• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.12
• /
• pp.872-877
• /
• 2013

In this study, the leakage current - voltage characteristic and leakage current - time characteristic for the undegradated Ethylene Propylene Rubber and the Ethylene Propylene Rubber which is degradated by water tree for 200 hours have been measured on the temperature range of $50{\sim}80^{\circ}C$ and applied DC voltage range of 200 V~800 V for 90 minutes. The results of this study are listed below. In case the temperature is $50^{\circ}C$, it founds that the leakage current have shown a increase in proportion to the applied voltage as 2 pA in 200 V, 6 pA in 400 V, 10 pA in 600 V and 15 pA in 800 V. It founds that the leakage current increased with the rise of temperature. It founds that the leakage current was consistent as time goes by, the leakage current of the sample degradated by water tree for 200 hours has increased more than undegradated sample.

• Analytical Science and Technology
• /
• v.16 no.4
• /
• pp.269-276
• /
• 2003

A new type of stripping voltammetry, inverted catalytic stripping voltammetry $IC_tSV$, is introduced. The rhodium-formaldehyde complex in hydrochloric acid gives an inverted catalytic hydrogen peak (reduction current peak during positive-going scan). The characteristics of the inverted peak were studied. By using the peak as analytical peak the detection limit of $1.2{\times}10^{-10}M$ Rh (50s preconcentration) can be reached at the optimal conditions: 0.015% (W/V) HCHO-0.42 M HCl; accumulation potential, -1.1 V; scan rate, 100 mV/s.

• Transactions on Electrical and Electronic Materials
• /
• v.16 no.6
• /
• pp.308-311
• /
• 2015

V₂O₅/Mn₃O₄/Nb₂O₅ codoped zinc oxide varistor ceramics were sintered at a temperature range as low as 875~950℃. The voltage clamping characteristics of V₂O₅/Mn₃O₄/Nb₂O₅ codoped zinc oxide varistor ceramics were investigated at a pulse current range of 1~50 A. The sintering temperature had a significant effect on clamp voltage ratio, which exhibits surge protection capabilities. The varistor ceramics sintered at 875℃ exhibited the best clamping characteristics, in which the clamp voltage ratio was 2.69 at a pulse current of 50 A. The varistor ceramics sintered at 900℃ exhibited the highest electrical stability, where = 3,824 V/cm (initial 3,909 V/cm), and E_{1 mA/cm²} = 27 (initial 39) after application of a pulse current of 100 A.

• Journal of the Korea Fashion and Costume Design Association
• /
• v.2 no.1
• /
• pp.113-121
• /
• 2000

The effect of Sunlight exposure on reducing the microorganism counts in the bedding materials was experimented by using 3 kinds of microorganisms(S. aureus, K. pnenmoniae and E. coli) and 3 kinds of fabrics (cotton, silk and polyester). Counts of the microorganism were examined before and after sunlight exposure. The sunlights were controlled U.V and Daylight D50 using MacBeth artificial light source. The specimens were exposed for 5 min, 10 min and 30 minutes under the $20^{\circ}C$ and 60% R.H, distance is 50cm from the light source. Results were as follows, 1. The reduction rate of the 3kinds of microorganisms was remarkably great under the U.V exposure. The U.V. exposure was very effective way to sterlize the bedding materials in the house care. 2. S. aureus was the most susceptible to U.V. exposure and the sunlight exposure. E. coli was the most resistant to the U.V and the sunlight exposure. 3. The reduction rate of the 3 kinds of fabrics was not significantly different. The polyester is more resistant than the silk and the cotton. Those were shown good reduction rate if all kinds of microorganism under the U.V and daylight.

• Proceedings of the IEEK Conference
• /
• 2001.10a
• /
• pp.759-764
• /
• 2001

The separation performance of zigzag air classifier with angle of 90 degrees was studied using narrow size fractions of thin square samples and granular samples. The simulation results of air velocity inside the classifier indicated that the zigzag geometry induces a new pattern consisting of an upward flow and a circulation flow, Experimental results showed that overflow product recovery was described as an integral calculus of normal distribution as a function of dimensionless air velocity ( $V_{A}$ $V_{A50}$), where $V_{A}$ is superficial air velocity and $V_{A50}$ is the $V_{A}$ at the fifty percent recovery. The $V_{A}$ values were predicted using the equations derived from dynamics for a particle dropping in air. A monitoring system that utilizes changes in acoustic signals emitted during the process of air classification was developed to separate PET with desired recovery or grade. The technical feasibility of the on-line monitoring of the PET recovery and grade was demonstrated by measuring relative energy of the signals.signals.als.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1252-1253
• /
• 2008

The $V_{1.8}W_{0.2}O_5$ thin films deposited on $Pt/Ti/SiO_2/Si$ substrates by RF sputtering method with different $Ar/O_2$ ratio. The $V_{1.8}W_{0.2}O_5$ thin films were measured electrical and structural properties, fairly good Temperature coefficient of resistance(TCR). It was found that electrical and structural properties, TCR properties of thin films were strongly dependent upon the $Ar/O_2$ ratio. The dielectric constant of the $V_{1.8}W_{0.2}O_5$ thin films with 50/20 ratio were 93 with a dielectric loss of 0.535, respectively. Also, the TCR values of the $V_{1.8}W_{0.2}O_5$ thin films with 50/20 ratio were -3.15%/$^{\circ}C$.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2000.01a
• /
• pp.175-176
• /
• 2000

Electric fields and the wall voltages in a surface-type AC PDP cell were measured using a Laser Induced Fluorescence Spectroscopy. For the condition of He 100Torr, 200V sustain voltage and 50kHz sustain frequency, the wall voltage dropped from about 50V to about -75V within $1{\mu}sec$ after the main discharge. And the wall voltage decreased with the rate of $10.8V/{\mu}sec$ due to the accumulation of the space charges after $1{\mu}sec$. But when the operating pressure was 40Torr, it increased with the rate of $4.5V/{\mu}sec$ because the diffusion effect of the wall charge on MgO surface was more dominant than the accumulation effect of the space charges. During the pulse-off period, the wall voltage decreased slightly due to the diffusion of the wall charge. When the sustain voltage was 250V, the self-erasing discharge occurred, and the absolute value of the wall voltage decreased rapidly just after the pulses were off, which was caused by the accumulation of the charges generated by the self-erasing discharge.

• Korean Chemical Engineering Research
• /
• v.46 no.1
• /
• pp.69-75
• /
• 2008

Discharge capacity of $LiCoO_2$ in preparation by mechanochemical process decreased remarkably over 4.3V. However, Zr coating of $LiCoO_2$ showed very stable electrochemical properties up to 4.5V. Zr coating of $LiCoO_2$ in this experiment showed the discharge capacity of 197 mAh/g at 3.0-4.5V, and it maintained 96% of the initial discharge capacity after 50 cycle of charge/discharge.

• Journal of the Korean Vacuum Society
• /
• v.18 no.5
• /
• pp.352-357
• /
• 2009

The InAs multi-quantum dots (MQDs) solar cell and InGaAs multi-quantum wells (MQWs) solar cell to cover 1.1 eV and 1.3 eV were designed by 1D poisson, respectively. The MQDs and MQWs of 5, 10, 15 layers were grown by molecular beam epitaxy. The photo luminescence results showed that the 5 period stacked MQDs have the highest intensity at around 1.1 eV with 57.6 meV full width at half maximum (FWHM). Also we can observe 10 period stacked MQWs peak position which has highest intensity at 1.31 eV with 12.37 meV FWHM. The density and size of QDs were observed by reflection high energy electron diffraction pattern and atomic force microscope. Futhermore, AlGaAs/GaAs sandwiched tunnel junctions were modified according to the width of GaAs layer on p-type GaAs substrates. The structures with GaAs width of 30 nm and 50 nm have backward diode characteristics. In contrast, tunnel diode characteristics were observed in the 20 nm of that of sample.

• Food Science and Preservation
• /
• v.16 no.5
• /
• pp.765-771
• /
• 2009

Anti-oxidative activities of Heracleum moellendorffii Hance extracts were measured after extraction with 50% (v/v) ethanol or water (at $80^{\circ}C$ or $20^{\circ}C$). The total polyphenol content was highest (64.73 mg GAE/g) in extract from 50% ethanol extraction at $80^{\circ}C$. In extracts obtained by water extraction at $80^{\circ}C$ and $20^{\circ}C$, the total polyphenol contents were 39.78 mg GAE/g and 23.17 mg GAE/g, respectively. The antioxidant activities of the ethanol extract at $80^{\circ}C$ were highest, as assessed by DPPH radical scavenging activity (69.14% at 50 ppm), reducing power (OD 0.93), and $ABTS^+$ radical-scavenging activity (85.62% at 1,000 ppm). At $80^{\circ}C$, the antioxidant activity of the 50% (v/v) ethanol extract was 8-20% higher than that of the water extract. Also, the chemical composition of extract from ethanol extraction at $80^{\circ}C$ was analyzed. The levels of moisture, crude protein, crude fat, and crude ash were 6.38%, 4.35%, 0.67%, and 1.96%, (all w/w), respectively. The Na, K, Mg, Zn, Fe, Ca, and P contents of the extract were 53.41, 398.26, 5.80, 0.40, 5.27, 3.56, and 47.17 mg/100 g, respectively. The total levels of polyphenolic compounds and flavonoids in the ethanol extract were 64.73 mg GAE/g and 49.54 mg RE/g.