• The Korean Journal of Physiology
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• v.18 no.1
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• pp.51-65
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• 1984

In an effort to elucidate the effect of physical training on the electrocardiographic amplitudes, QRS vector, axis and QRS vector amplitude, electrocardiograms were recorded before and 1, 5 and 10 minutes after 3 minute rebounder exercise in 23 healthy male students aged between 18 and 21 years in two groups of athletes and non-athletes. ECG amplitudes were measured from lead I, $V_1$ and $V_5$ and axis and amplitudes of QRS vectors were measured from lead I and III in frontal plane, from lead $V_2$ and lead $V_6$ in horizontal plane. The results obtained are summarized as follows. ECG amplitudes: The R wave amplitude was $23.38{\pm}1.14\;mm$ in athletes which was higher than $17.91{\pm}2.00\;mm$ in non-athletes. After exercise, the difference in two groups remained significant throughout the recovery period. The S wave amplitude was increased significantly, and the T wave amplitude was decreased in both groups after exercise. The P wave amplitude was increased in both groups after exercise, and it was lower in athletes than in non-athletes. The PQ segment amplitude was zero in athletes but negative in non-athletes than in the resting state. The J point amplitude was positive in resting state and was negative after exercise in both groups. J+0.08 sec point amplitude was also lowered after exercise, and it was higher in athletes than in non-athletes. Therefore the whole ST segment was proved to be decreased after exercise. The summated amplitude of R in $V_5$ plus S in $V_1$ was $38.74{\pm}2.71\;mm$ in athletes which was higher than $32.82{\pm}2.90\;mm$ in non-athletes. After exercise, it was also significantly higher in athletes than in non-athletes. Axis of QRS vector: In frontal plane, axis of QRS vector was $62.7{\pm}7.36^{\circ}$ in athletes, it showed no significant difference between the two groups. In horizontal plane, axis of QRS vector was $-23.5{\pm}7.2^{\circ}$ in athletes which was significantly higher than $-38.8{\pm}8.2^{\circ}$ in non-athletes. After exercise, it was significantly higher than the resting state in both groups. Amplitude of QRS vector : In frontal plane, amplitude of QRS vector was $13.86{\pm}1.44\;mm$ in athletes which was significantly higher than $9.62{\pm}0.97\;mm$ in non-athletes. After exercise, it was also significantly higher in athletes than in non-athletes. In horizontal plane, amplitude of QRS vector was $19.82{\pm}2.10\;mm$ in athletes which was significantly higher than $16.90{\pm}1.39\;mm$ in non-athletes. After exercise, it was also significantly higher in athletes than in non-athletes. From the above, these results indicate that R wave amplitude in athletes was significantly higher than in non-athletes before and after exercise, and that the summated amplitude of R in $V_5$ plus S in $V_1$ in athletes was also $38.74{\pm}2.71\;mm$ suggesting a left ventricular hypertrophy We should note that the PQ segment and ST segment amplitude were higher in athletes than in non-athletes, and they were decreased with exercise in both groups. In particular, the fact that amplitudes of QRS vector in frontal plane or in horizontal plane were significantly greater in athletes than in non-athletes may be an index in evaluating athletes.

• JOURNAL OF ELECTRICAL WORLD
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• s.350
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• pp.98-101
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• 2006

에너지요금의 인상이 잇따르고 있는 가운데‘이란발 쇼크’로 국제유가가 최근 가파른 상승세다. 하루 석유생산량이 390만 배럴로 석유수출국기구(OPEC) 중 사우디아라비아에 이어 두 번째로 큰 산유국 이란. 이 나라의 핵 개발을 둘러싼 국제적인 갈등이 원유공급 감소로 이어질 것이란 우려 때문이다. 미국을 비롯한 EU, 중국, 러시아가 이란 핵의 안보리 회부에 합의한데 따른 시장급변 상황에서 초래됐다. 여기에다 OPEC 회원국들이 지난달 31일 오스트리아 빈에서 열린 정례회의에서 하루 2800만 배럴인 현행 산유량 수준을 고수하기로 합의한 데 따른 파급도 있다. 중동지역의 지정학적인 위기로 인한 수급불안 우려가 해소되지 않고 있는데다 특히 OPEC의 증산 여력이 소진된 상태라는 관측 때문에 유가불안이 고조되고 있는 것이다. 2월초 현재 3월 인도분 서부 텍사스산 원유인 WTI는 배럴당 70달러에 육박하고 있다. 영국 런던 원유시장의 북해산 브렌트유 역시 덩달아 오름세이다. 우리나라에서 주로 수입하고 있는 중동산 두바이유 역시 마찬가지이다. 브렌트나 두바이유도 배럴당 같은 60달러 선이다. 유가 강세는 지난해 가을 허리케인 카트리나의 미국 남동부 강타로 대다수 석유시설이 파괴돼 수급난이 초래돼 WTI 기준 배럴당 한때 80달러에 육박한 이래 하락세를 보이다 이번에 다시 가파른 오름세로 돌아선 것이다.전문가들은 이 같은 유가의 가파른 돌변상황을 심각하게 받아들이고 있다. 1980년 5월 WTI 기준 최고치인 94달러까지 치솟아 오일쇼크를 유발한 국제유가. 이 즈음을 정점으로 내림세로 돌아서 걸프전90~91)으로 반짝 배럴당 50달러에 머문 적이 있다. 이를 제외하곤 1986년부터 2004년까진 10~30달러 선에서 비교적 안정세를 보이다 이후 미국의 이라크 침공을 기점으로 급상승세를 타고 왔다. 지난해 최고 80달러에까지 육박한 국제유가는 하향안정세에서 배럴당 60달러 선에서 등락을 거듭하고 있다. 이 수준도 턱없이 높은 것이다. 이 같은 고유가의 파고가 최근 들어 더욱 심상치 않다는 게 전문가들의 공통된 시각이다. 이번에‘이란발 오일쇼크’가 급습하는 것이 아닌가 하는 우려감마저 갖고 있다. 세계경제 회복세에 발목을 잡을 수도 있다고 보고 있다.본지는 이 같은 고유가의 파고를 넘는 첩경으로 저소비·고효율 기기를 앞으로는 시리즈로 소개한다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.5 no.2
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• pp.8-14
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• 1968

A linear current-pulse discriminator consisting: of a transistor monostable multivibrator and a Si tunnel diode is described. The input currant pulse range is about 50$\mu$A~5.23mA. The measured maximum linearity deviation is $\pm$0.75% in the input current pulse range mentioned above. The pulse resolving ability of the discriminator measured depends upon the bias current through the T, D. ; and, under the reverse bias current of 3mA, the resolving time is 2rs if allow the excess pulse amplitude of 5%. The threshold stability of the discriminator depends mainly upon the stability of the peak current Ip of the T. D. ; and, under the ambient temperature variation from $0^{\circ}C$ to 5$0^{\circ}C$, no bigger threshold variation than the maximum linearity deviation, i. e. $\pm$ 0.75%, was observed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.48-50
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• 2019

항만 및 해안구조물의 안정성이나 연안지형 변화 등에 가장 주요한 외력조건 중 하나인 파랑의 효율적인 관측을 위하여, 선박용 X-band 레이다를 이용항 파랑 모니터링 시스템을 활용할 수 있다. 과거 해외 시스템의 국내 적용시 문제점을 개선한 3S-system (한동대학교 개발)의 건설현장 실적용 사례를 통해 실시간 공간관측 가능한 파랑 시스템 운영을 소개하고, 이를 해상공사 중 작업선박에 대한 관제시스템으로 확장 사용하는 안에 대하여 제시하였다. 향후 추가적인 확장성에 대해서도 공유하고자 한다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.3
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• pp.142-151
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• 2004

A method for the determination of concrete armor unit weights with hydraulic stability and structural stability may be formulated in this paper. The hydraulic stability is analyzed by using Hudson's formula, the structural stability is also studied by evaluation of maximum flexural tensile stresses in armor unit induced by the impact loads and by comparison of those with the tensile resistance strength directly. The applicable criteria for concrete armor units can be represented as a function of design wave heights with return period, armor weights, and tensile strengths for the practical uses. In addition, reliability analyses for two failure modes are carried out to take into account some uncertainties. Finally, a series system for two-failure mode analysis can be made up straightforwardly, by which the optimal weights of armor units can be estimated with the various relative breakages, given the specific target probability of failure under the concepts of reliability-based design method.

• Journal of the Society of Disaster Information
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• v.17 no.1
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• pp.184-193
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• 2021

Purpose: In this study, since the operation principle of the CCFL Exit light is the same as that of general lighting equipment, the characteristics of the CCFL Exit light were analyzed by deriving test items that can affect the characteristics of the light source from the KS standard, which is the standard for lamp ballast performance certification of general lighting equipment. Method: The samples used in the experiment were performed on products of two manufacturers for each size, such as large, medium, and small, and the test items were power factor, crest factor, and current harmonic distortion. Result: As a result of the experiment, the power factor showed a value between 0.4 and 0.6 in all samples, which was smaller than the 0.9 value set by KS. The crest factor ranged from 3.6 to 3.7 for large, 4.4 to 4.7 for medium, and 3.5 to 3.7 for small. It showed a value more than two times higher than the KS standard of 1.7. Current total harmonic distortion ranged from 81% to 110%, and considering that the KS standard was less than 20%, it could be confirmed that all samples had a value significantly exceeding the KS standard. Conclusion: The crest factor and current total harmonic distortion may affect the temperature rise of the light source and the burnout of the device. When developing an exit light, if this item is developed within the scope of the KS standard, the quality improvement and maintenance of the exit light will be greatly improved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.638-644
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• 2008

It is required small size electronic ballast to fullfill the design philosophy of miniaturizing in the application of slim lamps. However, the traditional magnetic ballasts operated at 50-60Hz have been suffered from noticeable flicker, high loss, large crest factor and heavy weight. In this study, in order to solve these problems, It was proposed for driving 35W Class fluorescent lamp in the new type of electronic ballast, which is composed of rectifier, active power factor corrector, series resonant half bridge inverter and piezoelectric transformer. A 35W class(T5 class) fluorescent lamp is driven to successful by the fabricated ballast with piezoelectric transformer. Experimental results, It is proposed to driving the lamp using a electronic ballast at operating frequency of $75{\sim}79kHz$ approximatively. It is operated after for 25 min that were obtained good results of the input power factor of 0.95 and efficiency of 86%, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1033-1039
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• 2012

Artificial joints are used when joints lose their function because of either the destruction or damage of the composing bones of the joints. To evaluate the primary stability of a femur-implant system, the relative displacement caused by a repeated load is measured immediately after the insertion of the artificial joint. For more accurate stability evaluation, the accurate measurement of the penetration displacement of the artificial joint to the bone and the rotation angle of the artificial joint is essential. In this study, to evaluate the primary stability of the femur-implant system, we propose a new relative displacement measurement method. By using this new method, we comparatively evaluate the primary stability for various surgical methods and the varying stiffness of the cadaver femur-implant itself.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.555-560
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• 2014

In Korea, quantitative growth rate of artificial reef construction is supposed to reach the peak point therefore, new approach is needed to the point of artificial reefs business. Functional reefs like shellfish reefs, recreational reefs, seaweed reefs as well as fish reefs are beneficial alternatives. This study conducted hydraulic testing to assess the stability of new types of artificial reefs (ARs) constructed to promote the growth of shellfish and seaweed. The results of this study revealed that some dimensionless design parameters affected the stability of new types of artificial reef under various wave and water depth conditions in the fixed bed condition. The findings also highlight the importance of hydraulic experiments in solving problems that have emerged in the design and construction of artificial reefs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.5327-5332
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• 2014

In Korea, the quantitative growth rate of artificial reef construction is supposed to reach the peak point. Therefore, new approach is needed to the point of artificial reefs business. Functional reefs, such as shellfish reefs, recreational reefs, seaweed reefs, and fish reefs, are beneficial alternatives. This study conducted hydraulic testing to assess the stability of corrugated artificial reefs (ARs) that were constructed to promote the growth of shellfish and seaweed. The results of this study showed that some dimensionless design parameters affected the stability of corrugated artificial reefs under a range of wave and water depth conditions in a fixed bed condition. The findings also highlight the importance of hydraulic experiments in solving the problems that have emerged in the design and construction of artificial reefs.