• Title/Summary/Keyword: HTO

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Investigation into Tritium Behaviour in Chinese cabbage and Rice after a Short-term Exposure of HTO (HTO 피폭후 배추와 벼에서 삼중수소 거동)

  • Kim, Sang-Bog;Lee, Myung-Ho;Choi, Gun-Sik;Choi, Young-Mo;Lee, Chang-Woo
    • Journal of Radiation Protection and Research
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    • v.23 no.2
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    • pp.75-82
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    • 1998
  • Tritium concentration in the atmosphere during HTO exposure was different between two experiments due to different velocity of HTO evaporation. Assimilation rate of the rice plant was considered to be higher than that of Chinese cabbage The uptake of atmospheric HTO into tissue free water tritium(TFWT) was higher in rice plants than in Chinese cabbage. However, organically bound tritium(OBT) concentration is relatively higher in Chinese cabbage than in rice. The specific activity ratio(SAR) increased slowly after HTO exposure and decreased gradually with time. The behaviour of HTO in the soil was affected by the environmental conditions.

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Evaluation of Hybrid Thermal Oxidation(HTO) System for Removal of MEK(Methyl ethyl ketone) and Toluene (복합열산화(Hybrid Thermal Oxidation) 시스템을 이용한 MEK(Methyl ethyl ketone)와 Toluene 제거 평가)

  • Jang, Duhun;Bae, Wookeun;Kim, Moonil;Kim, Kyungtae
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.6
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    • pp.31-37
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    • 2010
  • In this study, optimization of MEK and Toluene removal was conducted by HTO(Hybrid Thermal Oxidation) system. HTO system has a multi-bed reaction plate and the plate consisted of wasted heat regeneration part and catalysis part. VOCs removal by HTO system was estimated by changing inlet flow rates with different valve changing times. Under $350^{\circ}C$ of combustion temperature, VOCs was fully converted and the equivalent conversion was 100%. The thermal oxidation efficiency, related to the amount of injected fuel into HTO system and the valve change time, was revealed at the level of 93.0~96.3%. In case of MEK removal by HTO system, the efficiency was ranged from 91.1 to 97.1%. Also, Toluene removal efficiency(93.2~97.4%) was good and stable with respect to the operating conditions. Considering above results, it was proved that HTO system could be a stable and compact system for VOCs, especially MEK and Toluene with high removal efficiency.

Low-iridium Doped Single-crystalline Hydrogenated Titanates (H2Ti3O7) with Large Exposed {100} Facets for Enhanced Oxygen Evolution Reaction under Acidic Conditions ({100} 단결정 수소화 티타네이트(H2Ti3O7)를 활용한 저함량 Irridium 수전해 양극 촉매 개발)

  • Sun Young Jung;HyukSu Han
    • Journal of the Microelectronics and Packaging Society
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    • v.30 no.1
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    • pp.79-89
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    • 2023
  • Development of efficient and stable electrocatalysts for oxygen evolution reaction (OER) under acidic conditions is desirable goal for commercializing proton exchange membrane (PEM) water electroyzer. Herein, we report iridium-doped hydrogenated titanate (Ir-HTO) nanobelts as a promising catalyst with a low-Ir content for the acidic OER. Addition of low-Ir (~ 3.36 at%) into the single-crystalline HTO nanobelts with large exposed {100} facets significantly boost catalytic activity and stability for OER under acidic conditions. The Ir-HTO outperforms the commenrcial benchmark IrO2 catalyst; an overpotential for delivering 10 mA cm-2 current density was reduced to about 25% for the Ir-HTO. Moreover, the catalytic performance of Ir-HTO is positioned as the most efficient electrocatalyst for the acidic OER. An improved intrinsic catalytic activity and stability are also confirmed for the Ir-HTO through in-depth electrochemical characterizations. Therefore, our results suggest that low-Ir doped single-crystalline HTO nanobelts can be a promising catalyst for efficient and durable OER under acidic conditions.

TFWT and OBT Concentrations in Rice Plants Exposed to HTO Vapor during Daytime and Nighttime at Different Seed-Developing Stages (벼의 종실 발육단계에 따른 주간 및 야간 HTO 증기 피폭시 TFWT 및 OBT 농도)

  • Choi, Yong-Ho;Lim, Kwang-Muk;Lee, Won-Yun;Kang, Hee-Suk;Choi, Heui-Joo;Lee, Han-Soo;Diabate, Silvia;Strack, Siegfried
    • Journal of Radiation Protection and Research
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    • v.28 no.1
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    • pp.9-18
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    • 2003
  • Rice plants at different seed-developing stages were exposed to HTO vapor in an exposure box for 1 h during daytime and nighttime to investigate the levels of tissue free water $^3H$ (TFWT) and organically bound $^3H$ (OBT) in different plant parts. In the daytime experiment, TFWT concentrations in leaves at the end of exposure $(h_0)$ were around 100% of the 1 hour mean HTO concentrations in air moisture whereas in the nighttime experiment, they were as low as $30{\sim}40%$ of the air concentration. TFWT concentrations in both experiments decreased very rapidly in the beginning but much mote slowly later and those at harvest were hundreds to hundred thousands times lower than those at $h_0$. OBT concentrations varied with time in different manners depending on plant parts and exposure times and differed between at $h_0$ and at harvest by factors of less than 10 on the whole. Even during nighttime exposures, OBT was produced at about a third the rate for daytime exposures. The degree of the conversion of airborne HTO into OBT in mature rice seeds, being several times higher in the daytime experiment than in the nighttime experiment, was highest after the exposure peformed at the most actively seed-developing stage for both experiments. It is estimated that OBT would contribute much more to the ingestion radiation dose than TFWT if rice plants are exposed to HTO vapor for the seed-developing period.

TFWT and OBT Concentrations in Soybean Plants Exposed to HTO Vapor at Different Growth Stages (콩의 생육단계별 HTO 증기 피폭에 따른 작물체내 TFWT 및 OBT 농도)

  • Lim, K.M.;Choi, Y.H.;Lee, W.Y.;Park, H.G.;Kang, H.S.;Choi, H.J.;Lee, H.S.
    • Journal of Radiation Protection and Research
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    • v.29 no.4
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    • pp.213-219
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    • 2004
  • Soybean plants were exposed to HTO vapor in an exposure box for 1 hour at different growth stages. Relative concentrations of TFWT at the end of exposure (percent ratios of TFWT concentrations to mean HTO concentrations in air moisture in the box during exposure) decreased on the whole in the order of leaf > shell > seed > stem with the highest values of 40.2% and 6.4% for leaf and stem, respectively. TFWT concentrations reduced by factors of several thousands to several hundred-thousands from the end of exposure till the harvest. The reduction factor decreased in the order of leaf > shell > seed > stem. Relative OBT concentrations at harvest (ratios of the OBT concentration in the dry plant part at harvest to the initial leaf TFWT concentration, ml $g^{-1}$) were in the range of $2.2{\times}10^{-5}{\sim}9.5{\times}10^{-3}$ for seeds being the highest when the exposure was performed at the actively seed-developing stage. The exposure time-dependent variation in the OBT concentration was much greater in seeds and shells than in leaves and stems. It was indicated that OBT would contribute to almost all the radiation dose due to the consumption of soybean seeds in most cases after an acute exposure of growing plants to HTO vapor. Present results are applicable to establishing and validating soybean $^3H$ models for an acute accidental release of HTO.

Organically Bound Tritium in the Plants after Acute HTO Exposure (HTO 피폭후 식물의 조직결합수에 관한 연구)

  • Kim, Sang-Bog;Lee, Won-Yun;Choi, Young-Ho;Lee, Jeong-Ho
    • Journal of Radiation Protection and Research
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    • v.23 no.1
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    • pp.25-32
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    • 1998
  • Tritium is released into the environment as various form but HTO is most relevant to the incorporation of tritium into living organisms and to the formation of OBT. Tritiated compounds may be transported to humans via several tropic levels. Retention times of organically bound tritium in organisms are considerably longer than those of tritiated water, which has significant consequences on exposure dose estimation. It is rather difficult to predict the amount of OBT produced by the photosynthetic process of plants because it may be influenced by a multitude of environmental factors and plant parameters. Tritiated organic matters are classified as the exchangeable or nonexchangeable bound tritium according to the bound form. After short term HTO exposure in plants, the formation and uptake of OBT were evaluated.

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Properties of Poly-Si TFT's using Oxide-Nitride-Oxide Films as Gate Insulators (Oxide-Nitride-Oxide막을 게이트 절연막으로 사용하여 제조한 다결정실리콘 박막트랜지스티의 특성)

  • 이인찬;마대영
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.12
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    • pp.1065-1070
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    • 2003
  • HTO(High Temperature Oxide) films are mainly used as a gate insulator for polysilicon thin film transistors(Poly-Si TFT's). The HTO films, however, show the demerits of a high leakage current and a low electric breakdown voltage comparing with conventional thermal oxides even though they have a better surface in roughness than the thermal oxides. In this paper, we propose an ONO(Oxide-Nitride-Oxide) multilayer as the gate insulator for poly-Si TFT's. The leakage current and electric breakdown voltage of the ONO and HTO were measured. The drain current variation of poly-Si TFT's with a variety of gate insulators was observed. The thickness optimization in ONO films was carried out by studying I$\_$on/I$\_$off/ ratio of the poly-Si TFT's as a function of the thickness of ONO film adopted as gate insulator.