http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
류주현 한국 지리·환경 교육학회 1999 한국지리환경교육학회지 Vol.7 No.1
The use of color for representing geographic data on maps raises many questions. This study addresses questions about which color ensures accurate map reading and which color scheme is suitable for a specific geographic data. Two internal and external experiments and a review of previous color research have been conducted to establish and evaluate criteria for selecting colors to be used to represent geographic data. As a result, color use has proved to be effective in increasing accuracy in map reading. Maps are a unique way of communication and they convey geographic and spatial data. Generally, hue-value color schemes are the most effective method to represent geographic data. Hue-value schemes obviously have the advantages of hue differences and value variation. But I think that common rule is not enough. This study focuses on establishing guidelines which will enable optimal use of colors in map making. Previous research has confirmed the importance of colors, but colors have never been dealt with as an independent factor in map making. I would like to provide these guidelines here: First, map makers should select appropriate color schemes according to the haracteristics of data. For instance, they should select a hue-based scheme for qualitative data and a value-based scheme for the quantitative data. Second, quantitative data can be divided into three groups. Therefor, different schemes should be applied according to the characteristics of quantitative data. Third, the type of map task or the correlation between geograhic data and space is also a major factor in selecting color schemes. For instance, hue-based scheme is the most suitable to provide individual regional geographic data. Value-based scheme is the most suitable to provide the general trend of map. And the color scheme is influenced by direct acquisition task or recall task Forth, the education level of map users should be considered in map making. Specially numbers of data classes. Research on color symbolization is important in that computer mapping software is now widely available. Guidelines should be provided to improve the design of customized color schemes. Appropriate use of color schemes can improve the effectiveness of maps, improved color schemes will help map makers, including geography teachers, to gain insights into data.
류주현,서성재,Ryu, Ju-Hyeon,Seo, Seong-Jae The Korean Institute of Electrical Engineers 1999 전기학회논문지C Vol.48 No.9
Piezoelectric properties of PMN-PZT ceramics with $CeO_2$ impurity were investigated. Mechanical quality factor, $Q_m$ of 1792, 1285 and the electromechanical coupling coefficient, $k_p$ of 0.52, 0.54 were obtained from the specimen with 0.25 and 0.5 mole % $CeO_2$ respectively. Curie temperature was decreased with the addition of $CeO_2$ while the electric coercive field was proportional to the amount of impurity. Based on the system ceramics with 0.5 mole % cerium oxide, a Rosen type piezoelectric transformer was fabricated and tested. Voltage step-up ratios of 230 and 13 were obtained from the transformer at no load and $100 k\Omega$ resistance, respectively. Experimental results showed a potential of the transformer for the practical use coupled with the expected strength increase by the grain size refinement.
저온소결 PMN-PNN-PZT 세라믹스를 이용한 고출력 강압용 적층 압전변압기의 전기적 특성
류주현,김국진,백동수,윤현상,Yoo, Ju-Hyun,Kim, Kook-Jin,Paik, Dong-Soo,Yoon, Hyun-Sang 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.4
In this study, multilayer piezoelectric transformer was manufactured using the PMN-PNN-PZT ceramic and then the electrical characteristics were investigated according to the variations of frequency and load resistance. The voltage step-up ratio of multilayer piezoelectric transformer showed the maximum value at the vicinity of 75 kHz and increased according to the increase of load resistance. When the output impedance coincided with the load resistance, the multilayer piezoelectric transformer showed the temperature rise of less than $20^{\circ}C$ at the output power of 20 W. As the results, the multilayer piezoelectric transformer manufactured at low co-firing temperature of $940^{\circ}C$ using PMN-PNN-PZT ceramics could be stably driven as the step-down transformers.
PNW 치환에 따른 PSN-PZT 세라믹스의 미세구조 및 압전특성
류주현,우원희,오동언,류성림 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.10
In this study, microstructure and piezoelectric properties of PSN-PZT ceramics modified with BiFeO$_3$ were investigated as a function of PNW substitution. With the increase of PNW substitution, tetragonality, Curie temperature and mechanical quality factor were decreased but grain size and electromechanical coupling factor(kp) was gradually increased. At 4 mol[%] PNW substitution, maximum kp of 0.567 was obtained.
저온소결한 PSN-PZT 세라믹스의 Zr/Ti 비에 따른 압전특성
류주현,우원희,오동언,정영호,정광현,류성림 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.12
In this study, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, dielectric and piezoelectric properties of PSN-PZT[0.91Pb(Sb$\sub$1/2/Nb$\sub$1/2/)$\sub$0.03/(Zr$\sub$0.495/Ti$\sub$0.505/)$\sub$0.97/O$_3$-0.04Pb(Ni$\sub$1/2/W$\sub$1/2/)O$_3$+0.05BiFeO$_3$+0.3wt%MnO$_2$+0.6wt%CuO〕 ceramics were investigated according to Zr/Ti ratio. As Zr/Ti ratio is increased, electromechanical coupling factor(k$\sub$p/) and dielectric constant increased and then decreased after the ratio of Zr/Ti=50/50. Also, mechanical qualify factor(Q$\sub$m/) decreased and then increased after the ratio of Zr/Ti=50/50.
무연 (Na<sub>1</sub>,K)NbO<sub>3</sub> 계 세라믹스를 이용한 AE센서의 감도특성
류주현,이갑수,홍재일,Yoo, Ju-Hyun,Lee, Gab-Soo,Hong, Jae-Il 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.3
In this study, Acoustic emission(AE) sensors were fabricated using lead-free piezoelectric ceramics for prohibiting environmental pollution. Structure of AE sensors were designed as Langvin type air backing form. Here, the piezoelectic element was used as PZT(EC-65)(AE1) and NKN(AE2), respectively. The measured resonant frequency, the maximum sensitivity frequency and sensitivity of AE sensors were as follows ; 143 kHz, 29.4 kHz and 69.3 dB in AE1 and 179 kHz, 29.4 kHz and 66.3dB in AE2, respectively.
PDA CCFL 구동을 위한 압전트랜스포머 용 PNW-PMN-PZT 세라믹스의 Nb<sub>2</sub>O<sub>5</sub> 첨가에 따른 미세구조 및 압전특성
류주현,황락훈,김철희,오동언,장은성,정영호,홍재일 한국전기전자재료학회 2004 전기전자재료학회논문지 Vol.17 No.3
PNW-PMN-PZT ceramics were fabricated with the variations of Nb$_2$O$_{5}$ addition and their microstructural and piezoelectric characteristics were investigated. When the amount of Nb$_2$O$_{5}$ increased, grain size decreased gradually. At 0.3wt% Nb$_2$O$_{5}$ which is the same weight percent with Fe$_2$O$_3$, maximum tetragonality(c/a) and density were shown due to the complexed doping effects. Also, this composition that showed Qm of 2,041, kp of 0.55, grain size of 2.5${\mu}{\textrm}{m}$ and $\varepsilon$r of 1704 were proper for high power application. Using this composition, Rosen-type piezoelectric transformer was fabricated as the size of 1 ${\times}$ 16 ${\times}$ 5㎣ and its electrical characteristics were investigated with the variations of load resistance and driving frequency. At the resistance of 200㏀, maximum step-up ratio of 13.68 was shown. After driving PDA CCFL for 25 min using the inverter circuit, at driving frequency of 214.4KHz, input voltage of 31.78 V and input current of 21.1mA were measured at the input part of piezoelectric transformer. And then, output voltage of 293.2 V and output current of 2.2mA were shown at the output part of piezoelectric transformer. At the same time, efficiency of 96.2% and temperature rise of 3.5$^{\circ}C$ were appeared at the piezoelectric transformer.ormer.