• Korean Journal of Materials Research
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• v.23 no.4
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• pp.211-214
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• 2013

The effects of a Ni coating on the sensing properties of nano ZnO:Ni based gas sensors were studied for $CH_4$ and $CH_3CH_2CH_3$ gases. Nano ZnO sensing materials were prepared by the hydrothermal reaction method. The Ni coatings on the nano ZnO surface were deposited by the hydrolysis of zinc chloride with $NH_4OH$. The weight % of Ni coating on the ZnO surface ranged from 0 to 10 %. The nano ZnO:Ni gas sensors were fabricated by a screen printing method on alumina substrates. The structural and morphological properties of the nano ZnO : Ni sensing materials were investigated by XRD, EDS, and SEM. The XRD patterns showed that nano ZnO : Ni powders with a wurtzite structure were grown with (1 0 0), (0 0 2), and (1 0 1) dominant peaks. The particle size of nano ZnO powders was about 250 nm. The sensitivity of nano ZnO:Ni based sensors for 5 ppm $CH_4$ gas and $CH_3CH_2CH_3$ gas was measured at room temperature by comparing the resistance in air with that in target gases. The highest sensitivity of the ZnO:Ni sensor to $CH_4$ gas and $CH_3CH_2CH_3$ gas was observed at Ni 4 wt%. The response and recovery times of 4 wt% Ni coated ZnO:Ni gas sensors were 14 s and 15 s, respectively.

• Korean journal of food and cookery science
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• v.31 no.4
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• pp.405-412
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• 2015

To develop a color stable and fine bamboo leaf powder (BLP) as a functional green biomaterial, bamboo leaf (BL) purchased from Sasa borealis and cultivated in Damyang, Jeonnam was treated with different conditions and BLP was evaluated. The four treatments comprised of boiling in water, in zinc chloride, sodium bicarbonate, and vinegar solutions, BLP4 was treated with 2% $ZnCl_2$ for 1 h, BLP5 was treated with 1% $ZnCl_2$ for 2 h, and BLP6 was treated with 1% $ZnCl_2+10%$ NaCl for 1 h. The particle size distribution, ash content, water binding capacity, and color change after heating in acidic solution were compared to commercial fine green tea (GTP) and bamboo leaf powders (CBLP). The particle size (cumulative 90%) of BLP was finest in BLP4 followed by BLP6 < BLP5 < GTP < CBLP. The water binding capacity of GTP was the highest and that of BLP was negatively correlated with particle size. After heating in acidic solution, the color of commercial GTP and CBLP changed from bright green to olive green, but the treated BLPs remained bright green. Especially, the -a (greenness) values for the commercial powders decreased from 11.2-13.6 to 3.1-3.8, while those of the treated BLPs did not change.

• Journal of the Korean Ceramic Society
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• v.33 no.2
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• pp.149-154
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• 1996

ZnO and Al-doped ZnO thin films were prepared by sol-gel dip-coating method and electrical and optical properties of films were investigated. Using the zinc acetate dihydrate and acetylaceton(AcAc) as a chelating agent stable ZnO sol was synthesized with HCl catalyst. Adding aluminium chloride to the ZnO sol Al-doped ZnO sol could be also synthesized. As Al contents increase the crystallinity of ZnO thin film was retarded by increased compressive stress in the film resulted from the difference of ionic radius between Zn2+ and Al3+ The thickness of ZnO and Al-doped ZnO thin film was in the range of 2100~2350$\AA$. The resistivity of ZnO thin films was measured by Van der Pauw method. ZnO and Al-doped ZnO thin films with annealing temperature and Al content had the resistivity of 0.78~1.65$\Omega$cm and ZnO and Al-doped ZnO thin film post-annealed at 40$0^{\circ}C$ in vacuum(5$\times$10-5 torr) showed the resistivity of 2.28$\times$10-2$\Omega$cm. And the trans-mittance of ZnO and Al-doped ZnO thin film is in the range of 91-97% in visible range.

• Journal of the Korean Chemical Society
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• v.38 no.9
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• pp.676-681
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• 1994

Diels-Alder adducts, carbacephems were obtained when 4-acetoxyazetidine-2-one or (3R,4R)-4-acetoxy-3-[(1R)-1-(tert-butyldimethylsilyloxy)ethyl]azetidin-2-one was reacted with 2-(tert-butyldimethylsilyloxy)-1,3-butadiene or with 3-(tert-butyldimethylsilyloxy)-1,3-pentadiene. When tert-butyldiemethylsilyl acrylate was used as the diene, products in which was acetoxy group of 4-acetoxyazetidin-2-one derivatives was substituted by an acryloyloxy group were isolated. When the same reaction was carried out with 4-phenylsulfonylazetidin-2-one as a dienophile with 2-(tert-butyldimethylsilyloxy)-1,3-butadiene, 4-phenylsulfoyl-2-butanone was obtained instead of the expected carbacephem. When dimeric form of thiochalcone was reacted with 4-acetoxyazetidin-2-one in the presence of zinc chloride, the $\beta-lactam$ ring of the azetidin-2-one was destructed and no product was isolated. Also, the reaction of 2-trimethylsilyloxy-1-aza-1,3-butadiene, which was obtained from N-methylacrylamide by treatment of trimethylsilyl trifluoromethanesulfonate in the presence of triethylamine, with 4-acetoxyazetidin-2-one did not give any products.

• The Korean Journal of Zoology
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• v.31 no.3
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• pp.157-164
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• 1988

SCK tumor cells were exposed to heat shock or several sulihydryl-reacting agents such as iodoacetamide(IAA), zinc chloride(Zn), and 2-mercaptoethanol(ME). Stress proteins induced by these agents were examined and the relationship between the induction of stress proteins and the production of abnormal proteins was discussed. Based on the present experiments, two classes of intracellular pathways for the induction of stress proteins were defined; one dependent on and the other independent of protein synthesis. The presence of cycloheximide during the induction period blocked the formation of stress proteins in the cells exposed to Zn or ME, but not in those exposed to heat shock or IAA.Therefore, stress protein seems to be induced either by denaturation of pre-existing mature proteins (e.g., heat shock or IAA) or by newly synthesized abnormal proteins(e.g., Zn or ME). In conclusion, it is ilkely that the production of abnormal proteins by stresses triggers stress protein induction. In addition, it was found that the cells exposed to IISP and GRP inducers simultaneously responded to more strong stress among several stresses encountered.

• Journal of the Korean Society of Food Culture
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• v.29 no.2
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• pp.212-221
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• 2014

Korean style DASH (Dietary Approaches to Stop Hypertension) and a dietary education program for sodium reduction were developed. Reduced sodium diets (15 and 30% reductions) were developed from general diets for 3 consecutive weeks from Monday through Saturday. Subjects (19 total) were classified into two groups according to dietary education. Experimental period was from June 24 to July 23, 2012. Total sum of adaptation scores for low sodium diets significantly increased in the group that underwent dietary education compared to that without (p<0.05). After the experiment, both groups showed significantly increased values in terms of food group balance, sodium-related nutrition knowledge, attitude, and practice by paired t-test. Especially, group that underwent dietary education showed significantly higher values for attitudes by ANCOVA pre-test as a variation (p<0.01). For the results of the nutrient intake survey, group that underwent dietary education showed significantly increased values for dietary fiber (p<0.01), vitamin A (p<0.001), vitamin K (p<0.001), vitamin C (p<0.01), Folic acid (p<0.001), vitamin B12 (p<0.01), calcium (p<0.01), iron (p<0.05), and zinc (p<0.05) and significantly decreased values for sodium (p<0.05) and chloride (p<0.005). Subjects adapted to reduced sodium diets showed apparent improvements in sodium-related knowledge, attitude, practice and intake of nutrient, and these improvements were even higher in the group that underwent dietary education compared to that without. Thus, adaptation to low sodium diet combined with dietary education can improve dietary habits.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.13-21
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• 1992

The inhibitory effects of mercury ions on the growth of barley seedlings were studied and the distribution of metal elements in the organs of treated plants was investigated by using synchrotron radiation induced X-ray emission (SRIXE). Although the treatment of mercury ions caused growth inhibition, the mercury-specific increase in variable fluorescence and the abolishment of energy-dependent quenching in broken barley chloroplasts as shown by Moon et at. (1992) were not observed in the leaves of growth-inhibited seedlings. Instead the treatment of mercury decreased Fmax and Fo values. However, Fmax/Fo ratio and photochemical and nonphotochemical quenching coefficients were not affected significantly. By SRIXE analysis of $10\mu\textrm{m}$ mercury chloride treated seedlings, accumulation of mercury in roots was observed after 1 hour of treatment and similar concentration was sustained for 48 hours. Relative contents of mercury was high in roots and underground nodes where seeds were attachedl but was very low in leaves. Iron and zinc were also distributed mainly in the lower parts of the seedlings. However after 72 hours of treatment the contents of these metals in roots decreased and their distribution became more uniform, which may lead to death of the plants. These results suggest that the observed inhibitory effects on barley seedlings upto 48 hours after the treatment is not due to direct damages in the photosynthetic apparatus, but due to its accumulation in roots and the consequent retardation of the growth of barley seedlings. The decrease in Fmax and Fo is probably due to the decrease in chlorophyll and protein contents caused by the retardation of growth. The observed slow expansion of primary leaves could be also explained by the retardation of growth, but the fluorescence induction pattern from the leaves did not show characteristic symptoms of leaves under water stress.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.347-351
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• 2013

The preparation of glycerol carbonate (GC) from urea through carbonylation with renewable glycerol was investigated by using ionic liquid catalysts. It was found that quaternary ammonium salt and imidazolium salt ionic liquids with a shorter alkyl chain length and higher nucleophilic anion showed better catalytic performance. The effects of reaction temperature, reaction time and degree of vacuum on the reactivity of TBAC catalyst ware discussed. Zinc chloride ($ZnCl_2$) was used as co-catalyst with the ionic liquid catalyst. The mixed catalyst showed a synergy effect on the glycerol conversion and GC yield probably due to the acid-base properties of the catalysts.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.6
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• pp.673-682
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• 2016

In this study, we investigated influent and effluent water pollutants in 53 Public Sewage Treatment Works (PSTWs) where industrial wastewater or landfill leachate is combined four times for two years from 2014 to 2015. Also, we analyzed the characteristics of heavy metals and volatile organic carbons at influent and effluent of these PSTWs caused by sewage treatment combined with industrial wastewater or landfill leachate. As a result, six heavy metals such as barium, copper, iron, manganese, nickel and zinc, and four volatile organic carbons (VOCs) including phenols, di(2-)ethylhexyl phthalate (DEHP), formaldehyde and toluene were observed above detection limits in most of PSTWs. Also, it was revealed that six heavy metals such as hexavalent chromium, mercury, cadmium, chromium, nickel and selenium, and four VOCs including 1,1-dichloroethylene, vinyl chloride, naphthalene, and epichlorohydrin were observed more frequently according to precipitation. As a result of reviewing the monitoring data on "Water Quality Monitoring Networks" in lower watersheds of PSTWs, both heavy metals and VOCs were below detection limits, indicating that the effluent water had little influence on the watershed. Nevertheless for the better management of influent and effluent pollutants in PSTWs, it is necessary to establish the advanced management plans for water pollutants in PSTWs, which include a list of priority substances management, monitoring plans, and guidelines for industrial wastewater and landfill leachate combined in PSTWs.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.262.1-262.1
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• 2013

ZnO 나노구조는 전기적 성질과 화학적인 안정성 때문에 가스센서, 투명 전극 및 태양전지와 같은 전자소자와 광소자에 널리 사용되고 있다. ZnO 박막을 증착하는 방법은 Physical Vapor Deposition과 Chemical Vapor Deposition이 있으나 나노 구조를 가진 SnO2를 형성하기 어렵다. 전기 화학적 증착(Electrochemical Deposition: ECD)은 낮은 온도에서 진공 공정이 필요하지 않기 때문에 경제적이며 빠른 성장 속도를 가지고 있기 때문에 ZnO 나노 구조를 효과적으로 형성 할 수 있다. 본 연구에서는 Indium Tin Oxide (ITO) 기판 위에 ZnO 나노 구조를 형성시켜 전기적 및 구조적 특성을 관찰하였다. 0.1 M zinc nitrate와 0.1 M potassium chloride를 용매에 각각 용해하여 ZnO 나노구조를 성장하였다. ZnO 나노구조를 성장하기 위하여 인가전압을 -0.75 V부터 -2.5 V까지 0.5 V 간격으로 변화하였다. X-선 회절 분석결과에서 ZnO의 피크의 크기가 큰 전기화적적 성장 전압구간과, 주사전자현미경 분석결과에서 나노 구조가 가장 잘 나타난 성장 전압구간을 다시 0.1 V 간격으로 세분화하여 최적화 조건을 분석하였다. X-선 회절 실험으로 형성한 ZnO 나노구조의 피크가 (110) (002)로 나타났다. X-선 회절 분석의 intensity의 값이 (002)방향이 가장 크게 나타났으므로 우선적으로 (002) 방향으로 ZnO 나노구조가 성장됨을 알 수 있었다. 주사전자현미경상은 grain size가 200~300 nm 사이의 ZnO 나노구조가 형성되며, grain size가 전기화학적 증착 장치의 성장전압이 커짐에 따라 커지는 것을 알 수 있었다.