• Title/Summary/Keyword: zinc

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Effect of Ga-doping on the properties of ZnO films grown on glass substrate at room temperature by radio frequency magnetron sputtering (RF 마그네트론 스퍼터링 방법으로 상온에서 유리기판 위에 성장시킨 ZnO의 성질에 미치는 Ga 도핑 효과)

  • Kim, G.C.;Lee, J.S.;Lee, S.K.;Kim, D.H.;Lee, S.H.;Moon, J.H.;Jeon, M.H.
    • Journal of the Korean Vacuum Society
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    • v.17 no.1
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    • pp.40-45
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    • 2008
  • We present the effect of Ga-doping on the electrical, structural and optical properties of ZnO layers with a thickness of ${\sim}500nm$ deposited on glass substrates. Polycrystalline ZnO and Ga-doped ZnO (GZO) layers were deposited by radio frequency (rf) magnetron sputtering at room temperature. Based on the X-ray diffraction (XRD) and transmission electron microscopy (TEM) data, the crystalline quality of Ga-doped ZnO film was improved and GZO film has a preferred orientation along with the (002) crystal direction. The transmittance of the GZO film was enhanced by 10% in the visible region from that of the ZnO film. From photoluminescence (PL) data, the ratio of intensity of near band edge (NBE) emission to deep level (DL) emission was as high as 2.65:1 and 1.27:1 in the GZO and ZnO films, respectively. The res istivities of GZO and ZnO films were measured to be 1.27 and 1.61 $\Omega{\cdot}cm$, respectively. The carrier concentrations of ZnO and GZO film were approximately 1018 and 1020 $cm^2$/Vs, respectively. Based on our experimental results, the Ga-doping improves the electrical, structural and optical properties of ZnO film with potential application.

이종 타겟을 지닌 대향 타겟 스퍼터링 방법으로 제작된 AZO 박막의 광학적·전기적 특성에 관한 연구

  • ;Seo, Seong-Bo;Bae, Gang;Kim, Dong-Yeong;Choe, Myeong-Gyu;Kim, Hwa-Min
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.337-337
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    • 2014
  • 투명 전도성 산화물(transparent conductive oxide: TCO) 박막은 높은 투과율과 낮은 비저항 덕분에 LCD (liquid crystal display), PDP (plasma display panel), OLED (organic light emitting display) 등 평판 디스플레이에 널리 사용되고 있다. 현재 양산되고 있는 ITO (indium tin oxide)는 90% 이상의 높은 투과율과 우수한 전도성으로 인해 TCO 박막 가운데서 디스플레이 산업에서 가장 널리 쓰이고 있다. 그런데, ITO의 인듐산화물에 의한 간질성 폐렴(interstitial pneumonia)의 유발 위험이 있다든가, 인듐의 매장량이 적어 원자재 가격이 비싼 단점도 가지고 있다. 이에 최근 ITO를 대체할 수 있는 TCO물질로 많은 연구가 이루어지고 있는데, 특히 AZO (aluminum-doped zinc oxide)는 그 중 대표적인 대체물질로서 독성이 없고 가격도 저렴하여 많은 관심이 증폭되고 있다. 현재 AZO는 sol-gel 방법이나 CVD (chemical vapor deposition) 또는 스퍼터링 방법 등으로 증착되고 있다. 본 연구에서는 두 개의 이종타겟(hetero target)을 장착한 대향 타겟 스퍼터링(facing target sputtering: FTS) 장치를 사용하여 AZO 박막을 제작한다. 기존의 여러 증착법과 달리, FTS 장치는 두 타겟 사이에 형성되는 플라즈마 내의 ${\gamma}$-전자를 구속하게 되며, 낮은 가스 압력에서 고밀도 플라즈마가 생성되어 빠른 증착 속도와 안정적인 방전을 유지한 상태에서 박막을 증착할 수가 있다. 또한 기판과 플라즈마가 이격되어 있어 높은 에너지를 갖는 입자들의 기판 충돌을 억제할 수 있는 장점들을 갖는다. 이종 타겟인 ZnO와 Al2O3를 사용하고 각 타겟에 인가되는 파워 변화를 통해 AZO 박막 내 Al2O3의 성분비를 조절하였다. ZnO 타겟의 증착 파워를 100 W로 고정할 경우, Al2O3 타겟의 증착 파워가 (50~90) W으로 실험을 하였으며, Al2O3 타겟의 증착 파워가 70 W일 때 AZO 박막의 Al2O3 성분비는 2.02 wt.%이며 박막의 비저항 값은 $5{\times}10^{-4}{\Omega}{\cdot}cm$로 최소값을 보였다. 이러한 비저항의 변화는 파워에 따른 AZO 박막의 캐리어 이동도(Hall mobility)와 캐리어의 농도(Carrier Concentration)의 변화와 밀접한 관계가 있음을 보여주며, 특히 AZO 박막의 캐리어 농도와 캐리어 이동도는 AZO 박막을 형성하고 있는 결정립의 크기에 의존하는 것이 X-선 회절 패턴과 SEM으로부터 확인되었다. 특히, 본 연구에서는 두 개의 이종 타겟(hetero target) Al2O3와 ZnO를 장착하고 각각의 파워를 변화시켜 도핑 량을 조절할 수는 대향 타겟 스퍼터링(FTS: facing-target sputtering) 방법을 이용하여 제작된 AZO 박막에 대해 전기적, 광학적 및 구조적 특성을 분석하고 ITO의 대체물로서의 가능성을 검토하고자 한다.

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A Study of Material and Production Technique of Scroll Painting Ring in Joseon (조선시대 족자 장황에 사용된 고리의 재료 및 제작기법 연구)

  • Jang, Yeonhee;Yun, Eunyoung;Kwon, Yoonmi;Kim, Sooyeon
    • Conservation Science in Museum
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    • v.16
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    • pp.56-81
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    • 2015
  • Ring in the scroll painting is one of the mounting elements which are fixed string and tassel to hang, these differ widely in shape and produce a variety of metals. Most traditional shapes of ring have been lost, because of remount, there are used Japanese style rings in present.Therefore, this study examines to shape, production technique and analyze component traditional style rings of 19 traditional scroll paintings in National Museum of Korea for restoration of original style. Ring has been recorded official names; Wonhwan(Ring), Gukhwadong(Chrysanthemum shaped ornaments), Baemok(Ring-shaped nail) in Uigwe. Result of an optical microscope (Leica, M205A), Wonhwan has two type of production technique; one is cutting and bending a metal rod and other is cast. Baemok is made to forging process after metal rod or plate by casting alloy. Baemok decoration is metal plate cutting shape, and then decorates it with pattern by using kicking line engraving, chasing and so on. Component analysis result from portable X-ray fluorescence found various metals, such as, brass, iron silver-cooper. Brass based on copper and zinc used rings of 17 scroll painting. Baemok of Yun Sidal portrait is used iron and plated with a tin-lead alloy. Yi Seogu portrait is silver-cooper alloy in whole ring.

Effects of Growth Conditions on Properties of ZnO Nanostructures Grown by Hydrothermal Method (수열합성법으로 성장된 ZnO 나노구조의 성장조건에 따른 특성)

  • Cho, Min-Young;Kim, Min-Su;Kim, Ghun-Sik;Choi, Hyun-Young;Jeon, Su-Min;Yim, Kwang-Gug;Lee, Dong-Yul;Kim, Jin-Soo;Kim, Jong-Su;Lee, Joo-In;Leem, Jae-Young
    • Korean Journal of Materials Research
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    • v.20 no.5
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    • pp.262-266
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    • 2010
  • ZnO nanostructures were grown on an Au seed layer by a hydrothermal method. The Au seed layer was deposited by ion sputter on a Si (100) substrate, and then the ZnO nanostructures were grown with different precursor concentrations ranging from 0.01 M to 0.3M at $150^{\circ}C$ and different growth temperatures ranging from $100^{\circ}C$ to $250^{\circ}C$ with 0.3 M of precursor concentration. FE-SEM (field-emission scanning electron microscopy), XRD (X-ray diffraction), and PL (photoluminescence) were carried out to investigate the structural and optical properties of the ZnO nanostructures. The different morphologies are shown with different growth conditions by FE-SEM images. The density of the ZnO nanostructures changed significantly as the growth conditions changed. The density increased as the precursor concentration increased. The ZnO nanostructures are barely grown at $100^{\circ}C$ and the ZnO nanostructure grown at $150^{\circ}C$ has the highest density. The XRD pattern shows the ZnO (100), ZnO (002), ZnO (101) peaks, which indicated the ZnO structure has a wurtzite structure. The higher intensity and lower FWHM (full width at half maximum) of the ZnO peaks were observed at a growth temperature of $150^{\circ}C$, which indicated higher crystal quality. A near band edge emission (NBE) and a deep level emission (DLE) were observed at the PL spectra and the intensity of the DLE increased as the density of the ZnO nanostructures increased.

Geology and Mineralization in Hidalgo State, Mexico (멕시코 이달고주의 지질 및 광화작용)

  • Oh, Il-Hwan;Heo, Chul-Ho
    • Journal of the Mineralogical Society of Korea
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    • v.31 no.1
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    • pp.57-65
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    • 2018
  • The geology of Hidalgo state in Mexico is formed by a Precambrian metamorphic rock base which discordantly supports a strong Paleozoic sedimentary rock sequence. Triassic-Jurassic and Cretaceous sedimentary rocks overlie the above-mentioned rocks at a discordant angle. These Mesozoic rocks are in turn covered by a Cenozoic structure which is marine at its base. At the top, the structure changes to andesitic and basaltic composition volcanic rocks. And, a great variety of mineral deposits, both metallic and nonmetallic, is present in Hidalgo state. The host rocks of these deposits are also very varied in age from Mesozoic to Tertiary. Mineralization age corresponds to Tertiary in 90% of the area. Hidalgo state occupies as an important place in national silver and manganese production. Main mineral deposits correspond to argentiferous veins hosted in sedimentary rocks. Following in order of importance are lead and zinc, as well as some small iron deposits. There is evidence of tin and molybdenum mineralization, but these deposits have not been exploited because of their low grade and volume. And, Hidalgo state has different types of nonmetallic mineral deposits such as sedimentary, hydrothermal, metamorphic and volcanic origins.

Spectral Characteristics of Heavy Metal Contaminated Soils in the Vicinity of Boksu Mine (복수광산 주변 중금속 오염 토양의 분광학적 특성)

  • Shin, Ji Hye;Yu, Jaehyung;Jeong, Yong Sik;Kim, Seyoung;Koh, Sang-Mo;Park, Gyesoon
    • Journal of the Mineralogical Society of Korea
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    • v.29 no.3
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    • pp.89-101
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    • 2016
  • This study investigated spectral characteristics of heavy metal contaminated soil samples in the vicinity of abandoned Boksu mine. Heavy metal concentrations including arsenic, lead, zinc, copper and cadmium were analyzed by XRF analysis. As a result, all of the soil samples excluding control sample were over-contaminated based on the counter measure standard. The XRD results revealed that quartz, kaolinite and smectite were detected for all of the soil samples and heavy metals in soil were adsorbed on clay minerals such as kaolinite and smectite. The spectral analyses confirmed that spectral reflectance of near-infrared and shorter portion of shortwave-infrared spectrum decreases as heavy metal concentration increases. Moreover, absorption depths at 2312 nm and 2380 nm, the absorption features of clay minerals, decreases with higher heavy metal concentration indicating adsorption of heavy metal ions with clay minerals. It indicates that spectral features and heavy metal contamination of soil samples have high correlations.

Production of PBT(polybutylene terephthalate) Oligomer from Recycled PET(polyethylene terephthalate) (재활용 PET(polyethylene terephthalate)를 이용한 PBT(polybutylene terephthalate) 올리고머 제조)

  • Cho, Minjeong;Yang, Jeongin;Noh, Seunghyun;Joe, Hongjae;Han, Myungwan
    • Korean Chemical Engineering Research
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    • v.54 no.4
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    • pp.437-442
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    • 2016
  • A new route for PBT (Poly butylene terephthalate) production from recycled PET (Poly ethylene terephthalate) has been explored. The route consists of glycolysis of PET (Poly ethylene terephthalate) wastes using 1,4-butandiol into BHBT oligomers and polycondensation of the oligomers into PBT oligomer. This process uses post-consumer or post-industrial recycled PET and converts it into high-end PBT type engineering thermoplastic via a chemical recycling process. Zink acetate was used as a catalyst for both glycolysis and polycondensation. Two types of reactor for the glycolysis, batch and semi-batch reactor, were investigated and their performances were compared. Semi-batch reactor removes ethylene glycol (EG) and THF (tetrahydrofuran) during the reaction. Amounts of EG and THF generated during the glycolysis reaction were measured and used as criteria for the reactor performance. Performance of semi-batch reactor was shown to be better than that of batch reactor. Optimum reaction condition for the semi-batch reactor was BD/PET ratio of 4, and reaction temperature of $220^{\circ}C$, giving high EG yield (max 91%) and low production of THF. In addition, it was confirmed that the molecular weight of PBT oligomer increases in accordance with the progress of the polycondensation reaction.

Trace Metal Contents in Fishes and Shellfishes and Their Safety Evaluatins (우리나라 어패류중 미량금속 함량 및 안전성 평가)

  • 소유섭;김정수;정소영;김미혜;홍무기
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.29 no.4
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    • pp.549-554
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    • 2000
  • This study was carried out to estimate the contents of trace metals in the fishes and shellfishes available on Korean markets. The maples were digested with acids, then analyzed by ICP (INductively Coupled Plasma Spectrometer) and AAS (Atomic Absorption Spectrometer) for the contents of lead (Pb), cadmium (Cd), arsenic (As), copper (Cu), manganese (Mn) and zinc (Zn). The contents of mercury (Hg) were determined using a mercury analyzer. The contents of trace metals [minimum~ maximum (mean), mg/kg] in fishes were as follows; Hg;0.004~0.500(0.082), Pb;N.D.~ 1.87 (0.29), Cd;N.D. ~0.094 (0.020), As;0.01~5045 (0.84), Cu;0.04~3.74 (0.66), Mn; N.D. ~7.56 (0.57), Zn;0.92~18.33(6.03). Those contents in shellfishes were as follows (mg/kg); Hg;N.D.~0.221 (0.029), Pb;0.01~1.51 (0.38), Cd;0.02~1.93 (0.51), As;0.18~3.07 study showed that trace metal contents in both fishes and shellfishes on our markets of lead, cadmium and mercury from fishes and shellfishes takes about 1~13% of PTWI(Provisional Tolerable Weekly Intakes) that FAO/WHO Joint Food Additive and Contaminants Committee has set to evaluate their safeties.

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Effect of 12-week Low Calorie Diet and Behavior Modification on the Anthropomeric Indices and Biochemical Nutritional Status of Obese Woman (12주 동안의 저열량식사와 행동수정요법이 비만여성의 체격지수와 생화학적 영양상태에 미치는 영향)

  • Son, Sook-Mee;Kim, Hee-Jun
    • Korean Journal of Community Nutrition
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    • v.10 no.4
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    • pp.525-535
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    • 2005
  • This study was conducted to investigate the effect of a 3 week low calorie diet (LCD) and a 9 week of behavior modification (BM) program on the weight loss, mineral and vitamin status in 22 obese women. The subject were healthy, obese (PIBW> $120\%$) women aged 20 - 50 Yr and not taking any medications known to influence body composition, mineral or vitamin metabolism During the LCD program, subjects were provided commercial liquid formulas with 125 kcal per pack and were instructed to have a formula for replacement of one meal and at least one regular meal per day within the range of daily 800 - 1200 kcal intake. During the BM program the subjects weekly attended the group nutrition counseling session to encourage themselves to modify their eating behavior and spontaneously restrict their energy intakes. The BM program focused on stimulus control, control of portion sizes and modification of binge eating and other adverse habits. The initial mean energy intake of subjects was 2016.9 $\pm$ 129.8 kcal ($100.8\%$ of RDA) and dropped to 1276.5 $\pm$ 435.7 kcal at the end of a 3 week of LCD program and elevated to 1762 $\pm$ 329.3 kcal at the end of a 9 week of BM program. Carbohydrate, protein and fat intakes were significantly decreased at the end of the LCD but carbohydrate was the only macro nutrient that showed significant decrease (p < 0.05) at the end of the BM program compared to baseline. Calcium and iron intakes decreased significantly (p < 0.01, respectively) with no significant changes in other micronutrients at the end of the LCD. The mean weight of the subjects decreased from 73.8 $\pm$ 8.0 kg to 69.2 $\pm$ 7.7 kg with LCD and ended up with 67.7 $\pm$ 7.1 kg after 9 weeks of BM. The 3 weeks of LCD reduced most of the anthropometric indices such as BMI, PIBW, fat weight, wast-to-hip ratio and subscapular and suprailiac skinfold thickness. The 9 weeks of behavior modification showed slight change or maintenance of each anthropometric measurements. Weight loss and decreased WHR with the diet program induced significantly decreased systolic blood pressure. SGOT, SGPT and serum insulin levels with improved serum lipid profiles. Biochemical parameters related to iron status such as hemoglobin, hematocrit were significantly decreased (p < 0.01) at the end of the LCD. But their mean values were within normal range. The mean serum 25 (OH) vitamin $D_3$ level significantly increased after whole diet program. Serum folate level significantly decreased after 12 weeks of diet program. In conclusion 3 weeks of LCD brought 4.6 kg reduction in body weight without risk of iron, zinc or vitamin D deficiency and 9 weeks of the BM was effective to maintain nutritional status with slightly more weight reduction (1.5 kg). However calcium intake and serum folate should be monitored during the LCD and BM because of increased risk of deficiencies.

Study on Energy and Nutrient Intake and Food Preference of the Elderly in Care Facilities (요양시설 거주 노인의 에너지와 영양소 섭취 실태 및 식품선호도 조사)

  • Kwon, Jong-Sook;Lee, Seung Hee;Lee, Kang Min;Lee, Yoonna
    • Korean Journal of Community Nutrition
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    • v.21 no.2
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    • pp.200-217
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    • 2016
  • Objectives: The purpose of this study was to assess energy and nutritional intake and investigate the preference for food and cooking methods of the residents in elderly care facilities. Methods: Data were collected from 72 residents (10 males and 62 females) aged ${\geq}70$ years in elderly care facilities using questionnaires, food photographs for estimating dietary intake and records for daily physical activity. Results: Average age of the study participants was 85.0 years and 41, 36 and 8 had dementia, hypertension and diabetes mellitus, respectively. 15%, 65% and 19% of subjects were physically mobile, enervated, and immobile, respectively. Daily energy intake was 1360.2 kcal in men and 1378.0 kcal in women, which were 68.0% and 86.1% of the estimated energy requirement (EER) of dietary reference intake for Koreans (KDRI) for ${\geq}75$ year old individuals, respectively. Estimated energy expenditure (EEE) of subjects calculated using formula from KDRI was 1361.9 kcal and EER calculated using estimated daily physical activity (EDPA) was 1232.9 kcal. Energy intake and EEE from KDRI were higher than EER from EDPA. Dietary intake of dietary fiber, calcium, potassium, zinc, vitamin $B_2$, niacin, vitamin C were lower, and protein, phosphorous, iron, sodium, vitamin A, vitamin $B_1$, vitamin $B_6$, vitamin E were higher than the corresponding ones of KDRI. Subjects liked meats, fishes and shellfish, and fruits, while subjects disliked milk, seaweeds and salted fish and salted vegetables. Cooked rice, soybean paste soup, beef, cooked sliced radish strip, and yogurt were favorite foods, with steam being a favorite cooking method. Subjects considered nutrition as the most important factor for improving food service quality. Conclusions: Results of this study could be utilized for improving food-service for the residents in elderly care facilities, and provide a basis for setting reference intake of energy and nutrients of the elderly having very low activity levels.