• Title/Summary/Keyword: volatile materials

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VOCs(Volatile Organic Compounds) sensor using SnO2 nanowires (산화주석 나노선을 이용한 VOCs 센서)

  • Hwang, In-Sung;Kim, Sun-Jung;Kim, Yoon-Sung;Ju, Byeong-Kwon;Lee, Jong-Heun
    • Journal of Sensor Science and Technology
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    • v.17 no.1
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    • pp.69-74
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    • 2008
  • VOCs (Volatile Organic Compound) sensors were fabricated using $SnO_2$nanowires-based thin films and its gas sensing behaviors were studied. The $SnO_2$ nanowires synthesized from a thermal evaporation process were dispersed in a solution and the sensor film was prepared by dropping the slurry on the substrate with the electrodes and an embedded heater. The gas response (Ra/Rg, Ra: resistance in air, Rg: resistance in gas) to $30{\sim}40$ ppm Benzene, Ethyl Benzene, o-xylene were in the range of $39{\sim}42$, which were significantly higher than those to 50 ppm of CO, $CH_4$ and $C_3H_8$ ($12{\sim}19$).

Non-volatile Control of 2DEG Conductance at Oxide Interfaces

  • Kim, Shin-Ik;Kim, Jin-Sang;Baek, Seung-Hyub
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.211.2-211.2
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    • 2014
  • Epitaxial complex oxide thin film heterostructures have attracted a great attention for their multifunctional properties, such as ferroelectricity, and ferromagnetism. Two dimensional electron gas (2DEG) confined at the interface between two insulating perovskite oxides such as LaAlO3/SrTiO3 interface, provides opportunities to expand various electronic and memory devices in nano-scale. Recently, it was reported that the conductivity of 2DEG could be controlled by external electric field. However, the switched conductivity of 2DEG was not stable with time, resulting in relaxation due to the reaction between charged surface on LaAlO3 layer and atmospheric conditions. In this report, we demonstrated a way to control the conductivity of 2DEG in non-volatile way integrating ferroelectric materials into LAO/STO heterostructure. We fabricated epitaxial Pb(Zr0.2Ti0.8)O3 films on LAO/STO heterostructure by pulsed laser deposition. The conductivity of 2DEG was reproducibly controlled with 3-order magnitude by switching the spontaneous polarization of PZT layer. The controlled conductivity was stable with time without relaxation over 60 hours. This is also consistent with robust polarization state of PZT layer confirmed by piezoresponse force microscopy. This work demonstrates a model system to combine ferroelectric material and 2DEG, which guides a way to realize novel multifunctional electronic devices.

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Effect of Viscous Materials Removal from Sea Tangle Extracts on Volatile Flavor Constituents (점성물질 제거가 다시마 추출액의 휘발성 향미성분에 미치는 영향)

  • Lee, Jung-Kun;Yoon, Suk-Kwon;Kim, Woo-Jung;Choi, Hee-Sook
    • Korean Journal of Food Science and Technology
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    • v.28 no.2
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    • pp.384-388
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    • 1996
  • Volatile flavor compounds of a sea tangle powder and two kinds of extract were analyzed by GC/MS. Extract I was prepared by boiling for 2 hours and centrifugation, while extract II by a sequential procedure of enzymatic hydrolysis, boiling in 1.5% NaCl solution. centrifugation and ultrafiltration to remove viscous materials. Fifty six volatile compounds from the dried sea tangle powder and the extracts were identified. The GC profiles of the extract II were different from those of the dried powder and the extract 1, indicating most volatile compounds were lost during removing viscous materials. Particularly those compounds in the initial and later parts of the GC profiles were significantly decreased and some of the compounds such as fatty acids. 3,5-nonadien-2-ol and 1-penton-3-ol were not detected.

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Volatile Flavor Components of Wild Chopi (Zanthoxylum piperitum De Candolle) Leaf (야생 초피(Zanthoxylum piperitum De Candolle)잎의 향기성분)

  • 박준희;차원섭;오상룡;조영제;이원영
    • The Korean Journal of Food And Nutrition
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    • v.13 no.5
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    • pp.483-489
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    • 2000
  • Wild Chopi leaves were harvested near Chounghwa Mt. Sangju city in Kyungpook province. Chopi leaves were dried naturally and crushed with and without blanching. From mechanical analysis(GC). fifty five peaks were identified as volatile materials in no blanching leaf. Among the fifty five peaks, twenty three peaks were identified as hydrocarbones(dodecane, sabinene, myrcene etc.), ten peaks as alcohols (isobutylalcohol. cis-pentenol, 1-pentenol, 1-penten-3-ol etc.), seven peaks as aldehydes (3-methylbua-tanal, hexanal, 2,6-dimethyl hept-5-al etc.), four peaks as ketones(3-hydroxy-2-butanone, 2-nonanone, 2-undecanone, 2-tridecanone) and six peaks as esters ( cis-3-hexenyl acetate, linalyl acetate. citronellyl acetate, nervy acetate etc.). Other peaks were founded as 3-cyano-2,5-dimethylpyrazine, dimethyl sulfide, chloroform, 1,8 cineole. Thirty five peaks were identified as volatile materials in blanching leaf. Twenty peaks were identified as hydrocarbones(1,1-oxybis-ethane, $\alpha$-pinene, camphene. myrcene, $\beta$-phellan-drene, $\beta$-caryophyllene etc.), as alcohol(L-linalool, (-)-isopulgerol, $\alpha$-terpineol. citronellol etc.), as aldehydes(nonanal, citronellal), as ketones(2-undecanone, 2-tridecanone etc.) and as esteres(citronellyl acetate. cis-3-hexenyl acetate, neryl acetate etc.). Other peaks were found as 3-cyano-2,5-dimethyl-pyrazine. The amount of volatile materials such as $\alpha$-pinene, myrcene, $\beta$-phellanderene, L-linalool, citronellal, citronellyl acetate, $\beta$-caryophyllene were detected abundantly among the volatile materials.

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An Reliable Non-Volatile Memory using Alloy Nano-Dots Layer with Extremely High Density

  • Lee, Gae-Hun;Kil, Gyu-Hyun;An, Ho-Joong;Song, Yun-Heup
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.02a
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    • pp.241-241
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    • 2010
  • New non-volatile memory with high density and high work-function metal nano-dots, MND (Metal Nano-Dot) memory, was proposed and fundamental characteristics of MND capacitor were evaluated. In this work, nano-dot layer of FePt with high density and high work-function (~5.2eV) was fabricated as a charge storage site in non-volatile memory, and its electrical characteristics were evaluated for the possibility of non-volatile memory in view of cell operation by Fowler-Nordheim (FN)-tunneling. Here, nano-dot FePt layer was controlled as a uniform single layer with dot size of under ~ 2nm and dot density of ${\sim}\;1.2{\times}10^{13}/cm^2$. Electrical measurements of MOS structure with FePt nano-dot layer shows threshold voltage window of ~ 6V using FN programming and erasing, which is satisfied with operation of the non-volatile memory. Furthermore, this structure provides better data retention characteristics compared to other metal dot materials with the similar dot density in our experiments. From these results, it is expected that this non-volatile memory using FePt nano-dot layer with high dot density and high work-function can be one of candidate structures for the future non-volatile memory.

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Emission Characteristics of Volatile Organic Compounds from the Interior Materials of Railroad Rolling Stocks (철도차량 내장재에서의 VOCs 방출 특성)

  • Park Duck-Shin;Cho Young-min
    • Proceedings of the KSR Conference
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    • 2004.06a
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    • pp.235-240
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    • 2004
  • The aim of this study is to investigate the emission characteristics of volatile organic compounds from the interior materials of railroad rolling stock. Samples for VOCs were collected using a environmental chamber and the samples were analyzed for 35 individual compounds. 6 different types of materials, seat cover and flour material of Mugunghwaho, Saemaeulho and electric rolling stock were analysed. The results were expressed as concentrations over 12, 18, 24, 36 and 48 hours. VOCs concentrations were measured to be higher in the 12 hours than in the 48 hours. Floor material of Mugunghwaho showed the highest concentration of all studied materials. Followed by floor materials of Saemaeulho and electric rolling stock.

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Effect of Physicochemical Properties of Solvents on Microstructure of Conducting Polymer Film for Non-Volatile Polymer Memory

  • Paik, Un-Gyu;Lee, Sang-Kyu;Park, Jea-Gun
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.8 no.1
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    • pp.46-50
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    • 2008
  • The effect of physicochemical properties of solvents on the microstructure of polyvinyl carbazole (PVK) film for non-volatile polymer memory was investigated. For the solubilization of PVK molecules and the preparation of PVK films, four solvents with different physicochemical properties of the Hildebrand solubility parameter and vapor pressure were considered: chloroform, tetrahydrofuran (THF), 1,1,2,2-tetrachloroethane (TCE), and N,N-dimehtylformamide (DMF). The solubility of PVK molecules in the solvents was observed by ultravioletvisible spectroscopy. PVK molecules were observed to be more soluble in chloroform, with a low Hildebrand solubility parameter, than solvents with higher values. The aggregated size and micro-/nano-topographical properties of PVK films were characterized using optical and atomic force microscopes. The PVK film cast from chloroform exhibited enhanced surface roughness compared to that from TCE and DMF. It was also confirmed that the microstructure of PVK film has an effect on the performance of non-volatile polymer memory.

Changes of Korean Traditional Yu-gwa Flavor and Characteristics during Storage (유과의 저장기간에 따른 휘발성 향미성분 및 특성 분석)

  • Yoo, Seung-Seok
    • Journal of the Korean Society of Food Culture
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    • v.22 no.1
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    • pp.83-90
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    • 2007
  • The changes of the color, texture and volatile flavor compounds of Yu-gwa were investigated that affected by the oxidation during storage to characteristic Yu-gwa quality. Among the proximate compositions, carbohydrate was the most abundant component, and followed by lipid and moisture. Although the change of the color showed different pattern by the packaging materials during the storage period, the value of yellowness(b) increased but that of lightness(L) decreased dramatically after 3 month storage. In the textural properties reported closely related with the moisture content, hardness was fairly affected on the period of the storage rather than the type of packaging materials. The flavor compounds of Yu-gwa were analyzed to evaluate the change of distinct volatile compounds during storage. Of the twenty one separated volatile compounds, major volatiles were aldehydes, alcohols and alkenes. The results also showed that polyethylene(PE) contained less volatiles than polypropylene(PP) by the oxidation process during storage.2,4-Decadienal was gradually increased with the period of the storage, whereas octane and furan were decreased. The results provided that the change of the flavor distribution during the storage, and also the possibility of the volatiles such as hexanal, nonanal and 2,4-decadienal as the indicator for the oxidation process.

The utilization of fungicide and insecticide from medicinal plants for conservation of cultural properties (천연약재로부터 문화재보존용 방충방균제 개발연구)

  • Chung, Yong-Jae;Lee, Kyu-Shik;Han, Sung-Hee;Kang, Dai-Ill;Lee, Myeong-Hui
    • 보존과학연구
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    • s.22
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    • pp.5-25
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    • 2001
  • The germicidal and insecticidal properties of volatile components extracted from star anise(Illicium verum Hooker filius) and clove (Eugenia caryophyllata THUNBERG)were evaluated against five microorganisms and three insects for the purpose of developing biocidal active substances from medicinal plants. The volatile components of star anise and clove showed strong antimicrobial effect against Aspergillus niger, Penicillium funiculosum, Mucor hiemalis, Trichoderma viride, and Aureobasidium pullulans. The extracts of each medicine also showed insecticidal effects against Sitophilusoryzae L., Lyctus linearis GOZE, and Reticulitermes spertus kyushuensis Morimoto. Fumigant toxicities to adult insects were determined. In the case of fumiganttoxicity, the extract of star anise showed 100% mortality against R. spertus, S.oryzae, and L. linearis at rates of $2.5\mu\ell$, $50\mu\ell$, $250\mu\ell$/filter paper, respectively but showed no killing effects by clove. The volatile components of star anise and clove were investigated by means of GC/MS. The main constitute, anethole among 20components from star anise and eugenol among 9 components from clove were identified. The mixture of star anise and clove as the volume ratio of 2 : 1 showed higher properties for antimicrobial and insecticidal effect than each volatile component. A. niger was inhibited by the mixture(125ml/$m^3$) for up to 10 days of exposure. Also, from the result of observing state change of organic materials by volatile extracts of star anise and clove, volatile extracts effects have no effect on natural organic materials of organic cultural properties and can be used as biological control agent. As research contents as above, the insecticidal and germicidal agents from star anise and clove and the mixture of them were more efficient and high level to prevent biological damage for conservation of organic cultural properties. So they may be used in new development of biologicalinsecticidal and germicidal agents for conservation of cultural properties.

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Characteristics of TVOCs Emission Factors from Chemical and Natural Coating Materials (화학 및 천연페인트에서 발생되는 TVOCs의 방출강도 특성 연구)

  • Kim Shin Do;Kim Jeong Ho;Park Jin Soo;Lee Jeong Joo
    • Journal of Environmental Health Sciences
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    • v.30 no.5 s.81
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    • pp.487-492
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    • 2004
  • Building materials are composed of very complex chemical compounds, and these indoor building materials discharge very much Volatile Organic Compounds(VOCs). We performed the environmental chamber test to investigate the Total VOCs(TVOCs) emission characteristics and emission factors about chemical and natural coating materials. As the result, we concluded that TVOCs emission are high at initial time and decreased in course of time. Natural paint was low emission level for TVOCs than chemical paint by small chamber test. The TVOCs emission factor-time profile showed a good fit with the results from the measured and predicted value.