• Journal of the Korea Safety Management & Science
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• v.4 no.4
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• pp.109-118
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• 2002

Such effects would be paid off in the right way only when management of the firms perform marketing activities focusing on long term effectiveness, which would drive company profits up and keep them for long. Demands of customers are being changed and varied. In this result with the advantage of mass marketing and database marketing have been drawing attentions from company. To fulfill these demands of customer, they need a concept of eCRM(Web based Customer Relationship Management), and go from selling products and services, or gathering customer requests, up to the phase of solving customer's problem by real time or previous action. With the help of internet, the frequency and speed of the problem solving has improved greatly. For these purposes, we try to determine the most important and most urgent factors in eCRM: utilization by using SN Ratio Decision making, one of the Multi-criteria decision-making methods SN Ratio Decision making is widely used for determining relative magnitude per evaluation item, i. e. priority on problems and is expected to make more systematic and objective evaluations than conventional methods do. Even in the present situation where any general criterion on eCRM dose not exist, utilization of eCRM is expected to be actively continued, which will cause many problems. In this regard, evaluating eCRM counts.

• Journal of IKEEE
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• v.21 no.4
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• pp.416-419
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• 2017

In this paper, we propose a new digital delay-locked loop (DLL) for high-speed DDR3/DDR4 SDRAMs. The proposed digital DLL adopts a fine delay line using phase interpolation to eliminate the jitter increase problem due to the boundary switching problem. In addition, the proposed digital DLL utilizes a new gradual search algorithm to eliminate the harmonic lock problem. The proposed digital DLL is designed with a 1.1 V, 38-nm CMOS DRAM process and has a frequency operating range of 0.25-2.0 GHz. It has a peak-to-peak jitter of 1.1 ps at 2.0 GHz and has a power consumption of about 13 mW.

• Journal of the Optical Society of Korea
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• v.20 no.6
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• pp.704-715
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• 2016

In this paper, we explore a low-complex bandwidth allocation (BA) scheme with multi-level service guarantees in VLC-OFDM systems. Effective capacity theory, which evaluates wireless channel capacity from a novel view, is utilized to model the system capacity under delay QoS constraints of the link layer. Since intensity modulation of light is used in the system, problems caused by frequency selectivity can be neglected. Then, the BA problem can be formulated as an integer programming problem and it is further relaxed and transformed into a concave one. Lagrangian formulation is used to reformulate the concave problem. Considering the inefficiency of traditional gradient-based schemes and the demand for distributed implementation in local area networks, we localize the global parameters and propose a quasi-distributed quadratic allocation algorithm to provide two-level service guarantees, the first level is QoS oriented, and the second level is QoE oriented. Simulations have shown the efficient performance of the proposed algorithm. The users with more stringent QoS requirements require more subcarriers to guarantee their statistical delay QoS requirements. We also analyze the effect of subcarrier granularity on the aggregate effective capacity via simulations.

• Journal of Korean Elementary Science Education
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• v.31 no.1
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• pp.13-24
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• 2012

This purpose of this study was to analyze the characteristics of elementary students' argumentation in science problem solving process. For this study, the two argumentation topics were developed on the basis of Williams and Colomb's argumentation model. The topics of argumentation were the weight of the air and the change of volume according to state of water. The participants of this study were 6th grade students (n=51). Data were analyzed by Williams and Colomb's argumentation model and Kienpointner's argumentation style. The results of this study were as follows: In the argumentation model, most of students had the factors of claim, reason, evidence/data in their statements. But low-achievement students had difficulty in warrant and acknowledge & response. In argumentation style, the frequency of the cause-effect and explanation of example style were higher than other argumentation styles. Some implications were suggested, such as understanding the characteristics of elementary students' argumentation activities and need of educational programs including scientific argumentation.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.3
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• pp.231-239
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• 1999

An improved version of current-regulated delta modulator (CRDM) is investigated for the output cunent control of v voltage-source inverters that have transformer-coupled series resonant load and are operated at the resonant frequency. Conventional CRDM has not only CUlTent offset problem but also transformer flux saturation problem when i it is applied to induction heating systems that have transformel-coupled loads. To cope with these problems, the effect of flux saturation is analysed, and simple method to av이d the problem is proposed. And integral type of CRDM is a adopted to remove the cunent offset. The boundaries of integrator gain for stable operation is calculated using the c concept of sliding mode controL The validity of proposed strategy is vel퍼ed through simulations and prototype e experiments.

• Journal of Power Electronics
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• v.10 no.6
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• pp.595-603
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• 2010

In this paper, teaching in a "switching converter (SC) design" course using problem-based learning (PBL) with dynamicbehavior- model simulation, given at Lunghwa University of Science and Technology (LHU), Taiwan, is proposed. The devised methodology encourages students to design and implement the SCs and regulate the controller's parameters in frequency domain by using 'sisitool' ('bode') in the MATLAB toolbox. The environment of PBL with converter characterization modeling and simulation reforms the learning outcome greatly and speeds up the teaching-learning process. To qualify and evaluate the learning achievements, a hands-on project cooperated with the continuous assessment approach is performed to modulate the teaching pace and learning direction in good time. Results from surveys conducted in the end of the course provided valuable opinions and suggestions for assessing and improving the learning effect of the proposed course successively. Positive feedbacks from the examinations, homework, questionnaires, and the answers to the lecturer's quizzes during class indicated that the presented pedagogy supplied more helpfulness to students in comparisons with conventional teaching paradigm, their learning accomplishments were better than expected as well.

• Journal of Korean society of Dental Hygiene
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• v.21 no.2
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• pp.109-118
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• 2021

Objectives: This study aimed to investigate the association between interpersonal relationships and the 4C core competencies of dental hygiene students. It also examined how interpersonal competence can be enhanced by the development and application of programs so that the 4C core competencies of university students can be improved. Methods: A survey was conducted from March to May 2019 on students from the Department of dental hygiene in Busan, South Korea, and 177 valid responses were analyzed. The general characteristics of the students were calculated using frequency and percentage, and their degree of 4C core competencies and interpersonal abilities were expressed as means (±standard deviation). Multiple regression analysis was used to analyze the effects of interpersonal competence on the 4C core competencies. Results: The findings revealed the factors affecting the 4C core competencies as; (a) communication ability was affected by interpersonal cognition and confidence building; (b) critical thinking ability was affected by person-oriented, self-expression, and confidence building; (c) creative problem-solving ability was affected by self-confidence, person-orientation, self-expression, and confidence building, and (d) cooperative self-efficacy was affected by person-oriented and confidence building. Conclusions: Based on the above findings, it is necessary to develop systematic program items and education systems that can effectively develop interpersonal competency, and thereby improve 4C core competencies among students.

• Journal of Family Relations
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• v.20 no.4
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• pp.105-130
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• 2016

Objectives: The purpose of this study was to explore the moderating effect of stress coping styles on the relationships between loss experiences and depression of the men and women elderly. Method: The subjects of the study were 116 men and 156 women aged over 60 years. For the data analysis, frequency, Cronbach's ${\alpha}$. Pearson's correlation coefficients, and multiple regression were used. Results: The main results were as follows: First, elderly men reported higher role loss experience, relation loss experience, and problem-focused coping styles than elderly women. Also elderly women reported higher bereavement experience than elderly men. Second, there were main effects of health loss experience, economy loss experience, role loss experience, relation loss experience, problem-focused coping style, and emotion-focused coping style on depression of elderly men and women. Third, problem-focused coping styles moderated the relationships between physical health loss experience, economy loss experience, role loss experience and depression in the elderly men group. Last, social support-seeks coping styles moderated the relationships between economy loss experience and depression in the elderly women group. Conclusions: These results were discussed in terms of educational programs related stress coping strategies for the elderly.

• Human Ecology Research
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• v.59 no.4
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• pp.433-448
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• 2021

The purpose of this study was to analyze two subject competencies (practical problem-solving capability and independent life capability) reflected in the activity tasks included in the 'home life and safety' area of 12 middle school technology-home economics textbooks in accordance with the 2015 revised curriculum. The analysis criteria were sub-elements of two subject competencies. Seven sub-elements were derived from each competency. Frequency analysis was performed to determine how often the sub-elements were reflected in the activity tasks. The results were as follows. First, with regard to the sub-elements of 'practical problem-solving capability', 'value judgment' was reflected most frequently in the activity tasks followed by 'exemplification of solution', 'logical thinking', 'critical thinking', 'decision-making', 'practical reasoning', and 'evaluation of solutions'. Secondly, the sub-elements of 'independent life capability' were unevenly distributed in the activity tasks. The 'capability to perform conscious living' was reflected most frequently followed by 'development and self-identity', 'time, money, and leisure management', and 'reasonable consumption and resource utilization'. For teachers wanting to teach activity-oriented classes and student participatory classes, the results pinpoint the materials necessary to develop learners' subject competencies by using textbooks from different publishing companies.

• Journal of Power Electronics
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• v.13 no.2
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• pp.197-205
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• 2013

In energy injection resonant AC-AC converters, due to the low frequency effect of the AC input envelope and the low energy injection losses requirement, the constant and steady control of the high frequency AC output envelope is still a problem that has not been solved very well. With the aid of system modeling, this paper analyzes the mechanism of the envelope pit on the resonant AC current. The computing methods for the critical damping point, the falling time and the bottom value of the envelope pit are presented as well. Furthermore, this paper concludes the stability precondition of the system AC output. Accordingly, an optimal control method for the AC output envelope is put forward based on the envelope prediction model. This control method can predict system responses dynamically under different series of control decisions. In addition, this control method can select best series of control decisions to make the AC output envelope stable and constant. Simulation and experimental results for a contactless power transfer system verify the control method.