• Journal of Wetlands Research
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• v.25 no.2
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• pp.99-110
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• 2023

Non-point source (NP) pollutants in an agricultural landuse are discharged from a large area compared to those in other land uses, and thus effective source control measures are needed. To develop appropriate control measures, it is necessary to quantify discharge load of each source and evaluate the degree of water quality improvement by implementing different options of the control measures. This study used Hydrological Simulation Program-FORTRAN (HSPF) to quantify pollutant discharge loads from different sources and effects of different control measures on water quality improvements, thereby supporting decision making in developing appropirate pollutant control strategies. The study area is the Gyeseong river watershed in Changnyeong county, Gyeongsangnam-do, with agricultural areas occupying the largest proportion (26.13%) of the total area except for the forest area. The main pollutant sources include chemical and liquid fertilizers for agricultural activities, and manure produced from small scale livestock facilities and applied to agriculture lands or stacked near the facilities. Source loads of chemical fertilizers, liquid fertilizers and livestock manure of small scale livestock facilities, and point sources such as municipal wastewater treatment plants (WWTPs), community WWTPs, private sewage treament plants were considered in the HSPF model setup. Especially, NITR and PHOS modules were used to simulate detailed fate and transport processes including vegitation uptake, nutrient deposition, adsorption/desorption, and loss by deep percolation. The HSPF model was calibrated and validated based on the observed data from 2015 to 2020 at the outlet of the watershed. The calibrated model showed reasonably good performance in simulating the flow and water quality. Five Pollutants control scenarios were established from three sectors: agriculture pollution management (drainge outlet control, and replacement of controlled release fertilizers), livestock pollution management (liquid fertilizer reduction, and 'manure management of small scale livestock facilities) and private STP management. Each pollutant control measure was further divided into short-term, mid-term, and long-term scenarios based on the potential achievement period. The simulation results showed that the most effective control measure is the replacement of controlled release fertilizers followed by the drainge outlet control and the manure management of small scale livestock facilities. Furthermore, the simulation showed that application of all the control measures in the entire watershed can decrease the annual TN and TP loads at the outlet by 40.6% and 41.1%, respectively, and the annual average concentrations of TN and TP at the outlet by 35.1% and 29.2%, respectively. This study supports decision makers in priotizing different pollutant control measures based on their predicted performance on the water quality improvements in an agriculturally dominated watershed.

• Polymer(Korea)
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• v.36 no.2
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• pp.177-181
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• 2012

This study presents the preparation of double emulsions in a poly(dimethylsiloxane) (PDMS)-based microfluidic device. To improve the wettability of hydrophilic continuous phase onto a hydrophobic PDMS microchannel, the surface was modified with 3-(trimethoxysilyl) propyl methacrylate (TPM) and then sequentially reacted with acrylic acid monomer solution, which produced selective covalent bonding between acrylic acids and methacrylate groups. For the proof of selective surface modification, tolonium chloride solution was used to identify the modified region and we confirmed that the approach was successfully performed. When water containing 0.5% w/w sodium dodecyl sulfate and 1% w/w Span80 with hexadecane were loaded into the selectively modified microfluidic channels, we can produce stable double emulsion. Based on the spreading coefficients, we predict the morphology of double emulsions. Our proposed method efficiently produces monodisperse double emulsions having 48.5 ${\mu}m$(CV:1.6%) core and 65.1 ${\mu}m$ (CV:1.6%) shell. Furthermore, the multiple emulsions having different numbers of core were easily prepared by simple control of flow rates.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.10
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• pp.867-873
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• 2001

The purpose of this study is to find analytic solution of determining the optimal capacity (lot-size) of multiproduct acyclic multistage production and inventory system to meet the finished product demand under the constraint of finite intermediate storage. Intermediate storage is a practical way to mitigate the material flow imbalance through the line of supply and demand chain. However, the cost of constructing and operating storage facilities is becoming substantial because of increasing land value, environmental and safety concern. Therefore, reasonable decision-making about the capacity of processes and storage units is an important subject for industries. The industrial solution for this subject is to use the classical economic lot sizing method, EOQ/EPQ(Economic Order Quantity/Economic Production Quantity) model, incorporated with practical experience. But EOQ/EPQ model is not suitable for the chemical plant design with highly interlinked processes and storage units because it is developed based on single product and single stage. This study overcomes the limitation of the classical lot sizing method. The superstructure of the plant consists of the network of serially and/or parallelly interlinked non-continuous processes and storage units. The processes transform a set of feedstock materials into another set of products with constant conversion factors. A novel production and inventory analysis method, PSW(Periodic Square Wave) model, is applied to describe the detail material flows among equipments. The objective function of this study is minimizing the total cost composed of setup and inventory holding cost. The advantage of PSW model comes from the fact that the model provides a set of simple analytic solutions in spite of realistic description of the material flows between processes and storage units. the resulting simple analytic solution can greatly enhance the proper and quick investment decision for the preliminary plant design problem confronted with economic situation.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.83-89
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• 1999

Butterhead lettuce was grown hydroponically in a plant factory during summer season. To decrease the occurrence of tipburn and increase productivity, optimum cultivars, substrates, gully slope and height, and the amount of irrigation were evaluated in this experiment. Cultivars ‘Rex’ and ‘Flandria’ showed higher productivity with less tipburn as compared to the others in spite of lower growth rates and appeared to be suitable cultivars during summer season. Cocopeat showed high productivity due to superior physio-chemical characteristics. Appropriate gully slope which makes nutrient solution easy to flow was shown to be 1 to 2%. The amount of irrigation was appropriate at 2$\ell$/gully. Higher growth of the butterhead lettuce observed when the bed was at a lower position. Low bed was thought to be good for lettuce growth with proper humidity and average temperatures.

• Natural Product Sciences
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• v.16 no.4
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• pp.233-238
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• 2010

In order to facilitate the quality control of Artemisia capillaris, a simple, accurate and reliable HPLC method was developed for the simultaneous determination of the six bioactive compounds: scopolin (1), chlorogenic acid (2), 2,4-dihydroxy-6-methoxyacetophenone 4-glycoside (3), hyperoside (4), isorhamnetin 3-Orobinobioside (5), and scoparone (6), which were selected as the chemical markers of A. capillaris. Separation was achieved on an Agilent Eclipse XDB-C18 column with a gradient solvent system of 0.1% trifluoroacetic acid aqueous-acetonitrile at a flow-rate of 1.0 mL/min and detected at 254 nm. All six calibration curves showed good linearity ($R^2$ > 0.998). A simple reversed phase HPLC method was developed for extracting pharmacologically active compounds scopolin, chlorogenic acid, 2,4-dihydroxy-6-methoxyacetophenone 4-glycoside, hyperoside, isorhamnetin 3-O-robinobioside, and scoparone from A. capillaris using a binary gradient of acetonitrile : 0.1% trifluoroacetic acid with UV detection at 254 nm. The scopolin (1), chlorogenic acid (2), 2,4-dihydroxy-6-methoxyacetophenone 4-glycoside (3), hyperoside (4), isorhamnetin 3-O-robinobioside (5), and scoparone (6) contents of the herb of A. capillaris collected from fifteen district markets in Korea were 0.00~0.90 mg/g, 0.06~7.29 mg/g, 0.06~0.91 mg/g, 0.07~5.05 mg/g, 0.42~13.11 mg/g, and 1.11~29.82 mg/g, respectively. The results demonstrated that this method is simple and reliable for the quality control of A. capillaris.

• Journal of Environmental Health Sciences
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• v.30 no.2
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• pp.92-97
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• 2004

Three methods for VOCs emissions control in indoor air are reduction at the source, ventilation between indoor and outdoor, and removal. The best alternative should be to replace highly emitting sources with sources having low emissions, but the pertinent information on VOCs is not always available from manufactures. Other ways of improving indoor air quality are needed. It is to increase the outside fresh-air flow to dilute the pollutants, but this method would generally provide only a dilution effect without destruction in residence. An ideal alternative to existing technologies would be a chemical oxidation process able to treat large volumes of slightly contaminated air at normal temperature without additional oxidant such as ozone generator and ion generator. Photocatalytic oxidation(PCO) represents such a process. It is characterized by a surface reaction assisted by light radiation inducing the formation of superoxide, hydroperoxide anions, or hydroxyl radicals, which are powerful oxidants. In comparison with other VOCs removal methods, PCO offers several advantages. The purpose of this study was to explore the possibilities for photocatalytic purification of slightly contaminated indoor air by using visible light such as flurescent visible light(FVL). In this study, a PCO of relatively concentrated benzene using common FVL lamps was investigated as batch type and total volatile organic compounds(TVOCs) using a common FVL lamp and penetrated sun light over window. The results of this study shown the possibility of TiO$_2$ photocatalyst application in the area of indoor air quality control.

• Macromolecular Research
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• v.8 no.4
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• pp.179-185
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• 2000

Generally vascular grafts with a relatively large inner diameter (> 5 mm) have been successfully employed for replacement in the human body. However, the use of small diameter grafts is limited, because these grafts rapidly occlude due to the thrombosis. The ideal blood-contacting surface of a prosthesis would be an endothelial cell (EC) lining, because the confluent monolayer of healthy ECs that culture natural blood vessels represents the ideal nonthrombogenic surface. For vascular graft application, the stable EC adhesion on surface under How conditions is very important. In this study, the adhesive strength of ECs attached on polymer surfaces coated with collagen type IV (Col IV), fibronectin (Fn), laminin (Ln), and treated with corona was investigated onto polyurethane (PU) films. The EC-attached PU surfaces were mounted on parallel-plate flow chambers in a How system prepared for cell adhesiveness test. Three different shear stresses (100, 150, and 200 dyne/㎠) were applied to the How chambers and each shear stress was maintained for 120 min to investigate the effect of shear stress and surface treatment condition on the EC adhesion strength. It was observed that the EC adhesion strength on the surface-modified PU films was in the order of Ln≡Fn > Col IV > corona 》 control. More than 70% of the adhered cells were remained on surface-modified PU surface after applying the shear stress,200 dyne/㎠ for 2 hrs, whereas the cells were completely detached on the control PU surface within 10 min after applying the same shear stress. It seems that the type of adsorbed proteins and hydrophilicitv onto the PU surfaces play very important roles for cell adhesion strength.

• Korean Journal of Pharmacognosy
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• v.36 no.3 s.142
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• pp.177-185
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• 2005

For the purpose of the quality control of Poria cocos, three major compounds were isolated and identified as pachymic acid (1), $3{\beta}-hydroxylanosta-7,9(11),24-trien-21-oic$ acid (2), and dehydroeburicoic acid (3). The optimal extraction conditions for the quantification of pachymic acid its analogues were the 3 hours of reflux with 15g of P. cocos in 100ml 95% ethanol. HPLC conditions were as follows: Column; ZORBAX Eclipse XDB C18 $(4.6{\times}250\;mm,\;Agillent)$, mobile phase; 1% HOAc in 70% $MeOH{\rightarrow}1%$ HOAc in 100% MeOH for 25 min, then 1% HOAc in 100% MeOH for 15 min, detector, ELSD, flow rate; 1ml/min. The mean contents of 1,2, and 3 in Poria cocos cultivated at 18 different site were $0.65{\pm}0.19,\;0.88{\pm}0.72,\;and\;0.84{\pm}0.54\;mg/g$, respectively, and values might be the guide line for the quality control of P. cocos.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.49-56
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• 2014

It is important to keep stable effluent water quality and minimize operation cost in biological wastewater treatment plant. However, the optimal operation is difficult because of the change of influent flow rate and concentrations, the nonlinear dynamics of microbiology growth rate and other environmental factors. Therefore, many wastewater treatment plants are operated for much more redundant oxygen or chemical dosing than the necessary. In this study, the optimal control scheme for dissolved oxygen (DO) is suggested to prevent over-aeration and the reduction of the electric cost in plant operation while maintaining the dissolved oxygen (DO) concentration for the metabolism of microorganisms in oxic reactor. For optimal control, The oxygen uptake rate (OUR) is realtime measured for the identification of influent characterization and the identification of microorganisms' oxygen requirement in oxic reactor. Optimal DO seT-Point needed for the microorganism is suggested based on real time measurement of oxygen uptake of microorganism and the control of air blower. Therefore, both stable effluent quality and minimization of electric cost are satisfied with a suggested optimal setpoint decision system by providing the necessary oxygen supply requirement to the microorganisms coping with the variations of influent loading.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.822-829
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• 2017

As a method to reduce the total phosphorus in sewage treatment plant, we applied the integral type slow mixing/sedimentation fiber filtration system to compare the control methods for the sewage effluent and the reject water. It was analyzed that about 92.4 kg T-P/day should be removed in order to satisfy the final concentration of phosphorus of 0.2 mg T-P/L, which is reinforced effluent standard. Therefore the total phosphorus removal efficiency should be 96% for sewage effluent and 69.2% for reject water (dehydrated filtrate) respectively. The system operation cost to achieve the target of total phosphorus removal efficiency was assessed. It has been found that the treatment cost of the reject water containing high concentration of phosphorus with a low flow rate is reduced to about 1/2.4 of the coagulant cost and about 1/120 of the electricity cost, compared to that of the sewage effluent treatment. Also the economics of the integral type slow mixing/sedimentation fiber filtration system and the general coagulation and sedimentation system were compared. It was evaluated that the development system was more economical because the installation area of the integral type slow mixing/sedimentation fiber filtration system was about 1/7 smaller than that of the general coagulation and sedimentation system, and the annual operation cost including the required amount of coagulant and electricity cost of the development system was lowered about 1/1.7 than that of the general system.