• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.3
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• pp.255-262
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• 2014

To investigate the effect of oil on evaporation heat transfer of plate heat exchanger, evaporation heat transfer experiment was carried out using experimental apparatus for micro gear pumped R134a-oil circulation. By varying oil circulation rate of POE oil from 0 to 5%, evaporation heat transfer performance of plate heat exchanger was investigated. As OCR(Oil Circulation Ratio) increases, the evaporation heat transfer coefficient of R134a decreases and pressure drop increases. When the evaporating temperature is $30^{\circ}C$ and the refrigerant mass flow rate is 80 g/s, evaporation heat transfer rate decreases by 10 % and pressure drop increases by 10% at 2% of OCR condition.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1446-1453
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• 2021

In the past, several experimental investigations aiming at characterizing the natural circulation (NC) behavior in test facilities were carried out. They showed a variety of flow patterns characterized by an inverted U-shape of the NC flow curve versus primary mass inventory. On the other hand, attempts to reproduce such curves using thermal-hydraulic system codes, showed 10-30% differences between the measured and calculated NC mass flow rate. Actually, the used computer codes are generally based upon nodalization using single U-tube representation. Such model may not allow getting accurate simulation of most of the NC phenomena occurring during such tests (like flow redistribution and flow reversal in some SG U-tubes). Simulations based on multi-U-tubes model, showed better agreement with the overall behavior, but remain unable to predict NC phenomena taking place in the steam generator (SG) during the experiment. In the current study, the CATHARE code is considered in order to assess a NC characterization test performed in the four loops PKL facility. For this purpose, four different SG nodalizations including, single and multi-U-tubes, 1D and 3D SG inlet/outlet zones are considered. In general, it is shown that the 1D and 3D models exhibit similar prediction results up to a certain point of the rising part of the inverted U-shape of the NC flow curve. After that, the results bifurcate with, on the one hand, a tendency of the 1D models to over-predict the measured NC mass flow rate and on the other hand, a tendency of the 3D models to under-predict the NC flow rate.

• Journal of Environmental Science International
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• v.27 no.3
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• pp.219-225
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• 2018

This study was conducted to investigate the possibility of utilizing various types of nozzles and gas-liquid mixers to increase the dissolution rate of plasma gas containing ozone generated in a dielectric barrier plasma reactor. After selecting the air atomizing nozzle with the highest gas dissolution rate among the 13 types of test equipment, we investigated the influence of the operating factors on the air atomizing nozzle to determine the optimal plasma gas dissolution method. The gas dissolution rate was measured by a simple and indirect method, specifically, the measurement of KLa instead of direct measurement of ozone concentration, which requires a longer analysis time. The results showed that the KLa value of the simple mix of air and water was $0.372min^{-1}$, Which is 1.44 times higher than that ($0.258min^{-1}$) of gas emitted from a normal diffuser. Among the nozzles of the same type, the KLa value was highest for the nozzle having the smallest orifice diameter. Among the 13 types of devices tested, the nozzle with highest KLa value was the M22M nozzle, which is a gas-liquid spray nozzle. The relationship between water circulation flow rate and KLa value in the experimental range was linear. The air supply flow rate and KLa value showed a parabolic-type correlation, while the optimum air supply flow rate for the water circulation flow rate of 1.8 L / min is 1.38 times.

• Journal of the Korean Society for Library and Information Science
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• v.49 no.1
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• pp.201-221
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• 2015

The purpose of this study is to suggest the usability of collection evaluation methods for collection development policy in public libraries. To achieve this purpose, this study applied Bonn's Use Factor, Turnover Rate of Collection, and Trueswell's 80/20 Rule to actual circulation data of the Gwangjin District Public Library in Seoul during last ten years. This study added practical meanings and values in collection evaluation through the analysis of total holdings and subject classes. Main items of analysis are the rate of use to total holdings and to holdings in specific subject classes by year, and the rate of core collection circulation by year. The results show relations between the rate of use and library's performance through the analysis of the rate of use both total holdings and subject classes. The results also figure out user's patterns and library appraisal of community users through the analysis of circulation data. In addition, the analysis of core collection gives a good basis for an effective collection development policy.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.145-158
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• 2015

Disposable marine product packaging materials such as wooden, Styrofoam, and corrugated cardboard boxes have a very low reuse rate, thus causing the logistics costs to rise and making it difficult to establish a unit load system for marine products. Disposable packing containers to be discarded are accompanied by resource and environmental issues home and abroad. Transportation vehicles for marine products have to return empty without loading different kinds of products after delivery due to the smell and properties of marine products, thus posing as an obstacle to logistics rationalization. In an effort to overcome those limitations, this study examined the stages of transportation including "producer-wholesale market in the producing area-commission merchant-wholesale market in the consumption area-commission merchant-quasi-wholesale market-consumer" and also analyzed the utilization and distribution of disposable packaging materials currently used in the circulation of marine products including wooden, Styrofoam, and corrugated cardboard boxes. Based on the analysis results, the investigator developed a logistics rationalization model capable of promoting semi-permanent reuse and lowering empty vehicle rate on return routes as an alternative to address environmental issues caused by disposable packaging materials, which have been an obstacle to the logistics rationalization of marine products, packaging costs in the process of repeating packing and unpacking at each stage of marine products circulation, and empty vehicle rates on return routes after marine products delivery.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.6
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• pp.763-773
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• 2010

The removal efficiencies and a total oxygen transfer coefficient for food waste leachate(FWL) were estimated by using Jet Loop Reactor(JLR). Pure oxygen was used instead of air to improve oxygen concentration in the JLR for high total chemical oxygen demamd(TCOD) in FWL. In JLB, in order to examining the oxygen transfer characteristic, the circulation flowrate and oxygen flowrate were controlled with 7~10 L/min(1.5 L/min interval) and 0.2~0.5 L/min (0.1 L/min interval) and we experimented according to the each condition. As a result, Oxygen uptake rate(OUR) and oxygen transfer rate could be maximized than the oxygen flowrate to increase the circulation flowrate. In addition, it determined that JLR using the pure oxygen which can obtain the greatest oxygen transfer rate as it was the high-concentration organic wastewater like the food waste leachate through the continuous experiment was appropriate.

• Journal of Korean Academy of Nursing
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• v.17 no.2
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• pp.116-121
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• 1987

This study was undertaken to elucidate effects of ingesting small or large amount of tap or iced water on circulation of normal healthy men with the purpose of furnishing basic data for nursing intervention of myocardial infarction patients. The subjects for this study were normal healthy men consisting of 30men and 30women in age from 22 to 30 years. One group consisting of 30men drank 240m1 tap water on day l and 240m1 iced water 24hours later. The other group drank 960m1 tap water on day 1 and 960m1 iced water 24hours later. Blood pressure and heart rate were taken in a sitting position before ingesting water, and immediately after ingesting it and at 2,5,10,15,30 minute intervals thereafter. Changes of heart rate, systolic and diastolic blood pressure after ingesting water were compared with those of preingestive period. The results obtained were as follows : 1. There were no significant changes in blood pressure and heart rater after ingesting small amount of water regardless of its temperature. 2. No significant decrease in blood pressure after ingesting large amount of tap water at all time peroids was noted. 3. A strongly significant interaction effect bet-ween temperature and volume was demonstrated, that is, there was a highly significant decrease in blood pressure and heart rate at all time periods after ingesting large amount of iced water.

• The Journal of Korean Medicine
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• v.23 no.2
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• pp.164-179
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• 2002

Object: Death rate due to hypertension, atherosclerosis, ischemic heart disease and cerebral infarction induced by Westernized diet and increased average life span is on the rise. Decrease in blood circulation, activation of thrombus generation and intravascular lipid accumulation, cited as the principal causes of the above mentioned diseases in recent studies, result in circulatory disturbance and blood vessel obstruction leading to ischemic cell death of heart, brain and peripheral vessels. Method: We investigated the biochemical changes in microvascular permeability, aggregation of platelet and the intravascular lipid accumulation in induced-diabetic rat using Streptozotocin. We also studied the effects of Woohwangcheongsirn-won after oral administration on blood circulation, platelet function and lipid metabolism. The results are as follows: I. Woohwangcheongsim-won increased blood circulation in microvessels. 2. Woohwangcheongsim-won increased the reduced erythrocyte deformability in diabetes. 3. Woohwangcheongsim-won induced the reduction of contents of 2, 3-DPG, but failed to affect the reduced contents of ATP in erythrocyte in diabetes. 4. Woohwangcheongsim-won reduced the activity of Ca/sup 2+/-ATPase in the membrane of erythrocyte. 5. Woohwangcheongsim-won reduced the platelet aggregation evoked by platelet agglutinin factor. 6. Woohwangcheongsim-won reduced the production of platelet-derived granules. 7. Woohwangcheongsim-won reduced the production of metabolites of arachidonic acid in diabetes, and also reduced the production of increased thromboxane B2. 8. Woohwangcheongsim-won reduced the synthesis of oxidized LDL-cholesterol. In conclusion, Woohwangcheongsim-won enhanced blood circulation in microvesseles, erythrocyte deformability and inhibited the increased platelet aggregation and the synthesis of oxidized LDL-cholesterol in diabetes. Therefore Woohwangcheongsim-won is believed to positively affect blood circulation (J Korean Oriental Med 2002;23(2):164-179)

• Journal of Korean Neurosurgical Society
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• v.64 no.1
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• pp.39-50
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• 2021

Objective : The treatment of large aneurysms of the posterior circulation is complicated and remains challenging. We here analyzed our institutional clinical outcomes of large unruptured aneurysms of the posterior circulation. Methods : This study included 56 patients who presented with a large (>10 mm) unruptured aneurysm of the posterior circulation between 2002 and 2018. Results : There were 18 (32.1%) male and 38 (67.9%) female patients, with a mean age of 53.4 years. The most common location was the vertebral artery, followed by the basilar tip and posterior cerebral artery. The median follow-up duration was 29 months. Eighteen patients (32.1%) were treated by transcranial surgery and 38 (67.9%) were treated by endovascular treatment (EVT). Post-treatment complications occurred in 16 patients (28.6%), with there being no significant difference between the transcranial surgery and EVT groups. Complete obliteration was achieved in 30 patients (53.6%), with there being no statistically significant difference between the transcranial surgery and EVT groups. Recurrence occurred in 17 patients (30.4%), and the rate of recurrence was higher in the EVT group than in the transcranial surgery group (39.5% vs. 11.1%, p=0.03). Forty-four (84%) of 56 patients showed a favorable functional outcome. In saccular aneurysm, EVT was negative predictor of worsening of functional status. Conclusion : Treatment of these aneurysms harbors an inherent high risk of morbidity. No superiority was found between transcranial surgery and EVT in terms of complications and complete obliteration, but transcranial surgery showed a higher treatment durability than EVT.

• The Journal of Korean Physical Therapy
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• v.18 no.3
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• pp.71-78
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• 2006

Purpose: The purpose of this study was to investigate how induced microcurrent shoes influenced changes of the blood circulation in patients with Plantar Fasciitis. Methods: Initially, the subjects were comprised of 5 males and 5 females, who agreed with this research and are more than fifty years old, but 4 of those were dropped during the experiment. They all have plantar fasciitis and pain on their feet. Subjects wore the induced microcurrent shoes for more than 4 hours everyday during 4 weeks. When they wore those shoes, they also wore the specially produced shocks made of silver-mixed thread and they were asked to avoid intense exercise. Assessments were carried out before and after walking on a treadmill and we measured changes between the test before and after 4 weeks. In the examination of the before test, general shoes were used, and in the examination of the after test, induced microcurrent shoes were used. Temperature difference was measured by thermograpy DOREX spectrum 9000MB(USA). Subjects walked total 20 minutes and during gait, the walking rate on a treadmill was increased from 2Km/h to 3Km/h after 10 minutes. We measured plantar temperature by thermograpy especially both heel, 1st, and 5th metatarsal areas. Results: Firstly, in comparison of the blood circulation on the left and right foot at 0 week and 4 weeks, it tended toward increasing blood circulation but there was. no statistically significant difference (p>0.05). Secondly, in comparison of the blood circulation before and after treadmill with the induced microcurrent shoes, the blood circulation of the heel and the 5th area on the right foot was increased to all subjects(p<0.05). Conclusion: The results of this study revealed that subjects showed tendency to increase blood circulation in both right and left feet after wearing microcurrent shoes and specially after walking treadmill at 4 weeks. Therefore induced microcurrent shoes are useful to improve blood circulation for patients with plantar fasciitis.