• Parasites, Hosts and Diseases
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• v.54 no.5
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• pp.591-603
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• 2016

Investigations of Enterobius sp. infection in prehistory have produced a body of data that can be used to evaluate the geographic distribution of infection through time in the Americas. Regional variations in prevalence are evident. In North America, 119 pinworm positive samples were found in 1,112 samples from 28 sites with a prevalence of 10.7%. Almost all of the positive samples came from agricultural sites. From Brazil, 0 pinworm positive samples were found in 325 samples from 7 sites. For the Andes region, 22 pinworm positive samples were found in 411 samples from 26 sites for a prevalence of 5.3%. Detailed analyses of these data defined several trends. First, preagricultural sites less frequently show evidence of infection compared to agricultural populations. This is especially clear in the data from North America, but is also evident in the data from South America. Second, there is an apparent relationship between the commonality of pinworms in coprolites and the manner of constructing villages. These analyses show that ancient parasitism has substantial value in documenting the range of human behaviors that influence parasitic infections.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.2
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• pp.68-79
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• 2014

This paper analyzes the characteristics of trip chaining activities of elderly and explores temporal and spatial distribution. The research also estimates ordered probit model and binary logistic model to investigate various factors affecting trip chaining and mode choice patterns. We utilized household survey data for elderly conducted in 2006 and 2010 in Seoul metropolitan area. Research results indicate that trip chaining showed an increasing trend and simple trip chaining counts for more than 85%. GIS mapping expressed spatial distribution of trip departure and arrival areas, particularly showing regional changes in job-related trips. We also found that more factors influence trip chaining in 2010, compared with 2006, and travel cost is more sensitive than travel time in determining travel mode. The research contributes to establish transportation policies based on travel behavior of elderly in a upcoming super-aged society.

• Journal of the Korean association of regional geographers
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• v.17 no.2
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• pp.204-215
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• 2011

One of the major concerns to improve social-wellbeing is uneven spatial distribution of public service. The paper analyses the changes in the geographic distribution of public service facilities over time. The analysis is with a case study about JeollaNamdo Province including Gwangju Metropolitan City, 1985~2005. It employed eighteen proxies in different fields to measure public service and utilized cluster analyses, and various summary statistics including Schutz's coefficient and regression. The results show that overall social well-being has improved during the two decades and the gap between Gwanju City and the major cities in the JeollaNamdo Province has narrowed. However, the disparity between mainland and island areas still persists, calling our attention to the island areas.

• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.245-253
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• 1995

We have analyzed the time series of Ca II H,K and ${\lambda}8498$ line profiles taken for a sunspot (SPO 5007) with the Echelle spectrograph attached to Vacuum Tower Telescope at Sacramento Peak Solar Observatory. Each set of spectra was taken simultaneously for 20 minutes at a time interval of 30 seconds. A total of 40 photographic films for each line was scanned by a PDS at Korea Astronomy Observatory. The central peak intensity of Ca II H ($I_{max}$), the intensity measured at ${\Delta}{\lambda}=-0.1{\AA}$ from the line center of ${\lambda}8498(I_{{\lambda}8489})$, the radial velocity ($V_r$) and the Doppler width (${\Delta}{\lambda}_D$) estimated from Ca II H have been measured to study the dynamical behaviors of the sunspot chromosphere. Fourier analysis has been carried out for these measured quantities. Our main results are as follows: (1) We have confirmed the 3-minute oscillation being dominant throughout the umbra. The period of oscillations jumps from 180 sec in the umbra to 500 to 1000 sec in the penumbra. (2) The nonlinear character of the umbral oscillation is noted from the observed sawtooth shaped radial velocity fluctuations with amplitudes reaching up to $5{\sim}6\;km/sec$. (3) The spatial distribution of the maximum powers shows that the power of oscillations is stronger in the umbra than in the penumbra. (4) The spatial distributions of the time averaged < $I_{max}$ > and < $V_r$ > across the spot are found to be nearly axially symmetric, implying that the physical quantities derived from the line profiles of Ca II H and ${\lambda}8498$ are inherently associated with the geometry of the magnetic field distribution of the spot. (5) The central peaks of the CaII H emission core lead the upward motions of the umbral atmosphere by $90^{\circ}$, while no phase delay is found in intensities between $I_{max}$ and $I_{{\lambda}8498}$, suggesting that the umbral oscillation is of standing waves.

• Journal of Korea Water Resources Association
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• v.56 no.11
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• pp.705-720
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• 2023

In South Korea, ongoing incidents related to drinking water quality have eroded consumer trust. Specifically, beyond quality incidents, there have been complaints about taste, odor, and other issues stemming from the presence of chlorine. To address this, water service operators are employing various management strategies from both temporal (scheduling) and spatial (rechlorination) perspectives to ensure uniform and safe distribution of chlorine residuals. In this study, we focus on the optimal monthly management of chlorine residuals, based on water distribution network analysis. Water quality reaction coefficients, including bulk fluid and wall reaction coefficients, were estimated through lab-scale tests and EPANET water quality simulations, respectively, accounting for temperature variations in a large-scale water distribution network. Utilizing these estimated coefficients, we examined the monthly variations in chlorine residual distribution under different chlorine injection conditions. The results indicate that the efficient concentration for chlorine injection, which satisfies the residual chlorine limit range, varies with temperature changes. Consequently, it is imperative to establish a specific and quantitative chlorine injection plan that considers the accurate spatial distribution of monthly chlorine residuals.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.4
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• pp.234-243
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• 2022

In Korea, hail damage occurs every year, and in the case of agriculture, it causes severe field crop and cultivation facility losses. Therefore, it is necessary to develop a hail information service system customized for Korea's primary production and crop-growing areas to minimize hail damage. However, the observation of hail is relatively more difficult than that of other meteorological variables, and the available data are also spatially and temporally variable. A hail information service system was developed to understand the temporal and spatial distribution of hail occurrence. As part of this, a hail observation database was established that integrated the observation data from Korea Meteorological Administration with the information from newspaper reports. Furthermore, a hail risk map was produced based on this database. The risk map presented the nationwide distribution and characteristics of hail showers from 1970 to 2018, and the northeastern region of South Korea was found to be relatively dangerous. Overall, hail occurred nationwide, especially in the northeast and some inland areas (Gangwon, Gyeongbuk, and Chungbuk province) and in winter, mainly on the north coast and some inland areas as graupel (small and soft hail). Analyzing the time of day, frequency, and hailstone size of hail shower occurrences by region revealed that the incidence of large hail stones (e.g., 10 cm at Damyang-gun) has increased in recent years and that showers occurred mainly in the afternoon when the updraft was well formed. By integrating multidisciplinary data, the temporal and spatial gap in hail data could be supplemented. The hail risk map produced in this study will be helpful for the selection of suitable crops and growth management strategies under the changing climate conditions.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.3
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• pp.151-164
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• 2013

Multidimensional dynamic water quality model of organic matter and trophic state was applied to the Han River system. The model was calibrated using field measurement data obtained during the year of 2007. The model results showed reasonable performance in predicting temporal variations of TN, TP, Chl-a and BOD concentrations. The applied integrated modeling system can be effectively used to simulate water quality as well as hydrodynamic and water temperature for river-lake continuous system in the Han River. Utilizing the calibrated model, we analyzed the spatial and temporal distributions of TN, TP, Chl-a and BOD concentrations in the Han River system. The temporal variations of water quality at each river reach and lake were effectively simulated with the developed model and spatial distribution of water qualities in the Han River system could be compared. The multidimensional dynamic modeling system can simulate the water qualities of entire waterbody where Lake Paldang and the incoming flows are included using single modeling system. So it can be effectively used for integrated water quality management of the Han River system.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.1
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• pp.1-7
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• 2014

Butyltin compounds (BTs) were determined in surface sediment samples from Ulsan Bay in 2009 and 2011, to assess the contamination status and the effectiveness of tributylin (TBT) restriction of Korea. Dibutyltin and TBT concentrations in sediments in 2011 ranged from 19.5 to 980 and 14.2 to 1204 ng Sn $g^{-1}$ dry weight, respectively. The highest TBT concentration was found in a big shipyard complex and the next highest was found in harbor, suggesting that harbor and shipyard activities are a major contamination source of TBT in Ulsan Bay. Concentrations of BTs in Ulsan Bay sediments were significantly lower in 2009 and 2011 than that in 2003 survey previously reported, probably as a consequence of the legislative action in Korea. However, TBT concentrations in sediments still exceeded ecotoxicological values. Therefore, it will be important to monitor and reduce TBT contamination in sediments until the levels fall well below ecotoxicological levels.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.1035-1039
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• 2010

For 65 national forest areas in 1993 to 2008, the ambient sulfur dioxide ($SO_2$) concentrations were measured monthly using passive samplers and compared to the those of urban areas in order to investigate the characteristics of temporal and spatial distribution. In the forest areas, annual average concentration of sulfur dioxide gradually decreased from the beginning year of monitoring to 1997 and then had no significant change, such as the annual trend in urban areas monitored by Ministry of Environment. For the monitoring term, average concentration of sulfur dioxide in the forest areas was 5.6ppb, which was lower than the 10.1ppb in the urban areas and the EC ecological standard level (7.6 ppb). Seasonally, both in forest areas and urban areas the monthly average concentrations were much higher in winter and spring due to much more heating fuel consumption, and lowest in summer. Regional comparison to other regions of Gyeongbuk and Gyeonggi province showed that the concentration of sulfur dioxide was the highest during year. A significant positive correlation between sulfur oxides' emissions and sulfur dioxide concentration by province was observed, reflecting that the size and proximity of sources of atmospheric sulfur oxides could be important factors in determination.

• 한국해양학회지
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• v.23 no.3
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• pp.130-145
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• 1988

Spatial distribution and temporal variations of phytoplankton population were investigated in Ch$\check{o}$nsu Bay, the Korean western coast. Diurnal fluctuations of phytoplankton standing crop are associated with semidiurnal tidal cycle, as high concentration at low tide and low at high tide. In monthly variations of phytopolankton standing crop, the 1st peak occurrs in March and the 2nd one in August. The study area could be divided into two parts, outer bay and inner bay according to the physical and biological factors such as water temperature and salinity, and phytoplankton distribution patterns. The northern waters of the bay, however, may be affected by irregular fresh water influx through the lock of the dike. Because of the hydrographical differences among the surveyed stations, phytoplankton species succession patterns of each station have some differences. On the whole in this study area, Paralia sulcata and Skeletonema costatum are dominant species all the year round. However, except June, Paralia sulcata, a tychopelagic diatom is not dominant species at Station 6 (northern end of the bay). This seems to be caused by the fact that the waters of northern part of the bay is less turbulent than that of the outer bay. The result of principal component analysis (PCA) indicates that Ch$\check{o}$nsu Bay is normal coastal ecosystem where the environmental conditions are cycled in a year, and water temperature and nitrogenous nutrients such as nitrate, nitrite and ammonia are major factors to influence the annual cycle of environmental conditions.