• The Journal of the Acoustical Society of Korea
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• v.26 no.8
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• pp.381-389
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• 2007

In this paper, the measuring method of underwater acoustic communication channel characteristics in the shallow water using the autocorrelation characteristic of PN sequence and the undorwater communication channel analysis results from the received signal sample data are described. For measuring the underwater acoustic communication channel characteristics, two PN sequences are used as a transmitted data of I-channel and Q-channel of QPSK symbol and QPSK signal is transmitted with symbol rate of 5 kHz and carrier frequency of 25 kHz. In the receiver the received signal, which pass through 675 m and 1492 m, is sampled and then stored. Using the stored sample data, the scattering function, coherent time, delay power profile, spaced-tone autocorrelation function, delay spread, and coherent bandwidth of each propagation distance cases are analyzed. Based on the analysis results, several guidelines are suggested for the design and implementation of underwater transmission system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2272-2278
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• 2011

It is essential to various evaluate about statistic character of the signal and additional noise for optimization of the optical communication system. We expressed various error probability with the m which was bandwidth and a bit numerical function and carried out performance evaluation of a PIN receiver. This research analyzed the receiving sensitivity of the PIN receiver and verified reception sensitivity through computer simulation in the optical communication system. As a result, the receiving sensitivity for PIN receiver are $9.2{\times}10^4$ photon/bit for given error probability.

• Journal of information and communication convergence engineering
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• v.16 no.3
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• pp.166-172
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• 2018

A pseudo-random sequence generated by using a primitive polynomial, trace function, and Legendre symbol has been researched in our previous work. Our previous sequence has some interesting features such as period, autocorrelation, and linear complexity. A pseudo-random sequence widely used in cryptography. However, from the aspect of the practical use in cryptographic systems sequence needs to generate swiftly. Our previous sequence generated by utilizing a primitive polynomial, however, finding a primitive polynomial requires high calculating cost when the degree or the characteristic is large. It’s a shortcoming of our previous work. The main contribution of this work is to find some relation between the generated sequence and irreducible polynomials. The purpose of this relationship is to generate the same sequence without utilizing a primitive polynomial. From the experimental observation, it is found that there are (p - 1)/2 kinds of polynomial, which generates the same sequence. In addition, some of these polynomials are non-primitive polynomial. In this paper, these relationships between the sequence and the polynomials are shown by some examples. Furthermore, these relationships are proven theoretically also.

• The Journal of the Korea Contents Association
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• v.5 no.2
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• pp.157-164
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• 2005

The function of image in visual communication is increasing by development of information. It pursuits not only direct and concrete reappearance of information but also infinite possibility of image expression by image. It is also course of future image communication. Therefore, in this paper, if the images which pour out of rapid present society are communication means, it is formed to a point of view that improvement in function of communication will be performed excellently to interaction among consumers by recognizing meaning action process of methods of visual sign about user information processing which perceive Image of visual information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10C
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• pp.946-954
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• 2009

General RFID system has assumed that the communication channel between reader and back-end database is secure channel. However, the reader can be communicated with the database through insecure channel like the communication channel between the reader and the tag according to application environment. In this paper, we propose a new secure RFID mutual authentication protocol based on open network channel which assumed that all communication channels between the database, the reader and the tag are insecure communication channels. The proposed protocol uses a secure one-way hash function to provide authentication and integrity against all communication messages which exchanged on the open channels. In addition, we designed that the proposed protocol can provide forward secrecy by performing the database and the tag update their old secret key with a new secret key after finished mutual authentication.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.39-40
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• 2006

This paper modeled UWB system transmission channel in indoor environment. For channel modeling, we extracted transmission channel parameter, and then measured from 10MHz to 16.01GHz by using method of CIR(Channel Impulse Response) and CTF(Channel Transfer Function) in small room($5.5{\times}5.5m^2$) environment.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.165-166
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• 2007

This paper proposes an algorithm to improve the anti-theft function of the CAR_AV using the CAN(Controller Area Network) communication between CAR AV and cluster. Compare to the typical anti-theft algorithms like security code entering, the proposed one is more secure in most cases. The proposed algorithm is suitable for the recent automobile that employ the CAN network as the communication channel between their devices.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2225-2227
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• 2001

A wireless communication module for multiple nearfiled measurement and control module was developed. The function of the developed system are dual communication, concurrent multiple communication, PLC control, and A/D, D/A converting. The multiple communication approach is based on master-slave with sub-polling scanning concept.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.983-986
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• 2008

SCADA 시스템과 관련된 많은 표준 프로토콜이 등장하고 있는데, 앞으로 DNP, IEC61850, DLMS 등의 프로토콜들이 공존하는 형태로 발전할 것으로 예상된다. 본 논문은 이러한 프로토콜들의 공존을 위한 범용 SCADA 게이트웨이 개발을 위해 분석한 IEC 61850의 통신기능을 소개하고 있다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.12
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• pp.74-80
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• 2013

Generator faults does not happen more often than the transmission and substation facility faults. However, impacts on the power system by generator faults are very large. In order to minimize the impact of generator faults, generator protection and control system with high reliability is required. Most of the generator relay in generator protection and control system of large power plant of Korea is operated by imports from abroad. Accordingly, in order to accumulate source technology and increase the import substitution effect, localization of multi-function generator protection IED is being developed. This paper deals with the implementation of a multi-function prototype IED H/W, which can be command and data exchange through communication for measuring, monitoring, protection and control. And the IED specification, various relay elements, measurement elements, communication functions, module function, and test system for the prototype IED H/W are described.