• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.373-373
• /
• 2014

Resistive-change random access memory (ReRAM) device is one of the promising candidates owing to its simple structure, high scalability potential and low power operation. Many resistive switching devices using transition metal oxides materials such as NiO, Al2O3, ZnO, HfO2, $TiO_2$, have attracting increased attention in recent years as the next-generation nonvolatile memory. Among various transition metal oxides materials, HfO2 has been adopted as the gate dielectric in advanced Si devices. For this reason, it is advantageous to develop an HfO2-based ReRAM devices to leverage its compatibility with Si. However, the annealing temperature of these high-k thin films for a suitable resistive memory switching is high, so there are several reports for low temperature process including microwave irradiation. In this paper, we demonstrate the bipolar resistive switching characteristics in the microwave irradiation annealing processed Ag/HfO2/Pt ReRAM device. Compared to the as-deposited Ag/HfO2/Pt device, highly improved uniformity of resistance values and operating voltage were obtained from the micro wave annealing processed HfO2 ReRAM device. In addition, a stable DC endurance (>100 cycles) and a high data retention (>104 sec) were achieved.

• Applied Biological Chemistry
• /
• v.26 no.2
• /
• pp.82-89
• /
• 1983

In order to develop a commercial storage method of onions by irradiation combined with natural low temperature, two local varieties of onions, precocious species and late ripening, were stored at natural low temperature storage room ($450{\times}650{\times}250cmH.$; year-round temperature change, $2{\sim}17^{\circ}C$; R.H., $80{\sim}85%$) on batch scale following irradiation with optimum dose level. Precocious and late varieties were all sprouted after five to seven months storage, whereas $10{\sim}15$ Krad irradiated precocious variety was $2{\sim}4%$ sprouted after nine months storage, but sprouting was completly inhibited at the same dose for late variety. The extent of loss due to rot attack after ten months storage were $23{\sim}49%$ in both control and irradiated group of precocious variety but those of late variety were only $4{\sim}10%$. The weight loss of irradiated precocious variety after ten months storage was $13{\sim}16$, while that of late variety was $5.3{\sim}5.9%$ after nine months storage. The moisture content, during whole storage period, of two varieties were $90{\sim}93$ with negligible changes. The total sugar content differed little with varieties and doses immediatly after irradiation, but decreased by the elapse of storage period. 33.6% of its content was decreased in control and 12.5% in irradiated group but $20{\sim}26$ decreased in both control and irradiated group of late variety after nine months storage. No appreciable change was observed immediately after irradiation irrespective of variety and dose, but decreased slightly with storage. Ascorbic acid content of precocious variety was increased slightly with dose immediately after irradiation, but those of late variety decreased slightly. Ascorbic acid content were generally decreased during whole storage period. An economical preservation method of onions appliable to late variety, would be to irradiate onion bulbs at dost range of $10{\sim}15$ Krad followed by storage at natural low temperature storage room.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.42 no.11
• /
• pp.1857-1863
• /
• 2013

Bulgogi sauces containing electron beam-irradiated garlic powder (1%, 3%, and 5%) were used to compare their irradiation status before and after pasteurization ($85^{\circ}C$, 30 min), using a thermoluminescence (TL) analysis by two different laboratories. The sauces with non-irradiated ingredient only provided a background TL glow curve with a maximum peak after $300^{\circ}C$. However, the presence of irradiated ingredient (1 and 10 kGy) was evident through the typical TL glow curves in a temperature range of 150 to $250^{\circ}C$. The concentration of irradiated ingredients showed a greater impact on identification characteristics than their radiation doses. TL ratios ($TL_1/TL_2$) were not able to confirm the results showing evidence of irradiation through the TL glow curve shapes. Pasteurization showed a negligible effect on the key identification parameters and did not change the shape or temperature range of radiation-specific TL glow peak, but reduced TL glow curve intensity. TL glow curve shape with the maximum peak in a temperature range of $150{\sim}250^{\circ}C$ was the most useful characteristic providing information required for confirming the irradiation status.

• Polymer(Korea)
• /
• v.35 no.5
• /
• pp.444-450
• /
• 2011

A high molecular weight natural sodium alginate (HMWSAs) was depolymerized by hydrogen peroxide ($H_2O_2$) with ultrasonic irradiation. The effects of the reaction conditions such as reaction temperature, reaction time, hydrogen peroxide concentration and ultrasonic irradiation time on the molecular weights and the end groups of the depolymerized alginates were investigated. It was revealed that depolymerization occurred through the breakage of 1,4-glycosidic bonds of sodium alginate and the formation of formate groups on the main chain under certain conditions. The changes in molecular weight were monitored by GPC-MALS. The molecular weight of 2 wt% alginate solution decreased from 450 to 15.9 kDa for 0.5 hrs at 50 $^{\circ}C$ under an appropriate ultrasonic irradiation. The PDI(polydispersity index)s of the alginate depolymerized in this study were considerably narrow in comparison with those obtained from the other chemical degradation method. The PDIs were in the range of 1.5~2.5 in any reaction conditions employed in this study.

• Korean Journal of Food Science and Technology
• /
• v.30 no.5
• /
• pp.1058-1063
• /
• 1998

As a series of study on the hygienization and long-term storage of dried red pepper and red pepper powder using gamma irradiation, water activity and fatty acid composition were monitored for stored samples. In proximate composition of dried pepper, moisture contents were 21.75 % in pericarp and 9.30% in seed, and crude fats were 7.20% (fresh wt.) in pericap and 22.50% in seed, respectively. Proximate components were stable against irradiation up to 10 kGy. Moisture contents and water activity of packaged samples in PE (0.1mm)/polycloth (whole pepper) and in nylon $15\;{\mu}m/PE\;100\;{\mu}m$ (pepper powder) were not remarkably changed during storage for 9 months under room temperature $(3{\sim}30^{\circ}C,\;RH\;50{\circ}95%,\;whole\;pepper,\;powder)$ and low temperature $(5{\sim}10^{\circ}C,\;pepper\;powder)$, respectively. Fatty acids of dried red pepper were mainly composed of linoleic acid, oleic acid, palmitic acid and linolenic acid. Particularly higher composition of unsaturated fatty acids were observed in seed $(84{\sim}85%)$ than in pericarp $(73{\sim}76%)$, and which showed negligible changes during post irradiation period for 6 months.

• Proceedings of the IEEK Conference
• /
• 2009.05a
• /
• pp.159-162
• /
• 2009

The necessity of radiation dosimeter with precise measurement of radiation dose is increased and required in the field of spacecraft, radiotheraphy hospital, atomic plant facility, etc. where radiation exists. Until now, a low power commercial metal-oxide semiconductor(MOS) transistor has been tested as a gamma radiation dosimeter. The measurement error between the actual value and the measurement one can occur since the MOSFET(MOS field-effect transistor) dosimeter, which is now being used, has two gates with same width. The measurement value of dosimeter depends on the variation of threshold voltage, which can be affected by the environment such as temperature. In this paper, a radiation dosimeter having a pair of MOSFET is designed in the same silicon substrate, in which each of the MOSFETs is operable in a bias mode and a test mode. It can measure the radiation dose by the difference between the threshold voltages regardless of the variation of temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07a
• /
• pp.457-460
• /
• 2004

Many of the physical and chemical properties of polymer materials can be altered by high energy radiation. In the present work the exposure to radiation of low density polyethylene(LDPE) included antioxidants was carried out at various doses up to 600kGy at a dose rate of 5kGy/hr in the presence of air at room temperature. The study of the irradiation effects on the material properties has been make by different methods in an integrated way. The experimental data indicate that the decomposition onset temperature(DOT), the crystallinity and the thermoluminescence(TL) with radiation dose. DOT, crystallinity and TL analysis from irradiated PE samples provides useful data for the characterization of radiation-induced oxidation effects on these samples.

• Journal of the Korean Society of Safety
• /
• v.14 no.2
• /
• pp.77-82
• /
• 1999

In this paper, physical properties and electrical conductivity of electron beam irradiated low density polyethylene are studied. The specimens of thickness 100 $\mu\textrm{m}$ irradiated as each 1 Mrad, 2 Mrad, 4 Mrad, 8 Mrad, 16 Mrad and virgin are used in this experiment. FTIR analysis shows strong absorptions by methyl groups in wavenumbers 720 $cm^{-1}$ and 1463 $cm^{-1}$, and did not show any evidences of the presence of residual carbonyl groups. From the DSC analysis, the crystalline melting point of electron beam irradiated specimen is lower than that of virgin specimen. 1 Mrad irradiated sample shows the stable electrical conductivity characteristics with both temperature and electric field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.11a
• /
• pp.82-85
• /
• 1996

It is considered that the effect of radiation aging, such as electron beam due to the ultra-high voltage for transmission, on the physical properties and electrical characteristics of electrital insulating materials. Low-density polyethylene(thickness 100[${\mu}{\textrm}{m}$]) is selected as an experimental specimen. Fourier transform infra-red spectrum, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy is used so as to analysis the physical properties, the morphological changes and the crystallinity of LDPE. And it is made an experiments of dielectric characteristics in the temperature range of 20[$^{\circ}C$]~120[$^{\circ}C$], in the frequency range of 30[Hz]~1.5$\times$10$^{5}$ [Hz] and in the applied voltage range of 300[mV]~1500[mV].

• Korean Journal of Ecology and Environment
• /
• v.46 no.4
• /
• pp.513-523
• /
• 2013

This ecological study was conducted to analyze seasonal variation characteristics of Zostera marina at HAENAM SAGUMI on the Southern Coast of Korea. Environmental characteristics, plant morphological characteristics, shoot density, biomass, and leaf production were monitored from August 2008 to March 2011. Zostera marina occurred in the subtidal zone from 0 to 2.5 m below the mean low water level. Water temperature showed a clear annual pattern, with increase in spring and summer, and decreases in fall and winter. Irradiance showed seasonal variation, even though daily weather condition has short-term variation in the incident irradiation. Plant morphological characteristics, shoot density, biomass, and leaf production showed clear seasonal variation. Seasonal variation in the above biomass of Zostera marina was mainly caused by changes in shoot length. We found that there are correlations between environmental characteristics (water temperature, irradiation) and the growth of Zostera marina. There is stronger correlation between water temperature and the growth of Zostera marina, compared to the correlation between irradiation and the growth of Zostera marina. In particular, the growth of Zostera marina is inhibited by both higher and lower water temperature.