• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권1호
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• pp.23-29
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• 2005

This paper presents the characteristics of leakage currents flowing through ZinC Oxide(ZnO) surge arrester blocks under mixed direct and 60 Hz alternating voltages. A mixed voltage, in which an alternating voltage is superimposed upon a direct voltage, appears on the HVDC system network. The mixed direct and alternating voltage generator with a peak open-circuit of 10 kV was designed and fabricated. The leakage currents and V-I curves for the fine and used ZnO surge arrester blocks were measured as a function of the voltage ratio k, where the voltage ratio k is defined as the ratio of the peak of alternating voltage to the peak of the mixed voltages. The resistive component in the leakage current in the low conduction region is significantly increased with increasing the voltage ratio k. The V-I characteristic curves for the mixed voltages lies between the direct and alternating characteristics, and the cross-over phenomenon in the high conduction region was appeared.

• Journal of Electrochemical Science and Technology
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• 제9권3호
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• pp.212-219
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• 2018

Perovskite type ceramic membranes which exhibit dual ion conduction (proton and oxygen ion conduction) can permeate water and can aid solving operational problems such as temperature gradient and carbon deposition associated with a working solid oxide fuel cell. From this point of view, it is crucial to reveal water transport mechanism and especially the nature of the surface sites that is necessary for water incorporation and evolution. $BaCe_{0.8}Y_{0.2}O_{3-{\alpha}}$ (BCY20) was used as a model proton and oxygen ion conducting membrane in this work. Four different catalytically modified membrane configurations were used for the investigations and water flux was measured as a function of temperature. In addition, CO was introduced to the permeate side in order to test the stability of membrane against water and $CO/CO_2$ and post operation analysis of used membranes were carried out. The results revealed that water incorporation occurs on any exposed electrolyte surface. However, the magnitude of water permeation changes depending on which membrane surface is catalytically modified. The platinum increases the water flux on the feed side whilst it decreases the flux on the permeate side. Water flux measurements suggest that platinum can block water permeation on the permeate side by reducing the access to the lattice oxygen in the surface layer.

• 대한의용생체공학회:의공학회지
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• 제38권6호
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• pp.313-320
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• 2017

Myocardial infarction is a disease caused by stenosis of the coronary arteries. The high risk of sudden cardiac death due to myocardial infarction has triggered related researches that have been actively studied so far. However, these studies focused on the clinical results, which are mainly based on observations of symptoms due to infarction through electrocardiograms. Therefore, in this study, we tried to analyze the behavior of heart according to the position and volume of infarction lesion through the computer simulation study using three dimensional ventricular models. In order to implement infarction, commercial software was used to simulate cell necrosis due to blockage of a specific coronary. In addition, the conduction block due to infarction was mimicked by reducing the electrical conduction in the infarcted area, which was 100 times less than the electrical conduction of the whole ventricular lattice implemented by the finite element analysis method. Thus, this study classified the infarcted cases into the upper, middle, lower, and apex according to lattice data of eight different infraction areas. In other words, we assumed that myocardial infarction would have inherent electro-dynamic characteristics depending on the location and extent, and analyzed the ventricular electromechanical responses for infarction lesions using a three dimensional cardiac physiome model. The results showed that the volume of infarction did not directly affect the cardiac responses, but the location of the infarction lesions could influence the ventricular pumping efficiency. These suggest that the occlusion of specific coronary arteries may have a fatal effect on the decline in ventricular performance. In conclusion, although location of myocardial infarction lesions is considered to be an important variable to be considered clinically rather than lesion size, quantitative predictions should be made more in the future considering physiological factors such as lesion location and direction of myocardial fiber at that location.

• 대한핵의학회지
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• 제28권1호
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• pp.44-51
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• 1994

연구배경 : 정상적인 자극전도계를 통한 좌심실과 우심실의 전기적 활성은 거의 동시에 일어나지만 심실내에 자극전도 장애가 있는 경우 비정상적인 수축이 있게 된다. 이러한 변화는 자극전달의 속도가 빠르고 복잡하여 정량화 할 수 없었다. 이에 심실내 전도장애가 있는 환자를 대상으로 방사성동위원소 심장풀스캔(radionuclide gated blood pool scan, GBPS)을 이용한 위상분석(phase image analysis)을 통하여 비정상적인 수축정도를 정량화하고자 하였다. 방법 : 심실내 전도장애 환자 및 조기수축증후군환자에서 방사능동위원소 심장풀스캔을 이용하여 심전도상 전도장애를 보인 환자를 대상으로 좌심실 구혈률, 위상각, 위상각의 표준편차, 전체반값폭, 위상각의 범위를 측정하였으며 비정상적으로 수축하는 과정을 위상영상분석을 통하여 심실의 비정상적으로 수축하는 과정을 비교 분석하였다. 결과 : 좌각블록환자에서는 위상각의 포준편차, 전체 반값폭, 위상각의 범위는 정상대조군에 비하여 유의한 차이를 보였으나 우각블록환자에서는 대조군과 차이가 없었다. WPW 증후군환자에서는 위상각의 표준편차와 위상각의 범위는 유의하게 증가하였고 전체반값폭은 정상대조군에 비하여 차이가 없었다. 정상심전도를 보인 환자에서는 위상각의 지연없이 좌심실과 우심실을 거의 동시에 심장수축을 유발하는 것을 관찰한 반면 좌각블록을 가진 환자에서는 RV에 비하여 늦은 LV의 phase을 보였고, 우각블록을 가진 환자에서는 LV에 비하여 늦은 RV phase을 보였다. 또한 WPW 증후군환자의 77%에서 Kent bundle의 위치를 영상분석으로 추정할 수 있었다. 결론 : 이상의 결과로 GBPS의 위상영상분석은 심전도장애 및 조기수축증후군 환자에서 위상영상을 통하여 심장의 활성화 과정을 알아볼 수 있었으며 위상영상히스토그램을 통하여 이를 정량화하여 심실내 전기적 활성의 비동시성 여부를 추적관찰 할 수 있는 비관혈적검사임을 확인하였다.

• Journal of Yeungnam Medical Science
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• 제4권2호
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• pp.23-27
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• 1987

저자들은 1986년 5월부터 1987년 4월까지 건강 진단 목적으로 검사한 대구시내 국민학생 및 중학생의 심전도를 분석하여 다음과 같은 결론을 얻었다. 대상학생은 13,801명으로 남자 7,526명, 여자 6,275명이였다. 심전선도에서 이상소견을 보인 수는 145명(1.05%)으로 남자 98명, 여자 47명이였다. 심방 및 심실비대는 우심방비대 2명, 좌심방비대 5명, 우심실비대 35명(0.25%) 및 좌심실비대 16명(0.12%)이였다. 이소심박중 심방성 조기수축 12명(0.09%), 심실성 조기수축 8명(0.06%) 및 방실접합부율동 5명(0.04%)이였다. 정도장애 부정맥중 1도방실전도장애 21명(0.15%), 1형 2도방실전도장애 1명, 방실해리 1명, 우각전도차단 36명(0.26%), 좌각전도차단 1명 및 WPW증후군 2명이였다. 비특이적 ST, T변화가 3명이였고, 동성빈맥이 1명이였다.

• 한국임상수의학회지
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• 제24권3호
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• pp.422-425
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• 2007

6개월령 수컷 진도종 개가 교통사고에 의한 골반 골절 교정술을 위하여 내원하였다. 일반적인 수술 전 검사에서 마취와 관련해 위험성 있는 이상은 발견되지 않았다. 이 개는 아트로핀으로 전처치하고, 유도마취로 thiopental을 주사하였으며 유지 마취 약물로 isoflurane을 사용하였다. 수술 시작 40분 후 갑자기 서맥이 발생하여 아트로핀(18ug/kg)을 천천히 정맥주사 하였으나 즉시 맥박이 증가하지 않고 오히려 heart rate가 감소하며 방실 전도 차단($2^{nd}$ degree type I)이 발생하였다. 따라서 ephedrin을 즉각적으로 주사하였으며, 투여 7분 후 정상 심박으로 회복되었다. 본 증례는 개에서 고용량 atropine 투여로 드물게 발생하는 역설적 방실전도 차단 임상예이다.

• Genomics & Informatics
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• 제10권2호
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• pp.110-116
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• 2012

Recent several studies have shown that the genetic variation of SCN5A is related with atrioventricular conduction block (AVB); no study has yet been published in Koreans. Therefore, to determine the AVB-associated genetic variation in Korean patients, we investigated the genetic variation of SCN5A in Korean patients with AVB and compared with normal control subjects. We enrolled 113 patients with AVB and 80 normal controls with no cardiac symptoms. DNA was isolated from the peripheral blood, and all exons (exon 2-exon 28) except the untranslated region and exon-intron boundaries of the SCN5A gene were amplified by multiplex PCR and directly sequenced using an ABI PRISM 3100 Genetic Analyzer. When a variation was discovered in genomic DNA from AVB patients, we confirmed whether the same variation existed in the control genomic DNA. In the present study, a total of 7 genetic variations were detected in 113 AVB patients. Of the 7 variations, 5 (G87A-A29A, intervening sequence 9-3C>A, A1673G-H558R, G3578A-R1193Q, and T5457C-D1819D) have been reported in previous studies, and 2 (C48G-F16L and G3048A-T1016T) were novel variations that have not been reported. The 2 newly discovered variations were not found in the 80 normal controls. In addition, G298S, G514C, P1008S, G1406R, and D1595N, identified in other ethnic populations, were not detected in this study. We found 2 novel genetic variations in the SCN5A gene in Korean patients with AVB. However, further functional study might be needed.

• Journal of Chest Surgery
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• 제23권1호
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• pp.16-21
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• 1990

From November 1978 through June 1989, 33 patients aged 3 months to 27 years [mean 9.7 years] underwent repair of intracardiac defects associated with corrected transposition. Five patients had had previous palliative surgery. Operation were performed in 31 for ventricular septal defect, 22 for pulmonary outflow tract obstruction, 16 for atrial septal defect, and 5 for anatomical tricuspid valve regurgitation. Pulmonary outflow tract obstruction was relieved by pulmonary valvotomy in 9, Rastelli procedure in 5, modified Fontan procedure in 3, and by REV procedure in 5 patients recently. Early mortality was 21.2%[7/33] and no late mortality during follow up period. Two had residual pulmonary outflow tract obstruction and one residual VSD. In eight patients, transient arrhythmia was found but soon returned to sinus rhythm. Five patients developed complete heart block and 2 were given permanent pacemaker insertion. There were 8 RBBB, 1 LBBB and one second degree atrioventricular block patients, but all showed no clinical significance. This report suggests that surgical repair of intracardiac defects associated with corrected transposition can be achieved with acceptable low risk. Though the mortality is still high, we can improved the result by advancing surgical technique, knowledge of the special conduction system, and by improving postoperative care.

• Journal of Chest Surgery
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• 제9권2호
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• pp.198-206
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• 1976

A Total of Forty eight patients underwent open-heart surgery for correction of tetralogy of Fallot at the Seoul National University Hospital from January 1974 to October 1976, with an overall survival rate of 77 per cent. Operative mortality varied according to severity of the lesion, age of the patient, nature of previous surgical treatment and presence or absence of an outflow tract patch across the pulmonary valve ring. Eleven patients died in the early postoperative period and thirty seven patients were discharged from the hospital alive. A patch of the right ventricular outflow tract and pulmonary annulus was required to relieve pulmonic stenosis in 24 patients. There were 10 deaths in this group (42%) as compared to 1 death in the group of 24 patients who were corrected without a patch. Operative mortality was especially higher when an inlay patch was placed across the pulmonary valve ring. This may be related to the possibly greater anatomic severity of these cases and to the longer operating time when a patch was used. The electrocardiogram showed right ventricular hypertrophy in 35 cyanotic patients. Intraventricular conduction was normal in 34 patients before operation. It was normal postoperatively in only 5 of 34 patients in this group who survived surgery. Complete right bundle branch block appeared at operation in 21 patients, and 8 patients developed incomplete right bundle branch block. Major causes of death were progressive cardiac failure (4), Complete atrioventricular dissociation (3), bleeding (2), cardiac tamponade (1), and sudden cardiac arrest (1)

• Journal of Chest Surgery
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• 제46권4호
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• pp.289-292
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• 2013

Through the use of a dual chamber (DDD) pacemaker, we achieved a cardiac resynchronization effect in a 51-year-old female patient who was transferred to our hospital from another hospital for an operation for three-vessel coronary artery disease. Her electrocardiogram showed a left bundle branch block (LBBB) and a prolonged QRS interval of 166 milliseconds. Severe left ventricle (LV) dysfunction was diagnosed via echocardiography. Coronary artery bypass grafting (CABG) was then performed. In order to accelerate left atrial activation and reduce the conduction defect, DDD pacing using right atrial and left and right ventricular pacing wires was initiated postoperatively. The cardiac output was measured immediately, and one and twelve hours after arrival in the intensive care unit. The cardiac output changed from 2.8, 2.4, and 3.6 L/min without pacing to 3.5, 3.4, and 3.5 L/min on initiation of pacing. The biventricular synchronization using DDD pacing was turned off 18 hours after surgery. She was transferred to a general ward with a cardiac output of 3.9 L/min. In patients with coronary artery disease, severe LV dysfunction, and LBBB, cardiac resynchronization therapy can be achieved through DDD pacing after CABG.