• Journal of Power System Engineering
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• v.17 no.1
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• pp.64-70
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• 2013

The heat transfer and friction factor characteristics of turbulent flows in three stationary channels have been investigated experimentally to check out the effect of divergence ratio. These are a constant cross-sectional channel and two diverging channels with ratio of divergence(Dho/Dhi) of 1.16 and 1.49. The measurement was conducted within the range of Reynolds numbers from 15,000 to 89,000 and the dimension of uniform cross-sectional test section is $100mm{\times}100mm$ at the cross section and 1,000 mm in length. The measurements of heat transfer coefficients and friction factors in the uniform channels were conducted as a reference. Because of the streamwise flow deceleration, the heat transfer and friction factor characteristics in the diverging channel were quite different from those of the constant cross-sectional channel. The effective friction factors and convective heat transfer coefficients increased with increasing the ratio of divergence of the channel.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.4
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• pp.149-158
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• 2017

In general, the air-side j and f factors of evaporators or condensers are obtained through single-design tests performed under air-dry and wet-bulb temperatures. Considering that the indoor or outdoor air temperatures vary significantly during the operation of an air conditioner, it is necessary to confirm that the experimentally-obtained j and f factors are widely applicable under variable air conditions. In this study, a series of tests were conducted on a two-row slit-finned heat exchanger to confirm the applicability. The results showed that, for the dry-surface condition, the changes of the tube-side water temperature, water-flow rate, and air temperature had virtually no effect on the air-side j and f factors. For the wet condition, however, the f factor was significantly affected by these changes; contrarily, the j factor is relatively independent regarding this change. The formulation of the possible reasoning is in consideration of the condensation behavior underneath the tube. The wet-surface j and f factors are larger than those of the dry surface, with a larger amount for the f factor.

• International Commerce and Information Review
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• v.13 no.4
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• pp.23-49
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• 2011

The of this study was to establish a theoretical basis for relationship marketing exercised in the mB e-Marketplace and to empirically analyze causal relationship among e-CRM factor, together with quality and the performance of the customer relationship. The population sample of this study was the companies who had experience for using the B2B e-Marketplace, and a data analysis was made through y analysis, factor analysis, multiple regression analysis and hierarchical regression analysis, utilizing statistical package of SPSS 18.0. The result of proving the are as follows; First, the e-CRM factors(e-Marketing, e-Service, e-Sales) of B2B e-Marketplace showed the positive influence on the customer relationship quality factor. the e-CRM factors of B2B e-Marketplace showed the positive influence on the customer relationship performance factor. Third, according to the test result on the relationship between quality factor and performance factor, customer relationship quality factor(satisfaction, trust) had positive effect on performance factor. Last, for the moderating effect of switching barrier in the customer relationship quality factor(satisfaction, trust) on the B2B e-Marketplace and its performance factor(reusing intention, long-term orientation) of maintaining the relation, the subordinate variables of switching barrier(alternative attraction, switching cost) showed the positive moderating effects.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.653-664
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• 2011

In this study, I collected materials through the survey whose object is 573 students of technical high schools and 512 students of academic high schools in Seoul and Kyunggi areas, for examining dangerous factors and protective factors which influence on school resilience in technical high schools. The studying results are as followed. First, as the result of analyzing correlation between school resilience and dangerous factor, the higher dangerous factor was, the lower school resilience was. Second, as the result verifying the effects of dangerous factor on school resilience, discrimination of teacher, delinquency bond and anti-sociality made an effect on students in technical high schools and discrimination of teacher, delinquency bond and depression made an effect on students in academic high schools. Third, as the result analyzing correlation between school resilience and protective factor, the higher protective factor was, the higher school resilience was. Forth, as the result verifying the effects of protective factor on school resilience, support of teacher, democratic atmosphere of school, sense of responsibility, family cohesion, self-worth, rational supporting attitude made an effort on students in technical high schools and support of teacher, democratic atmosphere of school, sense of responsibility and family cohesion made an effect on students in academic high schools. Fifth, as the result analyzing the difference between dangerous factor and protective factor according to grade of school and standard of school resilience, there was an interaction in variables of anti-sociality, depression, delinquency bond and self-worth.

• Journal of the Korean Home Economics Association
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• v.40 no.8
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• pp.191-206
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• 2002

The purpose of this study was to explore the effects of adolescent attachment to mothers and peers, self-esteem and impulse control on delinquency. The subjects were 624 eighth and eleventh grade students in Busan. The subjects rated themselves on questionnaires regarding attachment to mothers and peers, self-esteem, impulse control and latent delinquency. The major findings of this study were as follows; 1) Male adolescent delinquency increased with grade. But no grade difference was found in female adolescent delinquency. And male adolescent had more delinquency than female adolescent. 2) Grade had a direct and indirect effect through attachment to peers and impulse control on male adolescent delinquency and was the first positive contribution factor. Impulse control had a direct negative effect on male adolescent delinquency. Attachment to mothers had an indirect negative effect through self-esteem on male adolescent delinquency. Attachment to peers had an indirect negative effect through self-esteem and impulse control on male adolescent delinquency. Self-esteem had an indirect negative effect through impulse control on male adolescent delinquency. 3) Attachment to mothers had a direct and indirect effort through impulse control on female adolescent delinquency and was a first negative contribution factor. Impulse control had a direct negative effect on female adolescent delinquency. Attachment to peers had an indirect negative effect through impulse control on female adolescent delinquency. Grade had an indirect negative effect through impulse control on female adolescent delinquency. Self-esteem had no effect on female adolescent delinquency.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.3
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• pp.50-62
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• 2015

Recently, Subway Line No. 9, described as a 'hell-like' subway for its recorded load factor of max. 240% due to the opening of the 2nd phase extension section, has been causing problems of recurrent congestion in a subway station building. A recurrent congestion in the station building becomes a factor to offend rail users and to reduce the efficiency of railway management. This study aims to establish the methodology for effect evaluation of information provided to rail users, and conducts a gate metering case study considering the congested conditions at a platform among the methodologies for effect evaluation. The metering effect evaluation by load factor was conducted through selecting the micro simulation and pedestrian simulation tool grafting a gate metering. As a result, it was confirmed that, if gate metering is performed, the service level and pedestrian density of a platform by load factor would improve. In other words, if metering is conducted at a platform, it is possible to control the load factor in the waiting space of a platform. Therefore, it was judged through this study that it is possible to set up the index for effect evaluation of information provided to manage congestion of rail users, and establish the methodology for effect evaluation of information provided to rail users through a program.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1302-1308
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• 2010

This study the change of the safety factor before and after the reinforcement were compared by performing the parameter research based on the limit equilibrium analysis regarding the same cross section after carrying out the safety factor before the reinforcement on the virtual section in order to observe the change of the safety factor of the slop reinforced with the slope planting reinforced earth, and the variation of the safety factor according to the increase of the length of the reinforcement materials and the change of the slope height was analyzed. As the result, the reinforcement effect was insignificant at no more than 0.6 of L/H, the reinforcement length ratio when the reinforcement length was increased, as the increase of the safety factor was slow comparing with the non-reinforced slope. At 3.0m of the slope height, reinforcement on the slope is not necessary, and at 3.0m to 5.0m of the slope height, the inclination was not influencing at no less than 0.6 of L/H. At 5.0m to 9.0m of the slope height, the safety factor was mostly secured on the slope at 0.8 of L/H and the over-reinforced slope appeared at no less than 1.0 of L/H. Also, the safety factor increased as the slope height increases and the slope gets steeper till 0.8 of L/H, but the slope steepness affects more on the increase of the safety factor than the reinforcement material, as the reinforcing force by the reinforcement material became steady.

• Journal of the Korean Geosynthetics Society
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• v.15 no.2
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• pp.13-24
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• 2016

The safety factor of an infinite slope tends to be analyzed as lower when the effects of root cohesion are not considered into the equation. Thus, it is essential to consider regional characteristics such as root cohesion and crown density in order to obtain a reasonable safety factor value. In this study, The safety factor of the landslide model, both before and after considering crown density and root cohesion, was calculated and a comparative analysis was carried out. The safety factor is increased by the effect of roots cohesion of the analysis results, the amount of increase in safety factor along the inclination of the slope angle has been analyzed with various things, the effect of reinforcing the roots cohesion, slope of the lower angle it was found that the higher the safety factor increase.

• The Korean Journal of Physiology
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• v.20 no.1
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• pp.103-124
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• 1986

Since it has been suggested that atrial receptor may be involved in the mechanism of extracellular volume regulation, it was shown that the granularity of atrial cardiocytes can be changed by water and salt depletion, and that an extract of cardiac atrial tissue, when injected intravenously into anesthetized rats, was shown to cause a large and rapid increase in renal excretion of sodium. Various natriuretic peptides were isolated and synthetized, and the effects were investigated by many workers. Most studies, however, have been carried out under anesthesia and there have teen some controversies over direct effect of the factor on the renal function. Therefore, it was attempted in this study to access the effects of an atrial extract and a synthetic natriuretic factor in unanesthetized rabbits. Intrarenal arterial infusion of atrial extract caused a rapid increase of urinary volume and excretion of sodium. Glomerular filtration rate and renal plasma flow were both increased with no change in filtration fraction. The ventricular extract produced no change in urinary excretion of electrolytes, nor in renal hemodynamics. Intrarenal infusion of synthetic atrial natriuretic factor caused increases of renal excretory rate of sodium, chloride and potassium, and $FE_{Na}$. Glomerular filtration rate, renal plasma flow increased. And free water clearance also increased. Accentuated excretory function correlated well with increased glomerular filtration rate and renal plasma flow during infusion and for 10 minutes following the cessation of the infusion. Renin secretion rate decreased during constant infusion of atrial natriuretic factor. However, no correlation was found with the changes in glomerular filtration rate, renal plasma flow, or urinary excretion of sodium. These results suggest that atrial extract or atrial natriuretic factor induces changes in renal hemodynamics, as in excretion of electrolytes either indirectly through hemodynamic changes or directly by inhibiting tubular reabsorption. At the same time, renin secretory function is affected by the factor possibly through an unknown mechanism.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.98-103
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• 2001

In case that electronic ballast employing a valley-fill passive power factor correction (PFC) circuit is used for feeding fluorescent lamps, a new method to reduce crest factor of the lamp current is studied in this paper. In order to reduce crest factor to lower value, a pulse frequency modulation technique based on the waveform of the dc-link voltage which is predetermined by the passive PFC circuit, is taken into the switching control action of the electronic ballast. An equation-based analysis between the crest factor of lamp current and the effect of varying the inverter switching frequency is comprehensively performed.