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저속 PLC 모뎀에서의 Chirp 신호 방식과 시스템 구현에 관한 연구
정영화,이상건,Jeong, Young-Hwa,Sang-Gun Lee 한국정보기술전략혁신학회 2004 情報學硏究 Vol.7 No.3
The representative communication method which is applied in the low-speed power line communication modem with 60bps is single carrier method. It has been used mainly for the control. The single carrier method is very sensitive to a power line communication channel environment. Specially, the severe attenuation of the transmission signal according to the notch characteristics of channel becomes the main cause of communication error. Domestic power line channel environment has this notable feature. In this paper, we implemented the low-speed power line communication system which used the chirp signal method to be strong in notch and noise characteristics. In this research, we proposed the method which transmits 1- '1 Unit symbol Chirp signal' with a 100${\mu}s$ time within 1ms for 1 bit. Also it applied for the Convolution code for an error correction and the Manchester code for a collision perception and an error detection. It used the method which uses the bit correlator for signal detection in the receiver parts. We confirmed that the communication method of the chirp method has a excellent performance compared to single carrier methods with a result of experiment of the low-speed power line communication system with the 60bps.
정영화,Jeong Young-Hwa 한국정보기술전략혁신학회 2003 情報學硏究 Vol.6 No.3
본 논문은 전력선 통신 실험을 보다 빠르고 효율적으로 수행할 수 있는 전력선 채널 모델링에 관한 것이다. 용량성 부하 채널 시뮬레이터는 댁내망 전력선 모뎀 개발에 있어서 필수적인 실험 장비이다. 실제 전력선 채널 환경을 모델링한 이 실험 장비를 이용한 총 245 개의 용량성 부하 채널에 대하여 주파수 응답법에 의한 채널 모델링을 행하였다. 용량성 부하 채널 시뮬레이터를 사용한 실험 데이터 결과와 모델링된 채널 필터를 통과한 결과를 비교하였을 때 큰 오차 없이 실제 전력선 통신상의 용량성 부하 실험을 대체할 수 있음을 확인하였다.
Stop-and-Go 플래그를 가지는 새로운 블라인드 등화 알고리즘
정영화,Jeong, Young-Hwa 한국정보기술전략혁신학회 2005 情報學硏究 Vol.8 No.3
The CMA and MMA blind equalization algorithm has the inevitable large residual error caused by mismatching between the symbol constellation at a steady state after convergence. Stop-and-Go algorithm has a very superior residual error characteristics at a steady state but a relatively slow convergence characteristics. In this paper, we propose a SAG-Flagged MMA as a new adaptive blind equalization algorithm with a Stop-and-Go flag which follows a flagged MMA in update scheme of tap weights as appling the flag obtaining from Stop-and-Go algorithm to MMA. Using computer simulation, it is confirmed that the proposed algorithm has an enhancing performance from the viewpoint of residual ISI, residual error and convergence speed in comparison with MMA and Stop-and-Go algorithm. Algorithm has a new error function using the decided original constellation instead of the reduced constellation. By computer simulation, it is confirmed that the proposed algorithm has the performance superiority in terms of residual ISI and convergence speed compared with the adaptive blind equalization algorithm of CMA family, Constant Modulus Algorithm with Carrier Phase Recovery and Modified CMA(MCMA).
가변 스텝 크기 MSAG-GMMA 적응 블라인드 등화 알고리즘의 성능 평가
정영화,Jeong, Young-Hwa 한국인터넷방송통신학회 2018 한국인터넷방송통신학회 논문지 Vol.18 No.3
본 논문은 가변 스텝 크기를 가지는 MSAG-GMMA(modified Stop-and-Go generalized multi modulus algorithm) 적응 블라인드 등화 알고리즘의 성능 분석에 관한 것이다. 제안한 알고리즘은 등화 계수 갱신 식에서 고정 스텝 크기에 결정지향 알고리즘의 오차신호의 크기를 곱하여 오차크기에 따라서 스텝 크기가 변하도록 하였다. 또한 결정지향 알고리즘의 오차신호의 크기를 판단하여 어느 임계값 이상에서는 정상상태로의 빠른 수렴 속도를 유지하도록 스텝 크기가 고정인 값을 가지는 MSAG-GMMA가 동작하고, 미만일 때는 스텝 크기가 가변되는 MSAG-GMMA가 동작하도록 하였다. 제안한 알고리즘의 성능을 평가하기 위하여 성능 지수로 앙상블 ISI, 앙상블-평균 MSE, 그리고 등화기의 출력으로 얻어지는 등화 후 신호점도를 사용하였다. 모의실험을 통하여 제안한 알고리즘이 MMA, GMMA, 그리고 MSAG-GMMA보다 빠른 수렴 속도와 정상상태에서 작은 잔류 오차를 가짐을 확인하였다. This paper is concerned with the performance analysis of a modified stop-and-go generalized multi-modulus algorithm (MSAG-GMMA) adaptive blind equalization algorithm with variable step size. The proposed algorithm multiplies the fixed step size by the error signal of the decision-oriented algorithm in the equalization coefficient update equation, and changes the step size according to the error size. Also, the MSAG-GMMA having a fixed step size is operated so as to maintain a fast convergence speed from a certain threshold to a steady state by determining the error signal size of the decision-directed algorithm, and when the MSAG-GMMA to work To evaluate the performance of the proposed algorithm, we use the ensemble ISI, ensemble-averaged MSE, and equalized constellation obtained from the output of the equalizer as the performance index. Simulation results show that the proposed algorithm has faster convergence speeds than MMA, GMMA, and MSAG-GMMA and has a small residual error in steady state.
영어영문학21제26권 2호 : 초등영어 교실에서의 뮤지컬 극화의 활용에 관한 연구
정영화 ( Young Hwa Jeong ),이화자 ( Hwa Ja Lee ) 21세기영어영문학회 2013 영어영문학21 Vol.26 No.2
The purpose of this study is to examine the effects of musicalization on affective development and English proficiency of primary school students. Musicalization was implemented by using key expressions from the textbook and thus English curriculum of the 5th grade was reorganized. For this study, both quantitative and qualitative research data were drawn up. The results of the experiment were analyzed by an independent sample T-test. The findings of this study are as follows: 1) the musicalization activities significantly increased students` interest, self-confidence, and participation towards English learning, 2) English skills were improved through the musicalization lessons, particularly in speaking, 3) the students self-reported positive growth in English proficiency and motivation. The results of this study suggest that the incorporation of musicalization into elementary students` English instruction offer a great benefit to developing their English skills and affective domains.
티타늄 기판 위에 강유전성 BaTiO<sub>3</sub>박막 형성과 분극처리에 의한 Eagle’s MEM 용액에서의 Calcium Phosphate 생성
이용렬,정영화,황규석,송호준,박영준,Lee, Yong-Ryeol,Jeong, Young-Hwa,Hwang, Kyu-Seog,Song, Ho-Jun,Park, Yeong-Joon 한국재료학회 2002 한국재료학회지 Vol.12 No.7
Titanium (Ti) is a bioinert material and has lower elastic coefficient and better strength/volume property than other metals. Ferroelectric materials show alignment of positive and negative charges by poling treatment. This study was purposed to develop a new implant system by combining the advantages of Ti and ferroelectric property of $BaTiO_3$ (BTO). It was performed with the assumption that the $Ca^{2+ }$ ions would be easily attracted on negatively charged surface and the attracted cation might behave as nuclei for bone-like crystal growth in biological solutions. A ferroelectric BTO thin film on Ti was fabricated and the effect of poling treatment on the improvement of calcium phosphate (Ca-P) formation in biological solutions was evaluated. After immersion in Eagle’s minimum essential media (MEM) solution, NaCl was formed on Ti, and Ca-P layer containing NaCl was formed on Ti-O. Weak and sparse Ca-P layers were formed on BTO, while thick, homogeneous, and dense Ca-P layer was formed on negatively polarized BTO (N-BTO), which was confirmed by FE-SEM and EDX. In summary, these results demonstrate that poling the ferroelectric BTO surface negatively is effective for the formation of Ca-P layer in MEM solution, and that N-BTO coating on Ti could be used as a possible alternative method for enhancing the osseointegration of the implants.