flow parameters at gas and liquid phases separately and thermodynamic parameters at the interfacial boundary are matched for problem closure. For high-pressure effects, vapor-liquid interfacial thermodynamics is rigorously treated. A series of parametric calculations in terms of mean pressure level and wave frequencies are carried out employing a n-pentane droplet in stagnant gaseous air. Results show that the operating pressure and driving frequency have an important role in determining the amplitude and phase lag of a combustion response. Mass evaporation rate responding to pressure waves is amplified with increase in pressure due to substantial reduction in latent heat of vaporization. Phase difference between pressure and evaporation rate decreases due to the reduced thermal inertia at high pressure. In addition to this, augmentation of perturbation frequency also enhances amplification of vaporization rate because the time period for the pressure oscillation is much smaller than the liquid thermal inertia time. The phase of evaporation rate shifts backward due to the elevated thermal inertia at high acoustic frequency.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.1
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• pp.131-139
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• 1999

Experimental investigations on flame spread in droplet arrays have been conducted under supercritical ambient pressures of fuel droplet. Flame spread rates are measured for n-Decane droplet of diameters of 0.75 and 1.0mm, using high speed images of OH chemiluminescence up to 3.0MPa. The pattern of flame spread is categorized into two: a continuous mode and an intermittent one. There exists a limit droplet spacing, above which flame spread does not occur. Flame spread rate with the decrease of droplet spacing increases and then decreases after takin& a maximum. It is also seen that there exists a limit ambient pressure, above which flame spread does not occur. Flame spread rate decreases monotonically with the increase of ambient pressure. Exceptionally, In the case of a small droplet spacing, flame spread with the increase of ambient pressure is extended to supercritical pressures of fuel droplet. This is caused by enhanced vaporization with the increase of ambient pressure. Consequently, in flame spread with droplet droplet spacing, the relative position of flame to droplet spacing plays an important role. The monotonic decrease with ambient pressure is mainly related to the reduction of flame radius in subcritical pressures and the extension to supercritical pressures of flame spread is caused by the reduction of ignition time of unburnt droplet due to the enhanced vaporization at supercritical pressures.

• Archives of Plastic Surgery
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• v.42 no.1
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• pp.52-58
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• 2015

Background The erbium:yttrium scandium gallium garnet (Er:YSGG) laser differs from other laser techniques by having a faster and higher cure rate. Since the Er:YSGG laser causes an appropriate proportion of ablation and coagulation, it has advantages over the conventional carbon dioxide ($CO_2$) laser and the erbium-doped yttrium aluminum garnet (Er:YAG) laser, including heating tendencies and explosive vaporization. This research was conducted to explore the effects and safety of the Er:YSGG laser. Methods Twenty patients participated in the pilot study of a resurfacing system using a 2,790-nm Er:YSGG laser. All patients received facial treatment by the 2,790-nm Er:YSGG laser system (Cutera) twice with a 4-week interval. Wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture were measured. Results Study subjects included 15 women and five men. Re-epithelization occurred in all subjects 3 to 4 days after treatment, and wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture within 6 months of treatment. Conclusions The 2,790-nm YSGG laser technique had fewer complications and was effective in the improvement of scars, pores, wrinkles, and skin tone and color with one or two treatments. We expect this method to be effective for people with acne scars, pore scars, deep wrinkles, and uneven skin texture and color.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.581-590
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• 2008

A SWP method is a revolutionary dewatering method. The conventional dewatering method, deep-well method, had ever occurred a civil appeal caused by the well depletion in compliance with the reduction of the groundwater level over a wider area considerably by the deep-well pumping from homogeneous sand-layer ground for a dry-work, while pump groung excavation working in Sendai city, Japan 10 years ago. it'd developed with the problematic proposal to find the new method which can lower the groundwater level only within the sheet pile without any reduction of groundwater outside of the sheet pile and until currently steady improvement came. It's been confirmed with plenty of executional results that there was almost no decreasing of water-level from surroundings, over so many construction-sites including vertical shafts which completely does not enter into non-water permeable layer and pumping ground etc. The SWP method in this time has been introducing initially and carried into a the execution tentatively at a construction-site and made a various result get through the execution.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.10
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• pp.737-747
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• 2009

This study is to investigate the effect of the moisture, volatile matter and particle size in the coal on the pulverized coal combustion characteristics using CFD. The results show that as the moisture content in coal increases, flame temperature decreases because of heat loss driven from latent heat of vaporization and reduction of heating value. As the volatile matter content in the coal increases, the temperature in the region near the burner increases, while the temperature in rear region of boiler decreases. The solution to keep the temperature in the rear region of boiler is suggested that particle size is needed to be larger. As the particle size increases, the temperature in the rear region of boiler show tendency to increase, for combustion burning time of coal could be extended.

• Journal of Power System Engineering
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• v.12 no.5
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• pp.14-19
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• 2008

In order to meet stringent future emission regulations, especially to reduce Particulate Matter (PM) and NOX, stoichiometric diesel combustion technology with a piezo group-hole nozzle injector is being researched for reduction harmful emissions. A new nozzle layout, namely a group-hole nozzle, which has one group of small orifices with a wide spray included angle was investigated to improve the efficiency of stoichiometric diesel combustion. From this point of view, the group-hole nozzle suggested by Dense Co. is an attractive candidate method applicable to stoichiometric diesel combustion. The group-hole nozzle concept is to reduce the injector nozzle hole diameters without sacrificing spray penetration by closely locating two holes. Experimental studies have proven that the spray from group-hole nozzles have similar spray penetration to that of a single hole with equivalent overall nozzle hole area, but the spray drop sizes (SMD) are reduced, aiding vaporization and mixing.

• Journal of the Korean Geosynthetics Society
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• v.18 no.1
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• pp.79-89
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• 2019

The field measurement and laboratory experiment were conducted to investigate the effect of reducing the surface temperature of the functional aspect of the heat island phenomenon of the permeable block which is made the recycled synthetic resin rather than the existing concrete permeable block. Field measurement was taken for 3 days in consideration of dry condition and wet condition and laboratory experiment was divided into dry condition, rainfall simulating condition, and wetting condition. The variations of temperature and the evaporation rate of water moisture content after experiment were confirmed. As a result of field measurement, it is confirmed that the surface temperature decreases due to the difference in albedo of the pore block surface rather than the cooling effect due to the latent heat of vaporization. The evaporation of moisture in a dry state where drought persisted or a certain level of moisture was not maintained in the surface layer. As a result of laboratory experiment, resin permeable block gives higher surface temperature when it is dry condition than concrete permeable block, but the evaporation of water in the pore is kept constant by capillary force in rainfall simulation condition, and higher temperature reduction rate. As a result of measuring the evaporation rate after laboratory experiment, it is confirmed that the effect of reducing temperature is increased as the evaporation rate of water is higher. Based on these results, correlation formula for evaporation rate and temperature reduction rate is derived.