• 한국환경보건학회지
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• 제32권3호
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• pp.222-226
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• 2006

Smoking of tobacco cigarettes is associated with a rise in blood pressure together with increase in heart rate. This study was aimed to examine the acute effect of tobacco and non-tobacco cigarette smoking on the blood pressure and heart rate by randomized crossover study. In the results, systolic/diastolic blood pressure and heart rate changes after smoking were significantly different between male and female group. Blood pressure and heart rate were elevated after smoking, but statistical significance for the difference was identified only in the female group. Because Non-tobacco smoke made from leaves of E. ulmoides has no nicotine, its effect on blood pressure and heart rate was negligible. Remarkable difference of heart rate changes in women was observed between tobacco cigarette smoking group and non-tobacco cigarette smoking group.

• 대한핵의학회:학술대회논문집
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• 대한핵의학회 2000년도 2nd Korea-China Congress of Nuclear Medicine and 39th Annual Spring Meeting if the Korea SOciety Nuclear Medicine
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• pp.79.1-79.1
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• 2000

• Journal of Chest Surgery
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• 제27권10호
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• pp.824-832
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• 1994

Recently we developed the concept of totally implantable electrohydraulic artificial heart. We tested the artificial heart which was drived by external compressive air in the calves. All three calves had pneumonia before surgery, so postoperative course was not only bad but also the results was not good. The first calf died severe pneumonia on 76th day, the second calf died from troublesome bleeding and uncertain allergic like reaction, and the third died because of bleeding. However, the performance of the artificial heart was good, and especially the blood contacting surface showed excellent hemocompatibility. The anatomic fitting was also very good even in the 35 Kg small newborn calf. During treadmill test, the first calf did not well tolerate for 1 minute but by the Full Fill Full Empty control method the artificial heart responsed well to the physiologic needs. In conclusion, the artificial heart had the very good hemocompatible surface, however, the volume of the artificial heart was a little deficient for the calf and the control algorithm needed further development.

• 대한의용생체공학회:의공학회지
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• 제28권4호
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• pp.441-448
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• 2007

Heart rate variability (HRV) in electrocardiogram (ECG) is an important index for understanding the health status of heart and the autonomic nervous system. Most HRV analysis approaches are based on the proper heart rate (HR) data. Estimation of heart rate is thus a key process in the HRV study. In this paper, we report an innovative method to estimate the heart rate. This method is mainly based on the concept of periodicity transform (PT) and instantaneous period (IP) estimate. The method presented is accordingly called the "PT-IP method." It does not require ECG R-wave detection and thus possesses robust noise-immune capability. While the noise contamination, ECG time-varying morphology, and subjects' physiological variations make the R-wave detection a difficult task, this method can help us effectively estimate HR for medical research and clinical diagnosis. The results of estimating HR from empirical ECG data verify the efficacy and reliability of the proposed method.

• The Journal of the Acoustical Society of Korea
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• 제28권2E호
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• pp.72-78
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• 2009

Heart sound segmentation into its components, S1, systole, S2 and diastole is the first step of analysis and the most important part in the automatic diagnosis of heart sounds. Conventionally, the Shannon energy envelope peak detection method has been popularly used due to its superior performance in locating S1 and S2. Recently, the HMM has been shown to be quite suitable in modeling the heart sound signal and its use in segmenting the heart sound signal has been suggested with some success. In this paper, we compared the two methods for heart sound segmentation using a common database. Experimental tests carried out on the 4 different types of heart sound signals showed that the segmentation accuracy relative to the manual segmentation was 97.4% in the HMM based method which was larger than 91.5% in the peak detection method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.641-642
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• 2006

The purpose of this work is to investigate the effect of work load on heart rate variability (HRV) which is widely used marker of the autonomic nervous system activity. Average heart rate, rating of perceived exertion, and the power spectrum of heart rate variability were investigated in seven healthy males during exercise at various work loads. The subjects were divided into two groups according to the average heart rate during exercise, group 1 with lower heart rate and group 2 with higher heart rate. HF component showed decrease followed by increase with workload. Accordingly, the LF/HF ratio showed increase followed by decrease with workload. The peak in LF/HF ratio of group 1 was at the lower workload than that of group 2.

• Journal of Chest Surgery
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• 제19권4호
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• pp.663-671
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• 1986

100 cases of open heart surgery were done in the Dept. of Thoracic and Cardiovascular Surgery, Won Kwang University Hospital from July, 1984 to October, 1986. l. Among the 100 cases, there were 51 cases [51%] of acyanotic congenital heart anomalies, 10 cases [10%] of cyanotic congenital heart anomalies and 39 cases [39%] of acquired heart disease. 2. The age distribution of 100 cases was 18 months to 56 years old and mean age was 10.8 years old in congenital heart anomalies and 34.7 years old of acquired heart disease. 3. The overall mortality was 8%. and the mortality in each entity is 5.9% in congenital acyanotic cases, 10% in congenital cyanotic cases and 10.3% in acquired valvular heart disease. 4. For myocardial protection, high concentration potassium of cold blood cardioplegic solution [30mEq/L] had been used, associated with topical cooling of ice-slush.

• Journal of Chest Surgery
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• 제22권2호
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• pp.202-211
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• 1989

We experienced a series of animal experimental studies of the total artificial heart in 1988. So called, "Korean Heart* was used in this study, which is developed and fabricated in the Department of Biomedical Engineering, College of Med., S.N.U.. "Korean Heart" is a Rolling-Cylinder Motor-Driven type which is a newly developed electromechanical heart over the shortcomes of the previous artificial hearts, especially pneumatic type. The advantages of the "Korean Heart" are total implantability, quiet and smooth movement, small size fittable in oriental people, etc. The animal experiments were performed two times, as an assist device in sheep and total artificial heart implant experiment in calf weighing 100 kg. After total implantation, the artificial heart was well functioned in movement and hemodynamic control. So that, the calf was recovered excellently, which was able to stand up by herself and take an oral intake. Total survival time was 100 hours and the cause of death was a sudden pumping failure [electrical connection problem]. Several postoperative laboratory results almost within normal limits and no hemolysis, but in autopsy, the multiple thromboembolic findings were seen at the lung and kidney.n at the lung and kidney.

• Journal of Chest Surgery
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• 제22권6호
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• pp.887-893
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• 1989

Donor availability is a major limiting factor in heart transplantation. Prolonging donor heart preservation would facilitate distant heart procurement. The setup used was the isolated retrograde perfused nonworking rabbit heart model and 4 hours of preservation at 2oC. And the electron microscopic findings of the myocardium were evaluated after reperfusion for 5 minutes. The following three groups [each group, n=4] were prepared: Group I: the heart was arrested with the St. Thomas Hospital solution [STH] and stored in Ringers lactate solution [RLS]; Group II: the heart was arrested with STH and stored in Modified Collins-Sachs solution [MCS]; Group g: the heart was arrested with and stored in MCS. The result was the most severe myocardial injury in the Group III on electron microscopic study.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2410-2414
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• 2008

Human heart valves diseased by congenital heart defects, rheumatic fever, bacterial infection, cancer may cause stenosis or insufficiency in the valves. Treatment may be with medication but often involves valve repair or replacement (insertion of an artificial heart valve). Bileaflet mechanical heart valves (BMHVs) are widely implanted to replace the diseased heart valves, but still suffer from complications such as hemolysis, platelet activation, tissue overgrowth and device failure. These complications are closely related to both flow characteristics through the valves and leaflet dynamics. In this study, the physiological flow interacting with the moving leaflets in a bileaflet mechanical heart valve (BMHV) is simulated with a strongly coupled implicit fluid-structure interaction (FSI) method which is newly organized based on the Arbitrary-Lagrangian-Eulerian (ALE) approach and the dynamic mesh method (remeshing) in FLUENT. The simulated results are in good agreement with previous experimental studies. This study shows the applicability of the present FSI model to the complicated physics interacting between fluid flow and moving boundary.