http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
YOO, JUHYUN,KIM, DOHYUNG,LEE, YUHYEONG,LEE, ILHA,LEE, SANGHO,KIM, INSUNG,SONG, JAESUNG Taylor Francis 2009 Integrated ferroelectrics Vol.105 No.1
<P> In this study, lead-free 0.95(K0.5Na0.5)NbO3-0.05Li(Sb1 - xNbx)O3 system ceramics were fabricated according to the amount of Nb substitution for Sb site of LiSbO3 ceramics and their dielectric and piezoelectric characteristics were investigated. With increasing the amount of Nb substitution, electromechanical coupling factor (kp), density and piezoelectric constant (d33) increased up to 1mol% Nb and decreased above 1mol% Nb. With increasing the amount of Nb substitution, dielectric constant linearly decreased and Curie temperature increased. At the 1mol% Nb substitution composition ceramics sintered at 1040°C, electromechanical coupling factor (kp), density, dielectric constant (&epsis;r), piezoelectric constant (d33) and Curie temperature (Tc) showed the optimal value of 0.41, 4.35 g/cm3, 789, 206 pC/N and 395°C, respectively for piezoelectric device application.</P>
Juhyun Yoo,Suho Lee,Kabsoo Lee 한국전기전자재료학회 2008 Transactions on Electrical and Electronic Material Vol.9 No.3
In this study, in order to develop the composition ceramics for low loss multilayer piezoelectric actuator application, Pb(Zn₁/₂W₁/₂)O₃-Pb(Mn₁/₃Nb₂/₃)O₃-Pb(Zr,Ti)O₃ (abbreviated as PZW-PMN-PZT)ceramics according to the amount of MnO2 addition were fabricated using two-stage calcinations method. And also, their dielectric and piezoelectric properties were investigated. At the 0.2 wt% MnO₂ added PZW-PMN-PZT ceramics sintered at 930 ˚C, density, electromechanical coupling factor kp, dielectric constant εr, piezoelectric d33 constant and mechanical quality factor Qm showed the optimum value of 7.84 g/cm³, 0.543, 1,392, 318.7 pC/N, 1,536, respectively for low loss multilayer ceramics actuator application.
Juhyun Yoo,Sangmoo Han,Youngkwang Nam,정시영 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.10
In absorption chillers using LiBr aqueous solution, corrosion problems of carbon steel heat exchangers become more serious as the temperature of the generator increases. To reduce the corrosion problems, various surface treatment methods are applied such as a shotpeening. In this study, corrosion characteristics were investigated for untreated and shotpeened surfaces. Pyrex tube samples containing the specimens and LiBr aqueous solution with Li 2 MoO 4 were made and put into a high temperature oven at 200 ℃. After 2000 hours, the surface and cross section of carbon steel specimens were observed using field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDS). It was found that the passive films have the characteristic of a double layer consisting of a thick MoO 2layer and thin Fe 3 O 4 layer. Thicker passive films were observed on the shot-peened surface than the untreated one. As a result of corrosion depth measurement, the shot-peened specimens showed a slightly smaller uniform corrosion depth, however, they showed a much smaller pitting corrosion depth than the untreated ones. It is supposed that the shot-peened surface is more effective in preventing the pitting corrosion than uniform corrosion. The results of this study are expected to be applied effectively to the absorption chillers using LiBr aqueous solution to estimate and reduce the corrosion.
Yoo, Juhyun,Min, Sukkyu,Hwang, Sangmo,Park, Changyub,Yoon, Hyunsang The Korean Institute of Electrical and Electronic 2002 전기전자재료학회논문지 Vol.15 No.4
In this study, $Pb_{0.88}(La_{\alpha}Nd_{1-\alpha})_{0.08}(Mn_{1/3}Sb_{2/3})_{0.02}Ti_{0.98}O_3$ system ceramics with La molar ratio $\alpha$ variation were manufactured for 24 MHz class resonator application. Electromechanical coupling factor, mechanical quality factor and dynamic range of $3^{rd}$ overtone thickness vibration mode were measured as the variations of La and Nd molar ratio. Mechanical quality factor and dynamic range at $\alpha$ = 0.6 composition ceramics showed the highest value of 2691 and 52.37 dB, respectively. The temperature coefficient of resonant frequency measured from $-20^{\circ} to 80^{\circ}$ showed an excellent value of $5ppm/^{\circ}C$ at $\alpha$=1 composition ceramics.
Yoo, Seong Soo,Choi, Gwan H.,Lee, Wooseop,Park, Juhyun,Yi, Gi-Ra,Ryu, Du Yeol,Yoo, Pil J. The Royal Society of Chemistry 2018 SOFT MATTER Vol.14 No.5
<P>Wrinkling is a well-known example of instability-driven surface deformation that occurs when the accumulated compressive stress exceeds the critical value in multilayered systems. A number of studies have investigated the instability conditions and the corresponding mechanisms of wrinkling deformation. Force balance analysis of bilayer systems, in which the thickness of the capping layer is importantly considered, has offered a useful approach for the quantitative understanding of wrinkling. However, it is inappropriate for multilayer wrinkling (layer number > 3) consisting of heterogeneous materials (<I>e.g.</I> polymer/metal or inorganic), in which the thickness variation in the substrate is also crucial. Therefore, to accommodate the additive characteristics of multilayered systems, we thermally treated tri- or quad-layer samples of polymer/metal multilayers to generate surface wrinkles and used a cumulative energy balance analysis to consider the individual contribution of each constituent layer. Unlike the composite layer model, wherein the thickness effect of the capping layer is highly overestimated for heterogenously stacked multilayers, our approach precisely reflects the bending energy contribution of the given multilayer system, with results that match well with experimental values. Furthermore, we demonstrate the feasibility of this approach as a metrological tool for simple and straightforward estimation of the thermomechanical properties of polymers, whereby a delicate change in the Young's modulus of a thin polymeric layer near its glass transition temperature can be successfully monitored.</P>
THE LOW TEMPERATURE SINTERING PROPERTIES OF MODIFIED PbTiO3 CERAMICS
Yoo, Kyungjin,Chung, Kwanghyun,Yoo, Juhyun,Song, Hyunsun Taylor Francis 2007 Integrated ferroelectrics Vol.90 No.1
<P> In the study, in order to develop low-temperature-sintering ceramics for multilayer piezoelectric transformer, (Pb0.76Ca0.24 -xSrx)Ti0.96 (Mn1/3Sb2/3)0.04O3 ceramics were fabricated using Na2CO3 and Li2CO3 as sintering aids and their dielectric and piezoelectric properties were investigated with amount of Sr substitution. The modified PbTiO3 ceramics with a composition of (Pb0.76Ca0.24 - xSrx)Ti0.96 (Mn1/3Sb2/3)0.04O3; x = 0 - 0.05 were prepared by conventional mixed-oxide at sintering temperature of 880, 900 and 930°C. At the sintering temperature of 900°C, thickness vibration mode electromechanical coupling factor (Kt) and thickness vibration mode mechanical quality factor (Qmt) of composition ceramics with 1.0mol% Sr substitution showed the optimal value of 0.50 and 1575 respectively, for multilayer piezoelectric transformer application.</P>
Physical Properties of PNN-PMN-PZT Doped with Zinc Oxide and CLBO for Ultrasonic Transducer
Yoo, Juhyun,Kim, Tahee,Lee, Eunsup,Choi, Nak-Gu,Jeong, Hoy-Seung The Korean Institute of Electrical and Electronic 2017 Transactions on Electrical and Electronic Material Vol.18 No.6
In this paper, to develop the ceramics with high $d_{33}$ and high $Q_m$ for ultrasonic transducer applications, $0.10Pb(Ni_{1/3}Nb_{2/3})O_3-0.07Pb(Mn_{1/3}Nb_{2/3})O_3-0.83Pb(Zr_{0.5}Ti_{0.5})_{0.83}O_3$ (PNN-PMN-PZT) ceramics were sintered at $940^{\circ}C$ using $CuO-Li_2CO_3-Bi_2O_3$ (CLBO) as a sintering aid by a traditional solid-state technique. The influence of zinc oxide additive on the physical properties of the prepared ceramics were systematically investigated. The R-T (rhombohedral-tetragonal) phase coexistence was found in the ceramics without zinc oxide additive and with increasing amounts of ZnO additive, the specimens showed a tetragonal phase. The formation of a liquid phase between ZnO and $Bi_2O_3$ contributed significantly to the grain growth of specimens. For the 0.1 wt% ZnO ceramics, the optimal physical properties of $d_{33}=370pC/N$, ${\varepsilon}_r=1,344$, $k_p=0.621$, and $Q_m=1,523$ were obtained.