• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1142-1148
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• 2006

The floating ring seal which is used in the high pressure turbo pump is frequently used in the oxidizer pump and the fuel pump of the turbo pump of the liquid propulsion rocket, because it is able to minimize clearance to decrease the leakage flow rate. But, floating ring seal has a tendency to increase the force which caused instability of system as the eccentricity ratio increases. In this paper, we devised design of floating ring seal which decrease contact area between floating and supporting ring. Modified floating ring seal has a tendency to decrease the eccentricity ratio compare with original floating ring seal. The whirl frequency ratio which is able to distinguish stability of system decrease compare with original floating ring seal

• Journal of Pharmaceutical Investigation
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• v.17 no.1
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• pp.15-21
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• 1987

Effects of phenobarbital pretreatment on the pharmacokinetics of enterohepatic recirculating griseofulvin were investigated by comparing normal to bile duct cannulated rats and also the effects of enhanced endogeneous bile flow on the absorption of griseofulvin were studied by means of in situ recirculation method in phenobarbital-pretreated rats. Phenobarbital was administered orally for five days at the dose of 75 mg/kg/day. The influence of phenobarbital pretreatment on the absorption rate constant, area under the plasma concentration-time curve, maximum plasma concentration of orally administered griseofulvin was not found in bile duct cannulated rats. Decreased absorption clearance and apparent partition coefficient of griseofulvin in accordance with the amount of endogeneous bile juice seemed to be due to the decrease of thermodynamic activity of griseofulvin as bile forms the micelle with griseofulvin.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.1-13
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• 1997

The key point that guarantees the durability of the ceramic monolith filter is to lower peak temperature and temperature gradient inside filter during regeneration. The control of the exhaust gas flow rate into the filter, by the bypass technique of the exhaust gas, enables the gas temperature in filter to be constant for regeneration. A couple of methods, which are the ON/OFF and PID control of the bypass valve, were used for feedback control of the gas temperature. These techniques showed that the ceramic filter was regenerated perfectly under the peak temperature and peak temperature gradient limitations for durability.

• International Journal of Fluid Machinery and Systems
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• v.2 no.2
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• pp.136-146
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• 2009

Small axial fans have become widely used as cooling devices in recent years. Because of their increasing importance, studies have been conducted on ways to improve the performance and reduce the noise of such fans. In this report, a small axial fan with a diameter of 85 mm (a type popularity used in personal computer or workstation) was selected for further examination. The influence on aerodynamic performance and noise of such frame design parameters as blade tip clearance results in a decrease of discrete frequency noise and an increase of broad-spectrum noise. As for the most suitable design refinement in terms of fan efficiency, we found that the treatment of outlet corner roundness and altering spoke skew to the direction counter to that of fan rotation was effective.

• Korean Journal of Clinical Pharmacy
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• v.3 no.1
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• pp.1-13
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• 1993

The intraction between cimetidine and rifampicin was studied pharmacokinetically in normal human subjects. The serum level and the area under the serum concentration curve(AUC) of rifampicin administrated orally were elevated significantly by cimetidine. Volume of distribution, total clearance and elimination rate constant of rifampicin were reduced significanyly by cimetidine. Biological half-life of rifampicin was prolonged significantly by cimetidine. The mechanism of this results is probably related to the inhibition of rifampicin metabolism(deacetyl form) or reduction of blood flow in the liver. It is desirable that dosage regimen of rifampicin shoud be adjusted when combined with cimetidine in clinical pharmacy practice.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.26-31
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• 2011

This article provides the systematic design methodology for a tilting pad journal bearing. First the dynamic factors for the bearing are selected with the critical speed analysis. The pad bearing is then designed to have its best mechanical efficiency by simulations with changing of the number of pad and the lubricant flow rate with meeting the design specifications such as metal temperature, clearance and so on. And the simulation results are reviewed to compare with an experimental test. Finally the stability of rotor with the designed bearing is investigated. This methodology is successfully applied to the rotor for 1.2MW turbo-blower.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.2
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• pp.236-243
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• 2016

This paper presents a simple thermo-physical model of reciprocating compressors for household refrigerator-freezers. The compressor model has been developed based on thermodynamic principles and large data sets from the compressor calorimeter tests. The input data are compressor geometry (displacement and clearance volume), compressor speed, suction pressure and temperature, discharge pressure, and ambient temperature. The model can estimate mass flow rate and compressor power consumption within 3.0% accuracy, which is not much larger than measurement errors associated with calorimeter testing under ideal conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.764-770
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• 1989

This paper analyze the steady state performance of a self-acting air lubricated slider bearing in hard disk/head system. Modified Reynolds' equation is derived from the steady state compressible Navier-Stokes equation, under slip-flow conditions. Finite difference technique and numerical procedure are described by using Newton-Raphson iteration method to slove the non-linear equations. These techniques are applied to conventional slider bearings and the effects of molecular mean free path(MMFP) for a recording surface of hard disk are shown. The calculation procedure developed here, wide applicabilities in practical head design procedures, and converges rapidly.

• YAKHAK HOEJI
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• v.38 no.5
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• pp.568-578
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• 1994

This study was performed in order to investigate the effect of diltiazem, which is a $Ca^{2+}$ channel blocker of benzothiazepine derivatives, on renal function in the dog. Diltiazem, when infused into the vein or carotid artery, produced the antidiuresis accompanied with the decreased excretion rates of sodium and potassium in urine$(E_{Na},\;E_K)$ and the increased reabsorption rates of sodium and potassium in renal tubules$(R_{Na},\;R_K)$. Diltiazem, when infused into a renal artery, exhibited the diuresis along with the increased renal plasma flow(RPF), osmolar clearance$(C_{osm})$, $E_{Na}$ and $E_K$, and decreased $R_{Na}$ and $R_K$ in only infused kidney. Above results suggest that diltiazem possess both antidiuretic action through central action and diuretic action by direct inhibition of electrolytes reabsorption rates in renal tubules, mainly distal tubule.

• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.396-403
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• 2018

In this paper, a high-performance and low-noise centrifugal fan is developed for cooling automotive seats which provide a driver with pleasant driving environment. First, the flow characteristics of the existing fan unit was analyzed using a fan performance tester and CFD (Computational Fluid Dynamics) simulations. The analysis of the predicted flow field indicated vortex flow near the tip of fan hub and stagnation flow on the top of fan hub. Two design points are devised to reduce the vortex flow and the stagnation flow observed in the existing fan unit. First, the cut-off clearance which is the minimum distance between the fan blade and the fan housing is increased to reduce the vortex strength and, as a result, to reduce the overall sound pressure level. Second, the hub shape is more modified to eliminate the stagnation flow. The validity of proposed design is confirmed through the numerical analysis. Finally, a prototype is manufactured with a basis on the numerical analysis result and its improved flow and noise performances are confirmed through the P-Q curves measured by using the Fan Tester and the SPL (Sound Pressure Level) levels measured in the anechoic chamber.