• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.418-429
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• 2011

Novel chromium(III), manganese(II), iron(III), cobalt(II), nickel(II), copper(II), ruthenium(III), and zirconyl(II) complexes of $N^1,N^2$-bis(3-((3-hydroxynaphthalen-2-yl)methylene-amino)propyl)phthalamide ($H_4L$, 1) have been synthesized and characterized by elemental, physical, and spectral analyses. The spectral data showed that the ligand behaves as either neutral tridentate ligand as in complexes 2-5 with the general formula $[H_4LMX_2(H_2O)]{\cdot}nH_2O$ (M=Cu(II), Ni(II), Co(II), X = Cl or $NO_3$), neutral hexadentate ligand as in complexes 10-12 with the general formula $[H_4LM_2Cl_6]{\cdot}nH_2O$ (M=Fe(III), Cr(III) or Ru(III)), or dibasic hexadentate ligand as in complexes 6-9 with the general formula $[H_2LM_2Cl_2(H_2O)_4]{\cdot}nH_2O$ (M = Cu(II), Ni(II), Co(II) or Mn(II), and 13 with general formula $[H_4L(ZrO)_2Cl_2]{\cdot}8H_2O$. Molar conductance in DMF solution indicated the non-ionic nature of the complexes. The ESR spectra of solid copper(II) complexes 2, 5, and 6 showed $g_{\parallel}$ >g> $g_e$, indicating distorted octahedral structure and the presence of the unpaired electron in the $N^1,N^2$ orbital with significant covalent bond character. For the dimeric copper(II) complex $[H_2LCu_2Cl_2(H_2O)_4]{\cdot}3H_2O$ (6), the distance between the two copper centers was calculated using field zero splitting parameter for the parallel component that was estimated from the ESR spectrum. The antibacterial and antifungal activities of the compounds showed that, some of metal complexes exhibited a greater inhibitory effect than standard drug as tetracycline (bacteria) and Amphotricene B (fungi).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.3
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• pp.160-164
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• 2015

In this study, $(1-x)Pb(Mg_{1/2}W_{1/2})_{0.03}(Ni_{1/3}Nb_{2/3})_{0.09}(Zr_{0.5}Ti_{0.5})_{0.88}O_3+xCeMnO_3$ (x= 0~0.02) ceramics were prepared by Columbite precursor method. The phase structure, ferroelectric and piezoelectric properties were systematically investigated. It was found that PMW-PNN-PZT possessed superior electrical properties due to its composition close to the MPB (morphotropic phase boundary). Coercive electric field of 10.05 [kV/cm] and density of 7.88 [$g/cm^3$] were obtained when the substitution amount of $CeMnO_3$ is x=0.02. In contrast, specimens with x=0.01 showed the mechanical quality factor($Q_m$) of 1,091 and the electromechanical coupling factor($k_p$) of 0.613.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.253-253
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• 2007

압전 액츄에이터 및 초음파진동자의 응용범위가 넒어짐에 따라 변위량, 응력 등을 개선시키기 위해 전기기계결합계수 kp 및 압전 d상수가 종전보다 큰 재료가 요구되고 있으며, 초음파진동자나 압전 모터와 같이 마찰에 의한 열손실이 많이 발생하는 액츄에이터에 적용할 큰 기계적품질계수롤 가지는 저손실 압전 액츄에이터 및 초음파진동자용 재료가 필요한 실정이다. PZT계 세라믹스는 높은 유전상수와 압전특성으로 전자세라믹스분야에서 가장 널리 사용되어지고 있지만, $1200^{\circ}C$이상의 높은 소결온도 때문에 $1000^{\circ}C$ 부근에서 급격히 휘발되는 PbO로 인한 환경오염과 기본조성의 변화로 인한 압전특성의 저하가 문제시 되고 있다. $Pb(Ni_{1/3}Nb_{2/3})O_3$는 약 $-120^{\circ}C$정도의 큐리온도룰 가지는 강유전체로 Pb(Zr, Ti)$O_3$계 세라믹스에 치환 시 유전상수와 전기기계결합계수를 개선시키는 대표적인 성분이다. 따라서 본 연구에서는 저온소결 저손실의 적층형 압전 액츄에이터를 개발하기 위해 PMS-PMN-PZT계 세라믹스에 $Pb(Ni_{1/3}Nb_{2/3})O_3$ 세라믹스를 치환하고 $Li_2CO_3$와 $Na_2CO_3$ ZnO를 소결조재로 사용하여 저온소결 하였으며 PNN 치환량에 따른 결과를 관찰 하였다.

• Journal of the Korean Electrochemical Society
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• v.10 no.4
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• pp.283-287
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• 2007

KIER has been developing the anode-supported flat tubular solid oxide fuel cell unit bundle for the intermediate temperature($700{\sim}800^{\circ}C$) operation. Anode-supported flat tubular cells have Ni/YSZ cermet anode support, 8 moi.% $Y_2O_3$ stabilized $ZrO_2(YSZ)$ thin electrolyte, and cathode multi-layer composed of Sr-doped $LaSrMnO_3(LSM)$, LSM-YSZ composite, and $LaSrCoFeO_3(LSCF)$. The prepared anode-supported flat tubular cell was joined with ferritic stainless steel cap by induction brazing process. Current collection for the cathode was achieved by winding Ag wire and $La_{0.6}Sr_{0.4}CoO_3(LSCo)$ paste, while current collection for the anode was achieved by using Ni wire and felt. For making stack, the prepared anode-supported flat tubular cells with effective electrode area of $90\;cm^2$ connected in series with 12 unit bundles, in which unit bundle consists of two cells connected in parallel. The performance of unit bundle in 3% humidified $H_2$ and air at $800^{\circ}C$ shows maximum power density of $0.39\;W/cm^2$ (@ 0.7V). Through these experiments, we obtained basic technology of the anode-supported flat tubular cell and established the proprietary concept of the anode-supported flat tubular cell unit bundle.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1368-1369
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• 2006

In this thesis, the minuteness structure, piezoelectric, and dielectric characteristics of Pb[(Co0.5 W0.5) 0.03 (Ni1/3 Nb2/3) 0.07(Zr0.52 Ti0.48)0.9]O3+0.5Wt% MnO2 ceramics has been systematically investigated as a function of the sintering temperature after manufacturing the specimens with a general method. The electromechanical coupling coefficient (Kp) showed its maximum of 31.116[%] in the sintered specimens at $1050[^{\circ}C]$, and its minimum of 20.220[%] in the sintered specimens at $1150[^{\circ}C]$. The mechanical quality coefficient (Qm) marked the maximum of 139.526 at the sintering temperature of $1150[^{\circ}C]$.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.208-208
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• 2003

저온균일침전법(HPPLT)으로 제조된 TiO$_2$나노분말은 10$0^{\circ}C$이하의 온도에서 rutile상을 얻을 수 있다. 또한, rutile에서 anatase로의 상변화는 합성시간, 가열속도, 반응온도 그리고 음이온 첨가에 의해 일어난다고 보고되어졌지만, 금속양이온들에 의한 상변화는 알려진 바가 없다. 따라서, 다양한 양이온을 첨가하여 저온균일침전법에서 TiO$_2$의 상변화가 어떻게 일어나는지를 조사하였다. 출발원료인 TIC1$_4$를 사용하여 가수분해하여 0.67M의 TiOCl$_2$을 얻었다. 얻어진 TiOCl$_2$ 수용액에 각각 0.01M의 금속염화물(ZrOCl$_2$, NiCl$_2$, CuCl$_2$, FeCl$_3$, AlCl$_3$ 그리고 NbCl$_{5}$)을 첨가한 후 반응기에 넣고 10$0^{\circ}C$에서 4시간동안 가열하였다 가열한 후 얻어진 침전물에 NaOH 수용액을 이용하여 PH 7-8로 중화한 후 증류수로 Cl$^{-}$이온이 제거될 때까지 충분히 세척하였다. 세척된 침전물을 105$^{\circ}C$에서 24h동안 건조하여 분말을 얻었고, rutile에서 anatase로의 상변화특성을 관찰하기 위하여 XRD, SEM, TEM, ICP 분석을 실시하였다.

• Journal of environmental and Sanitary engineering
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• v.9 no.2
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• pp.8-23
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• 1994

During the period from Mar., 1991 to Feb., 1992 66 tSP samples were collected by Hi volume air sampler at 1 sampling site in Seoul and the amount of concentration of 21 components(SO$_{4}$$^{2-}$, NO$_{3}$$^{-}$, NH$_{4}$$^{+}$, Cl$^{-}$, Al, Ba, Ca, Cd, Cr, Cu, Fe, It Mg, Mn, Na, Ni, Pt Si, Ti, Zn, Zr ) were measured. And monthly and seasonal variation were surveyed and the principal component analysis( PCA ) were carried out with respect to these amount of pollutants, minimum of visibility and radiation on a horizontal surface. The total amount of soluble ion in water was high in order o(SO$_{4}$$^{2-}$> NO$_{3}$$^{-}$> N%'>Cl$^{-}$ and metal ion was high in order of Na> Ca>Si> Fe> Al> K> Mg> Zn> Pb> Cu>Ti> Mn > Ba> Cr> Zr> Ni> Cd. There was Seasonal variation in concentration for SO$_{4}$$^{2-}$, NH$_{4}$$^{+}$, Cl$^{-}$, Na, Al, Ca, Bt Mg, Fe and Si. It was assumed that the components of the highest concentration on April were depend on yellow sand and the frequency of wind velocity and direction. As the results of PCA, the amount of pollution components was able to characterized with two principal components(Z$_{1}$, Z$_{2}$ ). The first principal components Z$_{1}$ was considered to be a factor indicating the pollutants originated from natural generation and The second principal components Z$_{2}$ was considered to be a factor indicating the pollutants originated from human work. The monthly concentration of pollutants in ISP, minimum of visibility and radiation on a horizontal surface was possible to evaluate by the use of these two principal components Z$_{1}$ and Z$_{2}$ .

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.9
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• pp.766-770
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• 2007

In this study, in order to develop low temperature sintering ceramics for multilayer piezoelectric actuator, $0.07Pb(Mn_{1/3}Nb_{2/3})O_3-xPb(Ni_{1/3}Nb_{2/3})O_3-(0.93-x)Pb(Zr,Ti)O_3$ ceramics system were fabricated using $Li_2CO_3-Bi_2O_3-CuO$ sintering aids and the specimens were sintered at $930^{\circ}C$. Thereafter, their piezoelectric and dielectric characteristics were investigated according to the amount of PNN substitution. At 9 mol% PNN substitution, density, electromechanical coupling factor ($k_p$), dielectric constant, mechanical quality factor ($Q_m$) and piezoelectric constant ($d_{33}$) showed the optimum value of $7.86g/cm^3$, 0.60, 1640, 1323 and 387 pC/N, respectively. It is considered that these values are suitable for piezoelectric divece application such ad multilayer piezoelectric actuator and ultrasonic vibrator with pure Ag internal electrode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.12
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• pp.1077-1082
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• 2008

To fabricate a multi-layered piezoelectrics/electrodes structure, the piezoelectrics should be sintered at the temperature lower than $950^{\circ}C$ to use the silver electrode, which is cheaper than the electrodes containing noble metals such as Pd and Pt. Therefore, in this study, we modified the composition of $Pb(Zr,Ti)O_3$-based material as $(Pb_{0.98}Cd_{0.02})(Ni_{1/3}Nb_{2/3})_{0.25}Zr_{0.35}Ti_{0.4}O_3$ to lower the sintering temperature and to improve the piezoelectric properties. Small amount of $MnCO_3$, $SiO_2$, and $Pb_3O_4$ were also added to lower the sintering temperature of the ceramic. The prepared raw powders were mixed by using a ball mill for 24 hours. And then the mixed powders were calcinated for 2 hours at $800^{\circ}C$. The calcinated powders were again crushed with the ball mill for 72 hours. The final powders were pressed for making the shape of ${\emptyset}15\;mm$ disk. The disk-type samples were sintered at temperature range of $850{\sim}950^{\circ}C$. The crystal phases of the sintered specimens were perovskite structure without secondary phases. All of the measured electrical properties such as electromechanical coupling coefficients ($k_p$), mechanical quality factors ($Q_m$), and piezoelectric charge constants ($d_{33}$) were decreased with decreasing the sintering temperatures. The electrical properties measured at the sample sintered at $950^{\circ}C$ were 54% of $k_p$, 503 of $Q_m$, and 390 pC/N of $d_{33}$, respectively. These properties were considered to be fairly good for the application of multi-layered piezoelectric generators or actuators.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.5
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• pp.450-457
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• 2009

Periodical thermal shock can introduce defects in thermal barrier coating made by layers of CoNiCrAlY bond coating(BC) and $ZrO_2-8wt%Y_2O_3$ ceramic top coating(TC) on Inconel-738 substrate using plasma spraying. Thermal shock test is performed by severe condition that is to heat until $1000^{\circ}C$ and cool until $20^{\circ}C$. As the number of cycle is increased, the fatigue by thermal shock is also increased. After test, the micro-structures and mechanical characteristics of thermal barrier coating were investigated by SEM, XRD. The TGO layer of $Al_2O_3$ is formed between BC and TC by periodical thermal shock test, and its change in thickness is inspected by eddy current test(ECT). By ECT test, it is shown that TGO and micro-crack can be detected and it is possible to predict the life of thermal barrier coating.