• Water for future
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• v.20 no.4
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• pp.279-284
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• 1987

An improved mathematical model is presented which will predict the initial minimum dilution and terminal rise height of wastewater discharged from ocean outfalls into density stratified water flowing at an arbitary direction and speed. Solutions are derived for discharge into linearly stratified water, based on three-dimensional experimental work on line plumes in unstratified currents. The effects of current speed, direction, stratification and type of nozzle are discussed, and the model predictions are compared to laboratory experiments.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2751-2755
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• 2011

The visible vibronic emission spectrum was recorded from the corona discharge of precursor 1,2,3,4-tetramethylbenzene with a large amount of inert carrier gas helium using a pinhole-type glass nozzle coupled with corona excited supersonic expansion. The spectrum showed a series of vibronic bands in the $D_1{\rightarrow}D_0$ electronic transition of jet-cooled benzyl-type radicals formed from the precursor in a corona excitation. The analysis confirmed that two isomeric radicals, 2,3,4- and 2,3,6-trimethylbenzyl radicals, were produced as a result of removal of a hydrogen atom from the methyl group at different substitution positions. For each isomeric product, the electronic transition and a few vibrational mode frequencies were determined in the ground electronic state.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.451-454
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• 1989

A DC thermal plasma generation system for both LPPS and APPS was designed and its characteristics was analysed. Discharge experiments for 60 conical and cylindrical type anode nozzle were conducted and the results were compaerd each other. The flow dependence and the electrode gap dependence were precisely explained and especially voltage jump phenomena under the existance of the parallel magnetic field was studid.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.199-204
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• 2003

In the present study, the compression process in scroll compressor was simulated in consideration of flow leakage and heat transfer. Tangential and radial leakages of the refrigerant between the scrolls were considered as nozzle flow. The experiment was first conducted with a scroll compressor for automobile air conditioning system and R134a as a refrigerant. Temperature and pressure were measured at the suction and discharge ports of the compressor to determine the thermodynamic states of the refrigerant flow. Temperature distribution of the scroll with the involute angle was also measured by thermocouples that were installed inside the scroll. Measured temperature distribution was compared with the numerical results. From this result, the thermal effect of mechanical contact was found to be important in heat transfer of the compression process.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2783-2785
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• 2010

Searching for new molecular radicals which are believed to play an important role as reaction intermediates in aromatic chain reactions, we have applied the technique of corona excited supersonic expansion employing a pinhole-type glass nozzle to obtain the vibronic spectrum from the corona discharge of precursor 3,5-difluorotoluene with a large amount of inert carrier gas helium. An analysis of the observed spectrum revealed that many vibronic bands are from other isomeric difluorobenzyl radicals generated in the jet by migration of the fluorine atom or methylene group to the adjacent position in the 3,5-difluorobenzyl radical. A possible mechanism was proposed for the formation of other isomers by using a bridged cyclic intermediate structure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.12
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• pp.931-937
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• 2008

A high motive pressure thermal vapor compressor(TVC) for a commercial multi-effect desalination(MED) plant is designed to have a high entraining performance and its robustness is also considered in the respect of operating stability at the abrupt change of the operating pressures like the motive and suction steam pressure which can be easily fluctuated by the external disturbance. The TVC having a good entraining performance of more than entrainment ratio 6.0 is designed through the iterative CFD analysis for the various primary nozzle diameter, mixing tube diameter and mixing tube length. And then for a couple of TVC having a similar entrainment ratio, the changes of the entrainment ratio are checked along the motive and suction pressure change. The system stability is diagnosed through the analyzing the changing pattern of the entrainment ratio.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.3
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• pp.1-10
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• 2000

In order to predict the performance of subsonic/sonic ejector system and to provide fundamental data for a cost effective design, one dimensional gas dynamics theory was applied to the subsonic and sonic ejector systems with the second throat. In the current theoretical analyses, ejector throat area ratio, mass flow ratio and secondary stagnation pressure were derived as a function of the operating pressure ratio of the ejector, and the discharge coefficient of the primary nozzle and the loss coefficient of the diffuser were incorporated into the whole performance of the ejector system. The results of theoretical analysis can be applied to practical industrial use of subsonic and sonic gas ejector systems.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.105-111
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• 2005

An experimental study is performed for extinguishing of n-heptane pool fire by water mist containing potassium acetate as a fire suppression additive. Water mist was generated by a single pressure nozzle in a small-scale chamber. The drop size distribution of water mist was measured using laser diffraction(Malvern particle sizer). The flame temperature, oxygen concentration and carbon monoxide concentration were measured. In case of using additives, the fire extinguishing time was shorter than that of pure water at a given discharge pressure and it was because the momentum of a water droplet containing additives was increased. And also dissociated metal atoms, potassium, were reacted as a scavenger of the major radical species OH, H which were generated for combustion process. Moreover, at a high pressure of 4MPa, the fire was extinguished through blowing effect as well as primary extinguishing mechanisms.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.163-170
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• 1997

End milling experiments are conducted to investigate characteristics of acoustic emission (AE) and cutting force singals due to tool fracture. The AE signals are obtained with a sensor attached to cutting fluid discharge nozzle. Tool states are identified with scanning electron microscopy and optical microscopy. It is demonstrated that the AE signals provide reliable informations about the cutting processes and tool states. Morever, tool fracture can be detected successfully using both the AE count rate and the standard deviation of principal cutting force.

• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.111-118
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• 2013

The influence of gas flow on the plasma generation in the atmospheric plasma jet is described with the theory of hydrodynamics. The plasma discharge is affected by the gas-flow streams with Reynolds number (Re) as well as the gas pressure with Bernoulli's theorem according to the gas flow rate inserted into the glass tube. The length of plasma column is varied with the flow types such as the laminar flow of Re<2,000 and the turbulent flow of Re>4,000 as it has been known in a general fluid experiments. In the laminar flow, the plasma column length is increased as the increase of flow rate. Since the pressure in the glass tube becomes low as the increase of flow velocity by the Bernoulli's theorem, the breakdown voltage of plasma discharge is reduced by the Paschen's law. Therefore, the plasma length is increased as the increasing flow rate with the fixed operation voltage. In the transition of laminar and turbulent flows, the plasma length is decreased. When the flow becomes turbulent as the flow rate is increasing, the plasma length becomes short and the discharge is shut down ultimately. In the discharge of laminar flow, the diameter of plasma beam exposed on the substrate surface is kept less than the glass diameter, since the gas flow is kept to the distinct distance from the nozzle of glass tube.