A Study on Construction of Antenna Measurement Environment

In this thesis, a program was presented for antenna measurement with GUI technique. In order to obtain the accuracy of measurement results and the reduction of the measurement time, the measurement equipments are automatically controlled by a proposed program. These equipments are connected by GPIB cable. The measured data are also normalized automatically by the proposed program. This software provides visually the measured results such as a normalized radiation pattern and antenna gain. As a result, It was confirmed that, the proposed antenna measurement program showed a good performance. In addition, measurement results of sonobuoy transmitter was presented as an example of antenna measurement. A measurement program for sonobuoy transmitter using GUI technique was developed, because sonobuoy transmitter should keep the strict military specification. This program offers automatic normalization of measured data and shortens measurement time. In Addition, the SWR and the radiation patterns and characteristics of sonobuoy transmitter were measured and estimated. Also the drop out, power density and spurious radiation of sonobuoy transmitter were measured and estimated. As a result, sonobuoy transmitter satisfied the military specification and it showed a good performance.Abbreviations iii Abstract iv 제 1 장 서 론 1 1.1 연구배경 1 1.2 연구목적 및 필요성 1 1.3 연구목표 2 제 2 장 안테나 측정 환경 3 2.1 전파암실의 안테나 측정 시스템 구성 3 2.2 안테나 측정 알고리즘 5 2.2.1 방사패턴 측정 프로그램 5 2.2.2 이득 측정 프로그램 10 제 3 장 제작된 프로그램을 이용한 안테나 측정 13 3.1 안테나 방사패턴 측정 13 3.2 안테나 이득 측정 14 제 4장 Sonobuoy 송신기의 측정 19 4.1 Sonobuoy 송신기의 개요 19 4.2 Sonobuoy 송신기의 측정환경 21 4.2.1 Sonobuoy 송신기의 측정시스템 구성 21 4.2.2 Sonobuoy 안테나의 구조 24 4.2.3 Sonobuoy 송신기 측정 프로그램 26 4.3 Sonobuoy 송신기의 특성 평가 32 4.3.1 방사패턴 34 4.3.2 출력강하 36 4.3.3 전력밀도 38 4.3.4 Spurious 방사 41 제 5 장 결 론 43 참고 문헌 4

Chylothorax after Surgery for Congenital Cardiac Disease: A Prevention and Management Protocol

Background: Chylothorax after congenital heart surgery is not an uncommon complication, and it is associated with significant morbidity. However, consensus treatment guidelines are lacking. To improve the treatment outcomes of patients with postoperative chylothorax, we implemented a standardized management protocol at Severance Hospital in September 2014. Methods: A retrospective review of patients treated at a single center was done. All corrective and palliative operations for congenital heart disease performed at our institution between January 2008 and April 2018 were reviewed. The incidence and treatment outcomes of postoperative chylothorax were analyzed. Results: The incidence of chylothorax was 1.9%. Sixty-one percent of the patients could be managed with a low-fat diet, while 28% of the patients required complete restriction of enteral feeding. Thoracic duct embolization was performed in 2 patients and chest tube drainage decreased immediately after the procedure. No patient required thoracic duct ligation or pleurodesis. After implementation of the institutional management protocol, the number of chest tube drainage days decreased (median, 24 vs. 14 days; p=0.45). Conclusion: Implementing a strategy to reduce postoperative chylothorax resulted in an acceptable incidence of postoperative chylothorax. Instituting a clinical practice protocol helped to curtail the treatment duration and to decrease the requirement for surgical treatment. Image-guided embolization of the thoracic duct is an effective treatment for postoperative chylothorax.ope

Concomitant Right Ventricular Outflow Tract Cryoablation during Pulmonary Valve Replacement in a Patient with Tetralogy of Fallot

A 38-year-old female patient with a history of tetralogy of Fallot repair at 10 years of age underwent pulmonary valve replacement with a mechanical prosthesis, tricuspid annuloplasty, and right ventricular outflow tract cryoablation due to pulmonary regurgitation, tricuspid regurgitation, and multiple premature ventricular contractions with sustained ventricular tachycardia. After surgery, she had an uneventful postoperative course with arrhythmia monitoring. She was discharged without incident, and a follow-up Holter examination showed a decrease in the number of ventricular ectopic beats from 702 to 41.ope

Membranous PTFE Monocusp Valveon the Right Ventricular Outflo Tract

Background: We studied the effect of membranous ePTFE(expanded polytetrafluoroethylene, Goretex) monocusp valve, known to lessen pseudointimal formation, on the right ventricular outflow tract(RVOT). Material and method: From May, 1996 to February, 1997, we operated 47 patients who received surgery on RVOT in whom we could measure the right ventricular pressure until the post-operative day 1. There were two groups: the comparative group with 19 patients using membranous Goretex monocusp valves and the ontrol group with 28 patients not using Goretex for the reconstruction of RVOT. Two groups did not show statistically significant differences in age, body weight, and McGoon ratio(p>0.05). The previous surgery was performed 19 times in the control group and 22 times in the comparative group. The RVOT reconstructions were performed by the methods of reparation a l`etage ventriculaire(REV) in 2 cases, RV to PA connection in 8 cases, redo-RVOT patch enlargement in 2, and RVOT patch enlargement in 16 cases of the control group. The comparative group had REV operation in 5 cases, Rastelli procedure in 6, redo-RVOT patch enlargement in 5, RVOT patch enlargement in 3 cases. Result: The comparative group showed significant difference shorter duration of indweling chest tube compared to the control group(p<0.04). No eminent significances were found on the aortic cross clamp time and the total bypass time. On the postoperative 7th day, right/left ventricular pressure ratio and RVOT pressure gradient were not different. During the follow-up, pulmonary insufficiency was significantly different between the two groups(p<0.04). One patient in the comparative group was died due to sepsis. Conclusion: We found that the effects of membranous Goretex monocusp valve on the RVOT was good in early results with a reduced pulmonary insufficiency. Continuous long-term follow-up study should be performed on the matter of the membranow valve function and late stenosis. Keywords: 1. Ventricular outflow obstruction 2. Pulmonary valve 3. Polytetrafluoroethyleneope

Treatment of Protein-losing Enteropathy After Fontan Procedure by Conversion to the Total Cavopulmonary Connection with Fenestration

As the operative mortality has diminished and the number of survivors has increased after Fontan procedure, morbidities related to the unnatural physiology of cavopulmonary flow have developed. One of the complications by the hemodynamic derangement after Fontan procedure is a protein-losing enteropathy. This is a rare but life-threatening complication after the Fontan operation. Treatment strategies are highly variable. But, reports on successful management are limited. We experienced three cases of protein-losing enteropathy after the Fontan operation. We report that the conversion to the total extracardiac or intracardiac cavopulmonary connection with fenestration is a satisfactory treatment modality for protein- losing enteropathy after the Fontan operation.ope

Recent Surgical Outcomes of Congenital Heart Disease according to Korea Heart Foundation Data

Background and objectives: This study presents an update of the surgical outcomes of congenital heart disease (CHD) according to Korea Heart Foundation (KHF) data. Methods: We investigated the data of the 7,305 patients who were economically supported by KHF in 2000-2014. Of them, we analyzed surgical outcomes of the 6,599 patients who underwent CHD surgery. Results: The median patient age was 1.9 years (range, 0-71.5 years). Of the 6,599 patients, 5,616 (85.1%) underwent biventricular repair and 983 (14.9%) underwent palliative procedures. The mean Basic Aristotle Score was 6.6±2.2. A complex procedure (defined as Basic Aristotle Score above 6) was performed in 3,368 patients (51.0%). The early mortality rate was 3.8%, while the late mortality rate was 1.8%. Previous reports of the KHF (1984-1999) showed that the early surgical and late mortality rates were 8.6%, and 5.3%, respectively. There were 491 neonates (7.4%); among them, the early mortality rate was 12.2% and late mortality rate was 3.7%. There were 2,617 infants (40.0%); among them, the early mortality rate was 6.0% and the late mortality rate was 2.3%. A total of 591 patients from 30 countries were helped by the KHF. Conclusions: More neonatal surgeries (491 vs. 74 patients) were performed than those in the past (1984-1999). The surgical outcomes were much better than before. Our surgical outcomes revealed that the Republic of Korea has been transformed from a country receiving help to a country that helps other low socioeconomic status countries.ope

Fate of Regurgitation of Left Atrioventricular Valve Following Repair of Atrioventricular Septal Defect

The purpose of this study was to evaluate the fate of left atrioventricular valve regurgitation(LAVVR) following repair of complete atrioventricular septal defects (AVSDs). Material and Method: Between July 1984 and March 2002, repair of complete AV defects were performed in 77 patients. Mean age at surgery was 30.23±69.11 months (range 1 to 456). Echocardiograms of all survivors after isolated AVSDs correction were reviewed. LAVVR were evaluated with color doppler echocardiography in 64 survival periodically. On each study, LAVVR severity was graded on a 1 to 4 scale, based upon the size of the regurgitated jet. Result: Mild deterioration of LAVV function was fairly common. LAVVR severity increased by >1 grade in 19 patients (30.2%) during the course of the study. However, the deterioration in LAVVR function occurred primarily between 12 and 24 months postoperatively. After the initial 24 postoperative months, LAVVR worsened on only 8 occasions and in each instance worsened by only 1 grade. Deterioration more than 3+ LAVVR occurred in only 3 patients. And deterioration to 4+ LAVVR was not observed after the initial 24 postoperative months but one. Survival curve analysis predicted a 88.2% of ten-year freedom rate from development of 4+ LAVVR after initial operation of complete AVSDs. Conclusion: Postoperative LAVVR remains fairly stable following AVSDs repair, Serious deterioration is rare after 24 postoperative months, especially after the initial 48 postoperative months. But serial follow-up study with echocariogram was need till 24 postoperative months after repair of complete AVSDs.ope

Pediatric Ventricular Assist Device

There have been great advances in ventricular assist device (VAD) treatment for pediatric patients with advanced heart failure. VAD support provides more time for the patient in the heart transplant waiting list. Augmented cardiac output improves heart failure symptoms, end-organ function, and general condition, and consequently provides beneficial effects on post-transplant outcomes. Miniaturized continuous flow devices are more widely adopted for pediatric patient with promising results. For infants and small children, still paracorporeal pulsatile device is the only option for long-term support. Younger age, congenital heart disease, biventricular support, patient's status and end-organ dysfunction at the time of implantation are risks for poor outcomes. Patient selection, timing of implantation, and selection of device for each patient are critical for optimal clinical outcomes.ope

Characteristics of Pulmonary Atresia and Ventricular Septal Defect According to Morphologic Classification and Changes of Pulmonary Artery after Modified B-T Shunt.

Purpose : The purpose of this study is to help determine the optimal time and method for operation of pulmonary atresia(PA) with ventricular septal defect(VSD). Methods : Seventy patients who were diagnosed as PA with VSD in the Pediatric Department of Cardiology, Severance Hospital between May, 1991 and April, 1995, were included in our study. Subjects were divided into two groups depending on the presence of major aorto-pulmonary collateral arteries(MAPCAs). In patients with MAPCAs, the distribution of MAPCAs concerning its relationship with central PA were analyzed, while in patients without them, morphologic changes of PA after performing conventional modified Blalock-Taussig(B-T) shunt were studied. Results : After performing modified B-T shunts, the number of cases of PA stenosis and interruption increased from 26 to 37. Fifteen cases of advanced stenosis and six cases of interrupted PA were also observed. After performing modified B-T shunt, CSAI of both PA was increased from 197?01 to 311?38, more remarkably in cases without progression of PA stenosis. Among the patients with MAPCAs, 12 cases showed PDA, while 16 cases showed confluent PA. On average, MAPCAs were present in 2.5 cases. Concerning the types of MAPCAs, 14 cases were unifocal, while 36 cases were multifocal and most of them originated from descending aorta. Conclusion : In cases where pulmonary flow is maintained by PDA, stenosis of central PA is common, and can result in retarded pulmonary arterial development or increased stricture after modified B-T shunt, so careful attention is needed during follow-up. In cases with dominant MAPCAs, confluent PA is common, and multifocal pulmonary supply renders surgery difficult, so careful analysis of pulmonary supplies to each pulmonary segments, their shapes and relationships, are indicated preoperatively.ope

Surgical and Long Term Results for Double Outlet Right Ventricle by the Type of Ventricular Septal Defect

Background: The results of biventricular repair for double outlet right ventricle have been improved in recent series. We studied the surgical and long term results for total correction of double outlet right ventricle by the type of ventricular septal defect. Material and Method: Between November 1979 and December 2003, 126 patients had biventricular repair for double outlet right ventricle. The mean age was 1.8 years (range 1∼44) and 86 patients (68.3%) were male. We classified and studied this disease by the type of VSD. Result: The locations of VSD were subaortic in 79 (62.7%), subpulmonary in 17 (13.5%), doubly committed in 16 (12.7%) and noncommitted in 14 (11.1%). 28 patients had palliative operation before total correction and the mean interval to total correction was 41.0±45.1 months. The methods of total correction were intraventricular baffling in 37 (29.4%), intraventricular baffling with patch enlargement of right ventricular outflow tract in 49 (38.9%), intraventricular baffling with Rastelli procedure in 15 (11.9%), arterial switch operation in 8 (6.3%) and REV procedure in 4 (3.2%), etc. Hospital mortality rate was 10.3% (13 patients) and 25 reoperations were performed in 24 patients (19.0%). The risk factors for hospital mortality and reoperation were cardiopulmonary bypass time (p=0.020) and previous palliative operation (p=0.013), respectively. Follow up was possible in 98 patients and mean follow up period was 118.9±70.7 months. The percent survival and survival for freedom from reoperation at 15 years were 82.5% and 66.7%, respectively. The survival rate was significantly lower (p=0.003) in transposition of great artery type and remote type than in simple ventricular septal defect type and tetralogy of Fallot type, but there was no statistical differences in survival rate for freedom from reoperation. Conclusion: It is thought to be that acceptible surgical and long term results can be obtained with application of appropriate methods of repair for double outlet right ventricle.ope