• Journal of IKEEE
• /
• v.25 no.1
• /
• pp.64-68
• /
• 2021

We demonstrate an effect of annealing temperature on imprinting process of BiLaO thin film for liquid crystal alignment. BiLaO prepared sol-gel process was deposited by spin coating on a glass substrate, and then transferred to a pre-fabricated aligned pattern which is fabricated on a silicon wafer by laser interference lithography. Thin film was annealed at different temperature of 100, 150, 200, and 250 ℃. From the polarized optical microscopy analysis, the liquid crystal orientation was not uniform at the annealing temperature of 200 ℃ or lower and the uniform liquid crystal alignment characteristics were confirmed at the annealing temperature of 250 ℃. From atomic force microscopy, the pattern was not transferred at a temperature of 200 ℃ or lower. In contrast, the pattern was transferred at 250 ℃. Anisotropy of the thin film was obtained by the alignment pattern transferred at a temperature of 250 ℃, and the liquid crystal molecules could be evenly oriented on the thin film. Therefore, it was confirmed that the liquid crystal alignment process by the imprinting process of the BiLaO oxide film was affected by the annealing temperature.

• Korean Journal of Optics and Photonics
• /
• v.16 no.6
• /
• pp.553-559
• /
• 2005

Pulsed terahertz (THz) radiation was generated by optical rectification and detected by a fee space electro-optic sampling (FS-EOS) method. We used ZnTe (110) crystals for both generation and detection. By coating dielectric anti-reflection film on the ZnTe crystal surface, we can reduce the reflectance of a pump laser beam from $30\%$ to $2\%$, and the terahertz pulse amplitude increased $27\%$ compared with an uncoated crystal. A wider bandwidth of THz radiation was obtained by using a thinner crystal but the signal intensity was decreased in this case. And variations of THz radiation by changing orientation of the ZnTe crystal with respect to the pump (or probe) laser polarization, and by changing the power of the pump laser have also been investigated and discussed.

• Applied Chemistry for Engineering
• /
• v.34 no.4
• /
• pp.347-356
• /
• 2023

Liquid crystal elastomer (LCE) fibers have been widely applied in various fields, such as soft robots and biomimetic actuators, in a one-dimensional form. LCEs possess the characteristics of both fluidity and solid order, as well as the elasticity of rubber, and exhibit stimulus-response based on these properties. In particular, by programming the responsiveness to various stimuli such as heat, light, electric fields, and magnetic fields in terms of shape-changing, various movements such as lifting, twisting, and rotating can be realized with high degrees of freedom. Therefore, LCE fibers have the potential for application in various fields such as artificial muscles, soft robots, wearable technologies, and sensing technologies. The research on liquid crystal elastomer fibers is evaluated to have high applicability in various fields in the Fourth Industrial Revolution as a smart material that can include various functionalities beyond simple fibers. In this review, we introduce the structure and basic characteristics of liquid crystal elastomer fibers, the latest research trends on orientation-based fabrication methods, and various applications such as artificial muscles, smart fabrics, and soft robots.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1163-1166
• /
• 2004

Cinnamate group is well-known for the dimerization reaction by ultra-violet irradiation and cinnamate polymers are studied for photo-alignment materials. The cinnamate groups of flexible polymer are found to produce LC alignment parallel to polarization direction of ultra-violet light, which is contrary to the LC orientation on conventional cinnamate polymers. The un-reacted cinnamate groups in the flexible polymer are also found to participate in cycloadducts formation by additional thermal reaction that preserves the orientation of cycloadducts, leading to the enhancement of thermal stability of LC alignment.

• Applied Science and Convergence Technology
• /
• v.24 no.1
• /
• pp.1-8
• /
• 2015

Protein immobilization on a gold surface plays an important role in the usefulness of biosensors that utilize gold-coated surfaces such as surface plasmon resonance (SPR), quartz crystal microbalance (QCM), etc. For developing high performance biosensors, it is necessarily required that immobilized proteins must remain biologically active. Loss of protein activity and maintenance of its stability on transducer surfaces is directly associated with the choice of immobilization methods, affecting protein-protein interactions. During the past decade, a variety of strategies have been extensively developed for the effective immobilization of proteins in terms of the orientation, density, and stability of immobilized proteins on analytical devices operating on different principles. In this review, recent advances and novel strategies in protein immobilization technologies developed for biosensors are briefly discussed, thereby providing an useful information for the selection of appropriate immobilization approach.

• The Korean Journal of Ceramics
• /
• v.3 no.4
• /
• pp.257-262
• /
• 1997

Aluminum nitride(AIN) thin films were deposited on SiO$_2$/Si substrates by reactive sputtering for the application of SAW devices. The major deposition parameters such as pressure, nitrogen fraction, rf power, substrate distance were changed to find out the optimal condition for c-axis oriented thin films on an amorphous substrate. The effects of deposition parameters on the crystal structure, residual stress, and growth morphology of thin films were characterized by XRD, SEM, and TEM. The FWHM of (002) rocking curve of the films deposited at the proper condition was lower than 2.2$^{\circ}$(C=0.93$^{\circ}$). Cross-sectional TEM showed that self-aligned structure was developed just after slightly random growth at the initial stage. The frequency characteristics of test device fabricated from AIN thin films confirmed their piezoelectric property and applicability for SAW devices.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.890-893
• /
• 2006

Effects of the evaporation rate of MgO films using electron beam were investigated on the MgO properties and the discharge characteristics of the plasma display panel (PDP). The evaporation rate was changed from 3 ${\AA}/sec$ to 15 ${\AA}/sec$ at a substrate temperature of $300\;^{\circ}C$. MgO properties such as crystal orientation, surface roughness, contact angle, and film structure were inspected using XPS, AFM, drop shape analysis and SEM. We also studied the relation between MgO properties and PDP discharging characteristics. The minimum firing voltage and maximum efficacy were obtained at evaporation rate of 5 ${\AA}/sec$. In the MgO film deposited at 5 ${\AA}/sec$, (200) orientation was most intensive and surface roughness was minimum.

• Proceedings of the KIEE Conference
• /
• 1995.11a
• /
• pp.420-422
• /
• 1995

PVDF (polyvinylidene fluoride) has at least from known crystalline structure ( ; they are referred to as the $\alpha$, $\beta$, $\gamma$ and $\alpha_p$ phase or forms II, I, III and $IV_p$). In this study, the manufactured PVDF thin films through vapor deposition method had for II ( ; the substrate temperature at 30$^{\circ}C$). The dielectric behavior of poly(vinylidene fluoride) is affected by orientation and crystal modification. The very high value of the dielectric constant for high temperature conditioned film is believed to be due to the orientation effect. The loss peak caused by molecular motion of the molecules in crystalline regions.

• Korean Journal of Materials Research
• /
• v.9 no.5
• /
• pp.473-477
• /
• 1999

Xerographic properties of double-layer photoconductor doped with 4-butyl-4'-methoxyazobenzene (BMAB) as charge-carrier transport material were investigated. BMAB can undergo reversible trans-cis isomerization by light with appropriate wavelength. In the results of measured surface voltage properties for photoconductor doped with BMAB, TNF: BMAB(4-wt%) sample with trans form showed the lowest dark decay, the lowest residual voltage, and the highest sensitivity among cis form. The trans isomer of BMAB has ordering orientation because the molecule possesses a rodlike shape, while the cis isomer has random orientation due to its bent shape. Therefore the molecular arrangement of trans form enhanced charge-carrier transport mobility.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07a
• /
• pp.550-552
• /
• 2003

We prepared $Co_{77}Cr_{20}Ta_3$ Magnetic layer for perpendicular magnetic recording media with introduce Two-step methode and Amorphous Si Underlayer on slide glass substrate. The thickness of magnetic layer were 100nm, and Underlayer were varied from 5 to 100 nm. The multi layer Properties of crystal structure were examined with XRD. Prepared thin films showed improvement of dispersion angle of c-axis orientation ${\Delta}{\theta}_{50}$ caused by inserting Buffer-layer and amorphous Si underlayer.