• Educational Technology International
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• 제10권2호
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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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• 한국태양에너지학회 2008년도 춘계학술발표대회 논문집
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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.

• 한국전자통신학회논문지
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• 제7권2호
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• pp.227-234
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• 2012

컴퓨터와 인터넷의 발달은 사회 전 분야에 걸쳐 많은 변화를 가져왔다. 교육 시장도 이에 적극적으로 부응하여 원격교육, 사이버교육, 가상강의, e-Learning 등의 이름으로 제안되어지며 다양한 서비스를 제공하고 있다. 이를 위한 시스템들이 다양하게 제공되면서 컴퓨터를 이용하여 이루어지는 교육과 평가가 활발히 이루어지고 있다. 그러나 많은 시스템들이 제한적 기능을 제공하고 있는 것이 사실이다. 이에 본 논문에서는 학습자들의 교육 이해 수준 정도를 실시간으로 피드백(Feedback)함으로써 교수자가 맞춤식교육을 진행할 수 있는 CBT(Computer Based Training/Test)방식의 쌍방향 자율모드 기반 교육 환경을 제공하는 RTE(Real Training Environment) 시스템을 제안한다. 이 시스템을 활용하여 학습자의 능력에 맞는 맞춤식 교육 환경을 제공하고 학습자들의 학습동기를 극대화시킬 수 있을 것으로 생각된다.

• 디지털융복합연구
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• 제19권6호
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• pp.343-353
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• 2021

중국의 뷰티 팝업숍 서비스는 이미 전성기발전시기에 들어섰다. 본 연구는 중국 에스티로더 팝업샵을 예를 들어 새 소매모델하에서의 뷰티샵 인터랙티브 마케팅방식에서의 사용자 체험을 기초로 일종의 온라인과 오프라인을 융합하는 시스템 인터랙티브 디자인 과정을 세우고 기업이 마케팅 서비스의 지속가능한 발전을 이루도록 돕는다. 이 목적을 달성하기 위해 본 연구에서는 설문조사와 인터뷰 조사로 사용자 체험의 핵심 요소를 조사하고 고객 여정 지도를 이용해 사용자의 통증점 (접촉점)을 확인하고 새 시스템 흐름의 디자인을 완성한다. 실험검증을 통해 이 과정은 디자이너들에게 새로운 시각을 제공한다. 비교적 높은 시효성과 실용성을 가지고 있고 또한 오프라인 소매와 온라인소매의 협동 최적화와 업그레이드를 촉진하여 기타 기업에 팝업스토어 써비스의 이론지지와 실천적의거를 제공해준다.

• 디지털콘텐츠학회 논문지
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• 제9권2호
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• pp.177-185
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• 2008

향수자 일방의 관조적인 관람을 전제로 하는 작품 창작의 주류 속에서 관람자 참여의 문제가 본격적으로 대두된 것은 20세기 예술에서였다. 수동적 관람자로부터 능동적 참여를 끌어낸 옵아트나 키네틱아트 등은 향후 전개될 인터랙티브 아트의 견인차 역할을 했다. 작가와 관람자의 상호대면을 포맷화하는 '해프닝' 장르 등의 작업들도 TV나 아날로그 매체를 통한 관람자와의 소통 양식들을 적극적으로 끌어들이게 된다. 이후 컴퓨터를 이용한 디지털 매체가 본격적으로 등장하면서 관람자와 인터랙티브 아트의 상호소통을 통한 작품의 창작은 결정적 전기를 맞게 된다. 본 논문은 예술 사조사에서 인터랙티브아트의 생성과 전개의 맥락을 전형화하는 대표적 작품들의 사례 분석을 통해 인터랙티브 아트의 발전적 흐름을 고찰하고자 한다.

• 전기학회논문지
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• 제56권4호
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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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• 제15권1_2호
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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.

• 전력전자학회논문지
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• 제12권1호
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• pp.81-88
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• 2007

본 논문에서는 연료전지를 이용한 가정용 발전 시스템의 계통 연계를 위한 새로운 단상 인버터 시스템을 제안한다. 제안한 인버터는 계통연계 운전과 독립 운전이 모두 가능하고 두 운전사이의 모드전환이 자동으로 이루어지며 전환시 최소의 과도상태를 갖는다. 제안한 제어방식은 정상상태 오차가 거의 없고 양호한 과도상태 응답특성을 가진다. 또한 연산량과 센서수가 적고 구조가 간단하여 저가격의 고정소수점 DSP로도 구현이 가능한 특징이 있다. 제안한 계통연계형 인버터의 제어기에 관하여 기술하고 모의실험 및 실험에 의하여 그 타당성을 입증한다.

• Smart Structures and Systems
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• 제13권5호
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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.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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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