• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.10
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• pp.500-505
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• 2002

In this paper, fluorescent discharge type ozonizer has been designed and manufactured. Ozone discharge and generation characteristics have been investigated in accordance with a sort of internal electrodes, output voltage of power supply, air flow rate and discharge power. Air has been used as the supplied gas of the ozonizer In this paper, when disuse fluorescent lamp was used as an internal electrode. Air flow rate was varied from 2[1/min] to 10[1/min]. The maximum ozone concentration and yield were 3495[ppm] and 23.4[g/kWh] respectively at 2[1/min] air flow rate and 35.2[W] input power. Illumination was appeared as 5[lx] within 15[cm] from external electrode. Whorl fluorescent discharge type ozonizer was used, air flow rate was also varied from 2[1/min] to 10[1/min]. At this moment, the maximum ozone concentration and yield were 2824[ppm] and 21.7[g/kWh] respectively at 2[1/min] air flow rate and 30.5[W] input power. Illumination was also appeared as 5[lx] within 15[cm] from external electrode like used fluorescent lamp.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.271-278
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• 2020

The investigation into a full-scale 27 m high, by 6 m wide, thermosyphon loop. The simulation model is based on a one-dimensional axially-symmetrical control volume approach, where the loop is divided into a series of discreet control volumes. The three conservation equations, namely, mass, momentum and energy, were applied to these control volumes and solved with an explicit numerical method. The flow is assumed to be quasi-static, implying that the mass-flow rate changes over time. However, at any instant in time the mass-flow rate is constant around the loop. The boussinesq approximation was invoked, and a reasonable correlation between the experimental and theoretical results was obtained. Experimental results are presented and the flow regimes of the working fluid inside the loop identified. The results indicate that a series of such thermosyphon loops can be used as a cavity cooling system and that the one-dimensional theoretical model can predict the internal temperature and mass-flow rate of the thermosyphon loop.

• Nuclear Engineering and Technology
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• v.45 no.2
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• pp.257-264
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• 2013

In Canada Deuterium Uranium (CANDU)-type nuclear power plants, the reactor is composed of 380 fuel channels and refueling is performed on one or two channels per day. At the time of refueling, the fluid force of the cooling water inside the channel is exploited. New fuel added upstream of the fuel channel is moved downstream by the fluid force of the cooling water, and the used fuel is pushed out. Through this process, refueling is completed. Among the 380 fuel channels, outer rows 1 and 2 (called the FARE channel) make the process of using only the internal fluid force impossible because of the low flow rate of the channel cooling water. Therefore, a Flow Assist Ram Extension (FARE) tool, a refueling aid, is used to refuel these channels in order to compensate for the insufficient fluid force. The FARE tool causes flow resistance, thus allowing the fuel to be moved down with the flow of cooling water. Although the existing FARE tool can perform refueling in Korean plants, the coolant flow rate is reduced to below 80% of the normal flow for some time during refueling. A Flow rate below 80% of the normal flow cause low flow rate alarm signal in the plant operation. A flow rate below 80% of the normal flow may cause difficulties in the plant operation because of the increase in the coolant temperature of the channel. A new and improved FARE tool is needed to address the limitations of the existing FARE tool. In this study, we identified the cause of the low flow phenomena of the existing FARE tool. A new and improved FARE tool has been designed and manufactured. The improved FARE tool has been tested many times using laboratory test apparatus and was redesigned until satisfactory results were obtained. In order to confirm the performance of the improved FARE tool in a real plant, the final design FARE tool was tested at Wolsong Nuclear Power Plant Unit 2. The test was carried out successfully and the low flow rate alarm signal was eliminated during refueling. Several additional improved FARE tools have been manufactured. These improved FARE tools are currently being used for Korean CANDU plant refueling.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.6
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• pp.461-470
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• 2003

The purpose of this study is to investigate the performance of a transcritical cycle for hot water heating using $CO_2$ as a working fluid. Some of the main parameters that affect the practical performance of the $CO_2$ system are discussed; the performance on the variation of refrigerant charge, changes in flow conditions of secondary fluids, and that with or without internal heat exchanger, The experimental results show that the optimum charge is approximately the same for various mass flow rates of the secondary fluid at gas cooler. The experimental results on the effect of secondary fluids are in general agreement with the experimental results of transcritical cycle in the open literature and show similar trend for conventional subcritical vapor compression cycles. The heat exchanger effectiveness increases with an increase of the heat exchange area of the internal heat exchanger regardless of the mass flow rate at the gas cooler.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.12
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• pp.4053-4061
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• 1996

Internal flow characteristics within Y-jet atomizers and the local drop size distribution and cross-sectional averaged drop size at the outside were investigated with the liquid and air injection pressures, mixing port length of atomizers, and the liquid properties taken as parameters. To examine the effect of the liquid viscosity, glycerin-water mixtures were used in this study. The liquid viscosity plays only a minor role in determining the internal flow pattern and the spatial distribution shape of drops, but the drop sizes themselves generally increase with increasing of the liquid viscosity. An empirical correlation for the liquid discharge coefficient at the liquid port was deduced from the experimental results; the liquid discharge coefficient strongly depends on the liquid flow area at the mixing point which is proportional to the local volumetric quality(.betha.$_{Y}$), and the volumetric quality was included in the correlation. Regardless of the value of the liquid viscosity, the compressible flow through the gas port was well represented by the polytropic expansion process(k=1.2), and the mixing point pressure could be simply correlated to the aspect ratio( $l_{m}$/ $d_{m}$) of the mixing port and the air/liquid mass flow rate ratio( $W_{g}$/ $W_{f}$) as reported in the previous study.udy.udy.y.

• Tuberculosis and Respiratory Diseases
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• v.86 no.1
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• pp.65-66
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• 2023

• Journal of Power System Engineering
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• v.20 no.1
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• pp.5-10
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• 2016

Swing check valve is opened when the flow direction is forward, when the flow is reversed, the valve is automatically closed by back pressure. In this study, the internal flow field analysis of the valve was conducted by Fluent. The working fluid used in the study, using liquefied methane $-165^{\circ}C$ (CH4) and velocity field, pressure field, pressure drop coefficient were simulated by varying separately the opening divergence into four intervals from 0 to 100%. The approximate research result are as follow : When the opening divergence is smaller, it appears high pressure on the upstream side, this value is relaxed when the opening divergence is large. Flow rate coefficient of the valve shows a larger value as the degree of opening becomes larger, confirming that the check valve used in the study is in the effective flow rate counting range.

• Journal of Chest Surgery
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• v.32 no.8
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• pp.709-714
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• 1999

Background: When internal thoracic artery (ITA) and saphenous vein graft are anastomosed to the same coronary artery, the patency rate of the internal thoracic artery graft with relatively narrow diameter may be decreased owing to competition of pressure and flow rate. We evaluate the clinical outcome and the patency of the ITA graft in patients undergoing dual grafting to the same coronary artery. Material and Method: In 14 patients with the ITA graft having relatively low flow, the ITA and saphenous vein graft were anastomosed to the same coronary artery. During the mean follow-up period of 33.5 months, coronary angiography was performed in 6 patients who complained of recurrent angina, needed confirmation of graft flow, or showed postoperative Q wave. Result: In all 6 patients, the ITA and saphenous vein grafts were patent without stenosis or obstruction. Two patients showed good flow in both grafts, 2 showed competitive flow in the ITA graft, and the remaining 2 showed poor flow in the ITA graft. Conclusion: Early operative closure When saphenous vein grafting was added to the same coronary artery that the internal thoracic artery was anastomosed to, the perfusion to the coronary artery was satisfied and the dual grafting did not affect the short-term and mid-term patency rate of the ITA.

• Journal of Oral Medicine and Pain
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• v.46 no.4
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• pp.109-116
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• 2021

Purpose: Xerostomia is subjective feeling of dry mouth. It is complicated and multifactorial, which burdens clinicians in diagnosis and treatment of the problem. The goal of this study was to discuss the clinical importance of salivary flow rate, pH and subjective symptoms for evaluating oral dryness among young healthy male subjects. Methods: Thirty male participants were recruited in this study (mean age±standard deviation of 25.70±1.84). All participants completed 'Xerostomia Inventory' to measure subjective oral dryness scores. Unstimulated saliva and stimulated saliva were collected from each participant twice a day at 12:00 pm and 5:00 pm, using spitting method. Salivary flow rates and pH were measured immediately after collection. Relationship between objective and subjective measurements were analyzed. Results: There were excellent intra-examiner reliability for salivary flow rate and pH and good internal consistency for Xerostomia Inventory. Objective measurements and subjective symptoms did not exhibit positive association. Salivary flow rate in unstimulated and stimulated condition showed positive association and also for salivary pH. Stimulated salivary flow rate also presented positive correlation with stimulated salivary pH. Conclusions: Comprehensive assessment of objective measurements and subjective symptoms may be complimentary for assessing oral dryness, which would assist in implementing early interventions to improve patient's quality of life.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.2
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• pp.245-256
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• 2002

This studt was investigated to prove the effect of SPBST on the hypertension, the thrombosis and the brain damage. The results were as follows; 1. SPBST affected the htpertension as adepressant, but insignificant. 2. SPBST decreased significantly dopamine, aldosterone but ineffective on the epinephrine, norepinephrine and renin activity. 3. SPBST increased the NO product but insignificant. 4. SPBST had a death suppression effect by 50% in pulmonary thrombosis inducement experiment and activated slightly on the fibrinolytic activity. 5. SPBST suppressed significantly platelet diminution and prolonged insignificantly PT and APTT. 6. On the measure of the blood flow rate induced by the thrombus, in vivo SPBST accelerated the blood flow rate, in vitro insignificant. 7. SPBST had no toxicity on the PC12 cell and B103 cell induced by amyloid β protein (-35) and a protective effect, in proportion to the density. 8. SPBST decreased significantly coma duration time in a Infatal dose of KCN and showed 50% of survival rate in a fatal dose. 9. SPBST decreased significantly ischemic area and edema incited by the MCA blood flow block. These results indicate that SPBST can be used in hypertension, the thrombosis, the brain damage, the ischemic cerebral infarction and the acute stage of the brain damage. Further study will be needed about the functional mechanism and etc.