• Journal of Electrochemical Science and Technology
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• 제13권3호
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• pp.369-376
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• 2022

In this study, the stability of an anion exchange membrane water electrolyzer (AEMWE) cell was evaluated in an on-off cycling operation with respect to an applied electric bias, i.e., a current density of 500 mA cm^-2, and an open circuit. The ohmic and polarization resistances of the system were monitored during operation (~800 h) using electrochemical impedance spectra. Specific consideration was given to the ohmic resistance of the cell, especially that of the membrane under on-off cycling conditions, by consistently feeding the cell with KOH solution. Owing to an excess feed solution, a momentary increase in the polarization resistance was observed immediately after the open-circuit. The excess feed solution was mostly recovered by subjecting the cell to the applied electric bias. Stability tests on the AEMWE cell under on-off cycling with continuous feeding even under an open circuit can guarantee long-term stability by avoiding an irreversible increase in ohmic and polarization resistances.

• Current Optics and Photonics
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• 제7권1호
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• pp.33-37
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• 2023

Real-time adaptive control of laser output polarization is presented in a 10-W-level non-polarization-maintaining (non-PM) fiber amplifier. While the output polarization from a non-PM fiber amplifier tends to be irregular, depending on output power, time, and perturbation, closed-loop polarization control can maintain the polarization extinction ratio at higher than 20 dB. Real-time polarization control can attain the target linear polarization mostly within 1.4-25 ms and shows stability against external perturbations. This approach can satisfy both linear polarization and high output power in a non-PM amplifier, and facilitates optimization of laser performance and maintenance-free operation.

• Corrosion Science and Technology
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• 제10권4호
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• pp.125-130
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• 2011

This study was performed to improve the corrosion resistance and the stability of passive film on copper tube by potentiostatic polarization method in synthetic tap water. Formation of passive film was carried out by anodic potentiostatic polarization at various passivation potentials and passivation times in 0.1 M NaOH solution. Stability of passive film and corrosion resistance was evaluated by self-activation time, ${\tau}_0$ from passive state to active state on open-circuit state in 0.1 M NaOH solution. Addition of polyphosphate in NaOH solution prolonged the self-activation time and improved the corrosion resistance, and the addition of 5 ppm polyphosphate was most effective. It was also observed that better corrosion resistance was obtained by potentiostatic polarization at 1.0 V (vs. SCE) than at any other passivation potentials. Passivated copper tube showed perfect corrosion resistance for the immersion test in synthetic tap water showing that the anodic potentiostatic polarization treatment in 0.1 M NaOH with 5 ppm polyphosphate solution would be effective in improving the corrosion resistance and preventing the blue water problem.

• Transactions on Electrical and Electronic Materials
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• 제15권2호
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• pp.60-65
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• 2014

This article explains the experimental results of ferroelectric polarization switching (FPS) of potassium nitrate ($KNO_3$) with different polymers such as polyvinylidene fluoride (PVDF) and polyvinyl fluoride (PVF) using simple melt-press techniques. To analyze the ferroelectric polarization switching in potassium nitrate ($KNO_3$) composite films at room temperature, we applied the Ishibashi and Takagi theory (based on Avrami model) to the switching current transient. To investigate the dimensionality of domain growth, the ferroelectric polarization switching current (FPS current) was observed from the square - wave bipolar signals across a resistance of $0.1k{\Omega}$ in series with the composite films. The existence of a switching current transient pulse confirmed the ferroelectricity and indicated the stability of the ferroelectric phase (phase III) of $KNO_3$ at room temperature. Polarization hysteresis (P-E) characteristics supported the prominent features of ferroelectric polarization switching in the composite films at room temperature.

• 폴리머
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• 제26권4호
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• pp.431-438
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• 2002

편광 푸리에 변환 적외선 분광법을 이용하여 액정 디스플레이의 배향막으로 널리 사용되는 폴리이미드 필름의 편광 자외선 조사에 따른 액정의 배향성과 열적 안정성을 연구하였다. 편광자외선이 조사된 폴리이미드의 경우, 조사된 편광자외선의 극성 방향에 평행한 폴리이미드 분자들의 우선적인 광분해 반응으로 인하여 편광자외선 조사 후 남아 있는 폴리이미드 분자들은 조사된 편광자외선 극성 방향과 수직 배향을 나타내었다. 하지만 러빙 처리된 폴리이미드 필름은 러빙 방향과 평행하게 폴리이미드 분자들의 재배향이 유도됨을 확인하였다. 또한 편광자외선이 조사된 폴리이미드 배향막이 편광자외선 조사를 통한 폴리이미드 분자들의 단편화 반응 때문에 러빙 처리된 폴리이미드 배향막 보다는 열적 안정성이 저하됨을 확인하였다.

• 반도체디스플레이기술학회지
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• 제17권3호
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• pp.70-74
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• 2018

In typical spectroscopic ellipsometry, the optical and geometrical properties of thin film and nano pattern can be obtained by measuring the polarization state of light reflected/transmitted from the object by rotating a analyzer or a compensator. We proposed a snapshot spectroscopic ellipsometric system based on a modified Michelson interferometer to overcome the time-consuring measurement principle due to rotating part. The proposed system provides spectral ellipsometric parameters (psi, delta) in real time by using a single spectral interference signal generated in the interferometric polarization module. However, it has a long-term stability problem resulting in delta(k) drift. In this paper, it is experimentally proved that the drift problem is caused by anisotropic refractive index change of the beam intersection layer in beam splitter of interferometer.

• 한국광학회지
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• 제4권4호
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• pp.487-492
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• 1993

편광유지 광섬유를 이용하여 자이로스코프를 구성하였다. 전체 시스템의 총 광 손실은 약 25dB였으며, 지구자전속도를 기준으로 하여 장기 drift와 단기 잡음을 측정하였다. 장기 drift는 온도변화와 밀접한 관계가 있었으며 약 $3^{\circ}/hr$ 정도의 값을 얻었고, 단기 근 잡음은 약 $0.6^{\circ}/hr/{\sqrt{Hz}}$의 값을 나타내었다.

• 한국표면공학회지
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• 제21권4호
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• pp.176-182
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• 1988

Effects of Cr, Ni and W on the anodic polarization behavior were investigated for Fe-Cr-Ni-W alloys in deaerated 1N HCI solution. Surface films formed on the polarization were analysed using AES, SEM and EDAX. A higerconcentration of tungten was found in the surface oxide film compared to the matrix. It played an importanet role on incresing the stability of the passive film. The presence of an adequate amount of Cr was essential to increase the pitting resistance of the alloys in acid chloride media. Under 12 wt%cr,alloys containing 6wt%W did not exhidit any passivity at all. The main role of Ni was to control the microstructure rather than to modify the corrosion resistance. In 23 cr-14Ni-^W alloy, the duplex microstructure of ferrite($\delta$-phase) in an austenic matrix was developed. The reson why proferred pitting appeared in austenite and ferrite/austenite interface was that ferrite had more amount of Cr and W than austenite.

• 반도체디스플레이기술학회지
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• 제20권3호
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• pp.178-183
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• 2021

This paper describes a dynamic spectroscopic ellipsometry based on dual-wavelength calibration. DSE provides ellipsometric parameters at rates above 20 Hz, but the interferometer's sensitivity to temperature makes it difficult for that proposed system to maintain stable 𝜟k over long periods of time. To solve this problem, we set up an additional path in the DSE to perform simulations of the polarization phase calibration method using dual wavelengths. Through simulation, we were able to eliminate most of the polarization phase error and maintain a stable 𝜟k in the long-term stability experiment for 10 hours. This is the result that the 𝜟k stability of the proposed system is improved tens of times compared to the existing system.

• 한국식품영양과학회지
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• 제27권3호
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• pp.508-517
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• 1998

We investigated the effects of godulbaegi extracts on the physiochemical properties of biological membranes as membrane stability and fluidity employing the phospholipid liposomal membrances as a biomembrane-mimetic system. The addition of the godulbaegi extracts to the phospholipid exterted great effects stagbilized the barrier function of the liposomal membranes in proportion to the concentration of the additive and significantly increased the membranes fluidity. The values of the fluorescence polarization of 1,6-diphenyl 1,3,5-hexatriene (DPH) decreased gradually as the temperature increased, and decreased abruptly near the phase transition temperature (Tm) of the liposome from gel to liquid crystalline state as usual. These results suggest that the activities of the godulbaegi extracts to enhance the stability and fluidity of the liposomal membranes have implication in their biological activities.