• KIPS Transactions on Computer and Communication Systems
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• v.1 no.3
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• pp.219-228
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• 2012

As the wireless Internet become more widely accessible, variety of Internet services can be used without limitation of location. However, existing mobility management methods such as MIP and PMIP of IETF requires the load of heavy protocol stack on the mobile nodes or the addition of components such as LMA and MAG. In this paper, we proposed the location management technique in the PMIPv6 and Fast Handover technique. according to the moving pattern of the node, the location management technique proposed in order to adjust the paging area dynamically. The Fast Handover technique applied MIH technology and it reduced the handover signal processing time between heterogeneous network. The location management cost in the environment which the node moves in order to evaluate this and handover delay time was calculate. The proposal technique was efficiently more evaluated than PMIPv6 with the smallest 29% and maximum 83%.

• Annals of Clinical Neurophysiology
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• v.2 no.1
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• pp.8-12
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• 2000

Purpose : The rapid development and wide popularity of Digital EEG(DEEG) is due to its convenience, accuracy and applicability for quantitative analysis. These advantages of DEEG make one hesitate to use analog EEG(AEEG). To assess the advantage of DEEG system utilizing AEEG(DAEEG) over conventional AEEG and the clinical applicability, a DAEEG system was developed and applied to animal model Methods : Sprague-Dawley rat as status epilepticus model were used for collecting the EEG data. After four epidural electrodes were inserted and connected to 8-channel analog EEG(Nihon-Kohden, Japan), continous. EEG monitoring via computer screen was done from two rats simultaneously. EEG signals through analog amplifier and filters were digitized at digital signal processor and stored in Windows-based pentium personal computer. Digital data were sampled at a rate of 200 Hz and 12 bit of resolution. Acquisition software was able to carry out 'real-time view, sensitivity control and event marking' during continuous EEG monitoring. Digital data were stored on hard disk and hacked-up on CD-ROM for off-line review. Review system consisted of off-line review, saving and printing out interesting segment and annotation function. Results: This DAEEG system could utilize most major functions of DEEG sufficiently while making a use of an AEEG. It was easy to monitor continuously compared to Conventional AEEG and to control sensitivity during ictal period. Marking the event such as a clinical seizure or drug injection was less favorable than AEEG due to slowed processing speed of digital processor and central processing unit. Reviewing EEG data was convenient, but paging speed was slow. Storage and management of data was handy and economical. Conclusion : Relatively simple digital EEG system utilizing AEEG can be set-up at n laboratory level. It may be possible to make an application for clinical purposes.

• The Journal of the Korea Contents Association
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• v.3 no.2
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• pp.65-72
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• 2003

In this paper, the new scheme using a Combined Cache(CC) that combing the Paging and Routing Cache(PRC) and an alternative handoff method according to the type of data transmission for achieving the efficient realtime communication. The PRC and quasi-soft handoff method reduce the path duplication. But they increase the network traffic load because of the handoff state packet of Mobile Host(MH). Moreover the use the same handoff method without differentiating the type of transmission data. Those problems are solved by operating U with a semi-soft handoff method for realtime data transmission and with a hard handoff method for non-realtime data transmission. As a result or simulation a better performance is obtained because of the reduction of the number of control packet in case that the number of cells are below 20. And the packet arrival time and loss of packet decreased significantly for realtime data transmission.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.469-478
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• 2001

In the virtual memory system, page replacement policy exerts a great influence on the performance of demand paging. There are LRU(Least Recently Used) and LFU (Least Frequently Used) as the typical replacement policies. The LRU policy performs effectively in many cases and adapts well to the changing workloads compared to other policies. It however cannot distinguish well between frequently and infrequently referenced pages. The LFU policy requires that the page with the smallest reference count be replaced. Though it considers all the references in the past, it cannot discriminate between references that occurred far back in the past and the more recent ones. Thus, it cannot adapt well to the changing workload. In this paper, we first analyze memory reference patterns of eight applications. The patterns show that the recently referenced pages or the frequently referenced pages are accessed continuously as the case may be. So it is rather hard to optimize page replacement scheme by using just one of the LRU or LFU policy. This paper makes an attempt to combine the advantages of the two policies and proposes a new page replacement policy. In the proposed policy, paging list is divided into two lists (LRU and LFU lists). By keeping the two lists in recency and reference frequency order respectively, we try to restrain the highly referenced pages in the past from being replaced by the LRU policy. Results from trace-driven simulations show that there exists points on the spectrum at which the proposed policy performs better than the previously known policies for the workloads we considered. Especially, we can see that our policy outperforms the existing ones in such applications that have reference patterns of re-accessing the frequently referenced pages in the past after some time.

• Journal of Digital Contents Society
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• v.13 no.1
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• pp.119-127
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• 2012

In this study, it was witnessed that a variety of tests are implemented in a type of convergence of multimedia such as photos, sounds, and videos as well as letters and drawings, components of existing traditional comics as comics are digitalized and are converted to various devices. Therefore, we studied the concept of multimedia comics as a basis of this study by judging that new barometer to comics lies in convergence with such multimedia. After recognizing components of multimedia comics which are currently emerging, we categorized them into three types depending on how to use these elements. First, convergence type webtoon has a very similar format with existing vertical scrolling webtoon and has characteristics that background & effects sounds are added to emphasize the features of webtoon, or photos or videos are inserted in part, and there is no function to control these elements; Second, motion comic, a medium format between comic and animation has a characteristic that sound, video, paging are auto-played like watching animation but it keeps the format of comics within one frame; Third, interactive comic has a characteristic that effects sound, motion, and story are made by active participation of viewers. As a result of analyzing comics which having above multimedia characteristics, its implications are as followings: First, multimedia elements should be used depending on genre, age, and media; Second, high level of control technology considering the features of comic-viewers is needed. In other words, in continuously evolving media environments, comic contents being proper to targets and use purposes of viewers should be developed. For this, multimedia elements of comics should be used in order that comic-viewers can have active & interactive communication with contents.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1289-1300
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• 2011

In recent computer systems with high-performance, users execute programs needing large memory and programs intensively accessing files simultaneously. Such a large memory requirement makes virtual memory systems access swap spaces in disk, and intensive file accesses require file systems to access file system partitions in disk. Executing the two kinds of programs at once incurs large disk seeks between swap spaces and file system partitions frequently. To solve the problem, this paper proposes a new scheme called SAF to create several swap spaces in a file system partition, where pages to be paged out are stored. When a page is paged out, the scheme stores the page to one of the swap spaces close to a disk location where the most recently accessed file is located. The chosen swap space in the file system partition is closer to the disk location than the traditional swap space, so that our scheme can reduce the large disk seek time spent to move to the traditional swap space in paging out a page. The experiment of our scheme implemented in FreeBSD 6.2 shows that SAF reduces the execution time of several benchmarks over FreeBSD ranging from 14% to 42%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2784-2790
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• 2015

The column-oriented database storage is a very advanced model for large-volume data transactions because of its superior I/O performance. Traditional data storages exploit row-oriented storage where the attributes of a record are placed contiguously in hard disk for fast write operations. However, for search-mostly data warehouse systems, column-oriented storage has become a more proper model because of its superior read performance. Recently, solid state drive using flash memory is largely recognized as the preferred storage media for high-speed data analysis systems. In this research, we propose a new transaction recovery scheme for a column-oriented database environment which is based on a flash media file system. We improved traditional shadow paging schemes by reusing old data pages which are supposed to be invalidated in the course of writing a new data page in the flash file system environment. In order to reuse these data pages, we exploit reused shadow list structure in our column-oriented shadow recovery(CoSR) scheme. CoSR scheme minimizes the additional storage overhead for keeping shadow pages and minimizes the I/O performance degradation caused by column data compression of traditional recovery schemes. Based on the results of the performance evaluation, we conclude that CoSR outperforms the traditional schemes by 17%.