• Journal of Satellite, Information and Communications
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• v.6 no.1
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• pp.12-18
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• 2011

Signal fading due to rain is one of the most significant factors degrading link quality in satellite communication systems. Adaptive transmission is considered to be the most efficient means to countermeasure the rain attenuation. In order to develop and design a good adaptive transmission system, we need a dynamic rain attenuation model which can synthesize time series of rain attenuation. In this paper, we present a modeling technique for dynamic rain attenuation using a Markov process. We derive statistical fading properties of the rain attenuation data measured in second time interval and define four states in the Markov process. We synthesize the rain attenuation data using the 4-state Markov process, and compare statistical properties of the simulated data to those of the measured data.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.1
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• pp.60-66
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• 2004

In order to analyze voltage, current electrical power, harmonic and so on of electrical load equipments, electrical power analysis by real measurement rather than mathematical modeling is necessary, and plan of countermeasure for efficient management, energy frugality and accident prevention of electrical equipments using it is possible Especially, electrical power analysis by real measurement is indispensable in order to consider countermove of harmonic occurred by nonlinear load So, in this paper, we developed DSP(Digital Signal Processor) based low price date aquisition system, and verified it's ability by performing measurement and analysis of electrical power and harmonic in the real power system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.1000-1004
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• 2008

As performance of medical air compressor improve, the problem of noise increased. Noise is very important to medical air compressor because most of this installed inside of building. The main goal of this paper is show TPA (Transfer Path Analysis) result for contribution analysis using PAK system. Generally, the conventional TPA method consists of two steps. First, transfer functions between output sound and sources are measured by excitation experiment. Second, transferred sound in each transfer path is generated by multiplying the transfer function and the sound source signal. Then, if the output sound synthesized from all transferred sounds doesn't give good agreement with the measured output sound (i.e., the accuracies of the transfer functions are low), setting a suitable countermeasure guideline becomes difficult. For obtaining highly accurate transfer functions, eliminating correlations among transfer functions and noise included in the measured data are necessary. In the new method with PAK system, the vibration acceleration and sound signals around the sound sources and the output sound were measured simultaneously to obtain the transfer functions when compressor was operating. By applying PAK system, a highly accurate and efficient transfer path analysis method was developed that does not require an excitation experiment.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.1
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• pp.79-88
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• 2001

The target such as aircraft operates flares to protect itself from the missile. In general, Infra-red(IR) flares that are hot bodies radiating energy considerably greater than it does, so cause the missile to guide the flare instead of the target. For a precise target tracking in spite of a presence of flares, therefore, the seeker should discriminate the target signal from various clutters including the flare and the background. In this paper, we simulated 2-color rosette scan seeker using IR and UV(UltraViolet) bands. In each wave band, we analyzed the radiant distributions of the target, the flare, and background. These results showed that a simultaneous process in two bands can detect precisely the target.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.777-786
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• 2001

In this paper, as one of countermeasure techniques for a frequency selective fading, a digital slope equalizer(DSE) for 64-QAM digital radio relay system is analyzed in terms of principle, channel modeling, and digital implementation. Also computer simulations have been performed for DSE with a complex 13-tap adaptive time domain equalizer chip. It is shown that about 4.5 dB improvement in system signature can be obtained at the channel edge, and a variety of simulated results are reviewed in view of DSE modeling limit, operating frequency, control coefficient, signal constellation, and system signature. Finally, the functions of DSE chip confirmed up to 61 MHz clock operation are illustrated.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.658-670
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• 2007

Most railroad accidents are due to human errors. In particular, most of the causes of these accidents are faults of an engine driver, such as lack of signal confirmation, insecure braking, driving by guess or force of habit. This paper identifies a problem(s) by analyzing accidents for the past 10 years and also seeks a solution to train good engine drivers in order to prevent railroad accidents. In summary, what is needed are: 1) proper placement of various manpower, 2) proper training of engine drivers, 3) proper legislation for a 2-man on board system, and 4) proper reformation of personnel management.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.309-317
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• 2017

This paper proposes a compact K-band radar applied to a miniature proximity fuze for the active defense system. In this terrestrial environment, it is not easy to detect approaching small targets because the clutter is scattered. In addition, it is difficult to miniaturize the radar for the small proximity fuze while improving the target accuracy of the radar in such environments. To solve these difficulties, this study presents system analysis and design, antenna design, and transceiver and signal processor design of the compact K-band radar. Some test results are presented and the results are analyzed, the validity of the proposed study is examined.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.87-96
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• 2012

This research overcomes limit of prevention of disasters connection manual that was stopping in existing administrative formality presentation, and allowed purpose in substantial prevention of disasters countermeasure presentation through powerful engineering access. Did operation plan manual Tuesday in contiguity crossing that can reduce confusion by vehicleses that detour by contiguity IC of disaster point to do unusualness ashes in freeway section for this and solve jam-up phenomenon that occur by processing way insufficiency for roundabout way vehicles when happen. Metropolitan areas to target type classification in the highway along the highway adjacent to the intersection at Main Line Blocking optimum operating point analysis and an analysis of countermeasures in case of disaster, the lower the road entering the highway depending on the type of operating at the intersection were different. Depending on the results of analysis, while each point of a disaster, according to the characteristics of geometric conditions, traffic conditions, identify and determine the operating room and the adjacent intersection of media, and building systems to promote the driver if the quick initial response from the impending disaster situations and the safety of drivers can be considered secure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11B
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• pp.1696-1703
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• 2010

Increased demand for military satellite communications system and due to the depletion of resources of existing satellite communications frequencies, Ka-band and EHF-band satellite communication systems is growing demand for development. As a result, the study of rain attenuation mitigation for Ka/EHF-band frequencies has been achieved. The method to compensate rain attenuation on Ka-band(20/30) using the signal power measurement function in Digital Transponder of Next Military Satellite has been proposed in this paper. This method is more effective than generally used method by Beacon and UPC(uplink power control) in giving the precise rain attenuation measurement and correction.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.277-280
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• 2011

VoIP is a technology of voice communication, using the existing internet network which sends and receives voice packets. VoIP has an advantage that VoIP is cheaper than an existing telephony, and the tech is vitalized lately. But recently you can download Volp Application in the Market that have a vulnerability(Anyone Can Upload). This weakness is wrongfully used that People are downloaded by encouraging about malignant code is planted. Signal intercepts indicates from this case. and paralysis by DDoS Attack, bypass are charged for hacking. Judging from, security threat of VolP analysis and take countermeasures. In the thesis we analyze the VoIP security caused on 'Soft Phone' and 'Smart Phone', and figure out security policies and delineate those policies on the paper.