• 한국해양학회지
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• v.30 no.5
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• pp.458-466
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• 1995

To clarify the role of protozooplankton in the microbial food web of Inchon coastal ecosystem, the grazing capacities and growth rates of heterotrophic flagellated (HFL) and ciliates were investigated. We measured the growth rates of bacteria, HFL, autotrophic flagellated (AFL) and ciliates using reverse flow (RF) filter set and obtained the clearance rates and ingestion rates of HFL and dilates by fluorescent labelled bacteria (FLB) method and isolation culture method from natural seawater of Inchon coastal area. The standing crops of bacteria, HFL, AFL and ciliates in this study area were 0.7∼1.5${\times}$10/SUP 6/ cells$.$ml/SUP -1/ 1,680∼2,180 cells$.$ml/SUP -1/, 1,090∼2,180 cells$.$ml, and 3,600∼5,700 cells$.$l/SUP -1/, respectively. The mean growth rates of bacteria, HFL, AFL and ciliates were 0.039 h/SUP -1/, 0.032∼0.033h/SUP -1/, 0.015∼ 0.025h/SUP -1/and 0.021h/SUP -1/, respectively. The growth rates of protozooplankton of Inchon coastal waters were relatively low. Mean grazing rate of HFL, AFL and ciliates were0.039 h/SUP -1/, 0.032∼0.033h/SUP -1/,0.015∼ 0.025h/SUP -1/and 0.021h/SUP -1/, respectively. The growth rates of protozooplankton of Inchon coastal waters were relatively low. Mean grazing rate of HFL on bacteria was 0.055h/SUP -1/. Mean grazing rates of ciliates on HFL was relatively high of 0.057 h/SUP -1/, while the grazing rate of ciliates on AFL was low of 0.019h/SUP -1/. The clearance rates and ingestion rates of HFL on bacteria were 3.6∼61.8nl$.$HFL$.$h/SUP -1/ and 6∼52 BAC. HFL$.$h/SUP -1/ respectively. FLB grazing experiment showed low values, while natural bacteria experiment showed high value meaning high grazing pressure on total bacteria. The clearance rates and ingestion rates of Tintinnopsis sp., dominant ciliates in Inchon coastal waters, were 3.2∼4.6 ul$.$CIL/SUP -1/$.$h/SUP -1/ and 5∼6 cells$.$CIL/SUP -1/$.$h/SUP -1/ respectively, showing higher values in the high tide than low tide. The ingestion rates of ciliates implies that ciliate took up 17∼20% of total nanoflagellates of Inchon coastal waters.

• The Korean Journal of Physiology
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• v.19 no.1
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• pp.35-48
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• 1985

One of most frequently used anesthetic agents is barbiturate derivatives. Pentobarbital or thiopental sodium have been used most frequently in the laboratory or clinical practice. There have been reports on the renal effects of barbiturate anesthesia in human and laboartory animals. Renal effects of thiopental sodium anesthesia, however, are still controversial. One of the discrepancies may be derived from the doses used. It has been reported that subanesthetic small dose of thiopental sodium influences the renal function directly. To clarify possible central effects of very small amounts of thiopental sodium on the renal function, experiments have been done in conscious rabbits. Thiopental sodium was infused into the lateral cerebroventricle for 10 minutes. Intracerebroventricular thiopental sodium induced increased urinary volume, glomerular filtration rate and renal plasma flow by doses of $0.1{\sim}1.0\;mg/10 min/rabbit$. Filtration fractions were not changed. Sodium, chloride and potassium excretions were increased by 0.065 mg/10 min/rabbit of thiopental sodium without significant changes of renal hemodynamics. Higher doses of thiopental sodium $(0.1{\sim}1.0\;mg/10 min/rabbit)$ induced greater increases of electrolytes excretion and renal hemodynamics. Free water clearance was not changed by thiopental sodium, but the fractional excretion of free water showed a tendency of decrease. Fractional excretion of sodium was increased by doses of 0.065 to 1.0 mg of thiopental sodium . Highly significant correlation between the changes of glomerular filtration rate and the changes of sodium excretion were found in the higher doses. Plasma renin concentration (activity) was not changed by the centrally administered thiopental sodium. Intravenous thiopental sodium, 1.0 mg/rabbit, induced no changes of renal function in conscious rabbit. These data suggest that intracerebroyentricular thiopental sodium can increase urinary sodium excretion directly by inhibition of sodium reabsorption in the renal tubules and/or indirectly by increasing the renal hemodynamics.

• Journal of Biosystems Engineering
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• v.10 no.1
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• pp.13-23
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• 1985

Spraying method from the paddy-field levee is known to give insufficient penetration of the spray droplets to the rice stem of the densely grown plants, which is generally encountered at the last stage of rice growth. This study was intended to investigate the spraying system to solve this existing problem. As an approach, it was attempted to develop the boom-with-nozzle, between-the-row application system. Several types of nozzles and their different arrangements in the boom were tested in the field to measure the penetration-reaching distance and the uniformity of spray droplet distribution. The results of the study are summarized as follows: 1. Field experiments by the spraying method from the paddy-field levee showed to have practically no penetration of the spray droplets to the portion of the plant stem with the normal flow volume generally applied and thus need for improving present spraying method. 2. It was found that, considering both the uniformity of the spray droplet distribution and performance rate, the most efficient type of nozzle in the between-the-row boom-type spraying system was one that has core-insert hollow-cone with some clearance between the cone and tip. 3. When tested by applying the spraying method of between-the-row, the nozzle pressure did not affect the uniformity of spray droplet distribution. However, the nozzle pressure had a positive effect on the penetrating-reaching distance of the facing side of the rice stem and did not affect much on that of the opposite face of the stem. It was also found that the maximum pressure to affect the penetration-reaching distance was about $10kg/cm^2$. 4. The uniformity of the spray droplet distribution in the between-the-row system was greatly affected by the height and orientation of the nozzles in the boom. Based on experimental work for the different type of the boom-with-nozzle arrangements, it is recommended that the position of nozzle is set at about 0.45 m above the ground and two nozzles in the boom are oriented to be faced with each other with some angle such that the droplet stream from the nozzle would not directly face with each other.

• Tribology and Lubricants
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• v.28 no.1
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• pp.12-18
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• 2012

This application study of a swash-plate type axial piston pump was concerned about the lubrication characteristics between cylinder barrel and valve plate which are the main rotating body and its opposite sliding part respectively. A computer simulation was implemented to assess bearing and sealing functions of the fluid film between cylinder barrel and valve plate. A numerical algorithm was developed to facilitate simultaneous calculations of dynamic cylinder pressure, 3 degree-of-freedom barrel motions considering inertia effect, and fluid film pressure assuming full fluid film lubrication regime. Central clearance, tilt angle, and azimuth angle of the rotating body were calculated for each time step. Surface waviness was found to be an influential factor due to the small fluid film thickness which can appear in flat land bearings. Five surface lays which can form on the lubrication surface in accordance with machining process were defined and analyzed using the simulation tool. Oil leakage flow and frictional torque in the fluid film between cylinder barrel and valve plate were also calculated to discuss in the viewpoint of energy loss. The simulation results showed that in actual sliding conditions proper surface non-flatness can make a positive effect on the energy efficiency and reliability of the thrust bearing.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.33-41
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• 2014

In a supersonic turbine, A rotor overlap technique reduced the chance of chocking in the rotor passage, and made the design pressure ratio satisfied. However, the technique also made additional losses, like a pumping loss, expansion loss, etc. Therefore, an approximate optimization technique was appled to find the optimal shape of overlap which maximizes the improvement of the turbine performance. The design variables were shape factors of a rotor overlap. An optimal design for rotor overlap reduces leakage mass flow rate at tip clearance by about 50% and increases about 4% of total-static efficiency compared with the base model. It was found that the most effective design variable is the tip overlap and that the hub overlap size is the lowest.

• Journal of Acupuncture Research
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• v.18 no.3
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• pp.114-122
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• 2001

Objective : The present study was carried out to determine if Juglandis Semen Aquacupuncture(JSA) exerts beneficial effect against the urine concentrating defect induced by glycerol injection in rabbits. Methods : In order to test the effect of JSA, rabbits were acupunctured with $0.5m{\ell}$ of 1%JSA for 7days at both sides of $Sh{\grave{e}}ns{\bar{u}}$(BL23) before the glycerol injection. The other animals were pretreated with an equal volume of saline instead of JSA. Results : The urine flow was reduced, but the urine osmolality was significantly lower than the basal period in glycerol-injected animals, indicating that glycerol causes the urine concentrating defect. The fractional excretion of Na and K was increased in glycerol-treated animals. The Free-water clearance and fractional water excretion(V/GFR) were increased in animals treated with glycerol. Conclusion : These results indicate that glycerol injection resulted an impairment in the urine concentrating ability in rabbits. Such changes were prevented by JSA. JSA may be used as a method to treat and prevent glycerol-induced acute renal failure.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.5 no.2
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• pp.71-78
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• 2019

Nuclear imaging is one of the most powerful measures for non-invasive diagnosis of myocardial vascular disease. Radionuclide such as ¹³N, ¹⁵O, ²⁰¹Tl and ⁸²Rb is used for the measurement of cardiac blood flow. ¹³N, ¹⁵O and ²⁰¹Tl are produced in cyclotrons while ⁸²Rb is obtained from generator. Rubidium (Rb), an alkali ion, behaves biologically like potassium, and accumulates in myocardial tissue. Rb has rapid blood clearance profile which allows the use of ⁸²Rb with a short physical half-life of 75 s for non-invasive evaluation of regional myocardial perfusion. There are several advantages of ⁸²Rb over other radioisotopes. An ultra-short half-life significantly reduces the exposure of patients to radiation and allows to repeat injections for studying the effects of medical intervention. As a positron emitter, ⁸²Rb allows positron emission tomography (PET) imaging which have shown superior diagnostic performances. ⁸²Rb can be produced from generator by decay of its parent ⁸²Sr. However, the preparation of ⁸²Sr is difficult, because appropriate purity is required to meet the specification of the product. Recently reported procedure from ARRONAX research institute showed that a Chelex-100 resin is sufficient for this purpose and additional column is not necessary. Whereas Brookhaven National Laboratory (BNL) procedure contains three ion exchange resin separation, including Chelex-100 resin. Currently, since ⁸²Sr production site is non-existent in Korea, Korea Atomic Energy Research Institute (KAERI) has plan to produce ⁸²Sr within specifications. We compared ⁸²Sr purification procedures reported from ARRONAX and BNL to investigate the most suitable procedure for our conditions.

• Journal of Pharmaceutical Investigation
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• v.7 no.1_4
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• pp.38-50
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• 1977

A study on the mechanism of biliary and urinary excretion of chloramphenicol has been performed in the dog. 1) Chloramphenicol administered intravenously to dogs with ligated renal pedicle, readily appeared in bile greater than in plasma. 6.9% of a 50mg /kg i. v. dose of chloramphenicol were excreted into bile within 100 minutes. During the same periods of above experiment, the bile/plasma concentration ratios(B/P ratios) were 46 to 87. 2) Chloramphenicol injected into the vein of dog was rapidly excreted into urine. 18% of the administered dose were excreted into urine within 70 minutes. In the same periods of this experiment, Ccm/Ccr ratios were greater than 1.0 in most cases. 3) In experiment of simultaneous measurement of biliary and urinary excretion of chloramphenicol, Ccm/Ccr ratios were less than 1.0 and B/P ratios were 50 to 52. 4) In experiment measured simultaneously biliary and urinary excretion both Ccm/Ccr and $C^Hcm$(hepatic clearance) were significantly declined by probenecid, but not affected by 2,4-DNP and aminophylline although 2,4-DNP increased only bile flow and aminophylline both bile and urine volume. 5) Ccm/Ccr and $C^Hcm$ were increased in proportion to increment of plasma concentration ranging from 3.3 to 30 mg% of chloramphenicol. But when plasma concentration were increased to 70mg %, Ccm/Ccr were not increased and $C_Hcm$ were reduced about 30% in comparison with values obtajned at 30mg% of chloramphenicol. 6) Free/Bound(free to bouid from) ratios ranging from 1.0 to 90.0mg% of chloramphenicol were 76.2+3.72% $(mean{\pm}S.E.)$ Above results suggest that chloramphenicol is excreted into bile by a process of active trasport, that excretion of chloramphenicol into urine was made up with dual process, reabsorption and secretion, and that renal secretion was attained by active trasport process although renal reabsorption process could not understand.

• Tribology and Lubricants
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• v.34 no.4
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• pp.138-145
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• 2018

Elliptical bearings are widely used for large steam turbines owing to their excellent load carrying capacity and good dynamic stability. Power loss in bearings is an extremely important parameter, especially for high turbine capacities. Optimization of operation conditions and design variables such as bearing clearance and bearing length can reduce the power loss in elliptical bearings. Although changes in the oil supply method have served to increase the efficiency of the tilting pad journal bearing, it has not explicitly improved elliptical bearings. In this study, we verify the static characteristics of an elliptical bearing by changing the direction of oil supply. We evaluate the bearing power loss and bearing metal temperature, and compare the bearing performance and reliability in different test cases. The direction of oil supply is $90^{\circ}$ (9 o'clock) and $270^{\circ}$ (3 o'clock) when the rotor rotates in a counterclockwise direction. We use an elliptical bearing with an inner diameter and active length of 220.30 and 110.00 mm, respectively. Bearing power loss and bearing metal temperatures are measured and evaluated by rotor rotational speed, oil flow rate, and bearing load. The results reveal a 20 reduction in the power loss when the direction of oil supply is 90. Furthermore, the oil film on the upper part of the bearing has a high temperature when the direction of oil supply is $90^{\circ}$. In contrast, when the direction of oil supply is $270^{\circ}$, the oil film on the upper part of the bearing is relatively cold.

• The Korean Journal of Pharmacology
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• v.12 no.2 s.20
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• pp.43-49
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• 1976

The facts that $PGE_2$ produced diuresis in the rabbit when given into a lateral ventricle of the brain and that $PGF_{2{\alpha}}$ is abundantly found in the brain prompted us to investigate the effects of $PGF_{2{\alpha}}$ introduced directly into the ventricle on the renal function. $PGF_{2{\alpha}}$ given intraventriculary in doses of $10{\mu}g\;and\;100{\mu}g$ elicited prompt diuresis, 10-fold increase of sodium excretion and two-fold increment of potassium excretion. Free water reabsorption also increased along with the increased osmolar clearance. Neither renal plasma flow nor glomerular filtration rate did change significantly. This, along with the fact that the percentage of reabsorbed sodium filtered decreased from 99.5 to 93.9, indicates the tubular site of the diuretic and natriuretic action. Atropine pretreatment did not influence the renal effects of intraventricular $PGF_{2{\alpha}}$. Intravenously administered $PGF_{2{\alpha}}$ in doses of 30 to $100{\mu}g$ did not produce any significant change in renal function. Intraventricular $PGF_{2{\alpha}}$ had no effect on the systemic blood pressure, whereas intravenous administration brought about a transient hypotension. These observations suggest that $PGF_{2{\alpha}}$ induces diuresis and natriuresis via central mechanism, that the site of the action resides in renal tubules, and that the reabsorption of sodium is inhibited in the proximal tubule, possibly through mediation of certain humoral agent. Overall, it is suggested that $PGF_{2{\alpha}}$ might play a roll in regulating renal function through the center.