• Journal of the Korean GEO-environmental Society
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• v.16 no.1
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• pp.29-36
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• 2015

Current domestic research is to demonstrate the effectiveness and efficiencies of flood prevention measures through one-dimensional numerical analysis and this study's object is to help water managers to make the efficient decisions by applying the two-dimensional urban run off model XP-SWMM model in the flooded area and comparing with the flood prevention measures. Statistics were analyzed, based on the data collected from Cheongju Weather Service from 1967 to 2011 for 45 years. 50 years Flood frequency simulations of water flow capacity analysis of the target area for flooded areas $539,548m^2$, inundation depth 1.0 m, was analyzed by inundation time of 48 minutes. When comparing with the constructions of bypass road and underground storage facilities to increase the water flow capacity of A1 small drainage areas as flood protection, if you install a batching target underground detention basin with a capacity of $13,500m^3$, it is expected that the flood by rainfall with frequency of 50 years will be resolved completely. In preparation for extreme weather in the future flood mitigation measures, underground storage tank installation is considered a better efficient way.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.2
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• pp.219-233
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• 2010

Understanding the Nano size particles is of great interest due to their chemical and physical behaviors such as compositions, size distributions, and number concentrations. Therefore, accurate measurements of size distributions and number concentrations in ultrafine particles are getting required because expected losses such as diffusion for the instrument system from ambient inlet to detector are a significant challenge. In this study, the data using the computed settling losses, impaction losses, diffusion losses for the sampling lines (explored different sampling line diameters, horizontal length, number of bending, line angles, flow rates with and without a bypass), and diffusion losses for the Scanning Mobility Particle Sizers are examined. As expected, the settling losses and impaction losses are very minor under 100 nm, however, diffusion loss corrections for the sampling lines and the size instrument make a large difference for any measurement conditions with high numbers of particles smaller mobility size. Both with and without the loss corrections, which can affect to size distributions and number concentrations are described. First, 80% or more of the smallest particles (less than 10 nm) can be lost in the condition of a flow rate of 0.3 liter per minute and the length of sampling line of 1.0 m, second, total number concentrations of measurements are quite significantly affected, and the mode structure of the size distribution changes dramatically after the loss corrections applied. With compared to the different measurements, statistically diffusion loss corrections yield a required process of the ambient particle concentrations. Based on the current study, as an implication, a possibility of establishing direct revelation mechanisms is suggested.

• Journal of Yeungnam Medical Science
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• v.11 no.1
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• pp.49-54
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• 1994

Postoperative brain damage is one of most serious complications of cardiopulmonary bypass (CPB). To prevent brain damage during CPB, adequate cerebral perfusion for cerebral oxygen demand should be maintained. This study monitored jugular venous oxyhemoglobin saturation ($SjO_2$), which reflects the overall balance of cerebral oxygen supply and demand, intermittently in 10 patients undergoing cardiac surgery. At the initiation of CPB, in spite of a significant decrease in mean arterial pressure, $SjO_2$ did not change, and it was stable during the hypothermic period of CPB. But a significan reduction in $SjO_2$ was observed during the rewarming period, and $SjO_2$ had an inverse linear correlation with esophageal temperature. Furthermore, the percent decrease of $SjO_2$ was related to rewarming speed. Therefore, therapeutic approaches for $SjO_2$ desaturation include slower rewarming, increasing cerebral blood flow, decreasing the cerebral metabolic rate for oxygen, increasing oxygen content, and increasing perfusion flow rate.

• Journal of Preventive Medicine and Public Health
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• v.50 no.1
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• pp.29-37
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• 2017

Objectives: The accurate measurement of geographic patterns of health care utilization is a prerequisite for the study of geographic variations in health care utilization. While several measures have been developed to measure how accurately geographic units reflect the health care utilization patterns of residents, they have been only applied to hospitalization and need further evaluation. This study aimed to evaluate geographic indices describing health care utilization. Methods: We measured the utilization rate and four health care utilization indices (localization index, outflow index, inflow index, and net patient flow) for eight major procedures (coronary artery bypass graft surgery, percutaneous transluminal coronary angioplasty, surgery after hip fracture, knee replacement surgery, caesarean sections, hysterectomy, computed tomography scans, and magnetic resonance imaging scans) according to three levels of geographic units in Korea. Data were obtained from the National Health Insurance database in Korea. We evaluated the associations among the health care utilization indices and the utilization rates. Results: In higher-level geographic units, the localization index tended to be high, while the inflow index and outflow index were lower. The indices showed different patterns depending on the procedure. A strong negative correlation between the localization index and the outflow index was observed for all procedures. Net patient flow showed a moderate positive correlation with the localization index and the inflow index. Conclusions: Health care utilization indices can be used as a proxy to describe the utilization pattern of a procedure in a geographic unit.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.513-520
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• 2004

A steady-state/transient performance simulation model was newly developed for the propulsion system of the CRW (Canard Rotor Wing) type UAV (Unmanned Aerial Vehicle) during flight mode transition. The CRW type UAV has a new concept RPV (Remotely Piloted Vehicle) which can fly at two flight modes such as the take-off/landing and low speed forward flight mode using the rotary wing driven by engine bypass exhaust gas and the high speed forward flight mode using the stopped wing and main engine thrust. The propulsion system of the CRW type UAV consists of the main engine system and the duct system. The flight vehicle may generally select a proper type and specific engine with acceptable thrust level to meet the flight mission in the propulsion system design phase. In this study, a turbojet engine with one spool was selected by decision of the vehicle system designer, and the duct system is composed of main duct, rotor duct, master valve, rotor tip-jet nozzles, and variable area main nozzle. In order to establish the safe flight mode transition region of the propulsion system, steady-state and transient performance simulation should be needed. Using this simulation model, the optimal fuel flow schedules were obtained to keep the proper surge margin and the turbine inlet temperature limitation through steady-state and transient performance estimation. Furthermore, these analysis results will be used to the control optimization of the propulsion system, later. In the transient performance model, ICV (Inter-Component Volume) model was used. The performance analysis using the developed models was performed at various flight conditions and fuel flow schedules, and these results could set the safe flight mode transition region to satisfy the turbine inlet temperature overshoot limitation as well as the compressor surge margin. Because the engine performance simulation results without the duct system were well agreed with the engine manufacturer's data and the analysis results using a commercial program, it was confirmed that the validity of the proposed performance model was verified. However, the propulsion system performance model including the duct system will be compared with experimental measuring data, later.

• Nuclear Engineering and Technology
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• v.22 no.1
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• pp.12-19
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• 1990

The Loss of Offsite Power Transient at 77.5% power which occurred on June 9, 1981 at the Kori Unit 1 PWR (Pressurized Water Reactor) is simulated using the RELAP5/MOD2 system thermal-hydraulics computer code. Major thermal-hydraulic parameters are compared with the available plant data. The comparison of the analysis results with the plant data demonstrates that the RELAP5/MOD2 code has the capability to simulate the thermal-hydraulic behaviour of PWRs under accident conditions of this type with accuracy, except the pressurizer pressure and level. The pressurizer pressure increase is sensitive to the in surge now it is believed that the interracial heat transfer in a horizontal stratified flow regime may be estimated low and the compression effect due to insurge flow may be high. In the nodalization sensitivity study it is found that S/G noding with junctions between bypass plenum and steam dome is preferred to simulate the S/G water level decreasing and avoid the spurious level peak at trubine trip.

• Journal of Chest Surgery
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• v.36 no.7
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• pp.472-482
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• 2003

Recent studies have demonstrated that cerebral desaturation during rewarming period of CPB was associated with postoperative neurologic dysfunction. The prevention of cerebral desaturation during CPB may reduce the incidences of neurologic and neuropsychological complications. The present study was prospectively undertaken to compare the clinical effects between two strategies (hypercapnic CPB and high flow CPB) to prevent cerebral desaturation for establishing a proper CPB technique. Material and Method: Thirty-six adult patients scheduled for elective cardiac surgery were randomized into either hypercapnic (Pa$CO_2$ 45~50mmHg, n＝18) or high flow group (flow rate 2.75 L/ $m^2$/min and Pa$CO_2$ 35~40mmHg, n＝18) during rewarming period of CPB. In each patient, middle cerebral artery blood flow velocity ( $V_{MCA}$), cerebral arteriovenous oxygen content difference (C(a-v) $O_2$), modified cerebral metabolic rate for oxygen (MCMR $O_2$), cerebral oxygen transport rate ( $T_{E}$ $O_2$), incidence of cerebral desaturation (internal jugular bulb blood oxygen saturation $\leq$ 50%), increased rate of S-100 $\beta$ concentration, and arterial and internal jugular bulb blood gas were measured during the five phases of the operation; Pre-CPB, CPB-10 min (steady-state CPB, nasopharyngeal temperature 29~3$0^{\circ}C$), Rewarm-1 (rewarming phase, nasopharyngeal temperature 33$^{\circ}C$), Rewarm-2 (nasopharyngeal temperature 37$^{\circ}C$), and CPB-off. Incidence of postoperative delirium and duration were assessed in all patients. All variables were compared between the two groups. Result: $V_{MCA}$ (157.88$\pm$10.87 vs 120.00$\pm$6.18%, p＝0.006), internal jugular bulb $O_2$ saturation (68.01$\pm$2.75 vs 61.28$\pm$2.87%, p＝0.03) and $O_2$ tension (41.01$\pm$2.25 vs 32.02$\pm$ 1,67 mmHg, p＝0.03), and $T_{E}$ $O_2$(110.84$\pm$7.41 vs 81.15$\pm$8.11%, p＝0.003) at rewarming periods were higher in the hypercapnic group than in the high flow group. C(a-v) $O_2$ (4.0$\pm$0.30 vs 4.84$\pm$0.38 mg/dL, p＝0.04), COE (0.36$\pm$0.03 vs 0.42$\pm$0.03, p＝0.04), increased rate of S- 100$\beta$ (391.67$\pm$23.40 vs 940.0$\pm$17.02%, p＝0.003), and incidence of cerebral desaturation (2 vs 4 patients, p＝0.04) at rewarming periods, and duration of postoperative delirium (18 vs 34 hr, p＝0.02) were low in the hypercapnic group compared to the high flow group. Conclusion: These results indicate that hypercapnic CPB may provide relatively diminished cerebral injury and beneficial effects for cerebral metabolism relatively compared to high flow CPB.low CPB.

• Journal of Chest Surgery
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• v.35 no.1
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• pp.20-26
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• 2002

Background: Due to the concern of flow competition or retrograde steal, it has been generally suggested that the right gastroepiploic artery(RGEA) pedicled graft should be used in critical coronary stenosis lesion. The study was designed to evaluate the potential of retrograde flow competition in the RGEA pedicled graft by measuring the native pressure differences(PD) between the normal coronary artery and celiac arterial pressure, which would be compared with trans-stenosis pressure gradients(TSPG) in coronary artery occlusive disease. Material and Method: Between July, 1998 and February, 1999, pressures of the right coronary artery and the right gastroepiploic artery(or the celiac artery) were measured in patients with the patent right coronary artery(n=12). The PD between the arteries was compared with the TSPG in the occlusive coronary arteries(n=32). Result: The pressures of the normal right coronary artery and celiac artery were 143$\pm$23 vs. 134$\pm$17mmHg in systole(p<0.005), 74$\pm$13 vs. 73$\pm$14mmHg in diastole(p=NS), and 100$\pm$16 vs. 97$\pm$15mmHg in mean (p<0.05). The PD between the arteries were -8~25mmHg in systole, -4~7mmHg in diastole, and -1~10mmHg in mean. The TSPG measured in the occlusive coronary arteries were -4~19(7$\pm$5.8)mmHg in the lesion less than 75% stenosis vs. 7~74(27$\pm$18.3)mmHg in the 75% or over stenosis lesion(p<0.005). The normally existing pressure difference between the coronary arteries and RGEA(15~20mmHg) was significantlyless than the TSPG in .the occlusive coronary artery with 75% or over stenosis(p<0.001). Conclusion: If the pressure gradient between the RGEA and the coronary artery distal to the stenosis is the main determinant of development of retrograde flow competiton in the RGEA pedicled graft, the above data suggests that there will be little chance of competition when It is used in the coronary lesion with 75% or over stenosis.

• Journal of Chest Surgery
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• v.21 no.2
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• pp.211-222
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• 1988

Tetralogy of Fallot is a cyanotic congenital heart disease characterized by large ventricular septal defect[VSD] and stenosis of right ventricular outflow tract[RVOT] and the degree of RVOT stenosis and the state of pulmonary arteries are the major determinant of prognosis of this anomaly after operation. The sum of blood flow through RVOT and collateral flow from systemic arteries determine the total pulmonary blood flow and it is drained to left atrium and left ventricle. Therefore the degree of development of left ventricle not only reflects pulmonary blood flow and the status of peripheral pulmonary arteries but also affects postoperative prognosis as a systemic ventricle. In this article, left ventricular volume and its influence on postoperative cardiac function in tetralogy of Fallot were studied in 34 patients operated on at Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital in 1985. Mean age of the patients was 5 1/12*3 9/12 years[range 9/12 - 14 8/12 years], mean body surface area[BSA] 0.65*0.20m2[range 0.38 - 1.22m2], mean body weight 15.6k6.48kg[range 7.0 - 36kg]and mean hematocrit 50.6*9.77%[range 32.0 - 73.5%]. Left ventricular end-diastolic volume[LVEDV] of them were from 11.2 to 113cc and there was a good linear correlation between BSA[m2, X]and LVEDV[cc, Y][Y= - 20.0+923x, r= 0.84, p < 0.005]. Mean LVEDV/m2 was [57.6 * 18.3 cc / m2[range 28.7 - 95.8 cc / m2] and there was a significant reduction of volume compared with normal value. As body surface increases, there was a increasing tendency in LVEDV/m2 but there was no statistical significance. Mean total amount of postoperatively infused dopamine in these 33 patients[except one who expired postoperatively] was 65.6*74.5mg / kg and it was 40.6*44.0mg / kg in routine RVOT widening group [Group I] and 205*49.3mg / kg in transannular RVOT widening group[Group II]. There was a statistically significant difference between two groups. In group I patients there was a good linear inverse correlation between dopamine total amount[mg / kg, Y] and LV volume[cc / m2, X] [Y = 150 - 1.89 X, r = - 0. 77, p < 0.005]. But there were no correlations between dopamine total amount and Hct, cardiopulmonary bypass time and aorta cross clamp time. In conclusion, the patient with small preoperative left ventricular volume required more amount of dopamine as an inotropic agent for the maintenance of a cardiac function in postoperative period. But this is a result of immediate postoperative period and does not reflect the long term effect of left ventricular volume in tetralogy of Fallot. There must be more study for the evaluation of its long term effect.

• Journal of Chest Surgery
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• v.41 no.3
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• pp.329-334
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• 2008

Background: Percutaneous cardiopulmonary support. (PCPS) has the potential to rescue patients in cardiogenic shock who might otherwise die. PCPS has been a therapeutic option in a variety of the clinical settings such as for patients with myocardial Infarction, high-risk coronary intervention and postcardiotomy cardiogenic shock, and the PCPS device is easy to install. We report our early experience with PCPS as a life saving procedure in cardiogenic shock patients due to acute myocardial infarction. Material and Method: From January 2005 to December 2006, eight patients in cardiogenic shock with acute myocardial infarction underwent PCPS using the CAPIOX emergency bypass system($EBS^{(R)}$, Terumo, Tokyo, Japan). Uptake cannulae were inserted deep into the femoral vein up to the right atrium and return cannulae were inserted into the femoral artery with Seldinger techniques using 20 and 16-French cannulae, respectively. Simultaneously, autopriming was performed at the $EBS^{(R)}$ circuit. The $EBS^{(R)}$ flow rate was maintained between $2.5{\sim}3.0L/min/m^2$ and anticoagulation was performed using intravenous heparin with an ACT level above 200 seconds. Result: The mean age of patients was $61.1{\pm}14.2$ years (range, 39 to 77 years). Three patients were under control of the $EBS^{(R)}$ before percutaneous coronary intervention (PCI), three patients were under control of the $EBS^{(R)}$ during PCI, one patient was under control of the $EBS^{(R)}$ after PCI, and one patient was under control of the $EBS^{(R)}$ after coronary bypass surgery. The mean support time was $47.5{\pm}27.9$ hours (range, 8 to 76 hours). Five patients (62.5%) could be weaned from the $EBS^{(R)}$ after $53.6{\pm}27.2$ hours. (range, 12 to 68 hours) of support. All of the patients who could successfully be weaned from support were discharged from the hospital. There were three complications: one case of gastrointestinal bleeding and two cases of acute renal failure. Two of the three mortality cases were under cardiac arrest before $EBS^{(R)}$ support, and one patient had an intractable ventricular arrhythmia during the support. All of the discharged patients are still surviving at $16.8{\pm}3.1$ months (range, 12 to 20 months) of follow-up. Conclusion: The use of $EBS^{(R)}$ for cardiogenic shock caused by an acute myocardial infarction could rescue patients who might otherwise have died. Successfully recovered patients after $EBS^{(R)}$ treatment have survived without severe complications. More experience and additional clinical investigations are necessary to elucidate the proper installation timing and management protocol of the $EBS^{(R)}$ in the future.