• Korean Journal of Clinical Laboratory Science
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• v.44 no.3
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• pp.136-141
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• 2012

The hearts of highly trained athletes show morphologic and electrocardiographic (ECG) changes that suggest the presence of cardiovascular disease, including sinus bradycardia, a striking increase in precordial R-wave or S-wave voltages, ST segment depression, and T-wave inversions. Despite a number of previous observational surveys, the determinants of abnormal ECG patterns in trained athletes remain largely unresolved. In this study, we compared the electrocardiographic characteristics of athletes to determine any sensitive indicators. Comparison between ECG patterns and cardiac physiology was performed in 21 junior athletes and 25 untrained subjects with no signs of cardiac disease. Sinus bradycardia was detected in a subset of athletes but not statistically significant between the athletes ($69.9{\pm}11.1bpm$) and the control ($72.7{\pm}9.9bpm$) group. The mean values of the PR and QTc intervals in the athletes' group were $149.2{\pm}15.4ms$ and $402.3{\pm}28.8ms$, respectively. Also, there were no significantly differences between control group and the athletes' group. In addition, the athletes demonstrated a spectrum of alterations in the 12-lead ECG pattern, including marked increase in precordial R-wave or S-wave voltages ($$SV_1+RV_5{\geq_-}35mm$$, 23.8%), QRS duration ($${\geq_-}90ms$$, 90.5%), suggestive of left ventricular hypertrophy. However, left axis deviation, ST segment depression, and T-wave changes in V5, V6 were not observed in either the athletes or control group. Our findings suggest that sinus bradycardia, precordial R-wave or S-wave voltages, and QRS duration seem to be more sensitively detected in athletes than in control group. Further researches on the electrocardiographic patterns of athletes should be carried out to improve the sensitivity and specificity of diagnostic criteria.

• 전기의세계
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• v.30 no.6
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• pp.357-365
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• 1981

When electronegative gas SF$_{6}$ is dissolved and charged with insulating oil, the effect caused in the process by electronegative characteristic is studied and also the pressure effect caused by electronegative SF$_{6}$ acting on the liquid-level is examined respectively. When inert gas Ar is used to find a pressure effect acting on the liquid-level, its effect on dielectric strength is considered in the experiment. With three kinds of impulse voltage different in the duration of wave front and wave tail, a brief experiment if carried out ot see the effects on the dielectric breakdown characteristic as the wave is changing; either if I$_{2}$ and SF$_{6}$ are added to the insulating oil, or if the oil pressure is increased by Ar the dielectric strength becomes great and the longer the duration of wave front is, the greater the increase of the breakdown voltage, because I$_{2}$ added by a small quantity brings about some hirderance in the formation of gas phase. Likewise, the greater the changed pressure is, the greater the incerase of the breakdown voltage. When SF$_{6}$ is charged, the electronegative characteristic is prevailing at the time of low balanced pressure, and the pressure effect at the time of high balanced pressure.ressure.

• Journal of the Korea Convergence Society
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• v.11 no.8
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• pp.269-278
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• 2020

The purpose of this study was to investigate the effect of left ventricular diastolic function on exercise capacity in hypertensive patients with obesity compared to the obese group. Adults who visited a general hospital in Gyeonggi-do from 2016 to 2019(man: 308, women: 192) were divided into 4 groups according to hypertension and obesity. In the hypertensive obesity group(IV), the A wave and E/E' wave were significantly higher than the normotensive obesity group(II), and the E' wave was significantly lower(respectively p<0.001). The group IV had significantly lower METS(metabolic equivalents) and exercise duration than the group II(respectively p<0.001). In group IV, E/A ratio was positively correlated with METS(p=0.025) and exercise duration(p=0.026). In contrast, E/E' wave in these groups showed a negative correlation with the exercise duration(p=0.046).

• YAKHAK HOEJI
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• v.13 no.1
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• pp.16-21
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• 1969

When ultrasonic wave with barium titanate as an ultrasonic transducer (96.84kc, 1.4kv, 240mA) was applied to a dilute glucose solution, glucose was oxidized to glucuronic acid. It was found that the lower the glucose concentration, the higher the oxidation rate. The aeration and the presence of ferrous sulfate as a catalyst were found to increase the rate. The optimal duration for applying the wave to the solution was found to be six hours.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.77-86
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• 1999

The bow flare structure of a ship is designed considering wave impact loads largely caused by relative motion of the ship and wave at rough sea. Empirical design is still used because impact phenomenon and structural behaviour due to wave impact load can not examined accurately. The objective of this study is, as the first step, to predict wave impact loads giving the structural damages to the bow flare structure from the damage data inversely, using dynamic nonlinear finite element code LS/DYNA3D, and to perform various parametric studies of wave impact pressure curve for its characteristics, such as peak height, duration time, tail height, rise time, etc.. The followings were obtained from this study: Dynamic structural responses against wave impact loads are largely affected by impact pressure impulse whose amount during duration time until peak deformation is very important.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.4
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• pp.213-220
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• 2005

An approach to calculate expected sliding distance of wave dissipating caisson breakwater is proposed. Time history of dynamic wave pressure for the calculation of sliding distance is made by extending conventional static wave pressure developed for the wave dissipating caisson breakwater. Construction of impact wave and standing wave was done by using duration time and maximum wave pressures of themselves. In the numerical analysis, the sliding distance for an attack of single wave and expected sliding distance for 50 years of wave dissipating breakwater by proposed method were compared with those by conventional method for uplift caisson breakwater. It was found that the sliding distance of wave dissipating breakwater by the proposed method is smaller than by conventional method.

• Proceedings of the KOSOMBE Conference
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• v.1990 no.05
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• pp.21-24
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• 1990

This paper presents a new algorithm for P-wave detection in the ECG signal, we get the peak, onset and offset point by using significant point extraction algorithm with 5-point derivative. To these set of extracted significant points, we apply amplitude and duration threshold criterion. we define the set of significant point meeting the criterion as P-wave candidate. Then P-wave candidate is classified through match-process with template. The template with maximum number or P-wave candidate is selected to be the P-wave.

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.907-912
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• 2009

Complex breakup behavior in the revival wave has been observed in the Belousov-Zhabotinsky(BZ) reaction system containing 1,4-cyclohexanedione (1,4-CHD) in the dish divided into two compartments with a sliding window. A same reaction mixture is poured into the two compartments individually with time difference. Wave propagation exhibited different behavior in the revival wave of the reaction system. This was largely dependent on the progress time prior to the pouring into each compartment and on the gap between the times of pouring into the two compartments. The revival wave in the reaction system is induced spontaneously as a new wave train with a long time lag after the disappearance of the initially induced wave. A thoroughgoing study of the chaotic breakup of propagating chemical wave train was to be possible since the revival wave has a longer wavelength, clearer wave-train patterns, and longer duration period.

• Clinical and Experimental Reproductive Medicine
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• v.39 no.1
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• pp.1-9
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• 2012

The safety of human exposure to an ever-increasing number and diversity of electromagnetic field (EMF) sources both at work and at home has become a public health issue. To date, many in vivo and in vitro studies have revealed that EMF exposure can alter cellular homeostasis, endocrine function, reproductive function, and fetal development in animal systems. Reproductive parameters reported to be altered by EMF exposure include male germ cell death, the estrous cycle, reproductive endocrine hormones, reproductive organ weights, sperm motility, early embryonic development, and pregnancy success. At the cellular level, an increase in free radicals and $[Ca^{2+}]i$ may mediate the effect of EMFs and lead to cell growth inhibition, protein misfolding, and DNA breaks. The effect of EMF exposure on reproductive function differs according to frequency and wave, strength (energy), and duration of exposure. In the present review, the effects of EMFs on reproductive function are summarized according to the types of EMF, wave type, strength, and duration of exposure at cellular and organism levels.

• International Journal of Advanced Culture Technology
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• v.8 no.2
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• pp.159-164
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• 2020

The response analysis of frame structure with open section beams considering warping conditions and short duration load have been performed. When a beam of frame structure is subjected under torsional moment, the cross section will deform a warping as well as twist. For some thin-walled sections warping will be large, and accompanying warping restraint will induce axial and shear stresses and reduce the twist of beam which stiffens the beam in torsion. Because of impact or blast loads, the wave propagation effects become increasingly important as load duration decreases. This paper presents that a warping restraint in finite element model effects the behavior of beam deformation, dynamic mode shape and response analysis. The computer modelling of frame is discussed in linear beam element model and linear thin shell element model, also presents a correlation between computer predicted and actual experimental results for static deflection, natural frequencies and mode shapes of frame. A method to estimate the number of normal modes that are important is discussed.