• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.3
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• pp.157-160
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• 2002

The ferroelectric domain variation and electrical performance of $Pb(Zr,Ti)O_{3}$ (PZT) based capacitors through La additions were systematically studied. La substitution up to 10 % was performed to lower the coercive and saturation voltages of epitaxial ferroelectric capacitors grown on Si using a (Ti_{0.9}Al_{0.1})N/Pt$ conducting barrier composite. Ferroelectric capacitors substituted with 10 % La show significantly lower coercive voltage compared to capacitors with 0 % and 3 % La. This is attributed to a systematic microstructure change into $180^{\circ}C$ domain and decrease in the tetragonality (i.e., c/a ratio) of the ferroelectric phase. These capacitors show promise as storage elements in low power memory architectures.

• Journal of the Korean Ceramic Society
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• v.31 no.4
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• pp.381-388
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• 1994

A new process which co-fires the low-firing-substrate and copper conductor was studied to achieve good bond strength and low sheet resistance of conductor. Cupric oxide is used as the precursor of conductive material in the new method and the firing atmosphere of the new process is changed sequently in air H2N2. The addition of cupric oxide and variations of firing atmosphere permited complete binder-burnout in comparison with the conventional method and contributed to the improvement of resistance and bonding behaviors. The potimum conditions of this experiment to obtain the satisfactory resistance and bond strength are as follows (binder-burnout temperature in air; 55$0^{\circ}C$, reducing temperature in H2; 40$0^{\circ}C$ for 30 min, ratio of copper and cupric oxide; 60:40~30:70 wt%). The bonding mechanism between the substrate and metal was explained by metal diffusion layer in the interface and the bond strength mainly depended on the stress caused by the difference of shrinkage and thermal expansion coefficient between the substrate and metal.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.244-247
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• 1999

The(Sr$\sub$0.85/Ca$\sub$0.15/) TiO$_3$(SCT) thin films are deposited on Pt-coated electrode(Pt/TiN/SiO$_2$/Si) using RF sputtering method. The composition of SCT thin films deposited on Si substrate at room temperature is close to stoichiometry(1.102 in A/B ratio). Also, SCT thin films deposited on Pt-coated electrodes have the cubic perovskite structure and polycrystalline state. The maximum dielectric constant of SCT thin films is obtained by annealing at 600[$^{\circ}C$].The dielectric constant changes almost linearly in temperature ranges of -80~+90[$^{\circ}C$].

• Journal of the Korean Society for Precision Engineering
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• v.7 no.2
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• pp.105-112
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• 1990

Advanced ceramics have some excellent properities as the material for the mechanical component. It is, however, very difficult to grind ceramics with high efficiency because of their high strength, hardness and brittleness. In this paper, some experiments are carried out to find the basic grinding characteristic of advanced ceramics. Representative advanced ceramics, such as AL/sub 2/ O/sub 3/, ZrO/sub 2/, SiC and Si/sub 3/N/sub 4/and ground with diamond wheels. Special attention is paid to comparison between the conventional and creep feed grinding. Results obtained in this study provide some useful informations to attain the high efficiency grinding of advanced ceramics.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.42-51
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• 2004

Peat humin(p-Humin), humic acid(p-HA) and fulvic acid(p-FA) were isolated from Canadian Sphagnum peat moss by dissolution in 0.1M NaOH followed by acid precipitation. After purification cycles, they are characterized for their elemental compositions and, acid/base properties. Functionalities and carbon structures of the humic fractions were also characterized using FT-IR and solid state $^{13}C$-NMR spectroscopy. Those results are compared with one another and with soil humic substances from literatures. Main purpose of this study was to present a chemical and spectroscopic characterization data of humic substance from peat moss needed to evaluate its environmental applicability. The relative proportions of the p-Humin, p-HA and p-FA in the peat moss was $76\%,\;18\%,\;and\;3\%$, respectively, based on the total organic matter content ($957{\pm}32\;g/kg$). Elemental composition of p-Humin were found to be $C_{1.00}H_{1.52}O_{0.79}N_{0.01}$ and had higher H/C and (N+O)/C ratio compared to those of p-HA($C_{1.00}H_{1.09}O_{0.51}N_{0.02}$) and p-FA($C_{1.00}H_{1.08}O_{0.65}N_{0.01}$). Based on the analysis of pH titration data, there are two different types of acidic functional groups in the peat moss and its humic fractions and their proton exchange capacities(PEC, meq/g) were in the order p-FA(4.91) >p-HA(4.09) >p-Humin(2.38). IR spectroscopic results showed that the functionalities of the peat moss humic molecules are similar to those of soil humic substances, and carboxylic acid(-COOH) is main function group providing metal binding sites for Cd(II) sorption. Spectral features obtained from $^{13}C$-NMR indicated that peat moss humic molecules have rather lower degree of humification, and that important structural differences exist between p-Humin and soluble humic fractions(p-HA and p-FA).

• Clean Technology
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• v.27 no.1
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• pp.9-16
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• 2021

Since the active matrix organic light-emitting diode (AMOLED) encapsulation process is very vulnerable to moisture and oxygen, high-purity nitrogen with minimal moisture and oxygen must be used. In this study, a copper-based catalyst used to remove oxygen from nitrogen in the AMOLED encapsulation process was optimized. Two-component and three-component catalysts composed of CuO, Al2O3, or ZnO were prepared through a co-precipitation method. The prepared catalysts were characterized by using BET, XRD, TPR, and XRF analysis. In order to verify the oxygen removal performance of the catalyst, several catalytic reactions were conducted in a fixed bed reactor, and the corresponding oxygen contents were measured through an oxygen analyzer. In addition, reusability of the catalysts was proven through repetitive regeneration. The properties and oxygen removal capacity of the catalysts prepared with CuO and Al2O3 ratios of 6 : 4, 7 : 3, and 8 : 2 were compared. The number of active sites of the catalyst with a ratio of CuO and Al2O3 of 8 : 2 was the highest among the 2-component catalysts. Moreover, the reducibility of the catalyst with a ratio of CuO and Al2O3 of 8 : 2 was the best as it had the highest CuO dispersion. As a result, the oxygen removal ability of the catalyst with a ratio of CuO and Al2O3 of 8 : 2 was the best among the 2-component catalysts. The best oxygen removal capacity was obtained when 2wt% of ZnO was added to the sub-optimized catalyst (i.e., CuO : Al2O3 = 8 : 2) probably due to its outstanding reducibility. Furthermore, the optimized catalyst kept its performance during a couple of regeneration tests.

• Membrane Journal
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• v.28 no.4
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• pp.221-232
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• 2018

The silica containing carbon ($C-SiO_2$) membranes were fabricated using poly(imide siloxane)(Si-PI) and polyvinylpyrrolidone (PVP) blended polymer. The characteristics of porous carbon structures prepared by the pyrolysis of polymer blends were related with the micro-phase separation behaviors of the two polymers. The glass transition temperatures ($T_g$) of the mixed polymer blends of Si-PI and PVP were observed with a single $T_g$ using differential scanning calorimetry. Furthermore, the nitrogen adsorption isotherms of the $C-SiO_2$ membranes were investigated to define the characteristics of porous carbon structures. The $C-SiO_2$ membranes derived from Si-PI/PVP showed the type IV isotherm and possessed the hysteresis loop, which was associated with the mesoporous carbon structures. For the molecular sieving probe, the $C-SiO_2$ membranes were prepared with the ratio of Si-PI/PVP and the pyrolysis conditions, such as the pyrolysis temperature and the isothermal times. Consequently, the $C-SiO_2$ membranes prepared by the pyrolysis of Si-PI/PVP at $550^{\circ}C$ with the isothermal time of 120 min showed the $O_2$ permeability of 820 Barrer ($1{\times}10^{-10}cm^3(STP)cm/cm^2{\cdot}s{\cdot}cmHg$) and $O_2/N_2$ selectivity of 14.

• Journal of the Korean Magnetics Society
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• v.9 no.2
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• pp.78-84
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• 1999

$(Ni, Zn)Fe_2O_4$ powders were prepared through self-propagating high temperature synthesis reaction and the effects of initial zinc oxide powder size and oxygen pressure on the magnetic properties of the final combustion products were studied. The ferrite powders were combustion synthesized with iron, iron oxide, nickel oxide, and zinc oxide powders under various oxygen pressures of 0.5~10 atmosphere after blended in n-hexane solution for 5 minutes with a spex mill, followed by dried at 120 $^{\circ}C$ in vacuum for 24 hours. The maximum combustion temperature and propagating rate were about 1250 $^{\circ}C$ and 9.8 mm/sec under the tap density, which were decreased with decreasing ZnO size and oxygen pressure. The final product had porous microstructure with spinel peaks in X-ray spectra. As the ZnO particle size in the reactant powders and oxygen pressure during the combustion reaction increase, coercive force, maximum magnetization, residual magnetization, squareness ratio were changed from 1324 Oe, 43.88 emu/g, 1.27 emu/g, 0.00034 emu/gOe, 37.8$^{\circ}C$ to 11.83 Oe, 68.87 emu/g, 1.23 emu/g, 0.00280 emu/gOe, 43.9 $^{\circ}C$ and 7.99 Oe, 75.84 emu/g, 0.791 emu/g, 0.001937 emu/gOe, 53.8 $^{\circ}C$ respectively. Considering the apparent activation energy changes with oxygen pressure, the combustion reaction significantly depended on initial oxygen pressure and ZnO particle size.

• Journal of Bio-Environment Control
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• v.20 no.3
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• pp.227-232
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• 2011

The processing techniques are need to use the non-marketable paprika fruit because paprika that is difficult crop for cultivation and produced easily non-marketable fruits, such as physiological disorder fruit, malformed fruit, and small size fruit. This study was carried out to investigate the proper active modified atmosphere packaging (MAP) condition for enhancing the storability of fresh-cut paprika fruit. The fresh-cut paprika (cv 'Score', seminis) put into $7cm{\times}0.7cm$ size and packed them in 20 g bags. The active MAP and vacuum treated paprika fruits were packaged with LLDPE/Nylon, EVOH, Tie film, and injected partial pressures of $CO_2$ and $O_2$, and $N_2$ in the packages immediately after sealing to treat active MAP. The ratio of $CO_2$, $O_2$, and $N_2$ of active MAP conditions were 0 : 20 : 80 (air), 5 : 5 : 90, 30 : 10 : 60, 10 : 70 : 20 and vacuum treatment did not contain any gas. The passive packaging treated paprika packaged with $40{\mu}m$ ceramic film. After 7 days of storage at $9^{\circ}C$, the fresh weight decreased less than 2% in all treatments, and showed lower in 5 : 5 : 90 ($CO_2:O_2:N_2$) active-MAP treatment and higher in vacuum treatment than other treatments. The $CO_2$ and $O_2$ concentration in packages did not change remarkably in active-MA treatments except 30 : 10 : 60 active-MAP treatment that showed sharply decreased $O_2$, concentration and increased $CO_2$ concentration at $1^{st}$ day of storage at $9^{\circ}C$. The ethylene concentration in package was the highest in 30 : 10 : 60 active-MAP treatment and the lowest in the passive MAP treatment that packaged with gas permeable film during $9^{\circ}C$ storage for 7 days. The 30 : 10 : 60 active-MAP treatments were not proper condition to storage fresh-cut paprika. The visual quality was maintained higher in 0 : 20 : 80 (air), 5 : 5 : 90, and 10 : 70 : 20 active MAP treatments and passive MAP treatment than others and the firmness, off-odor, and electrolyte leakage was investigated at 7th day of storage at $9^{\circ}C$. The 5 : 5 : 90 and 10 : 70 : 20 active-MAP treatment showed higher firmness and lower off-odor than other treatments after $7^{th}$ day of storage at $9^{\circ}C$. In addition, the electrolyte leakage was reduced less than 20% at 0 : 20 : 80 (air), 5 : 5 : 90, 10 : 70 : 20, and passive MA treatments. Therefore, 10 : 70 : 20 ($CO_2:O_2:N_2$) and 0 : 20 : 80 (air) might be recommended for proper active MAP conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.317-321
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• 2002

Piezoelectric properties of $(Pb_{1-x}Y_x)[(Ni_{1/3}Nb_{2/3})_{0.15}(Zr_{1/2}Ti_{1/2)})_{0.85}]O_{3}$ (x=0~0.05) ceramics were investigated, The stoichiometric PNN-PZT ceramics required the sintering temperature above $1100^{\circ}C$, but the addition of $Y_{2}O_{3}$ in the PNN-PZT ceramic lowered the sintering temperature down to $1000^{\circ}C$. In case of x=0.005, the electro-mechanical coupling $factor(K_p)$, the piezoelectric $constant(d_{33})$, and the maximum strain ratio of PNN-PZT ceramics sintered at $1000^{\circ}C$ were 53.1%, 395pC/N, and $2200{\times}10^{-6}$ respectively, A 30-layer piezoelectric actuator$(10{\times}10{\times}1.7mm)$ fabricated with the above material showed the maximum strain of $2.09{\mu}m$ under 100V DC bias.