• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.9 no.1
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• pp.179-187
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• 2019

With the recent development of small computing devices, IoT sensor network can be widely deployed and is now readily available with sensing, calculation and communi-cation functions at low cost. Sensor data management is a major component of the Internet of Things environment. The huge volume of data produced and transmitted from sensing devices can provide a lot of useful information but is often considered the next big data for businesses. New column-wise compression technology is mounted to the large data server because of its superior space efficiency. Since sensor nodes have narrow bandwidth and fault-prone wireless channels, sensor-based storage systems are subject to incomplete data services. In this study, we will bring forth a short overview through providing an analysis on IoT sensor networks, and will propose a new storage management scheme for IoT data. Our management scheme is based on RAID storage model using column-wise segmentation and compression to improve space efficiency without sacrificing I/O performance. We conclude that proposed storage control scheme outperforms the previous RAID control by computer performance simulation.

• The KIPS Transactions:PartD
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• v.10D no.3
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• pp.459-470
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• 2003

It is required to research on high-dimensional index structures for efficiently retrieving high-dimensional data because an attribute vector in data warehousing and a feature vector in multimedia database have a characteristic of high-dimensional data. For this, many high-dimensional index structures have been proposed, but they have so called ‘dimensional curse’ problem that retrieval performance is extremely decreased as the dimensionality is increased. To solve the problem, the cell-based filtering (CBF) scheme has been proposed. But the CBF scheme show a linear decreasing on performance as the dimensionality. To cope with the problem, it is necessary to make use of parallel processing techniques. In this paper, we propose a parallel CBF scheme which uses a horizontally-partitioned technique as declustering. In order to maximize the retrieval performance of the proposed parallel CBF scheme, we construct our parallel CBF scheme under a SN (Shared Nothing) cluster architecture. In addition, we present a data insertion algorithm, a rage query processing one, and a k-NN query processing one which are suitable for the SN cluster architecture. Finally, we show that our parallel CBF scheme achieves better retrieval performance in proportion to the number of servers in the SN cluster architecture, compared with the conventional CBF scheme.

• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.463-476
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• 2001

To support the mobility, mobile computers are generally equipped with lower capability than desktop PCs or workstations in terms of the size of a display, the processing power of CPU and so on. This may give a rise to limitation in mobile computers of supporting multimedia services such as World Wide Web which users would otherwise fully enjoy in desktop PCs. Approaches to reducing the limitations are distillating original multimedia data or converting them to text. Conventional proxy servers for mobile computer simply send distillated image files with the fixed size regardless of the display size of a target mobile computer. Since the cached data is kept separately for each user, they cannot be shared among users with the same display configuration and thus the proxy server could be overloaded. In this paper, we first classify various mobile computers based on their display capability in terms of display sizes and colors. We propose an enhanced proxy server called Class-based proxy that provides a mobile computer with distillated image files in proportion to its class display capacity. The proposed proxy server allows a mobile computer user to have a homepage view similar to that in PC or Workstation. Mobile computers with the same class share the cached image files, which are distillated appropriately for that class. This helps the proxy server to get higher cache hit ratio with improved efficiency and scalability.

• Journal of Korea Multimedia Society
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• v.14 no.9
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• pp.1165-1174
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• 2011

In data broadcasting systems, servers continuously disseminate data items through broadcast channels, and mobile client only needs to wait for the data of interest to present on a broadcast channel. However, because broadcast channels are shared by a large set of data items, the expected delay of receiving a desired data item may increase. This paper explores the issue of designing proper data allocation on multiple broadcast channels to minimize the average expected delay time of all data items, and proposes a new data allocation scheme named two level bin-packing(TLBP). This paper first introduces the theoretical lower-bound of the average expected delay, and determines the bin capacity based on this value. TLBP partitions all data items into a number of groups using bin-packing algorithm and allocates each group of data items on an individual channel. By employing bin-packing algorithm in two step, TLBP can reflect a variation of access probabilities among data items allocated on the same channel to the broadcast schedule, and thus enhance the performance. Simulation is performed to compare the performance of TLBP with three existing approaches. The simulation results show that TLBP outperforms others in terms of the average expected delay time at a reasonable execution overhead.

• The KIPS Transactions:PartA
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• v.9A no.2
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• pp.137-146
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• 2002

In VOD server, in order to guarantee playback of continuous media, such as video, without hiccups for multiusers, the server has to manage its buffer sophisticatedly by prefeching a part of the data into the buffer As the continuous media data buffered by one user can be used again by the others, the number of disk accesses is reduced and then the latency time far the users is also reduced. In this paper, we propose a new buffer management technique for continuous media in VOD server. Our basic algorithm partitions the buffer into groups and then a group of buffer which has the lowest utilization is chosen and partitioned again for a new user. The basic algorithm is extended for supporting multiple streams and clip data and for providing VCR functions. Our proposed technique is able to increase in the number of concurrent users as increasing the utilization of the buffer and to minimize the average waiting time for multiuser accesses as the bandwidth of storage is slowly reached to the limit. In the simulation study for comparing the performance of our technique with that of the existing techniques, we show that the average waiting time is reduced mere than 50% and the number of concurrent users increases by 1 ∼5% as compared with those of the exiting techniques.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.6
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• pp.602-613
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• 2001

Recently, the computing has developing in distributed object computing environment for supporting a programming paradigm of distributed application requiring interoperability between heterogeneous clients and servers. It involves the complex networking and the object-oriented technologies for various multimedia application service. In this paper, we construct the real-time object group platform for solving the difficulties of managements of distributed objects and the real-time constraints by requiring for real-time service supporting of applications in distributed computing environment. The existing researches are being tried to only improving the performance of systems by using real-time CORBA itself, or modifying the part of CORBA compliance. Hence, we design a new model of real-time object group platform that can support the real-time requirement without modifying the ORB. The structure of our real-time object group analyzed and defined the requirement about object management and real-time application service sides. And the role of the components of real-time object group is divided into 2 classes for reducing the side effect of interoperability between management and service. Also, we considered how to transparently express the parameters of real-time properties for clients and developers of server's service objects. If the expression of real-time parameters is transparent, then the developer can easily extend the real-time parameters simply and flexibly. Therefore, in this paper we defined the role of components of platform and described functions of each component and designed and then implemented the real-time object group platform. Finally, we showed the execution procedures of implemented our platform for verifying the functionality.