• The KIPS Transactions:PartD
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• v.13D no.7 s.110
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• pp.889-900
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• 2006

Even though sensor networks are different in user requests and data characteristics depending on each application area, the existing researches on stream data transmission problem focus on the performance improvement of their methods rather than considering the original characteristic of stream data. In this paper, we introduce a hierarchical or distributed sensor network architecture and data model, and then evaluate the multivariate data reduction methods suitable for user requirements and data features so as to apply reduction methods alternatively. To assess the relative performance of the proposed multivariate data reduction methods, we used the conventional techniques, such as Wavelet, HCL(Hierarchical Clustering), Sampling and SVD (Singular Value Decomposition) as well as the experimental data sets, such as multivariate time series, synthetic data and robot execution failure data. The experimental results shows that SVD and Sampling method are superior to Wavelet and HCL ia respect to the relative error ratio and execution time. Especially, since relative error ratio of each data reduction method is different according to data characteristic, it shows a good performance using the selective data reduction method for the experimental data set. The findings reported in this paper can serve as a useful guideline for sensor network application design and construction including multivariate stream data.

• Journal of Korea Water Resources Association
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• v.54 no.12
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• pp.1215-1222
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• 2021

In this study, a study on how to use a fire hydrant as a heat wave reduction facility through hydraulic analysis of the water supply pipe network was conducted. Assuming that the fire hydrant installation point is open for heat wave reduction, the water pressure at each point was derived. And the reduction rate of the temperature according to the hydrant watering was compared with the watering area according to the operation of the watering truck. The watering area according to the opening of the fire hydrant was calculated by deriving the pressure value at the node where the fire hydrant was installed through hydraulic analysis of the water pipe network, and then using the watering radius relational expression according to the pressure value. As a result of applying the proposed methodology to two real city areas, the temperature reduction effect of the watering method by a fire hydrant can be derived lower than the watering method by a watering truck according to the difference in the absolute watering area. However, unlike a watering truck, a fire hydrant does not have a relative restriction on the amount of water supply and is expected to allows continuous divided spraying of the same area.

• Journal of Korean Society of Transportation
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• v.29 no.2
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• pp.91-100
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• 2011

Hub network design for freight transportation is a decision process that determines hub locations together with freight transportation routes among shippers so as to ultimately minimize total logistics cost. This study presents the optimal location of hubs by strict hub network design policy with single allocation, which overcomes the limitation of Kim et al. (2008) that does not allow direct transportation among shippers. The greedy-interchange algorithm is employed for hub location decision process, and EMME/2 is adopted for the route searching process. Application of the processes to the nationwide highway network shows that the best hub locations in order are Seoul metropolitan, GyeongNam, Chung-nam, Jeon-Nam, Gyeong-Buk, Chung-Buk, and the locations are concentrated on the Seoul-Busan corridor. The strict hubnetwork design policy with single allocation increases the transportation distance but decreases the transportation cost by passing through the hubs instead of direct transportation. The reduction in total transportation cost can be achieved as the number of hubs increases, but the amount of the reduction gradually decreases because the cost reduction from the decrease in detour transportation distance between non-hubs and hubs becomes less than the discount reduction from dispersion of inter-hubs transportation volumes.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.2923-2936
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• 2024

Modern risk management philosophy emphasizes the invulnerability of human beings to cope with all kinds of emergencies. The Nuclear Accidents Emergency Response Organization (NAERO) of Nuclear Power Plant (NPP) is the primary body responsible for nuclear accidents emergency response. The invulnerability of the organization to disturbance or attack from internal and external sources is crucial in the completion of its response missions, reduction of severity of accidents, and assurance of public and environmental safety. This paper focused on the NAERO of a certain NPP in China, and applied the complex network theory to construct the network model of the organization. The topological characteristics of the network were analyzed. Four importance evaluation indexes of network nodes including Degree Centrality (DC), Betweeness Centrality (BC), Closeness Centrality (CC) and Eigenvector Centrality (EC), along with Pearson coefficient correlation among the indexes were calculated and analyzed. Size of the Largest Connected Component (LCC) and Network Efficiency were used as measures regarding the invulnerability of the network. Simulation experiments were conducted to assess the invulnerability of network against various attack strategies. These experiments were conducted both in the absence of node protection measures and under protection measures with different node protection rates. This study evaluated the invulnerability of the NAERO network, and provided significant decision-making basis for the enhancement of the network's invulnerability.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.3
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• pp.1-10
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• 2006

In this paper we deal with a cell planning issue arisen in a CDMA based multicast network. In a CDMA based wireless network, a terminal can significantly reduce the bit error rate via the cohesion of data streams from multiple base stations. In this case, multiple base stations have to be operated according to a common time line. The cells whose base stations are operated as such are called soft-combined cells. Therefore, a terminal can take advantage of error rate reduction, if the terminal is in a soft-combined cell and at least one neighboring cell is also soft-combined. However, as soft-combining operation gives heavy burden to the network controller, the limited number of cells can be soft-combined. Our problem us to find a limited number of soft-combined cells such that the benefit of the soft-combining operation is maximized.

• Structural Engineering and Mechanics
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• v.26 no.4
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• pp.377-392
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• 2007

A discrete sliding mode control (SMC) method based on hybrid model of neural network and nominal model is proposed to reduce the vibration of flexible structures, which is a robust active controller developed by using a sliding manifold approach. Since the thick boundary layer will reduce the virtue of SMC, the multilayer feed-forward neural network is adopted to model the uncertainty part. The neural network is trained by Levenberg-Marquardt backpropagation. The design objective of the sliding mode surface is based on the quadratic optimal cost function. In course of running, the input signal of SMC come from the hybrid model of the nominal model and the neural network. The simulation shows that the proposed control scheme is very effective for large uncertainty systems.

• Proceedings of the KWS Conference
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• 2000.04a
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• pp.251-255
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• 2000

Recently, the improvement of computer capacities and artificial intelligence ware caused to employ for prediction of residual stresses and strength evaluation. There are a lot of researches regarding the measurement and prediction of residual stresses for weldment using a neural network in the advanced countries, but in our country, a neural network as a technical part, has only been used on the possibilities of employment for welding area. Furthermore, the relationship between residual stress and process parameters using a neural network was wholly lacking. Therefore development of a new technical method for the optimized process parameters on the reduction of residual stress and applyment of real-time production line should be developed. The objectives of this paper is to measure the residual stress of butt welded specimen using strain gage sectioning method and to apply them to a neural network for prediction of residual stresses on a given process parameter. Also, the assessment of the developed system using a neural network was carried out

• Proceedings of the Safety Management and Science Conference
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• 2002.05a
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• pp.121-127
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• 2002

In this paper, we propose traffic management support and evaluate the performance through simulation. We suggest traffic management routing protocol that can guarantee reliance according to not only reduction of the Network traffic congestion but also distribution of the network load that prevents data transmission. For performance evaluation, we analyzed the average data reception rate and network load, considering the node mobility. We found that in the mobile Ad Hoc networks, the traffic management service increased the average data reception rate and reduced the network traffic congestion and network load in Mobile Ad Hoc Networks.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.34-34
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• 2000

One of the basic goals, when considering networks for communication in industrial control applications, is the reduction of complexity of related wiring harnesses. In addition, the networking offers the advantages for industrial control applications, such as ease of cabling, ease of changes in the cabling, ease of adding controller modules, etc. CAN (Controller Area Network) is generally applied in car networking in order to reduce the complexity of the related wiring harnesses. These traditional CAN application techniques are modified to achieve the real time communication for the industrial control applications. In this paper, we propose the method of CAN Identifier assignment for Real-Time network system. This method is can be used to scheduling messages on CAN for Real-Time network system. And also, the real-time network system is developed and the proposed moth(Ids are verified experimentally.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.362-362
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• 2000

The purpose of this thesis is to reduce force ripple of linear pulse motor(LPM) using neural network and to enhance precision. In order to this, we propose a new controller using a neural network to compensate disturbances. The structure includes adaptation block which learns the dynamics of the periodic disturbance and forces the interferences, caused by disturbances. The proposed controller compensates an unmodeled dynamics in the LPM. The neural network changes a current command to reduce position error and force ripple of the LPM. We compare proposed controller with PI controller. Simulation result shows that the proposed controller has better performance than a PI controller without neural network.