• The Korean Journal of Physiology
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• v.1 no.1
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• pp.67-72
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• 1967

Present paper is attempted to introduce the phenomenon of 'after contraction' in isolated cardiac-muscle. Papillary muscles were removed from cat right ventricle and were used as a preparation. The muscle strip was Placed in tissue bath which is kept in steady temperature of around $25^{\circ}C$ and was perfuced by Tyrode solution, saturated with 95% $O_2$ and 5% $CO_2.$ under the condition of high calcium (8.2-10.0 mM/l), low sodium (72.4-70.0 mM/l) perfusion with the administration of epinephrine (1-2 mg/l) into tile tissue bath normally triggered muscle contraction was followed by oscillatory, repetitive contractions - after contraction. The phenomenon of after contraction was augumented by decrease in tissue bath temperature and by increase in number of preceding beats and in driving rate. Authors were able to maintain the phenomenon in prominent and steady state giving proper experimental conditions such as fixed bath temperature (ranged from $22^{\circ}C\;to\;27^{\circ}C$), suitable driving rate (20 per minute in average) and perfusion of high calcium, loll sodium and 1-2 mg/l of epinephrine. In some preparations, the strength of after contraction (second contraction) reached up-to 80% of normally triggered contraction and five repetitive contractions were observed as largest number of after contractions. Intracellular action potential measured in the muscle which was beating regulary showing steady after contraction revealed no oscillating after potential in most parts of the muscle but in few cases oscillating changes of after potentials were detectable. In electrogram of the muscle preparation recorded by means of contact electrode prominent, oscillating after potentials were observable when the recorder was set at highest sensitivity. It still is not clear that whether after contraction is the phenomenon which corresponds to those changes in action potential, oscillating after potential, of the muscle preparation. Possible mechanism of the phenomenon of after contraction relating with after potential changes was proposed. Detailed results obtained from further studies on after contraction and concrete discussion on the phenomenon will be reported by authors.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.2
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• pp.151-160
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• 2017

Growing demand and rapid development of the synthetic fiber rope in mooring system have taken place since it has been used in deep water platform lately. Unlike a chain mooring, synthetic fiber rope composed of lightweight materials such as Polyester(polyethylene terephthalate), HMPE(high modulus polyethylene) and Aramid(aromatic polyamide). Non-linear stiffness and another failure mode are distinct characteristics of synthetic fiber rope when compared to mooring chain. When these ropes are exposed to environmental load for a long time, the length of rope will be increased permanently. This is called 'the creep phenomenon'. Due to the phenomenon, The initial characteristics of mooring systems would be changed because the length and stiffness of the rope have been changed as time goes on. The changed characteristics of fiber rope cause different mooring tension and vessel offset compared to the initial design condition. Commercial mooring analysis software that widely used in industries is unable to take into account this phenomenon automatically. Even though the American Petroleum Institute (API) or other classification rules present some standard or criteria with respect to length and stiffness of a mooring line, simulation guide considers the mechanical properties that is not mentioned in such rules. In this paper, the effect of creep phenomenon in the fiber rope mooring system under specific environment condition is investigated. Desiged mooring system for a Mobile Offshore Drilling Unit(MODU) with HMPE rope which has the highest creep is analyzed in a time domain in order to investigate the effects creep phenomenon to vessel offset and mooring tension. We have developed a new procedure to an analysis of mooring system reflecting the creep phenomenon and it is validated through a time domain simulation using non-linear mooring analysis software, OrcaFlex. The result shows that the creep phenomenon should be considered in analysis procedure because it affects the length and stiffness of synthetic fiber rope in case of high water temperature and permanent mooring system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.2
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• pp.104-111
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• 1997

The freezing phenomenon of saturated water with the supercooled region in a horizontal circular cylinder has been studied experimentally by using the holographic real time interferometry technique. From the experiments, it was found that there were three types of freezing patterns. The first is the annular ice layer growing from the cylinder surface at a high cooling rate; the next is the asymmetric ice layer at a moderate cooling rate; and the last is the instantaneous ice layer growth over the full region at lower cooling rate. As the water was coolde from room temperature to the subfreezing point passing through the density inversion point, the freezing pattern was largely affected by the inversion phenomenon, which had much effected the free convection and was susceptible to influences from the cooling rate. When the cooling rate is high, supercooling energy is released before the water is sufficientry mixed by free convection. On the other hand, when the cooling rate is low, there is much time for the water to be mixed by free convection. This seems to be the reason why the different ice layer growths occur.

• Journal of the Korean Society of Visualization
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• v.8 no.2
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• pp.31-39
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• 2010

Hysteresis is an effect by which the order of previous events influences the order of subsequent events. Hysteresis phenomenon of supersonic internal flows with shock waves has not yet been clarified satisfactorily. In the present study, experiments are carried out on internal flow in a supersonic nozzle to clarify the hysteresis phenomena for the shock waves. Flow visualization is carried out separately on the straight and divergent channels downstream of the nozzle throat section. Results obtained were compared with numerically simulated data. The results confirmed hysteresis phenomenon for shock wave in the Laval nozzle at a certain specific condition. The relationship between hysteresis phenomenon and the range of the rate of change of pressure ratio with time was shown experimentally. The existence of hysteretic behavior in the formation, both the location and strength, of shock wave in the straight part of the supersonic nozzle with a range of pressure ratio has also been confirmed numerically.

• Journal of the Korean Society of Safety
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• v.21 no.3 s.75
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• pp.81-86
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• 2006

The purpose of this study is to examine the effect of column spacing and beam size on the lateral displacement and shear lag phenomenon in bundled tube system. According to the parametric study in which the spacing of columns, the size of columns and girders in bundled tube were selected as a parameter, it is the most efficient to increase the size of the interior columns with the largest reduction of lateral drift if the steel tonnage of a frame can be increased. It was noticed that the shear lag was affected more by the exterior stiffness factor and ratio than by the interior ones when column spacing was changed, and when the size of column was changed, the reverse phenomenon was happened. And The change of column spacing affected shear lag, lateral drift, and tonnage more than that of column size or girder size.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.2
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• pp.25-33
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• 2016

The thermal stratification phenomenon in the nuclear power plant can cause abnormal deformation of the piping, contact with the support, damage to the support system. Repetition of the thermal stratification phenomenon or variation of the thermal boundary layer can cause thermal fatigue. Thermal stratification phenomenon in nuclear power plants is still an ongoing issue and active research has been carried out. In this paper, the current situation in Korean nuclear power plants is described, followed by the status of research and the future problems on the thermal stratification phenomenon in Korea.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2091-2097
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• 2007

This paper described the verification of modeling technique of underground distribution from comparison between field test and simulation. It needs more exact transient phenomenon analysis model to establish lightning protection of underground distribution line. Although, there were a lot of transient phenomenon researches, nobody could has verified the confidence of modeling from field tests in interior until now. So, simulation model verified field test is needed to analyse transient phenomenon of underground distribution system. The examination must be accomplished in many different condition before suggesting these verified analysis model. In this paper, the conditions were examined and the various data results on the different line composition was compared with the EMTP simulation, when the lightning impulse test was accomplished at underground distribution line. Also the value between field test and simulation was very closed and the method of modeling has demonstrated confidence, when the method is used to analyse domestic transient phenomenon of underground distribution.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.2089-2092
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• 2010

There are many cases that interrupt the production process because of malfunctions caused by electronic circuit boards which control equipment, but it is difficult to distinctly identify the causes in many cases. Especially, CMOS devices with the control logic circuit return automatically to normal state after their own faults. Therefore it is not easy to analyze the problems with electronic circuit boards. Recently, nuclear power plant experienced a failure due to the malfunction of electronic circuit boards and it was identified that the reason of the malfunction was because of latch-up phenomenon caused by external surge in electronic devices. This paper presents the causes and the phenomenon of latch-up by experiment and also a way using counter EMF diodes, noise filters and surge protective devices to prevent latch-up phenomenon from electronic circuit boards, finally confirms the effectiveness of the result by experiment.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.984-991
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• 1988

Liquid column separation occurs when the valve on the pipeline is closed rapidly in an oil hydraulic system. In this case two-step pressure rise is sometimes observed in a comparatively short pipeline. In this study the two-step pressure rise phenomenon was investigated experimentally and theoretically. The experiments showed that maximum pressure values during two-step pressure rise might exceed extremely the values computed by the theory of rigid-liquid-column separation. So the two-step pressure rise phenomenon appears one of important factors of pipe strength design. From the theoretical considerations based on the experimental and numerical results, the mechanism of two-step pressure rise phenomenon could be explained clearly.

• Journal of the Korea Fashion and Costume Design Association
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• v.9 no.2
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• pp.167-178
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• 2007

The purpose of this study is to systematically examine fusion phenomenon in the cultural aspect aiming to grasp the characteristics of fusion phenomenon, which has a steady impact on fashion trend. A reason for fusion to be noted as a cultural code is because diversely cultural interpretations are impossible from one viewpoint. Therefore, it is aimed to inquire into the characteristics of fusion culture, which is one phenomenon of newly mass culture, and to examine which cultural fusion phenomenon in modern fashion is being displayed in fashion design. First, the culturally fusion phenomenon, which was indicated in modern fashion, is displayed as repetition. The fusion, which integrates into fashion as a cultural code, is a trend of pursuing the experience with different culture. The needs of consumers are shown as fusion fashion that repeatedly uses the traditional detail and the modern detail through cultural repetition. Second, it is displayed as transformation. A concept of fusion is not the simple aggregate in [1+1=2], but the creation of new culture called [1+1=1]. In modern fashion, the cultures in the East and the West are harmoniously transformed, and through transformation, each culture is being compressively delivered. Third, it is displayed as interdependency. The fusion fashion which was newly re-interpreted while having reciprocal influence upon mutual culture, is re-interpreted by forming the equal relationship in heterogeneous elements without destroying fashion that was made previously.