• Journal of Korean Society of Transportation
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• v.33 no.1
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• pp.1-13
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• 2015

This study aims to develop a mainline metering strategy considering queue imbalance among lanes that can reduce congestion at a toll plaza section by managing queue caused by mainline metering. The suggested strategy considers simultaneously optimizing the number of cars in merging area and managing queue by lane. This study analyzes the effectiveness of the strategy with respect to the average travel time and the occurrence rate of spillback using the PARAMICS. The results show that the suggested strategy has an effect on reducing congestion and improving operation efficiency at toll plaza. In particular, the congestion become more intensified when the length of waiting space is shorter; however, this study shows that the suggested strategy can relieve the congestion in that condition.

• Journal of Power Electronics
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• v.18 no.1
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• pp.225-233
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• 2018

This paper proposes a universal system control strategy for voltage source converter (VSC) based high voltage direct current (HVDC) systems. The framework of the designed control strategy consists of five layer structures considering the topology and control characteristics of the VSC-HVDC system. The control commands sent from the topmost layer can be transmitted to the next layer based on the existing communication system. When the commands are sent to each substation, the following transmission of commands between the four lower layers are realized using the internal communication system while ignoring the communication delay. This hierarchical control strategy can be easily applied to any VSC-HVDC system with any topology. Furthermore, an integrated controller for each converter is designed and implemented considering all of the possible operating states. The modular-designed integrated controller makes it quite easy to extend its operating states if necessary, and it is available for any kind of VSC. A detailed model of a VSC-HVDC system containing a DC hub is built in the PSCAD/EMTDC environment. Simulation results based on three operating conditions (the start-up process, the voltage margin control method and the master-slave control method) demonstrate the flexibility and validity of the proposed control strategy.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.125-132
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• 2002

In this paper, a high performance current control strategy for a Brushless DC Motor is presented. The proposed strategy is based on the ramp comparison PI current control with the predictive voltage compensation. The proposed strategy is compared with the hysteresis current control strategy. The proposed method can improve the current waveforms, and it can reduce the torque ripples. So the proposed strategy is suitable to a high performance current control strategy for a Brushless DC Motor. The simulation and experimental results for a laboratory Brushless DC motor drive system confirm the validity of the proposed strategy.

• Journal of Global Scholars of Marketing Science
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• v.3
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• pp.235-251
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• 1999

This research deals with the basic ideas and implementation used for developing competitive advantage in the market they serve. The market to which a company belongs is continuously evolving, not static. Therefore, the company is required to adopt a suitable strategy in the market it serves. Marketing strategy establishment requires continual adjustment in the strategy content and redirection in organizational actions to address emerging market problems and opportunities. Much of the strategic implementation is characterized by firefights aimed at solving emerging, unforeseen problems. The concept of strategy was originally introduced to provide companies with a rational means of coping with environmental changes. An old Oriental proverb said that "knowing myself and then understanding others is the best way to success". In line with the proverb, the starting point of marketing strategy establishment for the competitive advantage is to understand the activities of a company wholly. After analyzing the scope of its activities, a company has to understand the market structure, to review competitive environments, to formulate the base of the competitive strategy and to adopt differentiation strategies for obtaining the competitive advantage.

• Journal of Korean Society for Quality Management
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• v.43 no.3
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• pp.313-326
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• 2015

Purpose: The terminology of "policy" or "quality policy" is widely used in quality management areas. But few people know and use that word with the accurate concept. This paper compares the concepts and suggests the contents for quality policy and quality strategy. Methods: This paper compares the concepts between policy and strategy through the literatures and suggests the contents for quality policy and quality strategy by exploratory study. Results: This paper suggests the contents for quality policy and quality strategy which are useful to establish the quality planning in companies. Conclusion: Strategy and policy are intimately related, and so confused in applications, therefore distinguishing both concepts clearly is necessary for effective use of them. This paper will help the right use of both concepts by showing the examples.

• Journal of The Korean Association For Science Education
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• v.19 no.1
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• pp.107-116
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• 1999

The effects of clarified mapping strategy and placement of analog on middle school students' conceptual understanding were investigated. According to the usage of clarified mapping strategy and the sequence in presenting analogy, four types of learning materials were developed and pilot tested. Prior to the treatment, the field dependence-independence test was administered and a previous achievement test scores were obtained. The scores were used as blocking variables. The learning materials were read by randomly assigned middle school students (N=111), and the conceptions test was administered immediately and four weeks later. In the recall problems of immediate and retention test, there were no significant differences. In the application problems of immediate and retention test, however, the students learned with clarified mapping strategy scored significantly higher than those with analog-only. Field-independent students learned with clarified mapping strategy scored significantly higher in the immediate application than those with analog-only, and higher-level students learned with clarified mapping strategy scored significantly higher in the retention application than those with analog-only. In the immediate application, higher-level students learned analog first with clarified mapping strategy scored significantly higher in the immediate application than those learned target concept first with clarified mapping strategy. However, lower-level students learned target concept first with clarified mapping strategy scored significantly higher than those learned analog first with clarified mapping strategy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.597-602
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• 2014

We determined the effects of starvation, water temperature, and water flow on the onset of metamorphosis in leptocephali of the Japanese eel Anguilla japonica. Leptocephali larger than 50 mm (ca. 200 days old) were reared in 10-L tanks under different feeding, water temperature, and water flow regimes. Fasted leptocephali metamorphosed earlier and faster than did the fed ones. Metamorphosis was faster in the high water flow tank (1.2 L/min) than in the tank with flow at 0.6 L/min. The duration of metamorphosis was slightly shorter at $26^{\circ}C$ than at $23^{\circ}C$. To conclude, starvation induced the metamorphosis of artificially produced leptocephali larger than 50 mm TL. Increased water flow and water temperature both appear to induce and shorten metamorphosis.

• Korean Management Science Review
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• v.26 no.1
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• pp.37-51
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• 2009

Korean IT industry has been given much weight in national R&D management. A negative side of this fact is that Korean economy is likely to become vulnerable to a condition of the export business in certain items of IT industry which has a serious influence on the national economy. A customized investment strategy through the analysis of technology competitiveness and R&D status in each technology of IT field is required in order to rectify the structural vulnerability and pursue a continuous growth. In this research, a strategic direction to set up an efficient investment strategy is presented. In this process, it draws a portfolio analysis with two axes of technology level and technology life cycle. It also derives a priority order of the national investment considering the degree of technological impact, marketability, and adequacy of public support from AHP (Analytic Hierarchy Process) method by a survey of IT experts. A portfolio analysis in the prior stage helps the respondents in AHP become more familiar with the alternatives' characteristics so that their decision making process more corresponds with national R&D strategies.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.6
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• pp.1209-1216
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• 2014

This feeding experiment was conducted to investigate the effects of slurry type diet on growth performance and survival rate of growing leptocephalus, eel larva. We need to find new materials of diets for rearing eel larvae. Test diets were formulated with the eggs of the shark, fish soluble concentrate, soybean peptide and fish protein hydrolysate. Fish (average length 6 mm) were fed 3 slurry type diet(A, B and C) based on shark egg for 5 times per day. During feeding experiment, survival rates were significantly different among 3 slurry type diets. Total protein, lipid, moisture, ash and free amino acids contents were analyzed for slurry type diets. Leptocephalus fed the C slurry type diet was grown up to $38.0{\pm}9mm$ at 150 days. But all leptocephalus fed B slurry type diet were died at 100 days, reaching $16.4{\pm}8mm$. This results suggest that basic information for diet development of eel leptocephalus.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.4
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• pp.369-380
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• 2023

There is no clear standard for estimating the power distribution of fuel cells and batteries to meet the required power in hydrogen electric vehicles. In this study, a hydrogen electric vehicle simulation model equipped with a vehicle electric component model including a fuel cell system was built, and a power distribution strategy between fuel cells and batteries was established. The power distribution model was operated through two control strategies using step control and fuzzy control, and each control strategy was evaluated through data derived from the simulation. As a result of evaluation through the behavior data of state of charge, fuel cell current and balance of plant, fuzzy control was evaluated as a proper strategy in terms of control stability and durability.