• Annual Conference of KIPS
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• 2007.05a
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• pp.435-438
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• 2007

국내에서 디지털 방송 상용화에 성공하고 전송 모델 또한 다양화됨에 따라 사용자는 다양한 형식으로 다수의 방송 프로그램을 접할 수 있게 되었다. 이에 대한 효율적인 프로그램 관리를 위한 EPG(Electronic Program Guide) 서비스가 현재 제공되거나 개발 중이다. 지능형 개인화 EPG는 디지털 방송 스트림이 수신되는 환경에서 사용자와 방송 수신기의 지능적인 매개체로서 운영되며 본 연구는 기존 프로그램 정보에 대한 장르를 학습하고 새로운 프로그램 정보가 입력될 경우 올바르게 장르를 분류할 수 있도록 기계학습 기법이 사용되었다.

• The Journal of the Korea Contents Association
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• v.18 no.2
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• pp.147-157
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• 2018

Recently, with the advancement of network technologies, and the activation of IoT and social network services, many graph stream data have been generated. As the relationship between objects in the graph streams changes dynamically, studies have been conducting to detect or analyze the change of the graph. In this paper, we propose a scheme to incrementally detect frequent patterns by using frequent patterns information detected in previous sliding windows. The proposed scheme calculates values that represent whether the frequent patterns detected in previous sliding windows will be frequent in how many future silding windows. By using the values, the proposed scheme reduces the overall amount of computation by performing only necessary calculations in the next sliding window. In addition, only the patterns that are connected between the patterns are recognized as one pattern, so that only the more significant patterns are detected. We conduct various performance evaluations in order to show the superiority of the proposed scheme. The proposed scheme is faster than existing similar scheme when the number of duplicated data is large.

• Journal of KIISE:Databases
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• v.34 no.4
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• pp.343-356
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• 2007

Due to advances in position monitoring technologies such as global positioning systems and sensor networks, recent position information of moving objects has the form of streaming data which are updated continuously and rapidly. In this paper we propose an efficient trajectory maintenance method that stores the streaming position data of moving objects in the limited size of storage space and estimates past positions based on the stored data. For this, we first propose a new concept of incremental extraction of position information. The incremental extraction means that, whenever a new position is added into the system, we incrementally re-compute the new version of past position data maintained in the system using the current version of past position data and the newly added position. Next, based on the incremental extraction, we present an overall framework that stores position information and estimates past positions in the stream environment. We then propose two polynomial-based methods, line-based and curve-based methods, as the method of estimating the past positions on the framework. We also propose three incremental extraction methods: equi-width, slope-based, and recent-emphasis extraction methods. Experimental results show that the proposed incremental extraction provides the relatively high accuracy (error rate is less than 3%) even though we maintain only a little portion (only 0.1%) of past position information. In particular, the curve-based incremental extraction provides very low error rate of 1.5% even storing 0.1% of total position data. These results indicate that our incremental extraction methods provide an efficient framework for storing the position information of moving objects and estimating the past positions in the stream environment.

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1770-1780
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• 1997

Our problem is improvement of image quality because it is inevitable cell loss of image data when traffic congestion occurs. If cells are discarded indiscriminately in transmission of MPEG video data, it occurs severe degradation in quality of service(QOS). In this paper, to solve this problem, we propose two method. The first, we analyze the traffic characteristics of an MPEG encoder and generate high priority and low priority data stream. During network congestion, only the least low priority cells are dropped, and this ensures that the high priority cells are successfully transmitted, which, in turn, guarantees satisfactory QoS. In this case, the prioritization scheme for the encoder assigns components of the data stream to each priority level based on the value of a parameter ${\beta}$. The second, Number of high priority cells are increased when value of ${\beta}$ is large. It occurs the loss of high priority cell in the congestion. To prevent it, this paper is regulated to data stream rate as buffer occupancy with UPC controller. Therefore, encoder's bandwidth can be calculated renegotiation of the encoder and networks. In this paper, the encoder's bandwidth requirements are characterized by a usage parameter control (UPC) set consisting of peak rate, burstness, and sustained rate. An adaptive encoder rate control algorithm at the Networks Interface Card(NIC) computes the necessary UPC parameter to maintain the user specified quality of service. Simulation results are given for a rate-controlled VBR video encoder operating through an ATM network interface which supports dynamic UPC. These results show that dynamic bandwidth renegotiation of prioritized data stream could provided bandwidth saving and significant quality gains which guarantee high priority data stream.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2007.02a
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• pp.56-59
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• 2007

TPEG 메시지들은 바이트 기반 스트림 형태로 제작되고, 서비스 제공자의 데이터베이스에서부터 최종 사용자의 장비까지 교통 및 여행정보(TTI)관련 응용서비스 정보를 전달하기 위해 사용된다. 본 논문에서는 도로 교통정보에 대한 구간 및 지역별로 인터넷상에서 서비스 중인 지역 ITS정보에 대한 패킷을 분석하여 그 정보를 휴대용 단말기 상에서 구현하고자, TPEG 표준안 중 CTT 정보와 호환성을 갖도록 인코더를 제작하였고, 수신된 TPEG 메시지에 대한 디코더를 구현하였다. TPEG 디코더가 내장된 단말기 상에서 지역별 혼잡정보와, 구간별 소통정보 등을 지도정보와 매칭되어 실시간으로 표현되도록 구현하여, 현재 인터넷상에서 서비스 되고 있는 ITS 정보와 그 기능을 비교, 검토함으로서 네비게이션 단말기, PMP, PDA 등 휴대용 단말기에서 TPEG 기반 ITS 정보 제공서비스의 효용성을 입증하였다.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.10
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• pp.975-979
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• 2010

Existing quality adaptation schemes are useful for improving network stability in a congested network, but these schemes do not guarantee the quality of experience on video streaming due to the frequent variations in playback quality for a streaming service. In this paper, we propose a network-adaptive quality adaptation scheme to guarantee the quality of experience on SVC(Scalable Video Coding) video streaming. The proposed scheme estimates the available bandwidth by bandwidth measurement scheme using media characteristic, and then smoothly adjusts the quality level of SVC video stream according to the estimated bandwidth. Through the simulation, we prove that our scheme guarantees the quality of experience for video streaming by minimizing quality variation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.449-454
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• 2008

As demand for the application in multimedia networks is increasing rapidly, it is important to provide these services in Mobile Environments (ME). Obtaining to multimedia services which satisfy synchronization constraints in ME and improving the delay time and Quality of Service(QoS) between media streams to be presented, new specification model has to be proposed. In this paper we propose Mobile Synchronization Model(MSM) as a new specification model for describing efficiently the QoS and the delay time. Also, we propose the multimedia synchronization algorithm where is a dynamic synchronization method that minimizes the effects of adaptive transmission delay time. The proposed model has higher the guarantee of QoS such as the loss rate and the playout rate than it of the previous work.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2424-2430
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• 2012

The current Navigation System for the Visually Impaired Person has a short and limited communication distance and can't receive enough information from Visually Impaired Person to assist directly. In addition, because the path is dangerous and incomplete for the Visually Impaired Person, moving with White Stick is still inconvenient and dangerous. To solve this problem we implement communication that can send and receive video, voice, location information between the Visually Impaired Person's Smart Portable Navigation System Development and assistant's PC.

• Journal of the Korea Computer Industry Society
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• v.7 no.3
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• pp.217-226
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• 2006

Intensive studies have been made in the area of N-VOD server Multimedia files in the N-VOD sever are characterized with the large volume of data, the requirements of synchronization and real-time playback of streams. The basic goal of the study is to find an efficient mechanism to allow maximum number of users under the limited resources such as Buffer size and disk bandwidth. we propose a efficient VCR-LIKE operations and buffer, disk scheduling policy for multimedia services with management of VOD sever resources. Simulation results show that the rate of buffer usage and service time of proposed scheme are about 18% performance improved than that of traditional methods. This implies that our method can allow much more users for given resources.

• Journal of the Korea Computer Industry Society
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• v.6 no.3
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• pp.379-390
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• 2005

Intensive studies have been made in the area of VOD server Multimedia files in the VOD sever are characterized with the large volume of data, the requirements of synchronization and real-time playback of streams. The basic goal of the study is to find an efficient mechanism to allow maximum number of users under the limited resources such as Buffer size and disk bandwidth. we propose a efficient $pre\_fetching$ policy for multimedia services with dynamic monitoring and management of VOD sever resources. Simulation results show that the rate of buffer usage and service time of proposed scheme are about $28\%$ performance improved than that of traditional methods. This implies that our method can allow much more users for given resources.