• Environmental Engineering Research
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• 제16권3호
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• pp.121-129
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• 2011

The completely mixed flow and plug flow (CAP) water quality model was developed for streams with discontinuous flows, a condition that often occurs in low base flow streams with in-stream hydraulic structures, especially during dry seasons. To consider the distinct physical properties of each reach effectively, the CAP model stream network can include both plug flow (PF) segments and completely mixed flow (CMF) segments. Many existing water quality models are capable of simulating various constituents and their interactions in surface water bodies. More complicated models do not necessarily produce more accurate results because of problems in data availability and uncertainties. Due to the complicated and even random nature of environmental forcing functions, it is not possible to construct an ideal model for every situation. Therefore, at present, many governmental level water quality standards and decisions are still based on lumped constituents, such as the carbonaceous biochemical oxygen demand (CBOD), the total nitrogen (TN) or the total phosphorus (TP). In these cases, a model dedicated to predicting the target concentration based on available data may provide as equally accurate results as a general purpose model. The CAP model assumes that its water quality constituents are independent of each other and thus can be applied for any constituent in waters that follow first order reaction kinetics. The CAP model was applied to the Geum River in Korea and tested for CBOD, TN, and TP concentrations. A trial and error method was used for parameter calibration using the field data. The results agreed well with QUAL2EU model predictions.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제3권3호
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• pp.189-196
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• 1999

The community structure, phytomass, and primary productivity in Thuja orientalis stands on a limestone area located in Maepo-up, Chungbuk province in Korea were estimated quantitatively. Seven species including a small proportion of Quercus dentata were identified in the tree layer, 26 species including Ulmus macrocarpa in the shrub layer, and 79 species including Carex lnceolata in the herb layer of the Thuja stands. The vertical distribution of the fine root phytomass exhibited a power functional decrease relative to the soil depth. The seasonal changes in the fine root phytomass at a soil depth of 5 cm were closely related to the pecipitation in the study area. The productivity of the stand of stems, branches, leaves, and roots were 10.72, 0.82, 0.45 and 6.46 ton DM. $ha^{-1}$ .$yr^{-1}$, respectively. The Thuja stand had a high foliage(25%) and low rate of production per unit of foliage. The annual turnover rate of the fine roots int he Thuja stand was 6.71 $yr^{-1}$. The net primary production of the overstory including the understory was estimated at 19.48 ton DM.$ha^{-1}$.$yr^{-1}$ including an underground section of 6.46 ton DM.$ha^{-1}$.$yr^{-1}$(33%). The allocation ratio of net production to root was lower in the limestone Thuja communities than at the nearby non-limestone ones, whereas the production efficiency to leaf weight was higher in the limestone communities. These results would seem to indicate that the limited production capacity is due to the calcium toxicity and low availability of iron and phosphorus in a limestone soil with a high pH, calcium, and bicarbonate content with a strategy for survival in a hostile habitat.

• Asian-Australasian Journal of Animal Sciences
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• 제8권6호
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• pp.635-639
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• 1995

Digestibility trial was performed with carps weighing 200 g/fish. Fecal collection was made over 7 days using a settling column. The water temperature was in the range of 27 to $30{^{\circ}C}$ during whole experimental period. Fishes were fed 5 diets (Control, $F_{24}S_{13}$, $F_{16}S_{27}$, $F_8S_{40}$ and $F_0S_{56}$) containing both 32%, 24%, 16%, 8% and 0% of fish meal (F) and 0%, 13%, 27%, 40% and 56% of roasted full-fat soybean (S), respectively. Water volume in each recirculated rearing tank was maintained at 130 l with flow rate of 10-12 l/min. Apparent digestibility coefficients (ADCs) of dry matter, protein, lipid, total carbohydrates and energy in diets showed a reduction (p < 0.05) with the increase of dietary full-fat soybean level, although there was no difference in the ADCs between Control and $F_{24}S_{13}$ (p > 0.05). The ADCs of ash, Ca and P in diets significantly increased with the increase of dietary full-fat soybean level, suggesting the high availability of phosphorus in monocalcium phosphate.

• 한국환경농학회지
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• 제18권3호
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• pp.287-291
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• 1999

Mycorrhizae가 형성된 식물에서 인광석이 인산급원으로 이용될 수 있는 지를 검토하기 위하여 온실 실험을 수행하였다. 멸균된 제주 화산회토에 인광석과 용성인비를 100및 200 mg P/kg 수준으로 처리하고 토마토를 재배하였는데 토마토는 mycorrhizae 접종구와 비접종구를 두고 3개월간 재배한 후 식물생육과 인을 비롯한 무기영양소 흡수를 조사하였다. 용성인비 처리구에 비하여 인광석 처리구에서 생육이 현저히 저해되었는데 이는 인광석처리에 따른 토양중의 유효인산 부족 때문일 것이다. 용성인비와 인광석 200 mg P/kg 처리구에스는 mycorrhizae균의 접종에 따라 건물량이 증가하였다. Mycorrhizae 형성율과 토양중의 포자밀도는 인광석 처리구에서 낮았다. 식물체중의 인 함량은 용성인비 처리구에서 높았으며, mycorrhizae 처리 효과는 없었다. N, K, Ca, Mg 등의 함량에서도 처리별로 차이는 없었다. 이상의 결과를 볼 때, 제주 화산회토양에서 $100{\sim}200\;mg\;P/kg$ 수준의 인광석 처리로는 mycorrhizae 형성 여부에 상관없이 적정 식물생육을 위한 인 공급이 될 수 없는 것으로 판단되었다.

• Journal of Ginseng Research
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• 제4권1호
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• pp.104-120
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• 1980

The effects of temperature on transpiration, chlorophyll content, frequency and aperture of stomata, and leaf temperature of Panax ginseng were reviewed. Temperature changes of soil and air under spade roof were also reviewed. Growth responses of responses of ginseng plant at various temperature were assessed in relation to suseptibillity of ginseng plants. Reasonable management of ginseng fields was suggested based on the response of ginseng to various temperatures. Stomata frequency may be increased under high temperature during leaf$.$growing stage. Stomata aperture increased by high temperature but the increase of both frequency and aperture appears not enough for transpiration to overcome high temperature encountered during summer in most fields. Serial high temperature disorder, i.e high leaf temperature, chlorophyll loss, inhibition of photosynthesis, increased respiration and wilting might be alleviated by high humidity and abundant water supply to leaf. High air temperature which limits light transmission rate inside the shade roof, induces high soil temperature(optimum soil temperature 16∼18$^{\circ}C$) and both(especially the latter) are the principal factors to increase alternaria blight, anthracnose, early leaf fall, root rot and high missing rate of plant resulting in poor yield. High temperature disorder was lessen by abundant soil water(optimum 17∼21%) and could be decreased by lowering the content of availability of phosphorus and nitrogen in soil consequently resulting in less activity of microorganisms. Repeated plowing of fields during preparation seems to be effective for sterilization of pathogenic microoganisms by high soil temperature only on surface of soils. Low temperature damage appeared at thowing of soils and emergence stage of ginseng but reports were limited. Most limiting factor of yield appeared as physiological disorder and high pathogen activity due to high temperature during summer(about three months).

• 한국물환경학회지
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• 제35권4호
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• pp.340-351
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• 2019

In this study, the relationship between trophic state indices was analyzed based on the monthly or weekly water quality data of 81 lakes (mostly man-made) in Korea between 2013-2017. Carlson's $TSI_C$ and Aizaki's $TSI_m$ were calculated using the summer (Jun.-Sep.) average data at the upper water layer. The previous Korean trophic state index ($TSI_{KO}$) and the newly suggested index ($TSI_{KON}$) was calculated using the annual average data at the whole layer and at the upper layer, respectively. While previous trophic state index (TSI) such as Carlson's TSI included logarithmic function, we devised newly Monod-type $TSI_{KON}$(Chl) that is 50 when half-saturation concentration of chlorophyll ${\alpha}$ ($Chl.{\alpha}$) measured by UNESCO-method is $10{\mu}gL^{-1}$. MMF-type $TSI_{KON}$(TP) was derived based on the relationship between TP and $Chl.{\alpha}$. A comprehensive $TSI_{KON}$ was decided as the larger one of the two $TSI_{KON}$ values. The range of previous TSI was usually 40-50 for the mesotrophic state, which seemed narrow to discriminate trophic characteristics of the class. The upper limits of $TSI_{KON}$ for oligotrophic, mesotrophic, and eutrophic state were set to 23, 50 and 75, respectively. Classification by $TSI_C$ and $TSI_m$ showed higher frequency of eutrophic class compared to $TSI_{KO}$ and $TSI_{KON}$. This means that the estimation by TSIs developed in foreign natural lakes can lead to distorted results in the classification of the trophic state of Korean lakes. This is due to the decrease of transparency by non-algal material and the reduction in phosphorus availability to algal growth, particularly in Monsoon period.

• 농업과학연구
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• 제48권1호
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• pp.33-43
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• 2021

Along with the widespread use of pesticides in the world, concerns over human health impacts are rapidly growing. There is a large body of evidence on the relationship between the exposure to pesticides and the elevated rate of chronic diseases such as different types of cancers, diabetes, neurodegenerative disorders like Parkinson, Alzheimer, and amyotrophic lateral sclerosis (ALS), birth defects, and reproductive disorders. This research assessed the health risk of pesticide residues by the dietary intake of vegetables collected from the agro-based markets of Dhaka, Bangladesh. As some of the banned pesticides were also found in vegetable samples, they may pose a higher risk because of cheaper availability and hence the government of Bangladesh should take strong measures to control these banned pesticides. Five organo phosphorus (chlorpyrifos, parathion, ethion, acephate, fenthion) and two carbamate (carbaryl and carbofuran) pesticide residues were identified in twenty four samples of two common vegetables (tomato and brinjal). The pesticide residues ranged from below a detectable limit (< 0.01) to 0.36 mg·kg^-1. Acephate, chlorpyrifos, ethion, and carbaryl were detected in only one sample, while co-occurrence occurred twice for parathion. Continuous monitoring and strict regulation should be enforced regarding the control of pesticide residues in fresh vegetables and other food commodities in Bangladesh.

• Journal of Animal Science and Technology
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• 제64권5호
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• pp.885-896
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• 2022

This experiment was conducted to investigate the effects of three different copper (Cu) sources (one inorganic and two organics) and levels (0, 50, and 100 mg/kg) on the growth performance, Cu digestibility, fecal mineral excretion, serum mineral concentration, jejunal morphology, and serum biochemical profile of growing pigs. A total of 42 male, growing pigs (31.08 ± 1.82 kg) were randomly assigned to seven treatments consisting of one negative control (0 mg/kg of added Cu level) and treatments with copper sulfate (CuSO4), Cu-amino acid complex (CuAA), and Cu-hydroxy-4-methylthio butanoate chelate complex (CuHMB) at 50 and 100 mg/kg each for 28 d. Pigs fed 50 or 100 mg/kg of Cu showed improved (p < 0.05) average daily gain and feed intake. Although Cu excretion decreased (p < 0.01) in pigs fed 100 mg/kg of organic Cu sources compared to those fed CuSO4, there was no difference between the Cu sources in pigs fed 50 mg/kg. However, the apparent total tract digestibility of Cu increased (p < 0.01) in pigs fed organic Cu sources compared with that in pigs fed CuSO4. The addition of CuHMB increased (p < 0.01) serum phosphorus and sulfur concentrations; however, there were no effects of source and level on jejunal morphology and serum biochemical profile. These results suggest that the inclusion (50 mg/kg) of organic Cu sources (CuAA and CuHMB) in the growing pig diet could be beneficial for growth performance and Cu availability and may reduce environmental pollution.

• Journal of Forest and Environmental Science
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• 제39권3호
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• pp.180-194
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• 2023

This study characterize, classify and evaluates the function of topography on spatial variability of some selected soil properties to assist in designing land management that support uniform agricultural production. The study site, an agricultural land, was part of the derived savanna zone in southwest Nigeria. Four soil profile pits each were established along two delineated toposequence and described following the FAO/UNESCO guidelines. Samples were collected from the identified genetic horizons. Properties of four soil series developed on different positions of the two delineated Toposequence viz upper, middle, lower slopes and valley bottom positions respectively were studied. The soil samples were analysed for selected physical and chemical properties and data generated were subjected to descriptive and inferential statistics. The results showed that soil colour, depth and texture varied in response to changes in slope position and drainage condition. The sand content ranged from 61 to 90% while the bulk density ranged between 1.06 g cm^-3 to 1.68 g cm^-3. The soils were neutral to very strongly acid with low total exchangeable bases. Available phosphorus value were low while the extractable micronutrient concentration varied from low to medium. Soils of Asejire and Iwo series mapped in the study area were classified as Typic isohyperthermic paleustult, Apomu series as Plinthic isohyperthermic paleustult and Jago series as Aquic psamment (USDA Soil Taxonomy). These soils were correlated as Lixisol, Plinthic Lixisol and Fluvisol (World Reference Based), respectively. Major agronomic constraints of the soils associations mapped in the study area were nutrient availability, nutrient retention, slope, drainage, texture, high bulk density and shallow depth. The study concluded that the soils were not homogenous, shows moderate spatial variation across the slope, had varying potentials for sustainable agricultural practices, and thus, the agronomic constraints should be carefully addressed and managed for precision agriculture.

• 한국환경농학회지
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• 제42권4호
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• pp.382-388
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• 2023

A liquid-type chlorella (LC) produced by self-cultivation is used for strawberry cultivation by farmers in Korea. This study aimed to investigate seedling growth in two strawberry cultivars 'Soraya' and 'Haruhi' after applying solid-type chlorella (SC) in the greenhouse for 30 d. The treatments were as follows: Control, LC (0.2% of 1.0 × 10⁷ cells/mL), ¼ SC (12.5 g/m²), ½ SC (25 g/m²), and SC (50 g/m²). Compared to the control, in the ½ SC treatment, dry weight of the seedlings increased at 30 days after treatment (DAT). Phosphorus content in the leaves of 'Soraya' seedlings of the SC treatment increased compared to that of the control. At 10 and 30 DAT, photosynthetic pigments including chlorophylls and carotenoids in the seedlings of both cultivars increased with the ½ SC treatment. These results indicate that the application of SC improved the growth of strawberry seedlings and could replace LC.