• Fire Science and Engineering
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• v.16 no.1
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• pp.30-38
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• 2002

Occurring fire or burning bushes beneath overhead power lines have caused system disturbances in many countries. In this study, various tests in the simulated condition of power lines were conducted so as to investigate the reduction in insulation strength caused by combustion flame. Characteristics of the ac and dc flashover voltages in the vertical needle-plane, sphere-plane and rod-plane electrode system were investigated when the combustion flames were present near the high-voltage electrode. As the results of an experimental investigation, It was found that the average reduction characteristics of flashover voltages with the sphere-plane system, in comparison with the no-flames case, were about 1/3 times when the ac voltages were applied.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.85-92
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• 2008

Occurring forest fire or burning bushes beneath overhead transmission lines have caused breakdown disturbances of the system in many countries. In this study, experiments for flashover characteristics in the simulated condition of vertical power lines were conducted so as to investigate the reduction in insulation strength caused by combustion flame. As the results of an experimental investigation, it is demonstrated that flame can reduce breakdown voltages of the model lines according to height(h) of flame. The breakdown voltages were decreased with decreasing the height(h) of flame it can be seen that the average reduction of flashover levels, in comparison with the no-flame case, are 46.2[%] for h=9[cm] and 62.5[%] for h=3[cm] when ac voltage is applied.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2042-2048
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• 2014

In medium voltage electrical distribution networks, reforming the loss reduction is important, and in line with this, the issue of system engineering and use of proper equipment Expansion of distribution systems results in higher system losses and poor voltage regulation. Therefore, an efficient and effective distribution system has become more important. So, proper selection of conductors in the distribution system is crucial as it determines the current density and the resistance of the line. Evaluation of aging conductors for losses and costs imposed in addition to the careful planning of technical and economic networks can be identified in the network design. In this paper the use of imperialist competitive algorithm; genetic algorithm; is proposed to optimal branch conductor selection and reconstruction in radial distribution systems planning. The objective is to minimize the overall cost of annual energy losses and depreciation on the cost of conductors to improve productivity given the maximum current carrying capacity and acceptable voltage levels. Simulations are carried out on 69-bus radial distribution network using genetic algorithm approaches to show the accuracy as well as the efficiency of the proposed solution technique.

• Journal of the Korea Institute of Building Construction
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• v.12 no.4
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• pp.401-414
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• 2012

The adoption of Green Frame is expected to provide economic benefits, since construction costs are reduced by the in-situ production of precast concrete column and beam. The cost reduction can ultimately be realized by saving transportation costs and the overhead and profit of PC plants. The cost structure of Green Frame, which is built up using composite precast concrete members, is similar to that of a bearing-wall structure, but the difference in construction process has resulted in some cost differences for a few items. In particular, production and installation is the principal work involved in Green Frame made by precast concrete members, while form and concrete work is the principal work for a bearing-wall structure. As such, the rental time and fee for a tower crane should be compared through time analysis. To verify reliability, this study focused on developed residential projects to estimate the construction costs. Through this analysis, it was found that the costs of Green Frame were 1.57% lower than the costs of bearing-wall structure. The results of this study will help in the development of a management plan for the structural work of Green Frame.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.2
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• pp.179-185
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• 2020

DRAM is a major component of the main memory system. As the operating system evolves and application complexity and capacity increases, the capacity and speed of DRAM are also increasing. DRAM should perform a refresh action of periodically reading and then re-storing stored values, and the accompanying performance and power/energy overhead embodies characteristics that worsen as capacity increases. This study proposes an energy efficiency improvement technique that efficiently stores the rows that need to be refreshed within 64ms and 128ms using the bloom filter for cells with the lowest retention time of electrons. The results of the experiment showed that the proposed technique resulted in an average 5.5% performance improvement, 76.4% reduction in average refresh energy, and 10.3% reduction in average EDP.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1308-1313
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• 2008

Neighbor knowledge in wireless ad hoc networks provides important functionality for a number of protocols. The neighbor knowledge is acquired via Hello packets. Hello packets are periodically broadcasted by the nodes which want to advertise their existence. Usage of periodic Hello packet, however, is a big burden on the wireless ad hoc networks. This paper deals with an approach where each node acquires neighbor knowledge by observing not only Hello packets but also broadcasting packets. Analysis and computer simulation results show that the method using broadcast packets offers significant improvement over the method using Hello packet only. When the required hello packet transmission interval and the average broadcasting interval are equal, the overhead reduction is about 42%.

• ETRI Journal
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• v.27 no.5
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• pp.511-524
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• 2005

In this paper, we propose a novel hardware architecture for an intra-prediction, integer transform, quantization, inverse integer transform, inverse quantization, and mode decision module for the macroblock engine of a new video coding standard, H.264. To reduce the cycle of intra prediction, transform/quantization, and inverse quantization/inverse transform of H.264, a reduction method for cycle overhead in the case of I16MB mode is proposed. This method can process one macroblock for 927 cycles for all cases of macroblock type by processing $4{\times}4$ Hadamard transform and quantization during $16{\times}16$ prediction. This module was designed using Verilog Hardware Description Language (HDL) and operates with a 54 MHz clock using the Hynix $0.35 {\mu}m$ TLM (triple layer metal) library.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.327-330
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• 2005

In this paper, we proposed that technique for reducing trailing artifact in MPEG-4 video. low bit-rate video is occured trailng artifact which remain part of moving object. Because MEMC doesn't work well in the degraded video. The proposed trailing artifact reduction approach has at its core three main steps. First step is to detect trailing artifact. Second step is applied intra block coding to remove trailing artifact. Finally, bit-rate control algorithm is used. Experimental result using an MPEG-4 based encoder indicate that the proposed method has overhead(bits) of about 2 percent and proposed method effective reduce or eliminate trailing artifact

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1089-1092
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• 1998

Conventional floating-point adders have one data-path that is used for all operations. This paper describes a floatingpoint adder eeveloped for low power consumption, which has three data-paths one of which is selected according to the exponent difference. The first is applied to the case that the absolute exponent difference (AED) of two operands is less than 1, and the second is for 1

• Journal of information and communication convergence engineering
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• v.14 no.2
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• pp.89-96
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• 2016

In mobile communication, there are various types of handoff for the support of all forms of mobility. Proxy mobile IPv6 (PMIPv6) enables local network-based mobility management of a mobile node without any effect of mobility-related signaling. Recently, PMIPv6 has been considered for supporting mobility management in LTE/SAE-based mobile networks. To support seamless mobility in heterogeneous mobile networks, the overall cost of handoffs needs to be minimized and the procedure should be guaranteed to be secure. However, the reduction of the authentication cost has not been fully investigated to provide seamless connectivity when mobile users perform a handoff between the PMIPv6 domains. This paper proposes secure pre-authentication schemes, completing an authentication procedure before performing a handoff, for a fast handoff in PMIPv6. Analytic models have been used for measuring the authentication latency and for the overhead cost analysis. In addition to providing fast authentication, the proposed pre-authentication schemes can prevent threats such as replay attacks and key exposure.