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金幸吉 여수대학교 1994 論文集 Vol.8 No.-
A satellite system communicating directly to a mobile terminal requires the basic link analysis of a small fixed terminal, but will have additional channel characteristics due to the motion of the terminal. This motion introduces spectral changes in the transmitted waveforms that can provoke future degradations relative to those of fixed-point systems. The effects are primarily originated by the time-varying multipaths that appear in trying to transmit an electromagnetic field from a satellite to a moving terminal or veichle. The multipath fading severely restricts the accurate data transmission over land mobile satellite networks. The fading plagues the propagation medium by imposing random amplitude and phase variations on the transmission signal. However, the relative effect of an undesired random variation is reduced by the presence of a strong ling-of-sight(LOS)component. It this paper, to analyze the data transmission performance of the satellite-to-ground mobile channel, a Rician fading model is used. For this model, the received multipath signal consists of the sum of a direct of LOS component and a fading component due to reflections from objects adjacent to the transmission path. Generally, when a data packet encounters a fade, it most likely contains errors and will have to be transmitted. Thus, the size of the packet is crucial to determine the performance of the channel. The present study finds for the first time the optimum packet size by applying an analytical model of the dynamics of the Rician channel. The performance criterion is based on the rate of information transfer through the network, the vehicle speed, and the modulation fade margin.
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多重 빔 多重衛星通信 시스템용 다이버시티 結合 軟決定 Viterbi 復號에 關한 硏究
金幸吉 여수대학교 1997 論文集 Vol.11 No.2
In this paper. I studied diversity combining methods for mobile satellite communication systems. Viterbi decoding are evaluated. Computer simulation clarifies that the pre-Viterbi-decoding maximal ratio combining method has better performance than other methods in Rician fading channels. The simulation results agree with the Pe(bit error probability) performance derived from the numerical analysis for slow fading using the approximate Pe performance of Viterbi decoding in AWGN(Additive White Gaussian Noise) channels and the probability density function of Rician fading.Applying this diversity method to the multi-beam mobile satellite communication systems, a satellite beam diversity reception scheme is proposed. A computer simulation result sohws that the proposed scheme decreases the packet error rate of the control signals to less than 1/100 around the satellite beam boundary.
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國際遭難周波數 2,182(2,183.4) KHz의 保護 對策에 대한 硏究
金幸吉 여수대학교 1993 論文集 Vol.7 No.-
2,182KHz, the international distress frequency for radiotelephony is protected severely, but crews of ship especially coastal fishing boat don't recognize the importance distress frequency, 2182KHz. As the result of it, they infringe radio regulations, cause international problems. Considering ensurance other frequencies, reduction of communication quanitity, dispersion of communication quantity is necessary.
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김행길 여수대학교 1998 論文集 Vol.12 No.2
The term called an informationized society has been used from when Alvintoffler, a culture-telling scholar of the later part of the nineteen- seventies, prescribed that an illiterate person is not the one who does not know the letters, but the one who is not able to get and deal with information by the computer terminal. The inundation of information is liable to bring the public society to so much danger causing social disorder that a high level of informationized society intensely requires an acute moral awakening. In order to keep pace with an informationized society, we should lay emphasis on how level of morality in the society overflowed with an wide range of knowledge. Especially, in the course of building an industrial society in Korea, we have been so careless in heightening moral consciousness that we are now falling into moral degradation. We must recognize this reality concerning moral corruption and try to elevate our society to a highly advanced moral standard to keep abreast of a rapidly developing informationized society. Many problems of industrial society, such as the city ward tendency of population, the environmental contamination, the exhaution of natural resources, etc. have arisen incessantly in our society, but if morally improved, such a society will surely make us live more happily, particularly in such a well-furnished society of information.
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김행길,이화용 한국정보통신학회 2000 한국정보통신학회논문지 Vol.4 No.2
In this study, the chamber size was designed and manufactured so as to make a resonance with microwaves in sterilizing moisture-contained food by making good use of microwaves. When the green-pea jelly which was made and sterilized for experimental usage with no addition of an antiseptic was left in the room temperature for 1 minute, 2 minutes or 3 minutes respectively, resulted in delaying more greatly the procession of change in quality of food for almost 7 to 15 days than in unsterilized food. As a result of experiment conducted above, it is considered to produce good results of decreasing the resource waste and environmental pollution, by lengthening the period of preservation and circulation of food.
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金幸吉 여수대학교 1995 論文集 Vol.9 No.-
To cope with the coming satellite broadcasting age, the communication systems used in advanced countries were already established in the beginning of 1980's and are now in the state of great development, and also the receiving mechanisms of satellite signals is now being commercialized. In the form of antenna composition, the receiving which can cover multi-wide areas is composed of a relatively big radiator, the feed horn more than one, one ejector which can cover the wide area and the first complex radiator and so forth. Even in Korea, a considerable number of receiving equipments of the satellite broadcastiong have been supplied and some enterprises have an technics of manufacturing antenna about analog FM-TV communication method. Particularly, in the days to come, since the satellite broadcasting will be in the trend of furnishing us with more various programs and the more improved quality of TV pictures than ever, it is absolutely required to develop receiving equipments of multichannels and orbits so that we can watch TV well furnished with various home-and-abroad programes. I hope that this study will contribute to the development of satellite broadcasting systems for this coming informationa age.
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金幸吉 여수대학교 1999 論文集 Vol.14 No.2
In this study, the chamber size was designed and manufactured so as to make a resonance with microwaves in sterilizing moisture-contained food by making good use of microwaves. When the green-pea jelly which was made and sterilized for experimental usage with no addition of an antiseptic was left in the room temperature for 1 minute, 2 minutes or 3 minutes respectively, resulted in delaying more greatly the procession of change in quality of food for almost 7 to 15 days than in unsterilized food . As a result of experiment conduct above, it is considered to produce good results of decreasing the resource waste and environmental pollution, by lengthening the period of preservation and circulation of food.
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조범식,김행길 여수대학교 2001 論文集 Vol.16 No.-
High level languages are rapidly becoming the standard programming methodology for embedded microcontrollers (MCUs), even for smaller 8-bit devices. The C language is probably the most widely used HLL(High Level Language) in MCUs, but will in most applications give an increased code size compared to assembly programming. The result is the ATMEL AVR MCU, that in addition to the optimized code size, is a true single cycle RISC (Reduced Instruction Set Computer) machine with 32 general purpose registers (accumulators) running 4-12 times faster than currently used MCUs.
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