• KIEE International Transactions on Power Engineering
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• 제2A권3호
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• pp.83-88
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• 2002

An over current relay(OCR), one of the most frequently used protective devices, has time-current characteristics (TCC) to control its trip time according to the current level. It is because an appropriate operating time interval is necessary for coordination with other protective devices. A set of TCC curves of an OCR is, in general, given by the supplier from which a curve is selected by the operator. Therefore, in many cases, it is impossible to consider the operation condition of the given power system exactly. A novel concept of an OCR is suggested in this paper. The proposed OCR has an internal correction module so that it may produce the most adequate TCC curve according to the given protective information for coordination with other devices. With the generated TCC curve, a variety of operation and coordination conditions can be taken into consideration in an effective manner. The suggested OCR is applied to a simple test power system to show very promising results from a coordination point of view.

• 한국정보시스템학회지:정보시스템연구
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• 제23권4호
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• pp.49-74
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• 2014

The introduction of smartphone caused the most revolutionary change in the domestic telecommunications market after the digital revolution. However, due to the saturation of the local market, it is expected to post negative growth in 2016 and the sales of national communication carriers is in stasis. Thus, the smartphone industry is starting to shift its marketing efforts to secure the silver generation who still has room for increase in the rate of smartphone usage. As the silver generation has physical limitations and differences in needs, the marketing strategy based on the smartphone utilization is not appropriate. This study suggests the new silver generation, who has high income level and similar characteristics to the younger generation, as the new customer segment for smartphone. We analyze the effects of the major variables of UTAUT on smartphone use, as well as examine how these relationships differ between the new silver and the net generation. We verified the hypotheses using a survey with 309 smartphone users. The research findings supported the hypotheses regarding the effects of performance expectancy, effort expectancy and facilitating conditions on smartphone use, but did not support the hypothesis on the effect of social influence. The result of the group comparisons showed that both generation have similar characteristics on innovativeness and cognitive absorption, but the moderating effect of age on performance expectancy, effort expectancy and use is stronger in conjunction with the new silver generation. The study results are expected to be used in establishing a marketing strategy for the new silver generation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.29-32
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• 2008

Testing was conducted to determine the performance of a residential fuel cell system when subjected to DSS and WSS operation, especially for start-up and shut-down characteristics. In terms of start-up time, it took about 70min to start output power generation and stably to reach 1kW at cold start. Measurement of the characteristics of heat and power generation were carried out at start-up and shut-down time. Fuel gas is used for heating both reformer and stack from start-up to the beginning of power generation. In terms of start-up and shut-down characteristics, it was important to control the reformer temperature precisely. The average output water temperature during the rated output operation(960W) was $63.2^{\circ}C$ constantly. The results of the investigation are being used to develop a new test protocols for residential fuel cell system.

• 전기학회논문지
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• 제56권5호
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• pp.933-937
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• 2007

A point plate type nonthermal plasma reactor, with a grounded cylindrical third electrode which closely- encompasses the needle point, have been investigated with an emphasis on the role of the third electrode. It was found that the point plate airgap, with the grounded third electrode, had a switching characteristic on its I V characteristics for negative and positive discharges, which is very different from that of a conventional point plate airgap without a third electrode. The corona discharge and ozone generation characteristics of the plasma reactor with the grounded cylindrical third electrode, such as the corona onset voltage. the breakdown voltage. the corona current. and the amount of output ozone, were influenced significantly by the height of the third electrode. and these characteristics can be controlled by adjusting the height of the third electrode.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.662-667
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• 2000

A simulation procedure for a full transient analysis of the start-up of heavy-duty gas turbines for power generation is constructed. Compressor stages are grouped into three categories (front, mid, rear) and three different stage characteristic curves are applied to consider the different low-speed operating characteristics. Start-up behavior of a typical single-shaft gas turbine for power generation is simulated. The predicted transient behavior shows a good agreement with the field data. Special attention is paid to the effects of the modulation of VIGV on start-up characteristics, which play a key role in the stable operation of gas turbines.

• 전력전자학회논문지
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• 제21권6호
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• pp.481-485
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• 2016

When analyzing economic feasibility for installing a PV generation plant at a certain location, the prediction of possible annual power production at the site using the target PV panels should be conducted on the basis of the local weather data provided by a local weather forecasting office. In addition, the prediction of PV generating power under certain weather conditions is useful for fault diagnosis and performance evaluation of PV generation plants during actual operation. This study analyzes PV cell characteristics according to a variety of weather conditions, including ambient temperature and irradiance level. From the analysis and simulation results, this work establishes a proper model that can predict the output characteristics of PV cells under changes in weather conditions.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.559-562
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• 2000

The problem of noise generation due to PWM switched-mode power converter has been widely noticed from the viewpoint of Electromagnetic Interference(EMI). Many kings of topologies for resonant converters have been developed both to overcome this noise problem and to attain high power efficiency. It is reported in references that resonant converters which are derived from PWM converter using resonant switch show much lower noise characteristics than PWM converter, and that current-mode resonant converter is more sensitive to stored charge in rectifying diode than voltage-mode counterpart concerning surge generation at diode’s turn-off. On the other hand, above mentioned resonant converters have defect of high-voltage stress on semiconductor switch and complicated circuit configuration. Hence, the simplified Forward-type resonant converter has been proposed and investigated due to its prominent features of simplicity of circuit configuration, low voltage stress and high stability. However, its noise characteristics still remain unknown. The purpose of this paper is to study quantitatively the noise characteristics of this simplified Forward-type resonant converter by experiment and analysis. The influence of parasitic elements and stored charge in rectifying diode on noise generation has been clarified.

• Journal of information and communication convergence engineering
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• 제19권4호
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• pp.205-213
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• 2021

The properties of a scale-free network are little known; its node degree following a power-law distribution is among its few known properties. By selecting real-field scale-free networks from a network dataset and comparing them to other networks, such as random and non-scale-free networks, the topology characteristics of scale-free networks are identified. The assortative coefficient is identified as a key metric of a scale-free network. It is also identified that most scale-free networks have negative assortative coefficients. Traditional generation models of scale-free networks are evaluated based on the identified topology characteristics. Most representative models, such as BA and Holme&Kim, are not effective in generating real-field scale-free networks. A link-rewiring method is suggested that can control the assortative coefficient while preserving the node degree sequence. Our analysis reveals that it is possible to effectively reproduce the assortative coefficients of real-field scale-free networks through link-rewiring.

• 한국의류산업학회지
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• 제15권3호
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• pp.358-363
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• 2013

Due to recent changes in increased life expectancy, economic power and social development, the new senior generation (focusing on people in their fifties) represents a new market power with strong competitiveness. The new senior generation is the generation after the baby boomers, with characteristics that include a high-level of education, increased income, a high-level of consumption, increased assets, self-fulfillment desires and individuality. Demands in the senior fashion industry are expected to gradually increase and the underwear industry that targets the new senior generation is expected to grow rapidly. These demands will require product development for the new senior generation based on emotional and socio-cultural characteristics. The current new senior underwear market is under the process of R&D with a focus on body shape changes; however, there are limited studies on emotional and socio-cultural approaches. This study formulates a basic design plan for different age groups based on an analysis of the situation of bra wear (current inconveniences, demand and needs) by women in their fifties and over. Subsequently, a functional active bra top that considers activity and comfort was proposed for women in their fifties, an all-in-one foundation bra top that shapes the body was proposed for women in their sixties, and comfort bra tops that are comfortable and easy to put on and take off were proposed for women in their seventies and over.

• 한국의류학회지
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• 제19권4호
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• pp.615-627
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• 1995

The purpose of this study is to identify the difference of value and clothing behavior by generation, and to suggest a [device for family concord by overcoming a generation gap. Data was obtained from 106 families(daughter, mother, and grandmother in one family), of which the daughter was attending Ewha Womans University. And it was analyzed by ANOVA, Duncan.test, x2_test, ANCOVA ant two-way ANOVA. The results of this study were as follows. 1. Each generation showed different values. Mother and grandmother perceived greater importance for each value except political value. 2. Each generation has its own clothing behavior characteristics. Style, silhouette, skirt length, and neckline preferrences were different by generatiorts. In general, mothers and grandmothers showed si mil ar characteristics. Wearing size and subjective feeling for suitability were also different by generation. Finally in consumption behavior, preferred clothing price and expenditure were also differed by generation.