• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.299-304
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• 2002

본 연구에서는 자궁 내 태아의 발육지연이 주산기 사망률 및 이환율을 증가시키는 고위험 임신의 한 예로써, 태아 발육제한증과 관련한 비선형적인 자료를 통계적인 방법으로 접근하는데 초점을 두었다. 이에 정상태아와 발육제한증 태아를 판별하기 위한 분석을 실시함에 있어 신경망 이론 중 하나인 다층 퍼셉트론 모형으로 예측하고자 하였다.

• Science of Emotion and Sensibility
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• v.20 no.3
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• pp.169-180
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• 2017

Individuals with high trait anxiety try to suppress their anger expression, thus there are limits in measuring their anger using subjective behavioral evaluation. In order to overcome this limitation, this study attempted to identify the difference in the autonomic nervous system responses induced by anger in individuals with high trait anxiety. Participants were divided into two groups, anxiety and control groups. Electrocardiogram (ECG), respiration (RESP), electrodermal activity (EDA), and skin temperature (SKT) were measured while participants were presented with an anger-inducing stimulus. Heart rate (HR), standard deviation of NN interval (SDNN), root mean square of successive difference (RMSSD), low frequency (LF), high frequency (HF), LF/HF ratio, respiration rate (RR), skin conductance level (SCL), and maximum skin temperature (maxSKT) were calculated before and after presenting the stimulus. Anxiety group reported greater anger by the anger-inducing stimulus compared to the control group. Anxiety group also showed significant increase in SDNN and LF, and decrease in HF, LF/HF ratio, and RR. These results suggest that the autonomic nervous system responses may be used as objective indicators of anger experiences in individuals with high trait anxiety.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.5
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• pp.33-42
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• 2010

In this study, we have proposed a simple cardiorespiratory monitoring method based on displacements of human body which occurs due to periodic heartbeat and breathing. The proposed system consists of an aircushion, pressure sensing hardware and heartbeat and respiration signals extraction algorithm. The aircushion was used for unconstrained measurement of the respiration and heartbeats without a sensor attached on the subject's skin surface. The displacements of subject sitting on the aircushion cause small pressure variations. These variations are amplified and filtered with the pressure sensing hardware. Finally, heart rate and respiration rate are extracted by signal processing algorithm based on frequency domain filter. To evaluate the performance, extracted respiration and heart rate from proposed system were compared with conventional methods. The average sensitivity of respiration and heart rate are 98.67% and 99.24%, respectively. These results show the proposed method has advantages of installing and processing simplicity so as to be used easily in unconstrained respiration and heart rate monitoring in daily life.

• Korean Journal of Cognitive Science
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• v.16 no.3
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• pp.189-197
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• 2005

In this study, changes in performance of 2-back task, blood oxygen saturation and heart rate due to $40\%$ concentration oxygen supply were observed. Five male $(25.8\pm1.3)$ and five female $(23.0\pm1.0)$ college students were nked to perform 2-bark task during two types of oxygen (concentration $21\%,\;40\%$) administration. The experimental sequence consisted of Rest1(1 min.), 0-back Task (1 min.), 2-bark Task (2 min.), and Rest2 (4 min.) and the physiological signals such as blood oxygen saturation and heart rate were measured throughout the stages. The experimental result showed that the performance increased significantly at $40\%'s$ concentration of oxygen rather than $21\%'s$, which shows oxygen supply has positive influence on cognitive performance. When $40\%$ concentration oxygen is supplied, the oxygen saturation in the blood increased and heart rate was decreased significantly comparing to $21\%$. It is Suggested that $40\%$ oxygen can stimulate brain activation bY increasing actual blood oxygen concentration in the process of cognitive performance, and hyperoxia makes heart rate decrease.

• Journal of Chest Surgery
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• v.31 no.1
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• pp.13-19
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• 1998

Aortic aneurysm has poor prognosis and high mortality, but the incidence of aortic aneurysm is in increasing state. From July, 1986 to July, 1996, we operated on 25 patients with aortic aneurysm and analysed the clinical results and relations between the duration from symptoms onset to operation(Sx-Op), the duration from admission to operation(Adm-Op), preoperative blood pressure, preoperative heart rate and postoperative mortality, retrospectively. The patients were classified as dissecting aneurysm(10 cases), abdominal aortic aneurysm(9 cases), Marfan's syndrome(3 cases), descending thoracic aortic aneurysm(3 cases). The operative technique were graft interposition in 17 cases, Bentall's operation in 4 cases, aneurysm bypass in 2 cases, and wrapping of aorta in 2 cases. Seven patients died of several causes, bleeding in 5 cases, acute renal failure in 1 case and respiratory failure in another one case. Before 1992, the early stage of operation, 6 mortality among 14 operated patients occurred, and after then 1 mortality among 11 operated patients occurred. Eighteen survivors were followed up from 1 to 118 months(mean 50.6 months), and total follow up was 911 patient-months. During the follow up period one patient died of melena 30 months after operation. The other patients did not complain chest pain or dyspnea. The surgical mortality was improved in the late period, and the major cause of death was intraoperative or postoperative bleeding. The Sx-Op duration, the Adm-Op duration, preoperative blood pressure and preoperative heart rate were proven to have no statistical relations with postoperative mortality.

• Journal of Chest Surgery
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• v.30 no.6
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• pp.613-616
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• 1997

We present a case of 58-year-old (tamale with dilated cardiomyopathy(DCMP) in whom we performed left ventricular(LV) remodeling surgery(Batista operation) to reduce the left ventricle diameter and improve left ventricular unction. The patient was admitted September 1996 with heart failure NYHA class IV. There was severe orthopnea and peripheral edema. 2-D echocardiography(Echo) showed DCMP with the ejection fraction(EF) I5%, LV end diastolic dimension(LVEDD) 80mm, mitral regurgitation(MR) grade IV, tricuspid regurgitation ('m) grade ll. Preoperative cardiac output(CO) was 1.5/L/min and cardiac index(Cl) was 1.0 L/min/m2. We proceeded with LV remodeling surgery by resection a part of LV lateral wall between both papillary muscle, from the mitral annulus to the LV apex. Size of resected LV wall was 90 $\times$ 100 $\times$ 15 mm. At the mean time, mitral valve and tricuspid valve were repaired. Postoperative 2-D Echo showed the EF 37%, LVEDD 50 mna, trivial MR, no TR. CO was 3.SL/min and Cl was 2.3 L/min/m2. Her fuctional NYHA class was 1.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1822-1825
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• 2015

본 논문에서는 운동 전후 또는 심장 질환과 관련 있는 사용자가 체중을 측정하면서 동시에 심전도 신호를 측정하여 운동 부하에 따른 심장의 활동 상태를 모니터링 할 수 있는 장치를 고안하였다. 이를 위한 방법으로 체중계에 수정된 바이폴라 금속전극을 적용하여 표준사지 측정법을 이용하여 심장활동 신호를 측정할 수 있는 방법을 제안하였다. 체중계에서 심전도를 측정하기 위해 기존의 Ag-AgCl 전극이 아닌 금속 판 형태의 전극을 사용하였으며 이를 위해 입력 임피던스의 설계를 브릿지 형의 AC-Coupling 회로를 통해 높은 CMRR이 유지되도록 설계하였다. 또한 시시각각 변화하는 노이즈를 제거하기 위해 Savitzky-golay filter를 사용하였으며 이를 통해 Baseline wandering 이 제거된 최종 심장활동 신호를 획득하였다. R-peak 검출을 통해 기준신호와의 심박수 및 Sensitivity의 비교평가를 수행하여 이 장치의 성능을 평가한 결과 심박 검출률의 평균 Sensitivity가 97.1%로 나타났다. 동잡음 제거에 대한 알고리즘이 보다 최적화 되어 최종 출력 신호의 안정성이 향상 된다면 체중계를 통한 심박 검출의 가능성과 그 유효성이 충분할 것으로 사료된다.

• 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.

• Journal of Chest Surgery
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• v.37 no.6
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• pp.543-545
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• 2004

Postinfarction ventricular septal defect often induces cardiogenic shock and requires operative treatment early after myocardial infarction. Although the operative mortality of this disease has decreased during the past 3 decades, it is still relatively high. In this case, to prevent global myocardial ischemia, we used the technique of repair of postinfarction ventricular septal defect on a beating heart. This approach does not requir aortic cross-clamping and provides superior myocardial protection.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.4
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• pp.167-174
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• 2002

This study describes a fetal heart rate(FHR) estimation algorithm using phonogram. Using a phonogram amplifier, various fetal heart sounds are collected in a university hospital. The FHR estimation algorithms consists of a lowpass filter, decimation, envelop detection, pitch detection, and post-processing. The post-processing is the FHR decision procedure using all informations of fetal heart rates. Using the algorithm and other parameters of fetal heart sound, a fetal monitoring software was developed. This can display the original signals, the FFT spectra, FHR and its trajectory. Even though the fetal phonogram amplifier detects the fetal heart sounds well, the sound quality is not so good as the ultrasonography. In case of very week fetal heart sound, autocorrelation of it showed clear periodicity. But two main peaks in one period is an obstacle in pitch detection and peaks are not so vivid. The proposed FHR estimation algorithm showed very accurate and stable results. Since the developed software displays multiple parameters in real time and has convenient functions, it will be useful for the phonogram-style fetal monitoring device.