• The Korean Journal of Pharmacology
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• v.10 no.2
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• pp.63-74
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• 1974

This study was carried out to observe the direct effect of hydrocortisone on renal function by infusing it into a renal artery. Hydrocortisone (5mg/kg) or saline (0.5 ml/kg) was infused directly into the left renal artery of the rabbit, the right kidney was left intact to serve as a control for general action of acetazolamide (10 mg/kg) or aminophylline (10 mg/kg), which was administered intravenously 30 minutes after the direct infusion of pretreated drugs (hydrocortisone or saline). The changes of urine volume, pH, urinary excretion rates of $Na^+,\;K^+\;and\;Cl^-$, and the clearances of inulin and PAH were measured at an interval of 10 minutes for half an hour after the direct infusion of hydrocortisone or saline, and for one hour after intravenous administration of acetazolamide or aminophylline. The results of the experiment were as follows: 1. Significant changes in urine volume and urinary electrolytes (excreted rates of $Na^+,\;K^+\;and\;Cl^-$) were observed in the hydrocortisone-infused group 10 minutes after the administration of acetazolamide, compared with the saline-infused group. Especially, the effect was more potent on the infused (left) side than on the contralateral (right) side. 2. Significant changes in urine volume and urinary electrolytes were also observed in all the aminophylline-treated groups, but no remarkable difference was noticed between the hydrocortisone-infused group and the saline-infused group, nor between the left and right sides. 3. No signicant changes in the clearances of inulin and PAH were in the infused (left) side of all the experimental groups, as compared with the contralateral (right) side. From the above results, it is obvious that hydrocortisone infused into a renal artery exerts diuretic action when administered in combination with acetazolamide, and the mechanism of action rests not on its hemodynamic change for renal blood flow, but on the potentiation of carbonic anhydrase inhibiting action. However, the exact mode of action remains yet to be clarified.

• Wind and Structures
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• v.23 no.2
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• pp.157-169
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• 2016

The structural integrity of tube bundles represents a major concern when dealing with high risk industries, such as nuclear steam generators, where the rupture of a tube or tubes will lead to the undesired mixing of the primary and secondary fluids. Flow-induced vibration is one of the major concerns that could compromise the structural integrity. The vibration is caused by fluid flow excitation. While there are several excitation mechanisms that could contribute to these vibrations, fluidelastic instability is generally regarded as the most severe. When this mechanism prevails, it could cause serious damage to tube arrays in a very short period of time. The tubes are therefore stiffened by means of supports to avoid these vibrations. To accommodate the thermal expansion of the tube, as well as to facilitate the installation of these tube bundles, clearances are allowed between the tubes and their supports. Progressive tube wear and chemical cleaning gradually increases the clearances between the tubes and their supports, which can lead to more frequent and severe tube/support impact and rubbing. These increased impacts can lead to tube damage due to fatigue and/or wear at the support locations. This paper presents simulations of a loosely supported multi-span U-bend tube subjected to turbulence and fluidelastic instability forces. The mathematical model for the loosely-supported tubes and the fluidelastic instability model is presented. The model is then utilized to simulate the nonlinear response of a U-bend tube with flat bar supports subjected to cross-flow. The effect of the support clearance as well as the support offset are investigated. Special attention is given to the tube/support interaction parameters that affect wear, such as impact and normal work rate.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.3
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• pp.414-421
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• 2001

The present study is conducted to investigate the local heat/mass transfer characteristics on the shroud with blade tip clearances. The relative motion between blade and shroud has little influence on the overall heat transfer characteristics, except some local effects. Therefore, the relative motion between the blade and shroud is neglected in this study. A naphthalene sublimation method is employed to determine the detailed local heat/mass transfer coefficients on the surface of the shroud. The tip clearance is changed from 0.66% to 2.85% of the blade chord length. The flow enters the gap between the blade tip and shroud at the pressure side due to the pressure difference. Therefore, the heat/mass transfer characteristics on the shroud are changed significantly from those with endwall. At first, high heat/mass transfer occurs along the profile of blade at the pressure side due to the entrance effect and acceleration of the gap flow. Then, the heat/mass transfer coefficients on the shroud increase along the suction side of the blade because tip leakage vortices are generated and interact with the main flow. The results show that the heat/mass transfer characteristics are changed largely with the gap distance between the tip of turbine blade and the shroud.

• Journal of Pharmaceutical Investigation
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• v.27 no.2
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• pp.109-117
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• 1997

In order to elucidate the effect of phenobarbital (PB) on the nonlinear pharmacokinetic behavior of naproxen (NAP), we compared the dose dependent hepatic intrinsic clearance, biliary excretion and protein binding of NAP in control rats to those in the PB-pretreated rats which were intraperitoneally pretreated with PB sodium (75 mg/kg) once a day for four days. NAP was injected via femoral (1.5 mg/kg) and portal(0.25, 0.5, 1.5, 15 and 30 mg/kg) vein to the control and PB-pretreated rats, respectively. And also, we measured the plasma free fraction of NAP with the equilibrium dialysis method and the biliary excreted total amounts of NAP in both rats. Plasma free fraction of NAP was decreased in lower concentration than $150\;{\mu}g/ml$ of NAP due to PB pretreatment. In higher concentration, however, plasma free fraction was increased. These in vitro results suggest that the total protein concentration was increased but the total binding capacity of NAP to protein was decreased by PB-pretreatment. The total plasma clearance and the hepatic intrinsic clearance of NAP had similar values in both groups, respectively. And, both clearances of NAP were significantly increased by PB-pretreatment. Even though the plasma free fractions of NAP in both groups were constantly remained within the concentration range according to the increase of administration dose, the hepatic intrinsic clearances of NAP were significantly increased in both groups with the increased dose. And, the biliary excreted total amounts of NAP were significantly increased by PB-pretreatment at the lower dose, but decreased at the higher dose. These in vivo results suggest that NAP represents the uncommon nonlinear pharmacokinetic behavior that the hepatic intrinsic clearance was enhanced with the increased dose, and that PB enhances further the hepatic intrinsic clearance of NAP with the increased dose due to its enzyme induction effect.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1337-1340
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• 1995

For the purpose of rational design of air insulation, it is need to experiment with similar to real shape test object and conform the characterisics. But basic distances of air insulation of transmission line, tower, etc. can be acquired from flashover characteristic of rod-rod, rod-plane electrodes. In this paper, before field test of 765kV transmission line for determination of distances of phase to ground insulation, we execute lightning, switching impulse test with test electrod(rod-rod, rod-plane) against clearances of air insulation. Each tests use up-down method and consist of 30 times flashover test. Flashover data treatment program and air correction program following IEC 60-1(1987) standard were completely builted.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.269-274
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• 2000

Frictions and electrical contact voltages of the herringbone-grooved hydrodynamic bearing(HHB) were 9, measured to use in a laser scanner motor. This bearing with varying loads, speeds, oil viscosity, and radial clearances successfully operated up to 28,000rpm and 0.5N. Experimental results under various environments confirmed that this bearing had excellent performance with low friction force, and operated without contact between shaft and sleeve.

• YAKHAK HOEJI
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• v.29 no.3
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• pp.130-143
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• 1985

Bumetanide, when given intravenously in dogs, induced a potent diuresis with an increased amounts of sodium and potassium excreted in urine due to inhibition of reabsorbing them in renal tubule. Furthermore, clearances of osmolar substance and para-aminohippuric acid were increased, but clearace of free water diminished without any change of creatinine clearance. Bumetanide, administered directly into a renal artery, elicited diuresis only in the infused(experimental) kidney by the same mode of action as in the intravenous cases in renal function of the dog. Renal effects of intravenous bumetanide after pretreatment with the small dose of indomethacin (5.0mg/kg) revealed reduction only in clearance of paraaminohippuric acid. However the much dose of indomethacin (5.0mg/kg+5.0mg/kg/hr) or arachidonic acid showed a significant inhibition in the change rates of all renal function by bumetanide. Morover, pretreatment of probenecid also made a marked reduction in renal effects induced by bumetanide. From the above results, it is thought that bumetanide causes diuretic action due to dual mechanism inhibiting reabsorption of electrolytes in loop of Henle and increasing blood flow in kindney, that are provoked through the mediation of prostaglandins.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.215-226
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• 1998

This paper addresses an analytical approach to tolerance and reliability analysis of mechanical systems with uncertainty. Many mechanical systems consist of links and lubricated joints. The mobility method is applied to consider lubrication effects and the clearance vector model is used to stochastically define a mechanism for tolerance and reliability analysis. To show the validity of the proposed method, a four-bar path generator and a slider-crank mechanism are considered. The results obtained by applying the proposed method are compared with those by Monte-Carlo simulation.

• Korean Journal of Computational Design and Engineering
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• v.6 no.1
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• pp.9-16
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• 2001

Electrical discharge machining(EDM) is an important process of machining the injection mold. This paper includes efficient design processes of electrodes for EDM. Based on the solid modeler, electrodes can be created by boolean and offset operations with core/cavity models. The built-in offset operations of the solid modeler may occur unexpected results due to the limitations of the solid modeler. We proposed the multi-step and moving-face offset processes in order to apply the EDM clearances. The proposed design processes are implemented with Unigraphics Vl5 API functions and C language and tested on Windows NT 4.0.

• Biomolecules & Therapeutics
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• v.1 no.2
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• pp.204-210
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• 1993

The distribution and excretion of DWC-751, a new cephalosporin, were examined in rats and mice following a single intravenous administration. DWC-751 in plasma and urine was determined by both HPLC and microbiological assay. The plasma concentration of the drug declined biexponentially. The initial and terminal half lives of the drug were 3.0 and 28.3 min, respectively. Binding of the drug to plasma proteins was 42.3%. The distribution volume at steacly-state ($Vd_{ss}$) was only 0.341 ι/kg, which is well correlated with the low n-octanol/water partition coefficient of the drug ($K_{o/w{\cong}0$) Actually, the drug was distributed to liver, kidney and lung with very low organ/plasma concentration ratio. The drug, was excreted mainly via renal excretion, i.e., the total($CL_T$) and apparent renal($CL_{R}$) clearances of the drug were 10.8 and 7.5 ml/min/kg, respectively.