• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.975-978
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• 2004

본 논문에서 우리는 가상현실 시스템의 구축에 있어서, 사용자의 직접 상호작용 (direct interaction)을 기본으로 하는 근신 공간(near-body space) 작업에서 사용자의 존재감 (Presence) 향상과 작업 성능 향상을 위하여, 사용자와 공간적 및 감각적으로 일치된 가상 인체 모델의 구현을 중심으로 현재의 기술 현황 및 연구 개발 방향에 대하여 기술한다. 이상적인 가상현실 시스템을 구현하기 위해서 고려되어야 할 요소를 멀티모달 상호작용과 실감 일치형 인터페이스 개발 방법론의 관점에서 보면, 사용자가 접하는 가상 공간의 시각적 모델(visual perception)과 자기 동작 감각적(proprioceptive) 모델의 일치가 중요하다. 그러므로, 시각적으로 사용자의 움직임과 일치된 자신의 신체가 가시화 되어야 하고, 자연스러운 근신 공간 직접 상호작용을 지원하기 위해서는 사실적인 햅틱 피드백 요소가 중요하며, 공간적 정보를 표현 함에 있어서 동기화 된 사실적 청각 피드백 요소의 지원이 중요하다. 앞의 주요 3 가지 감각 인터페이스 방법(sensory channel, modality)는 현재의 불완전한 인터페이스 기술의 한계를 고려하여 상호 보완적인 관계로 응용 환경에 최적화된 적용 방법이 연구되어야 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.307-312
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• 2000

Asynchronous transfer mode(ATM) is flexible to support the various multimedia communication services such as data, voice, and image by applying asynchronous time-sharing and statistical multiplexing techniques to the existing data communication. ATM service is categorized to CBR, VBR, UBR, and ABR according to characteristics of the traffic and a required service qualities. Among them, ABR service guarantees a minimal bandwidth and can transmit cells at a maximum transmission rate within the available bandwidth. To minimize the cell losses in transmission and switching, a feedback information in ATM network is used to control the traffic. In this paper, predictive control algorithms are proposed for the feedback information. When the feedback information takes a long propagation delay to the backward nodes, ATM switch can experience a congestion situation from the queue length increases, and a high queue length fluctuations in time. The control algorithms proposed in this paper provides predictive control model using slop changes of the queue length function and previous data of the queue lengths. Simulation shows the effectiveness result of the proposed control algorithms.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.6
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• pp.698-703
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• 2003

This paper presents analog secure communication system about safe speech transmission using chaotic signals. We applied various conditions that happen in actuality communication environment modifying chaotic synchronization and chaotic communication schemes and analyzed restoration performance of speech signal to computer simulation. In transmitter, we made the chaotic masking signal which is added voice signal to chaotic signal using PC(Pecora ＆ Carroll) and SFB(self-feedback) control techniques and transmitted encryption signal to noisy communication channel And in order to calculate the degree of restoration performance, we proposed the definition of analog average power of recovered error signals in receiver chaotic system. The simulation results show that feedback control techniques can certify that restoration performance is superior to quantitative data than PC method about masking degree, susceptibility of parameters and channel noise. We experimentally computed the table of relation of parameter fluxion to restoration error rate which is applied the encryption key values to the chaotic secure communication.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.11a
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• pp.59-65
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• 2002

보다 현실감 있는 가상환경을 제공하기 위하여 시각정보 외에 힘의 정보를 사용자에게 제공할 필요가 있으며, 이러한 힘 반영은 햅틱장치에 의해서 수행된다. 일반적으로 영상 제시기에 의한 영상정보는 낮은 갱신율을 갖는 반면에, 햅틱장치는 상대적으로 높은 갱신율로 인간에게 힘정보를 제공하게 되므로, 이들 정보 간의 동기화가 중요하다. 본 논문에서는 가시모델의 원형을 일반화시켜서 햅틱장치에 전달하고, 영상 제시기의 갱신율과는 상관 없이 햅틱장치 내에서 임의의 구속공간을 만들어서 힘피드백을 수행하는 방법에 대해서 논의하고자 한다.

• Journal of Digital Convergence
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• v.17 no.11
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• pp.435-440
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• 2019

Recently, many musical instrument mobile apps have been released targeting normal people who can't play musical instrument at all. The reason of developing video system based on step sequencer are as follows; first, users can freely play the musical instruments; second, induce multiple users to play; and third, develop and suggest new step sequencer fused with the video. To resolve issue in video synchronization caused by sync issues when operating multiple step sequencers, the Pocket Operator of Teenage Engineering was used to realize multiply-connected step sequencer and also, the ultimate video system was developed through Mira-Web for multiple participation. In addition, it's required to make the Pocket Operator as software and receive various feedbacks to continue and complement study in order to develop the better video system.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.3
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• pp.316-322
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• 2014

A movie recommendation system is proposed to learn a preference model of a viewer by using multimodal features of a video content and their evoked implicit responses of the viewer in synchronized manner. In this system, facial expression, body posture, and physiological signals are measured to estimate the affective states of the viewer, in accordance with the stimuli consisting of low-level and affective features from video, audio, and text streams. Experimental results show that it is possible to predict arousal response, which is measured by electrodermal activity, of a viewer from auditory and text features in a video stimuli, for estimating interestingness on the video.

• Journal of The Korean Association of Information Education
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• v.4 no.1
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• pp.40-56
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• 2000

Web based learning has been used for many educational systems by aid of the development of internet technique. The true process of education includes not only learning contents but also learning process and the evaluation. So far, Web-based evaluation mainly consists of the evaluation of the learning products or the evaluation of the cognitive domain. But, there is lack of the appropriate feedback for learning effects. In this paper, we design and implement an evaluation system for Web-based instruction. In our system, the learners are evaluated during the process of Web-based learning. Our system provides learner-centered instruction for students with instant feedback. The questions made up by teachers are stored in the database and can be searched by a keyword, grade, semester or unit. The evaluation system can also provide the feedback to right or wrong answer for each question. Our system provides the learners with instant feedback after solving the questions and also can improve the quality of learning process using the Web.

• The Journal of Korean Association of Computer Education
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• v.9 no.2
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• pp.69-78
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• 2006

Educational evaluation is not the work to rank learners hierarchically, but the thing to increase the educational effectiveness by solving a learner's problem and improving the education process from the proper evaluation. The conventional evaluation systems have measured a learner's recognition level by dichotomy. Although they support the evaluation depending on a learner's academic ability and supply the feedback for wrong selection, it is insufficient to take out study-motive and give the establishment for a guidance point of learning. In this paper, we propose the web-based individual adaptive testing system in considering partial score for a learner. Our system are effective to estimate the ability of learner by considering partial score in detail and offer an feedback study from the self-diagnosis function for a learning results.

• Journal of Internet Computing and Services
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• v.1 no.2
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• pp.29-37
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• 2000

Asynchronous transfer mode is flexible to support multimedia communication services using asynchronous time-sharing and statistical multimedia techniques to the existing data communication area, ATM ABR service controls network traffic using feedback information on the network congestion situation in order to guarantee the demanded service qualities and the available cell rates, In this paper we apply the control method using queue length prediction to the formation of feedback information for more efficient ABR traffic control. If backward node receive the longer delayed feedback information on the impending congestion, the switch can be already congested from the uncontrolled arriving traffic and the fluctuation of queue length can be inefficiently high in the continuing time intervals, The feedback control method proposed in this paper predicts the queue length in the switch using the slope of queue length prediction function and queue length changes in time-series, The predicted congestion information is backward to the node, NLMS and neural network are used as the predictive control functions, and they are compared from performance on the queue length prediction. Simulation results show the efficiency of the proposed method compared to the feedback control method without the prediction, Therefore, we conclude that the efficient congestion and stability of the queue length controls are possible using the prediction scheme that can resolve the problems caused from the longer delays of the feedback information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8A
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• pp.859-867
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• 2004

To provide high-quality media streaming service over the best-effort Internet, a streaming methodology is required to response to the dynamic fluctuation of underlying networks. In this paper, we implement the MPEG-4 streaming system with adaptive transport based on priorities of media packets. The implemented system is composed of the common MPEG-4 streaming components such as elementary stream provider, sync and DMIF layer, and adaptive transport module including data prioritization and FEC control. More specifically, the prioritized sync layer packets (based on object level) are delivered to the transport module and then are encoded by an adaptive FEC encoder to help reliable transport. The FEC combination is dynamically adjusted by the feedback information from the receiver. In addition, low priority packets are selectively dropped to meet the limitation of available bandwidth. The experimental results over the emulation-based testbed show that the Proposed system can mitigate the impact of network fluctuation and thus improve the quality of streaming.