• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.49-54
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• 2011

In this paper, End-to-End VoIP(Voice over Internet Protocol) performance over large scale MANET(Mobile Ad-hoc Networks) is evaluated. VoIP implementation model, which can be used for large scale MANET, is suggested through this evaluation. VoIP simulator based on NS-2 network simulator is used for performance measurement. Call connection ratio as a connection performance, MOS and network delay as a transmission performance, packet loss rate as other performance is measured with this simulation. Finally, maximum $10{\sim}15km^2$ as a single MANET, 500 nodes and 100 call connections is suggested for VoIP implementation and operation conditions over large scale MANETs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1730-1736
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• 2013

Slanted and chirp interdigital transducer(IDT) configurations were studied for generating the surface acoustic wave(SAW) with wide bandwidths on a piezoelectric substrate. These devices can be applied to manipulate optical path of light along the waveguide, ultimately used for optical switches and holographic image implementation. Prior to fabrication, the coupling of modes(COM) modeling and simulation were performed to extract optimal design parameters. The optimally designed wideband device showed wide bandwidth of 30MHz, low insertion loss of -25dB, and abrupt side suppression ratio (SSR). Several design conditions were determined during device implementation, such as slanted angle, aperture length, number of fingers, and central frequencies of IDTs. These factors were experimentally analyzed and described in details in this paper.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.626-629
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• 2003

In this paper, a system that implementation of Biometric System Using RF-ID. We organize a certification system which the security is strengthened, the information is flowed out and the presentation will do the possibility not to be abused. The loss of the credit card and problems which there is many of forgery back are happening. To solve such problems, We organized the system to use after we stored a fingerprint data at RF Card and going through certification necessary formalities. Various research to be related uses this system and is predicted. The development to common use goods will be possible through a certification procedure.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.103-111
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• 2014

This study was to develop the flood analysis module (FAM) for implementation of a web-based real-time agricultural flood management system. The FAM was developed to apply for an individual watershed, including agricultural reservoir. This module calculates the flood inflow hydrograph to the reservoir using effective rainfall by NRCS-CN method and unit hydrograph calculated by Clark, SCS, and Nakayasu synthetic unit hydrograph methods, and then perform the reservoir routing by modified Puls method. It was programmed to consider the automatic reservoir operation method (AutoROM) based on flood control water level of reservoir. For a $15.7km^2$ Gyeryong watershed including $472{\times}10^4m^3$ agricultural reservoir, rainfall loss, rainfall excess, peak inflow, total inflow, maximum discharge, and maximum water level for each duration time were compared between the FAM and HEC-HMS (applied SCS and Clark unit hydrograph methods). The FAM results showed entirely consistent for all components with simulated results by HEC-HMS. It means that the applied methods to the FAM were implemented properly.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.12
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• pp.5422-5441
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• 2016

Despite the abundant literature in the field, there is still the need to find a time-efficient, highly accurate, easy to deploy and robust localization algorithm for real use. The algorithm only involves minimal human intervention. We propose an enhanced Received Signal Strength Indicator (RSSI) based positioning algorithm for Wi-Fi capable devices, called the Dynamic Weighted Evolution for Location Tracking (DWELT). Due to the multiple phenomena affecting the propagation of radio signals, RSSI measurements show fluctuations that hinder the utilization of straightforward positioning mechanisms from widely known propagation loss models. Instead, DWELT uses data processing of raw RSSI values and applies a weighted posterior-probabilistic evolution for quick convergence of localization and tracking. In this paper, we present the first implementation of DWELT, intended for 1D location (applicable to tunnels or corridors), and the first step towards a more generic implementation. Simulations and experiments show an accuracy of 1m in more than 81% of the cases, and less than 2m in the 95%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.740-749
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• 2015

In the visible light (VL) communication based on the conventional LED lights, depending on the increase of the communication range, the signal received at the photodiode of the VL receiver has usually the random distorted and decreased amplitude due to the path loss and fading effects of the VL channel. In order to overcome this problem, we propose, design, and implement the visible light communication circuit based on the comparator threshold voltage, where has a built-in distance compensation function. In addition, the performance of the proposed technique is evaluated and analyzed depending on the distance and communication speed through comparing the proposed VLC system based on the threshold voltage with the conventional one.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.3
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• pp.753-758
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• 2011

According to the needs for equipment performance, reliability, and performance for impending time to guarantee its viability, various redundancy techniques have been used in many military systems. Typically, one of redundancy schemes to increase the viability of the system is to configure a network between two processes. However, when some failure or loss in a physical network occur, redundancy schemes may not operate well. In this paper, we present a protocol scheme of VMEbus master and slave of a shared memory region, interrupts, and a dedicated task communication. Specifically, we confirm the validity of the presented scheme through the direct implementation of the protocol and some experimental results.

• The Transactions of the Korea Information Processing Society
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• v.4 no.8
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• pp.2060-2069
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• 1997

Information processing using computer in generalized in the office automation. In spite of to be integrate and concise form of document through computer network, signature of document with hand have processed as ever. The security on document flow out severely unjust by reason of increment inverse function of computer. Because of revelation secret of enterprise result from unjust outflow, lots of loss of self-enterprise is occured. In this paper, we used efficiently document using the method, electronic approval system with encryption, for the resolving above problems. Also we persue maintenance of security for the important document and process document signature rapidly. Finally, we design and implementation of electronic approval system that take one's share of function between server and client using to be transformed Vernam's encryption technique in stored document.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12C
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• pp.181-189
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• 2001

In this thesis, a policing algorithm is proposed, which is one of the traffic management function in ATM networks. The proposed algorithm minimizes CLR(Cell Loss patio) of high priority cells and solves burstiness problem of the traffic caused by multiplexing and demultiplexing process. The proposed algorithm has been implemented with VHDL and is divided into three parts, which are an input module, an UPC module, and an output module. In implementation of the UPC module\`s memory access, memory address is assigned according to VCI\`s LSB(Lowest Significant Byte) of ATM header for convenience. And the error of VSA operation from counter\`s wrap-around can be recovered by the proposed method. ANAM library 0.25 $\mu\textrm{m}$ and design compiler of Synopsys are used for synthesis of the algorithm and Synopsys VSS tool is used for VHDL simulation of it

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.503-506
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• 2010

In this paper, we apply the system in VMEbus to increase the stability and viability to implement a redundant network protocol. Typically, methods for increasing the viability of the system applied by the redundancy scheme between the two processes by configuring the network in between the two is to implement redundancy. However, the physical network in the process of the failure or when the loss function may not perform properly. These issues are complementary processes as a way to ensure stability between the VMEbus communication protocol is presented through a redundant network. In this paper, a direct implementation of the protocol and experimental results confirm the validity of these measures is to.