• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1113-1120
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• 1999

Leakage vortices fonned near the blade tip cause an increase of total pressure loss near the casing endwall region and as a result, the efficiency of rotor decreases. The reduction of rotor efficiency is related to the size of tip clearance. In this study, the three-dimensional flow fields in an axial flow rotor were calculated with varying tip clearance under various flow rates, and the numerical results were compared with experimental ones. The effects of tip clearance and the of attack on the leakage vortex and overall performance, and the los9 distributions were investigated through numerical calculations. In this study, tip leakage flow rate and total pressure loss due to the tip clearance were evaluated using numerical results and approximate equations were presented to evaluate the reduction of rotor efficiency due to the tip leakage flow.

• The Korean Journal of Nuclear Medicine
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• v.4 no.2
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• pp.67-71
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• 1970

Fourteen patients with typhoid fever were studied by scanning and clearance-rate measurements of subcritical dose colloidal radiogold($^{198}Au$). Mild to moderate enlargement of the liver and spleen was noted in 78.6 and 64.3 per cent of patients, respectively; and splenic and spinal bone-marrow uptake was seen in 78.6 and 57.1 per cent of cases, respectively. Typically, these scan changes occurred concomitantly (57.1%) and are considered to represent increased phagocytic activity of the RE cells which is characteristic of typhoid fever. The half clearance-time was significantly shortened during the first 10-day period of the illness indicating an increas in the hepatic blood in the early phase of typhoid infection. Hepatomegaly, splenomegaly and extrahepatic uptakes along with an accelerated (or later a normal) clearance time are characteristic of typhoid fever.

• Fisheries and Aquatic Sciences
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• v.5 no.3
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• pp.183-190
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• 2002

To determine the effect of body size on the clearance rate and ingestion rate of small intertidal bivalves, Glauconome chinensis, feeding experiments were conducted on individuals of 12 different size classes, from 4 to 16 mm in shell length. Relationships between morphological parameters were also determined. The clearance and ingestion rates of G. chinensis responded similarly to their body size, ranging from 1.3 to 28.2 mL/hr/ind. and from 24.0 to 458.5, ${\mu}gC/hr/ind$., respectively. Both rates increased significantly (p<0.001) as shell length increased from 4 to 9 mm, although neither rate changed significantly when shell length was in the range from 12 to 16 mm. The weight-specific clearance rate $(CR_w)$ and ingestion rate $(IR_w)$ decreased with increasing body size, with values from 1.0 to 3.1 L/hr/g and from 17.9 to 51.3 mgC/hr/g, respectively. The $CR_w$ of G. chinensis was intermediate compared to those of larger bivalve species. The clearance rate (CR) relative to flesh dry weight (FDW) of G. chinensis were fitted well to the power function: $CR=0.43\times(FDW)^{0.71}\;(r^2=0.89)$. The exponent of fitting equation (0.71) of G. chinensis was higher than those of Mytilus edulis (Walne, 1972), Crassostrea gigas (Walne, 1972), and Placopecten magellanicus (MacDonald and Thompson, 1986).

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2001.12a
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• pp.130-130
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• 2001

• Tribology and Lubricants
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• v.14 no.4
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• pp.15-22
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• 1998

Recently, the importance of variable displacement piston pump is increasing in industrial world. Especially, most consumers require various range of pressures and flow rates. Pressure compensator is a system controlling flow rate in piston pump at low cost and, therefore, satisfies the need of consumers. However, the system has serious problems, such as response and leakage. The response and leakage are affected by clearance between actuator piston and cylinder, roughness of surface, and spool overlap. In this paper, these effects are investigated experimentally, and optimal clearance and chamfer is obtained. While diameter of cylinder is fixed and diameter of actuator piston is changed in this experiment, response and leakage are measured. Also parameters such as roughness and processing accuracy are changed for piston of fixed clearance. Experimental setup modelled into several parts of actuator piston, cylinder, spool, and swash plate. Input pressure is changed by function generator and proportional valve. The result of this experiment shows that leakage increases very much in proportion to the increase of clearance, and especially leakage occurs enormously when clearance is more than 0.002. The response is not good because as clearance increases leakage increases and as clearance decreases viscous damping effect increases. Accordingly, it is found out that optimal clearance range exists for tile response, within about 0.0012∼0.0014, at this time. Futhermore, the better roughness and geometrical accuracy of actuator piston are, the smaller are leakage and friction. The paper informs that response and leakage are influenced by and geometrical accuracy of actuator piston, roughness of surface, and the clearance between actuator piston and cylinder, and that optimal design of actuator piston in the pressure compensator is possible.

• The Korean Journal of Physiology
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• v.11 no.1
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• pp.37-44
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• 1977

In the previous study of the release, excretion, and plasma concentration of aldosterone in normal Koreans, the author found that urinary aldosterone excretion and aldosterone secretion rate of the Korean who usually take high amount of salt are significantly lower, in compared to Americans, although the plasma concentration is only tended to be low. The control of plasma aldosterone level depends on the secretion rate and the metabolic clearance of the hormone. In this experiments, the metabolic clearance rate of aldosterone was determined in normotensive korean and the effects of adrenal stimulations on the rates were also studied in the same subjects. The metabolic clearance rate of the normal Korean was not significantly different from those of the American, and shown a little increase in response to sodium restriction. These results indicate that the decrease in secretion rate rather than the increase in metabolic clearance Tate is the major factor maintaining lower plasma aldosterone level. After furosemide diuresis, on the contrary, the removal of aldosterone showed significant the decrease despite slight increase of secretion rate. This suggest that the reduction in metabolic clearance rate of the hormone during volume depletion found to be major cause of high plasma concentration. Additional potassium supply produced detectable decrease of metabolic clearance rate, but the changes were smaller than that of secretion rate, which suggested that the higher secretion rate could account for elevated plasma concentration of aldosterone rather than metabolic clearance. Above results also support author's previous evidences that the normal Korean who already adapted to a high sodium diet have ability to produce adequate aldosterone activity without producing detectable changes on the metabolic clearance rate under the condition of sodium restriction with approp riate potassium intake.

• Fisheries and Aquatic Sciences
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• v.12 no.4
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• pp.331-338
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• 2009

This study presents physiological rates of respiration and excretion, clearance rate, and assimilation efficiency of the ark shell Scapharca broughtonii, determined during 2007 from specimens collected in Gamak Bay on the south coast of Korea. Physiological parameters were measured monthly under static, laboratory controlled conditions with ambient conditions, and measurements were performed seasonally in order to estimate scope for growth and its probable sources of variation. Temperature directly influenced respiration and excretion. Clearance rates showed a tendency to be low during May-August, which is a period of gametogenesis. Assimilation efficiency was not significantly different seasonally and was independent of the concentration of chlorophyll a. The scope for growth was negative during high-temperature months (July-August), reflecting the high temperature and low clearance rate, and had its highest positive values during spring and autumn. The energy budget or growth potential of bivalves has been applied to other economically important species. Data on the physiological parameters and scope for growth of S. broughtonii obtained in this study will be used to assess the carrying capacity for ark shell cultivation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1106-1112
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• 1999

Substantial losses behind axial flow rotor are generated by the wake, various vortices in the hub region and the tip leakage vortex in the tip region. Particularly, the leakage vortex formed near blade tip is one of the main causes of the reduction of performance, generation of noise and aerodynamic vibration in downstream. In this study, the three-dimensional flow fields in an axial flow rotor were calculated with varying tip clearance under various flow rates, and the numerical results were compared with experimental ones. The numerical technique was based on SIMPLE algorithm using standard $k-{\varepsilon}$ model(WFM) and Launder & Sharma's Low Reynolds Number $k-{\varepsilon}$ model(LRN). Through calculations, the effects of tip clearance and attack angle on the 3-dimensional flow fileds behind a rotor and leakage flow/vortex were investigated. The presence of tip leakage vortex, loci of vortex center and its behavior behind the rotor for various tip clearances and attack angles was described well by calculation.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.3
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• pp.260-264
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• 1997

This study was conducted with adult cockerels to determine whether dietary RNA affects feed intake and renal weight and function, and if the responses are similar to dietary adenine. Chickens were ad libitum fed a RNA diet (100 g/kg) or an adenine diet (9.1 g/kg) for 14 d and catheterized in right jugular vein, hepatic portal vein and both urethers, and saline together with para-amino hippuric acid and sodium thiosulfate was continuously infused into them to evaluate renal functions. Dietary RNA reduced feed intake and body weight, and dietary adenine increased kidney weight expressed as a proportion of body weight (P < 0.05). Feed intake and body weight on the adenine diet and kidney weight on the RNA diet showed similar though non significant tendencies. No calculi were detected in the kidney in chickens fed either the RNA or adenine diets. Plasma inorganic phosphate (IP), Ca and 1,25 $(OH)_2$ vitamin $D_3$ concentrations were increased by dietary RNA and adenine, although the increases of IP and Ca in adenine-fed chickens were not significant. Uric acid and urea concentrations in the blood plasma were unaffected by dietary RNA or adenine. Both dietary RNA and adenine increased renal blood flow rates 3.5-3.7 fold, renal plasma flow rates 3.4-3.7 fold and glomerular filtration rates (GFR) 2.9-3.0 fold (p < 0.01). Clearance of urea, IP and Ca were also enhanced by dietary RNA, but not by dietary adenine. However, neither RNA nor adenine affected uric acid clearance. Only IP clearance was significantly augmented at the glomerular level by dietary RNA (p < 0.05). Glomerular filtration of uric acid, urea, IP and Ca and reabsorption of urea, IP and Ca at the renal tubule were increased by dietary RNA and adenine (p < 0.05), whereas tubular secretion of uric acid was decreased by both dietary treatments. It is concluded that dietary adenine is effective in changing renal function and P and Ca metabolism in chickens.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.24 no.4
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• pp.366-376
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• 2021

Purpose: There is no consensus regarding adjuvant therapies following Kasai portoenterostomy (KP) for biliary atresia (BA). This study aimed to analyze the effect of extended perioperative intravenous antibiotics (PI-Abx) and adjuvant corticosteroid on cholangitis and jaundice clearance rates in the 3 years post-KP in children with BA. Methods: Data of patients who underwent KP between 1999-2018 at a single center were retrospectively analyzed. Group A (1999-2010) received PI-Abx for 5 days, Group B (2010-2012) received PI-Abx for 5 days plus low-dose prednisolone (2 mg/kg), and Group C (2012-2017) received PI-Abx for 14 days plus high-dose prednisolone (5 mg/kg). Results: Fifty-four patients were included with groups A, B, and C comprising 25, 9, and 20 patients, respectively. The number of episodes of cholangitis was 1.0, 1.6, and 1.3 per patient (p=NS) within the first year and 1.8, 2.3, and 1.7 (p=NS) over 3 years in Groups A, B, and C, respectively. The jaundice clearance rate at 6 months was 52%, 78%, and 50% (p=NS), and the 3-year native liver survival (NLS) rate was 76%, 100%, and 80% (p=NS) in Groups A, B, and C, respectively. A near-significant association was observed between the incidence of cholangitis within the first year and decompensated liver cirrhosis/death at 3 years post KP (p=0.09). Persistence of jaundice at 6 months was significantly associated with decompensated cirrhosis/death at 3 years (p<0.001). Conclusion: The extended duration of PI-Abx and adjuvant corticosteroids was not associated with improved rates of cholangitis, jaundice clearance, or NLS in patients with BA.