• The Korean Journal of Ceramics
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• v.6 no.4
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• pp.385-389
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• 2000

Residual stresses in epitaxial films were measured by X-ray diffraction method. Lattice strains of the (hkl) planes measured along particular Ψ-angles were converted to the in-plane stress according to the equation of stress-strain tensor conversion. Residual tensile stresses were observed in epitaxial PbTiO$_3$ films deposited on (100) SrTiO$_3$ substrate. Tensile stresses approximately 0.9 GPa were measured in Pb-rich films, while it increased to approximately 2.0 GPa with the decreasing of Pb content in the case of Pb-poor films, which ascribed to the formation of lead and oxygen vacancies (expressed as x in Pb$_1-x$TiO$_3-x$).

• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.12-15
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• 1986

Lead tolerance of $Pt/Al_2O_3$ catalysts was evaluated for CO oxidation depending on the properties of the alumina supports and base metals added as promoter. Among the four different alumina supports, the support with a large macropore volume (0.45 cc/g) and 5% Ce has shown the best resistence to lead poisoning. Most of the base metals added to the Pt-catalysts were found to be ineffective for improving lead resistence, but boron has shown an excellent lead tolerence, although it decreases the initial catalytic activity.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.378-381
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• 2015

To produce low cost and efficient photovoltaic cells, inorganic-organic lead halide perovskite materials appear promising for most suitable solar cells owing to their high power conversion efficiency. Most recent research showes that formamidinium lead iodide ($FAPbI_3$) with methylammonium lead bromide ($MAPbBr_3$) improves the power conversion efficiency of the solar cell to more than 18 per cent under a standard illumination because incorporated $MAPbBr_3$ makes $FAPbI_3$-relatively unstable but comparatively narrow band gap-more stable composition. In respect to first principle study, we investigated band gap of $MAPbI_3$, $FAPbI_3$, $MAPbBr_3$, $(FAPbI_3)_{0.89}-(MAPbBr_3)_{0.11}$ and 0.615(eV), 0.466, 1.197, 0.518 respectively through EDISON DFT software. These results emphasize enhancing structure stability is important factor as well as finding narrow band gap.

• Restorative Dentistry and Endodontics
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• v.12 no.2
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• pp.91-98
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• 1987

This study was designed to investigate the changing depositional pattern of inorganic enamel substances during enamel formation and maturation. For this purpose, white rat incisors which continuously grow and develop during the life, were chosen as specimens. And after treated with 20% KOH solution, outer surface of forming inorganic enamel were observed with the scanning electron microscope, dividing into 6 types according to the forming pattern from apical to cuspal direction. The observations lead to the following conclusions: 1. During the initial enamel forming stage, inorganic enamel substances were deposited with very irregular pyramidal shape on the root dentin surface. 2. During the enamel forming stage, inorganic enamel substances were deposited with relatively regular hexagonal, honey-comb appearance. 3. During the later enamel forming stage, inorganic enamel substances were deposited with very irregular and roughly amorphous appearance. 4. During the later enamel maturating stage, very small and round inorganic enamel substances were deposited densely, and made a flat enamel surface.

• 대한예방의학회:학술대회논문집
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• 1994.02a
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• pp.603-619
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• 1994

• Korean Journal of Materials Research
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• v.7 no.6
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• pp.522-528
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• 1997

RF-magnetron Sputtering Process를 이용하여 Pt/Ti/Si(100)기판위에 lanthanum-modified lead titanate 박막을 제작하였다. 기판온도와 증착시간이 증가함에 따라 증착율은 감소하였다. 기판온도가 증가함에 따라 fine grain들은 large grain으로 변화하였다. Perovskite구조는 기판온도 54$0^{\circ}C$, gas pressure 30mtorr에서 나타나기 시작하였다. 본 실험에서 perovskite 박막제작에 대한 조건은 기판온도 58$0^{\circ}C$, gas pressure 30mtorr였다. Pt/Ti/Si(100) 우선 배향된 박막을 얻었다. La양이 증가함에 따라 유전율, 항전계, 잔류분극량은 증가하였다. 중심주파수가 44.7MHz, 전파속도는 2680m/sec를 가지는 SAW filter 특성을 얻었다.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2003.10a
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• pp.161-161
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• 2003

• Journal of Korean Society of Environmental Engineers
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• v.39 no.4
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• pp.208-213
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• 2017

In this study, four inorganic pollutants (cadmium, chromium, manganese, lead), that could cause contamination events in drinking water distribution system, were selected and batch tests were carried out to determine the "minimum response concentration (MRC)", a part of Korean Contamination Warning system establishment. As the results, the minimum response concentration of cadmium was found to be 0.05 to 0.08 mg/L (0.005 mg/L : water quality standard) and that of chrome was 0.03 mg/L (0.05 mg/L). And the minimum reaction concentration was 0.005 mg/L for manganese (0.05 mg / L for water quality) and 0.02~0.08 mg/L for lead (0.01 mg/L).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.2
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• pp.196-208
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• 1998

To improve the quality of environmental measurements and evaluation of the workplace air in the pigment manufacturing industries, we analyzed metal(chromium, cadmium, lead, iron, cobalt, manganese, antimony, titanium, arsenic, and selenium) concentrations by ICP-AES in sixty seven samples of inorganic bulk pigments which are produced and/or used in Korea. We also collected MSDS which has to be supplied by manufacturer and/or supplier and posted in the workplace according to the Hazard Communication Standards, and compared the number of metals listed in each MSDS with the number of metals determined by ICP-AES. Results were as followed; 1. Among seventeen yellowish-colored samples, chromium(2~19%) and lead(0.1~61%) were the two major metals. In thirteen reddish-colored samples, iron was the major component with 37~81%. Cobalt and manganese were detected in blue-colored samples with less than 1%, while antimony and titanium were the major two metals in white-colored pigments with 178~300 ppm and with 36~65%, respectively. 2. In area samples collected in workplace air(one pigments producing factory and five retailer stores), iron and manganese were detected but the concentrations not exceeded the TLVs(1 and $5mg/m^3$, respectively). In three of fifteen samples, the concentrations of lead exceeded the TLV ($0.05mg/m^3$). 3. Two out of seven companies provided MSDS, and the average provision rate was 22.4%. And the coincidence rate of the number of metals referenced in MSDS and determined by ICP-AES mostly accorded, but in one sample, different metal was detected from MSDS. In summary, metals have to be concerned in evaluation of the workplace air dealing with compounds of inorganic pigments dust are cobalt, chromium, iron, manganese, lead and antimony, and these are simultaneously determined by ICP-AES. Taking this opportunity, it is needed to reinforce that the personnel is to be concerned about prevention of workers' ill health regarding to provision of MSDS.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.4.1-4.1
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• 2009

The dream of futurists andtechnologists is to build complex, multifunctional machines so small that theycan only be seen with the aid of a microscope. The unprecedented technologyadvancements in miniaturizing integrated circuits on semiconductors, and theresulting plethora of sophisticated, low cost electronic devices demonstratethe impact that micro/nano scale engineering can have when applied only to thearea of electrical and computer engineering. Emerging research efforts indeveloping organic and inorganic nano materials together with using micro/nanofabrication techniques for implementing integrated multifunctional devices hopeto yield similar revolutions in other engineering fields. By cross linking theindividual engineering fields through micro/nano technology, various organicand inorganic materials and miniaturized system devices can be developed thatwill have future impacts in the IT and life science applications. Yet to buildthe complex micromachines and nanomachine of the future, engineering will needto develop the technology capable of seamlessly integrating these materials andsubsystems together at the micro and nano scales. The micromachines of thefuture will be “integrated nanosystems,” complex devices requiring the integration of multiple materials,phenomena, technologies, and functions at the same platform. To develop thistechnology will require great efforts in materials science and engineering, infundamental and applied sciences. In this talk, we will first discuss thenature of micro and nanotechnology research for IT and life sciences, and thenintroduce selected current activities in micro and nanotechnology research fororganic and inorganic materials and devices. The newly developed micro/nanofabrication processes and devices, combined with in-depth scientificunderstandings of materials, can lead to rapid development of next generationsystems for applications in IT and life sciences.