• 전기전자학회논문지
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• 제26권2호
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• pp.329-332
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• 2022

본 논문에서는 ferroelectric(HfO₂)구조가 적용된 3D NAND flash memory의 parameter에 따른 lateral charge migration의 retention과 V_th를 분석하였다. P_s가 클수록 Program 시 ferroelectric에서 가능한 최대 polarization이 크기 때문에 초기 V_th는 P_s 25µC/cm² 보다 P_s 70µC/cm²에서 약 1.04V차이로 커진다. 또한 Program 이후 trap된 전자는 시간이 지남에 따라서 lateral charge migration이 발생한다. Program 이후 gate에 전압을 가하지 않고 ferroelectric은 polarization을 유지하기 때문에 P_s와 크게 관계없이 P_r이 클수록 polarization이 커지고 lateral charge migration에 의한 ∆V_th는 P_r 5µC/cm² 보다 P_r 50µC/cm²에서 약 1.54V차이로 작아진다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.289-292
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• 2003

Laboratory tests were performed to investigate the dielectric property of saturated sands contaminated by heavy metals solution at low frequency. Differences of contamination and the real part of dielectric constant depend on heavy metal concentration was measured at low frequency, 100KHz below. The optimal frequency to develop the detection potentials of monitoring was 1KHz, 10KHz, 100KHz. At this frequency, Heavy metal contamination of saturated sands contamination can be recommended by analysis of complex dielectric constant.

• 한국구조물진단유지관리공학회 논문집
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• 제17권4호
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• pp.66-74
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• 2013

본 연구에서는 부동태피막형 무기계 방청제와 흡착형 유기계 방청제를 대상으로, 시멘트세공용액을 모사한 포화 수산화칼슘 수용액내에서 염화물이온 농도와 방청성분 몰비를 변수로 하여 Potentiostat을 사용하여 부식전위, 부식속도, 분극저항을 측정하여 방식성능을 평가하였다. 그 결과, 무기계 방청제는 방청몰비 약 1.2 이상에서 방식성능을 확보하는 것으로 나타났고, 유기계 방청제는 방청몰비 약 0.3 이상에서 방식성능을 확보하는 것으로 나타났다. 또한, 부식속도와 분극저항, 부식속도와 부식전위의 관계는 선형 반비례 경향을 나타냈고, 분극저항과 부식전위는 선형 비례하는 것을 알 수 있었으며, 부식전위, 부식속도, 분극저항과의 상관관계는 유기계와 무기계 방청제에서 큰 차이가 없는 것으로 나타났다.

• The Korean Journal of Ceramics
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• 제1권4호
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• pp.197-203
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• 1995

Nearly fully dense PZT samples both with tetragonal and with morphotropic phase boundary compositions were prepared by the conventional powder processing and sintering. A micro-indentation technique was used to evaluate the dependence of fracture toughness on remanent polarization, crack length and the direction of crack propagation. The result shows that the toughness increases with the remanent polarization along the poling direction and decreases in the transverse direction. The dependence of toughness on the remanent polarization is neither symmetric nor linear but rather shown to be saturated quickly with the increase in remanent polariztion. R-curve behaviors are observed in both poled and unpoled samples. Sequential SEM and XRD studies on annealed, poled, ground, fractured and etched samples show that domain switching is evident as a viable toughening mechanism but might depend upon the rate of crack propagation. Grain bridging is also observed as one of the active toughening mechanisms.

• 한국전기전자재료학회논문지
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• 제17권12호
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• pp.1314-1319
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• 2004

The rosen types of piezo-transformers were prepared and electrical properties were investigated in order to establish the optimum parameters in the process of polarization for ferroelectric materials. Polarization was readily originated with increasing the external energy such as an applied voltage, time, and temperature so that the planar coupling factor and voltage gain were saturated under the conditions of over 14$0^{\circ}C$, applied voltage and time of 4 kV/mm and 3 minutes respectively. The empirical equation for domain rotation probability, which was in proportion to square of an applied voltage and temperature and square root of time, as functions of the above parameters was defined.

• JSTS:Journal of Semiconductor Technology and Science
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• 제9권3호
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• pp.125-135
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• 2009

An analytical 2-dimensional model to explain the small signal and noise properties of an AlGaN/GaN modulation doped field effect transistor has been developed. The model is based on the solution of two-dimensional Poisson's equation. The developed model explains the influence of Noise in ohmic region (Johnson noise or Thermal noise) as well as in saturated region (spontaneous generation of dipole layers in the saturated region). Small signal parameters are obtained and are used to calculate the different noise parameters. All the results have been compared with the experimental data and show an excellent agreement and the validity of our model.

• Journal of Electrical Engineering and Technology
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• 제2권1호
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• pp.98-101
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• 2007

Yttrium(Y)-substituted bismuth titanate $(Bi_{4-x},Y_x)Ti_3O_{12}$ [x=0, 0.25, 0.5, 0.75, 1](BYT) thin films were deposited using an RF sputtering method on the $Pt/TiO_2/SiO_2/Si$ substrates. The structural properties and electrical properties of yttrium-substituted $(Bi_4-xYx)Ti_3O_{12}$ thin films were analyzed. The remanent polarization of $(Bi_4-xYx)Ti_3O_{12}$ films increased with increasing Y-content. The $(Bi_{3.25}Y_{0.75})Ti_3O_{12}$ films fabricated using a top Au electrode showed saturated polarization-electric field(P-E) switching curves with a remanent polarization(Pr) of $8{\mu}C/cm^2$ and coercive field (Ec) of 53 kV/cm at an applied voltage of 7 V. The $(Bi_{3.25}Y_{0.75})Ti_3O_{12}$ films exhibited fatigue-free behavior up to $4.5{\times}10^{11}$ read/write switching cycles at a frequency of 1MHz.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.94-98
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• 2000

Polycrystalline SBTN ferroelectric thin films were prepared by sol-gel method with various Nb mole ratios on Pt/ $SiO_2$/Si (100) substrates. The films were annealed at different temperatures and characterized in terms of phase and microstructure. Relatively a well saturated hysteresis pattern was obtained at x =0.2 in S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$)$_2$ $O_{9+}$$\alpha$/ thin films. At an applied voltage of 5V, the dielectric constant ($\varepsilon$$_{r}$) and dissipation factor (tan $\delta$) of typical S $r_{0.8}$B $i_{2.3}$(T $a_{1-x}$ N $b_{x}$)$_2$ $O_{9+}$$\alpha$/ thin film (x=0.2) were about 236.2 and 0.034. Measured remanent polarization (2Pr) and coercive field (Ec) were 4.28C/c $m_2$, and 38.88kv/cm respectively. No fatigue was observed up to 6$\times$10$_{10}$ switching cycles at 5V and the normalized polarization reduced by a factor of only 4%.%. 4%.%. 4%.%.%.%.%.

• Journal of the Optical Society of Korea
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• 제9권2호
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• pp.59-63
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• 2005

In this paper, we present a novel apodization technique using three beams to fabricate an apodized grating in photopolymer. An orthogonal-polarization beam used to control the saturated modulation amplitude of the grating is added during recording time. As a result of the experiment, holographic apodized gratings with uniform, inverse Gaussian, and triangular profiles are fabricated successfully in DuPont's HRF-150-38 photopolymer.

• 한국터널지하공간학회 논문집
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• 제17권3호
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• pp.383-392
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• 2015

해저터널 건설 중 터널 굴착면 전방에 존재하는 고수압 조건의 함수대 (또는 포화상태의 파쇄대)의 상태를 정확히 예측하는 것은 터널 안전시공의 핵심적인 요소이다. 이 연구는 해저터널 굴착면에서 전방지반의 상태를 예측하기 위해 유도분극(Induced Polarization, IP) 탐사의 활용 가능성을 입증하였다. 모래지반에서의 충전성(chargeability)을 산정하기 위해 간극모델을 제안하고, 충전성과 이에 영향을 미치는 변수들 사이의 관계식을 유도하였다. 관계식을 사용하여 매개변수 분석을 실시하였으며 그 결과 입자 사이의 간극 중 좁은 간극($r_1$)의 크기와 간극수의 염도가 충전성에 가장 큰 영향을 미쳤다. 또한, 실내실험으로 유도분극 현상에 영향을 미치는 지반조건을 파악하기 위해 간극수의 염도와 파쇄대의 두께 변화 그리고 가우지(gouge) 존재 여부에 따른 충전성과 전기비저항의 변화 추이를 규명하고자 하였다. 그 결과 파쇄대의 절리 사이에 가우지가 충진된 경우, 해수조건에서도 충전성이 높게 나타났다. 이는 가우지가 좁은 간극($r_1$)의 크기를 감소시키기 때문이라고 판단된다.