• Title/Summary/Keyword: Pb addition

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Preparation of PMN-PT-BT Powder by Modified Mixed Oxide Method and Effect of Ag on Dielectric Properties (Modified Mixed Oxide 방법에 의한 PMN-PT-BT 분말 합성 및 그의 물성에 미치는 Ag의 영향)

  • Lim, Kyoung-Ran;Jeong, Soon-Yong;Kim, Chang-Sam
    • Journal of the Korean Ceramic Society
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    • v.39 no.2
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    • pp.159-163
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    • 2002
  • A single phase perovskite relaxor ferroelectric PMN-PT-BT was prepared by a single calcination and the modified mixed oxide process. It was accomplished by ball-milling PbO, $Nb_2O_5,\;Ti(OC_3H_7)_4,\;BaCO_3,\;and\;Mg(NO_3)_2$ instead of MgO, removing the solvent, and then followed by calcination at 900$^{\circ}C$ for 2h. The specimen sintered at 1100$^{\circ}C$/2h showed the sintered density of 7.83 g/$cm^3$, room temperature dielectric constant of 22000, and dielectric loss of 2.5%. Addition of 1.0 mole% (0.3 wt%) of Ag as $AgNO_3$ and followed by calcination at 550$^{\circ}C$/2h lowered the sintering temperature to 900$^{\circ}C$. It still showed the sintered density of 7.88 g/$cm^3$, room temperature dielectric constant of 20000 and dielectric loss of 2.4%.

Analysis of Heavy Metal Element and Microorganism by Manufacture of Particulate Matter Sampler for Science Project of Secondary School (중등학교에서 사용 가능한 미세먼지 포집 장치 제작을 통한 대기 중 중금속 및 미생물 분석)

  • Kwon, Woo-Jin;Kim, Young-Jae;Byeon, Jung-Ho
    • Journal of the Korean earth science society
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    • v.36 no.1
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    • pp.125-135
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    • 2015
  • The purpose of this study were to sample particulate matter and analyze its elements and microorganisms for secondary school science project. The particulate matter was sampled on the rooftop a four-store building at a university in Chungju province. A simplified capturing system was developed with the parts, motor-pump, innet, $1.0{\mu}m$ teflon filter, filter-holder, etc. Using the system, this study had sampled particulate matter during Dec., 2013-Jun., 2014. Then, this study analyzed the elements and microorganisms of the sampled particulate matter. Results have been shown that the particulate matter derived China urban area is mainly consisted of the artificial pollutant, such as Cu, Zn, Cd, Ni, Pb. In addition, this study has been shown that microorganisms, such as bacteria and fungi, are included in the particulate matter. Therefore, this study suggests a new systemic investigation and monitoring about the particulate matter, specially originated from China. Also, this study provides a sample for secondary school science experiment.

Quality Characteristics of the Vaporized Liquid of Water-boiled Pine Needle (솔잎 열수 증류액의 품질특성)

  • Lee, Hyo-Jin;Cui, Cheng-Bi;Choi, Hyung-Taek;Kim, Soo-Hyun;Ham, Young-An;Lee, Deuk-Sik;Ham, Seung-Shi
    • Food Science and Preservation
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    • v.12 no.2
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    • pp.107-111
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    • 2005
  • We investigated the quality of vaporized liquid of water-boiled pine needle in the aspects of drinking conformity and aroma characteristics. As a result, there was no hazardous component in the assessment for 45 types of ingredients. Especially, inorganic components such as arsenic (As), lead (Pb), mercury (Hg), and cadmium (Cd) which are harmful to human body were not detected. Additionally, we observed that other ingredients were present within the standard level suitable for drinking. The total 34 volatile components of the vaporized liquid of water-boiled pine needle were identified by dynamic head-space method. Fenchol, bomeol $\beta-fenchyl$ alcohol and bomyl acetate were the major volatiles and composed of 6.7, 13.1, 26.6 and $16.2\%$ of total volatiles, respectively. In addition, the alcohols and aldehydes were the prominent ingredients of which the contents showed comparatively high.

Contamination Assessment of Heavy Metals in River Sediments (For the Surface Sediments from Nakdong River) (하천 퇴적물 내 중금속 오염도 평가에 관한 연구 (낙동강 수계 표층 퇴적물을 대상으로))

  • Kim, Shin;Ahn, Jungmin;Jung, Kangyoung;Lee, Kwonchul;Kwon, Heongak;Shin, Dongseok;Yang, Deukseok
    • Journal of Korean Society on Water Environment
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    • v.33 no.4
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    • pp.460-473
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    • 2017
  • In order to certificate the contamination assessment of heavy metals in surface sediments from the Nakdong river. Surface sediments were collected of 24 sampling sites (main 14st., tributary 10st.) and analyzed for grain size heavy metals contents. Study area mainly composed of sand (avg. 94.1%) and mean grain size was $1.46{\Phi}$ on average. Heavy metals contents (avg. Al: 12.5%, Zn; 74.4, Cr: 45.3, Li: 26.0, Pb: 17.1, Ni: 10.5, Cu: 7.8, Cd: 0.22 mg/kg) were relatively high contents in the composed of fine sediments. In addition, the results of pearson's correlation coefficient showed that most heavy metals and grain size (silt and clay) were highly correlated. The contents of Zn (6st.) and Ni (1st.) evaluated as moderately polluted, Zn (6st.) evaluated as LEL when compared with sediment quality standard of USEPA and Ontario sediment quality guidelines. Most heavy metals contents were I levels that dose not affected the benthos when compared with sediment pollution evaluation standard of NIER. The results of EX, EF, Igeo and CF showed the contents of Zn, Pb and Cd exceed the background contents and distributing of anthropogenic pollution and evaluated as moderately polluted level. And Nm-08 were relatively high level of contamination in the study area. However as results of PLI (less than 1), all sampling sites were evaluated unpolluted level.

Assessment for the Comparability between Korean Ministry of Environment Standard and ISO Standard for the Determination of Heavy Metals in Soil (토양 중금속 함량 측정에 대한 토양오염공정시험기준과 국제표준간의 적합성 평가)

  • Shin, Gun-Hwan;Lee, Goon-Teak;Lee, Won-Seok;Kim, Ji-In;Kim, Bo-Kyong;Park, Hyun-Jeong
    • Journal of Soil and Groundwater Environment
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    • v.17 no.3
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    • pp.1-9
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    • 2012
  • According to the agreement on WTO/TBT, we are under the situation to adopt international standard (ISO standard) as a national standard if it exists. However, in case of environmental area, it is a domestic legal obligation to use Korean environmental standard method(KESM) for analyzing various contaminants. Therefore it is necessary to assess the comparability between KEM and ISO standard prior to apply ISO standard to soil conservation law in Korea. The main purpose of this study is to assess the comparability of both methods for analyzing heavy metals in soil. We looked over various aspects like pre-treatment, calibration curve range, detection wavelength, soil organic matter content and so on. Apparently, the procedure of both methods is almost same. However in details, both methods are different in stationary time before aqua-regia extraction using reflux system, calibration curve range for Cu, Pb, Ni and measuring wavelength for Pb. According to the results of comparison test, the results were significantly different when the different calibration range was used. In case that all the extracts independent of methods were reanalyzed with the same calibration range of each method, both methods showed statistically same results. Other conditions like different stationary time, measuring wavelength of AAS and soil organic matter content did not have any influence on the analytical result. Therefore, we suggest to extend the calibration curve range to 0~8 mg/L which is used in KS I ISO standard(Korean standard related with environment which is translation version of ISO standard without any technical change). In case of $Cr^{6+}$, the results showed no significant differences between two methods even though the pretreatment, instrumentation and other analysis conditions were different. In addition to UV/Visble spectrometry of KESM for soil contamination, we suggest to adopt ion chromatography of ISO 15192(US EPA method 7199) for analyzing $Cr^{6+}$ with the consideration of laboratory work efficiency.

Investigation of Unintentionally Hazardous Substance in Teas (식수대용차 재료의 비의도적 유해물질 오염도 조사연구)

  • Park, Hye min;Kim, Ae Gyeong;Yang, Yong shik;Choi, Su Yeon;Seo, Doo Ri;Cho, Bae Sik;Seo, Kye Won;Kim, Jinhee
    • Journal of Food Hygiene and Safety
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    • v.35 no.2
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    • pp.162-169
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    • 2020
  • This study was conducted to survey levels of heavy metals, benzopyrene and mycotoxins in teas purchased from online markets, supermarkets, and traditional markets in Gwangju, Korea. We examined the arsenic, cadmium and lead content in heavy metals. We also tested for benzo(a)pyrene, which is classified as a carcinogen. In addition, we tested for the mycotoxins aflatoxin (AFB1, AFB2, AFG1, AFG2), ochratoxin A (OTA), fumonisin (FUB1, FUB2), and zearalenone (ZON). According to our results, heavy metals were detected within the allowable range (below 5.0 mg/kg for lead) and all samples met with the standards for tea as presented in the Korean Food Code. The Benzo(a)pyrene showed a detection rate of 12.8% in 16 of 125 samples and mycotoxins showed 23.2% in 29 of 125 samples. However, safe levels regarding benzo(a)pyrene and mycotoxin in tea were not ascertainable since the standards are not set in the Korean Food Code.

Chemical and Microbiological Hazard Analysis of Floor-Settled Dust in Elementary School Classrooms in Korea (국내 일부 초등학교 바닥먼지 내 화학적 및 생물학적 유해인자의 분석)

  • Kim, Ji-Young;Jung, Se-Young;Kim, Su-Jung;Kim, Jin-Ah;Si, Ji-Yeon;Jo, Yeon-Woo;Zoh, Kyung-Duk;Ko, Gwang-Pyo
    • Journal of Environmental Health Sciences
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    • v.37 no.4
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    • pp.279-288
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    • 2011
  • Objectives: This study investigated the levels and components of floor-settled dust in two elementary schools located at different sites (one near the Shihwa industrial complex and the other in a rural area) in order to evaluate the amounts of trace metal elements (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) and microorganisms. Methods: Over twenty settled-dust samples were collected from the two elementary schools. Trace metal elements were extracted from the dust using hydrochloric acid and nitric acid, and the amounts were measured by ICP-OES. Microbiological analysis was performed by bacterial culturing using R2A medium and denaturing gradient gel electrophoresis (DGGE). Results: The results showed that the amounts of three metal elements (Cr, Pb, and Zn) were significantly different between the schools (${\alpha}$=0.05, p<0.04). In addition, microbial communities in each school were highly correlated with one another. Among the identified microorganisms, a number of potentially opportunistic microorganisms, including antibiotic-resistant bacteria such as Acinetobacter baumannii, were found. Conclusions: This study will provide preliminary data for assessing levels and types of chemical and microbiological agents in elementary schools and for further evaluating human health risks associated with the agents.

Chemical Composition of Rainwater in Chonju-city, Korea (전주시에서 채수된 강수의 화학적 조성)

  • 나춘기;정재일
    • Journal of Korean Society for Atmospheric Environment
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    • v.13 no.5
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    • pp.371-381
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    • 1997
  • Precipitation sampls were collected in Chonju-city during October 1994 to September 1995 and were analysed for major ions (N $a^{+}$, $K^{+}$, $Ca^{2+}$, $Mg^{2+}$, C $l^{[-10]}$ , NO/$_3$, S $O_4$$^{2-}$) and trace metals (Al, Cd, Ni, Pb, Sr, Zn) in addition to pH, in order to understand the chemical characteristics of acid rain and to estimate the origin of the determined ions. Most rain showed a neutral or alkaline character, and only 35% had a pH lower than 5.6. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ are identified as the primary contributors to precipitation acidity in this region. Neutralization of precipitation acidity occurs as a result of the dissolution of alkaline compounds containing $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ precipitation concentrations exhibit a seasonal pattern in which higher concentrations are observed during spring months and lower concentrations during summer months. However, the seasonal behavior of $H^{+}$ concentrations differs from this pattern, in that the highest concentrations occur during autumn months, owing to the different influence of neutralization processes. In all rain, S $O_4$$^{2-}$ concentration exceeded NO/$_3$$^{[-10]}$ concentration. The contribution of maritime sources to the total S $O_4$$^{2-}$ concentration was very low or negligible. For rain strongly affacted by yellow sand, $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$ ions show a sharp increase in concentration, reflecting the increased amount of dust and soil suspended in atmosphere. At the same time, S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ concentrations are at their highest levels while $H^{+}$ values are not comparably elevated, presumably beacause much of the acidity has been neutralized by alkaline substances. The seasonal variance of trace metal concentrations in rainwater is similar to that of major cations. The annual wet flux of acidic pollutants and trace metals wat calculated to be as follows: N $O_3$$^{[-10]}$ ; 2.32 g/$m^2$, S $O_4$$^{2-}$, 5.34 g/$m^2$, Al; 6.30 mg/$m^2$, Cd; 0.62 mg/$m^2$, Ni; 4.08 mg/$m^2$, Pb: 9.76 mg/$m^2$, Sr; 5.94 mg/$m^2$, Zn; 111 mg/$m^2$./$m^2$.

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Development of Qualitative Evaluation of Medical Radiation Protective Apron (의료 방사선 방호용 앞치마의 정성적 평가법 개발)

  • Lim, Hui-Gyeom;Kim, Sang-Hyun;Kim, Tae-Hyung;So, Woon Young;Lee, Tae Hui;Kim, Seung Chul;Kim, Jin-Tae
    • Journal of radiological science and technology
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    • v.40 no.3
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    • pp.453-460
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    • 2017
  • This study proposes effective quality control and maintenance method by developing a new qualitative evaluation method of apron for medical radiation protection. As an experimental material, one of 0.45 mm lead and 100 of 0.45 mm Pb aprons were used and irradiated under the conditions of a tube voltage of 75 kVp and a tube current of 12.5 mAs to obtain an image. and using the Image J program, PSNR values were compared and analyzed. The results showed that there were 40 aprons (less than 11dB), 55 aprons (less than 11dB, less than 30dB), and 5 aprons (30dB or more). In addition, the dose showed a normal distribution for the apron, and 5 aprons with PSNR less than 11dB and 30dB or more were selected and divided into 8 zones, and these groups were statistically significant.

Evaluation of High Absorption Photoconductor for Application to Auto Exposure Control Sensor by Screen Printing Method (자동노출제어장치 센서적용을 위한 스크린 프린팅 제작방식의 고흡수율 광도전체 특성평가)

  • Kim, Dae-Kuk;Kim, Kyo-Tae;Park, Jeong-Eun;Hong, Ju-Yeon;Kim, Jin-Seon;Oh, Kyung-Min;Nam, Sang-Hee
    • Journal of the Korean Society of Radiology
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    • v.9 no.2
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    • pp.67-72
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    • 2015
  • In diagnostic radiology, the use of automatic exposure control device is internationally recommended for diagnosis and optimization. However, if exposed to prolonged radiation is a complicated manufacturing process, there is a problem that occurs decrease of various performance overall brightness sensor, which is commercially available conventional. Therefore, in this study, absorption of X-ray is high, and I want to evaluate the AEC applicability of the sensor of the photoconductor-based production has an easy advantage. Experimental results confirms the possibility of fabrication of the sensor through an increase in the SNR, with the detection efficiency superior, accurate turn-off. In addition, it is confirmed that the experimental results of the transmittance and the latent image, Ghost effect by the light conductor does not appear, in the case of a photoconductor with the exception of the PbO, 80% - and it was confirmed good transmittance of 90%. Therefore, excellent mechanical stability and poor performance due to a change of the doping concentration than the existing products that have been put to practical use, the sensor easy photoconductor based, fabrication and can be applied as AEC sensor is expected.