• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2713-2719
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• 2012

According to increasing of various location-based services, distributed data stream processing techniques have been widely studied to provide high scalability and availability. In previous researches, in order to balance the load of distributed nodes, the geographic characteristics of spatial data stream are not considered. For this reason, distributed operations for adjacent spatial regions increases the overall system load. We propose a operation allocation scheme considering the characteristics of spatial operations to effectively processing spatial data stream in distributed computing environments. The proposed method presents the efficient share maximizing approach that preferentially distributes spatial operations sharing the common query regions to the same node in order to separate the adjacent spatial operations on overlapped regions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2852-2859
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• 1997

Video-On-Demand system provides electronic video rental services from remote video servers on a broadband communication networks. Most of proposed VOD systems are typically designed for one-to-one conncetion between a user and video server. Therefore, video server stream services to customers individually by allocating a dedicated transmission channel and a set of video server resources for each customer. However, it is inefficiency and wxpensive way when server support multiple users who access the same video stream with a dedicated video channel. Therefore, to achieve cost-effectiveness, batching have studied method that uses multicast communication to simultaneously service all users requesting the same video with a single video with a single video stream. However, the application of the multicast communication by batching detract from the VCR-like function and on-demand nature of the system. In this paepr, we propose a scheme that can support an interactive VCR for all user requesting the same video stream with batching. To reduce a server I/O and network bandwidth requirement, dynamic buffer is allocated to access node which has variable playout poit. Consequently, it makes possible interactive VCR operation as if customer uses true VOD system. Also, this scheme can just deliver a multicast stream without delay after an initial request or VCR action occurred. The policy can guarantee acceptable services to number of users at minimum cost.

• Journal of Ecology and Environment
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• v.48 no.1
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• pp.85-95
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• 2024

Background: In Korea, riparian zones and some floodplains have been converted into agricultural fields and urban areas. However, there are essential for maintaining biodiversity, as they are important ecological spaces. There are also very important spaces for humanity, as they perform various ecosystem services in a changing environment including climate change. Due to the importance of rivers, river restoration projects have been promoted for a long time, but their achievement has been insignificant. Development should be pursued by thoroughly evaluating the success of the restoration project. Ecological restoration is to accelerate succession, a process that a disturbed ecosystem recovers itself, with human assistance. Ecological restoration can be a test bed for testing ecological theories in the field. In this respect, ecological restoration should go beyond a 'simple landscaping exercise' and apply ecological models and theories in restoration practice. Results: The cross-section of the restored stream is far from natural rivers due to its steep slope and artificial material. The vegetation profiles of the restored streams did not reflect the flooding regime of the river. The species composition of the vegetation in the restored stream showed a significant difference from that of the reference stream, and was also different from that of an unrestored urban stream. Although species richness was high and the proportion of exotic species was low in the restored stream, the effect was offset by the high proportion of gardening and landscaping plants or obligate terrestrial plants. Conclusions: Based on both the morphological and ecological characteristics of the river, the restoration effect in the restored stream was evaluated to be very low. In order to solve the problems, a systematic adaptive management plan is urgently required. Furthermore, it is necessary to institutionalize the evaluation of restoration effects for the development of river restoration projects in the future.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.364-367
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• 2009

This paper presents a scheme that generates a caption file by extracting a Closed Caption stream from DTV signal. Note that Closed-Captioning service helps to bridge "digital divide" through extending broadcasting accessibility of a neglected class such as hearing-impaired person and foreigner. In Korea, DTV Closed Captioning standard was developed in June 2007, and Closed Captioning service should be supported by an enforcing law in all broadcasting services in 2008. In this paper, we describe the method of extracting a caption data from MPEG-2 Transport Stream of ATSC-based digital TV signal and generating a caption file (SAMI and SRT) using the extracted caption data and time information. Experimental results verify the feasibility of a generated caption file using a PC-based media player which is widely used in multimedia service.

• ETRI Journal
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• v.26 no.2
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• pp.112-121
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• 2004

Digital Multimedia Broadcasting (DMB) is an upcoming standard in Korea used to provide mobile multimedia broadcasting service based on the Eureka-147 Digital Audio Broadcasting (DAB) system. The current dominant multimedia coding standard, MPEG-4, is foreseen to play an important role in forthcoming DMB services. However, the current approaches for transporting MPEG-4 content over DMB networks are not optimized. To address this issue we propose a novel MPEG-4 stream multiplexer, called M4SMux, which provides better stream multiplexing and delivery over DMB networks. M4SMux features an MPEG-4 elementary-stream interleaving mechanism that reduces the multiplexing overhead and a multiplex configuration mechanism that utilizes M4SLinkTable for easy content access. In addition, we propose an error correction method which enhances transport efficiency.

• Journal of Information Processing Systems
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• v.17 no.2
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• pp.227-241
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• 2021

Object detection techniques based on deep learning such as YOLO have high detection performance and precision in a single channel video stream. In order to expand to multiple channel object detection in real-time, however, high-performance hardware is required. In this paper, we propose a novel back-end server framework, a real-time AI vision platform (RAVIP), which can extend the object detection function from single channel to simultaneous multi-channels, which can work well even in low-end server hardware. RAVIP assembles appropriate component modules from the RODEM (real-time object detection module) Base to create per-channel instances for each channel, enabling efficient parallelization of object detection instances on limited hardware resources through continuous monitoring with respect to resource utilization. Through practical experiments, RAVIP shows that it is possible to optimize CPU, GPU, and memory utilization while performing object detection service in a multi-channel situation. In addition, it has been proven that RAVIP can provide object detection services with 25 FPS for all 16 channels at the same time.

• 한국약용작물학회:학술대회논문집
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• 2011.09a
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• pp.402-403
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• 2011

• 한국약용작물학회:학술대회논문집
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• 2012.05a
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• pp.121-122
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• 2012

• The Journal of the Korea Contents Association
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• v.20 no.8
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• pp.42-53
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• 2020

With the development of social network services, graph structures have been utilized to represent relationships among objects in various applications. Recently, a demand of subgraph matching in real-time graph streams has been increased. Therefore, an efficient approximate Top-k subgraph matching scheme for low latency in real-time graph streams is required. In this paper, we propose an approximate Top-k subgraph matching scheme considering data reuse in graph stream environments. The proposed scheme utilizes the distributed stream processing platform, called Storm to handle a large amount of stream data. We also utilize an existing data reuse scheme to decrease stream processing costs. We propose a distance based summary indexing technique to generate Top-k subgraph matching results. The proposed summary indexing technique costs very low since it only stores distances among vertices that are selected in advance. Finally, we provide k subgraph matching results to users by performing an approximate Top-k matching on the summary indexing. In order to show the superiority of the proposed scheme, we conduct various performance evaluations in diverse real world datasets.

• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.35-44
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• 2009

The emerging notion of data stream has brought many new challenges to the research communities as a consequence of its conceptual difference with conventional concepts of just data. One typical example is data stream processing in sensor networks. The range of data processing considerations in a sensor network is very wide, from physical resource restrictions such as bandwidth, energy, and memory to the peculiarities of query processing including continuous and specific types of queries. In this paper, as one of the physical constraints in data stream processing, we consider the problem of limited memory and propose a new scheme for data stream reduction based on the Principal Component Analysis (PCA) technique. PCA can transform a number of (possibly) correlated variables into a (smaller) number of uncorrelated variables. We adapt PCA for the data stream of a sensor network assuming the cooperation of a query engine (or application) with a network base station. Our method exploits the spatio-temporal correlation among multiple measurements from different sensors. Finally, we present a new framework for data processing and describe a number of experiments under this framework. We compare our scheme with the wavelet transform and observe the effect of time stamps on the compression ratio. We report on some of the results.