• International Journal of Computer Science & Network Security
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• v.21 no.4
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• pp.209-213
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• 2021

Data mining is the application of specific algorithms for extracting patterns from data and KDD is the automated or convenient extraction of patterns representing knowledge implicitly stored or captured in large databases, data warehouses, the Web, other massive information repositories or data streams. Data mining can be used for decision making in educational system. But educational institution does not use any knowledge discovery process approach on these data; this knowledge can be used to increase the quality of education. The problem was happening in the educational management system, but to make education system more flexible and discover knowledge from it huge data, we will use data mining techniques to solve problem.

• Journal of Information Processing Systems
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• v.6 no.1
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• pp.67-78
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• 2010

In this study, a clustering algorithm that uses DCT transformed data is presented. The algorithm is a grid density-based clustering algorithm that can identify clusters of arbitrary shape. Streaming data are transformed and reconstructed as needed for clustering. Experimental results show that DCT is able to approximate a data distribution efficiently using only a small number of coefficients and preserve the clusters well. The grid based clustering algorithm works well with DCT transformed data, demonstrating the viability of DCT for data stream clustering applications.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2601-2610
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• 2013

The main limiting factors of Precise Point Positioning(PPP) accuracy are errors in broadcast satellite orbits, clock errors, and the others, which are receiver-dependent errors(ionospheric, tropospheric refraction, multipath, and tides, etc.). Therefore, to facilitate high precision PPP, precise orbits/clocks corrections, the receiver-dependent errors corrections have to apply to multi frequency GNSS measurements for an ionosphere free combination and integer ambiguity resolution in real-time. Currently, there are many Analysis Centers, which offer the precise corrections stream computed in real-time using the global or regional GNSS tracking network. The goles of this research considered performances of the real-time static PPP with using RTCM corrections from NTRIP casters. For this, the corrections streams of Analysis Centers received via NTRIP does apply to GNSS data of check points individually, as well as jointly, in accordance with various session lengths. After that, have compared the PPP results from the corrections streams with each other, and with Standard Point Positioning(SPP) results.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.11
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• pp.581-588
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• 2007

In Digital Right Management, symmetric cipher is used for content encryption to reduce encryption cost, AES, advanced encryption standard is usually used to multimedia encryption under desktop environment because of its reasonable security level and computation cost. But mobile handheld device often uses slow speed processor and operates under battery-powered environment. Therefore it requires low computation cost and low energy consumption. This paper proposes new stream cipher scheme which combines pseudo random number generator(PRNG) and dynamically generated permutations. Proposed scheme activates PRNG and generates original key streams. Then it generates extended key streams by applying permutation to original sequence. These extended key streams are XORed with plaintext and generate ciphertext. Proposed scheme reduces the usage of PRNG. Therefore this scheme is fast and consumes less energy in comparison with normal stream cipher. Especially, this scheme shows great speed up (almost 2 times) than normal stream cipher scheme in random access.

• Journal of Environmental Impact Assessment
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• v.20 no.2
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• pp.207-215
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• 2011

In order to establish fundamental data for stream restoration and environmental flow, we investigated physical habitat conditions of Korean chub (Zacco koreanus) in the typical streams of Han River. Field monitoring including fish sampling was conducted from September 2008 to April 2010. A total number of fish caught in the 8 sites was 3,421 representing 8 families 31 species, and 17 species (54.8%) including Korean shinner (Coreoleuciscus splendidus) and Z. koreanus were Korean endemic species during the study period. The most frequently found species in number was pale chub (Z. platypus, 25.7%) followed by Z. koreanus (22.8%) and Microphysogobio longidorsalis (16.8%). Numbers of Z. Koreanus ranged from 8 to 10 cm of total length were the highest in size distribution of their population in all sites. They were widely found in ranges of flow velocity (0.2~0.9 m/sec, 89.6%), water depth (0.3~0.9 m, 91.6%), and different types of substrates except for silt, and they tended to prefer run (58.1%) and riffle (33.7%) with cobble bed (47.0%) microhabitat. Most of upper streams in Korea consist of riffles and runs that are repeatedly followed by another one. However, stream channelization and leveling have caused reduction of habitat diversity. Therefore, it is necessary to make an effort on stream rehabilitation with evaluation of physical habitat condition by indicator species in order to maintain biodiversity and perform ecological restoration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6B
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• pp.615-625
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• 2008

In this study, classification of streams was conducted for Ji Stream, a tributary to the Geum River and Yo Stream, a tributary to the Seomjin River, and in addition, channel evolution model to the same streams was applied. The classification approaches suggested by Rosgen and Korea Institute of Construction Technology (KICT) were conducted. The channel evolution model suggested by Schumm et al. (1984) was applied. Based on the application results of Rosgen approach, Ji Stream and Yo stream show the characteristics of mountainous stream with pebbles. The application results of channel evolution model indicated that the current condition of Ji Stream and Yo Stream is a state of equilibrium, balancing the sediment supply and sediment transport capacity. The results of this study can be used as a fundamental data for water control project, river restoration and appropriate channel planning.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.2
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• pp.164-168
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• 2002

In this article, we present the novel approach of avoiding temporal insufficiency of data blocks, jitter, which occurs due to the commencement of new session. We propose to make the sufficient amount of data blocks available on memory such that the ongoing session can survive the cycle extension. This technique is called ″pre-buffering″. We examine two different approaches in pre-buffering: (i) loads all required data blocks prior to starting playback and (ii) incrementally accumulates the data blocks in each cycle. We develop an elaborate model to determine the appropriate amount of data blocks necessary to survive the cycle extension and to compute startup latency involved in loading these data blocks. The simulation result shows that limiting the disk bandwidth utilization to 60% can greatly improve the startup latency as well as the buffer requirement for individual streams.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.49-52
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• 2000

The Multi-Code CDMA systems that are proposed as an effective transmission methodology in the IMT-2000 systems allow higher rate services under the IS-95 CDMA infrastructure. The Multi-Code CDMA systems convert the higher rate data into the lower rate by serial to parallel operation and spread the converted data streams by the multiple walsh codes, and its mobile receiver needs multiple walsh generators and data correlators to demodulate simultaneously multiple walsh code channels. Therefore, the number of data correlators is increased as the number of traffic channels increases. In this paper, we proposed the new structure of the data correlators using walsh overlay coding, the shared accumulator, and FWHT(Fast Walsh Hadamard Transform) algorithm for reducing the bottle-neck effect resulting the increase of the number of data correlators.

• Korean Journal of Environmental Agriculture
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• v.27 no.2
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• pp.105-110
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• 2008

The main purpose of this work is the development of water quality level model using the data such as DO, EC, BOD, $COD_{Cr},\;NH_3-N,\;NO_3-N,\;PO_4-P$, T-N, T-P, and SS in 88 agricultural streams of the Han river watersheds. To grant water quality level for each parameters, it divided into 20% respectively in the order of water quality level. On the basis of the lowest water quality level, water quality of streams was assigned. As the result, number of stream corresponding to Level Ⅰ was 0, Level II was 1 stream, Level III was 3 streams, Level IV was 22 streams, and Level V was 62 streams. By standardized canonical discriminant function coefficient, $NO_3-N$ was the highest in 0.427 at the discriminant power. According to discriminant function for water quality level, it was equal to $-4.648+3.246{\times}[NO_3-N],\;-5.084+3.456{\times}[NO_3-N],\;-4.298+3.067{\times}[NO_3-N],\;and\;-7.369+4.396{\times}[NO_3-N]$ from Level II to Level V, respectively. As a result of test at real data of the Han river watersheds in 2007, the suitability of water quality level model was high to 88.4%.

• Agricultural and Biosystems Engineering
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• v.4 no.2
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• pp.50-57
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• 2003

This study was conducted to develop software which provides automatic site-specific field data acquisition, data processing, data mapping and management for precision agriculture. The developed software supports acquisition and processing of both digital and analog data streams. The architecture was object-oriented and each component in the architecture was developed as a separate class. In precision agriculture research, the laborious task of manual ground-truth data collection will be avoided using the developed software. In addition, gathering high-density data eliminates the need for interpolation of values for un-sampled areas. This software shows good potential for expansion and compatibility for variable-rate-application (VRA). The FIM (Field Information Management) computer program provides the user with an easy-to-follow process for field information management for precision agriculture.