• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.2
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• pp.228-233
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• 2022

Arteriovenous malformations (AVMs) are rare congenital anomalies characterized by direct communication between arteries and veins that bypass the capillary bed. AVMs may not manifest clinically until late infancy or childhood. In particular, facial AVMs can cause urgent life-threatening dental events. A 5-year-old girl without a medical history visited the hospital because of spontaneous gingival bleeding around the posterior gingival area of the lower left 2nd primary molar. Angiography through the femoral approach under general anesthesia was performed for differential diagnosis and therapeutic option. The blood flow was effectively reduced after arterial embolization alone, and there was no evidence of recurrence at the 5-month follow-up. The present study reports that embolization of the affected vessels can be a more effective and safe method than surgical resection for the treatment of AVM during the growth period.

• Journal of Chest Surgery
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• v.31 no.6
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• pp.553-559
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• 1998

Introduction: The most dramatic application of hypothermia in cardiac surgery is in deep hypothermic circulatory arrest(DHCA). Because man in natural circumstances is never exposed to this extreme hypothermic condition, one of the controversial aspects of clinical hypothermia is appropriate acid-base management($\alpha$-stat versus pH-stat). This study aims to compare $\alpha$-stat with pH-stat for: (1) brain cooling and re-warming speed during hypothermia induction and re-warming by cardiopulmonary bypass (CPB); (2) cerebral perfusion, metabolism, and their coupling; and (3) the extent of development of cerebral edema after circulatory arrest, in young pigs. Materials & Methods: Fourteen young pigs were assigned to one of two strategies of gas manipulation. Cerebral blood flow was measured with a cerebral venous outflow technique. After a median sternotomy, CPB was established. Core cooling was initiated and continued until nasopHaryngeal temperature fell below $20^{\circ}C$. The flow rate was set at 2,500 ml/min. Once their temperatures were below $20^{\circ}C$, the animals were subjected to DHCA for 40 mins. During cooling, acid-base balance was maintained according to either $\alpha$-STAT or pH-STAT strategies. After DHCA, the body was re-warmed to normal body temperature. The animals were then sacrificed, and their brains measured for edema. Cerebral perfusion and metabolism were measured before the onset of CPB, before cooling, before DHCA, 15 mins after re-warming, and upon completion of re-warming. Results & Conclusion: Cooling time was significantly shorter with $\alpha$-stat than with pH-stat strategy, while there were no significant differences in rewarming time between the two groups. Nosignificant differences were found in cerebral blood flow, metabolic rate, or flow/ metabolic rate ratio between two groups. Temperature-related differences were significant in cerebral blood flow, metabolic rate, and flow/metabolic rate ratio within each group. Brain water content showed no significant differences between two groups.

• Clinical and Experimental Pediatrics
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• v.48 no.3
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• pp.321-326
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• 2005

Kawasaki disease is an acute systemic vasculitis of unknown origin. Giant coronary aneurysm is one of the most serious complications, although peripheral artery vasculitis can produce life-threatening events. Myocardial ischemia and infarction can be caused by coronary artery stenosis, aneurysm, and stagnation of blood flow in coronary arteries which triggers thromboembolism. Atypical presentation in young infants often interferes with prompt diagnosis and timely treatment, resulting in poor outcomes. We describe a 3-month-old infant with multiple giant coronary aneurysms with flow stagnation, stenosis and large mural thrombus due to Kawasaki disease. He presented with a prolonged course of severe coronary involvement in spite of all measures to reduce coronary complications. Finally, surgical intervention was tried because of the worsening coronary artery abnormalities. The patient died of acute cardiorespiratory failure shortly after weaning from cardiopulmonary bypass.

• Journal of Chest Surgery
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• v.8 no.2
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• pp.135-142
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• 1975

Total body perfusion using Sarns Heart-Lung-Machine, five head pump motor system with Travenol disposable bubble oxygenator was attempted in the dogs by the hemodilution method with total prime of buffered Hartman`s solution under moderate hypothermia. The first of all, the functions of Sarns Heart-Lung-Machine and effects of the hemodilution perfusion by buffered Hartman`s solution was studied. At the same time the changes of pressure of artery and vein, gas contents of the blood, and influence on the blood pictures were observed before, during, and after perfusion in 1-2 days. Hemodilution rates were the ranges of 85.0ml/kg to 97.3ml/kg and perfusion flow rates were maintained with the average 80. 5ml/kg/min [the ranges of 73.3ml/kg/min to 92.8ml/kg/min]. Hypothermia was employed between $35^{\circ}C$ and $31^{\circ} of the esophageal temperature. The total body perfusion was continued for 50-60 minutes. In the total cardiopulmonary bypass, atriotomy, ventriculotomy, and atrioventriculotomy were performed respectively. Arterial pressure was ranged approximately between 50 mmHg and 140 mmHg, but generally, it was maintained over 75 mmHg. Venous pressure was measured between 3.8 cm$H_2O$ and 16.0 cm$H_2O$. Optimum oxygenation could be achieved when oxygen flow into the oxygenator was maintained approximately at 5. 5L/min. In this way, the $pO_2$, $pCO_2$, and oxygen saturation were measured before, during, and afterperfusion in 1-2 days. The $pCO_2$ ranged approximately between 26.0 mmHg and 38.5 mmHg, but generally, it was maintained in the average 30.9-32.5mmHg. The $pO_2$ was ranged between 73.0mmHg and 332.2 mmHg, but it was maintained in the average 103.0-219.0 mmHg. Oxygen saturation was measured over 95. 0% during and after extracorporeal circulation respectively. Erythrocyte count, hemoglobin, hematocrit, and leucocyte count were decreased to 49.2%, 49.0%, 49.4%, and 21. 1% of the preoperative value during extracorporeal circulation respectively and these reductions were not recovered until 1-2 days after perfusion. These. resulted from relatively high degree of hemodilution rate and operative bleeding during these experimental studies. The platelets count was also decreased about to 71% during perfusion, on the contrary, it was increased progressively after perfusion and in 1-21 days after perfusion, the value was returned to preoperative contro1 level. Three dogs were all recovered after extracorporeal circulation.

• Journal of Animal Science and Technology
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• v.45 no.4
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• pp.617-626
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• 2003

This experiment employed a rumen simulated continuous culture system to examine the possibility of improving the rumen bypass of polyunsaturated fatty acids (PUFA) by using a high proportion of concentrate in the feed, and compared soya and linseed in terms of conjugated linoleic acid (CLA) production. No effect of type of fat source was observed on ruminal fermentation. A high proportion of concentrate (80%) in the feed decreased (P<0.001) vessel pH but increased (P<0.01) ammonia nitrogen, total VFA, acetate, butyrate and valerate concentrations compared with a low proportion (40%). Fat sources (soya vs. linseed) and concentrate ratio in the feed did not affect digestibilities of organic matter (OM), total nitrogen, neutral detergent fiber (NDF) and acid detergent fiber (ADF). Soya increased the flows of trans C18:1, C18:2 n-6 and C18:3 n-3 compared with linseed. The difference in fat source alone did not affect the flow of CLA but this was increased when high levels of soya and linseed were associated with a high proportion of concentrate in the feed. There was no effect of fat source on biohydrogenation of C18:1 n-9 and C18:2 n-6, but biohydrogenation of C18:3 n-3 and total C18 PUFA was higher with the linseed than with the soya treatment. A high proportion of concentrate decreased biohydrogenation of C18:2 n-6, C18:3 n-3 and total C18 PUFA compared with a low proportion.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.1-14
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• 2015

In case of a gas turbine engine for supersonic operation, the engine have a wide range of operating inlet mass flow rate and required high performance such as thrust and fuel consumption. Therefore, variable system and its optimal control logic are essentially needed. In this work, a method for performance prediction of a gas turbine engine with variable system compressor and its control scheme were developed. Conceptual design of compact acuation system for the operation of the variable system was also conducted. The performance of a low-bypass ratio mixed flow turbofan engine was analyzed, and it was observed that the surge margin of the engine is improved at off-design condition by applying the control scheme.

• Journal of the Korean Institute of Intelligent Systems
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• v.3 no.2
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• pp.18-35
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• 1993

The water level control system of the steam generator in a pressurized water reactor and its control problems are analysed. In this work the stable control strategy during the low power operation and transient states is studied. To solve the problem, a fuzzy logic control method is applied as a basic algorithm of the controller. The control algorithm is based on the operator's knowledges and the experiences of manual operation for water level control at the compact nuclear simulator set up in Korea Atomic Energy Research Institute. From a viewpoint of the system realization, the control variables and rules are established considering simpler tuning and the input-output relation. The control strategy includes the dynamic tuning method and employs a substitutional information using the bypass valve opening instead of incorrectly measured signal at the low flow rate as the fuzzy variable of the flow rate during the pressure control mode of the steam generator. It also involves the switching algorithm between the control valves to suppress the perturbation of water level. The simulation results show that both of the fine control action at the small level error and the quick response at the large level error can be obtained and that the performance of the controller is improved.

• Fire Science and Engineering
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• v.27 no.3
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• pp.30-37
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• 2013

The ultimate purpose of the present study is to secure a effective method for foam liquid discharge when the mixing ratio deviates from the permissible range due to a decrease in the bypass flow rate resulting from a decrease in the cross sectional area of the foam liquid piping ranging from the branching header of one foam proportioner to the branching headers of multiple branching foam fire-extinguishing systems in the region for fire extinguishing and then to the standpipe at the lower part of the storage tank when a fire occurred in a combustible tank. To this end, the cause of mixing ratio variations following changes in the flow rates of existing foam fire extinguishing systems was analyzed, methods for compensation for constant mixing ratios were investigated, and it was proved that metering orifice replacements that could expand the cross sectional area of the stock solution inhaling piping was the most effective way for the improvement of form fire extinguishing systems' mixing ratios through foam proportioner venturi, foam chamber orifice, and metering orifice replacement experiments.

• Journal of Chest Surgery
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• v.3 no.2
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• pp.73-90
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• 1970

Clinical perfusion data on 16 cases of cardiopulmonary bypass using Sigmamotor pump and RyggKyvsgaard Oxygenator which performed at Seoul National University Hospital during the period of Aug. 1968 to Aug. 1970 was analized. AIl cases were hemodiluted and the perfusion was carried out under the normothermic condition. The age of the patients ranged between 6 and 43 years. The b:dy weight varied between 18.3 and 54.0 kg and the body surface area between 0.78 and 1. 59$M^2$. The priming solution was consiste:I with fresh ACD blood. Hartmann solution and Mannitol. The average amount of priming was approximately 2242 ml. The average hemodilution rate was 17%. The flow rate ranged from 1.7L to 3.5L/Min/$M^2$ and averaged 2.4L/Min/$M^2$ or 78mI/Min/kg. The duration of perfusion varied from 22 to 110 min with average of 56.9 minutes. Some hemodynamic responses were observed. The arterial pressure dropped immediately after the initiation of partial perfusion and was more marked after the total perfusion foIlowed by gradual increase to the safety level. The central venous pressure reflected the reduced blood volume especially in the cases of prolonged perfusion which lasted over 60 min. In most of the cases, red blood cell count decreased and white blood ceIl count increased after the perfusion. Hemoglobin level was decreased, averaging of 12.5mg%, Hct 3.3% and platelets count of 18% postoperatively. Plasma hemoglobin increased mildly, from pre-perfusion average value of 4. 06mg% to postperfusion value of 22.5mg%. Serum potassium was 4.4mEq/L pre-operatively and was decreased to 3.7mEq/L postoperatively. Five cases showed definite hypopotassemia immediately after the operation. Sodium and chloride decreased mildly. These electrolyte changes are thought to be related with hemodilution. diuretics and reduced blood volume during and after the perfusion. Arterial blood pH value revealed minimal to moderate elevation from preperfusion average value of 7.376 to 7.461 during perfusion and then 7.365 after perfusion. The pC02 and hicarbonate showed minimal to moderately lowered values. The total CO2 was decreased. Buffer base decreased during perfusion (Av. 42.6mEq/L) and further decreased after the perfusion (Av. 40.8mEq/L). These arterial blood acid base changes suggested that the metabolic acidosis was accompanied by respiratory alkalosis during and immediately after the perfusion. Authors belived that the acidosis could more effectively be corrected with the more additional dose of bicarbonate than we used by this study. The chest tune drainage during the first 24 hours following operation was 1158 ml in average. One case (Case No. 15) showd definite bleeding tendency and it was believed that the cause might be due to the defect of heparin and protamine titration. The average urinary out put during 24 hours post-perfusion was 1291ml. One case (Case No. ]) showed definite post perfusion oliguria. As conclusion hemodilution using fresh ACD blood. Hartmann and Mannitol solution added with Bivon and high flow rate unler normothermia. was thought to amelioratc the severity of mctabolic acidosis during and after perfusion with relatively satisfactory effect on the diuresis and bleeding tendency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.34-44
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• 2016

This study is an experimental study about a facility for preventing the accumulation of floating debris at a bridge by flooding at a small river. Generally, structures installed at a small river are damaged frequently by floating debris during typhoons or localized rainfall events. On the other hand, there is no method available for preventing such damage. The facilities used in other countries to prevent such damage by the accumulation of floating debris include debris fins, deflectors, and sweeper. Among these facilities, the present study was conducted with a sweeper to investigate the damage-reducing capability through a real-scale accumulation experiment. A sweeper was installed in front of a bridge to bypass floating debris by self-rotation so that the floating debris may not be accumulate at the bridge. A small bridge model was prepared in a real-scale for the real-scale experiment. The accumulation reducing capability was compared through an accumulation experiment before and after the sweeper installation depending on the length of the debris and flow conditions. The result showed that the accumulation rate increased with increasing length of the debris or decreasing flow rate. The installation of a sweeper decreased the debris accumulation rate by a minimum of 55% to a maximum of 88% compared to the case without an installed sweeper. The result of the present study showed that the installation of a sweeper at a small river having a high potential of generating floating debris may help secure the stability of a bridge in the case of floating debris accumulation.