• Journal of Korean Society for Atmospheric Environment
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• v.27 no.1
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• pp.97-116
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• 2011

This study analyzed indoor air pollutants from elementary school with different environment. Air sampling and measurement were carried out from classrooms and hallways from three target elementary schools in the fall and winter seasons. The winter average concentrations of $PM_{10}$, $CO_2$, CO, aldehydes and ketones, and benzene were higher than the fall ones. The fall average concentrations of $O_3$ and $NO_2$ were higher than the winter ones. The concentrations of $PM_{10}$ and $CO_2$ at the schools near the heavy traffic areas and having poor ventilation were higher than those from the other elementary school. The average concentration of CO at the school having heavy traffic volume was highest. The concentrations of $O_3$, $NO_2$, aldehydes and ketones, and VOCs at the school near the shipbuilding industries were highest among the three elementary schools.

• Environmental Engineering Research
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• v.15 no.2
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• pp.93-98
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• 2010

This study aims to determine the chemical composition and seasonal variation of atmospheric acid deposition in order to identify possible sources contributing to precipitation. Sampling and analysis of 132 wet deposition samples were carried out from January to December 2008 at Mae Hia Research Center, Chiang Mai University, Chiang Mai Province. Total precipitation was 1,286.7 mm. Mean electro-conductivity and pH values were 0.94 mS/m and 6.27, respectively. Major cations ($Na^+$, ${NH_4}^+$, $K^+$, $Ca^{2+}$, and $Mg^{2+}$) and major anions ($HCOO^-$, $CH_3COO^-$, $Cl^-$, ${NO_3}^-$, and ${SO_4}^{2-}$) were determined by Ion Chromatography. The relative volume weight mean concentrations of anions, in descending order, were ${SO_4}^{2-}$ > ${NO_3}^-$ > $Cl^-$ > $CH_3COO^-$ > $HCOO^-$ and those of cations were $NH_4^+$ > $Ca^{2+}$ > $Mg^{2+}$ > $K^{+}$ > $Na^+$. Results of a principle component analysis highlighted the influence of various possible sources of ions such as agricultural activity, fuel combustion, marine sources, soil resuspension, and biomass burning.

• Journal of the Korea Computer Graphics Society
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• v.8 no.2
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• pp.9-14
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• 2002

In cases of densely occluded urban scenes, it is effective to determine the visibility of scenes, since only small parts of the scene are visible from a given cell. In this paper, we introduce a new visibility preprocessing method that efficiently computes potentially visible objects for volumetric cells. The proposed method deals with general 3D polygonal models and invisible objects jointly blocked by multiple occluders. The proposed approach decomposes volume visibility into a set of point visibilities, and then computes point visibility using hardware visibility queries, in particular HP_occlusion_test and NV_occlusion_query. We carry out experiments on various large-scale scenes, and show the performance of our algorithm.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.3
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• pp.326-333
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• 2003

In the measurement using DMA and CPC in series, there is some time delay for particles classified in DMA to detect in CPC. During this time, the DMA time-response changes due to the velocity profile of sampling tube and the diffusion of particles in the volume that exists between the DMA exit and the detector of ultra-fine CPC. This is called mixing effect. In the accelerated measurement methods like the TSI -SMPS, the size distribution is obtained from the correlation between the time-varying electrical potential of the DMA and the corresponding particle concentrations sampled in DMA. If the DMA time -response changes during this delay time, this can cause the error of a size distribution measured by this accelerated technique. The kernel function considering this mixing effect using the residence time distribution is proposed by Russell et al. In this study, we obtained a size distribution using this kernel to compare to the result obtained by the commercial accelerated measurement system, TSI -SMPS for verification and considered the errors that result from the mixing effect with the geometric mean diameters of originally sampled particles, using virtually calculated responses obtained with this kernel as input data.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.1
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• pp.1-8
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• 2016

Optical particle sizer (OPS), optical particle counter (OPC), and aethalomter were deployed to measure the particle number concentrations from 0.3 to $10.0{\mu}m$ and black carbon (BC) concentrations. Comparisons of particle number concentrations measured by OPS and OPC were conducted to evaluate the performance of the each optical instrument at the Gwangju sampling site ($35.23^{\circ}N$, $126.84^{\circ}E$) for 14 days from Dec. 27 in 2014. Although a good correlation ($r^2=0.99$) between the OPS and OPC was observed for both the particle number and volume concentrations, different relationships by BC concentrations can be associated with the intensities by different light scattering angles. In addition, based on diurnal patterns of size distributions in 24 hr running correlation coefficient determination, BC concentrations were highly related to the particles less than $0.3{\mu}m$ observed in the morning traffic hour.

• Journal of Korea Water Resources Association
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• v.33 no.1
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• pp.73-85
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• 2000

A water quality model was developed for small stream at a upland agricultural watershed. A control volume method was employed to digest the severe variability of stream shape, water quality and discharge at small streams. We estimated optimum reaction coefficients and model structure using a random number generation technique. The index of agreement and coefficient of efficiency were introduced for the model calibration criterion. As the result, the reliability of model parameter estimation could be improved. The applicability of model was tested by a set of sampling results at Yongduckchun in Kimhae. The variability of water quality reaction coefficient was explored through the observed data and using the developed model. model.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.10a
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• pp.160-161
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• 2003

In Korea, 1, 357 tonnes of benzoyl peroxide was produced as a white granule with purities ranging 22 to 95％ in 2001. 75% of benzoyl peroxide is mainly used in the manufacture of expandable styrene polymer and other resins as initiators of polymerization and also been used in the treatment of acne vulgaris and the medical product contains mainly 5 to 10% of it. A very small portion of benzoyl Peroxide is used as flour bleaching agent, Potential human exposure from workplaces is expected to be negligible because this chemical is produced in closed system in only one company in Korea and when a production facility monitors its workplace for the worker exposure annually, the concentration of airborne aerosols at the personal sampling has been less than 1mg/㎥.

• Analytical Science and Technology
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• v.5 no.3
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• pp.269-276
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• 1992

An ion-exchange/conductometric method is applied for the determination of total acidity in simulated atmospheric samples. Non-$H^+$ cations and strong acid anions are enriched by the preconcentrator columns in series and eluted through the corresponding parallel suppressor units. The conductivities from each channel correspond to the concentrations of the resulting ionized species in equivalents per unit volume. The difference is the measure of acidity due to strong acids. With 5-min sampling at a flow rate of 0.3 mL/min, the detection limits for ${NH_4}^+$ and ${SO_4}^{2-}$ are 0.3 and $0.1{\mu}equiv/L$, respectively. The acidity for samples composed of various ions can be determined without significant error, usually less than 5%. The proposed method discriminates against the artifact from the $CO_2$ dissolution. Principles of acidity measurements are also presented.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.2
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• pp.191-198
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• 1995

In order to evaluate the distribution and behaviour of atmospheric particulate metals in high-altitude area, we collected 22 aerosol samples using a high volume air sampler at Soback Mt. Meteorological Observation Station from Jan. to Nov. 1993 and analysed for metals (Al, Fe, Mg, Na, Ca, Mn, Co, Ni, Cu, Zn, Cd, and Pb) with ICP/AES and ICP/MS. Although sampling site is located in high-altitude and far from local sources of atmospheric pollutants, enrichments of metals are 2 times higher than those of western coastal reural area. This fact may imply that of metallic pollutants in the coastal rural site were came from further western side (e.g. China), atmospheric metals in this study area contain the signal of metropolitan cities located in the main wind direction (NNW). Sea salts are negligible in the aerosol particle population because reference elements of sea salts (Na, Mg) are all originated from soil particles. The contents of soil particles in aerosols are highest in spring and lowest in winter. Atmospheric enriched elements (Ni, Cu, Zn, Cd and Pb) are diluted with soil particles, especially during the yellow sand period. The results of factor analysis suggest possibility of interpreting their chemical significance in terms of sources (soil, pollutants) and gas-particle conversion processes (formation of ammonium sulfates, ammonium nitrates and/or their mixtures).

• Korean Journal of Veterinary Research
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• v.46 no.4
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• pp.387-393
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• 2006

Progressing to the iron deficiency anemia was experimentally induced in 4 clinically healthy dogs by repeated phlebotomy to characterize hematologic features, serum iron values, and RBC indices. Abnormal RBC morphologies were also evaluated semiquantitatively on Wright's-stained blood films. Hematologic abnormalities in early stage of anemia included decreased both hematocrit and hemoglobin, and reticulocytosis, with no changes in mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) were represented. In intermediate stage, decreased serum iron concentration with microcytosis and hypochromia were prominent. In late stage, red cell distribution width and Mentzer's index were out of reference ranges in the majority of dogs. In this study microcytic anemia was appeared at the hemoglobin range of 5.1-7.2 g/dl. On most sampling days, platelet counts and white blood cells were within the reference ranges, with some minor variations. Iron deficiency was not necessarily associated with microcytic anemia. Judging from the sequential changes of both MCV and MCHC, 3 patterns of anemia were sequentially observed: initially normocytic normochromic, intermediate normocytic hypochromic or normocytic normochormic, and finally microcytic hypochromic. The most frequent morphologic abnormalities were target cells. Occasional elliptocyte, acanthocyte, stomatocyte, kinzocyte, dacrocyte and schistocyte were also noted on the blood films.