• Journal of The Korean Association of Information Education
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• v.13 no.4
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• pp.423-432
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• 2009

This study aims to analyze strategy, one of the predictor variables that have influence on the effectiveness of learning in e-learning environment and to define the factors of e-learning strategies of elementary school students. Preceding studies on face-to-face strategy and e-learning strategy, and existing face-to-face and e-learning strategy test sheets were analyzed. Questions are developed based on the results to make clear the area of leaning strategies used by elementary school students in e-learning environment and to analyze the e-learning strategies of elementary school students. The results from this study are, the e-learning strategies of elementary school students are shown in five areas including strategy for learning activity, strategy for learning attitude, resource use strategy, planning strategy, and overload management strategy. It was found that five strategy areas have explanatory power in the order of strategy for learning activity, strategy for learning attitude, resource use strategy, planning strategy, and overload management strategy.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.3
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• pp.328-335
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• 2002

When we want to transfer video streaming data through computer networks, we will have to be allocated a larger bandwidth compared to a general application. In general, it causes a serious network overload inevitably due to the limited bandwidth. In this paper, in order to resolve the problem, we haute taken a method for transmitting video streaming data using RTP and RTCP. With RR(Receiver Report) packet in RTCP we will test it to check whether the traffic in a network has occurred or not. If it happened, we haute tried to reduce the overall network traffic by dynamically changing the quantization factor of the Motion JPEG that is one of the encoding styles in JMF. When the ratio of the average of transmission for each session to the average of overall transmission is greater than 7%, we should adjust the amount of data to be transmitted for each session to reach the session mean values. The experimental results show that the proposed method taken here reduces the overload effectively and therefore improves the efficiency for transmitting video streaming data.

• Toxicological Research
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• v.30 no.4
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• pp.267-276
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• 2014

Exposures to lead (Pb) are associated with neurological problems including psychiatric disorders and impaired learning and memory. Pb can be absorbed by iron transporters, which are up-regulated in hereditary hemochromatosis, an iron overload disorder in which increased iron deposition in various parenchymal organs promote metal-induced oxidative damage. While dysfunction in HFE (High Fe) gene is the major cause of hemochromatosis, the transport and toxicity of Pb in Hfe-related hemochromatosis are largely unknown. To elucidate the relationship between HFE gene dysfunction and Pb absorption, H67D knock-in Hfe-mutant and wild-type mice were given drinking water containing Pb 1.6 mg/ml ad libitum for 6 weeks and examined for behavioral phenotypes using the nestlet-shredding and marble-burying tests. Latency to nestlet-shredding in Pb-treated wild-type mice was prolonged compared with non-exposed wild-types (p < 0.001), whereas Pb exposure did not alter shredding latency in Hfe-mutant mice. In the marble-burying test, Hfe-mutant mice showed an increased number of marbles buried compared with wild-type mice (p = 0.002), indicating more repetitive behavior upon Hfe mutation. Importantly, Pb-exposed wild-type mice buried more marbles than non-exposed wild-types, whereas the number of marbles buried by Hfe-mutant mice did not change whether or not exposed to Pb. These results suggest that Hfe mutation could normalize Pb-induced behavioral alteration. To explore the mechanism of repetitive behavior caused by Pb, western blot analysis was conducted for proteins involved in brain dopamine metabolism. The levels of tyrosine hydroxylase and dopamine transporter increased upon Pb exposure in both genotypes, whereas Hfe-mutant mice displayed down-regulation of the dopamine transporter and dopamine D1 receptor with D2 receptor elevated. Taken together, our data support the idea that both Pb exposure and Hfe mutation increase repetitive behavior in mice and further suggest that these behavioral changes could be associated with altered dopaminergic neurotransmission, providing a therapeutic basis for psychiatric disorders caused by Pb toxicity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.495-503
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• 2019

The purpose of this study was to investigate the general characteristics, work overload, work life balance, job engagement of working adolescents and the factors affecting job engagement. We examined 1,772 working adolescents under the age of 24 years in response to the fifth Korean Working Conditions Survey. Technical statistics, t-test, ANOVA, and regression analysis were used. The study results showed that men had high-level job engagement when they were professional, self-employed, 41-52 hours per week, and never experienced employment discrimination. For women, job engagement was high if they were under 19 years of age, college graduates, professions, temporary work, 41-52 hours a week, and had never experienced gender discrimination, and employment discrimination. In addition, the job engagement of both men and women was higher when work overload was less and work life balance was good. This study is meaningful in that it examined the job engagement of working youth by using the Korean Working Conditions Survey representative of Korean workers. However, it has limitations in that it does not take into account specific circumstances such as academic status or military service. Based on the study results, it can be used as basic data for developing educational programs to manage job engagement and understanding of working adolescents.

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.376-380
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• 2006

Temperature distribution measured to estimate the condition of an electrical apparatus is an absolute reference for the apparatus conditions and the difference between the reference temperature and the current temperature. Because of passive thermography, without the external thermal stimulation, the difference in surface temperature between the region of interest and back ground shows that the results can apply only to the estimation or the monitoring for the condition of loose terminal and the overload pertaining to the rise in temperature. However, a thermal diffusion in the active thermography is differently generated by the structure and condition of the surface and subsurface. This paper presents a nondestructive test using this behavior and deals with the results by heat injection and cooling to the apparatus. The buried discontinuity of subsurface could be detected by these techniques.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.607-612
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• 2002

This paper presents the first domestic model product of hybrid Insulation low-loss type pole transformer, with increased overload ability, increased life, reduced loss, focusing improved short-circuit characteristics. The capacity of this transformer is 100 KVZ, rates first voltage 13200 V and secondary voltage 230/115 type. The volume of model transformer that was produced in high temperature using hybrid insulation can be reduced to 10-20% in comparison with that of present transformer with the same capacity. In this paper, we did short-circuit test and tested general characteristics of model transformer. In addition, we suggested design application new concept and methods thorough this experiment.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.292-295
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• 1991

The life of the transformers is significantly dependent upon the rate of thermal deterioration in the employed insulating materials. Therefore, the study should be based on hot-spot temperature considerations for the life expectancy and possible overload of transformer. We have measured directly temperature of the winding using thermocouples and these test results are compared with those obtained from computer simulation. In this work, our fundamental investigations are well described for the analysis in the thermal distribution of the oil-immersed transformer with the rating of 30kVA.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.4
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• pp.67-77
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• 2002

This paper introduces the calibration results of the fatigue crack growth models for damage tolerance analysis of the aircraft structures. Generalized Willenborg model and Wheeler model are calibrated with experimental data tested under the load spectrum of a trainer. The retardation factors such as, shut-off ratio in Generalized Willenborg model and shaping exponent in Wheeler model, are evaluated for aluminum alloys AL2024-T3511, AL7050-T7451 and AL7075-T73511. It is shown that the retardation effect of the crack growth rate depends on the yield strength of material and the maximum stress in the load spectrum. Generalized Willenborg model and Wheeler model give satisfactory prediction of crack growth life but the calibration of the experimental parameters with test is required.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.461-468
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• 2005

The D-ROG(Digitalized Restoring of Grouting) Method is the restoring method for structures subjected to differential settlement and tilting by means of high grout injection pressure. This study investigate effect of grouting through in field test which applied D-ROG method in different condition(overload, ground condition).

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.286-290
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• 2007

In this paper, a new algorithm based on sensitivity method for alleviating overloads in power networks is presented to find the switching branches effectively. Preferentially the switching of shunt reactive devices such as shunt reactor and shunt capacitors is performed. If overloads are not eliminated, the ranking of switching branches is calculated according to the algorithm based on sensitivity method and the switching of the ranked branches is performed in the order of ranking until overloads are eliminated. In order to show the effects of this algorithm, it is applied to a small scale power system of IEEE 39-bus test system.