• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1893-1895
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• 2005

To measure electrical properties of semiconducting materials in power cable, we have investigated dielectric properties of EVA showed by changing the content of carbon black. The specimen was primarily kneaded in material samples of pellet form for 5 minutes on rollers ringing between $70[^{\circ}C]$ and $100[^{\circ}C]$. Then that was produced as sheets after pressing for 20 minutes at $180[^{\circ}C]$ with a pressure of 200[kg/cm]. The contents of conductive carbon black were 20, 30 and 40(wt%), respectively The dielectric properties of specimens were measured by dielectric thermal analyzer (CONCEPT 40, NOVOCONTROL). Measuring frequencies were 10, 60, 100, 1000, 10000, 100000, 1000000(Hz) and measuring temperatures were -40, -20, 20, $90[^{\circ}C]$. From above experimental result, permittivity was increased, while $tan{\delta}$ was decreased according to an increment of the content of carbon black.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.149-152
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• 1997

High-power piezoelectric materials are being developed for applications such as actuators and ultrasonic motors. In this paper, ferroelectric property of iron-doped 0.57 (Sc$_{1}$2//Nb$_{1}$2/)O$_3$-0.43 PbTiO$_3$. which is the morphotropic phase boundary composition for the PSN-PT system, was investigated. The maximum dielectric constant ( $\varepsilon$$_{33}$/$\varepsilon$$_{0}$ = 2551) and the minimum dielectric loss(tan $\delta$ = 0.51 %) at room temperature were obtained at 01. wt% and 0.3 wt% of iron additions. With additions of the Fe$_2$O$_3$ the electromechanical coupling factor of radial mode k$_{p}$ and the piezoelectric coefficient d$_{33}$ were slightly decreased, on the other hand the mechanical quality factor was increased significantly. The highest mechanical quality factor (Qm= 297) was obtained at 0.3 wt% Fe$_2$O$_3$, which is 4.4 times larger than that of pure 0.57 PSN-0.43PT ceramics. The temperature dependence of the dielectric constant and dielectic loss was observed between 2$0^{\circ}C$ and 35$0^{\circ}C$ .X> .X> .

• 한국인쇄학회지
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• 제30권2호
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• pp.59-68
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• 2012

As one of the eletronic device industries has been developed by using a recent printing method, the consumption of Ag paste has been on the rise as well. The printing method has simple processes in comparison with other methods. Also it enables to be large-scaled and to lower price ranges. If UV curing system would be applied to the printing method, energy consumption and dangerousness from curing system can be minimized in a short period of time so that its method can be more eco-friendly. This study conducted an experiment in order to make UV curing Ag paste which is feasible to implement micro patterns with different dispersing agents. The purpose of the study is to analysis the suitable printability for micro pattern and to test dispersibility, hardening properties, conductivity and adhesive stength by measuring viscosity, TI(thixotropy index), G', G", $tan{\delta}$(G"/G') after making paste. We have experimented with four dispersing agents. After We did an analysis of characteristic of rheology, conductivity and adhesive stength, etc, We confirmed that the paste added FP 3060 has excellent dispersibility, conductivity and adhesive stength. If the paste has excellent dispersibility, we will expect that micro pattern is made by that.

• 한국염색가공학회지
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• 제15권3호
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• pp.132-139
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• 2003

PTT[Poly(trimethylene terephthalate)] fibers was annealed by passing on the plate heater to illuminate the effects of annealing on the alkaline hydrolysis behavior properties with varying the treatment temperature for 0.5 second. The L010 and crystallinity were increased with increases in temperature. With the increases of the temperature, the dynamic viscoelastic behaviors were analyzed to be reduction in $T_{max}(tan\;\delta)$. The weight loss in alkaline solution was two times more rapid for the PTT annealed at $200^\circ{C}$ than the control samples. The kinetics of hydrolysis was confirmed that the hydrolysis of the PTT fibers in the alkaline solution was started from the surface of the fibers and selective to the amorphous region in continuation, on the basis of the results of the increase in crystallinity and the decrease in dye uptake at the initial stage of the hydrolysis.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.490-491
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• 2007

We have investigated dielectric polarization in organic light-emitting diodes using 8-hydroxyquinoline aluminum$(Alq_3)$ as an electron transport and emissive material. We analyzed the dielectric polarization of organic light emitting diodes using impedance. Impedance characteristics was measured complex impedance Z and phase ${\theta}$ in the frequency range of 40Hz to $10^8Hz$. We obtained dielectric constant and loss tangent (tan ${\delta}$) of the device. From these analyses, we are able to interpret a dielectric dispersion and dielectric absorption contributed by an interfacial and orientational polarization.

• 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%.%.%.%.%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.200-203
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• 2006

Prior to destructive testing, diagnostic tests were performed in eight high voltage motors. Diagnostic tests included polarization index, ac current, dissipation factor($tan{\delta}$) and partial discharge magnitude. The rewind of motor stator insulation at rated voltage is assessed by the results of these tests. After completing the diagnostic tests, the stator windings of motors were subjected to gradually increasing ac voltage, until the insulation punctured. No. 1 motor failed near rated voltage of 12.96 kV. The breakdown voltage of No. 4 motor was 6.99 kV which is lower that expected for good quality coils in 6.6 kV class motors. The failure was located in a line-end coil at the exit from the core slot. These two motors began operation in 1994. While testing No. 7 motor, flashover occurred between the stator winding and the stator frame at 15 kV. The relationship between the diagnostic test and the drop in insulation breakdown voltage was analyzed.

• Food Science and Biotechnology
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• 제15권4호
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• pp.589-594
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• 2006

The effect of five commercial gums (carboxylmethylcellulose, CMC; guar gum, GG; hydroxypropylmethyl-cellulose, HPMC; locust bean gum, LBG; and xanthan gum) at a concentration of 0.25% on the rheological properties of rice flour (RF) dispersions was investigated in steady and dynamic shear. The steady shear rheological properties showed that RF gum mixture dispersions (5%, w/w) at $25^{\circ}C$ had high shear-thinning flow behavior (n=0.20-0.31) exhibiting a yield stress. Magnitudes of consistency index (K), apparent viscosity (${\eta}_{a,100}$), and Casson yield stress (${\sigma}_{oc}$) of RF-gum mixtures were much higher than those of RF dispersion with no added gum (control). Activation energy values (6.67-10.8 kJ/mole) of RF-gum mixtures within the temperature range of $25-70^{\circ}C$ were lower than that (11.9 kJ/mole) of the control. Dynamic rheological data of log (G', G") versus log frequency (${\omega}$) of RF-gum mixtures had positive slopes (0.15-0.37) with G' greater than G" over most of the frequency range (0.63-63 rad/sec), demonstrating a frequency dependency. Tan ${\delta}$ (G"/G') values of RF-gum mixtures, except for xanthan gum, were much higher than that of the control.

• Tribology and Lubricants
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• 제35권3호
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• pp.151-157
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• 2019

Insulated oil degradation produces charged by-products, such as acids and hydro-peroxides, which tend to reduce the insulating properties of the oil. In this study, UV-vis spectroscopy measurement technology is developed and experimentally compared with other measurement methods, such as the titration method and IR spectroscopy, to validate its ability to monitor the degradation of electrical insulating paper. The degradation characteristics of the insulating paper are appropriately represented through various types of measurement methods, such as the Tan (delta) method, $CO_2$ gas production measurement, the titration method, and IR spectroscopy. The results are demonstrated to be well comparable to a change in the fluorescence emission ratio (FER), which is defined as the shift in fluorescence intensity in the measured wavelength range, and also to the chromatic ratio, which is defined as a color shift to longer wavelength ranges. The results also show that, by using UV-vis spectroscopy, it is possible to detect the degradation of the insulating paper. This study suggests that UV-vis spectroscopy can be applied as an alternative to high-performance liquid chromatography, which is the internationally recognized measurement technology for cellulose paper degradation. The FER detector is also verified to be useful as an effective condition-monitoring device for power transformers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권1호
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• pp.15-29
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• 2024

A fetoscope is an optical endoscope, which is often applied in fetoscopic laser photocoagulation to treat twin-to-twin transfusion syndrome. In an operation, the clinician needs to observe the abnormal placental vessels through the endoscope, so as to guide the operation. However, low-quality imaging and narrow field of view of the fetoscope increase the difficulty of the operation. Introducing an accurate placental vessel segmentation of fetoscopic images can assist the fetoscopic laser photocoagulation and help identify the abnormal vessels. This study proposes a method to solve the above problems. A novel encoder-decoder network with a dual-path structure is proposed to segment the placental vessels in fetoscopic images. In particular, we introduce a channel attention mechanism and a continuous convolution structure to obtain multi-scale features with their weights. Moreover, a switching connection is inserted between the corresponding blocks of the two paths to strengthen their relationship. According to the results of a set of blood vessel segmentation experiments conducted on a public fetoscopic image dataset, our method has achieved higher scores than the current mainstream segmentation methods, raising the dice similarity coefficient, intersection over union, and pixel accuracy by 5.80%, 8.39% and 0.62%, respectively.