• Spatial Information Research
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• v.20 no.2
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• pp.117-127
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• 2012

The purpose of this study is to develop the auto-building algorithm of the Geometric Network Model(GNM), a topology model including geometric information because of the need to reflect the features' geometric characteristic into the topology model, which is for development of indoor 3D virtual model enabling queries. As the critical algorithm, the Straight Medial Axis Transformation(SMAT) algorithm is proposed in order to automatically extract the medial axis of features. The SMAT algorithm is generalized from the existing S-MAT algorithm and a range of target features where applicable is extended from simple polygons to weakly simple polygons which mean the polygons containing the inner ring inside. The GNM built automatically is finally printed out as the .csv file for easy access and w ide application in other systems. This auto-building algorithm of the GNM is available for plenty of cases such as finding a shortest path, guiding a route in emergency situation, and semantic analysis.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.2
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• pp.148-155
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• 2013

Objectives: This study was performed in order to compare the average levels and similarity of occupational exposure limits in South Korea, the U.S., the E.U., Germany, Japan and Finland. Methods: In this study, occupational exposure limits (OELs) for one hundred and seventy seven hazardous substances which are managed in the workplace by the Occupational Safety and Health Act in South Korea were matched with those of other countries. The units for the exposure limits of the same substance (identical CAS number) were unified and the exposure limits in each country were compared with threshold limit values (TLVs) of the American Conference of Governmental Industrial Hygienists (ACGIH) using a geometric mean method. Geometric similarity was calculated to assess the association by each country. Results: The exposure limits according to ACGIH TLVs in South Korea, the E.U., Germany, Japan, and Finland were 148, 37, 76, 90, and 110, respectively. When using TLVs of ACGIH as a standard, the geometric mean ratios of Germany, Finland, the E.U., South Korea, and Japan were 0.79, 0.80, 0.82, 1.19, and 1.27, respectively. Geometric similarity with TLVs of ACGIH was highest in South Korea (0.75) followed by Japan (0.56), the E.U. (0.52), Finland (0.50), and Germany (0.46). Conclusions: Through the comparison of levels of OELs and similarities among South Korea, the U.S., the E.U., Germany, Japan, and Finland, we could better understand the characteristics of occupational exposure limits by country.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.3
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• pp.192-202
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• 2010

This study aimed to suggest the severity of indoor air pollutants in screen gold arenas which were not sufficiently investigated in Korea up to now and to help users to enjoy golf in more pleasant indoor environment. The indoor environment survey was conducted with 21 screen gold arenas in Seoul from Oct. 28, 2008 to March 13, 2009. Indoor air quality was measured and analyzed in accordance with the Air Pollution Process Test Method specified bu NIOSH(2005). The screen golf arenas are mostly in the underground floors in this study, 4 on the ground floors(19.0%) and 17 in the underground floors(81.0%). In the air in screen golf arenas, the geometric mean of benzene, toluene, ethylbenzene and xylene were 2.92 ${\mu}g/m^3$, 70.34 ${\mu}g/m^3$, 14.00${\mu}g/m^3$ and 31.43 ${\mu}g/m^3$, respectively, which exceeded the exposure limites. Each arena exceeded the exposure limit for one pollutant each. However, styrene didn't exceed the limit as 8.09 ${\mu}g/m^3$. Furthermore, the geometric mean of formaldehyde was 63.11${\mu}g/m^3$ and 7 arenas exceeded the limit. The geometric mean of volatile organic compounds(VOCs) was 428.41${\mu}g/m^3$ and 10 arenas exceeded the limit. For the density distribution of pollutants by location, benzene, toluene, ethylbenzene, xylene, styrene and formaldehyde showed higher density distribution in underground spaces, for which the statistically significant difference was not found. However, PM10 showed the statistically significant difference (p<0.05). In accordance with the analysis on the correlation between the density of pollutants in the screen golf arenas, Pearson correlation coefficient between ethylbenzene and styrene was 0.980, very significant correlation(p<0.01). The correlation coefficients between the density of toluene, ethylbenzene, xylene and styrene and that of VOCs were 0.543, 0.434, 0.451 and 0.459, respectively, which demonstrated the statistically significant difference (p<0.05).

• Journal of Environmental Health Sciences
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• v.36 no.3
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• pp.199-207
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• 2010

In this study, breast milk levels of indicator polychlorinated biphenyls (PCBs) were estimated, and statistics drawn, for 22 Koreans in the general population, aged 26-38, who had resided in metropolitan areas for more than 5 years without occupational exposure to organochlorine pollutants. Concentrations of indicator PCBs were measured using the isotope dilution method with a high resolution gas chromatograph/high resolution mass detector, which provided accurate and precise data for investigation of trends, and international comparisons. The geometric mean of total indicator PCB levels was 22.3 ng/g lipid, which is significantly lower than the level in individuals from European countries. Overall, the geometric mean and 95th percentile of the most abundant congener PCB 153 were 8.04 ng/g lipid and 16.4 ng/g lipid, respectively. PCB congeners 138, 153 and 180 together accounted for about 75% of the indicator congeners analyzed. Breast milk total indicator PCB concentrations were significantly associated with age and parity, but not with body mass index (BMI), rate of body weight increase, or smoking habits. The geometric mean level of PCB 153 in breast milk from mothers with a pre-pregnant BMI < $21\;kg/m^2$ was significantly higher than in pre-pregnant women with a BMI of ${\geqslant}\;21\;kg/m^2$ (p<0.05). Women who ate more fish, meat, and milk products did not have significantly higher total indicator PCB levels than those who ate less of these products, but a significant difference in PCB 153 levels was demonstrated between the subjects consuming higher (11.45 ng/g lipid) and lower (6.79 ng/g lipid) amounts of fish (p<0.05), after adjusting for confounders. These results suggest that age, parity and fish intake are the important factors affecting the concentrations of indicator PCBs in these subjects.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.6 no.2
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• pp.272-280
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• 1996

This study was to evaluate the associations between urinary S-Phenyl-mercapturic acid(S-PMA) as a new indicator of biological monitoring for low level of exposure to benzene and independent variables such as the air concentration of benzene in the breathing zone of workers, the years of work, and smoking. In this study the subjects were the total of 145 drawn from 53 workers who were occupationally exposed to benzene and 92 workers who were not. The results were as follows: 1. In the workplace geometric mean concentration of benzene in the breathing zone of workers was 0.31 ppm(0.02 - 3.26 ppm) for the spraying workers and 0.25 ppm(0.02 - 3.95 ppm) for the printing workers. 2. The geometric mean of uninary S-PMA for non exposed group was $8.9{\mu}g/g$ creatinine($0.6-72.3{\mu}g/g$ creatinine), 80.3% (74 workers) of the total non-exposed workers indicated less than $20{\mu}g/g$ creatinine of uninary S-PMA. The difference of uninary S-PMA by sex, age, smoking was not significant. 3. The geometric mean of urinary S-PMA for workers who were exposed to benzene was $37.2{\mu}g/g$ creatinine, and was four times higher than that of workers who were not exposed. And 79.3% (42 workers) of the total exposed workers indicated more than $20{\mu}g/g$ creatinine of urinary S-PMA. 4. Regarding the level of benzene in the air, urinary S-PMA was the highest level of $147.9{\mu}g/g$ creatinine in the workers who were exposed to air concentration of 0.5 ppm of benzene and was higher as the level in the air was increased. 5. The correlation coefficient between log urinary S-PMA and log benzene concentration in the breathing zone was 0.80, and the following linear equation was found between urinary log S-PMA and log benzene concentration in the breathing zone : log S-PMA(${\mu}g/g$ creatinine) = 0.564 log benzene in air(ppm) + 0.192 (n=53, r=0.80, p=0.000) In conclusion, the concentration of S-PMA in urine proved to be good parameter for biological monitoring benzene exposure at the workplace even at low level of benzene in air.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.1143-1153
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• 2018

For TOPS InSAR processing, high-precision image co-registration is required. We propose an image co-registration method suitable for the TOPS mode by comparing the performance of cross correlation method, the geometric co-registration and the enhanced spectral diversity (ESD) matching algorithm based on the spectral diversity (SD) on the Sentinel-1 TOPS mode image. Using 23 pairs of interferometric pairs generated from 25 Sentinel-1 TOPS images, we applied the cross correlation (CC), geometric correction with only orbit information (GC1), geometric correction combined with iterative cross-correlation (GC2, GC3, GC4), and ESD iteration (ESD_GC, ESD_1, ESD_2). The mean of co-registration errors in azimuth direction by cross correlation and geometric matching are 0.0041 pixels and 0.0016 pixels, respectively. Although the ESD method shows the most accurate result with the error of less than 0.0005 pixels, the error of geometric co-registration is reduced to 0.001 pixels by repetition through additional cross correlation matching between the reference and resampled slave image. The ESD method is not applicable when the coherence of the burst overlap areas is low. Therefore, the geometric co-registration method through iterative processing is a suitable alternative for time series analysis using multiple SAR data or generating interferogram with long time intervals.

• Communications of the Korean Mathematical Society
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• v.24 no.3
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• pp.361-366
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• 2009

In this paper we consider constructive function triples on the real numbers $\mathbb{R}$ and on (not necessarily commutative) integral domains D which permit the construction of a multitude of d-algebras via these constructive function triples. At the same time these constructions permit one to consider various conditions on these d-algebras for subsets of solutions of various equations, thereby producing geometric problems and interesting visualizations of some of these subsets of solutions. In particular, one may consider what notions such as "locally BCK" ought to mean, certainly in the setting provided below.

• Journal of the Korean Data and Information Science Society
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• v.8 no.2
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• pp.261-270
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• 1997

This paper is proposed the parametric empirical Bayes(EB) confidence intervals which corrects the deficiencies in the naive EB confidence intervals of the scale parameter in the Weibull distribution under item-censoring scheme. In this case, the bootstrap EB confidence intervals are obtained by the parametric bootstrap introduced by Laird and Louis(1987). The comparisons among the bootstrap and the naive EB confidence intervals through Monte Carlo study are also presented.

• Communications for Statistical Applications and Methods
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• v.7 no.2
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• pp.549-562
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• 2000

Default Bayes factors are computed to test the equality of one Poisson population mean and the equality of two independent Possion population means. As default priors are assumed Jeffreys priors, noninformative improper priors, and default Bayes factors such as three intrinsic Bayes factors of Berger and Pericchi(1996, 1998), the arithmetic, the median, and the geometric intrinsic Bayes factor, and the factional Bayes factor of O'Hagan(1995) are computed. The testing results by each default Bayes factor are compared with those by the classical method in the simulation study.

• Communications of the Korean Mathematical Society
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• v.12 no.4
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• pp.985-998
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• 1997

For n random strips chosen so as to meet a fixed bounded convex set K of the plane we let $\nu$ be the number of intersection regions that meet K. We develop the integral formula for the mean value of $\nu$ and $\nu^2$ involving the area and the perimeter of K and the breadths of the strips. We get some geometric inequalities in way of studying integral geometry.