• Nuclear Engineering and Technology
• /
• v.25 no.1
• /
• pp.91-101
• /
• 1993

To predict accurately the thermal hydraulic behavior of light water reactors during normal or abnormal operation, the accurate estimation of the void distribution is required. Up to date, many techniques for predicting void fraction of two-phase flow systems have been suggested. Among these techniques, the drift-flux model is widely used because of its exact calculation ability and simplicity. However, to get more accurate prediction of void fraction using drift-flux model, slip and flow regime effects must be considered more properly In the drift-flux method, these two effects are accounted for by two drift-flux parameters ; $C_{o}$ and (equation omitted). At earlier stage, $C_{o}$ is measured in a circular tube. In this study, $C_{o}$ is experimentally determined by measuring local void fraction and vapor velocity distribution in a rectangular subchannel having 4 heating rods which simulates nuclear subchannels. The measurements are peformed with two-electrical conductivity probes which are known to be adequate for measuring local parameters. The experiments are performed at low flow rate and the system pressure less than 3 atmo spheric pressure. In this experiment, (equation omitted), is not measured, but quoted from well-known empirical correlation to formulate $C_{o}$. Finally, $C_{o}$ is expressed as a function of channel averaged void fraction. fraction.

• Journal of the Korean Institute of Gas
• /
• v.27 no.3
• /
• pp.41-51
• /
• 2023

As abnormal climatic event occur frequently due to global warming, many nations have proclaimed their commitment to achieving carbon neutrality and are actively pursuing a transition toward a hydrogen economy. At this time, ammonia has garnered significant attention not only as a high-capacity hydrogen carrier but also as a promising candidate as a carbon-free fuel. In particular, anion exchange membrane fuel cells offer the advantage of directly supplying ammonia to the fuel cell, eliminating the necessity for separate ammonia decomposition or hydrogen purification. Therefore, in this study, the operation principle and research trend of the anion exchange membrane fuel cell are reviewed, and several research using ammonia as a fuel in anion exchange membrane fuel cell are also investigated.

• Korean Journal of Remote Sensing
• /
• v.39 no.5_2
• /
• pp.755-770
• /
• 2023

Due to recent severe climate change, abnormal weather phenomena, and other factors, the frequency and magnitude of natural disasters are increasing. The need for disaster management using artificial satellites is growing, especially during large-scale disasters due to time and economic constraints. In this study, we have summarized the current status of next-generation medium-sized satellites and microsatellites in operation and under development, as well as trends in satellite imagery analysis techniques using a large volume of satellite imagery driven by the advancement of the space industry. Furthermore, by utilizing satellite imagery, particularly focusing on recent major disasters such as floods, landslides, droughts, and wildfires, we have confirmed how satellite imagery can be employed for damage analysis, thereby establishing its potential for disaster management. Through this study, we have presented satellite development and operational statuses, recent trends in satellite imagery analysis technology, and proposed disaster response strategies that utilize various types of satellite imagery. It was observed that during the stages of disaster progression, the utilization of satellite imagery is more prominent in the response and recovery stages than in the prevention and preparedness stages. In the future, with the availability of diverse imagery, we plan to research the fusion of cutting-edge technologies like artificial intelligence and deep learning, and their applicability for effective disaster management.

• Tuberculosis and Respiratory Diseases
• /
• v.51 no.2
• /
• pp.147-154
• /
• 2001

Background : Bronchoscopy has been widely used for a histologic diagnosis through a transbronchial lung biopsy or for staging of patients with peripheral lung cancer. However a transthoracic needle aspiration (TTNA) has been used more widely for a histologic diagnosis in patient with a small size nodule or a nodule located in the outer portion of the lung because of the low diagnostic yield of bronchoscopy in these cases. The role of bronchoscopy for staging is not well established in patients with peripheral lung cancer diagnosed by a TTNA or patients who are undergoing surgery without a histologic diagnosis. Method: To evaluate the role of bronchoscopy for the staging in patients with peripheral lung cancer, who were diagnosed by TTNA, the medical records of 86 patients with peripheral lung cancer who underwent bronchoscopyat Kyungpook National University Hospital between January 1995 and May 1997 were reviewed. Results : While 53 cases had normal bronchoscopic findings, 33 cases had abnormal bronchoscopic findings comprising 9 cases of tumor, 10 cases of infiltration and 14 cases of compression of which there were 25 cases of T1 and 8 T2 endoscopically. The bronchoscopic staging did not influence the changes of the clinical stage of lung cancer. The frequencies of bronchial involvement tended to increase as the sizes of the nodule increased. Among the 42 patients who underwent surgery, 9 patients staged higher after operation because of lymph node involvement in 8 patients and the involvement of the pulmonary artery in 1 patient. No case staged above after operation due to a bronchial invasion. Conclusion : These findings suggests that bronchoscopy is not useful for staging in patients with peripheral lung cancer diagnosed by a TTNA.

• Journal of the Korean Arthroscopy Society
• /
• v.13 no.1
• /
• pp.8-13
• /
• 2009

Purpose: We used tibialis allograft for the reconstruction of ACL and used Hybrid femoral fixation utilizing $Endobutton^{(R)}$ and $Rigidfix^{(R)}$ for femoral fixation, and used $Retroscrew^{(R)}$ and additional fixation for tibial fixation to evaluate the clinical results. Materials and Methods: The ACL reconstruction were performed from February 2004 to February 2007 utilizing Hybrid femoral fixation and $Retroscrew^{(R)}$ and 32 patients, 32 cases which were available for year-long observation (12 to 25 months). The clinical results (Lysholm knee score, IKDC grade) and the radiologic results(bone tunnel expansion, Telos anterior displacement test) were evaluated. Results: The Lysholm knee score was improved from the average of $67.9{\pm}5.4$ points (range: 51~77) before operation and to $94.1{\pm}6.8$ points (range: 68~98) at the last follow up (p<0.05). 22 cases (69%) were evaluated normal (A), 9 cases (28%) were evaluated nearly normal (B) and only 1 case (3%) was evaluated not normal (C) at IKDC final evaluation and no case was evaluated abnormal. From $Telos^{(R)}$ stress x-ray evaluation, difference from the opposite knee was improved average 13.2 mm{\pm}5.8 (range: 6~21 mm) to average $3.4\;mm{\pm}2.8$ (range: 0~11 mm) after operation (p<0.05). The femoral and tibial tunnel were widened by 18.7% and 9.6% in the AP view and 12.4% and 8.5% in the lateral view, respectively (p<0.05). However, any statistic significance was not observed between bone tunnel expansion and knee joint functions (p>0.05). Conclusion: An ACL reconstruction with tibialis allograft using Hybrid femoral fixation and $Retroscrew^{(R)}$ enabled anatomical fixation of the graft tendon with satisfactory clinical results.

• Journal of Chest Surgery
• /
• v.37 no.1
• /
• pp.1-10
• /
• 2004

Background: Currently, the cardiopulmonary machine with non-pulsatile pumps, which are low in internal circuit pressure and cause little damage to blood cells, is widely used. However, a great number of experimental studies shows that pulsatile perfusions are more useful than non-pulsatile counterparts in many areas, such as homodynamic, metabolism, organ functions, and micro-circulation. Yet, many concerns relating to pulsatile cardiopulmonary machines, such as high internal circuit pressure and blood cell damage, have long hindered the development of pulsatile cardiopulmonary machines. Against this backdrop, this study focuses on the safety and effectiveness of the pulsatile cardiopulmonary machines developed by a domestic research lab. Material and Method: The dual-pulsatile cardiopulmonary bypass experiment with total extracorporeal circulation was conducted on six calves, Extracorporeal circulation was provided between superior/inferior vena cava and aorta. The membrane oxygenator, which was placed between the left and right pumps, was used for blood oxygenation. Circulation took four hours. Arterial blood gas analysis and blood tests were also conducted. Plasma hemoglobin levels were calculated, while pulse pressure and internal circuit pressure were carefully observed. Measurement was taken five times; once before the operation of the cardiopulmonary bypass, and after its operation it was taken every hour for four hours. Result: Through the arterial blood gas analysis, PCO2 and pH remained within normal levels. PO2 in arterial blood showed enough oxygenation of over 100 mmHg. The level of plasma hemoglobin, which had total cardiopulmonary circulation, steadily increased to 15.87 $\pm$ 5.63 after four hours passed, but remained below 20 mg/㎗. There was no obvious abnormal findings in blood test. Systolic blood pressure which was at 97.5$\pm$5.7 mmHg during the pre-circulation contraction period, was maintained over 100 mmHg as time passed. Moreover, diastolic blood pressure was 72.2 $\pm$ 7.7 mmHg during the expansion period and well kept at the appropriate level with time passing by. Average blood pressure which was 83$\pm$9.2 mmHg before circulation, increased as time passed, while pump flow was maintained over 3.3 L/min. Blood pressure fluctuation during total extracorporeal circulation showed a similar level of arterial blood pressure of pre-circulation heart. Conclusion: In the experiment mentioned above, pulsatile cardiopulmonary machines using the doual-pulsatile structure provided effective pulsatile blood flow with little damage in blood cells, showing excellence in the aspects of hematology and hemodynamic. Therefore, it is expected that the pulsatile cardiopulmonary machine, if it becomes a standard cardiopulmonary machine in all heart operations, will provide stable blood flow to end-organs.

• Journal of Trauma and Injury
• /
• v.21 no.1
• /
• pp.28-35
• /
• 2008

Purpose: This study was conducted to examine the clinical significance IV-contrasted helical abdomen computed tomography (CT) as a diagnostic screening tool to evaluate hollow viscus injury in blunt abdominal trauma patients. Methods: This is a retrospective study encompassing 108 patients, presenting to Korea University Medical Center (KUMC) Emergency Department (ED) from January 2007 to December 2007, with an initial CT finding suggestive of intra-abdominal injury. An initial non-enhanced abdomen CT was taken, followed by an enhanced CT with intravenous contrast. Patients' demographic data, as well as the mechanisms of injury, were inquired upon and obtained, initial diagnosis, as dictated by specialized radiologists, were added to post-operational (post-OP) findings and to additional CT findings acquired during their hospital stays, and all were combined to arrive at final diagnosis. Initial CT findings were further compared with the final diagnosis, yielding values for sensitivity, specificity, and accuracy, as well as positive and negative predictive values. Patients were further divided into two groups, namely, those that underwent operational intervention and those that did not. The initial CT findings of each group were subsequently compared and analyzed. Results: Initial CT scans revealed abnormal findings in a total of 212 cases - solid organ injuries being the most common finding, as was observed in 97 cases. Free fluid accumulation was evident in another 69 cases. Based on the CT findings, 77 cases (71.3%) were initially diagnosed as having a solid organ injury, 20 cases (18.5%) as having a combined (solid organ + hollow viscus) injury, and 11 cases (10.2%), as having an isolated hollow viscus injury. The final diagnosis however, were somewhat different, with only 67 cases (62.0%) attributed to solid organ injury, 31 cases (28.7%) to combined injury (solid + hollow), and 10 cases (9.3%) to hollow viscus injury. The sensitivity (CI 95%) of the initial helical CT in diagnosing hollow viscus injury was 75.6%, and its specificity was 100%. The accuracy in diagnosing hollow viscus injury was also meaningfully lower compared to that in diagnosis of solid organ injury. Among patients initially diagnosed with solid organ injuries, 10 patients (2 from follow-up CT and 8 from post-OP finding) turned out to have combined injuries. A total of 38 patients underwent an operation, and the proportion of initial CT findings suggesting free air, mesenteric hematoma or bowel wall thickening turned out to be significantly higher in the operation group. Conclusion: Abdominal CT was a meaningful screening test for hollow viscus injury, but the sensitivity of abdominal CT was significantly lower in detecting hollow viscus injury as compared to solid organ injury. This calls for special consideration and careful observation by the ED physicians when dealing with cases of blunt abdominal trauma.

• Journal of Chest Surgery
• /
• v.37 no.10
• /
• pp.817-826
• /
• 2004

Background: Several studies have demonstrated that conventional hypothermic cardiopulmonary bypass (CPB) causes cellular injury, abnormal responses in peripheral vascular beds and increased postoperative bleeding, whereas normothermic CPB provides protection of the hypothermic-induced effects and better cardiac recovery. The present study was prospectively performed to compare the effects of normothermic CPB to those of hypothermic CPB on the inflammatory and hematologic responses during cardiac surgery. Material and Method: Thirty-four adult patients scheduled for elective cardiac surgery were randomly assigned to hypothermic CPB (nasopharyngeal temperature $26～28^{\circ}C,$ n=17) or normothermic CPB (nasopharyngeal $temperature>35.5^{\circ}C,$ n=17) group. In both groups, cold $(4^{\circ}C)$ crystalloid cardioplegia was applied for myocardial protection. Blood samples were drawn from radial artery before (Pre-CPB), 10 minutes after starting (CPB-10) and immediately after ending (CPB-OFF) CPB. Total leukocyte and platelet counts, interleukin-6 (IL-6) level(expressed as percent to the baseline of Pre-CPB), D-dimer level, protein C and protein S activity were measured with the blood samples. The amount of bleeding for postoperative 24 hours and blood transfusion after operation were also assessed. All parameters were compared between the two groups. Result: The total leukocyte counts $(10,032\pm65/mm^3)$ and the increased ratio of IL-6 $(353\pm7.0%)$ at CPB-OFF in the normothermic group were higher than that $(7,254\pm48/mm^3$ and $298\pm7.3%)$ of the hypothermic group(p=0.02 and p=0.03). In the normothermic group, protein C activity $(32\pm3.8%)$ and protein S activity $(35\pm4.1%)$ at CPB-OFF were significantly lower than that $(45\pm4.3%$ and $51\pm3.8%)$ of the hypothermic group (p=0.04 and p=0.009). However, there were no differences in platelet counts and D-dimer concentration. In the normothermic group, the amount of bleeding for postoperative 24 hours $(850\pm23.2$ mL) and requirements for blood transfusion after operation such as packed cell $(1,402\pm20.5$ mL), fresh frozen plasma $(970\pm20.8$ mL) and platelet $(252\pm6.4$ mL) were higher than that $(530\pm21.5$ mL, $696\pm15.7$ mL, $603\pm18.2$ mL and $50\pm0.0$ mL) of the hypothermic group. Conclusion: These results indicate that normothermic CPB with cold crystalloid cardioplegia was associated with higher increase in inflammatory response, hemostatic abnormalities and postoperative bleeding problem than moderate hypothermic CPB.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.9 no.2
• /
• pp.138-147
• /
• 1998

Authors surveyed intrafamilial child sexual abuse in the children under 15years old in clinical. We sent the semi-structured child sexual abuse questionnaires to 7055 board certified pediatrics, obstetrics and gynecology, family medicine and emergency medicine. Total respondents were 1205. The results from these respondents were as follows. 1) The numbers of respondents who have had the experience of treating victims of intrafamilial child sexual abuses were 157(13.0% of total respondents). 2) Among the perpetrators, 58(36.9%) were siblings and 32(20.4%) 26(16.6%) were step-fathers, and respectively. The most common age bracket was 10s(39.5%), and the next was 40s and 50s (33.7%) Almost all(98.7%) of the perpetrators were male. 3) The mean age of victims was $12.1{\pm}3.3$ years old, and all of the victims were female, and the number of victims who had previous mental or physical handicaps and behavior problems were 5(3.2%) and 8(5.1%) respectively. 4) The ways by which intrafamilial child sexual abuses were found were abnormal behaviors 45(28.7%), victim's own report 40(25.5%), pregnancy 18(11.5%), pain complaint 13(8.3%), other person's report 13(8.3%), and detection during examination 12(7.6%). 5) Time lags between intrafamilial child sexual abuses and hospital visits were after 1 month 97(61.8%), from 1 day to 1 week 29(18.5%), within 1 day 21(13.4%), and from 1 week to 1 month 10(6.4%). 6) Physical complications were perineal wound 93(59.2%), hymen rupture 90(57.3%), pregnancy 68(43.3%), wound of other part of body 11(7.0%), and sexually transmitted disease 4(4.5%). 7) Treatment for victims were discharge 92(58.6%), admission, operation or transfer to a bigger hospital 25(15.9%), psychiatry consult 19(12.1%), report to police(10.9%) and social work consult 3(1.9%). These results suggest that considerable numbers of physicians have had the experience of treating victims of intrafamilial child sexual abuses, and intrafamilial child sexual abuses are the major medical as well as social issue in children in Korea.

• Journal of Bio-Environment Control
• /
• v.22 no.4
• /
• pp.371-377
• /
• 2013

The government has been carrying out a project for supporting the rain shelter for hot pepper as part of measures stabilizing the demand and supply of hot pepper since 2012. However, the eaves height of single-span plastic greenhouses extensively used in farms is low, which are inappropriate for the rainproof cultivation of hot pepper. This study attempted to develop single-span plastic greenhouses which are structurally safe and have the dimensions suitable for the rainproof cultivation of hot pepper as well. The structure status of plastic greenhouses and restructuring wishes of 56 rainproof cultivation farms nationwide were investigated to set up the width and height of the plastic greenhouses. 53% of the plastic greenhouses currently in operation had a width of under 7 m and 64% of their eaves had a height of 1.5 m or less, which accounted for the highest rate. Mostly the width of 7.0 m was desired for the greenhouses and the height of 2.0 m for their eaves, so these values were chosen as the dimensions for the singlespan plastic greenhouses. After an analysis of their structural safety while changing the specifications of the rafter pipe in various ways, 5 kinds of models were suggested considering the frame ratio and installation costs. The 12-Pepper-1 model is a developed single-span plastic greenhouse for hot pepper in which a ${\emptyset}42.2{\times}2.1t$ rafter pipe is installed at an interval of 90cm and the models of 12-Pepper-2 through 5 are the other developed ones in which a ${\emptyset}31.8{\times}1.5t$ rafter pipe is installed at intervals of 60 cm, 70 cm, 80 cm and 90 cm, respectively. As a result of an analysis of economic feasibility of 12-Pepper-2 compared to 10-Single-3 in the notification of the Ministry for Food, Agriculture, Forestry and Fisheries, it turned out that there would be an increase in profits by about 1.2 million won based on one building of a greenhouse sized 672 $m^2$.