• 한국수처리학회지
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• 제26권6호
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• pp.3-12
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• 2018

The objective of this study was to evaluate the radius of influence of effluent of water treatment system developed for the purpose of improvement of reservoir water quality using fluorescent dye (Rhodamine-WT) tracer experiment and 3-D numerical model. The tracer experiment was carried out in a medium-sized agricultural reservoir with a storage capacity of $227,000m^3$ and an average depth of 1.6 m. A guideline with a total length of 160 m was installed at intervals of 10 m in the horizontal direction from the discharge part, and a Rhodamine measurement sensor (YSI 6130, measurement range $0-200{\mu}g/L$) was used to measure concentration changes in time, distance, and depth. Experimental design was established in advance through Jet theory and the diffusion process was simulated using ELCOM, a three dimensional hydraulic dynamics model. As a result of the study, the direct effect radius of the jet emitted from the applied water treatment system was about 50-70 m, and the radius of physical effect by the advection diffusion was judged to be 100-120 m. The numerical simulations of effluent advection-diffusion of the water treatment system using ELCOM showed very similar results to those of the impact radius analysis using the tracer experiment and jet flow empirical equations. The results provide valuable information on the spatial extent of the water quality improvement devices installed in the reservoir and the facility layout design.

• 한국환경과학회지
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• 제30권2호
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• pp.185-189
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• 2021

This study was conducted to determine and to standardize the time of emergence of Protaetia brevitarsis adults, through four breeding experiments, including one which selected the dominant individuals of Protaetia brevitarsis. The breeding experiments were divided into two groups with hibernating and non-hibernating Protaetia brevitarsis by placing 100, 150, 200, 250 and 300 Protaetia brevitarsis in each breeding box (50 cm × 35 cm × 15 cm) filled with 12 L of fermented sawdust. Breeding tests were with four replicates each for 3 months. The test period was classified into four stages: Exp. 1 (Sep 1, 2019 to Nov 30, 2019), Exp. 2 (Dec 1, 2019 to Feb 29, 2020), Exp. 3 (Mar 1, 2019 to May 31, 2020) and Exp. 4 (Jun 1, 2020 to Aug 31, 2020). The survey items included average dead number, average emergence number, average mortality, and average emergence rate. In Exp. 1 and 2, the changes in Protaetia brevitarsis adults were similar. In Tables 1 and 2, the allegorical changes of adult white-spotted flowers were similar. In addition, the average dead number, average emergence number, average mortality, and average emergence rate showed better results in the hibernation state than in both Exp. 1 and 2. Exp. 3 and 4 showed a pattern of change different from the results of Exp. 1 and 2 and these characteristics were superior in the hibernation states compared to the non-hibernation states. In conclusion, this result was found to be most appropriate as a standardization of the emergence time of 200 Protaetia brevitarsis treatments through four breeding experiments in the hibernating state.

• 농촌계획
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• 제28권2호
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• pp.41-50
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• 2022

The primary purpose of this study is to identify various factors that affect farmland prices according to changes in the actual transaction price of farmland over the past decade, and to use this to derive policy implications for price stabilization. To this end, the farmland price model are constructed at the parcel level in the case area (Namwon-si, Jinju-si). The analysis method is based on the Hedonic price function, and the OLS and the quantile regression are used for the parcel level model. As a result of estimating the parcel level farmland price model in the case area, the larger the parcel area, the lower the farmland price, and the higher the farmland price outside the agricultural promotion area. It was found that there was a price difference according to the type of special purpose areas, and the location characteristics showed some differences across the cities. The farmland price models presented in this study are suitable for identifying the factors affecting farmland prices, and are expected to be highly utilized in that it is possible to construct flexible variables suitable for regional characteristics.

• Journal of Forest and Environmental Science
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• 제38권2호
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• pp.90-101
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• 2022

The study aims to assess composition, diversity and population indices of natural regeneration of woody species in Jebel El Gerrie forest reserve, Blue Nile State, Sudan. We conducted field work between December 2018 and January 2019. We used random sampling to collect vegetation data in the forest where we made a total of 90 circular sample plots (radius 17.84 m) and distributed them proportionally to the area of each of the four density-based vegetation classes of the forest i.e. high density (C1), medium density (C2), low density (C3) and crop land (C4). In each sample plot we identified all regenerating tree species and counted their regeneration frequencies. We calculated ecological metrics of regeneration frequency, density, abundance, richness, evenness, diversity and importance value index (IVI) and drew abundance rank curve. Results revealed that out of fifteen mature tree species present, natural regeneration of 8 species, which belong to 6 families, was observed. The relatively most frequently naturally regenerating and abundant species were Anogeissus leiocarpa and Combretum hartmannianum. Richness, evenness and diversity of regenerating species were 1.33, 0.82 and 1.7, respectively. One-way ANOVA (α=0.05) of mean regeneration densities disclosed that there were significant differences (F_3,86=16.77, p=0.000) between C2 & C3 (p=0.000) and C2 & C4 (p=0.000). While regeneration of seven tree species were absent, two, two and four species were of good, poor and fair regeneration status, respectively. A comparison of mean density of natural regeneration with that of parent trees reflects a poor regeneration status of the forest. The study provides empirical results on the regeneration status of species and signifies the need for management interventions for species conservation and restoration, maintenance of biodiversity and sustainable production.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권3호
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• pp.22-40
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• 2022

The goal of this study was to estimate the possible scattering distance of deicer from the highway and the impact range of deicer on soil quality in terms of plant growth. Among the major elements (Ca²⁺, Cl^- and Na⁺) of deicer, Ca²⁺and Cl^- are usually applied as fertilizer to soil. Therefore both elements (Ca²⁺and Cl^-) were not appropriate for a tracer of deicer at the agricultural area. In this study, SAR (sodium adsorption ratio) of soil was proposed as an alternative tracer to confirm the distribution of the deicer around the highway areas. Because deicer is the main anthropogenic source of Na⁺ around the highway areas and does harm to the physical properties of soil and plant growth through the destruction of soil aggregate, SAR would be an recommendable tracer to access the distribution of deicer as well as adverse effect on soil quality at highway areas. The influence range of deicer based on SAR of soil was estimated to be less than 20 m distance from the highway even though the possible flying distance of deicer was found to be more than 100 m from the highway. However the deicer seriously deposited within 10 m from the highway.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권5호
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• pp.1-9
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• 2022

A correlation analysis was performed to investigate differences in the response of surface water and groundwater to drought using the Standardized Precipitation Index (SPI). Water level data of 20 agricultural reservoirs, 4 dams, 2 rivers, and 8 groundwater observation wells were used for the analysis. SPI was calculated using precipitation data measured at a nearby meteorological station. The water storage of reservoirs and dams decreased significantly as they responded sensitively to the drought from 2014 to 2016, showing high correlation with SPI of the relatively long accumulation period (AP). The responses of rivers varied greatly depending on the presence of an upstream dam. The water level in rivers connected to an upstream dam was predominantly influenced by the dam discharge, resulting in very weak correlation with SPI. On the contrary, the rivers without dam exhibited a sharp water level rise in response to precipitation, showing higher correlation with SPI of a short-term AP. Unlike dams and reservoirs, the responses of groundwater levels to precipitation were very short-lived, and they did not show high correlation with SPI during the long-term drought. In drought years, the rise of groundwater level in the rainy season was small, and the lowered water level in the dry season did not proceed any further and was maintained at almost the same as that of other normal years. Conclusively, it is confirmed that groundwater is likely to persist longer than surface water even in the long-term drought years.

• Journal of Forest and Environmental Science
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• 제38권3호
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• pp.174-183
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• 2022

The study aims to examine population indices of mature trees in Jebel Elgarrie forest, Blue Nile State, Sudan. We used remote sensing techniques to stratify the forest into vegetation classes depending on tree density. We distributed 97 circular sample plots (0.1 ha) proportionally to the area of the vegetation classes. In each sample plot we identified, counted and recorded all mature trees (DBH ≥10 cm). We calculated frequency, density, abundance, richness, evenness and diversity for each species and we drew abundance rank curve of mature trees. We used One-Way ANOVA to test for differences (α=0.05) in mean density (No./ha) of mature trees between vegetation classes. Results revealed that the forest was conveniently sub-divided into high density (C1), medium density (C2), low density (C3) and bare farm land (C4) classes. We identified fifteen tree species that belong to 10 families and 14 genera. Combretaceae and Fabaceae were the common families while Anogeissus leiocarpa was the most frequently occurring species. While species diversity varied between vegetation classes, diversity of the forest as a whole is low. While mean density of mature trees in C1, C2, C3 and C4 it was 100, 74, 10, and 0, respectively, it was 54 for the whole forest indicating low stocking, Following One-Way ANOVA, multiple comparisons revealed significant differences in mean density of mature trees between C1 & C3 and C2 & C3. The study provided empirical results on population indices of mature tree species, which would be of importance for successful management and conservation of the forest.

• 한국지구과학회지
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• 제43권1호
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• pp.110-118
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• 2022

빈번한 가뭄의 피해는 수자원의 양극화를 초래하고 있다. 국내에서는 2011년부터 2017년 사이에 국지적이고 주기적인 이상 가뭄이 지속되어 10년 가뭄 빈도로 설계된 소규모 저수지의 저수율이 감소하였다. 이러한 저수율의 감소는 수질을 떨어트릴 수 있고 이미 확보된 용수의 사용마저 제한할 수 있다. 따라서 가뭄에 대비하고 극복하기 위해서는 수질관리와 가뭄 빈도의 재산정이 필요하다. 이 연구는 저수지에서 수질 변화의 원인인 잠재적 오염물질을 추정하고, 가뭄 기간 동안 저수지의 저수율 감소와 그에 따른 수질 변화를 검토한 것이다.

• 한국물환경학회지
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• 제39권1호
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• pp.9-19
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• 2023

Drought is a natural disaster that can have serious social impacts. Drought's impact ranges from water supply for humans to ecosystems, but the impact of drought on river water quality requires careful investigation. In general, drought occurs meteorologically and is classified as agricultural drought, hydrological drought, and environmental drought. In this study, the BOD environmental drought is defined using the bivariate copula joint probability distribution model between the meteorological drought index and the river BOD, and based on this, the environmental drought condition index (EDCI-BOD) was proposed. The results of examining the proposed index using past precipitation and BOD observation data showed that EDCI-BOD expressed environmental drought well in terms of river BOD water quality. In addition, by classifying the calculated EDCI-BOD into four levels, namely, 'attention', 'caution', 'alert', and 'seriousness', a practical monitoring stage for environmental drought of BOD was constructed. We further estimated the sensitivity of the stream BOD to meteorological drought, and through this, we could identify the stream section in which the stream BOD responded relatively more sensitively to the occurrence of meteorological drought. The results of this study are expected to provide information necessary for river BOD management in the event of meteorological droughts.

• 농촌계획
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• 제28권4호
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• pp.69-81
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• 2022

The change in farmland price has almost always been focused on not only farmers but policy-decision makers; for farmers to get information before purchasing farmland; for policy-decision makers to use appropriate policy tools to stabilize the market. So far the change in farmland price has been calculated as a form of average change on a year-to-year base. Such calculations have become one of the causes which lead to misunderstanding of the farmland market because the year-to-year average change includes changes in price as well as changes in the number of trades and sizes of traded farmland. This paper is designed to suggest a proper method of building a price index for farmland as a tool to review the price change. We considered the applicability of several types of price indices and concluded that a Laspeyres-type price index is the most reasonable choice. A Laspeyres-type price index, however, has a shortcoming in which a reference year's weight may affect the whole period of an index. Thus, we also suggest two other weights, a three-year average including a reference year and a share of farmland. All indices show that farmland prices have risen significantly in recent 10 years. We hope that the indices will be developed into one of the government's formal statistics.