• Proceedings of the Korea Multimedia Society Conference
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• 1998.04a
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• pp.323-327
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• 1998

컴퓨터와 통신망 기술의 발전으로 많은 언론 기관에서 전자신문 서비스를 제공하고 있다. 그러나 현재 서비스되는 전자신문은 텍스트 위주의 정적인 정보를 주고 서비스 하며, 사용자가 필요한 정보를 찾아 다니는 pull 기술을 기반으로 서비스한다. 그리고 사용자 맞춤 기능을 제공하기 못하므로, 불필요한 정보를 사용자에게 전송함으로써 시스템 자원을 낭비하는 단점을 가지고 있다. 본 논문에서는 멀티미디어 데이터를 지원하는 NOD(News On Demand)시스템에서 텍스트 데이터 뿐아니라 오디오/비디오 데이터를 push 하므로써 서버의 load를 분배시키고 사용자에게 실시간성을 제공하는 NOD 분배 서버를 설계하고 프로토타입을 구현하였다. 특히 본 논문에서는 대용량 데이터인 오디오/비디오 데이터를 사용자 시스템으로 Push할 때, 사용자 시스템의 디스크 공간상태 등을 고려하여 실시간성을 유지할 수 있는 적정 Push 량을 시뮬레이션을 통해 측정하였다.

• Proceedings of the KOSOMBE Conference
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• v.1985 no.06
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• pp.1-4
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• 1985

본 논문에서는 모빌 로봇에 확장하기 위한 시도로서 대기조건에 따른 오차를 보상한 맹인 안내용 mobile Robot의 ultrasonic ranging system을 설계하였다. 본 system에서는 MCS-80 microcomputer를 이용하여 주위환경에 대한 다량의 정보를 실시간으로 처리하였고, 다각적인 정보획득을 위하여 stepping motor로서 sensor를 회전시켰으며, 대기조건에 따른 오차보상을 위하여 기준거리 비교방법을 사용하였고, offset과 근접장애물로 인한 오인식을 방지하기 위하여 받아들여진 data를 선정할 수 있도록 A/D converter를 사용하였다. 또한 맹인 아내를 위한 audio tone generator에 대하여 연구하였으며, 그밖에 외부 system과의 I/O interface 등 이 system에 대한 hardware와 software에 관하여 논하였다. 본 System에서 거리측정 오차는 약 1cm 정도이고 측정가능거리는 $0.2{\sim}6m$이다.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.7
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• pp.302-307
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• 2002

Digital watermarking is the technique, which embeds an invisible signal including signal including owner identification and copy control information into multimedia data such as audio, video, and images for copyright protection. A new MPEG watermark embedding algorithm using complex block effect based on the Human Visual System(HVS) is introduced in this paper. In this algorithm, $8{\times}8$ dark blocks are selected, and the watermark is embedded in the DC component of the discrete cosine transform(DCT) by using quantization and modulus calculation. This algorithm uses a blind watermark retrieval technique, which detects the embedded watermark without using the original image. The experimental results show that the proposed watermark technique is robust against MPEG coding, bitrate changes, and various GOP(Group of Picture) changes.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.428-430
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• 2006

This paper proposes a new means of performance optimization for multimedia algorithm utilizing the Microscopic DVS (Dynamic Voltage Scaling). The Microscopic DVS technique controls the operating frequency and the supply voltage levels dynamically according to the processing requirement for each frame of multimedia data. The huffman decoding algorithm of MPEG-2 AAC audio decoder is optimized to maximize the power saving efficiency of Microscopic DVS technique. The experimental results show the reduction of computational complexity by more than 30% and the reduction of power consumption by more than 17% compared with those of the conventionally fast method.

• Journal of The Korean Association For Science Education
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• v.32 no.3
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• pp.502-523
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• 2012

The purpose of this study is to explore the relationship between selected components of conceptual ecology that are reflected in high school science students' statements, when answering questions. This study follows from a position that there is reason to believe that, in the process of answering questions, many aspects of conceptual ecology are likely to play a role. Data were gathered through six audio-taped interviews, the science teacher's profiles of each student, the students' personal journals, their assignments, and their examinations and participation in class. Kay and KY were selected as the focus of this study because theirs were both dramatic as well as representative cases. As the findings suggest, learning styles differ according to distinctions within individuals' conceptual ecologies. Thus the way in which a person learns science varies according to the construction of her/his conceptual ecology. This suggests that different forms of pedagogy may be effective with different types of learners. This also suggests that science educators may have a role in assisting students to develop into constructed, rather than received, learners.

• Information and Communications Magazine
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• v.17 no.3
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• pp.123-136
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• 2000

데이터(Data), 영상(Video) 그리고 음성(Audio)을 특정 사용자 그룹에게만 전송하는 데이터 전송기술인 멀티캐스트(Multicast)는 효과적인 그룹 접근 제어의 결려와 단일 유니캐스트 통신보다 많은 통신 링크 때문에, 부당한 공격자에게 많은 공격 기회를 제공하고 있다. 이것은 그룹의 수신자에게만 영향을 미치는 것이 아니라 잠재적으로 대부분의 네트워크에 연결된 사용자에게 영향을 미친다. 특히 참가자의 가입과 탈퇴 시에 신분위장, 재전송, 부인공격에 노출되어있기 때문에 이러한 부단한 공격 위협에 대한 보안대책이 필요하다. 본 논문에서는 안전한 멀티캐스트 트래픽 전송을 위한 보안 메커니즘 설계를 위한 기반 기술로서 멀티캐스트에서 보안의 필요성과 멀티캐스트에서 고려해야할 보안 서비스를 분석하고 단일 송신자와 다중 그룹에서 구성될 수 있는 보안 구조 및 보안 구성요소를 연구하였다.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.12
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• pp.544-546
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• 2006

This paper proposes a new means of performance optimization for multimedia algorithm utilizing the Microscopic DVS (Dynamic Voltage Scaling). The Microscopic DVS technique controls the operating frequency and the supply voltage levels dynamically according to the processing requirement for each frame of multimedia data. The huffman decoding algorithm of MPEG-2 AAC audio decoder is optimized to maximize the power saving efficiency of Microscopic DVS technique. The experimental results show the reduction of computational complexity by more than 30% and the reduction of power consumption by more than 17% compared with those of the conventionally fast method.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.669-670
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• 2008

In this paper, we present a real-time system to detect abnormal events on gas pipes, based on the signals which are observed through the audio sensors attached on them. First, features are extracted from these signals so that they are robust to noise and invariant to the distance between a sensor and a spot at which an abnormal event like an attack on the gas pipes occurs. Then, a classifier is constructed to detect abnormal events using neural networks. It is a combination of two neural network models, a Gaussian mixture model and a multi-layer perceptron, for the reduction of miss and false alarms. The former works for miss alarm prevention and the latter for false alarm prevention. The experimental result with real data from the actual gas system shows that the proposed system is effective in detecting the dangerous events in real-time with an accuracy of 92.9%.

• ETRI Journal
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• v.31 no.1
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• pp.65-67
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• 2009

We introduce an advanced terrestrial digital multimedia broadcasting (AT-DMB) system that overcomes the limitation of data transmission rates of T-DMB by doubling it with the same frequency bandwidth. In this letter, we propose an efficient algorithm which generates a scalable transport stream in AT-DMB by multiplexing certain types of elementary streams encoded using scalable video coding and an MPEG-surround audio coder for high-quality multimedia services.

• Proceedings of the KSPS conference
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• 2007.05a
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• pp.281-284
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• 2007

This experimental study aims to find out the correlation between semantic predictability and pitch-accent realization. For the experiment, we classified the predictability into three degrees: unpredictable, implicitly predictable, and explicitly predictable. And then each degree divided into to two subcatergories: one is adverbs/adverbial phrases of time or place and the other one is not time or place adverbs/adverbial phrases. The materials used in the experiment were 9 sentences for the each subcategory. One male and one female English native speakers participated in this experiment. Their reading speeches were recorded on Digital Audio Tape. Their speech data were analyzed by using Pitchworks program. The results of this experiment show pitch accented ratio is somewhat in inverse proportion to the degree of predictability.