• Journal of Korean Society for Atmospheric Environment
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• v.15 no.2
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• pp.79-87
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• 1999

$^{239+240}Pu$ concentrations in precipitation were determined for the period of May 1994 to August 1996 in oder to describe current $^{239+240}Pu$ deposition at the mid-western coat of Korea (Ansan, 37$^{\circ}$17'N, $126^{\circ}$50'E). $^{239+240}Pu$ concentration in daily precipitation varied from 0.05 to 131$\mu$Bq $kg^{-1}$ with a geometric mean of $1.26\mu$Bq $kg^{-1}$. The concentration was high in the period of Yellow Sand Storm in spring and low in wet summer monsoon. The specific $^{239+240}Pu$ concentration in daily precipitation appears to be controlled by the $^{239+240}Pu$ input to the atmosphere in spring and washout effects by precipitation in the wet summer monsoon. Wet depositional flux of $^{239+240}Pu$ varied from 4 to 123$\mu$Bq $m^{-2}d^{-1}$ with a geometric mean of $33.8\mu$Bq $m^{-2}d^{-1}$ and with a maximum in the period of Yellow Sand Storm and a minimum in the period of wet summer monsoon. $^{238}Pu$/$^{239+240}Pu$ activity raios(0.04~0.31) in precipitation for March-June period suggested that one of the major sources of Pu isotopes falling in Ansan area is the arid region of the Chinese continent.

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.3
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• pp.34-44
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• 1986

Particle size distribution of airborne suspended particulate concentrations according to particle size in the events of yellow sand phenomena, have been measured and analyzed by using Andersen air sampler for four years, January 1982 through December 1985. The conclusions are as follows: 1. Yellow sand phenomena, generally, occur between March and May. 2. The frequent occurrences of yellow sand were observed during March and April and airborne suspended particulate concentrations in the cases of yellow sand appeared to be 2 $\sim$ 3.4 times higher than those of normal conditions. 3. Geometric mean particle diameter and its geometric mean standard deviation by logarithmic normal distribution sheet, were quite close to each other and log-distribution curves showed similar shapes. 4. Analysis by particle size distribution curve showed bi-modal distribution. 5. Concentrations of coarse particles in normal conditions were 1.2 $\sim$ 2 times higher than those of fine particles and, similarly, coarse particle concentrations in yellow sand cases were 1.3 $\sim$ 2.5 times higher than those of fine particles. 6. Concentrations of coarse particles in yellow sand cases were 2 $\sim$ 3.6 times higher than those in normal conditions and those of fine particles were 1.7 $\sim$ 3.5 times higher.

• Journal of Environmental Health Sciences
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• v.27 no.4
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• pp.51-62
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• 2001

Geometric mean of airborne welding fume concentration at technical high schools was 4.80mg/㎥)N.D~35.39 mg/ ㎥ and the percentage of samples exceeded TLV of the Korean ministry of labor was 43.6%, Geometric mean of airborne Mn concentration was 0.06 mg/㎥(N.D~0.42mg/㎥) and the percentage of samples exceeded TLV of ACGIH was 15.4 % In case of airborne Me concentration, there is a significant difference among schools (p<0.05) Mn concentrations in blood of the exposed and control groups were 1.84$\mu\textrm{g}$/dl and 1.91 mg/dl respectively. Mn concentrations in urine of the exposed and control groups were 1.36$\mu\textrm{g}$/ιand 0.57$\mu\textrm{g}$/ι respectively. In case of Mn concentrations in urine there is a significant difference between both groups(P<0.001) and among schools(p<0.05) Mn concentrations in blood and urine of exposed group were not over BEIs of the Korean ministry of labor. Mn levels in blood and urine were not significantly affected by smoking, drinking and residence, There was no correlation between Mn concentration in air and blood but there was a statistically significant correlation between Mn concentration in air urine(r=0.323). There was no a statistically significant correlation between Mn concentration in blood and urine.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1C
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• pp.1-7
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• 2011

Recently, multi-hop relay transmission has drawn much attention owing to its advantage of coverage extension at low power consumption. In this paper, we derive a performance bound of multi-hop communication systems with multiple amplify-and-forward relays when the optimal path is selected. The bound is derived in generalized Nakagami fading channels with different parameters for each hop by applying the geometric mean bound to the path signal-to-noise ratio (SNR) and obtaining the moment generation function of the bound. It is shown that the bound based on the geometric mean is closer to the actual performance of optimal path selection when the fading effect is small.

• Korean Journal of Veterinary Research
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• v.19 no.1
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• pp.45-51
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• 1979

The present study was undertaken to observe the immune status of breeding hens and laying hens against Newcastle disease (ND). The methods of extraction of hemagglutination inhibition (HI) antibody from egg yolk, the detection of HI antibody in egg albumen and the correlation between HI antibody titers in maternal sera and egg yolks were discussed. For the purposes of these experiments, 9 flocks of breeding hens and 16 flocks of laying hens immunized against Newcastle disease virus were investigated. The vaccination program of tested flocks was 3-3-3 or 4-4-4 in general. The results obtained are summerized as follows: Freezing-thawing was the best method far antibody extraction from egg yolk for HI test. The HI antibody against NDV was found in egg albumen (geometric mean, 4.5), but lower than that found in egg yolk (32.1). The geometric mean of HI antibody titers of egg yolks (84.1) was higher than that of maternal sera (68.4) and day-old chicken sera (25.3). There was correlation between HI antibody titers of maternal sera(Y) and those of egg yolks(X). The coefficient correlation was r=0.63, and the line of regression of Y on X was $\hat{Y}$=35.91+0.35X.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.2
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• pp.166-173
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• 2015

Objectives: The purpose of this study was to evaluate cobalt concentrations in airborne inhalable, total and respirable dust from manufacturing industries using cobalt. Methods: To compare cobalt concentrations, three types of dust samplers(a 37mm closed cassette sampler, Institute of Occupational Medicine(IOM) sampler, and Aluminum cyclone sampler) were used. The analysis of cobalt concentrations was conducted using AAs based on the NIOSH 7300 method. Results: The geometric mean of cobalt concentration in total dust was $1.47{\mu}g/m^3$, and the rate of excess of the Korean Occupational Exposure Limit(KOEL) was 10.0%. The geometric mean concentrations of cobalt in super alloy manufacturing industries were higher than those in plating industries, and molding operations showed higher exposure levels to cobalt than did other operations. Conclusions: The rate of cobalt concentration in inhalable dust from super alloy manufacturing industries exceeding the Workplace Exposure Limit(WEL) as recommended by the Health & Safety Executive(HSE) was 7.1%, which means proper work environmental management is required through wet work environments. Given that molding operations had higher cobalt concentrations, it is necessary to apply measures such as local exhaust for reducing airborne dust in cobalt manufacture industries.

• Korean Journal of Remote Sensing
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• v.36 no.4
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• pp.503-513
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• 2020

This paper presents a method to evaluate denoising filters based on edge locations in their denoised images. Image quality assessment has often been performed by using structural similarity (SSIM). However, SSIM does not provide clearly the geometric accuracy of features in denoised images. Thus, in this paper, a method to localize edge locations with subpixel accuracy based on adaptive weighting of gradients is used for obtaining the subpixel locations of edges in ground truth image, noisy images, and denoised images. Then, this paper proposes a method to evaluate the geometric accuracy of edge locations based on root mean squares error (RMSE) and jaggedness with reference to ground truth locations. Jaggedness is a measure proposed in this study to measure the stability of the distribution of edge locations. Tested denoising filters are anisotropic diffusion (AF), bilateral filter, guided filter, weighted guided filter, weighted mean of patches filter, and smoothing filter (SF). SF is a simple filter that smooths images by applying a Gaussian blurring to a noisy image. Experiments were performed with a set of simulated images and natural images. The experimental results show that AF and SF recovered edge locations more accurately than the other tested filters in terms of SSIM, RMSE, and jaggedness and that SF produced better results than AF in terms of jaggedness.

• Journal of the Korea Safety Management & Science
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• v.14 no.3
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• pp.135-141
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• 2012

This study was conducted to evaluate the characteristics of exposure to asbestos for ship repair workers in Korea by a systematic review. The number of articles studying asbestos exposure levels from ship repair workplaces was found to be 4. All asbestos concentration reported as either geometric mean and geometric standard deviation or ranges were transformed to arithmetic mean to estimate exposure level. In addition, weighted arithmetic means(WAMs) were calculated by weighing of the different number of samples. The WAM concentrations were 2.746 f/cc during asbestos dismantling work, 0.034 f/cc before asbestos dismantling work and 0.065 f/cc after working respectively. The maximum airborne concentration of asbestos during asbestos removal work was 7.02 f/cc which was 70 times higher than the occupational exposure limit of Korea, 0.1 f/cc. This study recommends that retrospective exposure to asbestos based on various ship types and operations should be assessed.

• Asian Journal of Atmospheric Environment
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• v.7 no.1
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• pp.56-63
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• 2013

Children are particularly vulnerable to adverse health effects associated with heavy metal exposure. The goal of this study was to investigate the relationship between proximity to an industry complex and blood lead and urinary cadmium levels for children aged 7-13 who lived in Ulsan where a big petrochemical complex is located. We conducted a questionnaire survey to collect data including sociodemographics, daily habits, residential environment, etc. We also analyzed blood lead and urinary cadmium levels using Atomic Absorption Spectrometry (AAS). Data were analyzed using regression analysis. All statistical analyses were conducted with SAS software version 9.2. We calculated distance by using a Geographic Information System (ArcGIS version 10.0). The geometric mean blood lead level was 1.55 ${\mu}g/dL$ (boys: 1.59 ${\mu}g/dL$, girls: 1.51 ${\mu}g/dL$), and the geometric mean urinary cadmium level was 0.51 ${\mu}g/g$ creatinine (boys: 0.45 ${\mu}g/g$ creatinine, girls: 0.58 ${\mu}g/g$ creatinine). In the results of regression analyses, we found that urinary cadmium levels significantly decreased as distance between residence and industrial complex increased after adjusting for age, gender, income, passive smoking and the length of residence. This result was opposite to that for lead levels. Our observations support the hypothesis that urinary cadmium levels in children are related to their proximity to an industrial complex.

• Environmental Engineering Research
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• v.24 no.4
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• pp.572-581
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• 2019

The emission of hydrogen sulfide (H₂S) from the Kahrizak landfill was studied. Firstly, the field measurements were conducted in the summer and winter seasons; and the samples were analyzed using Jacob method. We predicted the H₂S concentrations in the downwind using AERMOD and ISCST3. According to the AERMOD, the maximum concentration of H₂S in the summer and winter were 117 ㎍/㎥ and 205 ㎍/㎥ respectively. The downwind concentrations reached zero at the distance of 35 km from the leachate treatment plant. The Geometric mean bias, Geometric variance, Fractional bias, Fraction of predictions within a factor of two of the observations and Normalized mean square error for the AERMOD were 0.58, 1.35, -0.12, 1.91 and 0.042, respectively in the summer and 1.39, 1.35, -0.05, 1.46 and 0.027 in the winter; and for the ISCST3, were 0.85, 1.03, 0.02, 1.45 and 0.04 in the summer and 1.18, 1.03, 0.15, 1.16 and 0.04 in the winter. The results of the AERMOD were compared with the ISCST3 and indicated that the AERMOD performance was more suitable than the ISCST3.