• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.226-230
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• 2000

In this paper, we implemented the QPSK demodulator with a CPLD chip, and examined the results. DD(Decision Directed)-Gardner algorithm is used for STR loop and Decision-Directed algorithm is used for CPR loop. The speed of the QPSK demodulator implemented in FLEX10K chip can be guaranteed approximately 2[Mbpsl] transmission speed. In practical designed by ASIC, the speed is faster than that of CPLD by 5-6 times.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.07a
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• pp.62-65
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• 2020

본 논문에서는 ATSC3.0 Layered-Division-Multiplexing Multiple-Inputs-Multiple-Outputs 방송 시스템에서 Core-Layer(CL) 신호 복조 시 기존 Gaussian-Approximation(GA) 기법과 Partial-GA(PGA) 기법을 선택적으로 사용하여 PGA 기법과 성능은 거의 동일하며 복잡도는 더 작은 새로운 Hybrid PGA(HPGA) 복조 기법을 제안하고자 한다. 제안된 복조 기법은 수신단 신호의 Injection Level(IL) 값이 송신 IL보다 높아 CL 신호 입장에서 채널 상태가 좋을 경우 GA 기법을 사용하고, 반대로 수신단 IL 값이 송신 IL보다 낮아 채널 상태나 좋지 않을 경우 성능을 우선한 PGA 기법을 사용하게 된다. 실험 결과 성능은 PGA 기법과 거의 동일하고 복잡도는 PGA 기법의 복잡도 대비 약 25% 정도 작아짐을 보인다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.82-89
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• 2014

This paper discusses the methods for reducing the sampling time quantization errors of the body dither type ring laser gyroscope. A ring laser gyroscope has the angle quantization error which is generated by the frequency counting method of the laser beat signal and sampling time quantization error which is generated by the demodulation method for eliminating the body dithering in which the sampling periods are fitted to the dither periods. Generally, because the dither periods are longer than the calculation periods of the inertial navigation system, vehicle navigation errors are produced by long time attitude update missing during the vehicle move with a high dynamical motion. In this paper, the double demodulation method is proposed for reducing the sampling time quantization error and its effects under the dynamic situation are confirmed by simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.99-108
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• 1999

In this paper, we propose $\pi$/4 QPSK scheme with block modulation algorithm, which can reduce preamble in order to transmit ATM cell efficiently in the uplink channel of LMDS, and also designed a new carrier recovery circuit which can improve carrier synchronization performance of block demodulation algorithm. The $\pi$/4 QPSK scheme employing the proposed block modulation algorithm achieved efficient frame transmission by making use of a few preamble when carrier synchronization, symbol timing synchronization and slot timing synchronization were performed by burst data of ATM cell in LMDS environment. For performance evaluation of the proposed method, a simulation analyzing the variation of carrier synchronization, symbol timing synchronization and slot timing synchronization using LMDS environment and burst mode condition was executed. In the simulation, the proposed method showed a good performance even though the reduced preamble as a few aspossible when carrier synchronization, symbol timing synchronization and slot timing synchronization is performed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.11
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• pp.2081-2093
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• 1994

In this study, we design and implement 64 QAM demodulator which has 155 Mbps, first level of CCITT G707 SDH(Synchronous Digital Hierachy) for STM 1 signal transmission. Carrier recovery which effects the demodulator performance uses decision feedback carrier using 8 bits A/D converter. Also, PSF(Pulse Shaping Filter) is 7 order elliptic filter. Carrier recovery circuit is designed and implemented digital type which use high 3 bits of 8 bits conversion data as data and the order low bits as error data and hybrid type which use VCO and analog integrator. Therefore we obtain stable performance recovery.

• Journal of Broadcast Engineering
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• v.12 no.1 s.34
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• pp.2-10
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• 2007

We analyzed the receiving performance of the DVB-S2 transmission system in the BC(Backward Compatibility) mode. The transmitter employs the hierarchical modulation, and the receiver can be implemented by the direct demodulation or the hierarchical demodulation. The performance of each demodulation scheme is analyzed by a statistical method and a computer simulation for the AWGN and nonlinear channels. The ratio of the LP/HP streams which is proper in the domestic satellite broadcasting environments, is also suggested.

• 전자공학회논문지 IE
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• v.49 no.2
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• pp.46-51
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• 2012

Transmit signal of Enhancement Layer in AT-DMB system is received by Coherent Detection, but in Base Layer of AT-DMB, a differential modulation and demodulation is adopted, same as the T-DMB. Especially for the coherent dectection of enhancement layer in AT-DMB system, a channel estimation must be employed. In this paper, I will show that the BER performance of Base-Layer in AT-DMB system will be improved by using the channel estimation information. The suggested method is focusing the constallations after Equalizaing to the nearlest ${\pi}$/4-shift DQPSK constallation points. Simulation results show that for the non-coding environment, the BER performance of AWGN channel, about 2-dB gain can be achieved at $10^{-4}BER$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.3
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• pp.212-217
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• 2016

The S-band receiver for Low Earth Orbit satellite is designed and fabricated as engineering model. Demodulator is implemented by using FPGA for extension of demodulator method. The receiver consists of RF Block, Digital demodulator and Power stage and has a Doppler tracking function to compensate a frequency shift that occur on the operation. The measured results of fabricated receiver show BER of less than $1.0{\times}10^{-6}$ at -110dBm RF input power and equipped a frequency tracking of ${\pm}100KHz$ relative to the center frequency. TID test was satisfied with the results of the test criterion is 10krad.

• Food Science and Preservation
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• v.23 no.1
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• pp.127-130
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• 2016

The appearance and physicochemical characteristics of a native jujube (called Yak jujube) and Bokjo jujube were compared in this study. Our results revealed that the native jujube had smaller size, lower hardness, and higher contents of sugar, crude protein, crude fat, crude ash, dietary fiber, and calcium contents, when compared to that of Bokjo jujube. Therefore, native jujube is softer and sweeter, with higher general nutrient content, despite being smaller than that of Bokjo jujube.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.4
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• pp.730-736
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• 2008

We proposed and implemented new DDC system which overcomes the difficulties including lack of flexibility of modifications of frequency which is the problem of previous frequence oscillator and synchronization. New DDC system can create frequence in two decimal points. Moreover, due to its usage in adjusting to frequence clock which is required by many consumers, laser distance instrument can reduce its error; thus, implementation of system is capable of high precision distance measurement can be performed.