• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.73-84
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• 2006

The objective of this study was to analyze long-term temporal trends of water chemistry and spatial heterogeneity for 10 sampling sites of the Yeongsan River watershed using water quality dataset during 1995 to 2004 (obtained from the Ministry of Environment, Korea). The water quality, based on multi-parameters of biological oxygen demand (BOD), chemical oxygen demand (COD), conductivity, dissolved oxygen (Do), total phosphorus (TP), total nitrogen (TN) and total suspended solids (TSS), largely varied depending on the sampling sites, seasons and years. Largest seasonal variabilities in most parameters occurred during the two months of July to August and these were closely associated with large spate of summmer monsoon rain. Conductivity, used as a key indicator for a ionic dilution during rainy season, and nutrients of TN and TP had an inverse function of precipitation (absolute r values> 0.32, P< 0.01, n= 119), whereas BOD and COD had no significant relations(P> 0.05, n= 119) with rainfall. Minimum values in conductivity, TN, and TP were observed during the summer monsoon, indicating an ionic and nutrient dilution of river water by the rainwater. In contrast, major inputs of total suspended solids (TSS) occurred during the period of summer monsoon. BOD values varied with seasons and the values was closely associated (r=0.592: P< 0.01) with COD, while variations of TN were had high correlations (r=0.529 : P< 0.01) with TP. Seasonal fluctuations of DO showed that maximum values were in the cold winter season and minimum values were in the summer seasons, indicating an inverse relation with water temperature. The spatial trend analyses of TP, TN, BOD, COD and TSS, except for conductivity, showed that the values were greater in the mid-river reach than in the headwater and down-river reaches. Conductivity was greater in the down-river sites than any other sites. Overall data of BOD, COD, and nutrients (TN, TP) showed that water quality was worst in the Site 4, compared to those of others sites. This was due to continuous effluents from the wastewater treatment plants within the urban area of Gwangju city. Based on the overall dataset, efficient water quality management is required in the urban area for better water quality.

• Water for future
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• v.28 no.6
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• pp.147-158
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• 1995

The purpose of this study is to establish a method of estimating the daily urban water demand using statistical model. This method will be used for the development of the efficient management and operation of the water supply facilities. The data used were the daily urban water use, the population, the year lapse and the weather conditions such as temperature, precipitation, relative humidity, etc. Kwangju city was selected for the case study area. The raw data used in this study were rearranged either by month or by season for the purpose of analysis, and the statistical analysis was applied to the data to obtain the regression model. As a result, the multiple linear regression model was developed to estimate the daily urban water use based on the seather condition. The regression constant and the model coefficients were determined for each month of a year. The accuracy of the model was within 3% of average error and within 10% of maximum error. The developed model was found to be useful to the practical operation and management of the water supply facilities.

• Economic and Environmental Geology
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• v.51 no.2
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• pp.185-201
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• 2018

Nuclear power plants(NPP) are constructed and operated to ensure safety against natural disasters and man-made disasters in all processes including site selection, site survey, design, construction, and operation. This paper will introduce a series of efforts conducted in Korea Hydro and Nuclear Power Co. Ltd., to assure the safety of nuclear power plant against earthquakes and other natural hazards. In particular, the present status of the earthquake, fault, and slope safety monitoring system for nuclear power plants is introduced. A earthquake observatory network for the NPP sites has been built up for nuclear safety and providing adequate seismic design standards for NPP sites by monitoring seismicity in and around NPPs since 1999. The Eupcheon Fault Monitoring System, composed of a strainmeter, seismometer, creepmeter, Global Positioning System, and groundwater meter, was installed to assess the safety of the Wolsung Nuclear Power Plant against earthquakes by monitoring the short- and long-term behavioral characteristics of the Eupcheon fault. Through the analysis of measured data, it was verified that the Eupcheon fault is a relatively stable fault that is not affected by earthquakes occurring around the southeastern part of the Korean peninsula. In addition, it was confirmed that the fault monitoring system could be very useful for seismic safety analysis and earthquake prediction study on the fault. K-SLOPE System for systematic slope monitoring was successfully developed for monitoring of the slope at nuclear power plants. Several kinds of monitoring devices including an inclinometer, tiltmeter, tension-wire, and precipitation gauge were installed on the NPP slope. A macro deformation analysis using terrestrial LiDAR (Light Detection And Ranging) was performed for overall slope deformation evaluation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.4
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• pp.224-236
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• 2002

A long-term growth simulation was performed at 496 land units in the western coastal plains (WCP) of North Korea to test the potential adaptability of each land unit for growing South Korean rice cultivars. The land units for rice cultivation (CZU), each of them represented by a geographically referenced 5 by 5 km grid tell, were identified by analyzing satellite remote sensing data. Surfaces of monthly climatic normals for daily maximum and minimum temperature, precipitation number of rain days and solar radiation were generated at a 1 by 1 km interval by spatial statistical methods using observed data at 51 synoptic weather stations in North and South Korea during 1981-2000. Grid cells felling within a same CZU and, at the same time, corresponding to the satellite data- identified rice growing pixels were extracted and aggregated to make a spatially explicit climatic normals relevant to the rice growing area of the CZU. Daily weather dataset for 30 years was randomly generated from the monthly climatic normals of each CZU. Growth and development parameters of CERES-rice model suitable for 11 major South Korean cultivars were derived from long-term field observations. Eight treatments comprised of 2 transplanting dates $\times$ 2 cropping systems $\times$ 2 irrigation methods were assigned to each cultivar. Each treatment was simulated with the randomly generated 30 years' daily weather data (from planting to physiological maturity) for 496 land units in WCP to simulate the growth and yield responses to the interannual climate variation. The same model was run with the input data from the 3 major crop experiment stations in South Korea to obtain a 30 year normal performance of each cultivar, which was used as a "reference" for comparison. Results were analyzed with respect to spatial and temporal variation in yield and maturity, and used to evaluate the suitability of each land unit for growing a specific South Korean cultivar. The results may be utilized as decision aids for agrotechnology transfer to North Korea, for example, germplasm evaluation, resource allocation and crop calendar preparation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.3
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• pp.188-194
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• 2007

The relationships between pine mushroom emergence and meteorological factors were analyzed with three years (from 2003 to 2005) of measurement data at Yangyang site, in order to evaluate the effect of micrometeorological environment on pine mushroom production. fine mushroom was daily monitored and collected in the survey area during the its producing period (approximately one month). Pine mushroom production was highest in 2005 with the meteorological conditions of high temperature and frequent rainfalls in October. The production was lowest in 2004 due to dry conditions from mid September to late October, The meterological factors related to humidity (i.e., relative humidity, soil water content, and precipitation) were better correlated than those related to temperature (i.e., air and soil temperature, soil heat flux and solar radiation) with pine mushroom production. However, all of the correlation coefficients were statistically insignificant with values ranging from 0.15 to 0.46. Such poor correlations may be attributed to various other environmental conditions (e.g., topography, soil, vegetation, other fungi, the relationship between pine mushroom and pine forest) affecting pine mushroom production. We found that a mycelium requires a stimulation of low temperature (of three-day moving average) below $19.5^{\circ}C$, in order to farm a mushroom primordium which grows to pine mushroom after 16 days from the stimulation. We also found that the pine mushroom production ended when the soil temperature (of three-day moving average) fell below $14.0^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.2
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• pp.252-263
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• 1997

Temperature and salinity were observed in Kugum Suro Channel in February, April, August and October 1993. Temperature ranged from $7.0^{\circ}C\;to\;25.0^{\circ}C$ throughout the year and its variation was about $18^{\circ}C$. The maximum temperature difference between surface and bottom was less than $0.75^{\circ}C$ for a year, which meant that the temperature stratification in Kugum Suro Channel was considerably week. Salinity had also a small variation range of less than $0.5\%_{\circ}$. Salinity varied from $34.0\%_{\circ}$ in April to $30.0\%_{\circ}$ in August and its fluctuation patterns were quite similar to the seasonal variations of the precipitation and the duration of sunshine observed at Kohung Weather station. Seasonal variation of sea water density in T-S diagram showed that the water mass in Kugum Suro Channel could be largely affected by regional atmospheric conditions. Temperature increased in ebb tide and decreased in flood tide, but salinity decreased in ebb tide and increased in flood tide for a day. The period of fluctuations in temperature and salinity measured for 25 hours was nearly coincident with the semi-diurnal tide which was predominant in that region. Stratification parameters computed in Kugum Suro Channel areas were less than $4.0J/m^3$ the year round, which indicated that vortical mixing from the bottom boundary caused by tidal current played an important role in deciding the stratification regime in Kugum Suro Channel. In estimating the equation which defines stratification and mixing effects in the observed areas, the tidal mixing term ranged from $4.7J/M^3\;to\;14.1J/m^3$ was greater than any other terms like solar radiation, river discharge and wind mixing.

• Journal of Korean Society of Forest Science
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• v.39 no.1
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• pp.1-34
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• 1978

On July 8, 1977, 432mm of precipitation which is the largest daily storm in Korea fell on the city of Anyang where a nearby suburban community of Seoul. Average storm intensities of 90mm per hour were recorded during the period from 1900~2200 hours on this date. Area of landslides triggered by this storm is about 96 hectares resulting from 1,876 places within about 12,600 hectares of the watershed studied. These hazards injured hundreds of human lives and took 122 human lives. Rail and highway systems were disrupted and about 30 hectares of rice paddies were washed away and hundreds of hectares were inundated. About 500 houses were destroyed. The objectives of this study are (a) to describe the problem areas, identifying critical factors causing the landslide hazards including earth and stone-debris avalanches, (b) suggest measures which might enhance the effectiveness of stabilization measures, and (c) also suggest the landslide and flood damage prevention methods from the point view of the upper-watershed conservation techniques in Anyang hollow-basin.

• Korean journal of applied entomology
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• v.51 no.2
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• pp.99-109
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• 2012

Seasonal fluctuations of Riptortus pedestris were investigated in four regions including two sites each at Mt. Yangseong (Munui-myeon, Cheongwon-gun), O-chang (Cheongwon-gun), and Jujung-dong (Cheongju) using aggression pheromone traps from April to November in 2010 and 2011. Aggression pheromone and aggression pheromone + soybean traps were set at all investigated sites, and the Mt. Yangseong A and B sites were investigated at a farmland (80 m, asl) and forest (200 and 300 m). The population density of R. pedestris was high in mid June, mid August, and late October in 2010 and in early May, mid June, mid September, and early October in 2011 with trivoltine. O-chang and Jujung-dong populations, which were distinguished in farmlands and forests, were highest from June to August in the farmland and in September in the forest. Similar numbers of R. pedestris were capture in the farmlands and the forest in June-August, September-November, respectively. From the results of the four regions, more R. pedestris adults were captured in the aggression pheromone + soybean trap than that in the pheromone trap. To investigate the migration route by altitude, 500 R. pedestris adults marked with fluorescent paint were released and re-caught insects were counted in traps after 10 and 20 days. The pattern of the re-caught R. pedestris indicated migration from the forest to farmlands during April-June. These results suggest that the insects did not migrate in August because food was plentiful in the forest at 200 m, but they moved to the forest during October due to the scarcity of food and for overwintering. The R. pedestris seasonal fluctuations in 2011 were affected heavily by the environment, particularly rain precipitation.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.197-208
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• 2020

This study was carried out to analyze spatial and temporal incidence characteristics of scrub typhus and predict the future incidence of scrub typhus since the incidences of scrub typhus have been rapidly increased among vector-borne diseases. A maximum entropy (MaxEnt) ecological model was implemented to predict spatial distribution and incidence rate of scrub typhus using spatial data sets on environmental and social variables. Additionally, relationships between the incidence of scrub typhus and critical spatial data were analyzed. Elevation and temperature were analyzed as dominant spatial factors which influenced the growth environment of Leptotrombidium scutellare (L. scutellare) which is the primary vector of scrub typhus. A temporal number of diseases by scrub typhus was predicted by a deep neural network (DNN). The model considered the time-lagged effect of scrub typhus. The DNN-based prediction model showed that temperature, precipitation, and humidity in summer had significant influence factors on the activity of L. scutellare and the number of diseases at fall. Moreover, the DNN-based prediction model had superior performance compared to a conventional statistical prediction model. Finally, the spatial and temporal models were used under climate change scenario. The future characteristics of scrub typhus showed that the maximum incidence rate would increase by 8%, areas of the high potential of incidence rate would increase by 9%, and disease occurrence duration would expand by 2 months. The results would contribute to the disease management and prediction for the health of residents in terms of public health.

• Journal of Korean Society of Forest Science
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• v.80 no.3
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• pp.279-286
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• 1991

This study was carried out to investigate relationships between atmospheric $SO_2$ concentration and both soluble sulphur contents in the tree leaves and bark pH to test the possibility of using them as bioindicators for air pollution. Mt. Kwanak, Mt. Nam, Mt. Bukhan (located in Seoul) and Mt. Paldal (located in Suwon, Kyonggi-do) as polluted areas and Pyongchang, Kwangwon-do as an unpolluted area were selected for this study. Soluble sulphur contents in the leaves and hark pH of two tree species (Pines densiflora S. et Z. and Quercus mongolica Fisch.) were analyzed in May, August, and October, 1990 by $BaSO_4$ precipitation method and pH measurement, respectively. In both species, concentration of soluble sulphur in the leaves increased with increasing concentration of atmospheric $SO_2$ (correlation coefficient : 0.52). Soluble sulphur contents in the 2-year-old needles of Pines densiflora (0.170%) and current year leaves of Quercus mongolica (0.081%) in Mt. Nam in the center of Seoul were higher than those in unpolluted Pyongchang area (0.023% and 0.034%, respectively). Bark pH decreased with increasing atmospheric $SO_2$ concentration (correlation coefficient : -0.52). Bark pH of P. densiflora (pH 3.42) and Q. mongolica (pH 3.63) in Mt. Nam were lower than those in Pyongchang area (pH 3.94 and pH 4.93, respectively). Both soluble S content in the leaves and bark pH were recognized as suitable bioindicators for air pollution by $SO_2$. Especially, bark pH showed more sensitive response to air pollution by $SO_2$ than soluble S concentration in the leaves. The lowest concentration of soluble sulphur and the highest bark pH in August were considered to be due to heavy rain during the rainy season. Soluble S content in the leaves and bark pH were not significantly different at 5% level between the two species in polluted areas.