• The Journal of Engineering Geology
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• v.24 no.2
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• pp.283-295
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• 2014

Groundwater monitoring wells are important to maintain their performance for long term monitoring. The monitoring wells with extensive internal incrustation by clay adsorption were selected for this study. The performance of these monitoring wells was improved by pump washing, tube replacements for dedicated samplers, and well surging. After each improvement, the Mg, Mn, and Zn concentrations were increased. The results show that under these conditions, the monitoring wells must be carefully inspected at least once a year. Even in the case of no abnormal phenomenon like as internal incrustation, the monitoring wells need to be serviced at least once every four to five years to guarantee that they are effectively monitoring groundwater quality.

• Advances in pediatric surgery
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• v.10 no.2
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• pp.92-98
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• 2004

The history of esophageal replacement in infants or children is the history of development of various kinds of alternative conduits such as stomach, colon, and small bowel. The gastric tube has been the most widely used conduit. From January 1988 to May 2003, 23 esophageal replacements with gastric tube were performed at the Department of Pediatric Surgery, Seoul National University Childrens Hospital. Statistical analysis was performed using Windows SPSS11.0 Pearson exact test. There were Gross type A(n=10), type B(n=1), type C(n=11), type D(n=1). Ten patients who had long gap esophageal atresia (type A-8, type B-1, type C-1) and 13 patients (type A 2, type C-10, type D-1) who had stenosis, leakage, recurred tracheoesophageal fistula, and esophagocutaneous fistula after previous corrective operations, had esophageal replacement with gastric tube. Mean follow-up periods were 4 year 2 months (7 months-15 year 1 month). There were postoperative complications including GERD in 16 (69.6 %), leakages in 7 (30.4 %), diverticulum at anastomosis in 2 (8.7 %), anastomosis site stenosis in 4 (17.3 %), and distal stenosis of the gastric tube in 1 (4.3 %). There was no statistical significance between operation types and postoperative leakage and gastroesophageal reflux. In conclusion, esophageal replacement with gastric tube may be a useful surgical option in esophageal atresia with long gap and esophageal atresia complicated by previous corrective operation.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1288-1297
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• 2016

This study proposes a single-stage light-emitting diode (LED) tube lamp driver with input-current shaping for T8/T10-type fluorescent lamp replacements. The proposed AC-DC LED driver integrates a dual-boost converter with coupled inductors and a half-bridge series-resonant converter with a bridge rectifier into a single-stage power conversion topology. This paper presents the operational principles and design considerations for one T8-type 18 W-rated LED tube lamp with line input voltages ranging from 100 V rms to 120 V rms. Experimental results for the prototype driver show that the highest power factor (PF = 0.988), lowest input current total harmonic distortion (THD = 7.22%), and highest circuit efficiency (η = 92.42%) are obtained at an input voltage of 120 V. Hence, the proposed driver is feasible for use in energy-efficient indoor lighting applications.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.1
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• pp.8-13
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• 2016

Public institutions should replace their luminaires with LED lighting by 2020 to save energy. Because the LED lighting installation rate in schools has not yet reached the legal goal, the ESCO program feasibility was investigated. The amount of electricity used, electric rates, times of use in classrooms and fluorescent lighting maintenance costs etc., as well as the elements of lighting maintenance were analyzed. In the case of schools, the lamp usage time was so short that the ESCO projects with only energy savings were impossible. In order to execute the ESCO projects, the maintenance cost savings by replacing an existing luminaire should be considered and the introduction of the relatively cheaper tube type LED lamp than the flat type LED luminaire was required.

• Korean Journal of Community Nutrition
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• v.3 no.5
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• pp.729-738
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• 1998

In order to investigate the types of enteral nutrition formulas currently used in hospitals and evaluate and categorize the commercially prepared enteral nutrition formulas formulas available in the domestic market, we asked dietitians working in 6 hospitals in Seoul to complete the questionnaire and obtained compositional characteristics of 12 commercially prepared enteral nutrition formulas. The average proportion of patients receiving the commercially prepared enteral nutrition formulas(60.6%) was greater than that of patients receiving the in-hospital preparations(31.9%). In the group of patients receiving the in-hospital prepared formulas, the enteral feeding was mainly administered orally, whereas, in the group of patients receiving the commercially prepared formulas, tube feeding was the primary route of formula administration. In both groups, however, a greater proportion of patients received the formulas as total replacements of their meals and for the purpose of dietary supplementation. On the basis of major criteria for evaluation of the commercially prepared enteral nutrition formulas, the 6 products out of the 9 nutritionally complete products formulated for the purpose of dietary supplementation were grouped into the same category(standard protein, caloric density of 1kcal/ml, and tube/oral), so they were considered therapeutically comparable. However, the remaining 3 products were different in protein content(high protein) or route of administration(tube only). Of the 3 nutritionally complete products formulated specifically for the purpose of dietary therapy, 2 products were formulated for patients with renal disease, and the one product was formulated for diabetic patients. Therefore, the data in this study showed that the commercially prepared enteral nutriton formulas became an important part of the enteral nutrition for hospitalized patients in Korea, but the domestic market has not yet generated a wide variety of the formulas, not providing many choices for clinicians to manage the diets for their patients. The results of this study would be helpful for clinicians in choosing appropriate products for their patients, for manufactures in developing new products, and for regulatory authorities to establish the regulation for the broad group of heterogeneous products that are marketed and will be developed as medical foods. In addition, the process of maintaining the categories for evaluation of the commercially prepared enteral nutrition formulas should be dynamic because new products may not reasonably fit any of the existing categories.

• Journal of Chest Surgery
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• v.21 no.3
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• pp.497-509
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• 1988

Current therapy of aortic dissections remains unstandardized because of the relative rarity of these catastrophic events and conflicting reported results of various therapeutic strategies. Hence, we reviewed our current results and planned to purify our method of interpretation of results and so, to standardize therapeutic managements. This study comprised unselected, consecutive 27 patients with aortic dissections who were operated at Seoul National University Hospital from Jan 1983 to March 1988. The results from analysis of their preoperative, operative and postoperative finding were as follows: 1] 7 patients had acute type A, 14 had chronic type A, 4 had acute type B, and 2 had chronic type B. 2] The causes of dissections were unclear, but 8 patients had Marfan`s syndromes, 2 had previous operative histories on cardiovascular systems and 2 had congenital heart diseases. 3] Multiple preoperative variables were found to correlate significantly with operative mortality and complications. The prevalences of such preoperative major complicating factors were significantly more frequent in acute than chronic [P < 0.05] and type A than type B [P < 0.01]. 4] Operations were performed according to the type of the dissections and whether it was acute or chronic. Usually dacron tube graft replacements were performed[25/26]. Intraluminal sutureless graft replacement was performed in 11 patients. Of the 14 patients with combined aortic regurgitation, concomitant aortic valve resuspension in 4, seperative aortic valve replacement in 1, and aortic valve replacement with coronary reimplantation were performed in 9 patients. 2 patients had concomitant arch vessel managements. 5] Over-all operative mortality rate was 33% and 54% for acute type A, 25% for acute type B, 29% for chronic type A, 0% for chronic type B respectively. The main causes of operative mortality were cardiovascular complications [mainly CPB-weaning failure] in acute cases and hemorrhagic complications in chronic cases.

• Journal of Chest Surgery
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• v.32 no.7
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• pp.621-627
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• 1999

Background: Sixty five cases with congenitally corrected transposition of the great arteries (CCTGA) indicated for biventricular repair were operated on between 1984 and september 1998. Comparison between the results of the conventional(classic) connection(LV-PA) and the anatomic repair was done. Material and Method: Retrospective review was carried out based on the medical records of the patients. Operative procedures, complications and the long-term results accoding to the combining anomalies were analysed. Result: Mean age was 5.5$\pm$4.8 years(range, 2 months to 18years). Thirty nine were male and 26 were female. Situs solitus {S,L,L} was in 53 and situs inversus{I,D,D} in 12. There was no left ventricular outflow tract obstruction(LVOTO) in 13(20%) cases. The LVOTO was resulted from pulmonary stenosis(PS) in 26(40%)patients and from pulmonary atresia(PA) in 26(40%) patients. Twenty-five(38.5%) patients had tricuspid valve regurgitation(TR) greater than the mild degree that was present preoperatively. Twenty two patients previously underwent 24 systemic- pulmonary shunts previously. In the 13 patients without LVOTO, 7 simple closure of VSD or ASD, 3 tricuspid valve replacements(TVR), and 3 anatomic corrections(3 double switch operations: 1 Senning+ Rastelli, 1 Senning+REV-type, and 1 Senning+Arterial switch opera tion) were performed. As to the 26 patients with CCTGA+VSD or ASD+LVOTO(PS), 24 classic repairs and 2 double switch operations(1 Senning+Rastelli, 1 Mustard+REV-type) were done. In the 26 cases with CCTGA+VSD+LVOTO(PA), 19 classic repairs(18 Rastelli, 1 REV-type), and 7 double switch operations(7 Senning+Rastelli) were done. The degree of tricuspid regurgitation increased during the follow-up periods from 1.3$\pm$1.4 to 2.2$\pm$1.0 in the classic repair group(p<0.05), but not in the double switch group. Two patients had complete AV block preoperatively, and additional 7(10.8%) had newly developed complete AV block after the operation. Other complications were recurrent LVOTO(10), thromboembolism(4), persistent chest tube drainage over 2 weeks(4), chylothorax(3), bleeding(3), acute renal failure(2), and mediastinitis(2). Mean follow-up was 54$\pm$49 months(0-177 months). Thirteen patients died after the operation(operative mortality rate: 20.0%(13/65)), and there were 3 additional deaths during the follow up period(overall mortality: 24.6%(16/65)). The operative mortality in patients underwent anatomic repair was 33.3%(4/12). The actuarial survival rates at 1, 5, and 10 years were 75.0$\pm$5.6%, 75.0$\pm$5.6%, and 69.2$\pm$7.6%. Common causes of death were low cardiac output syndrome(8) and heart failure from TR(5). Conclusion: Although our study could not demonstrate the superiority of each classic or anatomic repair, we found that the anatomic repair has a merit of preventing the deterioration of tricuspid valve regurgitations. Meticulous selection of the patients and longer follow-up terms are mandatory to establish the selective advantages of both strategies.