• Environmental Analysis Health and Toxicology
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• 제30권
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• pp.4.1-4.11
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• 2015

Objectives: This survey was designed to conduct the first nationwide dietary exposure assessment on hazardous substances including the intakes of functional food and herbal medicine. In this paper, we introduced the survey design and the results of the dietary exposure status and internal exposure levels of lead (Pb), cadmium (Cd), and mercury (Hg). Methods: We selected 4867 subjects of all ages throughout Korea. We conducted a food survey, dietary survey, biomonitoring, and health survey. Results: Pb and Cd were the highest (median value) in the seaweed ($94.2{\mu}g/kg$ for Pb; $594{\mu}g/kg$ for Cd), and Hg was the highest in the fish ($46.4{\mu}g/kg$). The dietary exposure level (median value) of Pb was $0.14{\mu}g/kg$ body weight (bw)/d, $0.18{\mu}g/kg$ bw/d for Cd, and $0.07{\mu}g/kg$ bw/d for Hg. Those with a blood Pb level of less than $5.00{\mu}g/dL$ (US Centers for Disease Control and Prevention, reference value for those 1 to 5 years of age) were 99.0% of all the subjects. Those with a blood Cd level with less than $0.30{\mu}g/L$ (German Federal Environmental Agency, reference value for non-smoking children) were 24.5%. For those with a blood Hg level with less than $5.00{\mu}g/L$ (human biomonitoring I, references value for children and adults, German Federal Environmental Agency) was 81.0 % of all the subjects. Conclusions: The main dietary exposure of heavy metals occurs through food consumed in a large quantity and high frequency. The blood Hg level and dietary exposure level of Hg were both higher than those in the European Union.

• Applied Microscopy
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• 제25권3호
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• pp.82-89
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• 1995

지금까지의 실험결과에서 다음과 같은 요약할 수 있다. 1) 사원계 $Zn_{1-x}Mg_{x}S_y$ $S_{1-y}$(x=0.13, y=0.16) 에피층은 다소 불규칙한 성장을 나타내어 역삼각형의 결함과 길고 직선인 적층결함으로 형성된 수지상 형태가 발견되었다. 2)역삼각형 결함은 {111}면에 형성된 적층결함으로 둘러싸여 있고 내부에는 결함이 없으나 계면과 수직인 방향인 <001>방향으로 콘트라스트 차이를 이루는 밴드가 형성되었다. 3) 기판과 정합을 이루고 있고 결함이 없는 ZnSe 버퍼 층이 관찰되었으며 결함 및 므와레 줄무늬는 버퍼층과 4원계 에피층과의 계면에서 형성된다. 4) 4원계 에피층에 형성된 적층결함은 Mg 원소의 효과로 길이가 60nm 이상 폭이 40nm 이상의 넓은 간격을 이루고 있다. 5) 긴 적층결함으로 둘러쌓인 수지상 구조에는 국부적으로 주기를 이루며 강한 콘트라스트 차이를 나타내는 줄무늬가 관찰되는데, 이는 Mg 및 S의 국부적인 화학적 조성차이에 기인한 탄성 변형 효과로 생각된다.

• 대한전자공학회논문지SD
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• 제45권11호
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• pp.1-7
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• 2008

본 연구에서는 양자 현상을 고려한 나노미터 MuGFET의 C-V 특성을 분석하기 위하여 2차원 Poisson-$Schr{\ddot{o}}dinger$ 방정식을 self-consisnt하게 풀 수 있는 시뮬레이터를 구현하였다. 소자 시뮬레이터를 이용하여 양자 현상으로 인한 소자크기와 게이트 구조에 따른 게이트-채널 커패시턴스 특성을 분석하였다. 소자의 크기가 감소할수록 단위 면적당 게이트-채널 커패시턴스는 증가하였다. 그리고 게이트 구조가 다른 소자에서는 게이트-채널 커패시턴스가 유효게이트 수가 증가할수록 감소하였다. 이런 결과를 실리콘 표면의 전자농도 분포와 인버전 커패시턴스로 설명하였다 또한 인버전 커패시턴스로부터 소자의 크기 및 게이트 구조에 따른 inversion-layer centroid 길이도 계산하였다.

• 약학회지
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• 제52권5호
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• pp.355-360
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• 2008

In this study we investigated antioxidant activity of against several free radicals and skin whitening effect of 70% ethanol extract (leaf extracts and branch/stem mixed) of Lindera obtusiloba BL. Antioxidant activity was assessed by DPPH, superoxide radical and hydroxyl radical assays. The Lindera obtusiloba BL. extract had antioxidant activity dose dependently with an ${IC}_{50}$ value of 243.14 and 181.10 ${\mu}g$/ml for DPPH, 165.77 and >1500 ${\mu}g$/ml for non-enzymatic system of superoxide radical assay, 35.47 and >100 ${\mu}g$/ml for enzymatic system of superoxide radical assay, 1.21 mg/ml for hydroxyl radical assay. In addition we tested tyrosinase inhibition activity and melanin contents on B16 melanoma F10. B16 melanoma cell was treated by such sample as 1, 5, 10 and 50 ${\mu}g$/ml for 72 hr and tyrosinase inhibition was tested. Melanogenesis was inhibited to 22% at the dose of 50 ${\mu}g$/ml and tyrosinase was inhibited to 45.2% at the same dose. In conclusion Lindera obtusiloba BL had potent antioxidant activity and inhibitory activity of tyrosinase and melanin formation. It could be developed as the health functional food and functional cosmetic resources.

• 한국산업보건학회지
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• 제6권1호
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• pp.88-96
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• 1996

This study was conducted to establish model between lead and ZPP concentration in blood of workers exposed to lead. Workers employed in secondary smelting manufacturing industry showed $85.1{\mu}g/dl$ of blood lead level, exceeding $60{\mu}g/dl$, the Criteria for Removal defined by Occupational Safety and Health Act of Korea. Average blood lead level of workers in the battery manufacturing industry was $51.3{\mu}g/dl$, locating between $40{\mu}g/dl$ and $60{\mu}g/dl$, the Criteria for Requiring Medical Removal. Blood lead level of in the litharge and radiator manufacturing industry was below $40{\mu}g/dl$, the Criteria Requiring Temporary Medical Removal. Blood lead levels of workers by industry were Significantly different(p<0.05). 50(21 %) showed blood lead levels above $60{\mu}g/dl$, the Criteria for Removal and 66(27.7 %) showed blood lead levels between the Criteria for Requiring Medical Removal, $40-60{\mu}g/dl$. Thus, approximately 50 percent of workers indicated blood lead levels above $40{\mu}g/dl$, the Criteria Requiring Temporary Medical Removal and should receive medical examination and consultation including biological monitoring. Average ZPP level of workers employed in the secondary smelting industry was $186.2{\mu}g/dl$, exceeding above $150{\mu}g/dl$, the Criteria for Removal. Seventy seven of all workers(32.3 %) showed ZPP level above $100-150{\mu}g/dl$, the Criteria for Requiring Medical Removal. The most appropriate model for predicting ZPP in blood was log-linear regression model. Log linear regression models between lead and ZPP concentrations in blood was Log ZPP(${\mu}g/dl$) = -0.2340 + 1.2270 Log Pb-B(${\mu}g/dl$)(standard error of estimate: 0,089, ${\gamma}^2=0.4456$, n=238, P=0.0001), Blood-in-lead explained 44.56 % of the variance in log(ZPP in blood).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1992년도 추계학술대회 논문집
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• pp.132-135
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• 1992

Diamond thin films by MWPECVD in methane-hydrogen mixed gas were studied, with emphasis on the investigation of the effect of discharge power and pressure. As a result, the growth rate of diamond thin films was affected by discharge power and the surface morphology of diamond thin films was affected by pressure. The growth rate of diamond films was about 1.65 ${\mu}m$/hr under the condition of MW power: 900W, pressure: 60torr, $H_2$ flow rate: 60sccm, $CH_4$ concentration: 1 % and deposition time: 5hr. The deposited diamond films were identified by SEM, XRD and Raman spectrophotometer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.342-344
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• 1995

Using piezoresistive effects of single-crystal and poly-crystalline silicon, pressure sensors of the same pattern were fabricated for comparison of temperature characteristics. Optimum size and aspect ratio of rectangular sensor diaphragm were calculated by FEM. For polsilicon pressure sensor, polysilicon resistors of Wheatstone bridge were deposited by LPCVD to be used in a wide' temperature range. Polysilicon pressure sensors showed more stable temperature characteristics than single-crysta1 silicon in the range of $-20\sim125[^{\circ}C]$. To get low TCO (Temperature Coefficient of Offset), below $\pm$3 [${\mu}V/V/^{\circ}C$], it is needed for each TCR of piezoresistors to have a deviation within $\pm25[ppm/^{\circ}C]$ less than $\pm500[ppm/^{\circ}C]$ of resistors for polysilicon pressure sensor can result in low TCS(Temperature Coefficient of Sensitivity) of -0.1[%FS/$^{\circ}C$].

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1226-1228
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• 1994

Applications of poly-Si layers which are important as sensing and structural material of various sensors were reviewed in this research. A piezoresistive pressure sensor with piezoresistors has sensitivity of $6.93{\mu}$ V/(VmmHg) within 300mmHg. Temperature sensor was studied with measurement range of $-40{\sim}140^{\circ}C$ and $400{\sim}800^{\circ}C$ using boron-doped and undoped poly-Si resistors, respectively. Poly-Si layer was used to transduce volume change of polyimide to stress of silicon diaphragm for humidity sensor.

• 전기학회논문지
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• 제58권9호
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• pp.1750-1756
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• 2009

In this paper, 5 kWh class Superconductor Flywheel Energy Storage System (SFES) was constructed including motor/generator, superconductor magnetic bearing(SMB), composite rotor and electromagnetic damper(EMD) system. High speed rotation test was performed after levitating flywheel rotor only using EMD without SMB. the PD controller of EMD was designed. the control system is constructed using xPC which is real time digital control system. the results of high speed rotation test showed that proposed EMD system have sufficient damping in cylindrical mode and conical mode, and vibration of wheel was suppressed below 10 ${\mu}m$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.432-435
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• 2002

The ultimate study of this research is to improve the properties of digital X-ray receptor based on amorphous selenium. There are being two prominent studying for Digital Radiography. Direct and Indirect method of Digital Radiography are announced for producing high quality digital image. But each two systems have strength and weakness. This is a basic research for developing of Hybrid digital radiography which is a new type X-ray detector. ln this study, we investigated the electrical characteristic of multi-layer$(CaWO_4+a-Se)$ as a photoconductor according to the changing iodine composition ratio. The iodine composition ratio of a-Se compound is classified into 5 different kinds which have 30ppm, 100ppm, 300ppm, 500ppm, 700ppm and were made test sample throught thermo-evaporation. The phosphor layer of $CaWO_4$ was overlapped on a-Se using EFIRON optical adhesives. We measured the dark and photo current about the test sample and compared the electrical characteristic of the net charge and signal-to-noise ratio. Among other things, test sample of compound material of 700ppm iodine showed good characteristic of $2.53nA/cm^2$ dark current and $479nC/cm^2{\cdot}mR$ net charge at $3V/{\mu}m$.