• Geotechnical Engineering
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• v.8 no.1
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• pp.81-102
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• 1992

Landslides on hillside slopes with shallow soil cover over a sloping bedrock are frequently caused by increases in porewater pressures following of heavy rainfall and it is one of the most important factors of assessing the risk of landslide to predict the groundwater level fluctuations in hillslopes. This paper presents the comparative study of three unsaturated flow models developed by Sloan et al., Reddi, L.N., and Thomas, H.A., Jr., respectively, which are used to predict the increase of groundwater levels in hillside slopes. The parametric study for each of models is also presented. The Kinematic Storage Model(KSM) developed by Sloan et at. is utilized to predict the saturated groundwater flow. They are applied to the two sites in Korea so as to examine the possibility of use in the groundwater flow model. The results show that two unsaturated models developed by Sloan et al. and Reddi, L. N. are largely affected by the uncertain parameters like saturated permeability and saturated water content : the abed model has the potential of use in unsaturated flow model with the optimal estimates of model parameters utilizing available optimization techniques. And it is also found that the KSM must be modified to account for the time delay effect in the saturated zone. The results of this paper are able to be utilized in developing the predictive model of groan dwater level fluctuations in a hillslope.

• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.55-61
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• 2011

Forty yeast strains isolated from soils taken from different locations in Egypt were tested for their P-solubilizing activities on the basis of analyzing the clear zone around colonies growing on a tricalcium phosphate medium after incubation for 5 days at $25^{\circ}C$, denoted as the solubilization index (SI). Nine isolates that exhibited P-solubilization potential with an SI ranging from 1.19 to 2.76 were genetically characterized as five yeasts belonging to the genus Saccharomyces cerevisiae and four non-Saccharomyces, based on a PCR analysis of the ITS1-26S region amplied by SC1/SC2 species-specific primers. The highest P-solubilization efficiency was demonstrated by isolate PSY- 4, which was identified as Saccharomyces cerevisiae by a sequence analysis of the variable D1/D2 domain of the 26S rDNA. The effects of single and mixed inoculations with yeast PSY-4 and Bacillus polymyxa on the P-uptake and growth of corn were tested in a greenhouse experiment using different levels of a phosphorus chemical fertilizer (50, 100, and 200 kg/ha super phosphate 15.5% $P_2O_5$). The results showed that inoculating the corn with yeast PSY-4 or B. polymyxa caused significant increases in the shoot and root dry weights and P-uptake in the shoots and roots. The P-fertilization level also had a significant influence on the shoot and root dry weights and P-uptake in the shoots and roots when increasing the P-level from 50 up to 200 kg/ha. Dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 200 kg/ha gave higher values for the shoot and root dry weights and P-uptake in the shoots and roots, yet these increases were nonsignificant when compared with dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 100 kg/ha. The best increases were obtained from dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 100 kg/ha, which induced the following percentage increases in the shoot and root dry weights, and P-uptake in the shoots and roots; 16.22%, 46.92%, 10.09%, and 31.07%, respectively, when compared with the uninoculated control (fertilized with 100 kg/ha).

• Journal of Biosystems Engineering
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• v.35 no.5
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• pp.343-349
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• 2010

Rapid on-site sensing of nitrate-nitrogen and potassium ions in hydroponic solution would increase the efficiency of nutrient use for greenhouse crops cultivated in closed hydroponic systems while reducing the potential for environmental pollution in water and soil. Ion-selective electrodes (ISEs) are a promising approach because of their small size, rapid response, and the ability to directly measure the analyte. The capabilities of the ISEs for sensing nitrate and potassium in hydroponic solution can be affected by the presence of other ions such as calcium, magnesium, sulfate, sodium, and chloride in the solution itself. This study was conducted to investigate the applicability of two ISEs consisting of TDDA-NPOE and valinomycin-DOS PVC membranes for quantitative determinations of $NO_3$-N and K in hydroponic solution. Nine hydroponic solutions were prepared by diluting highly concentrated paprika hydroponic solution to provide a concentration range of 3 to 400 mg/L for $NO_3$-N and K. Two of the calibration curves relating membrane response and nutrient concentration provided coefficients of determination ($R^2$) > 0.98 and standard errors of calibration (SEC) of < 3.79 mV. The use of the direct potentiometry method, in conjunction with an one-point EMF compensation technique, was feasible for measuring $NO_3$-N and K in paprika hydroponic solution due to almost 1:1 relationships and high coefficients of determination ($R^2$ > 0.97) between the levels of $NO_3$-N and K obtained with the ion-selective electrodes and standard instruments. However, even though there were strong linear relationships ($R^2$ > 0.94) between the $NO_3$-N and K concentrations determined by the Gran's plot-based multiple standard addition method and by standard instruments, hydroponic $NO_3$-N concentrations measured with the ISEs, on average, were about 10% higher than those obtained with the automated analyzer whereas the K ISE predicted about 59% lower K than did the ICP spectrometer, probably due to no compensation for a difference between actual and expected concentrations of standard solutions directly prepared.

• Journal of Bio-Environment Control
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• v.16 no.3
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• pp.186-193
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• 2007

Effects of deficit irrigation by different soil moisture-based water potential on the reduction of green shoulder fruits in fresh tomato were investigated. Deficit irrigation with -30 kPa treatment significantly reduced green shoulder fruit by 53.7% compared to the -15 kPa treatment. The total concentrations of potassium in levels of whole fruit was not different between normal red fruit (NRF) and green shoulder fruit (GSF). However, the concentrations of potassium in distal part of GSF lower than that of a basal part of GSF Total soluble sugar contents in NRF and GSF were increased during the maturation periods. Contents of starch in NRF and distal part of GSF were decreased during the maturation periods. However, contents of starch in basal part of GSF was not change during the maturation periods. Activity of sucrose phosphate synthase was higher in NRF than that of GSF. Activity of acid invertase in NRF and GSF decreased rapidly during the maturation periods. Activity of acid invertase was significantly different in distal and basal part of GSF. Total activities of peroxidase and alcohol dehydrogenase in NRF were higher than that of GSF.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.7-7
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• 2017

Unfavorable weather and soil conditions reduce rice yield and land and water productivity, aggravating existing encounters of poverty and food insecurity. These conditions are foreseen to worsen with climate change and with the unceasing irrational human practices that progressively debilitate productivity despite global appeals for more food. Our understanding of plant responses to abiotic stresses is advancing and is complex, involving numerous critical processes - each controlled by several genetic factors. Knowledge of the physiological and molecular mechanisms involved in signaling, response and adaptation, and in some cases the genes involved, is advancing. Moreover, the genetic diversity being unveiled within cultivated rice and its wild relatives is providing ample resources for trait and gene discovery, and this is being scouted for rice improvement using modern genomics and molecular tools. Development of stress tolerant varieties is now being fast-tracked through the use of DNA markers and advanced breeding strategies. Large numbers of drought, submergence and salt tolerant varieties were commercialized over recent years in South and Southeast Asia and more recently in Africa. These varieties are making significant changes in less favorable areas, transforming lives of smallholder farmers - progress considered incredulous in the past. The stress tolerant varieties are providing assurance to farmers to invest in better management of their crops and the ability to adjust their cropping systems for even higher productivity and more income, sparking changes analogous to that of the first green revolution, which previously benefited only favorable irrigated and rainfed areas. New breeding tools using markers for multiple stresses made it possible to develop more resilient, higher yielding varieties to replace the aging and obsolete varieties still dominating these areas. Varieties with multiple stress tolerances are now becoming available, providing even better security for farmers and lessening their production risks even in areas affected by complex and overlapping stresses. The progress made in these less favorable areas triggered numerous favorable changes at the national and regional levels in several countries in Asia, including adjusting breeding and dissemination strategies to accelerate outreach and enabling changes at higher policy levels, creating a positive environment for faster progress. Exploiting the potential of these less productive areas for food production is inevitable, to meet the escalating global needs for more food and sustained production systems, at times when national resources are shrinking while demand for food is mounting. However, the success in these areas requires concerted efforts to make use of existing genetic resources for crop improvement and establishing effective evaluation networks, seed production systems, and seed delivery systems to ensure faster outreach and transformation.

• Journal of Environmental Health Sciences
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• v.35 no.1
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• pp.21-35
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• 2009

The Asian dust storms which originated in the deserts of Mongolia and China transported particles to Korea and led to a high concentration of atmospheric particulate matters (PM) of more than $1000{\mu}g/m^3$ throughout the country in the spring, of 2007. Public concern, in Korea, about the possible adverse effects of these dust events has increased, as these dust storms can contain various air pollutants emitted from heavily industrialized eastern China. The objectives of this study were to understand the concentration characteristics of PM as a function of particle size between the Asian dust storm episodes and non-Asian dust period and to consider the mass size distribution of PM in the Asian dust storms and their water soluble ion species on the potential, possible effects on deposition levels in the three regions (nasopharyngeal, tracheobronchial, and alveolar) of the human respiratory system. The size distribution of PM mass concentration during the Asian dust storms showed a peak in the coarse particle region due to the long-range transport of soil particles from the deserts of Mongolia and China, which was identified by HYSPLIT-4 model for backward trajectory analysis of air arriving in the sampling site of Iksan. During the non-Asian dust period, there were two different types in PM size distribution: bimodal distribution when low concentrations of $PM_{2.5}$ were observed, while unimodal distribution having a peak in fine particle region when high concentrations of $PM_{2.5}$ were showed. This unimodal distribution with high concentrations of fine particulate and secondary air pollutants such as ${SO_4}^{2-}$, ${NO_3}^-$, ${NH_4}^+$ was found to be due to the long-range transport of air pollutants from industrialized eastern China. During the Asian dust storms, the mean concentrations of PM that can be deposited in the nasopharyngeal, tracheobronchial, and alveolar region were $128.8{\mu}g/m^3$, $216.5{\mu}g/m^3$, and $89.6{\mu}g/m^3$, respectively. During the non-Asian dust period, the mean concentrations of PM that can be deposited in the nasopharyngeal, tracheobronchial, and alveolar region were $8.4{\mu}g/m^3$, $9.5{\mu}g/m^3$ and $38.5{\mu}g/m^3$, respectively.

• Korean Journal of Weed Science
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• v.7 no.2
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• pp.156-164
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• 1987

Allelopathic activity of dominant upland weed species was determined using aqueous and methanol extracts and dried residues of the weeds. Germination and seedling growth of radish (Raphanus sativus L.) and sesame (Sesamum indicum L.) were greatly inhibited by 2% (w/v) aqueous extracts of Artemisia asiatica Nakai and Portulaca oleracea L., respectively. Great phytotoxicity on both indicator plants occurred by 2% (w/v) aqueous extracts of Capsel/a bursa-pastoris (L.) Medik. A complete inhibition in germination and seedling growth of radish was caused by 2% (w/v) methanol extract of A. asiatica. There was about 90% inhibition in germination and seedling growth of sesame due to 2% (w/v) methanol extracts of A. asiatica, P. oleracea and Trifolium repens L. Phytotoxic effects varied with extract solution, weed species and indicator plants employed, indicating that the weed species contained different contents and kinds of allelopathic chemicals. Water potential and pH adjusted to those of the extracts did not affect germination and seedling growth of the indicator plants. Phytotoxicity increased with increasing concentration of the extracts obtained from four suspected alleopathic weeds. Soil-incorporated plant residues of A. asiatica and P. oleracea caused greater phytotoxicity on radish than those of C. bursa-pastoris and T. repens.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.1
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• pp.3-14
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• 2018

An apartment complex is a building use with great potential to contribute to solving problems related to urban ecological environment and climate change. The first goal of this study is to grasp the current situation of application and limitations of the ecological area rate, which is a representative evaluation index used to evaluate the environmental performance of the external space of an apartment complex in Green Standard for Energy and Environmental Design (G-SEED). The second goal is to propose a prototype of the evaluation index for evaluating greenhouse gas (GHG) reduction performance in order to supplement the evaluation index for the environmental performance of the external space in terms of response to climate change. We analyzed 43 cases of apartment complexes certified according to G-SEED, which was enforced since July 1, 2010, and found application characteristics of each space type and the limitations of ecological area rate. We analyzed overseas green building certification systems such as LEED and BREEAM that derived implications for supplementing the limitations of ecological area rate, which is focused on the evaluation of soil and water circulation function, and set up a development direction of complementary measures. Through analysis of previous studies, relevant regulations and standards, and technical documents of the manufacturer, the heat island mitigation performance of the pavement and roof surfaces of the apartment complex and the carbon uptake performance of the trees in the apartment complex was selected as parameters to yield the GHG reduction performance of the external space of the apartment complex. Finally, a quantitative evaluation method for each parameter and a prototype of the evaluation index for the GHG reduction performance were proposed. As a result of applying the prototype to an apartment complex case, the possibility of adoption and applicability as an evaluation index of G-SEED were proved.

• Journal of Wetlands Research
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• v.25 no.2
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• pp.132-144
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• 2023

The use of constructed wetlands (CWs) to sequester carbon has been a topic of interest in recent studies. However, CWs have been found to be both carbon sinks and carbon sources, thus leaving uncertainties about their role in carbon neutrality initiatives. To address the uncertainties, a bibliometric and comprehensive review on carbon sequestration in CWs was conducted. Upon forming various scripts using CorText Manager, it was found that a majority of the studies focused on the effectiveness of CWs to remove nutrients, particularly nitrogen. The results of the comprehensive review revealed that high carbon concentrations and carbon sequestration rates in CW soils are dependent on the vegetation types used, the ages of the CWs, and the organic content of inflow water entering the CWs. The Typha genus was the most dominant plant genus used in the CWs from the reviewed studies and was associated with the highest carbon sequestration rates documented in this review study. Furthermore, the relatively high ability of tree species, in comparison to emergent plants, to sequester carbon was observed. Therefore, incorporating tree species into CW designs and adding them to emergent plants is seen as a potential breakthrough approach to improve the ability of CWs to sequester carbon and ultimately contribute to mitigating climate change.

• Journal of the Korean GEO-environmental Society
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• v.25 no.6
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• pp.19-24
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• 2024

Urban densification has necessitated the development of subterranean spaces such as subway networks and underground tunnels to facilitate the dispersal and movement of populations. Development of these underground spaces requires excavation from the ground surface, which can induce groundwater flow and potentially lead to ground subsidence and sinkholes, damaging structures. To mitigate these risks, it is essential to model groundwater flow prior to construction, analyze its characteristics, and predict potential groundwater discharge during excavation. In this study, we collected meteorological, topographical, and soil conditions data for the city of ○○, where tunnel construction was planned. Using the Visual MODFLOW program, we modeled the groundwater flow. Excavation sections were set as drainage points to monitor groundwater discharge during the excavation process, and the effectiveness of seepage control measures was assessed. The model was validated by comparing measured groundwater levels with those predicted by the model, yielding a coefficient of determination of 0.87. Our findings indicate that groundwater discharge is most significant at the beginning of the excavation. Additionally, the presence of seepage barriers was found to reduce groundwater discharge by approximately 59%.