• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1665-1668
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• 2008

Arrhythmia causes sudden cardiac death. In the past, there were medical limitations in finding the cause of arrhythmia. As an alternative solution for research of arrhythmia, there have been studies to find the causes of arrhythmia by producing a virtual heart model. Medically, arrhythmia has two main causes: abnormal occurrence of action potential and abnormal conduction of action potential. Based on these, the tachycardia, which is one of the arrhythmia, was manifested and the phenomenon of ventricular fibrillation was numerically analyzed in this study. For this purpose, an electrophysiological model of ventricular cells was implemented, which was subsequently applied to the reaction-diffusion partial differential equation to interpret the macroscopic conduction phenomenon in two-dimensional tissues. The ventricular fibrillation refers to a condition where several irregular waves occur in cardiac tissue, whose generation mechanism is pathologically related to the cardiac tissue.

• 대한산업공학회지
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• 제42권4호
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• pp.290-295
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• 2016

This paper proposes a new method for the automatic detection of atrial fibrillation (AF), using Markov regime switching GARCH (1, 1) model. The proposed method is based on the observation that variability patterns of heart rate intervals during AF significantly differ from regular patterns. The proposed method captures the different patterns of heart rate intervals between two regimes : normal and AF states. We test the proposed method using Massachusetts Institute of Technology-Beth Israel Hospital (MIT-BIH) atrial fibrillation database, and demonstrate the effectiveness of the proposed method.

• 한국염색가공학회지
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• 제18권4호
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• pp.20-27
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• 2006

Lyocell is a not only environmentally-friendly but also very advantageous fiber. When Lyocell is soaked in water, its wet tenacity does not decrease and elongation and moisture regain of it are better than cotton. However, one drawback of lyocell is its fibrillation. The fibrills of lyocell were generated during wet process such as scouring and dyeing deteriorates the dyeing color depth and the appearance of fabric. The purpose of this study was to decrease the fibrillation tendency of lyocell fabric using crosslinking agent, epichlorohydrine(ECH). The effects of NaOH scouring and ECH crosslinking were observed. The different types of ECH addition methods to lyocell and the various concentrations of ECH in crosslinking reaction onto dyeing characteristic and fibriallation were investigated. Weight loss and whiteness index of crosslinked lyocell by ECH were examined. K/S values of ECH treated lyocell fabrics dyed with reactive dye were measured and SEM images of untreated and treated lyocells were observed extensively to define the fibrillation tendency. The results were as follows ; 1) ECH treatment showed the effect of weight loss and scouring because ECH crosslinking reaction was conducted in alkaline condition. 2) The increase in ECH concentration from 5 to 30% does not affected K/S value changes. 3) ECH crosslinking can effectively prevent the fibrillation tendency of lyocell.

• Journal of Chest Surgery
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• 제26권4호
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• pp.249-254
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• 1993

Atrial fibrillation is commonly associated with organic mitral valve disease including rheumatic valvular heart diasease or mitral valve prolapse and so forth. Although spontaneous sinus reversion may occur in some patients after mitral valve operation, recurrence of atrial fibrillation is the rule in most of these patients. We have tried to maintain sinus rhythm after mital valve operation with oral quinidine therapy, and we will show the efficacy of this therapy in this report. From January 1986 to August 1992, 60 patients of mitral valvular heart disease, who had had atrial fibrillation preoperatively and gained sinus rhythm postoperatively, were selected for this study. These patients were divided into 2 groups: Control group [n=30] and Quinidine trial group [n=30]. The age,sex, duration of symptoms,left atrial size and other risk factors of the reversion to atrial fibrillation were adjusted to be similar between the two groups. The maintenance rate of sinus rhythm was calculated by Kaplan-Meier method, and the rate was significantly higher in quinidine trial group than in control group [ p=0.0001 ]. Univariate analysis was performed on the risk factors of reversion to atrial fibrillation, and the difference of maintenance rate between the two groups were corrected with this result: the difference was still statistically significant [ p=0.0205 ]. The quinidine levels were measured in postoperative days, and there were no difference of serum quinidine level between the quinidine success group and quinidine failure group. In conslusion, oral quinidine therapy was effective for the maintenance of sinus rhythm after mitral valve operation compared to control group, and there was no correlation between the serum quinidine level and clinical efficacy of quinidine therpy.

• Journal of Chest Surgery
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• 제44권1호
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• pp.18-24
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• 2011

Background: We evaluated the efficacy of Cox-maze IV procedure using bipolar irrigated radiofrequency ablation and cryothermy in chronic atrial fibrillation associated with valvular heart disease. Material and Methods: From November 2005 to June 2009, ninety four patients have undergone valvular heart surgery with Cox-maze IV procedure. Preoperative duration of atrial fibrillation was $7.6{\pm}6.5$ years and follow-up duration was $22.7{\pm}12.3$ months. Results: There were two (2.1%) postoperative deaths not related to maze procedure. Two cerebrovascular accidents, five low cardiac output syndromes and two permanent pacemaker implantations have occurred after surgery. Preoperative ejection fraction on echocardiography was $55.3{\pm}8.1%$ and ejection fraction of postoperative six month was $54.7{\pm}6.5%$. Left atrial size of preoperative and postoperative were $61.5{\pm}11.6\;mm$ and $53.1{\pm}8.4\;mm$ at each. Freedom from atrial fibrillation rate at postoperative six-month was 80.7% and the cases of recurrence of atrial fibrillation after six months were three (3.3%). Risk factors for failure or recurrence of maze procedure were old age (p=.010) and preoperative moderate or severe tricuspid regurgitation (p=.033). Conclusion: The Cox-maze IV procedure using RFBP2 and cryothermy is quite safe and freedom from atrial fibrillation at postoperative 6 month was 82.5%. Risk factors for failure or recurrence of atrial fibrillation after Cox-maze IV were old age and preoperative over moderate tricuspid regurgitation.

• 대한의용생체공학회:의공학회지
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• 제25권2호
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• pp.119-127
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• 2004

본 연구에서는 심장 돌연사(sudden cardiac death, SCD)의 주된 원인인 심실세동(ventricular fibrillation)을 기존의 monophasic 제세동기와는 달리 낮은 에너지에서 효율적으로 제거할 수 있는 biphasic 자동형 제세동기를 개발하였다. 개발한 제세동기는 고전압 충 $.$ 방전부와 신호 처리부의 하드웨어와 세동검출 알고리즘과 시스템 제어 알고리즘의 소프트웨어로 구성하였고, 160번의 연속적인 충 $.$ 방전 테스트를 통하여 안정성을 확인하였으며, ECC simulator에서 발생되는 6종의 총 30가지 세동신호에 실시간 세동점출 알고리즘을 적용하여 검출능력을 평가하였다 또한 그 시스템의 임상적 효용성과 안전성을 검증하기 위하여 5마리의 돼지를 대상으로 시스템의 적절한 세동 검출 및 세동 제거 능력을 실험하였고 그 후 시스템의 효용성을 향상시키기 위한 연구로 동일한 에너지를 다른 전압 레벨에서 방전시켜 이에 따른 제세동 효율을 조사하였다.

• Journal of Chest Surgery
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• 제30권3호
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• pp.287-292
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• 1997

심방세동은 가장 흔한 부정맥 질환으로서,특히 승모판막 질환이 있는 경우에는 60%에 이르는높은 빈도의 유병율을 보이는데,심방세동 환자의 약 113에서 혈전 색전증을 일으키고,혈전 색전증이 생긴 환자의 약 60%에서는 사망에 이르거나 심각한 합병증이 초래되므로 심장질환에 대한 수술시,동반 심 방세동에 대한 적극적 인 치료가 고려되어야 한다. 서울대학교병원 흉부외과학교실에서는 1994년 4월부터 1995년 6월까지 심방세동을 동반한 심장질환 을 가진 20명의 환자에서 Maze 술식을 포함한 개심술을 시행하였다 대상환자들의 남녀 성비는 남 '녀 : 6 : 14 이 었으며, 평균연령은 48$\pm$11세 (31 ~66세) 였다. 1년이상 지 속된 만성 심방세동이 14례(70%)였고, 1년미만인 경우가 6례(30%)였으며,심방세동의 과거력은 평균 36$\pm$42개월(1~132개월)이었다. 수술전 혈전전색증의 과거력이 있었던 경우가 7례(35%), 좌심방내에 혈전이 있었던 경우가 9례(45%)였다. 동반 심장질환으로는 판막질환이 19례,심실중격결손증이 1례였 으며, Maze술식과 더불어 승모판막 및 대동맥판막 치환술이 5례, 승모판막 치환술을 시행한 경우가 4 fl, 승모판막 치환술 및 삼첨판\ulcorner 성형술 4례, 승모판막 성형술 3례, 승모판막 성형술 및 삼첨판막 성형 술이 1례, 승모판막 치환술 및 관상동맥 우회술이 1례, 대동맥판막 치환술 1례, 심실중격결손봉합술이 1례 였다. 대동맥차단시간은 평균 175 :41분(116~270분)이었다. 수술과 관련된 사망은 없었으며, 수술 후 심방세동의 재발이 16명(80%)에서 있었으나, 수술후 평균 41일째 규칙적인 심박동 소견을 보였다. 수술후 합병증으로서는 저심박출증을 보였던 경우가 3례 (15%), 술전 존재하였던 반신불수의 악화가 1 례, 그리고 급성 신부전이 1례씩 관찰되었다. 20명의 외래추적 관찰기간은 평균 16.5개월(10.5~24개월) 이었는데, 외래 추적기간 중 모든 환자에서 규칙적인 심박동의 소견을 보였으며, 정상 동방결절리듬을 보인 경우 17례 (85%)중에서 항부정맥제의 투여가 필요 없는 경우가 13례 (76%)이고 나머지 4례에서는 항부정맥제를 투여중이며, 접합부 율동을 보이는 3례 (15%) 중 2례에서는 항부정맥제를 투.i중이고, 1 례는 접합부 서맥으로 인공심박동기 (DDD-R type : AAI mode)의 삽입이 필요했다. 추적기간 중에 심에 코검사는 19명에서 시행하였는데, 우심방 수축력이 보이는 경우가 1 례 (95%) 이었고, 좌심방 수축력은 12례 (63%)에서 명백히 관찰되 었다. 심장질환에 대한 개심술시 Maze술식을 동반시행할 경우심장허혈시간이 길어지는 단점이 있으나, 최근의 발달된 심근보호법의 적용으로 수술에 따른 위험을 최소화할 수 있으므로 심방세동의 적극적 인 치료를 고려하여야 할 것으로 사료된다.

• Journal of Chest Surgery
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• 제18권4호
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• pp.679-691
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• 1985

Ninety patients underwent mitral valvular heart surgery associated with or without aortic valve surgery and subjected to a clinical study in relation to their control of postoperative atrial fibrillation. There were 26 males and 64 females ranged in age from 16 to 56 years with a mean of 35.2 years. Systemic arterial embolizations were observed in 11 patients [12.2%]. Four patients of them were in normal sinus rhythm and 7 in atrial fibrillation. Out of these, left atrial thrombi were found only in 2 at the operation. Intraoperatively confirmed left atrial thrombi were in 16 patients [17.7%] of all 90 patients: Eleven patients occurred at the age of more than 40 years, 14 were in atrial fibrillation and 2 only had previous episodes of systemic arterial embolization. Sixty three patients underwent isolated mitral valve surgery [OMC 28, MVR 35] and 27 patients associated with aortic valve surgery along with mitral valve [OMC+AVR 13, MVR+AVR 14]. Preoperatively, 44 patients [48.9%] were in normal sinus rhythm. Of them, 35 patients [79.5%] revealed normal sinus rhythm thoroughly after operation without any aid of digitalis or quinidine and 5 patients [11.4%] restored normal sinus rhythm with digitalization alone. Other 3 patients converted to normal sinus rhythm with the addition of quinidine, however, in 1 patient who was resistant to quinidine therapy, electrocardioversion was carried out on the postoperative third week showing normal sinus rhythm. Thus, the most atrial fibrillations that occurred for the first time in the postoperative period, were able to reverted to normal sinus rhythm responding well to antiarrhythmic therapy. Preoperatively, 46 patients [51.1%] were in atrial fibrillation. Of them, only 5 patients returned to sinus rhythm after operation without any aid of digitalis or quinidine and other 5 restored normal sinus rhythm with digitalization: namely 2 restored within early postoperative period and 3 after more than 3 months. Eight patients well responded to quinidine therapy showing normal Sinus rhythm. So far, 25 patients have remained in persistent atrial fibrillation on 6 to 36 months follow-up. In view of these, 17 patients [68%] were over 40 years of age, 22[80%] had long duration of symptom over 5 years and 10[40%] have had atrial thrombi before operation. Left atrial dimension were still more than 40mm in 21 patients on follow up M-mode echocardiogram. One month after operation, 87 hospital survivors were improved by at least one functional NYHA class. There were 3 operative deaths [3.3%, bleeding 1, LCOS 2] and 4 late deaths [LCOS 1, valve thrombosis 1, late bleeding 1, fulminant hepatitis 1] during follow-up period. According to our limited experience, we may conclude that better results will be expected with the addition of quinidine therapy judiciously in the cases of postoperative persistent atrial fibrillation who were aged or had longer history of symptom and left atrial thrombi.

• Journal of Chest Surgery
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• 제37권7호
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• pp.609-612
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• 2004

Cox-Maze III 술식이 심방세동의 전형적인 수술요법이지만 탁월한 수술성적임에도 불구하고 수술의 복잡성, 장시간의 체외순환, 술 후 출혈의 위험부담으로 보편적이지는 못하다. 최근 들어서 심방세동의 병리기전에 대한 이해와 절개 및 봉합의 대안으로 여러 가지 에너지원의 개발로 인하여 Cox-Maze의 변형술식이 급격하게 발전되고 있다. 본원에서는 심폐기를 사용하지 않고 극초단파(microwave)를 이용하여 심방세동을 교정한 후 33개월 현재 양호한 상태로 동율동을 보이고 있어 문헌 보고하는 바이다.

• 한국의류학회지
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• 제25권1호
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• pp.144-153
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• 2001

The effect of crosslinking on hand of the cellulase treated Tencel fabrics was investigated. Tencel fabrics were crosslinked with DMDHEU, mechanically prefibrillated, hydrolyzed by cellulase, and treated with softener. The treated fabrics were characterized by add-on, weight loss, DP rating, WRA, strength, SEM analysis and hand measurement. As DMDHEU concentration increased, weight loss of DMDHEU/cellulase treated fabrics decreased. However, cellulase treatment decreased DP properties and strength retention. Less fibrils were observed in the cellulase treated fabrics after DMDHEU treatment than the cellulase treated ones. It was confirmed that crosslinking with DMDHEU treatment was effective to control fibrillation. At 5% of DMDHEU concentration, DMDHEU/cellulase treated fabrics showed softer, smoother and bulkier hand compared with other treated fabrics. Among mechanical properties, bending and shearing properties were decreased progressively through DMDHEU, cellulase, and softener treatment. DMDHEU treatment contributed to impart resilience, cellulase treatment to bulkiness and softener treatment to smoothness. As the treatment of DMDHEU, cellulase, and softener progressed NUMREI, FUKURAMI, and THV increased with the exception of KOSHI.