• Title/Summary/Keyword: low temperature irradiation

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Optimal Electropolishing Condition of Austenitic Stainless Steel Specimens for Slow Strain Rate Tensile Testing (오스테나이트 스테인리스강 저속인장시험편의 최적 전해연마 특성)

  • Min-Jae Choi;Eun-Byeoul Jo;Dong-Jin Kim
    • Corrosion Science and Technology
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    • v.22 no.6
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    • pp.457-465
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    • 2023
  • Irradiation-assisted stress corrosion cracking (IASCC) is one of the main degradation mechanisms of austenitic stainless steels, which are used as reactor internal materials. Slow strain rate testing (SSRT) has been widely applied to evaluate the IASCC initiation characteristics of proton-irradiated tensile specimens. Tensile specimens require low surface roughness for micro-crack observation, and electropolishing is the most important specimen pre-treatment process used for this. In this study, optimal electropolishing conditions were examined through analyzing results of polarization experiments and surface roughness measurements after electropolishing. Corrosion cell and electropolishing equipment were fabricated for polarization tests and electropolishing experiments using SSRT specimens. The experimental parameters were electropolishing time, current density, electrolyte temperature, and stirring speed. The optimal electropolishing conditions for SSRT tensile specimens made of type 316 stainless steel were evaluated as a polishing time of 180 seconds, a current density of 0.15 A/cm2, an electrolyte temperature of 60 ℃, and a stirring speed of 200 RPM.

A Development and Validation of Cosmetic Container Based on L-Ascorbic Acid Oxidation Property (L-Ascorbic Acid의 산화특성에 따른 화장품 용기 개발 및 유효성 분석)

  • Yoon, Sungwook
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.39 no.2
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    • pp.149-158
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    • 2013
  • L-ascorbic acid, the representative antioxidants, has a great effect on skin whitening, collagen synthesis, and anti-aging, but has low oxidative stability during storage. Therefore, in this study, thermal and oxidation properties of L-ascorbic acid under various storage conditions (powder, aqueous phase, changes of temperature, UV-irradiation, and inflow of external air etc.) were investigated. And the storage stability of ingredient was validated in the double-spaced pouch by analysing oxidation properties under each storage conditions (powder phase and blended with essence). In oder to analyze the thermal properties, TGA, DSC, and FT-IR analysis were carried out and UV-visible spectrophotometer & redox titration were used in parallel for oxidation property analyses. From the result of experiment, L-ascorbic acid was oxidized fast when it contained lots of metallic ion, hydroxy ion in aqueous solution under high temperature, UV-irradiation & inflow external air, whereas it was not oxidized for a long time when it was stored as pure powder although it has same condition as heating up, UV-irradiation & inflow external air. Based on this result, retention period of cosmetics which is using L-ascorbic acid, less stable material in oxidation can be innovatively increased when using double-spaced pouch that is designed and produced for separating storage of active ingredients.

Synthesis of P2O5-V2O5-ZnO Glass Frit for Laser Sealing of OLED by the Addition of Filler (필러 첨가에 의한 OLED의 레이저 실링용 P2O5-V2O5-ZnO 유리프릿의 제조)

  • Bang, Jae-Chul
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.9
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    • pp.571-576
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    • 2015
  • In this study, we developed a lead-free $P_2O_5-V_2O_5-ZnO$ glass frit for sealing OLED using laser irradiation. The frit satisfied the characteristics required for laser sealing such as low glass transition temperature, low coefficient of thermal expansion (CTE), high water-resistance, and high absorption at the wavelength of the laser beam. Ceramic fillers were added to the glass frit in order to further reduce and match its CTE with that of the commercial glass substrate. The addition of Zirconium Tungsten Phosphate (ZWP) to the frit yielded the most desirable results, reducing the CTE to $45.4{\times}10^{-7}/^{\circ}C$, which is very close to that of the glass substrate ($44.0{\times}10^{-7}/^{\circ}C$). Successful formation of a solid sealing layer was observed by optical and scanning electron microscopy.

Effect of the Storage Temperature, Duration and Gamma Irradiation on the Respiration Rate and Sugar Content of Minituber 'Superior'

  • Lim, Ji-Hyeok;HwangBo, Jun-Kwon;Baek, Myung-Hwa;Kim, Jin-Hong;Kim, Jae-Sung;Lee, Myung-Chul
    • Korean Journal of Environmental Agriculture
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    • v.24 no.1
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    • pp.61-65
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    • 2005
  • This study was to evaluate whether ionizing gamma radiation could be applied to break the dormancy of a potato minituber. The respiration rate of the minitubers was significantly affected by the storage temperature and a low dose gamma radiation. Ionizing radiation of 8 Gy enhanced the respiration rate of the potato tuber stored at $10^{\circ}C$ for 20 days. The potato tuber subjected to 4 and 8 Gy after 40 days storage at 10 and $20^{\circ}C$ exhibited higher respiration rates compared to the control (non-irradiated), but not at st. However, the ionizing radiation did not exhibit on significant effect on the respiration rate of the potato tuber stored for 60 days. It was observed that minitubers stored for 20 days had significant response to the storage temperature in terms of the total sugar content the higher the storage temperature, the lower the total sugar content. It was measured that the reducing sugar content was increased under the storage conditions both 5 and $10^{\circ}C$ for 40 days, but not to $20^{\circ}C$. The total sugar contents in the minituber stored for 60 days were similar to those stored for 40 days. The data was discussed on the relationships among the storage duration, temperature and ionizing radiation.

Effect of Calcination Temperature on the Microstructure and Photocatalytic Activity of Electrospun BiVO4 Nanofiber (전기방사를 이용하여 합성한 BiVO4 나노섬유의 미세구조와 광촉매 특성에 하소 온도가 미치는 영향)

  • Ji, Myeongjun;Kim, Jeong Hyun;Ryu, Cheol-Hui;Ko, Yun Taek;Lee, Young-In
    • Journal of Powder Materials
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    • v.27 no.3
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    • pp.226-232
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    • 2020
  • Bismuth vanadate (BiVO4) is considered a potentially attractive candidate for the visible-light-driven photodegradation of organic pollutants. In an effort to enhance their photocatalytic activities, BiVO4 nanofibers with controlled microstructures, grain sizes, and crystallinities are successfully prepared by electrospinning followed by a precisely controlled heat treatment. The structural features, morphologies, and photo-absorption performances of the asprepared samples are systematically investigated and can be readily controlled by varying the calcination temperature. From the physicochemical analysis results of the synthesized nanofiber, it is found that the nanofiber calcines at a lower temperature, shows a smaller crystallite size, and lower crystallinity. The photocatalytic degradation of rhodamine-B (RhB) reveals that the photocatalytic activity of the BiVO4 nanofibers can be improved by a thermal treatment at a relatively low temperature because of the optimization of the conflicting characteristics, crystallinity, crystallite size, and microstructure. The photocatalytic activity of the nanofiber calcined at 350℃ for the degradation of RhB under visible-light irradiation exhibits a greater photocatalytic activity than the nanofibers synthesized at 400℃ and 450℃.

A Study on the Performance of 100 W Thermoelectric Power Generation Module for Solar Hot Water System (태양열 온수 시스템에 적용 가능한 100 W급 열전발전 모듈 성능에 관한 연구)

  • Seo, Ho-Young;Lee, Kyung-Won;Yoon, Jeong-Hun;Lee, Soon-Hwan
    • Journal of the Korean Solar Energy Society
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    • v.39 no.1
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    • pp.21-32
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    • 2019
  • Solar hot water system produces hot water using solar energy. If it is not used effectively, overheating occurs during the summer. Therefore, a lot of research is being done to solve this. This study develops thermoelectric power module applicable to solar hot water system. A thermoelectric material can directly convert thermal energy into electrical energy without additional power generation devices. If there is a temperature difference between high and low temperature, it generate power by Seebeck effect. The thermoelectric module generates electricity using temperature differences through the heat exchange of hot and cold water. The water used for cooling is heated and stored as hot water as it passes through the module. It can prevent overheating of Solar hot water system while producing power. The thermoelectric module consists of one absorption and two radiation part. There path is designed in the form of a water jacket. As a result, a temperature of the absorption part was $134.2^{\circ}C$ and the radiation part was $48.6^{\circ}C$. The temperature difference between the absorption and radiation was $85.6^{\circ}C$. Also, The Thermoelectric module produced about 122 W of irradiation at $708W/m^2$. At this time, power generation efficiency was 2.62% and hot water conversion efficiency was 62.46%.

Characteristics of Thermoluminescence and Electron Spin Resonance and Organoleptic Quality of Irradiated Raisin and Dried Banana During Storage (건포도와 건바나나의 감마선 조사와 저장기간에 따른 열발광 및 전자스핀공명 특성과 관능적 품질)

  • Jo, Deok-Jo;Kwon, Joong-Ho
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.31 no.4
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    • pp.609-614
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    • 2002
  • The characteristics of thermoluminescence (TL) and electron spin resonance (ESR) and organoleptic qualities of gamma-irradiated raisin and dried banana were investigated during storage at 4$^{\circ}C$ for 6 months. The minerals separated from non-irradiated raisins showed TL glow curve (TL$_1$) with very low intensity around 200~30$0^{\circ}C$, while the irradiated samples at 1 kGy or more showed glow curves with higher intensity around 18$0^{\circ}C$, with linear increase by irradiation dose ($R^2$=0.9684), which made it possible to identify irradiated samples during 6 months. Moreover, TL ratios (TL$_1$/TL$_2$) through the reirradiation step at 1 kGy enhanced confidence in the identification of irradiated raisins. The ESR signals of multicomponent lines resulted from crystalline sugar radicals were shown in irradiated banana, identifying irradiated samples. The ESR signal intensity was dependent on irradiation doses ($R^2$=0.8977) and the signals were stable enough to be detected by 6th month after storage. Considering tile marketability of irradiated dried fruits during 6 months at low temperature TL and ESR analyses were shown suitable for the identification of irradiated raisins and dried banana, respectively.

Germination Properties of Rice and Glutinous Rice Exposed to Gamma Irradiation (감마선 조사된 벼와 찰벼의 검지를 위한 발아특성 비교)

  • 오경남;김경은;양재승
    • Journal of Food Hygiene and Safety
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    • v.16 no.1
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    • pp.76-81
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    • 2001
  • The germination test was used to detect biological changes in irradiated rice and glutenous rice at low doses. Grains were irradiated at below 0.5 kGy, husked and placed on distilled water moistend filter paper in a covered petri-dish. A germination test of 20 grains was carried out at room temperature for 5 days. The shoots and roots of non-irradiated rices grew well in comparison with those of irradiated rices above 0.3 kGy. The roots of rices were more sensitive to irradiation than the shoots, and the growth of roots was significantly decreased with the increasing doses. In glutinous rices, the growth of shoots and roots was retarded by irradiation at 0.2 kGy or more after 3rd days. We concluded that if the shoot or root length is 10 mm or longer within 5 day, the rices and glutinous rices are identified as non-irradiated.

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Effect of Gamma Irradiation on the Microbiological and Physicochemical Qualities of Vacuum-Packaged Sugar-Treated Waxy Corns During Storage (저장 중 진공포장 설탕침지 찰옥수수의 미생물 및 이화학적 특성에 대한 감마선조사의 영향)

  • Choi, Jae-Ho;Oh, Deog-Hwan
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.35 no.6
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    • pp.768-773
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    • 2006
  • Effect of gamma irradiation on the microbiological and physicochemical characteristics of vacuum-packaged sugar-treated corns was examined to improve taste and shelf-life during storage at room or low temperature. When the vacuum-packaged sugar-treated corns were stored at $25^{\circ}C$ for 7 months, total counts and yeast and molds in the control increased approximately 2.4 and 3.5 log CFU/g, respectively but complete inactivation was observed for irradiated corns at 3 and 5 kGy. Similar results were observed at $15^{\circ}C\;and\;4^{\circ}C$ storage. There were no significant differences in hardness between irradiated sugar-treated waxy corns and control group before storage, but the hardness in control significantly increased during the storage, compared to those of irradiated corns. Also, changes in sugar content were not significant between the irradiated sugar-treated waxy corns and control during storage. Sensory evaluation for steamed-waxy corns showed that total sensory scores were higher in irradiated corns than in control, which were increased with irradiation doses. It was considered that maintaining good quality and increasing shelf-life of irradiated vacuum-packaged sugar treated corns could be possible at $15^{\circ}C$ storage for long-term period.

Hybrid Fabrication of Screen-printed Pb(Zr,Ti)O3 Thick Films Using a Sol-infiltration and Photosensitive Direct-patterning Technique (졸-침투와 감광성 직접-패턴 기술을 이용하여 스크린인쇄된 Pb(Zr,Ti)O3 후막의 하이브리드 제작)

  • Lee, J.-H.;Kim, T.S.;Park, H.-H.
    • Journal of the Microelectronics and Packaging Society
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    • v.22 no.4
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    • pp.83-89
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    • 2015
  • In this paper, we propose a fabrication technique for enhanced electrical properties of piezoelectric thick films with excellent patterning property using sol-infiltration and a direct-patterning process. To achieve the needs of high-density and direct-patterning at a low sintering temperature (< $850^{\circ}C$), a photosensitive lead zirconate titanate (PZT) solution was infiltrated into a screen-printed thick film. The direct-patterned PZT films were clearly formed on a locally screen-printed thick film, using a photomask and UV light. Because UV light is scattered in the screen-printed thick film of a porous powder-based structure, there are needs to optimize the photosensitive PZT sol infiltration process for obtaining the enhanced properties of PZT thick film. By optimizing the concentration of the photosensitive PZT sol, UV irradiation time, and solvent developing time, the hybrid films prepared with 0.35 M of PZT sol, 4 min of UV irradiation and 15 sec solvent developing time, showed a very dense with a large grain size at a low sintering temperature of $800^{\circ}C$. It also illustrated enhanced electrical properties (remnant polarization, $P_r$, and coercive field, $E_c$). The $P_r$ value was over four times higher than those of the screen-printed films. These films integrated on silicon wafer substrate could give a potential of applications in micro-sensors and -actuators.