• The Journal of Engineering Geology
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• v.8 no.3
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• pp.247-259
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• 1998

Groundwater quality of the natural mineral water was investigated in hydrochemical aspects in order to ensure that mineral water meets stringent health standards. There exist 20 mineral water plants in the Daebo granite and 4 mineral water plants in the Bulguksa granite, respectively. Both granite areas show some differences in water chemistry. The pH, EC, hardness, total ionic contents in groundwater of the Daebo granite area are higher relative to those of the Bulguksa granite area. The content of major cations is in the order of Ca>Na>Mg>K, while that of major anions shows the order of $HCO_3>SO_4$>Cl>F. The fact that the $Ca-Na-HCO_3$ type is most predominant among water types may reflect that the dissolution of plagioclase that is most abundant in granitic rocks plays a most important role in groundwater chemistry. Representative correlation coefficients between chemical species are variable depending on geology. In the Daebo granite area, $Ca-HCO_3(0.84),{\;}Mg-HCO_3(0.81),{\;}SiO_2-Cl(0.74),{\;}Na-HCO_3(0.70)$ show relatively good correlationships. In the Bulguksa granite area, fairly good correlationships are found among some components such as K-Mg(0.93), $K-HCO_3(0.92)$, Mg-Cl(0.92), $Cl-HCO_3(0.91)$, and K-F(0.90). According to saturation index, most chemical species are undersaturated with respect to major minerals, except for some silica phases. Groundwater is slightly undersaturated with respect to calcite, whereas it is still greatly undersaturated with respect to dolomite, gypsum and fluorite. Based on the phase equilibrium it is clear that groundwater is mostly in equilibrium with kaolinite and becomes undersaturated with respect to feldspars, evolved from the stability area of gibbsite during water-rock interaction. While the activity of silica increases, there is no remarkable increase in the acivities of alkali ions and pH, which indicates that some amounts of silicic acid dissolved from silica phases as well as feldspars were provided to groundwater. It is concluded that chemical evolution of groundwater in granite aquifers may continue to proceed with increasing pH.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.1
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• pp.40-50
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• 2011

We study the characteristic and total flux of non-point pollutants such as total suspended solids (TSS), chemical oxygen demand (COD), dissolved nutrients, total phosphorus (TP) and total nitrogen (TN) in the storm water runoff from urban streams and sewer outlets of Banweol Industrial Complex around Shihwa Lake. The concentrations of non-point pollutants were generally increased with increasing of the duration and intensity of rainfall. Mean TSS concentration of Ansan stream was higher than that of sewer outlets but mean concentrations of COD, TP and TN were approximately 2~5 times higher of sewer outlet than of urban stream. TSS showed statistically positive relationships with COD and TP but it had negative correlation with dissolved nutrients. There was a significant correlation between total flux of non-point pollutants in the storm water runoff and total basin area of each sewer outlet, showing that the highest runoff flux was observed at 3rd sewer outlet which represents the largest basin area from Banweol industrial complex. Total runoff fluxes for TSS, COD, TP and TN in this study were 187,536 kg, 17,118 kg, 922 kg, 13,519 kg, respectively. Given the basin area of sewer outlet in Banweol industrial complex which corresponds only 3% from total catchment area around Shihwa Lake, enormous amount of non-point pollutants will be entered into Shihwa Lake without any treatment. It is necessary to manage and reduce of various non-point sources and pollutants because the runoff of nonpoint pollutants during storm events should be deteriorating the water quality of Shihwa Lake. Our results provides useful informations on the development of best managements practices (BMPs) for effective implementation of total pollution loads management system of Shihwa Lake.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.283-288
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• 2013

To evaluate the ability of the submerged plant, Ceratophyllum demersum's (C. demersum) to remove nutrients and to inhibit growth of cyanobacteria, a total of 6 mesocosms were conducted in a batch reactor for 9 days. From the 84 hr of the experiment, C. demersum was stabilized and showed daily cycle trends according to changes in pH and DO levels. The concentration of nutrients, $NH_3{^+}$, $NO_3{^-}$ and $PO_4{^3}$ continuously decreased until 9 days of the experiment, with the rapid decrease in nutrient concentration for the first 24 hours. High correlation coefficient ($r^2{\geq}0.96$, p<0.001) between the amount of C. demersum's biomass per unit area and the nutrients removal level were derived, and greater C. demersum's biomass per unit area showed higher removal efficiency of nutrients. However, there were differences in the C. demersum's activity level between batch reactors with higher and similar density of the C. demersum, but nonetheless water purification effect appears to have a significant influence due to attached algae and microorganisms. The growth rate of harmful cyanobacteria, Microcystis aeruginosa (M. aeruginosa) with C. demersum's density of 2,500 g $fw/m^2$ (100% of cover degree) was 0.31 /day, compared to the growth rate of 0.47 /day for the control group (0% of cover degree). In terms of number of cells, the control group had 1.7 times higher number of cells than the experimental group, proving that C. demersum has the ability to inhibit the growth of harmful cyanobacteria.

• Asian Journal of Turfgrass Science
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• v.22 no.1
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• pp.1-12
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• 2008

Remote sensing using multispectral radiometry may be a useful tool to detect drought stress in turf. The objective of this research was to investigate the correlation between drought stress and multispectral reflectance (MSR) from the turf canopy. St. Augustinegrass (Stenotaphrum secundatum[Walt.] Kuntze.) cultivars 'Floratam' and 'Palmetto', 'SeaIsle 1' seashore paspalum Paspalum vaginatum Swartz.), 'Empire' zoysiagrass (Zoysia japonica Steud.), and 'Pensacola' bahiagrass (Paspalum notatumFlugge) were established in lysimeters in the University of Florida Envirotron greenhouse facility in Gainesville. Irrigation was applied at 100%, 80%, 60%, or 40% of evapotranspiration (ET). Weekly evaluations included: a) shoot quality, leaf rolling, leaf firing b) soil moisture, chlorophyll content index; c) photosynthesis and d) multispectral reflectance. All the measurements were correlated with MSR data. Drought stress affected the infrared spectral region more than the visible spectral region. Reflectance sensitivity to water content of leaves was higher in the infrared spectral region than in the visible spectral region. Grasses irrigated at 100% and 80% of ET had no differences in normalized difference vegetation indices (NDVI), leaf area index (LAI), and stress indices. Grasses irrigated at 60% and 40% of ET had differences in NDVI, LAI, and stress indices. All measured wavelengths except 710nm were highly correlated (P < 0.0001) with turf visual quality, leaf firing, leaf rolling, soil moisture, chlorophyll content index, and photosynthesis. MSR could detect drought stress from the turf canopy.

• Food Engineering Progress
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• v.21 no.2
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• pp.132-137
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• 2017

The purpose of this study was to optimize dough properties using response surface methodology (RSM) and to demonstrate the performances of dough prepared under optimized conditions. Dough mixed with yeast, margarine, salt, sugar and wheat flour was prepared by fermentation process. Hardness, cohesiveness and springiness of dough were selected as critical quality attributes. The critical formulations (yeast and water) and process (fermentation time) variables were selected as critical input variables based on preliminary experiment. Box-Behnken design (BBD) was used as RSM. As a result, the quardratic, the squared and the linear model respectively provided the most appropriate fit ($R^2$>90) and had no significant lack of fit (p>0.05) on critical quality attributes (hardness, cohesiveness and springiness). The accurate prediction of dough characteristics was possible from the selected models. It was confirmed by validation that a good correlation was obtained between the actual and predicted values. In conclusion, the methodologies using RSM in this study might be applicable to the optimization of fermented foods containing various wheat flour and yeast.

• Horticultural Science & Technology
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• v.16 no.1
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• pp.37-39
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• 1998

This study was carried out to investigate the effects of nutrient solution concentration, irrigation frequency on growth, flowering, and cut flower longevity of Dendranthema grandiflorum (Ramat.) Kitamura 'Shuhouno-chikara' hydroponically grown in perlite media. Not only stem length but also mineral contents of each plant organ in nutrient solution culture were much higher than those in soil culture. 1/2S of nutrient solution was good at early stage, but 1S of nutrient solution was better as chrysanthemum growth progressed. Among different concentrations of nutrient solution, mineral contents of each plant part showed no significant difference. 1S treatment of nutrient solution increased the vase life by 3 days than 2S treatment. The growth and mineral contents of each plant organ were great in plants irrigated 8 times a day, because of high moisture contents of medium and high water availability, followed by more frequent nutrient replenishment near roots. There was no correlation between nutrient solution concentration and vase life of cut flower grown in nutrient solution culture. Cut flowers irrigated twice per day had the longer vase life than other treatments (4, 8 times).

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.4
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• pp.57-67
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• 2014

The vigor condition of trees is an important indicator for the management of urban forested area. But difficulties in how to assess the tree vigor condition still remain. Previous efforts were limited in the 1) measurement of single indicator rather than using multiple indices, 2) purpose-oriented measurement such as for air-pollution effect or specific pathological symptom, and 3) ordinal-scale evaluations by field crews 4) despite human errors based on his/her experiences or prior knowledge. Therefore, this study attempted to develop a quantitative and objective methodology for assessing tree vigor condition, by measuring multiple modules and building the profile inventory. Furthermore, the possibility and limitations were discussed in terms of schematic frames describing tree vigor condition. The vigor condition of 56 flowering cherry plants in urban park were assessed by in-situ measurements of following eight items; growth of crown(Gc), growth of shoots, individual tree volume(Vol), plant area index, woody area index, leaf area index, leaf chlorophyll content(Lc) and leaf water content(Lw). For validation, these measurements were compared with the ranks of holistic tree vigor condition, which were visually assessed using a 4-point grading scale based on the expert's knowledge. As a result, the measures of each evaluation item successfully highlighted a variety of aspects in tree vigor condition, including the states of both photosynthetic and non-photosynthetic parts. The variation in the results depending on evaluated parts was shown within an individual tree, even though the broad agreement among the results was found. The result of correlation analysis between the tested measurements and 4-point visual assessment, demonstrated that the state of water-stressed foliage of the season (Lw) or the development of plant materials since sapling phase (Vol) could be better viewed from the outer appearance of trees than other symptoms. But only based on the visual assessment, it may be difficult to detect the quality of photosynthesis (Lc) or the recent trend in growth of trees (Gc). To make this methodology simplified for the broad-scale application, the tested eight measurements could be integrated into two components by principal component analysis, which was labelled with 'the amount of plant materials' and 'vigor trend', respectively. In addition, the use of these quantitative and multi-scale indicators underlies the importance of assessing various aspects of tree vigor condition, taking into account the response(s) on different time and spatial scale of pressure(s) shown in each evaluated module. Future study should be advanced for various species at diverse developing stages and environment, and the application to wide areas at a periodic manner.

• Journal of Korea Water Resources Association
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• v.55 no.9
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• pp.679-686
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• 2022

As the occurrences of flash floods have increased due to climate change, faster and more accurate precipitation observation using X-band radar has become important. Therefore, the Ministry of Environment installed two dual-pol X-band radars at Samcheok and Uljin. The radar data used in this study were obtained from two different elevation angles and composed to reduce the shielding effect. To obtain quantitative rainfall, quality control (QC), K_DP retrieval, and Hybrid Surface Rainfall (HSR) methods were sequentially applied. To improve the accuracy of the quantitative precipitation estimation (QPE) of the X-band radar, we retrieved parameters for the relationship between rainfall rate and specific differential phase, which is commonly called the R-K_DP relationship; hence, an empirical approach was developed using multiple rain gauges for those two radars. The newly suggested relationship, R = 27.4K^0.81_DP, slightly increased the correlation coefficient by 1% more than the relationship suggested by the previous study. The root mean square error significantly decreased from 3.88 mm/hr to 3.68 mm/hr, and the bias of the estimated precipitation also decreased from -1.72 mm/hr to -0.92 mm/hr for overall cases, showing the improvement of the new method.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.151-151
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• 2023

본 연구는 호우(heavy rain) 발생 시 대기 중 미세먼지(particulate matter, PM) 저감효과를 규명하고 강우 지속에 따른 빗물 수질(pH, 전기전도도(electrical conductivity, EC), 수용성 이온) 분석을 통해 대기 중 PM이 빗물 수질에 미치는 영향을 평가하였다. 2020년 3월부터 2021년 2월까지강우 강도(7.5 mm/h)를 기준으로 총 6회의 강우를 대상으로 하였으며 빗물 샘플은 집수장치를 통해 50 mL를 연속적으로 수집하여 수질을 분석하였다. 대기 중 PM_2.5 (≤ 2.5 ㎛ in diameter) 및 PM₁₀ (≤ 10 ㎛ in diameter) 농도는 기상청 내 부산 남구 대연동 관측소의 automatic weather system (AWS)에서 측정된 일평균 자료를 이용하였다. 강우에 따른 대기 중 PM의 저감효율은 상대적으로 PM₁₀에서 뚜렷하게 나타났으며, 특히 강우 강도 7.5 mm/h 이상(유형 1)의 호우 발생 시60% 이상의 저감효율을 보였다. 반면, 강우 강도 7.5 mm/h 이하(유형 2)일 때는 10% 이하의 저감효율을 보였으며, 강우 지속에 따라 대기 중 PM₁₀ 농도가 증가하는 경향을 보이기도 하였다. 총108개의 빗물 샘플 수질을 분석한 결과, 유형 1의 경우 초기 빗물의 평균 EC는 58.5 µS/cm으로 상대적으로 높았으며 대기 중 PM₁₀과 양의 상관관계(r = 0.99)를 보였고 평균 pH는 4.3으로 산성도가 높게 나타났으며 대기 중 PM₁₀과 음의 상관관계(r = -0.99)를 보였다. 반면, 유형 2의 경우 대기 중 PM₁₀과 EC (r = -0.56) 및 pH (r = -0.41) 간 뚜렷한 상관관계가 나타나지 않았다. 또한 강우가 지속됨에 따라 EC와 수용성 양이온(Na⁺, Mg²⁺, K⁺, Ca²⁺, NH₄⁺) 및 음이온(Cl^-, NO₃^-, SO₄^2-)의 농도는 지속적으로 감소하는 경향을 보였으나 pH의 경우 강우 강도에 따라 증감의 경향이 다르게 나타났다. 유형 1의 경우 강우 지속에 따라 pH가 증가하여 산성도가 낮아졌으나 유형 2는 pH의 증감 형태를 뚜렷하게 확인하기 어려웠다. 연구 결과를 통해 강우 초기 높은 강도로 강우가 지속될 경우 대기 중 PM₁₀이 빗물 수질에 영향을 미칠 수 있는 것으로 판단되며, 이에 따라 호우 발생 시 강우가 대기 중 오염물질을 지표면으로 유입시킬 수 있는 매개체로 작용할 수 있음을 지시한다.

• Korean Journal of Ecology and Environment
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• v.44 no.4
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• pp.396-406
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• 2011

To analyze between water quality and community structure of benthic macroinvertebrates, we selected four reservoirs (Lake Sayeon, Lake Daeam, Seonam reservoir and Lake Hoeya) in Ulsan-si and studied them from February 2010 to October 2010. The annual mean BOD (Biochemical Oxygen Demand) in the four lakes was $14.2mg\;L^{-1}$, and Seonam reservoir had the highest deviation in BOD. The maximum BOD for every lake was in February and their minimum in May, except for Lake Hoeya whose minimum was in July. The means of various nutrients were as follows: TN $0.051mg\;L^{-1}$, TP $0.100mg\;L^{-1}$, $NH_3-N\;0.606mg\;L^{-1}$, and $NO_3-N\;0.014mg\;L^{-1}$. The maximum TN was measured in June and the maximum and minimum TP were measured in March and in May respectively in the four lakes. Benthic macroinvertebrates were surveyed in April and October 2010. The number of benthic macroinvertebrates species was in the range of 16~36 and the average number of individuals were 58~208 inds. $m^{-2}$. Seonam reservoir, which has the highest mean TN ($0.082mg\;L^{-1}$) and $NO_3-N$($0.023mg\;L^{-1}$), had the largest number of species (36 species, 208 inds. $m^{-2}$). Pearson's correlation between the number of macro invertebrates species and TN was 0.962 (P<0.05), and between the species and $NO_3-N$ was 0.999 (P<0.05). These results show that the number of benthic macroinvertebrates species of the four lakes in Ulsan-si is significantly correlated with TN and $NO_3-N$.