• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
• /
• pp.200-201
• /
• 2005

PFerroelectric PZT heterolayered thick films were fabricated by the alkoxide-based sol-gel method. PZT(40/60) and PZT(60/40) paste were made and alternately screen-printed on the $Al_2O_3$ substrates. We have introduced a press-treatment to obtain a good densification of screen printed films. The porosity of the thick films were decreased with increasing the applied pressure and the thick films pressed at 0.6 ton/$cm^2$ showed the dense microstructure and thickness of about 76${\mu}m$. The remanent polarization and coercive field increased with increasing applied pressure and the values for the PZT thick films pressed at 0.6 ton/$cm^2$ were 17.04${\mu}Ccm^2$, 78.09 kV/cm, respectively.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
• /
• pp.309-312
• /
• 2002

Ferroelectric $Sr_{0.3}Ba_{0.7}Nb_{2}O_{6}$ (SBN30) thin films were deposited on Pt/Ti/$SiO_{2}$/Si(100) substrates by ion beam sputtering. During annealing treatment at $750^{\circ}C$, poling was attempted by applying dc voltage bias across polished surfaces. Phase relation, microstructure and crystallization behavior were examined using XRD and FE-SEM. Ferroelectric hysteresis characteristics were also determined where both remanent polarization and coercive values decreased with the increase of bias voltage. The measured remanent polarization and coercive field values at 5 V and 10 V bias were $36{\mu}C/cm^2$, $10{\mu}C/cm^2$ and 100kV /cm, 80kV /cm, respectively.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
• /
• pp.228-229
• /
• 2003

The quasi-phase matching (QPM) technique has dramatically changed the guidelines in developing nonlinear optical materials, which doesn't require birefringence and off-diagonal components for efficient wavelength conversion. Minimum requirement for QPM is the modulation of nonlinearity and ferroelectric materials with low coercive field has become fascinating in periodical poling. Stoichiometric lithium tantalate (SLT) has attractive advantages of low coercive field (∼l .5 KV/mm), high nonlinearity, high optical damage resistance and low thermo-optic coefficients, leading to a large aperture QPM devices for high power operation. (omitted)

• Journal of Magnetics
• /
• 제4권2호
• /
• pp.65-68
• /
• 1999

The M-type barium ferrite ($BaFe_{12}O_{19}$) is well known magnetic material to be used as a permanent magnet due to its strong uniaxial anisotropy. The substitution of nonmagnetic $Ti^{+4}$ and magnetically weak $Co+^2ion for Fe^{+3}$ to its strong uniaxial anisotropy. The substitution of nonmagnetic $Ti^{+4}$ and magnetically weak $Co+^2ion for Fe^{+3}$ sublattices reduces the uniaxial anisotropy and those compounds open a new application field of noise suppressor at high frequencies. In this study, the magnetic and microwave absorbing properties are investigated in Ti-and Co-substituted barium ferrites ($BaFe_{12-2X} Ti_XCo_XO_{19}$). The saturated magnetization decreases linearly with the substitution of Ti and Co. The rapid drop in coercive force is observed with Ti and Co substitution upto x=1.2. The magnetic permeability spectrum shows the natural magnetic resonance in the specimens with small coercive force and large attenuation of microwave is predicted in those specimens at high frequencies (above 4 GHz).

• Journal of Magnetics
• /
• 제2권4호
• /
• pp.130-134
• /
• 1997

The amorphous Co-based alloy Co66Fe4Ni1B15Si14 (Metglas 2714A) is a suitable magnetic core material for high frequency operation. Appreciable reduction of the coercive force can be achieved by proper heat treatment. In this study, samples annealed at wide temperature range were analyzed using differential scanning calorimetry, high frequency B-H loop tester, X-ray diffractometer and resistivity meter. The results show that coercive force at 10 kHz decreases with in-creasing annealing temperature up to 773 K, but dramatically increases above this temperature. The squareness shows that the magnetic anisotropy on longitudinal direction of the as-cast state remains up to 773 K. Above this temperature, it decreases down to 0.5 that represents random distribution of magnetic domains. The crystallization abruptly occurs between 781 K and 783 K.

• 대한가정학회지
• /
• 제34권2호
• /
• pp.57-69
• /
• 1996

The purpose of this study was to probe into the recognitions of mother's role and children behaviors to learn the relationships between mother and child with externalizing behaviors. The subjects were 4 mothers of 4- to 5-year-old externaling children on Korean edition of CBCL. As a way of obtaining more information of mother-child interaction, in-depth interviews were used. The data from interviews were presented in an edited descriptive form. The major findings of this study were as follows : 1) Mothers treated children's wrong behaviors in a coercive manner. 2) It seems that a mother's expectations to be a good mother result in coercive or poor behaviors on externalizing children. 3) Mother had difficulties in handling the children's behaviors and she attributed the reason of wrong behavior to the personality or intention. 4) Mothers seemed to have close relationships with the other than one with externalizing children.

• 마케팅과학연구
• /
• 제18권1호
• /
• pp.81-114
• /
• 2008

The purpose of this study was to analyze how economic factors (economic satisfaction, economic conflict) and non-economic factors (non-economic satisfaction, non-economic conflict) differentially influence Korean retailers' long-term orientation with manufacturers, and how they are influenced by manufacturers' power sources under different levels of retailer dependence. After Korean retailers were divided into high and low dependence groups, path differences between the two groups were compared. The results suggested that manufacturers' coercive and non-coercive power sources do not differentially influence high and low dependence retailers' economic and non-economic satisfaction, and economic and non-economic conflict. However, the economic satisfaction of low dependence retailers more strongly affects their long-term orientation than that of high dependence retailers. Also, the economic conflict of highly dependent retailers more strongly affects their long-term orientation as compared to low dependence retailers. Finally, the impact of non-economic conflict negatively influences a long-term orientation for both retailer groups.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
• /
• pp.83-86
• /
• 1998

Ferroelectric PZT(40/67)/PZT(60/40)heterolayered thin films were Prepared by the alkoxide-based Sol-Gel method. PZT(40/60) and PZT(60/40) stock solutions were made and spin-coated on the P7Ti/Si02/Si substrate alternately. These PZT(40/60) and PZT(60/40) films were dried at 300$^{\circ}C$ for 30min to remove organic materials and were sintered at 650$^{\circ}C$ for 1 hour to crystalize into a perovskite structure. The coating and heating procedure were repeated 6 times to form heterolayered films. Increasing the number of coating, coercive field was decreased. The relative dielectric constant, loss, remanent polarization and coercive field of the 4-coated PZT heterolayered were 1200, 4.1[%], 30.794[${\mu}$C/㎡] and 147.22[kV/cm], respectively.

• Journal of Magnetics
• /
• 제22권1호
• /
• pp.1-6
• /
• 2017

Magnetic properties of CoPt nanoparticles (average size = 2.1 nm) encapsulated in synthesized protein shell have been investigated with SQUID (Superconducting Quantum Interference Device) magnetometer and analyzed by the recently developed non-equilibrium magnetization calculation by our group [T. H. Lee et al., Phys. Rev. B 90, 184411 (2014)]. Field dependence of magnetization measured at 2 K was successfully analyzed with modified Langevin function. In addition, small hysteresis loops having the coercive field of 890 Oe were observed at 2 K. Temperature dependence of magnetization has been measured with zero field cooled (ZFC) and field cooled (FC) protocol with slightly modified sequence in accordance with non-equilibrium magnetization calculation. The analysis on the M vs. T data revealed that the anisotropy energy barrier distribution is found to be very different from the log-normal distribution found in a size distribution. Zero temperature coercive field and Bloch coefficient have also been extracted from the analysis and the validity of those values is checked.

• 한국세라믹학회지
• /
• 제37권1호
• /
• pp.6-11
• /
• 2000

Electron emission from the Pb(ZrxTi1-x)O3 ferroelectrics by pulsed electric field has been investigated as a function of Zr/Ti ratios such as 35/65, 50/50 and 65/35 below 250kV/cm. Electrons were emitted regardless of the applied field polarity to the rear electrode. When the negative field was applied to the rear electrode, the electron emission charge was more stable. It was proved that the electrons were emitted at the edge of the upper electrode. The emission charge increased in order of 65/35>50/50>35/65. The electron emission characteristics were dependent on the ferroelectric properties such as polarization and coercive field. The emission charge and emission threshold field were affected by the polarization change and the coercive field, respectively. This result explains that the electron emission is a field emission with polarization induced surface potential by a modified Fowler-Nordheim plot of emission charge.