• 제목/요약/키워드: chemical characteristic

검색결과 1,451건 처리시간 0.028초

GC/MS분석자료의 목표물질 인식에 관한 연구 (A Study on the Identification of Target Compounds From the GC/MS Data)

  • 민홍기;홍승홍
    • 대한의용생체공학회:의공학회지
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    • 제10권3호
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    • pp.223-228
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    • 1989
  • In this paper, the computerized interpretation of the analytical chemical data, especially GC/MS data, was performed for the purpose of prescreening of the target compounds. First, the data from the analytical instrument was analyzed to get the information about the retention time of the ISTD and the time inteval between the records. Second, the identification of the characteristic ion peaks was performed by calculating the ratio of the heights and the relative slope sensitivity of the characteristic mass abundance.

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액상세라믹의 원적외선 특성의 실험적평가 (Experimental Evaluation of Far Infrared Characteristic for Bio Liquid Ceramics used in Bulding finishing Materials)

  • 지철근;최태섭;장성일
    • 조명전기설비학회논문지
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    • 제16권6호
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    • pp.7-12
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    • 2002
  • 본 논문은 공동평가업체인 알파사에서 개발된 건축마감재인 바이오 액상세라믹의 물리, 화학적 특성 원적외 방사특성과 생체에의 효능을 실험을 통하여 평가한 것이다.

The Preparation of Alumina Particles Wrapped in Few-layer Graphene Sheets and Their Application to Dye-sensitized Solar Cells

  • Ahn, Kwang-Soon;Seo, Sang-Won;Park, Jeong-Hyun;Min, Bong-Ki;Jung, Woo-Sik
    • Bulletin of the Korean Chemical Society
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    • 제32권5호
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    • pp.1579-1582
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    • 2011
  • Alumina particles wrapped in few-layer graphene sheets were prepared by calcining aluminum nitride powders under a mixed gas flow of carbon monoxide and argon. The graphene sheets were characterized by powder X-ray diffraction (XRD), Raman spectroscopy, electron energy loss spectroscopy, and high-resolution transmission electron microscopy. The few-layer graphene sheets, which wrapped around the alumina particles, did not exhibit any diffraction peaks in the XRD patterns but did show three characteristic bands (D, G, and 2D bands) in the Raman spectra. The dye-sensitized solar cell (DSSC) with the alumina particles wrapped in few-layer graphene sheets exhibited significantly improved overall energy-conversion efficiency, compared to conventional DSSC, due to longer electron lifetime.

정수처리에서 전기응집과 화학응집의 처리효율 비교 (Comparison of Electrocoagulation and Chemical Coagulation in Removal on Water Treatment)

  • 한무영;송재민;박상철
    • 상하수도학회지
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    • 제18권5호
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    • pp.689-695
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    • 2004
  • Electrocoagulation has been suggested as a promising alternative to conventional coagulation. The process is characterized by reduced sludge production, no requirement for chemical use, and ease of operation. However, this coagulation has scarcely been studied in water purifying process. This study was performed several batch experiments to compare turbidity removal between electrocoagulation and chemical coagulation. In addition, characteristics of floe were evaluated with zeta potential and particle size distributions. Electrocoagulation showed a relatively higher removal of turbidity (approximately 5%) with the same aluminum amount than conventional chemical coagulation. In addition, turbidity removal by electrocoagulation was less sensitive to pH and was greater for more extensive pH range than chemical coagulation. The results of zeta potential and floc size distributions illustrated that electrocoagulation provided the preferable conditions for coagulation such as zeta potential close to zero millivolt and increased portions of particles in the range of 40 and $100{\mu}m$.

글리콜에테르계 혼화제가 콘크리트의 내구성 향상에 미치는 영향에 관한 연구 (A Study on Durability Improvement of Concrete Using Glycol Ether Chemical Admixture)

  • 김광기;송인명;정상진
    • 한국건축시공학회지
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    • 제7권4호
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    • pp.117-124
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    • 2007
  • Focused on the material-related aspect for enhancing the durability of concrete, the present study analyzed the effect of glycol ether admixture, which is a chemical admixture that can compact the structure of concrete by entraining air inside the concrete, on the basic physical properties and durability characteristic of the concrete. In analyzing the results of experiment, we examined the basic physical properties and durability characteristic of concrete according to addition rate based on OPC and selected the optimal addition rate. In addition, with the optimal addition rate, we added glycol ether admixture to concrete, which contained fly ash used as binder and high-performance water reducing agent for reducing the unit quantity, and examined changes in the characteristics of the concrete. According to the result, the optimal addition rate of glycol ether admixture was 3% of the unit quantity of cement, and the addition of binder and chemical admixture did not have a significant effect on unhardened concrete but reduced the air content. In addition, concrete showed resistance performance of around 30% to carbonation and around 40% to drying shrinkage. In addition, as for resistance to freezing and thawing, the relative dynamic modulus of elasticity was over around 85% through atmospheric curing. These performances prove the effect.

석탄연소 보일러에서 생성된 석탄회의 분석과 형성 메커니즘 해석에 대한 연구 (A Study on the Formation Mechanism of the Fly Ash from Coal Particles in the Coal Burning Boiler)

  • 이정언;이재근
    • 대한기계학회논문집B
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    • 제22권12호
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    • pp.1691-1701
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    • 1998
  • Fly ash produced in coal combustion is a fine-grained material consisting mostly of spherical, glassy, and porous particles. A study on the formation mechanism of the fly ash from coal particles in the pulverized coal power plant is investigated with a physical, morphological, and chemical characteristic analysis of fly ash collected from the Samchonpo power plant. This study may contribute to the data base of domestic fly ash, the improvement of combustion efficiency, fouling phenomena and ash collection in the electrostatic precipitator. The physical property of fly ash is determined using a particle counter for the measurement of ash size distribution. Morphological characteristic of fly ash is performed using a scanning electron micrograph. The chemical components of fly ash are determined using an inductively coupled plasma emission spectrometry(ICP). The distribution of fly ash size was bi-modal and ranged from 12 to $19{\mu}m$ in mass median diameter. Exposure conditions of flue gas temperature and duration within the combustion zone of the boiler played an important role on the morphological properties of the fly ash such as shape, particle size and chemical components. The evolution of ash formation during pulverized coal combustion has revealed three major mechanisms by large particle formation due to break-up process, gas to particle conversion and growth by coagulation and agglomeration.

화학적 인공 인접면 치아우식증의 디지털 영상 진단능 평가 (Diagnostic accuracy of digital images for detection of artificial chemical proximal caries)

  • 박금미;나경수
    • Imaging Science in Dentistry
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    • 제33권2호
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    • pp.91-95
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    • 2003
  • Purpose : To compare the diagnostic accuracy of proximal caries detection between Kodak Insight film and the Biomedisys CDX2000HQ digital (CCD) sensor. Materials and Methods: 156 proximal surfaces of extracted teeth, 78 of which had chemical artificial caries, were used in this study. Four observers interpreted the radiographs using a five-point confidence rating scale to record their diagnoses. The results were analyzed by receiver operating characteristic curves, ANOVA and Kappa values. Result: Analysis using receiver operating characteristic curves revealed the areas under each curve which indicated a diagnostic accuracy of 0.951 in Insight and 0.952 in CDX2000HQ digital sensor. ANOVA revealed no significant differences between the two images with respect to caries detection. Kappa values indicated that the mean intra-observer agreement was 0.85 and inter-observer agreement 0.71 in conventional radiography. In digital radiography, the mean intra-observer agreement was 0.84 and inter-observer agreement 0.72. Conclusion: The results suggest that no significant difference exists between the two modalities for artificial caries detection and that CDX2000HQ was as good as Insight film for this purpose.

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카퍼 프탈로시아닌의 완충효과 (Buffer Effect of Copper Phthalocyanine(CuPC))

  • 김정현;신동명;손병청
    • 한국응용과학기술학회지
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    • 제16권4호
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    • pp.307-311
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    • 1999
  • Interfacial properties of electrode and organic thin layer is one of the most important factor in performing a Light Emitting Diodes(LED). Phthalocyanine copper was used as a buffer layer to improve interface characteristic, so that device efficiency was improved. In this study, LEDs were fabricated as like structures of Indium-Tin-Oxide (ITO) / N,N' -Diphenyl-N,N'-di(m-tolyl)-benzidine (TPD) / 8-Hydroxyquinoline aluminum(Alq) / Aluminum(Al) and Indium-Tin-Oxide(ITO) / N,N'-Diphenyl-N,N' -di(m-tolyl)-benzidine(TPD) / 2-(4-Biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole(PBD) / Aluminum(Al). In these devices, CuPC was layered at electrode/organic layer interface. As position is changing and thickness is changing, devices showed characteristic luminescence efficiency and luminescence inensity respectively. We showed in this study that luminescence efficiency was improved with CuPC layer in LEDs. The efficiency of device with layer CuPC is higher than that of 2 layer CuPC. However, the luminescence of 2 layer CuPC device got higher value.

Characteristic Chemical Correlations in Nearby Star-forming Molecular Clouds

  • Yun, Hyeong-Sik;Lee, Jeong-Eun;Evans, Neal J. II;Offner, Stella;Heyer, Mark H.;Choi, Yunhee;Lee, Yong-Hee;Baek, Giseon;Choi, Minho;Kang, Hyunwoo;Tatematsu, Ken'ichi;Lee, Seokho;Yang, Yao-Lun;Gaches, Brandt;Chen, How-Huan
    • 천문학회보
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    • 제45권1호
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    • pp.41.1-41.1
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    • 2020
  • Different molecular lines trace different physical environments (with various densities and temperatures) within molecular clouds (MCs). Therefore, multimolecular line observations are crucial to study the physical and chemical structures of MCs. We observed the Orion A and Ophiuchus clouds in six different molecular lines as a Taeduk Radio Astronomy Observatory Key Science Program (TRAO-KSP), "mapping Turbulent properties In star-forming MolEcular clouds down to the Sonic scale" (TIMES; PI: Jeong-Eun Lee). Here, we investigate the characteristic relations between the observed lines by performing the Principal Component Analysis (PCA). We also investigate the correlation between the line intensity distributions and the physical parameters, such as the gas column density and dust temperature. Finally, we will discuss how the correlations among different chemical tracers vary with the star formation environments.

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