• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.2
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• pp.75-82
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• 2004

The changes of sea bottom configuration, which may cause the coastal disasters, have been considered as social problems. It is obvious that the beach deformation is attributable to the sediment transport associated with erosion and acceration. The prediction method and countermeasures for them, however, are not on the level of satisfaction, which indicates that efforts should be made on developing them. In this study, it is found at the groin constructed in Sangju beach on e purpose of beach protection did the aversive function. The reason for this was judged that they accelerated the speed of erosion by increasing the velocity wave-induced current rather than brought storage effect of sediment. Authors found that the storage sediment estimation model by Sonu and Beek(1971) is a useful model at the Sangju beach with the use of topographical survey data from July, 1987 to March, 2003.

• Journal of Korea Multimedia Society
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• v.10 no.6
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• pp.726-736
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• 2007

In this paper, real-time image scanning system using linescan cameras is designed. The system is specially designed to diagnose and analyse the conditions of tunnels such as crack widths through the captured images. The system consists of two major parts, the image acquisition system and the image merging system. To save scanned image data into storage media in real-time, the image acquisition system has been designed with two different control and management modules. The control modules are in charge of controlling the hardware device and the management modules handle system resources so that the scanned images are safely saved to the magnetic storage devices. The system can be mounted to various kinds of vehicles. After taking images, the image merging system generates extended images by combining saved images. Several tests are conducted in laboratory as well as in the field. In the laboratory simulation, both systems are tested several times and upgraded. In the field-testing, the image acquisition system is mounted to a specially designed vehicle and images of the interior surface of the tunnel are captured. The system is successfully tested in a real tunnel with a vehicle at the speed of 20 km/h. The captured images of the tunnel condition including cracks are vivid enough for an expert to diagnose the state of the tunnel using images instead of seeing through his/her eyes.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.9
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• pp.445-458
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• 2007

This article presents a novel infrastructure for large-memory database processing using commodity hardware with operating system support. We exploit inexpensive PCs and a high-speed network capable of Remote Direct Memory Access (RDMA) operations to build a new memory hierarchy between fast volatile memory and slow disk storage. The new memory hierarchy guarantees a reasonable response time, and its storage size enables us to run large-memory database systems with little performance degradation. The proposed architecture has two main components: (1) a remote memory system inside the Linux kernel to manage other computers' memory pages efficiently and (2) a remote memory pager responsible for manipulating remote read/write operations on remote memory pages. We insist that the proposed architecture is practical enough to support the rigorous demands of commercial in-memory database systems by demonstrating the performance of publicly available main-memory databases (e.g., MySQL) on our prototyped system. The experimental results show very interesting results from the TPC-C benchmark.

• Journal of KIISE:Databases
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• v.30 no.3
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• pp.225-236
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• 2003

MOLAP systems store data in a multidimensional away called a 'cube' and access them using way indexes. When a cube is placed into disk, it can be Partitioned into a set of chunks of the same side length. Such a cube storage scheme is called the chunk-based MOLAP cube storage scheme. It gives data clustering effect so that all the dimensions are guaranteed to get a fair chance in terms of the query processing speed. In order to achieve high space utilization, sparse chunks are further compressed. Due to data compression, the relative position of chunks cannot be obtained in constant time without using indexes. In this paper, we propose a bitmap index for chunk-based MOLAP cubes. The index can be constructed along with the corresponding cube generation. The relative position of chunks is retained in the index so that chunk retrieval can be done in constant time. We placed in an index block as many chunks as possible so that the number of index searches is minimized for OLAP operations such as range queries. We showed the proposed index is efficient by comparing it with multidimensional indexes such as UB-tree and grid file in terms of time and space.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.293-300
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• 2016

Traditional databases exploit a record-based model, where the attributes of a record are placed contiguously in a slow hard disk to achieve high performance. On the other hand, for read-intensive data analysis systems, the column-based compressed database has become a proper model because of its superior read performance. Currently, flash memory SSD is largely recognized as the preferred storage media for high-speed analysis systems. This paper introduces a compressed column-storage model and proposes a new index and its data management scheme for a high-capacity data warehouse system. The proposed index management scheme is based on the asymmetric index duplication and achieves superior search performance using the master index and compact index, particularly for large read-mostly databases. In addition, the data management scheme contributes to the read performance and high reliability by compressing the related columns and replicating them in two mirrored SSD. Based on the results of the performance evaluation under the high workload conditions, the data management scheme outperforms the traditional scheme in terms of the search throughput and response time.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.33-40
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• 2005

Recently So far Many low-cost mobile machinery have been produced. Those are being used for study and business. But those are some weak Points which are small-capacity storage and quite low-speed system. If we use general database programs or key-searching algorithm, It could decrease in performance of system. To solve those Problems, we applied CBDS(Compact Binary Digital Search) trie to mobile environment. As a result we could accomplish our goal which are quick searching and low-capacity indexing. We compared with some Java classes such as TreeSet to evaluation. As a result, the velocity of searching was a little slow than B-tree based TreeSet. But the storage space have been decreased by 29 percent. So I think that it would be practical use.

• Journal of Technologic Dentistry
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• v.33 no.3
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• pp.193-202
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• 2011

Purpose: The aim of this study was to evaluate the effect of pre-treatment of core and hydrothermal treatment on the bond strength and flexural strength of ceramic veneered zirconia. Methods: 3Y-TZP specimens(KaVo Zr, $25mm{\times}3mm{\times}1mm$)were prepared by five pre-treatment methods and divided into seven groups including control two groups, subsequently the specimens veneered with the E-MAX ceram according to manufacturer's information(total specimen thickness 1.5mm). Two groups from ceramic-zirconia specimens(n=105, n=15 per group)were assigned into two experimental fatigue conditions, namely storage in an autoclave at $134^{\circ}C$ for 5h, thermo-cycling(3,000cycles, between 5 and $55^{\circ}C$, dwell time 45s, transfer time 2s). A flexural strength test was performed in a universal testing machine(crosshead speed: 0.5mm/min). Data were statistically analyzed using one-way ANOVA and Tukey's test(${\alpha}$=0.05). Results: The ceramic-zirconia bond strength value for liner application group(LLW, $27.3{\pm}3.8$) were significantly lower than those of the pre-treatment groups($30.72{\pm}5.3$). The ceramic-zirconia bond strength and zirconia flexural strength was not affected by thermo-cycling(p>0.05), whereas it was affected by storage in an autoclave at $134^{\circ}C$ for 5h(p<0.05). Conclusion: The results indicated that the ceramic-zirconia bond strength and zirconia flexural strength was affected by low temperature degradation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.4
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• pp.34-40
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• 2010

This paper proposes an efficient CABAC encoder to reduce syntax element storage in H.264/AVC entropy coding. In the proposed architecture, all blocks are designed in dedicated hardware, so it performs fast processing without programmable processors. Context modeler of CABAC encoder requires the neighbor block data. However it requires impractically huge memory size if the neighbor block data is directly stored without proper processing. Therefore, this paper proposes an effective method of storing the neighbor block data to decrease memory size. The proposed CABAC encoder has 35,463 gates in 0.18um standard cell library. It operates at maximum speed of 180MHz and its throughput is about 1 cycle per input symbol.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.1
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• pp.30-40
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• 2010

The hard disk is one of the most frequently used storage in IPTV sep-top box. It has large storage capacity and provides fast I/O speed compared to its price whereas it causes high power consumption due to mechanical characteristics of spindle motor. In order to play streaming data in the set-top box, spindle motor of hard disk keeps active mode and it causes high power consumption. In this paper, We propose an offset-buffering and multi-mode spin-down method to reduce power consumption for streaming data playback. The offset-buffering inspects the user's viewing pattern and performs buffering based on the analysis of viewing pattern. So, it can maintain the status of spindle motor as idle mode for long time. Besides, it can reduce power consumption by spinning down according to offset-buffer size. The experimental result shows that proposed offset-buffering and multi mode spin-down method is about 28.3% and 12.5% lower than the full-Buffering method in terms of the power consumption and spin-down frequency, respectively.

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1257-1265
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• 2006

As XML is increasingly used, the need of researches which are related with XML in various fields is also augmented. Many XML document management systems have been actively developed especially for the storage, processing and retrieval of XML documents. The BitCube is a three dimensional bitmap index system that could be manipulated efficiently and improves the performance of document retrieval. However, the site of index is increase rapidly, when a new bit is added to the axis. This problem is caused by its three dimensional memory structure with document, path and word. We suggest a path combining strategy of XML documents in this paper to solve the problem of BitCube that mentioned above. To reduce the size of index, our approach combines sibling nodes that has same ancestor paths, and transforms word axis into value axis. The method reduces the size of index, when the system com poses the three dimensional bitmap index. It also improves the speed of retrieving, and takes efficiency in storage space.