• Title/Summary/Keyword: 침적법

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Activity and Characteristics of Cu-Mn Oxide Catalyst Prepared by the Deposition-Precipitation Method (침적침전법에 의해 제조된 Cu-Mn 촉매의 활성 및 특성)

  • Kim, Hye-Jin;Choi, Sung-Woo;Lee, Chang-Seop
    • Journal of Korean Society for Atmospheric Environment
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    • v.22 no.3
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    • pp.373-381
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    • 2006
  • The catalytic combustion of toluene was investigated on the Cu-Mn oxide catalysts prepared by the deposition-precipitation method. Experiment of toluene combustion was performed with a fixed bed flow reactor in the temperature range of $100{\sim}280^{\circ}C$. Among the catalysts, 1.29Cu/Mn showed the most activity at $260^{\circ}C$. The deposition-precipitation method may be showed the potential to enhance the activity of catalysts. The catalysts were characterized by BET, scanning electron microscopy (SEM), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. On the basis of catalyst characterization data, the results showed that the surface of catalysts by deposition-precipitation method had uniform distribution and smaller particle size, which enhanced the reduction capability of catalysts. The XRD results showed that $Cu_{1.5}Mn_{1.5}O_{4}$ spinel phase was made by deposition-precipitation method, and increased catalyst activity and redox characteristic. It was assumed that the reduction step of $Cu_{1.5}Mn_{1.5}O_{4}$ spinel phase progressed $Cu_{1.5}Mn_{1.5}O_{4}\;to\;CuMnO_{2},\;and\;Cu_{2}O\;to\;CuMn_{2}O_{4}\;and\;Cu$.

A study on the powder synthesis of the amorphous calcium carbonate precursor for phosphors by wet chemical method (습식법에 의한 형광체 제조용 비정질 탄산칼슘 전구체 분말의 합성에 관한 연구)

  • 최종건;김판채;이충효
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.10 no.4
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    • pp.302-308
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    • 2000
  • Stable amorphous calcium carbonate were synthesized from the serial work for the synthetic conditions such as concentration of solution, reaction temperature, aging time and pH of mother liquor. By using this as a precusor, calcite, aragonite and vaterite crystal particles were obtained in the water from adequate crystallization conditions. Furthermore, characterization for flourescence were performed by using crystals which were crystallized from the Sn dopped amorphous calcium carbonate. Calcite showed the most intensive emission and the center of emission wavelength was 464 nm with pure blue color. Calcite is expected to be used as phosphor for flourescent lamp because the maximum emission intensity was obtained from the excitation with 255 nm wavelength.

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Determination of Sr-90 in the Vetebrae of Reference Korean (표준 한국인 척추골내의 Sr-90 함량 측정에 관한 연구)

  • Yung Jin Kim;Gook Hyun Chung
    • Nuclear Engineering and Technology
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    • v.16 no.3
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    • pp.131-135
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    • 1984
  • The determination of Sr-90 in 93 Korean vertebrae was carried out using modified method of tri-n-butyl phosphate extraction. As a result, the average content of Sr-90 in Korean vertebrae was 2.29 pCi/g Ca in the female and 1.73 pCi/g Ca in the male and the average level of both sexes was 2.01 pCi/g Ca, which was slightly higher than those of other countries. On the other hand, the Sr-90 injected into intraperitonal cavity of rat was accumulated in bones mostly and distributed evenly to various types of hones. The rate of accumulation and removal was not dependent on the amount of Sr-90 injected and over one half Sr-90 injected was accumulated in bones within one day and then it was removed gradually after two days from the injection.

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The Study of Water Stability of MDF Cement Composite by Addition of Epoxy Resin and Manufacturing Process (Epoxy Resin 첨가 및 제조공정에 따른 MDF 시멘트 복합재료의 수분안정성 연구)

  • 노준석;김태진;박춘근;최상홀
    • Journal of the Korean Ceramic Society
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    • v.35 no.4
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    • pp.371-377
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    • 1998
  • The effect of epoxy resin on the water stability of HAC/PVA based MDF cement composite were stu-died through the three different forming methods calendering extruding and warm pressing. In prexing step the epoxy resin was added in 5-15wt% of cement weight. The 3-point flexural strength of each dry and wet specimen which were immersed in water during 3. 7, 14 days was estmated and the mi-crostructural change of epoxy resin-added MDF cement composite due to water immersion was charac-terized by scanning electron microscopy. As the addition amount of epoxy resin the im-provement of water stability of MDF cement composite was achieved in most case. Especially through the warm press forming method the effectiveness of epoxy resin addition to the water stability was enhanced. When the epoxy resin was added by 5wt% to 7wt% the optimum flexural strength and water stability

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The Effect of CTSA Treatment on the Corrosion Resistance of AA5052 Alloy (AA5052 합금의 내식성에 영향을 미치는 CTSA처리의 영향)

  • Gu, Ga-Yeong;Bae, Seong-Hwa;Son, In-Jun;Jeong, So-Yeong;Baek, Ji-Yeon;Im, Lee-Geun
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2018.06a
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    • pp.91-91
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    • 2018
  • 스마트폰 및 카메라 케이스 등에 널리 적용되고 있는 알루미늄은 내식성, 내마모성과 같은 물리적, 화학적 성질이 우수하지 못하여 이를 향상시키기 위해 양극산화법이 산업적으로 널리 이용되고 있다. 알루미늄에 양극산화법을 적용하면 강도, 내마모성 및 내식성이 향상될 뿐만 아니라 알루미늄 표면에 규칙적으로 배열된 30nm~100nm 크기의 pore에 염료를 흡착시켜 다양한 색상의 외관을 가지는 양극산화피막을 형성시킬 수 있다. Pore간의 간격은 수십 nm~수백 nm 정도이며, pore의 크기와 간격 및 깊이는 양극산화조건(양극산화 전압, 전해액의 종류와 농도 및 온도)에 의해 크게 변화한다. 본 연구에서는 CTSA를 통한 AA5052합금의 양극산화 착색처리와 내식성의 개선 여부를 조사하였다. 알루미늄은 Al5052에는 Mg 외에, 소량의 Si을 포함하고 있다. 이 Si는 알루미늄 표면에 석출물 형태로 존재한다. 이 Si 석출물은 양극산화 시 기지상의 알루미늄 표면의 pore 형성을 방해하는 원인이다. 이러한 Si 석출물의 존재가 균일한 pore 형성을 방해하게 되고, 불균일한 포어를 가지는 표면은 착색처리 시 색상의 편차를 크게하는 원인이 되어 불량률을 높인다. 이러한 요인을 개선하기 위해 CTSA의 처리조건을 최적화 하였다. Al5052 합금을 이용하여 에칭, 디스머트, CTSA처리를 실시하였다. $55^{\circ}C$ 100g/L NaOH 용액에서 에칭을, $25^{\circ}C$ 10 vol.% $HNO_3$ 용액에서 디스머트를 실시한 다음, CTSA의 조건을 다르게 하고 SEM을 통해 Si 석출물의 감소율을 비교하였다. CTSA조건으로는 시간(60s, 180s, 300s), 농도(10%, 20%, 30%, 40%) 및 온도($25^{\circ}C$, $40^{\circ}C$, $50^{\circ}C$, $60^{\circ}C$)를 변화시켰으며, CTSA 처리 전과 후의 시편의 위치를 동일하게 하여 비교하였다. 결과 적정 시간, 농도, 온도 조건하에 pore를 불균일하게 하는 Si 석출물들이 제거되는 것을 확인할 수 있었다. CTSA 처리는 온도가 높을수록, 시간이 길수록, 농도가 적당히 진할수록 석출물이 잘 제거되는 것을 확인하였다. 또한 CTSA처리가 알루미늄의 내식성에 미치는 영향을 확인하기 위해서 침적시험에 의한 무게감소율 및 전기화학측정을 실시하였다.

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Bioactivity behavior of biphasic calcium phosphate powders prepared by co-precipitation method (공침법으로 합성된 biphasic calcium phosphate 분말의 생체활성 거동)

  • Kim, Tae-Wan;Kim, Dong-Hyun;Jin, Hyeong-Ho;Lee, Heon-Soo;Park, Hong-Chae;Yoon, Seog-Young
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.22 no.2
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    • pp.99-104
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    • 2012
  • The co-precipitation technique has been applied to synthesize biphasic calcium phosphate (BCP). $Ca(NO_3)_2{\cdot}4H_2O$ and $(NH_4)_2HPO_4$ as the starting materials was used. X-ray diffraction (XRD) and Fourier transformed infrared (FT-IR) spectroscopy were used to characterize the structure of as-synthesized and calcined BCP powders. After immersion in Hanks' Balanced Salt Solution (HBSS), for 1 week a precipitation started to be formed with individual small granules on the specimen surface. An MTT assay indicated that BCP powders have no cytotoxic effects on MG-63 cells, and that they have good biocompatibility.

Examining the Interrelation of Total, Soluble, and Bioavailable Metals in the Sediments of Urban Artificial Lakes (도심인공호 퇴적물의 총중금속, 용존중금속, 생물이용성 중금속의 연관성 규명)

  • Baek, Yong-Wook;An, Youn-Joo
    • Korean Journal of Ecology and Environment
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    • v.41 no.1
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    • pp.66-72
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    • 2008
  • Total metals, soluble metals, and bioavailable metals were monitored at the sediments of urban lakes located in Seoul, Korea during spring season 2006. The metals measured were zinc, arsenic, chromium, copper, nickel, and cadmium, which are known to be toxic to human health and ecosystems. The main sources of heavy metals in the lakes were urban runoff and atmospheric deposition associated with air pollution in urban areas. Extraction by using a weak electrolyte solution (0.1 M $Ca(NO_3)_2$) was used to predict bioavailability of the metals. Among the six heavy metals studied, copper was the most bioavailable, based the weak electrolyte extraction techniques. Since metal toxicity is related to metal bioavailability, the results were consistent with the high ecotoxicity of copper, compared to other heavy metals. Overall results suggest that there was no direct relationship between total and bioavailable metal concentration, although zinc, copper and cadmium show some relationships.

Selective Catalytic Reduction (SCR) Technology Trend for the Removal of Nitrogen Oxide from Ship Flue Gas (선박 배가스 내 질소산화물 제거를 위한 선택적촉매환원법(SCR) 기술동향)

  • Won, Jong Min;Hong, Sung Chang
    • Prospectives of Industrial Chemistry
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    • v.22 no.5
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    • pp.25-40
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    • 2019
  • 전 세계적으로 환경문제를 해결하기 위한 방안으로 환경규제를 강화시키며 특히 다양한 대기오염 물질 중 최근 큰 이슈인 초미세먼지 저감을 위해 전구물질로 알려진 질소산화물을 제어하기 위한 다양한 기술개발이 가속화되고 있다. 특히, 다양한 처리기술 중에 기술적·경제적인 이점을 갖춘 선택적 촉매환원법(selective catalytic reduction, SCR) 기술을 통하여 질소산화물 제거를 위해 암모니아를 환원제로 반응에 참여시켜 인체에 무해한 H2O, N2로 전환하는 기술이 대표적이다. 최근 전 세계적으로 다양한 산업군에서 질소산화물이 배출되고 있으며, 점오염원뿐만이 아니라 비점오염원(mobile sources)에 대한 규제가 강화되고 있다. 디젤엔진이 장착된 선박 배가스 처리장치 내 SCR 기술이 주목을 받고 있으며, NH3-SCR에 사용되는 촉매는 주로 VOx/TiO2, VOx/W/TiO2 촉매가 대표적이다. 한편 선박 디젤엔진에 사용되는 연료에 따라 연소배가스 특성이 다르다. 이러한 연료가 연소됨에 따라 SO2, SO3가 발생되고 환원제인 NH3와 결합하여 황산암모늄염((NH4)2SO4), ABS (ammonium bisulfate, NH4HSO4)과 같은 염을 형성시켜 탈질촉매의 비활성화 문제가 발생된다. 이러한 비활성화 물질이 침적된 탈질촉매를 재활성화 시키기 위하여 열 산화를 통해 재생시키고 있다. 이처럼 선박용 SCR 촉매는 강화되는 배출규제 및 엔진기술의 발달로 저감되는 운전 온도에 대비하여 저온 활성 재생이 가능한 고활성, 고내구성 촉매기술 개발이 필요하다.

Solid Phase Extraction(SPE) of Curcuminoids from Turmeric by Optimization Analytical Condition (최적 분석조건에 의한 강황으로부터 Curcuminoids의 고체상추출(SPE))

  • Lee, Kwang Jin;Ma, Jin Yeul;Kim, Young Jun;Kim, Young Sik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.10
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    • pp.4927-4935
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    • 2012
  • Turmeric is a medicinal herb with various pharmacological activities. Curcumin, demethoxycurcumin(DMC) and bisdemethoxycurcumin(BDMC) were extracted from turmeric by dipping and ultrasonic wave method. And extraction efficiency was identified using solid phase extraction(SPE). The extracted sample were simultaneously separated and analyzed from three kinds of commercial $C_{18}$ reversed-phase high performance liquid chromatography using water and acetonitrile as mobile phase with isocratic elution mode. Flow rate 1.0mL/min, injection volume $10{\mu}L$ and column oven temperature $40^{\circ}C$ at 425nm wavelength has been conducted. From the experimental results, the optimum mobile phase composition of water/acetonitrile 50/50vol% using RS tech column. It is evident that the amount of curcuminoids extracted(extraction time 4h) by 100% MeOH was higher than any aqueous MeOH composition. Finally, in 100% water extraction, the amount(mAU${\times}$mim) of curcuminoids extracted by SPE was 14.3 and 24.5 times respectively higher than ultrasonic wave and dipping method. The shown results can be applied as sources for pharmaceuticals and functional material.

The Effects of Insoluble Polymers on Water Stability of Carbon Fiber Reinforced Polymer-MDF Cementitious Composites (불용성 폴리머가 탄소섬유 보강 Polymer-MDF 시멘트 복합재료의 기계적 특성에 미치는 영향)

  • 김태진;박춘근
    • Composites Research
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    • v.12 no.3
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    • pp.84-90
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    • 1999
  • High alumina cement(HAC) and polyvinyl alcohol(PVA) based macro-defect-free(MDF) cement composites were reinforced using short carbon fibers, 3mm in length, 1-4% in weight fraction and insoluble polymers such as polyurethane, epoxy, phenol resin, in order to increase mechanical properties and water stability. The specimens were manufactured by the low heat-press(warmpress) method. In addition, the interface and the cross-linking reaction of cement and polymers was also studied by the SEM and TEM. Flexural strength of HAC/PVA based MDF cementitious composites was proportionally decreased with increasing fiber contents due to the undensified structure around fibers. The flexural strength of insoluble polymer added specimen was decreased with increasing fiber contents, while water stability was dramatically improved. Epoxy resin added specimen showed the highest strength with increasing fiber contents, compared with other specimens. The water stability of fiber content 4% added specimen immersed in water presented about 95%, 87% at 3 and 7 days immersed in water, respectively. The interfacial adhesive strength of fiber-matrix was very much improved due to cross linking reaction of polymer and metal ions of cement. Tensile strength of insoluble polymers added composites as linearly increased with increasing the fiber contents. The epoxy resin added specimen also showed highest tensile strength. The 4% fiber added specimen presented 30~80% higher strength than controlled specimen.

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