• 제목/요약/키워드: Mass fraction

검색결과 1,063건 처리시간 0.025초

대기 부유분진의 입경별 특성에 관한 연구 (Study on Characteristics by Aerodynamic Diameter of Airborne Suspended Particulate Matters)

  • 김성천;강달선;차영희
    • 한국환경보건학회지
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    • 제26권2호
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    • pp.108-115
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    • 2000
  • The mass fraction of PM10 had a bimodal distribution in the middle of between 2.1 ${\mu}{\textrm}{m}$, and the average mass fraction of particles less than 2.1~3.1 ${\mu}{\textrm}{m}$ was 54.1% for Pb and 890.8 ng/㎥ for Fe, respectively. For the concentration of PM10 and metallic elements by seasonal variation, PM10 showed bimodal distribution, while metallic elements showed different distributions by their sources. The ratios of fine particles to total mass were 0.45 for PM10, 0.41 for Cr, and 0.20 for Fe, 0.57 for Zn, 0.68 for Cd and 0.63 for Pb, respectively. That facts indicated that PM10, Zn, Cd, Cr and Pb were from anthropogenic sources, and Fe was from natural source. The geometric means and geometric standard deviations by seasonal variations were 3.6 ${\mu}{\textrm}{m}$ , 2.31 ${\mu}{\textrm}{m}$ in winter, 3.0 ${\mu}{\textrm}{m}$ , 2.49 ${\mu}{\textrm}{m}$ in spring, 2.7 ${\mu}{\textrm}{m}$ , 2.03 ${\mu}{\textrm}{m}$ in summer respectively. And, total efficiency of cascade impactor by seasonal variations were 49.6% in winter, 45.9% in spring and 44.5% in summer.

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Gas-Chromatography/Mass Selective Detector를 사용하여 쥐의 뇨시료 중 benzidine 대사체의 확인 및 in vitro 독성 (Identification of Benzidine Metabolites in Rats by Gas Chromatography/Mass Selective Detector and its Toxicity in vitro)

  • 류재천;권오승
    • 약학회지
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    • 제44권5호
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    • pp.384-390
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    • 2000
  • Metabolism study of the dye, benzidine, was performed by gas chromatography-mass selective detector (GC/MSD) in the urine of rats orally administered 100 mg/kg benzidine. Urine samples were collected in metabolic cages for 0-24, 24-48, and 48-72 hrs. Ten ml of the urine was extracted with XAD-2 resin and the XAD-2 column was eluted with methanol. After evaporation, benzidine and its metabolites were extracted with diethyl ether (for non-conjugated fraction). For conjugated metabolites, $\beta$-glucu-ronidase was added to the aqueous layer that was incubated for 1 hr at 5$0^{\circ}C$ and the aqueous layer was extracted as in non-conjugated fraction. Aliquot of trimethylsilylated derivatives was applied to the GC/MSD. The mutagenicity of benzidine and its acetylated metabolites was tested by histidine/reversion assay. Five metabolites observed and confirmed either by electron impact and chemical ionization modes of the GC/MSD, or authentic compounds were monoacetyl-, diacetyl-, hydroxyacetyl-, hydroxydiacetyl-, and hydroxy-benzidine. Monoacetyl-benzidine was more potent than benzidine in histidine/reversion assay. This data indicates that monoacetylation of benzidine may be one of the metabolites produced in metabolic activation process.

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HFC-404a와 Polyol ester 오일 혼합물의 증기압 측정 (Measurement of Vapor Pressure of HFC-404a and Polyol ester Mixture System)

  • 박영무;김락현
    • 에너지공학
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    • 제18권3호
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    • pp.203-211
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    • 2009
  • 기존의 CFC 계열 및 HCFC 계열 냉매들이 오존층 붕괴와 지구온난화의 원인들 중의 한가지로 밝혀지면서 이것을 대체할 수 있는 냉매의 개발은 주요한 연구과제였다. 이제 몇 가지 대체 냉매들이 개발되면서 이것들 이 냉동시스템에 사용될 때 발생하는 상용성 (Compatibility)이 연구될 필요가 있다. 본 연구에서는 대체냉매의 상용성 연구의 일환으로 1,1,1,2-Tetrafluoroethane(HFC-134a) +1,1,1-Trifluoroetane(HFC-143a) + Pentafluoroethane (HFC-125)의 혼합대체냉매 HFC-404a 와 냉매 윤활유의 하나인 POE 오일 혼합물의 증기압을 측정하였다. 측정온도범위는 냉매 시스템의 운전온도를 고려하여, 263.15K 에서 323.15 K로 하였으며 오일농도범위는 0 mass% 에서 90 mass% 까지로 하였다. 측정결과 273.15K 이하의 온도에서 오일 농도 30 mass%까지 증기압에 대한 오일의 영향은 미미하였으며 50 mass% 이상에서는 증기압이 급격히 떨어지는 것이 밝혀졌다. 측정자료를 이용하여 HFC-404a와 POE 오일 혼합물의 증기압을 예측할 수 있는 모형을 개발 하기 위하여 Rault 모델과 Flory-Huggins 모델을 사용하여 측정치와 비교하였다. 그리고 보다 정확하고 실용적으로 증기압을 예측할 수 있는 경험식을 도출하였다.

Preprocessing and mass evolution of dark halos in the hydrodynamic zoom-in simulation

  • 한산;;최호승;;;;이석영
    • 천문학회보
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    • 제43권2호
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    • pp.38.2-38.2
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    • 2018
  • To understand the assembly of the galaxy population in clusters today, it is important to first understand preprocessing, the impact of environments prior to cluster infall. We use 15 cluster samples from YZiCS, a hydrodynamic cluster zoom-in simulation to determine the significance of preprocessing, and focus on the tidal mass loss of dark matter halos. We find ~48% of the cluster member halos were once satellites of another host. The preprocessed fraction depends on each cluster's recent mass growth history. Also, we find that the total mass loss is a clear function of the time spent in a host. However, two factors can increase the mass loss rate considerably. First, if the satellite mass is approaching the mass of its host. Second, when the halo suffers tidal mass loss at a higher redshift. Being in hosts before cluster infall enables halos to experience tidal mass loss for an extended period of time.

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Antitumor Effect of Mugwort (Artemisia princeps Pampan.) in vivo

  • Hwang, Yoon-Kyung;Kim, Dong-Chung;Hwang, Woo-Ik
    • Natural Product Sciences
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    • 제5권1호
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    • pp.1-6
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    • 1999
  • This study was devised to observe the antitumor activity of mugwort (Artemisia princeps Pampan.) against ICR mice inoculated with sarcoma-180 cells. The antitumor compounds were partially purified from petroleum ether extract of mugwort by silicic acid column chromatography. The active fraction used in in vivo test was obtained under the elution with acetone in silicic acid column chromatography. When the acetone fraction was intraperitoneally injected to the mice which had been subcutaneously inoculated on the left groin with sarcoma-180, the growth rate of tumor (sarcoma-180 mass) was inhibited by 30%. In case the acetone fraction was injected to the mice which had been inoculated intraperitoneally with sarcoma-180, the average life span was prolonged by 20%. After the injection of the active fraction, the spleen index and ${\gamma}-globulin$ ratio (%) were increased significantly (p<0.05). The administration of acetone fraction did not cause any abnormality in the body and the homeostasis of mice. Those observations suggest that the acetone fraction of mugwort extract has an antitumor effect in vivo.

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A FULLY EMPIRICAL APPROACH TO GALAXY EVOLUTION

  • Renzini, Alvio
    • 천문학논총
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    • 제25권3호
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    • pp.65-69
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    • 2010
  • Observations of large samples of galaxies from low to high redshifts are composing a picture of remarkable simplicity: (1) The star formation rate (SFR) of starforming galaxies scales almost linearly with mass, strongly decline with cosmic time, and exhibits very small scatter around the average relation. (2) Due to the high observed SFRs the mass of galaxies at high redshifts must increase very rapidly, and yet the mass function of star forming galaxies evolves only very slightly with redshift. (3) At all redshifts the fraction of quenched (passively evolving) galaxies increases with galactic stellar mass and with local overdensity, with the remarkable property that the relative efficiency of "mass quenching" is independent of environment, and that of "environment quenching" is independent of mass. In a recent paper by the zCOSMOS collaboration, Peng et al. (2010) demonstrate that these three empirical facts suffice to account for the observed evolution of the galaxy mass function and naturally generate the "double-Schechter" mass function for quenched galaxies.

LC/MS를 이용한 카바메이트계 잔류농약 확인방법 (Confirmation of carbamate pesticides by liquid chromatography coupled with electrospray ionization mass spectrometry)

  • 박준조;금모래;고광춘;박병옥;이성식
    • 한국동물위생학회지
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    • 제25권1호
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    • pp.23-29
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    • 2002
  • A method was developed to separate, detect and qualify aldicarb, bendiocarb, carbaryl, carbofuran, ethiofencarb, methomyl, methiocarb, propoxur in meats and fruits. Experimental beef and fork samples were fortified with 0.05mg/kg of carbamate pesticides for analysis. Carbamate-detected pear by HPLC fluorescence detector(HPLC/FLS) are extracted with acetonitril and refined by solid phase extraction(SPE) filled with aminopropyl-bonded silca, In the following step, the injected materials into LC/MS are analyzed to result in the fact that bendiocarb, carbaryl, carbofuran, ethiofencarb, methomyl, methiocarb, propoxur presents several sorts of fraction ions following with; [M+H]$^{+}$, [M+Na]$^{+}$,[M-CONH$CH_3$]$^{+}$, [M-OCONH$CH_3$]$^{+}$. In addition, ethiofencarb presents [M-SCH$_2$$CH_3$]$^{+}$ ion distinctive and aldicarb presents [M+Na]$^{+}$ and [M-OCONH$CH_3$]$^{+}$ ion which is the most decisive fraction ion for pesticides such as bendiocarb, carbaryl, carbofuran, ethiofencarb, methiocarb, methomyl, propoxur excluding [M+H]$^{+}$ ion. However, [M-OCONH$CH_3$]$^{+}$ and [M-OCONH$CH_3$]$^{+}$ fraction ion charactering carbamate pesticides are detected most efficiently with fragment voltage 50ev. As a result, for rluantitative analysis, [M+Na]$^{+}$ ion is the most decisive ion for detection of aldicarb and [M+H]$^{+}$ ion is the most decisive fraction ion for Pesticides such as bendiocarb, carbaryl, carbofuran, ethiofencarb, methiocarb, methomyl, propoxur. Carbaryl-detected pear by HPLC/FLS are analyzed by L/MS and the result shows that [M+H]$^{+}$ and [M-CONH$CH_3$]$^{+}$ ions charactering carbaryl are detected.ering carbaryl are detected.

Improved Injection Behavior with the Addition of Granulated β-Tricalcium Phosphate in Brushite Bone Cement

  • Jo, Hyun-Ho;Oh, Kyung-Sik
    • 한국세라믹학회지
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    • 제55권6호
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    • pp.590-596
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    • 2018
  • To improve the injection behavior of brushite cement, dense ${\beta}-Ca_3(PO_4)_2$ (${\beta}-TCP$) granules were added to the starting material. The spherical ${\beta}-TCP$ granules prepared by spray-drying and subsequent sintering at $1000{\sim}1200^{\circ}C$ accounted for fractions of from 0.5 to 0.7 of the total ${\beta}-TCP$. The injection behavior was evaluated by measuring the injected mass divided by the loaded mass of paste in the syringe pump. The injected amount was increased with the increase in the fraction and sintering temperature of ${\beta}-TCP$ granules, except at $1200^{\circ}C$. The increase in the fraction of ${\beta}-TCP$ and its sintering temperature resulted in a decrease in the plastic limit, which is the volume of water required to liquefy the compact. The rest water could be utilized in the cement with the reduced plastic limit for improved injectability. The amounts of rest water assigned for powdery phase were estimated, and correlated with the injectability of paste.

In Vitro and in Vivo Metabolism of Salsolinol, on Endogenous Isoquinoline Neurotoxin, in Rats

  • Rhee, Hee-Kyung;Kwon, Oh-Seung;Ryu, Jae-Chun
    • 한국환경성돌연변이발암원학회지
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    • 제21권1호
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    • pp.30-33
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    • 2001
  • Salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, SAL), a dopaminergic isoquinoline neurotoxin, has been implicated to contribute the etiology of Parkinson's disease and neuropathology of chronic alcoholism. In our previous results, SAL was reported to have the mutagenicity and clastogenicity not in bacteria but in mammalian cells, and its genotoxic potential was known to be potentiated in the presence of rat liver S-9 fraction. This may indicate that some metabolite(s) of SAL was involved in the mutagenic potentials. To investigate the SAL metabolites, the metabolism studies of SAL were conducted in vitro rat liver S-9 fraction and in vivo using rats by high performance liquid chromatography and gas chromatography/mass spectrometry. The methylated metabolite of SAL was found in urine of rats, while the same methylating form of metabolite was not produced from the in vitro metabolism system using rat liver S-9 fraction.

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원자로 가상사고시(노심) 용융물 고압 분출 모의 실험 연구 (Simulated Experiments on High Pressure Melt Ejection in the Reactor Cavity During Severe Accident)

  • 정한원;김도형;이규정;김상백;박래준;김희동
    • 대한기계학회논문집B
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    • 제24권11호
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    • pp.1447-1456
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    • 2000
  • Simulated experiments of high pressure melt ejection(HPME) are performed to measure the released fraction of corium simulant from the French type PWR cavity. The experiments are carried out on a 1/20th linear scaled model of the Ulchin 1&2 cavity. Water or woods metal and nitrogen is used as simulant of molten corium and steam, respectively. Experimental parameters are water mass, annulus area and breach size. It is shown that only breach size effects is very important while the mass and the annulus area do not affect the released fraction. It is found that the liquid film transport is much more dominant mechanism than the entrainment droplet transport, especially in linear scale down simulated HPME experiment.