• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.4
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• pp.1-11
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• 2001

This study was carried out to analyze the characteristics of forest environmental and stream morphological factors by using the quantification theory(I) for evaluation of the watershed stability. Present annual mean sediment yield of erosion control dams were investigated in 167 sites of erosion control dam constructed during 1986 to 1999 in Gyeongbuk. The results obtained from this study were summarized as follows; According to the coefficients of partial correlation, each factor affecting to sediment was shown in order of gravel contents, number of first streams order, number of total streams, length of total streams, forest type, length of main stream, parent rock, stand age, soil texture, stream order, slope gradient, soil depth and aspect. Descriptions of class I were as follow; Igneous rock of parent rock, hardwood stands of forest type, less than 20 year of stand age, less than 30cm of soil depth, sandy clay loam of soil texture, more than 41% of gravel contents, south~east of aspect, 2,501~3,500m of length of main stream, 21~25 of number of total streams, 5,501~10,000m of length of total streams, 3 or more than 4 of stream order, more than 16 of number of first stream orders and more than $31^{\circ}$ of slope gradient. Descriptions of class II were as follow; Metamorphic rock of parent rock, coniferous stands of forest type, more than 25 year of stand age, 31~40cm of soil depth, silt loam of soil texture, 11~20% of gravel contents, north~west of aspect, 2,501~3,500m of length of main stream, 16~20 of number of total streams, 3,501~5,500m of length of total streams, 3 of stream order, 11~15 of number of first stream orders and more than $31^{\circ}$ of slope gradient. Descriptions of class III were as follow; Sedimentary rock of parent rock, mixed stands of forest type, more than 25 year of stand age, more than 51cm of soil depth, silty clay loam of soil texture, less than 10% of gravel contents, south~west of aspect, less than 500m of length of main stream, less than 5 of number of total streams, less than 1,000m of length of total streams, less than 1 of stream order, less than 2 of number of first stream orders and less than $25^{\circ}$ of slope gradient. The prediction method of suitable site for erosion control dam divided into class I, II, and III for the convenience of use. The score of class I evaluated as a very unstable area was more than 8.4494. A score of class II was 8.4493 to 6.0452, it was evaluated as a moderate stable area, and class III was less than 6.0541, it was evaluated as a very stable area.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.8
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• pp.34-40
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• 1992

This paper shows a new relational formula of multiplexing gain versus variable input bit rates useful for designing Nx1 ATM(Asynchronous Transfer Mode) multiplexer which mixes several asynchronous bit streams with different transmission rates. The relation between multiplexing gain and input bit stream speeds is derived from the occupied mean lenght(the width per unit time) of cells and the occupation probability of the number of cells at an arbitrary instant when the rates of the periodic cell strams change randomly. And the relation between multiplexing gain and variable bit rates from different number of input bit streams is analyzed accordingly. Under the condition of unlimited multiplexing speed, the more number of input bit streams increases, the bigger the multiplexing gain becomes. While for the case which restricts the multiplexing speed to a limited value, the multiplexing gain becomes smaller contrarily as the number of input bit streams continues too invrease beyond a boundary value. It is shown that for designing an ATM multiplexer according to the latter case, the combination of input bit streams should be determined such as its total bit rate is lower thean, but most apprpaximate to, the multiplexed output speed. Also the general formula evaluating the most significant parameters which should be needed to design the multiplexer is derived.

• Journal of Communications and Networks
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• v.5 no.3
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• pp.258-265
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• 2003

Transmission of continuous media streams has been a challenging problem of multimedia service. Lots of works have been done trying to figure out the best solution for this problem, and some works presented the optimal solution for transmitting the stored video using smoothing schemes applied to each individual stream. But those smoothing schemes considered only one stream, not the whole streams being serviced, to apply themselves, which could only achieve local optimum not the global optimum. Most of all, they did not exploit statistical multiplexing gain that can be obtained before smoothing. In this paper, we propose a new smoothing scheme that deals with not an individual stream but the whole streams being serviced simultaneously to achieve the optimal network bandwidth utilization and maximize the number of streams that can be serviced simultaneously. We formally proved that the proposed scheme not only provides deterministic QoS for each client but also maximizes number of clients that can be serviced simultaneously and hence achieves maximum utilization of transmission bandwidth.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.7
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• pp.211-218
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• 1994

Stochastic computation employs random pulse streams to represent numbers. In this paper, we study a new method to implement the number system which uses the ratio of the numbers of ones and zeros in the pulse streams. In this number system. if P is the probability that a pulse is one in a pulse stream then the number X represented by the pulse stream is defined as P/(1-P). We propose circuits to implement the basic operations such as addition multiplication and sigmoid function with this number system and examine the error characteristics of such operations in stochastic computation. We also propose a neuron model and derive a learning algorithm based on backpropagation for the 3-layered feedforward neural networks. We apply this learning algorithm to a digit recognition problem. To analyze the results, we discuss the errors due to the variance of the random pulse streams and the quantization noise of finite length register.

• Environmental Engineering Research
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• v.15 no.2
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• pp.111-115
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• 2010

To study the relationship between the concentrations of nitrogen in mountain streams, and anthropologic and natural factors, the water chemistry of the mountain streams in the entire Hyogo Prefecture, Japan, were investigated. A thousand mountain streams were investigated between 1998 and 2001. The concentrations of nitrate nitrogen ranged from 2.92 to 0.1 mg/L, with an arithmetic mean value of 0.45 mg/L. A number of streams showing more than 1.0 mg/L of nitrate nitrogen accounted for 8% of the mountain streams investigated. These results indicated that the concentrations of nitrate nitrogen in the mountain streams were low in the entire Hyogo Prefecture. In general, the mountain stream water in Hyogo Prefecture appears to not have been affected by wet and dry deposition originating from anthropologic sources in mountain streams and Japan. On the other hand, sites with more than 0.8 mg/L nitrate nitrogen were distributed over the entire Hyogo Prefecture, which were classified into five groups. Each group showed unique geographical, geological and anthropological characteristics. No common characteristic among five groups were discover. These results suggest that the cause of high concentrations of nitrogen in mountain streams is not from a uniform set of conditions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.4
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• pp.1841-1865
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• 2017

This paper proposes a new interference mitigation scheme for device-to-device (D2D) communications underlaying a cellular network. The object of the proposed scheme is to determine the number of data streams, a precoding matrix, and a decoding matrix of D2D networks so as to maximize the system capacity given the number of data streams of a cellular network while satisfying the constraint of the inter-system interference from D2D networks to the cellular network. Unlike existing interference mitigation schemes based on the interference alignment technique, the proposed scheme operates properly regardless of the number of data streams of a cellular network and moreover it does not require changing the precoding and decoding matrices of a cellular network. The simulation results demonstrate that the proposed scheme significantly increases the system capacity by mitigating the intra- and inter-system interference.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.9
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• pp.1646-1653
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• 2008

In this paper, we propose multicarrier CDMA system using the concept of the modulation level-controlled system in order to make the system robust to the frequency selectivity and to provide a maximum data rate maintaining an acceptable transmission quality over various channel environments. This system selects higher data rate when the channel experiences the low delay spread and slow fading. On the other hand, when the fading changes very fast and the delay spread is very long, the system selects lower data rate. In both cases, the system controls the number of serial-to-parallel converted streams and the number of fed streams. This system has the fixed number of sub-carriers. So the product of tile number of serial-to-parallel converted streams and the number of fed streams is always kept constant. With the same data fed at different sub-carriers, the frequency diversity is achieved. And a RAKE receiver also is utilized to achieve path (time) diversity.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.406-409
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• 2008

Clustering data streams has an importance over many applications like sensor networks. Existing hierarchical methods follow a semi fuzzy clustering that yields duplicate clusters. In order to solve the problems, we propose an extended online divisive agglomerative clustering on data streams. It builds a tree-like top-down hierarchy of clusters that evolves with data streams using geometric time frame for snapshots. It is an enhancement of the Online Divisive Agglomerative Clustering (ODAC) with a pruning strategy to avoid duplicate clusters. Our main features are providing update time and memory space which is independent of the number of examples on data streams. It can be utilized for clustering sensor data and network monitoring as well as web click streams.

• Journal of KIISE:Databases
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• v.36 no.3
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• pp.180-188
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• 2009

Recently, the needs for an efficient and secure access control method of dynamic XML data in a ubiquitous data streams environment have become an active research area. In this paper, we proposed an improved role-based prime number labeling scheme for an efficient and secure access control labeling method in dynamic XML data streams. And we point out the limitations of existing access control and labeling schemes for XML data assuming that documents are frequently updated. The improved labeling method where labels are encoded ancestor-descendant and sibling relationships between nodes but need not to be regenerated when the document is updated. Our improved role-based prime number labeling scheme supports an infinite number of updates and guarantees the arbitrary nodes insertion at arbitrary position of the XML tree without label collisions. Also we implemented an efficient access control using a role-based prime number labeling. Finally, we have shown that our approach is an efficient and secure through experiments.

• Journal of information and communication convergence engineering
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• v.14 no.2
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• pp.84-88
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• 2016

As good example of potential application-specific requirement, (m,k)-firm real-time streams have been recently introduced to deliver multimedia data efficiently in wireless sensor networks. In addition to stream model, communication protocols to meet specific (m,k)-firm real-time streams have been newly developed or extended from existing protocols. However, since the existing schemes for an (m,k)-firm stream have been proposed under typical flat architecture, the scalability problem remains unsolved when the number of real-time flows increases in the networks. To solve this problem, in this paper, we propose a new clustering scheme for an (m,k)-firm stream. The two different clustering algorithms are performed according to either the (m,k)-firm requirement or the deadline. Simulation results are presented to demonstrate the suitability of the proposed scheme under hierarchical architecture by showing that its performance is acceptable irrespective of the increase in the number of flows.