• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.178-178
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• 2008

ZnO 바리스터는 인가되는 전압에 따라 저항이 변하는 전압 의존형 저항체이며 각종 전기 전자 정보통신용 제품에 정전기(ESD) 대책용 소자로 폭 넓게 사용되는 전자 세라믹스 부품이다. 특별히 Bi-based ZnO 바리스터는 다양한 상(phase)으로 구성되어 있으며 그 입계의 전기적 특성은 소량 첨가되는 dopant의 종류에 따라 다양하게 변하는 것으로 알려져 있다. 본 연구에서는 Bi-based ZnO 바리스터 (ZnO-$Bi_2O_3$, ZnO-$Bi_2O_3-Mn_3O_4$)에서 각종 유전함수$(Z^*,M^*,\varepsilon^*,Y^*,tan{\delta})$를 이용하여 입계의 주파수-온도에 대한 특성을 살펴 보았다. 일반적인 ZnO 바리스터 제조법으로 시편을 제작하여 78K~800K 온도 범위에서 각종 유전함수를 이용하여 복소 평면도(complex plane plot)와 주파수 응답도(frequency explicit plot)의 방법으로 defect level과 입계 특성(활성화 에너지, 정전용량, 저항, 입계 안정성 등)에 대하여 고찰하였다. ZnO-$Bi_2O_3$(ZB)계와 ZnO-$Bi_2O_3-Mn_3O_4$(ZBM)계 모두 상온 이하의 온도에서 $Zn_i$와 $V_o$의 결함이 나타났으며, 이들의 결함 준위는 각 유전함수에 따라 다소 차이가 났다. 입계 특성으로 ZB계는 이상구간(560~660K)을 전후로 1.15 eV $\rightarrow$ 1.49 eV의 활성화 에너지의 변화가 나타났지만, ZBM계는 이러한 현상이 나타나지 않았다. 또한 입계 전위 장벽의 온도 안정성에 대해서는 Cole-Cole model을 적용하여 분포 파라미터 (distribution parameter; $\alpha$)를 구하여 고찰하였다. ZB계의 입계 안정성은 온도에 따라 불안정해 졌지만, ZBM계는 안정하였다.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.1
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• pp.44-50
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• 2007

In this paper generating algorithms of the conventional chaos code sequences and a new chaos code sequence derived from the real and imaginary parts of FFT of one chaos code sequence, and the time-frequency function characteristics of generated code sequences to measure the signal resolution, are considered. And two chaos based QCSK digital communication systems-one with two different chaos code sequences, the other with FFT of one chaos code sequence-are analyzed in AWGN and fading communication channels. After analyzing the correlation functions of such sequences, the delta-like autocorrelation and near zero crosscorrelation functions of them are very suitable for chaos based spread spectrum communication systems, is verified. Through evaluating the performance of two chaos based QCSK systems above using Monte-Carlo simulation, the improvement of performance in the latter QCSK system compare favorably with that of the former system, is shown.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.4
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• pp.337-345
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• 1991

This study was designed to investigate the effects of dietary protein ana calcium levels on hematological properties and renal functions of the Pb-administered rats. Male Sprague-Dawley rats were assigned to a 3$\times$3$\times$2 factorial design with 3 levels of protein (40％, 16％, 6％), 3 levels of Ca (1.2％, 0.6％, 0.12％) and 2 feeding Periods (3 and 7 Weeks). The Control group was included separately, The rats were exposed to the drinking water containing 2, 000ppm of lead. Hematocrit, hemoglobin content and RBC count were lower in the Pb-added groups than in the control group and were reduced with decreasing dietary protein and Ca levels. Urinary-aminolevulinic acid was higher in the Pb-added groups than in the control group and increased with decreasing dietary Ca level. However, urinary glucose was higher in the Pb-added groups than in the control group and enhanced with decreasing dietary protein and Ca levels. Creatinine celarance was not affected by the Pb administration when the rats fed the diet containing sufficient protein and Ca.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1756-1761
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• 2021

Although the COVID-19 outbreak that occurred in Wuhan, Hubei around December 2019, seemed to be gradually decreasing, it was gradually increasing as of November 2020 and June 2021, and estimated confirmed cases were 192 million worldwide and approximately 184 thousand in South Korea. The Central Disaster and Safety Countermeasures Headquarters have been taking strong countermeasures by implementing level 4 social distancing. However, as the highly infectious COVID-19 variants, such as Delta mutation, have been on the rise, the number of daily confirmed cases in Korea has increased to 1,800. Therefore, the number of cumulative confirmed COVID-19 cases is predicted using ARIMA algorithms to emphasize the severity of COVID-19. In the process, differences are used to remove trends and seasonality, and p, d, and q values are determined and forecasted in ARIMA using MA, AR, autocorrelation functions, and partial autocorrelation functions. Finally, forecast and actual values are compared to evaluate how well it was forecasted.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.213-218
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• 2017

The DC electrolytic capacitor for DC-link of power converter is widely used in various power electronic circuits and system application. Its functions include, DC Bus voltage stabilization, conduction of ripple current due to switching events, voltage smoothing, etc. Unfortunately, DC electrolytic capacitors are some of the weakest components in power electronics converters. Many papers have proposed different algorithms or diagnosis method to determinate the ESR and tan ${\delta}$ capacitance C for fault alarm system of the electrolytic capacitor. However, both ESR vary with frequency and temperature. Accurate knowledge of both parameters at the capacitors operating conditions is essential to achieve the best reference data of fault alarm. According to parameter analysis, the capacitance increases with temperature and the initial ESR decreases. Higher frequencies make the reference ESR with the initial ESRo value to decrease. Analysis results show that the proposed DC Bus electrolytic capacitor reference ESR model setting technique can be applied to advanced reference signal of capacitor diagnosis systems successfully.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.7
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• pp.53-57
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• 2006

PID controller is widely uesd as automatic equipment for industry. However when a system has various characters of intermittence or continuance, a new parameter decision for accurate control is a hard task. As method of solving this problem, in this paper, a Neural Network gain automatic regulator as PID controller functions is presented. A property feedback control gain of system is decided by a rule of Delta learning. The function of proposed automatic Neural Network gain regulator is verified by speed control experiment results of Induction Motor.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.3-10
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• 2013

Please In this paper, to cope with biased impulsive noise problems, a new information potential is proposed that can move the transmitted symbol points by modifying the information potential designed with Dirac-delta functions. Based on the proposed information potential a new blind algorithm is derived by employing an augmented filter structure. From the simulation results in the environment of biased impulsive noise, the conventional algorithms yield performance degradation by over 15 dB, but the proposed algorithm shows no performance degradation and holds the same steady state MSE of below -25 dB as after the initial convergence regardless of the channel conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.519-522
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• 2002

Ag (silver) can be used for YBa$_2$Cu$_3$O$\_$7-$\delta$/(YBCO) coated conductor tape as the substrate on which YBCO can be deposited directly because of the chemical compatibility of Ag with YBCO. We have fabricated rolled Ag tapes with various total reduction ratios and different thicknesses. As-rolled Ag tape was recrystallized at 750$^{\circ}C$ for 30min in air and vacuum of 10$\^$-3/ torr. The orientation distribution functions (ODF) calculated from three x-ray pole figures of as-rolled and recrystallized tapes were analysed. As the total reduction ratio increased from 94 to 98%, the development of {110}texture of as-rolled Ag improved. Under the present experimental condition, maximum {110}ODF value of Ag tape was obtained for the sample with 94% total reduction ratio which was recrystallized at 750$^{\circ}C$ for 30min in vacuum of 10$\^$-3/ torr.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.70.2-70.2
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• 2017

Transit event of exoplanet is a good example of observational studies with youth, because the event is geometrically simple and its analysis is essential to astronomical observation. Therefore, we developed the package of data reduction and aperture photometry in Python for educational purpose. In 27 July, we observed the transit event of TrES-3b with the students of "NYSC Space Science Club" program, and presented the Python package, PyPhotW for data reduction and aperture photometry. PyPhotW consists of simple functions for youth to understand the processes easier. Nonetheless, the photometric results of PyPhotW show a good agreement with those of Source Extractor, ${\Delta}m{\sim}-0.01{\pm}0.03$ and $-0.04{\pm}0.08$ for TrES-3b and TrES-5b time-series observations in 27 - 28 July.

• Journal of Magnetics
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• v.9 no.2
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• pp.27-33
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• 2004

Magnetic properties of $Nd_4Fe_{77.5}B_{18.5}$ compound in term of exchange coupling between $Nd_2Fe_{14}B$ and $Fe_3B$ magnetic nano crystals in melt spun powders were characterized by varying the quenching speed in mass production line. The exchange coupled phenomenon was characterized as functions of nano crystal size and volume fraction of each magnetic phase which was possible by employing Henkel plot (${\delta}M$) and refined Mossbauer spectroscopy. The optimized magnetic properties obtained from the present volume production line were: $B_r= 11.73 kG,{_i}H_c/ = 3.082 kOe$, and $(BH)_{max} = 12.28 MGOe.$ The volume fraction of each magnetic phase for those conditions giving the grain size of 10 nm were ${\alpha}-Fe; 4.2%, Fe_3B; 60.1 %$, and $Nd_2Fe_{14}B; 35.7%$. The superior magnetic properties in the $Nd_2Fe_{14}Fe_3B$ based nanocomposites were confirmed to be dependant on the volume fraction of $Fe_3B$.