• Journal of Korean Society of Water and Wastewater
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• v.34 no.1
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• pp.35-43
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• 2020

Turbidity has various effects on the water quality and ecosystem of a river. High turbidity during floods increases the operation cost of a drinking water supply system. Thus, the management of turbidity is essential for providing safe water to the public. There have been various efforts to estimate turbidity in river systems for proper management and early warning of high turbidity in the water supply process. Advanced data analysis technology using machine learning has been increasingly used in water quality management processes. Artificial neural networks(ANNs) is one of the first algorithms applied, where the overfitting of a model to observed data and vanishing gradient in the backpropagation process limit the wide application of ANNs in practice. In recent years, deep learning, which overcomes the limitations of ANNs, has been applied in water quality management. LSTM(Long-Short Term Memory) is one of novel deep learning algorithms that is widely used in the analysis of time series data. In this study, LSTM is used for the prediction of high turbidity(>30 NTU) in a river from the relationship of turbidity to discharge, which enables early warning of high turbidity in a drinking water supply system. The model showed 0.98, 0.99, 0.98 and 0.99 for precision, recall, F1-score and accuracy respectively, for the prediction of high turbidity in a river with 2 hour frequency data. The sensitivity of the model to the observation intervals of data is also compared with time periods of 2 hour, 8 hour, 1 day and 2 days. The model shows higher precision with shorter observation intervals, which underscores the importance of collecting high frequency data for better management of water resources in the future.

• Journal of Chest Surgery
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• v.25 no.7
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• pp.685-692
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• 1992

In spite of multiple technical advances, large amount of homologous blood transfusions usually required for open heart surgery. Because the complications associated with transfusion are increased as the number of homologous transfusion increase, especially as transfusion related acquired immunodeficiency syndrome has appeared in recent years, such risks have stimulated recent interest in the use of autologous blood. This is a report concerning 23 consecutive adult autologous donors[autologous group] who had elective cardiac surgery at the Yonsei Cardiovascular Center, Yonsei University College of Medicine, from march, 1990 to august, 1991. A similar group of 23 patients operated during the same periods without autologous blood donation was used for comparison [control group] to investigate the effect of predonated autologous blood in decreasing the need of homologous transfusion and to investigate predonation related adverse effect. Autologous group consisted of 15 men and 8 women. Control group consisted of 7 men and 16 women. There were no significant differences in mean age, hemoglobin, hematocrit, RBC count, platelet count and prothrombin time on admission between the two groups. The mean autologous blood donation in autologous group was 2.2 units. In 10[43.5%] of the 23 atuologous group patients, no homologous RBC products transfusion was required. However, all patients required homologous transfusion in control group. In autologous group, patients required less homologous RBC products than control patients[2.1 units versus 5.3 units; p<0.001]. There were no significant differences in hemoglobin, hematocrit, RBC count and platelet count between the two groups before discharge. There were no serious complications related to preoperative blood donation, although 3 patients complained of mild dizziness during donation We conclude that preoperative autologous predonation of blood is a safe and effective method for reducing homologous transfusion and is recomended in all patients undergoing elective cardiac surgery except limited contraindications such as severe aortic valve stenosis or unstable angina pectoris.

• Journal of Korea Water Resources Association
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• v.39 no.1 s.162
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• pp.35-46
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• 2006

In this study, we proposed a layout of the integrated decision support system in order to prevent the contamination and to manage risk in water supply networks for safe and smooth water supply. We evaluated the priority of risk factors to detect anomaly in water supply networks using PROMETHEE and ANP techniques, which are applied to various Multi-Criteria Decision Making area in Europe and America. To develop the model, we selected pH, residual chlorine concentration, discharge, hydraulic pressure, electrical conductivity, turbidity, block leakage and water temperature as the key data item. We also chose pipe corrosion, pipe burst and water pollution in pipe as the criteria and then we present the results of PROMETHEE and ANP analysis. The evaluation results of the priority of risk factors in water supply networks will provide basic data to establish a contingency plan for accidents so that we can establish the specific emergency response procedures.

• Fire Science and Engineering
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• v.18 no.1
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• pp.18-23
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• 2004

This paper describes the minimum ignition limits for propane-air 5.25 Vol.% mixture gases in low voltage inductive circiuts. The improved effects on the ignition limit are studied by parallel safety components(resistors) for propane-air 5.25 Vol.% mixture gas in low voltage inductive circuits. The experimental devices used in this test are the IEC type spark ignition test apparatus. The minimum ignition limits are controlled by the values of current in inductive circuit. Energy supplied from electric source is first accumulated at the inductance, it's extra energy is working as ignition source of the explosive gas. The improved effects on the ignition limit are respectively obtained as the maximum rising rate of 330% by composing parallel circuits between inductance and resistor as compared with disconnecting inductance with the safety components. The more values of inductance increase the higher improved effects of ignition limit rise. The less values of resistor the higher improved effects of ignition limit rise. It is considered that the result can be used for not only data for researches and development of intrinsically safe explosion-proof machines which are applied equipment and detectors used in dangerous areas but also for datum for its equipment tests.

• Journal of Korean Neurosurgical Society
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• v.39 no.6
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• pp.413-418
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• 2006

Objective : The objective of this study is to evaluate and compare the clinical results between classical open surgery and percutaneous endoscopic lumbar discectomy[PELD] in cases of extraforaminal lumbar disc herniation. Methods : We obtained the clinical data from 47 patients with extraforaminal lumbar disc herniations who underwent the open paramedian muscle-splitting approach or percutaneous endoscopic lumbar discectomy[PELD] between January 2001 and February 2004. This study consisted of patients with soft disc extraforaminal herniations. The patients were assessed with the visual analogue scale[VAS] and MacNab's criteria before surgery, just before discharge, and postoperative 1 year. Results : There were 25 cases in the open surgery group and 22 cases in the PELD group. The average operating time was $78{\pm}36.71\;min$ in the PELD group and $110{\pm}29.68\;min$ in the open surgery group. The mean hospital stay was $2.73{\pm}2.62$ days in the PELD group and $7.68{\pm}2.59$ days in the open surgery group. VAS decreased from $8.34{\pm}0.66$ to $1.29{\pm}2.27$ in the PELD group and from $8.40{\pm}1.40$ to $1.70{\pm}1.72$ in the open surgery group at the one-year follow-up. The success rate of PELD was 86.4%, compared with 80.0% for open surgery. However, there were no statistically significant difference between two groups for success rate and VAS. Conclusion : Although the success rates were similar in both groups, PELD is less invasive, faster, and safe procedure than open surgery for extraforaminal disc herniation in selected patients.

• Journal of Korean Neurosurgical Society
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• v.45 no.6
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• pp.360-368
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• 2009

Objective : The objectives of this study were to analyze the recanalization rates and outcomes of multimodal therapy that consisted of sequential intravenous (IV)/intra-arterial (IA) thrombolysis, mechanical thrombolysis including mechanical clot disruption using microcatheters and microwires, balloon angioplasty, and stenting for acute ischemic stroke, and to evaluate the prognostic factors related to the outcome. Methods : Fifty patients who were admitted to the hospital within 8 hours from ischemic symptom onset were retrospectively analyzed. Initial IV thrombolysis and subsequent cerebral angiography were performed in all patients. If successful recanalization was not achieved by IV thrombolysis, additional IA thrombolysis with mechanical thrombolysis, including balloon angioplasty and stenting, were performed. The outcomes were assessed by the National Institute of Health Stroke Scale (NIHSS) change and modified Rankin scale (mRS) and prognostic factors were analyzed. Results : Successful recanalization was achieved in 42 (84%) of 50 patients, which consisted of 8 patients after IV thrombolysis, 19 patients after IA thrombolysis with mechanical clot disruption, and 15 patients after balloon angioplasty or stenting. Symptomatic hemorrhage occurred in 4 (8%) patients. Good outcomes were achieved in 76% and 70% of patients upon discharge, and 93% and 84% of patients after 3 months according to the NIHSS change and mRS. The initial clinical status, recanalization achievement, and presence of symptomatic hemorrhage were statistically related to the outcomes. Conclusion : Multimodal therapy may be an effective and safe treatment modality for acute ischemic stroke. Balloon angioplasty and stenting is effective for acute thrombolysis, and produce higher recanalization rates with better outcomes.

• Journal of Korean Neurosurgical Society
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• v.45 no.6
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• pp.350-354
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• 2009

Objective : The purpose of this study was to analyze the clinical outcome of 75 consecutive patients with cervical carotid artery stenosis and who were treated by carotid artery stenting (CAS) only. Methods : From February 2003 to June 2008, there were 78 stents placed in 75 symptomatic patients (mean age : 67.3 years); 69 patients had carotid stenosis ${\geq}70%$, and 6 patients had asymptomatic stenosis ${\geq}80%$. No carotid endarterectomy (CEA) was performed during the same period. The patients were clinically followed-up for a mean of 20.1 months. Results : The procedures were technically successful in all cases. Three (3.8%) patients had procedure-related complications. During the 30-day postprocedural period, there were no restenosis or major stroke. Minor stroke was noticed in 3 (3.8%) patients and 1 (1.3%) of the 75 patients suddenly expired 2 days after discharge. There were no new neurological symptoms that developed during the clinical follow-up period. The results of our series were not inferior to those the previously published in CAS studies, and in fact they were better. Conclusion : Our results suggest that CAS may be safe and useful for the treatment of cervical carotid artery stenosis when it is used as the first line treatment in those institutions that lack enough experience with CEA.

• Journal of The Korean Dental Society of Anesthesiology
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• v.12 no.2
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• pp.75-91
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• 2012

Background: Dental sedation reduces fear and phobia during dental treatment and helps patients get quality treatment by inducing adequate consciousness control. Propofol has recently grabbed the spotlight, but no meta-analysis for efficacy and safety of propofol in dentistry has yet been performed. Thus, the purpose of this study was to perform meta-analysis to verify the efficacy and safety of propofol for use in dental sedation. Methods: Articles published between 1980 and 2010 were searched in the web sites, journals and medical database including The Cochrane Library, MEDLINE and EMBASE. And a total of 22 studies were selected among the randomized controlled trials (RCTs) that compared the use of propofol with other sedatives (control group). The data was collected from these studies and meta-analysis for efficacy and safety was performed using Comprehensive Meta-Analysis 5.0 (CMA 5.0). Results: The patient recovered significantly faster and discharged significantly earlier in the propofol group (SMD = -1.442, P < 0.001). The satisfaction of patient and that of operator was higher in the propofol group (P < 0.05). The incidence of arrhythmia and apnea/ hypoventilation was significantly lower in the propofol group (OR = 0.071, P < 0.05), and there was no significant difference in the other side effects. On the level of sedation, although the sedation score was significantly lower in the propofol group (SMD = -0.430, P < 0.05). Conclusions: The present analysis showed that the use of propofol resulted in high satisfaction levels on the part of the patients and operators, a shorter recovery time, and faster hospital discharge. The incidence of complications, however, was lower in the propofol groups or not much different between the propofol and control groups. Thus, the adequate use of propofol in dentistry is believed to be helpful for the effective and safe sedation of the patients.

• Journal of Chest Surgery
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• v.54 no.5
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• pp.383-388
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• 2021

Background: Achieving external access to and manual occlusion of the left atrial appendage (LAA) during minimally invasive mitral valve surgery (MIMVS) through a small right thoracotomy is difficult. Occlusion of the LAA using an epicardial closure device seems quite useful compared to other surgical techniques. Methods: Fourteen patients with atrial fibrillation underwent MIMVS with concomitant surgical occlusion of the LAA using double-layered endocardial closure stitches (n=6, endocardial suture group) or the AtriClip Pro closure device (n=8, AtriClip group) at our institution. The primary safety endpoint was any device-related adverse event, and the primary efficacy endpoint was successful complete occlusion of blood flow into the LAA as assessed by transthoracic echocardiography at hospital discharge. The primary efficacy endpoint for stroke reduction was the occurrence of ischemic or hemorrhagic neurologic events. Results: All patients underwent LAA occlusion as scheduled. The cardiopulmonary bypass and aortic cross-clamp times in the endocardial suture group and the AtriClip group were 202±39 and 128±41 minutes, and 213±53 and 136±44 minutes, respectively (p=0.68, p=0.73). No patients in either group experienced any device-related serious adverse events, incomplete LAA occlusion, early postoperative stroke, or neurologic complication. Conclusion: Epicardial LAA occlusion using the AtriClip Pro during MIMVS in patients with mitral valve disease and atrial fibrillation is a simple, safe, and effective adjunctive procedure.

• Annals of Coloproctology
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• v.34 no.6
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• pp.317-321
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• 2018

Purpose: We evaluate the role of transanal tube drainage (TD) as a conservative treatment for patients with anastomotic leakage (AL). Methods: Patients treated for AL who had undergone a low or an ultralow anterior resection with colorectal or coloanal anastomosis for the treatment of rectal cancer between January 2013 and January 2017 were enrolled in this study. The data were collected prospectively and analyzed retrospectively. The primary outcomes were the diagnosis and the management of AL. Results: Two hundred thirteen consecutive patients, 122 males and 91 females, were included. The mean age was $66.91{\pm}11.15years$, and the median body mass index was $24kg/m^2$ (range, $20-35kg/m^2$). The median tumor distance from the anal verge was 8 cm (range, 4-12 cm). Ninety-three patients (44%) received neoadjuvant therapy for nodal disease and/or locally advanced rectal cancer. Only 13 patients (6%) developed AL. Six patients developed subclinical AL as they had a defunctioning ileostomy at the time of the initial procedure. They were treated conservatively with TD under endoscopic guidance in the endoscopy unit and received intravenous antibiotics. Six weeks after discharge, these 6 patients underwent follow-up flexible sigmoidoscopy which showed a completely healed anastomotic defect with no residual stenosis. Seven patients developed a clinically significant AL and required reoperation with pelvic abscess drainage and Hartmann colostomy formation. Conclusion: These results suggest that TD for management of patients with AL is safe, cheap, and effective. Salvaging the anastomosis will help decrease the need for Hartmann colostomy formation. Proper patient selection is important.