• Proceedings of the KSCN Conference
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• 2007.10a
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• pp.256-256
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• 2007

• KOREAN POULTRY JOURNAL
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• v.12 no.2 s.124
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• pp.52-54
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• 1980

• Journal of Life Science
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• v.28 no.8
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• pp.985-991
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• 2018

Biological clocks are the basis of temporal control of metabolism and behavior. These clocks are characterized by autonomous free-running oscillation and temperature compensation and are found in animals, plants, and microorganisms. To date, various biological clocks have been reported. These include clocks governing hibernation, sleep/wake, heartbeat, and courtship song. These clocks can be differentiated by the period of rhythms, for example, infradian rhythms (> 24-hr period), circadian rhythms (24-hr period), and ultradian rhythms (< 24-hr period). In yeast (Saccharomyces cerevisiae), at least five different autonomous oscillations have been reported; (1) glycolytic oscillations (T = 1~30 min), (2) cell cycle-dependent oscillations (T = 2~16 hr), (3) ultradian metabolic oscillations (T = 15~50 min), (4) yeast colony oscillations (T = a few hours), and (5) circadian oscillations (T = 24 hr). In this review, we discuss studies on oscillators, pacemakers, and synchronizers, in addition to the application of biological clocks, to demonstrate the nature of autonomous oscillations, especially ultradian metabolic oscillations of S. cerevisiae.

• Development and Reproduction
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• v.7 no.1
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• pp.1-7
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• 2003

Most animals, including human beings, live in a cyclic pattern of lift that is influenced by the ambient changes of environment. The regular changes occurred by rotation of the Earth itself its revolving around the Sun, and the local environment, are reflected by the distinct behavior in the living organisms. These regular changes of environment have been imprinted into the genes within the living organisms through the evolutionary process over a long period of time. The genes are expressed by rhythms during the process of fetal development followed by growth. The environmental modifications ultimately are settled in genes, serving as a biological clock that is located putatively in the hypothalamus. Thus the biological clock governs a large number of rhythms and affects the time of birth and death lift expectancy, behavior, physiology, cell division, biochemical reaction, etc. The rhythms are readjusted to the changes of environmental cues. The biological clock has the great advantage of predicting and preparing the regular changes of environment.

• Journal of Photoscience
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• v.9 no.2
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• pp.9-12
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• 2002

Circadian rhythms can be seen in a variety of physiological functions in insects. Light is a powerful zeitgeber not only synchronizing but also modulating the rhythm to adjust insect's temporal structure to seasonal changes in the environmental cycle. There are two general effects of the length of light phase within 24 hr light cycles on the circadian rhythms, i.e., the modulation of free-running period and the waveform. Since the photoperiodic modulation of the free-running period is induced even in the clock mutant flies, per$\^$s/, the free-running period is not fully determined genetically. In crickets, the ratio of activity (a) and rest phase (p) under the constant darkness (DD) is clearly dependent on the photoperiod under which they have been kept. When experienced the longer photoperiod it becomes smaller. The magnitude of change in a/p-ratio is dependent on the number of cycles they experienced. The neuronal activity of the optic lobe in DD shows the a/p-ratio changing with the preceding photoperiod. These data suggest that a single circadian pacemaker stores and maintains the photoperiodic information and that there is a system that accumulates the effects of single photoperiod to cause greater effects.

• Development and Reproduction
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• v.12 no.1
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• pp.9-18
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• 2008

All the organisms on the earth are affected by the repeating signals from the ambient environment caused by the movements of the sun and the earth. Their physiological and behavioral activities such as reproduction, functional pathway of various molecules, and developmental stage, are reflected by the cyclicity whether it is daily(circadian) or annual rhythms. An essential function of circadian rhythms is to provide an internal estimate of the external local time, thereby allowing the organism to program its activities so that they occur at an appropriate time in the daily environment. Of many rhythmic patterns, the circadian rhythms are considered in this review, focusing on the limit cycle, which is a model to investigate the entrainment.

• Fisheries and Aquatic Sciences
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• v.4 no.3
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• pp.130-137
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• 2001

In the present study, the locomotor and feeding activities of single red sea bream, Pagrus major were simultaneously investigated to examine the existence of such dual behaviour. Seven red sea bream of 13cm body length on average were placed individually in 35L tanks equipped with an infrared sensor and a newly developed demand-feeding device. Fish were exposed to a light: dark 12: 12h cycle and constant darkness (DD) to study endogenous rhythmicity. Under LD 12: 12 h, the daily pattern of behaviour differed between individual fish; some red sea bream were diurnal and others were nocturnal. Futhermore, some of them displayed an extraordinary flexibility in phasing because they were dark active but light feeding, and vice versa. Under DD, red sea bream showed free-running rhythms for locomotor activity and feeding. These results indicate that the type of phasing of locomotor activity did not necessarily decide the feeding phase; much of this is explained by the fact that red sea bream were demand-fed. Flexibility in phasing and a certain degree of independence between locomotor and feeding activities could be seen as an adaptative response of the highly adaptable circadian rhythms of fish.

• Korean Journal of Oriental Medicine
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• v.7 no.1
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• pp.85-103
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• 2001

Objectives : Assuming that the characteristic of meridian system has been similar to this of electric potentials in human body and that measurements of electric potential at well(井穴) and sea(合穴) points in branches of the twelves meridians will be representative of measurements of the twelve meridians, to measure the electric potentials in twenty aged(TAG) and fifty aged(FAG) healthy volunteers groups when they were sleeping or awakening respectively, to do significance test for electric potential of meridian system among circadian rhythms(CR) and Sasang constitutions(SC). Methods : We selected who thirty healthy volunteers were diagnosed by a blood test, urine examination and differentiation of syndromes by five viscera among volunteers. When they were sleeping, their electric potentials of well and sea points in branches of the twelve meridians were simultaneously measured by physiograph. After a minute we measured them again, totally 5 times. And then when they were awakening, their electric potentials were measured 5 times by the above method. Results : Measurements were analyzed by statistical ANOVA test, we obtained that some of the electric potentials of TAG at sleeping significantly varied with CR, SC, and at awakening some of the electric potentials of FAG also significantly did with CR, SC.

• Sleep Medicine and Psychophysiology
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• v.5 no.1
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• pp.12-17
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• 1998

Circadian rhythms in subjective alertness, mood, and performance can be classified as psychological rhythm, compared with physiological rhythm such as body temperature and hormonal change. While in normal condition entrained by 24hr zeitgeber, subjective alertness would reach its maximum value around midday, subjective alertness would parallel body temperature rhythm with its peak at evening in non-entrained, free-running state. With desynchronization technique, subjective alertness rhythm is thought to be controlled by both temperature and sleep-wake rhythm oscillator. Circadian performance rhythms depend on the kind of task tested. It shows parallelism with body temperature rhythm when subjects are tested with simple, repetitive task. But when tested with tasks requiring complex verbal reasoning or immediate memory, subjects would perform them best at early morning, with performance decreasing as time of day advances. The desynchronization technique shows that circadian performance rhythm of simple, repetitive task is dependent on temperature oscillator but circadian performance rhythm of complex verbal reasoning is influenced by both temperature and sleep-wake rhythm oscillator or another independent oscillator. It would be worthwhile to compare psychological rhythm with hormonal change such as cortisol and melatonin. And more simple and time-saving method than desynchronization technique may facilitate the study of the mechanism underlying psychological rhythm.

• The Korean Journal of Emergency Medical Services
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• v.26 no.1
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• pp.7-19
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• 2022

Purpose: The purpose of this study is to evaluate the interrupted chest compression time during the use of an automated external defibrillator (AED) depending on different AED practice training methods, and to report differences in self-efficacy before and after training. Methods: We enrolled university freshmen who have had cardiopulmonary resuscitation (CPR) training but have not or have had AED training but over 6 months. We examined differences between the group that practiced only shockable rhythms during training and the group that practiced both shockable and non-shockable rhythms. Results: A total of 72 individuals participated in this study, with 36 individuals each in the control and experimental groups. There was no statistically significant difference in the proficiency of AED usage between the two groups. In non-shockable cases, the experimental group showed shorter chest compression interruption time than the control group (2.30±1.21sec vs. 3.16±1.73 sec; p<0.01). In terms of self-efficacy before and after training, both groups showed higher self-efficacy after than before training. Conclusion: Individuals who underwent training that provided practice on both shockable and non-shockable rhythms had a shorter interrupted chest compression time when using the AED.