• Educational Technology International
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• v.10 no.2
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• pp.127-143
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• 2009

The purpose of this study was to identify the interaction patterns in distance only mode e-Learning. In order to investigate this study, messages shown in the electronic notice board were analyzed to see how interaction occurs between teacher and learner or learner and learner under the e-learning of cyber university. To analyze messages was applied according to the framework by Henri's contents analysis model. As a result of contents analysis on electronic board, the participative dimension was 399 messages. A learner put on 7~8 messages a day. The number of messages was low compared to the number of learners, but the number of inquiries was about 140. That means that each learner contacts and checks messages at least once a day. The meaning dimension was 600 units. The main interaction patterns were Interactive-social-cognitive-metacognitive. This means that e-Learning in distance only mode leads a positive attitude of learners as a self-directed learning, and needs teacher's well-structured instructional strategies for increasing interaction. In conclusion, social dimension and interactive dimension of messages support learners psychologically in the process of learning though they directly guide learning under the circumstances of e-learning lacking face-to-face element. It can be interpreted that the teacher's role is significantly important in order to attract learners' positive participation and cognitive and meta-cognitive dimension of messages and activities

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.43-48
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• 2008

Through simulations and field experiment on A.C. parallel operation of both Utility Interactive Photovoltaic System and Diesel Engine Revolving Field Type Synchronous Generator, following factors have been found. First, the inverter should be operated in three modes of frequency(mode.1: ${\pm}$0.3Hz, mode.2: ${\pm}$1Hz, mode.3: ${\pm}$2Hz) as default, considering properties of operating Synchronous Generator. Second, as a result of supplying 13.5kW of residual power, it has been found that Synchronous Generator takes the power input only as reactive power, because it was electrically stable with frequency of 60.14Hz and high voltage of 222.3V even when power factor was -0.94. Besides, it was mechanically stable, too, because the quake, noise, and temperature of Synchronous Generator in this case were 7.5mm/s, 97dB, and $6^{\circ}C$ respectively, which were lower than normal load connection of 145.6kW; 11.03mm/s. Thus, load share of Revolving Field Type Synchronous Generator reduces according to the supply of Photovoltaic System to the load power. In this experiment, 200kW of Synchronous Generator and 40kW of Photovoltaic System were operated in parallel. The load share was 20% in maximum. and 11.1lit/hr of fuel was saved.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.2
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• pp.227-234
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• 2012

Development of Computer science and internet technoloy have led changes all over the social area. Educational markets based on this circumstance are offering various services named remote education, cyber lecture, e-Learning, etc. Due to these products, systems for computer based teaching and evaluating student's achievement are wide spread. But in many systems we can find functional restrictions. In this paper we propose a RTE system offering interactive self control mode based education so as to provide customized education for each individual by realtime feedback of the level of the student's comprehension we expect that this system provides customized education environment considering student's achievement level and maximizes their motivation.

• Journal of Digital Convergence
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• v.19 no.6
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• pp.343-353
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• 2021

The beauty industry of China POP-UP store service, has entered the peak development period. This paper takes China Estee Lauder POP-UP store as an example, based on the user experience of interactive marketing mode in Beauty POP-UP store under the new retailing model. The paper aims to establish a system interaction design process integrating online and offline to help enterprises complete the sustainable development of marketing services. To achieve this goal, this study uses questionnaires to investigate the key elements of user experience, customer journey map to determine the user pain points, and completes the design of the new system process. This process can provide designers with a new perspective through experimental verification, with high timeliness and practicability. It also promotes the collaborative optimisation and upgrading of physical retail and online retail and provides theoretical support and practical basis for other enterprises.

• Journal of Digital Contents Society
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• v.9 no.2
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• pp.177-185
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• 2008

It was a special phenomenon in the art of 20th century that the earnest engagement of spectators came up to the surface in the area of artwork-creation and art-experience which had been one-sided processes for a long time. Such a genre of Optical art or Kinetic art, had pulled out active engagements of audiences in enjoying diverse works, played the role of locomotive in the Interactive Art. Of course, many kind of art made an appearance on the channels of diverse media from that times. For example, many people came to enjoy taking part in such a genre as Happening formated the mode of face-to-face communication between the creator and the spectator. The appearance of the technology of digital media had a decisive influence on the area of the Interactive Art. From that time on, people have come to accept the reciprocity of the relations between artist and spectator naturally. This paper makes researches on some trends in the development of Interactive Arts by way of analyzing some representative Interactive Artworks typing the birth and growth of Interactive Art.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.4
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• pp.705-715
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• 2007

Recently, the interest on power quality has been hot issue because the equipments cause voltage disturbance and have become more sensitive to the voltage disturbance. Additionally, the reseach on power electronic equipments applying to the high power has been increased. This paper deals with Line-Interactive Dynamic Voltage Restorer(LIDVR) system using 7-Level H-Bridge inverter, which is one of the solutions to compensate the voltage disturbance and to increase the power of equipments. The LIDVR has the following advantages comparing to the DVR with the series injection transformer. It has the power factor near to unity under the condition of normal source voltage, can compensate the harmonic current of the load and the instant interruption, and has the fast response. First, the construction, the operation mode and algebraic modeling of LIDVR are reviewed. And then the voltage control algorithm is proposed to get the sinusoidal load voltage with constant amplitude. Finally, simulation and experiment results verify the proposed LIDVR system.

• Journal of applied mathematics & informatics
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• v.15 no.1_2
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• pp.511-525
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• 2004

we model communication and computer systems that process interactive and several and several types of background jobs. The scheduling policy in use is to share the processor among all interactive jobs and, at most, one background job of each type at a time according to the process sharing discipline. Background jobs of each type are served on a first-come-first-served basis. Such scheduling policy is called Processor Sharing with Background jobs (PSBJ). In fact, the PSBJ policy is commonly used on many communication and computer systems that allow interactive usage of the systems and process certain jobs in a background mode. In this paper, the stability conditions for the PSBJ policy are given and proved. Since an exact analysis of the policy seems to be very difficult, an approximate analytic model is proposed to obtain the average job sojourn times. The model requires the solution of a set of nonlinear equations, for which an iterative algorithm is given and its convergence is proved. Our results reveal that the model provides excellent estimates of average sojourn times for both interactive and background jobs with a few percent of errors in most of the cases considered.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.1
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• pp.81-88
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• 2007

In this paper, a new single-phase utility-interactive inverter system for residential power generation with fuel cell is proposed. The proposed inverter system is not only capable of working in both stand-alone and grid-connected mode, but also ensures smooth and automatic transfer between the two modes of operation. The proposed control method has little steady-state error and good transient response characteristic. Also, the control method can be implemented using low-cost, fixed point DSP since it has simpler structure, smaller amount of calculation, and smaller number of sensors. The controller for the proposed utility-interactive inverter system is described, and the validity is verified through simulation and experiment.

• Smart Structures and Systems
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• v.13 no.5
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• pp.731-753
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• 2014

In this study, an indirect approach is developed for assessing the state of a bridge on the basis of mode shapes estimated by the responses of passing vehicles. Two types of damages, i.e., immobilization of a support and decrease in beam stiffness at the center, are evaluated with varying degrees of road roughness and measurement noise. The assessment theory's feasibility is verified through numerical simulations of interactive vibration between a two-dimensional beam and passing vehicles modeled simply as sprung mass. It is determined that the damage state can be recognized by the estimated mode shapes when the beam incurs severe damage, such as immobilization of rotational support, and the responses contain no noise. However, the developed theory has low robustness against noise. Therefore, numerous measurements are needed for damage identification when the measurement is contaminated with noise.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.63-68
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• 2002

In a utility interactive photovoltaic generation system, a PWM inverter is used for the connection between the photovoltaic arrays and the utility. The do current becomes pulsated when the conventional inverter system operates in the continuous current mode and dc current pulsation causes the distortion of the ac current waveform. To reduce pulsation of dc input current, This paper presents a Buck-Boost PWM power inverter and its application for residential photovoltaic system. The PWM power inverter is realized by combining two sets of a high frequency Buck-Boost chopper and by making it operate in the discontinuous conduction mode. In this paper, we show the Buck-Boost PWM power inverter circuit, its equivalent circuit and basic differential equations and the power flow characteristics are clarified when the proposed Inverter is interconnected with the utility lines. In conclusion, the proposed inverter system provides a sinusoidal ac current for domestic loads and the utility line with unity power factor