• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.165-170
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• 1997

In this paper, we consider the aortic sinus baroreceptor, which is the most representative baroreceptors sensing the variance of pressure in the cardiovascular system(CVS), and propose heart activity control model to observe the effect of delay time in heart period and stroke volume under the regulation of baroreflex in arotic sinus. The proposed heart activity baroreflex regulation model contains CVS electric circuit sub-model, baroreflex regulation sub-model and time delay sub-model. In these models, applied electric circuit sub-model is researched by B.C.Choi and the baroreflex regulation sub-model transforms the input, the arotic pressure of CVS electric circuit sub-model, to outputs, heart period and stroke volume by mathematical nonlinear feedback. We constituted the time delay sub-model to observe sensitivity of heart activity baroreflex regulation model by using the variable value to represent the control signal transmission time from the output of baroreflex regulation model to efferent nerve through central nervous system. The simulation object of this model is to observe variability of the CVS by variable value in time delay sub-model. As simulation results, we observe three patterns of CVS variability by the time delay. First, if the time delay is over 2.5 sec, arotic pressure, stroke volume and heart rate is observed nonperiodically and irregularly. Second, if the time delay is from between 0.1 sec and 0.25 sec, the regular oscillation is observed. Finally, if time delay is under 0.1 sec, then heart rate and arotic pressure-heart rate trajectory is maintained in stable state.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.593-601
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• 2020

This study was conducted to analyze the physical strain with heart rate monitor in timber harvesting operations in order to reduce occupational accidents. The timber harvesting activities are manual cutting(felling, limbing and bucking) with a chainsaw and extraction by cable yarder. The study took place on Japanese larch stand. The average height was 26m and average diameter at breast height(DBH) was 3 7cm. The havest unit was gentle slope to steep slope. Results showed that the heart rate increases for chocking, felling, limbing and bucking were 94.0%, 87.9%, 84.8% and 56.4% respectively. The rate of Work Load Index was higher in the limbing(61.4%) activity than other activities chocking(55.2%), felling(54.1%) and bucking(32.1%). During 50% working heart rate test it was found that limbing(1.09), chocking(1.05) and felling(1.04) was exposed to high work intensity compared to bucking(0.83). The results showed that maximum acceptable work times(felling, chocking and limbing) were 2.30 hour, 1.85 hour and 1.60 hour respectively. To avoid occupational accidents, timber harvest workers may use a suitable working hour schedule to felling, chocking, limbing.

• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.24.1-24.15
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• 2023

Background: The construction workers are vulnerable to fatigue due to high physical workload. This study aimed to investigate the relationship between overwork and heart rate in construction workers and propose a scheme to prevent overwork in advance. Methods: We measured the heart rates of construction workers at a construction site of a residential and commercial complex in Seoul from August to October 2021 and develop an index that monitors overwork in real-time. A total of 66 Korean workers participated in the study, wearing real-time heart rate monitoring equipment. The relative heart rate (RHR) was calculated using the minimum and maximum heart rates, and the maximum acceptable working time (MAWT) was estimated using RHR to calculate the workload. The overwork index (OI) was defined as the cumulative workload evaluated with the MAWT. An appropriate scenario line (PSL) was set as an index that can be compared to the OI to evaluate the degree of overwork in real-time. The excess overwork index (EOI) was evaluated in real-time during work performance using the difference between the OI and the PSL. The EOI value was used to perform receiver operating characteristic (ROC) curve analysis to find the optimal cut-off value for classification of overwork state. Results: Of the 60 participants analyzed, 28 (46.7%) were classified as the overwork group based on their RHR. ROC curve analysis showed that the EOI was a good predictor of overwork, with an area under the curve of 0.824. The optimal cut-off values ranged from 21.8% to 24.0% depending on the method used to determine the cut-off point. Conclusion: The EOI showed promising results as a predictive tool to assess overwork in real-time using heart rate monitoring and calculation through MAWT. Further research is needed to assess physical workload accurately and determine cut-off values across industries.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.865-871
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• 2012

In this study, ambulatory electrocardiogram(ECG) signal and the rhythms of heart beats are visualized in terms of R-R intervals and Heart Rate Variability(HRV) in the environment of an android plaform. With this aim, Graphical User Interface(GUI) is implemented by executing multi-thread Java programming modules including ECG, heart-beats, tachogram and visualization unit. ECG signals are acquired in an android device by receiving the data from ambulatory ECG sensory system. Finite Impulse Response(FIR) filters are implemented to eliminate the baseline wandering noises contained in the ambulatory signals and DC-offset level in R-R interval data. With simulating the normal or stress emotional state of a subject, we can find the fact that HRV can be successfully estimated and visualized in an android smart phone platform.

• Archives of Pharmacal Research
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• v.6 no.1
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• pp.69-73
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• 1983

It was reported from our laboratory that the rate of deterioration of the force of contraction was slower in heart from Panax ginseng extract treated rats. Present investigation was designed to elucidate the mechanism of the slow deterioration of contractility of ginseng treated hearts. Therefore, $^{45}Ca^{2+}$ Uptake by sarcoplasmic reticulum (SR) isolated from ginseng treated rate and control rats was studied. Rate weighing 150-250g were administered orally with ginseng ethanol extract (100mg/kg) for 10 days. Cardiac SR was isolated by differential centrifugation and $^{45}Ca^{2+}$ uptake was assessed by the Millipore method. Freshly isolated SR from treated as well as control animals did not show any differences, but after incubation for 30 and 60 min at 37.deg.C, $^{45}Ca^{2+}$ uptake of control animal SR was found to be greatly depressed. The SR of treated animal possessed a greater degree of resistance to incubation. Thus it can be concluded that ginseng may have an ability to sustain the normal function of the heart by sustaining Ca accumulation by SR involved with the excitationcontraction coupling processes.

• Journal of Chest Surgery
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• v.13 no.4
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• pp.321-337
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• 1980

The increasing use of cardioplegic solution for the reduction of ischemic tissue injury requires that all cardiplegic solution be carefully assessed for any protective or damaging properties. This study describes functional, enzymatic and structural assessment of the efficiency of three cardioplegic solutions (Young & GIK, Bretschneider, and $K^{+}$ Albumin solution) in a Modified Isolated Rat Heart Model of cardiopulmonary bypass and ischemic arrest. Isolated rat heart were subjected to a 2-minute period of coronary infusion with a cold cardioplegic or a noncardioplegic solution immediately before and also at the midpoint of a 60-minute period of hypothermic ($10{\pm}1$. C) ischemic cardiac arrest. The results of this study were as follow: 1. Spontaneous heart beat after ischemic arrest occured 16 seconds later after Langendorff reperfusion in the Young & GIK group (n=6), and 40 second later in the Bretschneider group (n=6) and 6 minute later in the $K^{+}$ Albumin group (n=6), and 16 minute later in the control group (non-cardioplegia). A good recovery state of spontaneous heart beat was shown in the Young & GIK and Bretschneider groups. 2. The percentage of recorveries of heart function at 30 minute after postischemic working heart perfusion were : heart rate $91.6{\pm}3.1$% (P<0.01)m oeaj airtuc oressyre $83{\pm}3$% (P<0.01), coronary flow $70{\pm}8$% (P<0.05) and aortic flow flow rate $39{\pm}9.3$% (P<0.05) in the Young & GIK group. This percentage of recoveries of the Young & GIK group was significantly greater than the control group. In the Bretschneider group, the percentage of recoveries were : heart rate $87.8{\pm}7.5$%(P<0.05), peak aortic pressure $71{\pm}2.3$% (P<0.05) and aortic flow rate $33.2{\pm}6.6$%(P<0.05). hte percentage of recoveries were significantly greater than in the control group. In the $K^{+}$ Albumin group, recoveries of heart function were poor. 3. Total CPK leakage was $131.2{\pm}12.75$IU/30 min/gm. dry weight in the control group, $50.65{\pm}12.75$IU in the Young & GIK gruop, $69.40{\pm}32.21$Iu in Bretschneider group, and $103.65{\pm}15.47$IU in the $K^{+}$ Albumin group during the 30 minute postischemic Langendorff reperfusion. Total CPK leakage was significantly less (P<0.001) in the Young & GIK group, than in the control group. 4. Direct correlatin between percentage recovery of aortic flow rate and total amount of CPK leakage from Myocardium was noticed.(Correlation Coefficient r = 0.76, P<0.001). 5. Mild perivascular edema was the only finding of light microscopic study of myocardium after 60 minute ischemic arrest with cold cardioplegic solutions and hypothermla.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.42-44
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• 2005

Many cellular phone volunteer studies have been conducted since such a social issue is raised that the long time usage of cellular phone may increase health risk. While there were various volunteer studies using GSM cellular phone on heart rate and blood pressure at abroad, very few studies using CDMA phone were conducted in domestic and abroad. In this study, the volunteer groups of 21 adults were exposed at 300 mW for half an hour, and the physiological parameters such as blood pressure, heart rate, respiration rate, and skin impedance were measured. All the parameters' results did not reveal any differences between exposure and non-exposure conditions in adults.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.11
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• pp.51-54
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• 1992

In this paper, we quantitatively evaluated the anxiety data from humans in an anxiety state. It has been reported that the electric signals of human can be correlated with their emotional state. We chose heart rate, respiration rate, temperature and skin conductance as the anxiety parameters. For experiment protocol, the subject was given exercising load to induce the anxiety state and the exercise was done using the FITRON Cycle Ergometer. We divided the data into three stages: rest period, exercise period, and recovery period. During evaluation, We counted the heart rate, slope of heart rate, temperature change, and the skin conductance.

• Journal of Sensor Science and Technology
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• v.26 no.5
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• pp.301-305
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• 2017

This paper presents a wearable human health-monitoring band. The band consists of a body temperature detector (BTD) and a hear rate detector (HRD). The BTD and HRD are realized using an inkjet-printed flexible temperature sensor and a commercial heart rate sensor module, respectively. The sensitivity of the fabricated BTD was found to be $-31/^{\circ}C$ with a linearity of 99.82%. The HRD using the commercial heart rate sensor module has a good performance with a standard deviation of 0.85 between the data of a commercial smart watch and the fabricated HRD.

• Journal of the Ergonomics Society of Korea
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• v.3 no.1
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• pp.19-24
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• 1984

As in dynamic muscular activity, to support one's body may be regarded as the static workload. An examination is made of the relationship between heart rate and oxygen uptake of three male graduate students in static working postures (sitting, squatting and standing). Though it has been believed that there exists a linear relationship between heart rate and oxygen uptake, this thesis shows that both have no relationship in the case of static postures, and that they may depend upon the characteristics of postures rather than the static workload. These results are discussed analytically. The additivity between static body postures and holding up one's hands at his maximum height is tested. Compared with the sum of energy expenditure in balancing one's body and holding up hands, the net rate of energy expenditure in performing them simultaneously is equivalent. In the case of static postures, the importance of the awareness of the characteristics and relevance of the measures is discussed.