• Korean Security Journal
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• no.31
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• pp.7-24
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• 2012

In this study a practical guarding work is carried out for 180 minutes as the same as the actual guarding work that is done by nine students of the department of security services in K University in order to investigate changes in circadian rhythms during long hour guarding in bodyguards at practical sites. In the results of the tests of the heart rate variation and autonomic nervous system with the interval of 30 minutes using HRV (Heart rate variability), there are no significant differences in HRV and SDNN and that leads to maintain it stably during the guarding work for 180 minutes. In the case of TP which reflects the overall activity level in the autonomic nervous system, it shows a high significant difference (p<.05) at 90 and 120 minutes compared to that of normal states. Also, it shows a significant decrease in the level after a lapse of 120 minutes and that shows a decrease in the activity of the autonomic nervous system for the guarding work more than 120 minutes. Although differences in VLF, LF, and HF are not significant levels, these are influenced on the change in TP. The LH/HF ratio that represents the balance between the sympathetic nerve and the parasympathetic nerve shows a significant high level (p<.05) after a lapse of 30 minutes. Thus, it is considered that the concentration of the guarding work after a lapse of 120 minutes is decreased and there are some tensions and excitations after a lapse of 30 minutes since the beginning of the guarding work.

• Journal of Chest Surgery
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• v.34 no.8
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• pp.583-590
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• 2001

The aim of this study was to compare one-year graft patency after coronary artery bypass grafting without cardiopulmonary bypass(OPCAB) with that of conventional CABG and that of on-pump beating CABG, and to demonstrate any differences in patency of various conduits among the three groups. Material and Method: We analyzed the results of OPCAB cases(group I; n=122) compared with those of conventional CABG cases(group II; n=65) and those of on-pump beating CABG cases(group III; n=19). In group I, coronary angiography(CAG) was performed immediately postoperatively and 1 year after surgery. In group II and III, CAG was performed 1 year after surgery. Graft patency was graded as grade A(excellent), grade B(fair), or grade O(occluded). Result: The average number of distal anastomoses in groups I, II, and II were 3.1$\pm$1.1, 3.7$\pm$0.9, and 3.6$\pm$0.9, respectively. In group I, postoperative CAG was performed in 92%(112/122) of patients before discharge. The patency rate(grade A+B) was 96.4$(162/168) for arterial grafts, and 85.6%(160/187) for saphenous vein grafts(SVG). One-year follow-up CAG was performed in 74%(90/122) of patients. The patency rate was 97.8%(132/135) for arterial grafts, and 67.9%(106/156) for SVG. In group II, one-year follow-up CAG was performed in 65%(42/65) of patients. The patency rate(grade A+B) was 93.5%(43/46) for arterial grafts, and 86.8%(33/38) for SVG. Conclusion: Our results demonstrated that the patency rate of SVG after OPCAB was significantly lower than that of arterial grafts in the early postoperative CAG(p<0.001), and was also significantly lower than those of SVG of group II(p<0.001) and group III(p<0.01) in the postoperative one-year CAG, although there was no significant difference is one-year patency of arterial grafts among the three groups. Our data suggest that a specific perioperative anticoagulant therapy may be advisable in patients undergoing OPCAB with SVG.

• 순환기질환의공학회:학술대회논문집
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• 2003.11a
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• pp.46-47
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• 2003

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.691-697
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• 2013

Recently, u-healthcare device is developed and commercialized for healthcare management and emergency medical. The kinds of the measurable biomedical signals on the device are electrocardiogram, skin temperature, pulse oxygen, heart rate, respiration, etc. Specially, the photoplethysmograph(PPG) signal of these signals is the important signal in measuring oxygen, heart rate and peripheral vascular compliance. The accuracy of PPG signal reduce from influence of the motion artifacts that generated from the movements of user or patient. Therefore, this study suggests a new method to remove the motion artifact that is using optical power modulation and ICA(Independent Component Analysis). For analyzing the proposed method, we used variety of noises made by artificially. In the results of experiments, the proposed method showed good performances than an adaptive filter.

• Journal of Chest Surgery
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• v.32 no.5
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• pp.480-483
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• 1999

The widely accepted method for coronary artery bypass grafting(CABG) is performing the distal coronary artery anastomoses on the flaccid and nonbeating heart with the aid of cardiopulmonary bypass(CPB) and cardioplegic arrest. However, current cardioplegic techniques are not consistent in avoiding myocardial ischemic damages especially in high risk patients undergoing CABG. In this regard, "Off-Pump" seems to be an ideal method for preventing myocardial ischemic damage and adverse effects during CPB. However, "Off-pump" CABG is not always technically feasible. We report 2 cases of "On-pump" CABG performed on the beating heart in high risk patients; The first patient had left ventricular dysfunction(Ejection Fraction=25%), and the second patient had cardiogenic shock after percutaneous transluminal coronary angioplasty.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.209-210
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• 2009

수면단계는 수면감성을 평가하는데 있어서 중요한 생리지표로서 사용되어왔다. 그러나 수면다원검사를 이용한 전통적 수면단계 분류방법은 뇌전도, 안전도, 심전도, 근전도 등을 종합적으로 측정하므로 수면단계를 비교적 정확히 분류할 수 있지만 피험자에게 심한 구속감을 주는 문제가 있다. 본 연구에서는, 각성상태에서 교감신경계가 지배적인 반면에 수면 중에는 부교감신경계가 더 활동적인 점에 착안하여 수면단계를 간단히 분류할 수 있는 방법을 찾고자 수면단계에 따른 심박동변이도(heart rate variability: HRV)를 분석하였다. 단일채널 심전도를 이용하여 수면단계별로 HRV 의 교감신경계/부교감신경계 활성도의 비율을 분석한 결과, W(wakefulness) 단계가 NREN(non REM) 2 단계, 3 단계, 4 단계에 비하여 높게 나타났으며, NREM 4 단계는 REM(rapid eye movement) 단계와 NREM 1단계에 비하여 낮게 나타났다. 또한 교감신경계/부교감신경계 활성도 비율의 수면단계에 따라 변화하는 양상은 W, REM, NREM 1, 2, 3, 4 단계의 순으로 단조 감소하였다.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.173-176
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• 2009

심박동 변동에 반영되는 자율신경계 활동으로부터 정신적 부하 즉 스트레스 상태를 평가할 수 있다. 또한 일상생활 중에서 지속적인 심전도 모니터링인 가능하다면 심장에 부하를 줄 수 있는 운동 중에도 사전에 급작스러운 심장 이상 증세를 예상할 수 있다. 본 연구에서는 일상생활 속에서도 생체신호 측정이 가능한 무구속, 무자각, 무침습적인 심전도 측정 시스템을 개발하였다. 무선 통신을 사용하여 실시간으로 심장 활동 상태를 모니터링 할 수 있으며, 가슴에 부착이 가능한 패치 타입의 소형 전극 형태이다. 신뢰도 평가를 위하여 임상 심전도 신호와 본 전극으로 측정한 심전도 신호의 유사도를 평가하였으며 동잡음의 영향을 평가한 결과 $0{\sim}6m/h$로 걷는 경우, 심전도 파형이 안정적으로 나타나 일상생환에서의 활용가능성을 보여주었다. 동일한 피험자를 대상으로 HRV에 반영되는 스트레스의 영향을 평가하기 위하여 패치형 전극으로 심전도를 측정하여 불안, 스트레스 항목에 대한 설문지 평가, 스트레스 호르몬양을 측정하였다. 일상 상태와 스트레스 상태를 비교한 결과, 많은 파라미터에서 유의한 차이가 나타났다. 이러한 결과로부터 패치형 전극은 일상생활에서 건강 모니터링 시스템으로 활용도가 높을 것으로 기대된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.6
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• pp.1120-1129
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• 2015

In this paper, we propose an algorithm to detect movement noise in PPG(Photoplethysmography) measurements. Movement noise significantly deteriorate PPG signals in measurement, so that a movement noise detection algorithm is critical before using measured PPG signals for applications such as diagnosis. To detect movement noise, we apply wavelet transform to PPG signals instead of short-time Fourier transform and decide if the measured signlas include movement noise. To that end, we adaptively choose a wavelet, which is the most similar to the subject's PPG pattern. In the case when movement noise is intentionally added in the 20% and 30% of the total experiment time, our algorithm detects time-slots including movement and outperforms previous works.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.9
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• pp.768-776
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• 2000

본 논문에서는 심혈관 조영영상으로부터 좌심실의 형태 및 운동을 가시화하기 위해 기하학적 정보와 물리적 정보를 통합한 동적 가우시안 블럽(dynamic gaussian blob)모델을 개발하였다. 동적 가우시안 블럽 모델은 superellipsoid에 3차원 가우시안 형태함수를 갖는 단일 유한요소를 통합한 것으로, 좌심실에 작용되는 가상적인 힘에 의해 형태를 적하하고, 심박동 전 주기에서의 운동을 추적한다. 또한 벽 운동 정도에 따라 다른 색을 지정하여 볼 수 있도록 함으로써 벽 운동에 이상이 있는 부위를 육안으로 쉽게 판별할 수 있도록 하였다. 이와 같은 좌심실의 동적.색체 가시화는 형태가 변황되는 심장질환이나 허혈이나 심근경색증처럼 심실벽 운동에 이상이 있는 질환의 진단을 도울 수 있다.

• Journal of Chest Surgery
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• v.37 no.9
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• pp.793-795
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• 2004

Modified Norwood procedure with maintaining cardiac beat was done in a 30-day-old neonate. Procedure was done with regional perfusion of innominate and coronary artery. Postoperative course was uneventful. Second-stage operation (bi-directional cavopulmonary shunt) was done 4 months later. The diameter of ascending aorta was more than 5 mm, Norwood procedure can be done in beating hearts.