• Title, Summary, Keyword: mass size

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Size-mass relationships for 4 freshwater snails (Gastropoda: Pleuroceridae) from the Guem River in Korea

  • Yoon, Ho Seop;Choi, Sang Duk
    • The Korean Journal of Malacology
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    • v.29 no.1
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    • pp.83-85
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    • 2013
  • Size-mass relationships were estimated for 4 species belonging to genus Semisulcospira from the Guem River, Korea. These 4 freshwater snail species: Semisulcospira libertina, Semisulcospira coreana, Semisulcospira gottschei, and Semisulcospira forticosta. Between June and November 2011, samples were caught by dredge (mesh size 10mm of multifilament nylon, total length 4.35 m) at depths of < 2 m. Estimates of for parameter b of the size-mass relationship (W = $aSH^b$) ranged between 2.0072 (Semisulcospira libertina) and 2.3463 (Semisulcospira gottschei).

Initial Size Distribution of the Milky Way Globular Clusters

  • Shin, Ji-Hye;Kim, Sung-Soo S.
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.2
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    • pp.35.1-35.1
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    • 2010
  • Unlike the initial mass function, the initial size distribution of globular cluster (GC) systems is not well known. We calculate the evolution of the mass function (MF), radial distribution (RD), and size distribution (SD) of the Galactic GC system. By comparing the results from this calculation and the present-day MF, RD, and SD of the Galactic GC system, we infer the initial SD of the GC system. We find that a Gaussian distribution of the half-mass radius and a Gaussian distribution of the half-mass to Jacobi radius ratio are the best-fit initial SDs of the Galactic GC system.

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Characterization of submicron Particles Using a Single Particle Mass Spectrometer(I) - Non - Linear Correlation Between Particle Size and Mass Spectra Signals - (단일입자 질량분석기를 애용한 서브마이크론 입자의 특성화(I) - 입자의 크기와 질량분광신호의 비선형성 -)

  • Zachariah Michael R.;Lee Donggeun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.29 no.4
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    • pp.453-459
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    • 2005
  • In this paper, we are proposing a robust tool which is capable of measuring the size and elemental composition of submicron particles from twenty to several hundreds nanometers at the same time, i.e., named Single Particle Mass Spectrometer (SPMS). The home-made SPMS employs a laser ablation/multi-photon ionization method to tear a nanoparticle into the constituent elemental ions. One thing different from the conventional Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) is the power of the ionization laser. Much strong laser used in this work makes it possible to generate elemental ions rather than molecular ions from a nanoparticle. Also the use of high power laser may guarantee a complete ionization of a particle, which was confirmed by the existence of multiple charged ions. If a particle is evaporated/ionized completely and detected through electric field-free TOF tube without any loss, we can extract the original particle volume from the measured total ion numbers. Collecting a number of particles mass spectra, we get a database of size and elemental composition of nanoparticles, with which we may take a took into any kinds of chemical reaction occurring at nanoscale. Several issues related to size estimation by SPMS will be discussed.

On the two different sequences of the mass-size relation for early-type galaxies

  • Kim, Jin-Ah;Yoon, Suk-Jin
    • The Bulletin of The Korean Astronomical Society
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    • v.40 no.2
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    • pp.48.3-49
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    • 2015
  • Scaling relations of early-type galaxies (ETG) provide a deep insight into their formation and evolution. Interestingly enough, most relations extending into the dwarf regimes display non-linear or broken-linear features, unlike the linear relations for normal (i.e., intermediate-mass to giant) ETGs only. Here we investigate the mass-size scaling relation of ETGs using a massive database of galaxies from SDSS DR12. We divide ETGs into two groups by the indication of star formation such as colors, and examine their distinction along the mass-size relation. We find that the mass-size distribution of blue, young normal galaxies is in good agreement with that of dwarf ETGs. Our result suggests that blue, young normal ETGs may serve as links between (passive) normal ETGs and dwarfs. We discuss the possibility of blue, young ETGs being progenitors of dwarf ETGs.

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Characterization of Total and Size-Fractionated Manganese Exposure by Work Area in a Shipbuilding Yard

  • Jeong, Jee Yeon;Park, Jong Su;Kim, Pan Gyi
    • Safety and Health at Work
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    • v.7 no.2
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    • pp.150-155
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    • 2016
  • Background: Shipbuilding involves intensive welding activities, and welders are exposed to a variety of metal fumes, including manganese, that may be associated with neurological impairments. This study aimed to characterize total and size-fractionated manganese exposure resulting from welding operations in shipbuilding work areas. Methods: In this study, we characterized manganese-containing particulates with an emphasis on total mass (n = 86, closed-face 37-mm cassette samplers) and particle size-selective mass concentrations (n = 86, 8-stage cascade impactor samplers), particle size distributions, and a comparison of exposure levels determined using personal cassette and impactor samplers. Results: Our results suggest that 67.4% of all samples were above the current American Conference of Governmental Industrial Hygienists manganese threshold limit value of $100{\mu}g/m^3$ as inhalable mass. Furthermore, most of the particles containing manganese in the welding process were of the size of respirable particulates, and 90.7% of all samples exceeded the American Conference of Governmental Industrial Hygienists threshold limit value of $20{\mu}g/m^3$ for respirable manganese. Conclusion: The concentrations measured with the two sampler types (cassette: total mass; impactor: inhalable mass) were significantly correlated (r = 0.964, p < 0.001), but the total concentration obtained using cassette samplers was lower than the inhalable concentration of impactor samplers.

Optimum Radius Size between Cylindrical Ion Trap and Quadrupole Ion Trap

  • Chaharborj, Sarkhosh Seddighi;Kiai, Seyyed Mahmod Sadat;Arifin, Norihan Md;Gheisari, Yousof
    • Mass Spectrometry Letters
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    • v.6 no.3
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    • pp.59-64
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    • 2015
  • Quadrupole ion trap mass analyzer with a simplified geometry, namely, the cylindrical ion trap (CIT), has been shown to be well-suited using in miniature mass spectrometry and even in mass spectrometer arrays. Computation of stability regions is of particular importance in designing and assembling an ion trap. However, solving CIT equations are rather more difficult and complex than QIT equations, so, analytical and matrix methods have been widely used to calculate the stability regions. In this article we present the results of numerical simulations of the physical properties and the fractional mass resolutions m/Δm of the confined ions in the first stability region was analyzed by the fifth order Runge-Kutta method (RKM5) at the optimum radius size for both ion traps. Because of similarity the both results, having determining the optimum radius, we can make much easier to design CIT. Also, the simulated results has been performed a high precision in the resolution of trapped ions at the optimum radius size.

Realistic Analysis Method for Continuously Block-Placed Mass Concrete Structures Considering Block Size and Sequence of Concrete Placement (매스 콘크리트 구조물의 연속 분할타설시 타설블록의 크기 및 타설순서를 고려한 합리적인 수화열 해석)

  • 오병환;전세진;유성원
    • Journal of the Korea Concrete Institute
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    • v.11 no.3
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    • pp.59-67
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    • 1999
  • The mass concrete structures are generally constructed in an incremental manner by deviding the whole structures by a series of many blocks. The temperature and stress distributions of any specific block are continuously affected by the blocks placed before and after the specific block. For an accurate analysis of mass concrete structures, the sequence of all the blocks must be accordingly considered including the change of material properties with time for those blocks considered. The purpose of this study is to propose a realistic analysis method which can take into account not only the influence of the sequence, time interval and size of concrete block placement on the temperatures and stresses, but also the change of material properties with time. It is seen from this study that the conventional simplified analysis, which neglects material property changes of some blocks with time and does not consider the effect of adjacent blocks in the analysis, may yield large discrepancies in the temperature and stress distributions of mass concrete structures. This study gives a method to choose the minimum number of blocks required to obtain reasonably accurate results in analysis. The study provides a realistic method which can determine the appropriate size and time interval of block placement, and can be efficiently used in the design and construction of mass concrete structures.