• Title/Summary/Keyword: Microwave plasma

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Formation of the Diamond Thin Film as the SOD Sturcture (SOD 구조 형성에 따른 다이아몬드 박막 형성)

  • Ko, Jeong-Dae;Lee, You-Seong;Kang, Min-Sung;Lee, Kwang-Man;Lee, Kae-Myoung;Kim, Duk-Soo;Choi, Chi-Kyu
    • Korean Journal of Materials Research
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    • v.8 no.11
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    • pp.1067-1073
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    • 1998
  • High quality diamond films of the silicon on diamond (SOD) structure are deposited using CO and $H_2$ gas mixture in microwave plasma chemical vapor deposition (CVD), a SOD structure is fabricated using low pressure CVD polysilicon on diamond/ Si(100) substrate. The crystalline structure of the diamond films which composed of { 111} and {100} planes. were changed from octahedral one to cubo-octahedron one as the CO/$H_2$ ratios are increased. The high quality diamond films without amorphous carbon and non-diamond elements were deposited at the CO/$H_2$ flow rate of 0.18. and the main phase of the diamond films shows (111) plane. The diamond/Si(lOO) structure shows that the interface is flat without voids. The measured dielectric constant. leakage current and breakdown field were $5.31\times10^{-9}A/cm^2$ and $9\times{10^7}{\Omega}cm$ respectively.

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Mineral Contents of Underground Vegetables Produced in Different Regions of Korea (국내산 식용 지하 부위 채소의 생산지역에 따른 무기질 성분 함량에 관한 연구)

  • 장경미;이미순
    • Korean journal of food and cookery science
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    • v.16 no.5
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    • pp.425-430
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    • 2000
  • This study was carried out to estimate mineral contents of some underground vegetables including potatoes, sweet-potatoes, carrots, radishes, onions, and garlics produced in Korea using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry). According to the measurements, the contents of Na, Mg, Al, K, Ca, Mn, Fe, Zn, and P in Korean underground vegetables were variable depending upon producing areas and individual plants. Compared with other underground vegetables, the contents of Na in carrots and lotus roots were quite high. The contents of Cd, Ag Co. and Sr appeared to be below hazard levels. It is expected that this study can be used to calculate the mineral intake from underground vegetables.

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Determination of Metallic Elements in Urban Particulate Matter (SRM 1648) by ICP-MS and AAS (ICP-MS와 AAS를 이용한 대기 입자상 표준물질 (SRM 1648) 금속성분의 정량에 관한 연구)

  • Yoo Su-Young;Choi Kum-Chan;Kim Ki-Hyun
    • Journal of Korean Society for Atmospheric Environment
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    • v.21 no.4
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    • pp.423-430
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    • 2005
  • This study was investigated with sample digestion techniques and a reliability of the analytical results for a quantitative analysis of a standard reference material ('urban particulate matter', SRM 1648). The metallic elements were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) with closed vessel microwave acid digestion method and atomic absorption spectroscopy (AAS). Quality control of the overall analytical procedures for metallic element determinations of standard reference material were estimated by analysis of a SRM 1648. Three digestion solutions $(type\;1:\;HNO_3,\;type\;2:\;HNO_3\;and\;H2O_2(4'1)\;mixture,\;type\;3:5.55\%\; HNO_3\;and\;16.75\%\;HCI\;mixture)$ were applied to SRM 1648. As a result, three digestion solutions used in this study are completely unable to digest Cr of SRM 1648. Reliability of Cr and As showed some errors in the digestion with digestion solution type (3) due to the influence of chlorides. Type (3) digestion solutions are sufficient to fulfill the digestion of As as well as Se in SRM 1648. ICP-MS results showed the improvement in accurate and precise determination of some trace elements like Cd, V and Pb in SRM 1648. It is important to use the proper digestion solution for each element to qualify analytical precision.

Radio and Hard X-ray Study of the 2011 August 09 Flare

  • Hwangbo, Jung-Eun;Bong, Su-Chan;Lee, Jeongwoo;Lee, Dae-Young;Park, Seong-Hong;Park, Young-Deuk
    • The Bulletin of The Korean Astronomical Society
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    • v.38 no.1
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    • pp.65.1-65.1
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    • 2013
  • The 2011 August 09 Flare is one of the largest X-ray flares of Sunspot Cycle 24 to attract a lot of attention for its various activities detected in coronal images. In this study we concern ourselves mostly on information of high energy electrons produced during this flare provided by hard X ray data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and radio data from the Korean Solar Radio Burst Locator (KSRBL) and Ondrejov. EUV images obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory are used to provide the context of magnetic reconnection. In our results, (1) HXR spectra have a rich spectral morphology. Initially it could be fit by one thermal component (T~30MK) and one single power law nonthermal spectrum, but later a better fit could be made by introducing an additional thermal component (T~55 MK). (2) Time delays between the KSRBL burst and the RHESSI hard X-ray emission were found which are more obvious at low frequencies and insignificant at high frequencies. (3) The HXR source lies in the core of the quadrupolar active region. In our interpretation based on AIA 94 A images, the outer part of the active region erupted to be blown out, leaving the intense hard X-ray emission concentrated in the core. We relate the appearance of the second thermal component to the evolution of the AIA 171 and 94 A images. The time delays of microwave peaks to HXR peaks are interpreted as indicating presence of trapped electrons in larger closed magnetic loops. With these result we conclude that the hard X ray and microwaves are due to impulsive acceleration in the low and high heights and a sigmoidal reconnection scenario.

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A Study on the Growth Rate and Surface Shape of Single Crystalline Diamond According to HFCVD Deposition Temperature (HFCVD 증착 온도 변화에 따른 단결정 다이아몬드 표면 형상 및 성장률 변화)

  • Gwon, J.U.;Kim, M.S.;Jang, T.H.;Bae, M.K.;Kim, S.W.;Kim, T.G.
    • Journal of the Korean Society for Heat Treatment
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    • v.34 no.5
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    • pp.239-244
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    • 2021
  • Following Silicon Carbide, single crystal diamond continues to attract attention as a next-generation semiconductor substrate material. In addition to excellent physical properties, large area and productivity are very important for semiconductor substrate materials. Research on the increase in area and productivity of single crystal diamonds has been carried out using various devices such as HPHT (High Pressure High Temperature) and MPECVD (Microwave Plasma Enhanced Chemical Vapor Deposition). We hit the limits of growth rate and internal defects. However, HFCVD (Hot Filament Chemical Vapor Deposition) can be replaced due to the previous problem. In this study, HFCVD confirmed the distance between the substrate and the filament, the accompanying growth rate, the surface shape, and the Raman shift of the substrate after vapor deposition according to the vapor deposition temperature change. As a result, it was confirmed that the difference in the growth rate of the single crystal substrate due to the change in the vapor deposition temperature was gained up to 5 times, and that as the vapor deposition temperature increased, a large amount of polycrystalline diamond tended to be generated on the surface.

Comparative Study of Hazardous Heavy Metal Contents by Cosmetic Type (화장품 유형별 유해 중금속 함량 비교 연구)

  • Lee, Jin hee;Kim, Ji Yeon;Park, Sang Gyu;Lee, Jae Ho;Yoon, Jong Ho;Kim, Gyoung Tae;Kim, Hae Jung
    • Journal of Environmental Health Sciences
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    • v.45 no.2
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    • pp.154-163
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    • 2019
  • Objectives: The hazardous heavy metal contents of cosmetics were investigated and the resulting values were compared by type of cosmetics: skin care preparations (SCP), hair preparations (HP), makeup preparations (MP), and eye makeup preparations (EMP). Methods: The hazardous heavy metal contents (Pb, As, Cd, Sb, Ni and Hg) were analyzed for 358 cosmetics products (187 SCP, 82 HP, 56 MP, and 33 EMP). Hg was measured by the amalgamation method, and other hazardous heavy metals were measured by inductively coupled plasma optical emission spectrometer (ICP-OES) after decomposition using the microwave method. Results: The mean contents of Pb, As, Cd, Sb, Ni, and Hg in cosmetics were 0.424, 0.068, 0.024, 0.398, $0.567{\mu}/g$, and Not Detected, respectively. All of the hazardous heavy metals were detected in most products, but below the recommended maximums of the Ministry of Food and Drug Safety. The level of Cd was the lowest at 14.8%, and Sb was the highest at 41.2%. Pb, Sb and Ni showed the highest mean value and detection rate in EMP. As, Cd, and Hg showed the highest in SCP, HP, and MP, respectively. Conclusion: Hazardous heavy metals were detected in most products. In particular, Pb, Sb, and Ni were broadly detected in EMP, meaning more stringent quality control is required.

Highly Sensitive sub-ppm level Trimethylamine Gas Sensor Based on Porous CuO/In2O3 Nanostructures (고감도 sub-ppm 수준의 다공성 CuO/In2O3나노구조 트리메틸아민 가스센서)

  • Sung Do Yun;Yoon Myung;Chan Woong Na
    • Journal of Sensor Science and Technology
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    • v.33 no.5
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    • pp.305-309
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    • 2024
  • Trimethylamine (TMA) is an organic amine gas that serves as a key indicator for evaluating the freshness of seafood. We synthesized a highly sensitive trimethylamine (TMA) sensor based on porous indium oxide (In2O3) nanoparticles (NPs) loaded with CuO in the range of 6.7 to 28.4 at.%. CuO was loaded by hydrazine reduction onto as prepared In2O3 NPs using the microwave irradiation method. Crystal structures, morphologies, and chemical composition of CuO/In2O3 nanostructures (NSs) were characterized by X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and inductively coupled plasma mass spectrometry. The response of the 23.8 at.% CuO/In2O3 to 2.5 ppm TMA at 325℃ was 5.7, which was 2.8 times higher than that of porous In2O3 NPs. The high sensitivity and selective detection of TMA were attributed to electronic interactions between CuO and In2O3 and the high catalytic activity of CuO to TMA. Altogether, this CuO/In2O3 sensor could be used in the future to detect low concentrations of TMA, thereby aiding in the storage and distribution of marine food resources.

Monitoring Heavy Metals in Meat and Meat Products (식육 및 그 가공품의 중금속 모니터링)

  • Hwang, Tae-Ik;Ahn, Tae-Hyun;Kim, Eun-Jung;Lee, Jung-Ah;Kang, Myoung-Hee;Jang, Young-Mi;Kim, Mee-Hye
    • Korean Journal of Food Science and Technology
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    • v.43 no.5
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    • pp.525-531
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    • 2011
  • This study was conducted to examine the contents of lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in meat and meat products in Korea. The contents of Pb, Cd, As, and Hg in 466 samples of beef, pork, chicken, duck, ham, and sausage were measured using inductively coupled plasma mass spectrometry or a mercury analyzer. Wet ashing and microwave method were compared, and the recovery and reproducibility of the microwave method were better than those of wet ashing for meat and meat products. The recovery of the microwave method was 98.1% for Pb, 104.6% for Cd, and 103.4% for As, respectively. The best result was obtained through digestion using an acid mixture ($HNO_3$/$H_2O_2$, 6:2). Hg content was measured using a mercury analyzer. As a result, the contents of Hg and Cd in samples were lower than those of Pb and As. The average contents of Pb were 0.009 mg/kg in beef, 0.010 mg/kg in pork, 0.006 mg/kg in chicken, 0.007 mg/kg in duck, 0.005 mg/kg in ham, and 0.009 mg/kg in sausage. The average Cd contents were 0.0004 mg/kg in beef, 0.0004 mg/kg in pork, 0.0005 mg/kg in chicken, 0.0012 mg/kg in duck, 0.0015 mg/kg in ham, and 0.0019 mg/kg in sausage. The average As contents were 0.016 mg/kg in beef, 0.004 mg/kg in pork, 0.021 mg/kg in chicken, 0.010 mg/kg in duck, 0.014 mg/kg in ham, and 0.018 mg/kg in sausage. The average Hg contents were 0.713 ${\mu}g/kg$ in beef, 0.902 ${\mu}g/kg$ in pork, 0.710 ${\mu}g/kg$ in chicken, 0.796 ${\mu}g/kg$ in duck, 1.141 ${\mu}g/kg$ in ham, and 1.052 ${\mu}g/kg$ in sausage. Based on the results of the National Health and Nutrition Survey 2005, the levels of dietary exposure to heavy metal contaminants in meat and meat products were compared with the provisional tolerable weekly intake(PTWI) established by the Joint FAO/WHO Expert Committee on Food Additives. The average dietary exposure of the general population from meat and meat products was 0.03-0.2% of PTWI for Pb, Cd, As, and Hg, which indicates a safe level for public health at present.

Monitoring of Heavy Metals in Fishes in Korea -As, Cd, Cu. Pb, Mn, Zn, Total Hg - (유통 중인 어류의 중금속 모니터링 - 비소, 카드뮴, 구리, 납, 망간, 아연, 총수은 -)

  • Kim, Hee-Yun;Kim, Seo-Young;Lee, Jin-Ha;Jang, Young-Mi;Lee, Myoung-Sook;Park, Jong-Seok;Lee, Kwang-Ho;Kim, Jin-Chul
    • Korean Journal of Food Science and Technology
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    • v.39 no.4
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    • pp.353-359
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    • 2007
  • This survey was carried out to estimate the heavy metal contents of fishes (531 ocean fishes and 80 freshwater fishes) sold in and around Korea from April to October in 2006 . The contents of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), manganese (Mn), zinc (Zn) and mercury (Hg) were estimated by inductively coupled plasma-mass spectrometry (ICP-MS) and a mercury analyzer. The concentrations [mean (minimum-maximum) mg/kg] of heavy metals in the ocean fishes were as follows: As=2.523 (0.140-65.543), Cd=0.017 (0.000-0.108), Cu=0.569 (0.040-5.634), Pb=0.023 (0.000-0.323), Hg=0.068 (0.002-0.754), Mn=0.395 (0.016-4.651) and Zn=6.086 (0.529-34.729). The concentrations of heavy metals in the freshwater fishes were: As=0.370 (0.024-2.231), Cd=0.01l (ND-0.086), Cu=0.628 (0.003-1.962), Pb=0.026 (ND-0.423), Hg=0.058 (0.006-0.349), Mn=1.150 (0.069-7.230) and Zn=9.980 (3.463-82.737). The weekly intakes of Cd, Hg and Pb from fish were 0.9, 1.6 and 0.9%, respectively, as compared with the Provisional Tolerable Weekly Intake (PTWl) established by Joint FAO/WHO Expert Committee for food safety evaluation.

The Content of Heavy Metals in Herbal Pills Used as General Processed Food and Risk Assessment of Heavy Metal Intakes (유통 환(丸)제품의 중금속 함량 및 위해성 평가)

  • Kim, Sung-Dan;Jung, Sun-Ok;Kim, Bog-Soon;Yun, Eun-Sun;Chang, Min-Su;Park, Young-Ae;Lee, Young-Chul;Chae, Young-Zoo;Kim, Min-Young
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.39 no.7
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    • pp.1038-1048
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    • 2010
  • The purpose of this study was to investigate some heavy metals (Pb, Cd, Cr, Cu, Hg) in 52 commercial herbal pills used as general processed food, to identify weekly heavy metal intakes from herbal pills and to evaluate their potential health risks. The samples were digested with a microwave and determinations of heavy metal residues were carried out by inductively coupled plasma mass spectrometry (ICP-MS) and mercury analyzer. The mean values of heavy metal contents for herbal pills used as general processed food were Pb 0.421 (0.032~1.630), Cd 0.157 (0.011~0.515), Cr 1.033 (0.112~9.933), Cu 6.923 (1.333~16.755), Hg 0.010 (0.001~0.088) mg/kg. Lead contents of herba and cadmium of algae, herba were high (ANOVA-test, p<0.05). Levels of cadmium concentrations exceeding WHO reference values (0.3 mg/kg) were observed in 10 samples (4 species). The significant correlation was observed between Pb and Cd (r=0.633, p<0.01). The weekly intakes of Pb, Cd, Cr, Cu, Hg from herbal pills were 1.112 (0.072~5.088), 1.614 (0.029~9.257), 3.000 (0.252~23.690), 0.182 (0.008~1.235), 0.220 (0.000~0.420)%, respectively, as compared with the Provisional Tolerable Weekly Intake (PTWI) established by Joint FAO/WHO Expert Committee for food safety evaluation. Our data suggest regulations limiting heavy metals in herbal pills used as general processed food.