• Animal cells and systems
• /
• v.4 no.1
• /
• pp.57-62
• /
• 2000

Soil samples were collected in thirteen Manitoba boreal forest sites. Spatial distribution of chytrids from diverse boreal forest microhabitats was investigated by baiting with jack pine pollen. After baiting, the pollen was surveyed for chytrids for 8 ten day period and individual species were counted. Total infestations of pollen by chytrids ranged from 5.8% to 90.2% from various soils. Each site with high infestation was characterized by litter with high needle content while mineral soil or soil with limited organic matter yielded low levels of pollen infestation. Species diversity tended to be higher in soils with higher pollen infestation and lower in soils with lower pollen infestation. Lower diversity was generally observed in mineral soils or soils with a limited organic horizon comprised, in part, of broad leaf litter. Based on coefficients of association and species in common among species across the collection sites, it was possible to relate dominant species assemblages in site groups. These species assemblages in the site groups suggest that the chytrids are distributed by litter and soil types. It can be concluded that the substratum characteristics of litter types and availability of litter may be important in describing chytrid distribution in boreal forest sites.

• Journal of the Korean GEO-environmental Society
• /
• v.10 no.7
• /
• pp.103-109
• /
• 2009

The probabilistic seismic hazard analysis (PSHA) calculates the probability of exceedance of a certain ground motion parameter within a finite period at a site of interest. PSHA is very robust in that it can account for the uncertainties in seismic source, wave passage effect, and seismic site effects and hence, it is the most widely used method in quantifying the future earthquake induced ground vibration. This paper evaluates the applicability of a new PSHA that is alleged to be able to reproduce the results of a conventional PSHA method, but generates a series of earthquake scenarios and corresponding ground motion time histories that are compatible with the scenarios. In the application, a 40,000 year period is simulated, during which 16,738 virtual earthquakes have occurred. The seismic hazard maps are generated from the outputs of the new PSHA. Comparisons with the maps generated by the conventional PSHA method demonstrated that the new PSHA can successfully reproduce the results of a conventional PSHA. The new PSHA may not be very meaningful in itself. However, the real advantage of the method is that it can be used to develop probabilisitic seismic site coefficients. The suite of generated ground motion time histories are used to develop probabilistic site coefficients in the companion paper.

• Wind and Structures
• /
• v.14 no.4
• /
• pp.301-319
• /
• 2011

The full-scale measurements are compared with the wind tunnel test results for the long-span roof latticed spatial structure of Shenzhen Citizen Center. A direct comparison of model testing results to full-scale measurements is always desirable, not only in validating the experimental data and methods but also in providing better understanding of the physics such as Reynolds numbers and scale effects. Since the quantity and location of full-scale measurements points are different from those of the wind tunnel tests taps, the weighted proper orthogonal decomposition technique is applied to the wind pressure data obtained from the wind tunnel tests to generate a time history of wind load vector, then loads acted on all the internal nodes are obtained by interpolation technique. The nodal mean wind pressure coefficients, root-mean-square of wind pressure coefficients and wind pressure power spectrum are also calculated. The time and frequency domain characteristics of full-scale measurements wind load are analyzed based on filtered data-acquisitions. In the analysis, special attention is paid to the distributions of the mean wind pressure coefficients of center part of Shenzhen Citizen Center long-span roof spatial latticed structure. Furthermore, a brief discussion about difference between the wind pressure power spectrum from the wind tunnel experiments and that from the full-scale in-site measurements is compared. The result is important fundament of wind-induced dynamic response of long-span spatial latticed structures.

• Journal of Korean Society for Atmospheric Environment
• /
• v.22 no.6
• /
• pp.767-778
• /
• 2006

This study was carried out to evaluate the temporal variations of VOCs at an urban site, and to compare the concentrations of VOCs at an urban site in Daegu with those at a suburban site in Gyeongsan. Three hourly VOC samples in the ambient air were collected using a sequential tube sampler (STS 25, Perkin Elmer) throughout two weeks during May and July representing spring and summer seasons, respectively. The VOC concentrations were determined by an automatic thermal desorption apparatus with GC/MS analysis. A total of 12 VOCs of environmental concern were determined, which are chloroform, benzene, trichloroethylene, toluene, tetra-chloroethylene, ethylbenzene, m+p-xylenes, o-xylene, styrene, 1,3,5- and 1,2,4-trimethylbenzenes. Among 12 target VOCs, the most abundant compound appeared to be toluene, being followed by xylenes. The mean concentrations at the urbn site were 1.2 pub for benzene and 20.4 ppb for toluene (n=221) while the mean levels at the suburban site were 0.9 ppb and 4.3 ppb for benzene and toluene (n=96), respectively. The urban site concentrations were typically several-fold higher than those measured at the suburban site. It was found that general trends of VOC levels were significantly dependent on traffic conditions at the sampling site since VOC concentrations were at their maximum during rush hours, i.e. $9{\sim}12a.m$ and $6{\sim}9p.m$. Statistical investigations were conducted to investigate any significant relationships between VOC concentrations and affecting factors. Calculated correlation coefficients among VOCs were positively significant at a level of 0.05 in most cases. Increased concentrations of toluene in the urban site were estimated to reflect the effect of large industrial sources, mainly from textile industry.

• Earthquakes and Structures
• /
• v.2 no.4
• /
• pp.357-376
• /
• 2011

Ground motion models predict the mean and standard deviation of the logarithm of spectral acceleration, as a function of predictor variables such as earthquake magnitude, distance and site condition. Such models have been developed for a variety of seismic environments throughout the world. Some calculations, such as the Conditional Mean Spectrum calculation, use this information but additionally require knowledge of correlation coefficients between logarithmic spectral acceleration values at multiple periods. Such correlation predictions have, to date, been developed primarily from data recorded in the Western United States from active shallow crustal earthquakes. This paper describes results from a study of spectral acceleration correlations from Japanese earthquake ground motion data that includes both crustal and subduction zone earthquakes. Comparisons are made between estimated correlations for Japanese response spectral ordinates and correlation estimates developed from Western United States ground motion data. The effect of ground motion model, earthquake source mechanism, seismic zone, site conditions, and source to site distance on estimated correlations is evaluated and discussed. Confidence intervals on these correlation estimates are introduced, to aid in identifying statistically significant differences in correlations among the factors considered. Observed general trends in correlation are similar to previous studies, with the exception of correlation of spectral accelerations between orthogonal components, which is seen to be higher here than previously observed. Some differences in correlations between earthquake source zones and earthquake mechanisms are observed, and so tables of correlations coefficients for each specific case are provided.

• Journal of Wetlands Research
• /
• v.2 no.1
• /
• pp.87-94
• /
• 2000

The purpose of this study was to analysis the pollutant loading of Chin yang Reservoir according to the variation of outflow. Regression equation of the pollutant loading and outflow was represented as $L=a\;Q^b$ in which L = pollutant loading(kg/day), a and b = regression coefficient, and Q = outflow($m^3/day$). Regression coefficients ($R^2$) of Sanchung, Sinan and Changchon site was in range of 0.8376 to 0.9818. Therefore the pollutant loading was good correlated with outflow. Changchon site had minimum b value because outflow of pollutant was little compared with rainfall. The SS was the highest b value 1.621~1.7834 among water quality parameters because the pollutant loading of SS was much affected by outflow. Also, the pollutant loadings per area could be calculated and compared in case of the dry season, normal season and flood season. The pollutant loading in the normal and flood season except the dry season were higher in order of Sanchung, Sinan and Changchon site. Pollutant loading per area were higher in order of Sinan, Sanchung and Changchon site. When it compared with pollutant loading per area calculated using pollutant unit loading, T-N was much different each other.

• Journal of Industrial Technology
• /
• v.22 no.B
• /
• pp.95-101
• /
• 2002

Much of domestic city is served by combined sewer system rather than separate sanitary or storm sewers. During wet weather, when the volume of sanitary sewage and storm water entering the combined sewers exceeds the system capacity, the system is designed to overflow at several designated CSOs. The objective of this research is to have grasp of characteristics of combined sewer runoff and to evaluate efficiently the intercepted volume of CSOs. During the wet weather in first rainfall, SS load at each site H-1, H-2, and H-3 were 600kg/event, 370kg/event, and 289kg/event, SS load at each site in second rainfall were 216kg/event, 113kg/event, and 37.2kg/event. EMCs at each site were 702mg/L, 816mg/L, 861mg/L in first rainfall and 99.9mg/L, 161.9mg/L, 103.6mg/L in second rainfall, respectively. First flush coefficients b at each site were 0.237, 0.166, and 0.151.

• Journal of Korean Society for Atmospheric Environment
• /
• v.15 no.5
• /
• pp.555-566
• /
• 1999

The rainwater samples were collected from the 1100 Site of Mt. Halla and Cheju city during the period of March in 1997 to August in 1998, and the major soluble ions were analyzed. The confidence of analytical data was confirmed by using the comparison methods such as ino-balance, electric conductivity and acid fraction, all of which correlation coefficients were above 0.94. The ionic strengths lower than $10^{-4}$ M, the basis for the pure rainwater, were found in 47% and 38% at 1100 Site and Cheju city, respectively. The precipitations in Cheju city were more influenced by the oceanic effect than those in 1100 Site. The acidity contribution was mainly by $SO_4^{2-}$ and $NO_3^-$ in both areas, and the organic acids have contributed to the acidity with only 5~7%. The neutralization factors by $NH_3$ were about 46% at both 1100 site and Cheju city, whereas those by $CaCO_3$ were 11% and 15% at 1100 site and Cheju city respectively, and the free acidity were both about 35% in average. From the MSA analysis, it was found that the air in Cheju island has been influenced by the pollution from the other areas. The sources of the rainwater components in 1100 Site and Cheju city were also studied with a factor analyzing way, and the most probable factors were found to be anthropotgenic, oceanic, and soil-sourced. The results of multiple regression analysis have shown that $SO_4^{2-}$ was dissolved mostly in the form of $H_2SO_4, CaSO_4 and (NH_4)_2SO_4$, and $NO_3^-$ was in the form of $HNO_3, Ca(NO_3)_2 and NH_4NO_3$.

• Journal of Radiation Protection and Research
• /
• v.41 no.2
• /
• pp.173-178
• /
• 2016

Background: In situ gamma spectrometry has been used to measure environmental radiation, assumptions are usually made about the depth distribution of the radionuclides of interest in the soil. The main limitation of in situ gamma spectrometry lies in determining the depth distribution of radionuclides. The objective of this study is to develop a method for subsurface characterization by in situ measurement. Materials and Methods: The peak to valley method based on the ratio of counting rate between the photoelectric peak and Compton region was applied to identify the depth distribution. The peak to valley method could be applied to establish the relation between the spectrally derived coefficients (Q) with relaxation mass per unit area (${\beta}$) for various depth distribution in soil. The in situ measurement results were verified by MCNP simulation and calculated correlation equation. In order to compare the depth distributions and contamination levels in decommissioning KRR site, in situ measurement and sampling results were compared. Results and Discussion: The in situ measurement results and MCNP simulation results show a good correlation for laboratory measurement. The simulation relationship between Q and source burial for the source layers have exponential relationship for a variety depth distributions. We applied the peak to valley method to contaminated decommissioning KRR site to determine a depth distribution and initial activity without sampling. The observed results has a good correlation, relative error between in situ measurement with sampling result is around 7% for depth distribution and 4% for initial activity. Conclusion: In this study, the vertical activity distribution and initial activity of $^{137}Cs$ could be identifying directly through in situ measurement. Therefore, the peak to valley method demonstrated good potential for assessment of the residual radioactivity for site remediation in decommissioning and contaminated site.

• Journal of the Korean Society of Safety
• /
• v.33 no.2
• /
• pp.32-38
• /
• 2018

The sprinkler system is a basic fire extinguishing system widely used, but there is a lack of quantitative assessment of its performance. In this study, to evaluate the fire extinguishing performance of the sprinkler head according to the discharge coefficients, experiments were conducted. Experimental sprinkler heads were selected with heads having K50, K80 and K115 water discharge coefficients, and the fire source was assumed to be an indoor fire in Class A Model 1. As experimental results, the time required for the fire chamber to cool down to $200^{\circ}C$ was 26 seconds for the K115 head, 414 seconds for the K80 head, and 481 seconds for the K50 head, so the cooling time of the K115 head was decreased by 94.5% compared to K50 head. In the case of restoring the oxygen concentration to 15%, the K115 head did not decrease below the oxygen concentration of 15%, and the K80 head took 145 seconds and the K50 head took 484 seconds. The lowest oxygen concentration in the fire chamber was 16.1% for the K115 head, 14.33% for the K80 head, and 11.28% for the K50 head, indicating that the K115 head was superior to the K80 and K50 heads by 13.1% and 43.7%, respectively. As the experimental results show, there is big difference in the extinguishing performance depending on the discharge coefficients of the sprinkler head. Therefore, in designing the sprinkler system, the discharge coefficients of the sprinkler head should be selected considering the heat release rate at the installation site and the fire extinguishing characteristics of sprinkler head.