• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.411-417
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• 2009

The constant volume flow meter system (the chamber volume in the 22 L class) was developed to estimate the pumping speed of the dry pump used for the industry of the next generation semiconductor and display. In order to insure the validity of the system, The base pressure and the leak rate in the enclosed system were checked, which were the $6{\times}10^{-8}\;mbar$ and $1.5{\times}10^{-6}\;mbar-L/s$, respectively. Furthermore, it is also confirmed that the value of throughput limit in this system was as much as 1 order of magnitude lower than that in a previously developed system in the 875 L class. By using this developed system, the pumping speed of the new small dry pump was measured. It is believed that the new developed system can be alternating the expensive constant pressure flow meter system in the range of $1{\times}10^{-2}\;mbar-L/s{\sim}1{\times}10^{-3}\;mbar-L/s$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.10
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• pp.833-839
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• 2013

Thermal vacuum test should be performed prior to launch to verify satellites' functionality in a harsh space environment which is represented by extremely cold temperatures and vacuum conditions. A thermal vacuum chamber which consists of a vacuum vessel, a pumping system, and a thermal control system are used to perform thermal vacuum tests of a satellite system and its components. A cryogenic blower is a core component of the closed loop thermal control system for thermal vacuum chambers. This paper describes the fan design of the cryogenic blower, the design of the thermal protection interface between the driving part and the fluid part, which were verified by thermal and structural analyses. The performance of the cryogenic blower is confirmed by similarity test on the test bench.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1128-1138
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• 2000

Pumping action in ejector systems is generally achieved through the mixing of a high-velocity and high-energy stream with a lower-velocity and lower-energy stream within a duct. The design and performance evaluation of the ejector systems has developed as a combination of scale-model experiments, empiricism and theoretical analyses applicable only to very simplified configurations, because of the generic complexity of the flow phenomena. In order to predict the detailed performance characteristics of such systems, the flow phenomena throughout the operating regimes of the ejector system should be fully understood. This paper presents the computational results for the two-dimensional supersonic ejector system with a second throat. The numerical simulations are based on a fully implicit finite volume scheme of the compressible Reynolds-averaged Navier-Stokes equation in a domain that extends from the stagnation chamber to the diffuser exit. For a wide range of the operating pressure ratio the flow field inside the ejector system is investigated in detail. The results show that the supersonic ejector systems have an optimal throat area for the operating pressure ratio to be minimized.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.12
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• pp.132-138
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• 2008

Recently, mastering processes for high density optical disc such as Blu-ray disc rely on electron beams, which are operable in only vacuum. In the mastering process, one of the most important tasks is to design precision stages for providing precise positioning of the works with respect to the source in a high vacuum environment. In this paper, we have developed a precision rotation table usable in the electron beam mastering. The rotation table adopted air bearings for a high positioning repeatability and velocity stability. The air leakage from the air bearings has been minimized by employing the differential exhaust scheme using three steps of air drain. The design parameters such as diameters of exhaust lines, seal lengths, and pumping speeds were decided according to the optimization method using genetic algorithm. The performance on the vacuum level of the rotation table was evaluated experimentally and theoretically. The results indicate that a vacuum level of $10^{-4}$ Pa is achieved with operation of air bearings in a vacuum chamber, which is sufficient for the electron beam mastering.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.3
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• pp.127-133
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• 2017

Performance analysis has been carried out on a high side scroll compressor that had a fixed scroll equipped with a circular oil groove on its thrust surface. Oil was supplied to the oil groove through an intermittent opening from a high pressure oil reservoir formed inside the orbiting scroll hub. Oil in the groove was then delivered to both suction and back pressure chambers by pressure differentials and viscous pumping action of the orbiting scroll base plate. Mathematical modeling of this oil groove system was incorporated into a main compressor performance simulation program for an optimum oil groove design. The study findings were as follows. Pressure in the oil groove can be controlled by changing its configuration and the oil passage area. With an enlarged oil passage, the pressure in the oil groove heightens due to an increased flow rate, but the pressure elevation in the back pressure chamber is small, resulting in reduced friction loss at the thrust surface between the two scrolls. On the other hand, by increasing the oil passage area, the oil content in the refrigerant flow increases. Considering all these factors, the energy efficiency ratio could be improved by about 3.6% under the ARI condition by an optimal oil groove design.

• Journal of Information Display
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• v.2 no.4
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• pp.34-38
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• 2001

We suggested new PDP packaging technology using the direct joint method, which does not need an exhausting hole and tube. The advantages of this method are simple process, short process time and time panel package. To packaging, we drew the seal line of glass frit by dispenser followed by forming the lump, which provide pumping-out path during the packaging process. And, we have performed a pretreatment of glass frit to reduce the out-gases. After which, both front and rear glass plates were aligned and loaded into vacuum packaging chamber. The 4-inch monochrome AC-PDP was successfully packaged and fully emitted with brightness of 1000 $cd/m^2$. Also, glass frit properties for pretreatment condition was investigated by AES and SEM analyses.

• Journal of The Korean Dental Society of Anesthesiology
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• v.12 no.1
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• pp.45-50
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• 2012

The Fontan operation is a heart operation used to treat complex congenital heart defects like tricuspid atresia, hypoplastic left heart syndrome, pulmonary atresia and single ventricle. A single ventricle is dedicated to pumping oxygenated blood to the systemic circulation and the entire systemic venous return reaches the pulmonary arterial system without the direct influence of a pumping chamber. In the patient with Fontan operation, it is important to achieve adequate pulmonary blood flow and cardiac output in anesthetic management. In this case, a 10-year-old boy (19.6 kg, 114 cm) with cleft palate, cerebral palsy and severe mental retardation, who underwent a Fontan operation when he was 4 years old, was presented for deep sedation. Because he was suffering from eating disorder with cleft palate, the orthodontist and the plastic surgeon planned to insert intraoral orthodontic device before cleft palate repair. But it was impossible to open his mouth for alginate impression procedure. After careful pre-anesthesia evaluation we planned to administer deep sedation with propofol infusion. After Intravenous catheter insertion, we started propofol intravenous infusion with the formula of a loading dose of 1.0 mg/kg followed by an infusion rate of 6.0 mg/kg/hr with syringe pump. His blood pressure was remained around 80/40 mmHg after loss of consciousness, but he could not maintain his airway patent. So we lowered the infusion rate to 3.0 mg/kg/hr, immediately. The oxygen saturation was maintained above 95% with nasal oxygen supply, and blood pressure was maintained around 100-80/60-40 mmHg. After the sedation of 110 minutes with propofol (the infusion rate to 3.0-5.0 mg/kg/hr), he fully regained consciousness, and was discharged without complication after 1 hour observation. In case of post-Fontan patient, intravenous deep sedation with propofol was safe and effective method of behavioral management during dental treatment.

• Journal of the Korean Vacuum Society
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• v.13 no.4
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• pp.139-144
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• 2004

Recently, the importance of clean vacuum and partial pressure measurement of gas species has been increased in the vaccum process. In this study, the partial pressures of $H_2$, He, C, N, $O_2$, $H_2O $, Ar/2, $N_2$(CO), Ar, $CO_2$ were measured by residual gas analyzer according to temperature of cryogenic pump which is used to clean vacuum generation and compared. The experimental results showed that the cryopanel temperature was reached to 12K after 72 minutes of pumping and after 25hours, the partial pressures in percent were 24.9 %, 6.6%, 5.5 %, 2.2 %, 3.8%, 30.7%, 6.5%, 6.1 %, 5.5%, 8.2% for $H_2$, He, C, N, $O_2$, $H_2O $, Ar/2, $N_2$, Ar, $CO_2$ respectively. The dominant gases were $H_2$ and $H_2O $, and the partial pressures were relatively high compare to other gases.

• 한국해양학회지
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• v.26 no.4
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• pp.324-331
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• 1991

Laboratory experiments were undertaken in mixing chamber to study the water-in-oil emulsion formation tendency, stability and formation rate of 16 crude oils. Arabian, Iran, Dubai, Isthmus and Daekyung crudes showed high emulsion formation tendency and had water contents of 80-90%. Emulsions of crude oils of middle East were very stable, while Isthmus and Daekyung sudes formed unstable emulsion. Emulsion formation tendency rate, and stability showed significant correlations with asphaltene content of crude oil. To evaluate the possibility of preventing mousse formation, inhibition ability of several dispersants and demulsifier was tested. They inhibited mousse formation at 0.1-0.2% concentrations (v/v). Emulsion inhibition by chemical treatment delayed the time of formation, but did not decrease water content. Demulsifying ability of dispersants and demulsifier was tested because biscous emulsion causes formidable problems in skimming, pumping and recovery operation. British demulsifier Alcohol 0 showed excellent emulsion breaking efficiency at 0.1% of emulsion Vol..

• Journal of the Korean Vacuum Society
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• v.15 no.3
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• pp.314-324
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• 2006

The vacuum characteristics of the KSTAR ICRF antenna were experimentally investigated. The fabricated antenna was installed in the RF Test Chamber(RFTC) which has a vacuum system with an effective pumping speed of 1015 l/s. The time variations of RFTC pressure, total gas load and ultimate pressure were measured before the RF test. RF conditioning effect was studied by repeating RF pulses at low power level. A time variation of the RFTC pressure was measured during a RF power was applied to the antenna. Threshold pressure at which a RF breakdown occurs was investigated. Whenever the pressure was higher than $10^{-4}$ mbar, the RF breakdown occurred. During a long pulse testing, the temperature of the antenna and RFTC pressure were measured to investigate long pulse limitation of the maximum available voltage without any cooling, which were compared with testing results with a water cooling of the antenna.