• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.6
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• pp.1-5
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• 2010

We propose an algorithm which can classify the system should use a PI controller, which have a weak high frequency attenuation characteristics near the critical frequency. To classify the system, we use a time delay element to calculate a gain attenuation rate near the critical frequency. The proposed algorithm also can design PI controller with the given magnitude margin and phase margin specification. The proposed algorithm uses time delay element and saturation function to identify the one point information in frequency domain. We justify the proposed algorithm via the simulation.

• The KIPS Transactions:PartC
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• v.8C no.3
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• pp.367-372
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• 2001

지도제작, 해양생태감시, 기상관측, 및 우주환경감시 등의 분야에 이용되는 저궤도 위성을 관제(위성추적, 원격측정 및 명령)하기 위해 본 논문에서는 최적의 PM 변조지수를 결정하는 방법을 기술하고 수신 데이터의 성능을 평가한다. 이 저궤도 위성인 아리랑 위성은 한국에서는 첫 번째 저궤도 위성이며 1999년 12월 발사되어 현재 임무를 충실히 수행하고 있다. 아리랑 위성 관제시스템의 파라미터에 의해 위성링크를 설계하면, PB 원격측정 신호의 최적 변조지수는 Eb/No마진과 PFD마진의 교차점이 되며 1.92라디안으로 결정된다. 또한 위성의 통과시간에 따라 예측되는 BER은 RT모드에서 최고의 성능을 나타애고, RT+RNG모드에서 최악의 성능을 나타내기 때문에 데이터 전송순서를 위성의 통과시간에 따른 BER 성능 순서인 RT, PB, RT+RNG모드의 순서로 결정함으로써 수신성능을 높일 수 있다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.341-350
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• 2007

In this paper, the derivation of protection ratio is newly proposed for the detailed planning of frequency coordination in microwave relay networks, and computed results for protection ratio of co-channel and adjacent channel are illustrated over the actual system and its frequency. It is shown that the suggested method based upon availability prediction can be expressed in terms of composite fade margin, interference-to-noise ratio(I/N), net filter discrimination, and system parameters. According to results, for 6.7 GHz, 60 km, 64-QAM, and I/N= -6 dB at BER $10^{-6}$, composite fade margin and co-channel protection ratio provide 25.5 and 50.7 dB, respectively. Also, net filter discrimination and adjacent channel protection ratio are obtained as 26.3 and 24.4 dB, respectively, at the first adjacent channel of 40 MHz. The proposed method provides some merits in computing protection ratio for microwave relay networks in view of an easy extension and practical applications considering more detailed and various system parameters.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.871-881
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• 2001

In this paper, the effect of soft handoff technique on CDMA cell coverage is analyzed in a lognormally shadowed channel, which uses the Hata propagation model, Also, the rate of increase for the cell coverage is analyzed by calculating the hard and soft handoff margin. When the outage probability is 0.02 and the standard deviation of the received signal is 2.5 dB in a lognormally shadowed channel, the transmit power of the mobile station which is located in the cell boundary is increased by the hard handoff margin of 5.13 dB and by the soft handoff margin of 3.68 dB, respectively. So, the rate of increase for the cell coverage is 1.39 in case of using the soft handoff technique. It is shown that if the (E$\_$b//N$\_$0/)$\_$req/ value is 7 dB, the cell coverage of the CDMA cellular system with soft handoff technique in city area is 3.33 km in case of the 850 MHz frequency and 1.36 km in case of the 1900 MHz frequency. Also, the accurate cell coverage with soft handoff technique is supported that could be serviced by the base-station in CDMA cellular system.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.3
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• pp.8-16
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• 2014

This paper analyzes the effects of sideslip angle(SA) on the buzz margin of supersonic intake. The buzz margin is assumed to be stabilized by a controller which generates command depending only on the longitudinal sensor measurements. The analysis is performed based on three dimensional CFD results with which the sensor measurements can be simulated. In such a control system based on the longitudinal measurements, unexpected lateral flow perturbation results in the increase in the total angle of attack(TAoA), that causes the degradation of the engine intake performance. As a consequence, it is shown that the control stability is reduced such that additional control margin needs to be secured.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.233-236
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• 2005

본 논문에서는 중첩되는 두 개 이상의 PAN의 무선영역이 간섭을 일으키는 경우와 다수의 무선기기가 동시에 접속하는 경우에 대비하여 간섭마진 정보를 이용한 가변 전송율을 갖는 UWB 통신 시스템을 제안한다. 또한, 가변 전송율 UWB 통신 시스템을 불완전 다중접속 간섭 환경에서 고정 전송율을 갖는 UWB 통신 시스템과의 성능을 비교 분석하고 전송효율을 평가하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.133-142
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• 2006

This paper suggests an efficient method of protection ratio(PR) calculation and shows some results of point-to-point radio relay system for frequency coordination. The proposed PR can be expressed as a function of C/N of modulation scheme, noise-to-interference ratio(N/I), multiple interference allowance, fade margins of multi-Path and rain attenuation and net filter discrimination. And PR calculation is performed in view of fade margin, modulation scheme, distance, and interference for actual point-to-point radio relay frequency. According to results for 6.2 GHz, 64-QAM and 60 km at BER 10-6, fade margin and co-channel Protection ratio reveal 41.1dB and 74.9 dB, respectively The merit of presented method provides a systematic and easy calculation by means of PR correction factor related with various parameters and can apply the same concept to frequency coordination of millimeter wave radio relay system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.8
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• pp.138-144
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• 2004

Satellite generates a complex electromagnetic noise by conducted and radiated coupling effect of the various electrical instruments. This noise may cause serious problems on the satellite system. To minimize the electromagnetic coupling effects and maintain the system safety margin, system noise reduction technique should be applied from the beginning of the system design. The KOMPSAT-2 system is evaluated by measuring the conducted noise on system electrical power leads and verifying a 6dB system safety margin under the complex noise environment with current injection. This paper describes the KOMPSAT-2 system evaluation result performed on ETB(Electrical Test Bed) and the analysed noise element, the analysed result will be reflected on FM(Flight Model) EMC test.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.89-98
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• 2006

This paper describes signal attenuation characteristics as splicing the output on LVDT for stability and reliability of switching mechanism, which is developed to use common signal between FLCC and EDFLCC, on T-50 aircraft. The method of test is classified a Pspice simulation and an actual hardware evaluation. The difference of error margin for two methods is 10times, the latter higher. The result in this experiment shows that the signal attenuation as splicing the output on LVDT doesn't affect and the static error margin is 53% for develope the EDFLCC.

• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.169-173
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• 1999

We have experimentally investigated the eye margin characteristics of intensity modulated 10Gb/s NRZ signals in optically amplified systems depending on optical signal-to-noise ratio and chromatic dispersion. For the practical system application, the minimum optical signal-to-noise ratio was 25 dB. We utilized the negative chirped transmitter and a dispersion compensation fiber to compensate the chromatic dispersion in single mode fiber. We found the optimum eye opening and receiver sensitivity in case of the residual dispersion of 0~+935 ps/nm.