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Characteristic of Hyperfine Magnesioferrite Particles Possessing Shape Anisotropy
Yim, Going,Yim, Chai-Suck 배재대학교 공학연구소 2005 공학논문집 Vol.7 No.1
The ferrimagnetic resonance technique, with the inclusion of shape anisotropy effects, was used to obtain information about the early stages in the precipitation of magnesium ferrite from iron-doped magnesia. The very small magnesioferrite particles were produced by precipitation method from solid solution of iron ion in single crystal magnesia. The temperature dependence of the resonance anisotropy field for a coherent assembly of hyperfine magnesium ferrite precipitates was investigated in the range 100~400K. The results are interpreted in terms of the shape anisotropy of the precipitates.
Evaluation of an Ammonia Passive Sampler Using Chamber System
Yim, Bong-Been,Kim, Sun-Tae Korean Society for Atmospheric Environment 2006 한국대기환경학회지 Vol.22 No.E1
The purpose of this study was to evaluate the efficiency of a passive sampler in measuring atmospheric ammonia concentrations using chamber system. The ability of the passive sampler to quantitatively determine atmospheric ammonia gas was almost identical to that of the reference method (indophenol method). There was no significant difference between concentrations measured by the two methods. The detection and quantification limits of the ammonia passive sampler were 16.9 ppb and 25.3 ppb, respectively, for a 24-h sampling period. The average coefficient of variation between replicated samplers was $6.7{\pm}4.2%$. The concentrations measured by the two methods (passive sampler and indophenol method) were no significant difference with good a correlation (correlation coefficient=0.964).
Volatile Organic Compounds Measurement In The Boundary Of Waste Treatment Facilities
Bong Been Yim,Sun Tae Kim 대한환경공학회 2007 Environmental Engineering Research Vol.12 No.2
Concentrations of the principal volatile organic compounds, such as benzene, toluene, ethylbenzene, m,p,o-xylene, styrene, and chlorobenzene were measured at the solid waste treatment plants classified into four categories; municipal waste incinerator, municipal waste landfill site, industrial waste incinerator and industrial waste landfill site. The average concentration of VOCs in industrial waste treatment facilities was 33.43 ppb and was significantly higher than that measured at municipal waste treatment facilities (4.71 ppb). The average toluene concentrations measured at incinerators (13.05 ppb) were a little higher than those measured at landfill sites (11.54 ppb). The contribution of the waste treatment facilities to the concentration of benzene (0.35 ppb) and o-xylene (0.15 ppb) in the industrial area was relatively small. However, toluene measured in the industrial waste treatment facilities was the most abundant VOCs with the average concentration of 21.37 ppb. As a result of analyses of fingerprint, in cases of IISH and ILUS, a variety of compounds other than major VOCs were detected in high level. On the Pearson correlation analysis, the correlation was generally positive and some pairs of these VOCs were very strongly correlated (correlation coefficient > 0.75).
Evaluation of Badge-Type Diffusive Sampler Performance for Measuring Indoor Formaldehyde
Bong Been Yim,Kyu Sung Lee,Joo In Kim,Hyun Su Hong,Sun Tae Kim 대한환경공학회 2013 Environmental Engineering Research Vol.18 No.3
The purposes of this study were to determine the efficiency of using a badge-type diffusive sampler to measure formaldehyde concentrations indoors, and to evaluate the uncertainty associated with the use of data from a diffusive sampler. A diffusive sampler using 2,4-dinitrophenylhydrazine (DNPH) reagent was found to be a suitable tool for measuring the formaldehyde concentration in an indoor environment. The agreement between results of the diffusive sampler and DNPH cartridge were good, showing a correlation coefficient of 0.996. The sampling rate for the diffusive sampler was calculated to be 1.428 L hr.1, with a standard deviation of 0.084 L hr.1. It was found through analysis that the uncertainty associated with the sampling rate and the mass of the formaldehyde transported into the diffusive sampler by diffusion was the dominant contributor to the total.