• Journal of Korea Water Resources Association
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• v.51 no.6
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• pp.535-542
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• 2018

The study was intended to simulate the sediment reduction effects of the Vegetative Filter Strip (VFS) in uplands of Saemangeum watershed through VFSMOD-W model application. The model was calibrated by using the field data and the simulation scenarios were designed based on the investigation of uplands characteristics in Saemangeum watershed. The simulation scenarios were considered various size and slope of uplands including 1 ha, 5 ha, 10 ha of field size with width-length ratio of 1 : 1 having 7% and 15% of slopes under the daily rainfall of 50 mm, 100 mm, 150 mm, and 200 mm in order to mimic the different fields conditions. The effluent reduction ranged from 2.9~13.5% and 2.9~12.1% for runoff, and 33.8~97.0% and 27.1~85.9% for sediment under the field's slope of 7% and 15%, respectively. The VFS reduction effects showed different degree of influence from field size, slope, rainfall amounts. Based on the simulated results, the sediment contributing non-point source pollution expected to be reduced in the condition of VFS constructed 10% of fields in outlet of less than 10 ha of uplands having less than 15% of the slope.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.623-626
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• 2005

This study is aimed for investigating the influence of the properties of crushed stone sand on the mixing factor and compressive strength of concrete. The results of this study are as follows; The influence of Particle Shape and Very Fine Sand(VFS) of crushed stone sand on the mixing factor was higher than Fineness Modulus. The demand water of concrete with crushed stone sand was decreased about $12\~18kg/m^3$with increasing $4\%$ of Particle Shape and increased $8\~15kg/m^3$ with increasing $3\%$ of ratio of Very Fine Sand(VFS).

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.499-503
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• 2008

In order to control the non-point source pollution, a vegetative filter strips (VFS) was set up and the site-monitoring was performed. The objective of this study is to investigate the influence of the plant coverage on treatment efficiency of total nitrogen (T-N) and total phosphorus (T-P) using vegetative filter strips. According to the results, it seemed that the treatment efficiencies of T-N and T-P were closely related with the plant coverage ratio. The results showed that treatment efficiency of T-P average 50% at higher than 50% of the plant coverage and 20~23% at lower than 50% of the plant coverage. Also, the treatment efficiency of T-N increased with the increase of the plant coverage ratio.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.2
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• pp.81-91
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• 2000

Dynamic models of line regulator valve(LRV) and ratio control valve (RCV) are obtained for an electronic controlled CVT. LRV and RCV are operated by variable force solenoid(VFS). Considering the CVT shift dynamics, oil pump's efficiency and saturation characteristics of VFS, simulations are performed and compared with test results. Simulation results are in good agreement with the experiments, which shows the validity of the dynamic models of LRV and RCV obtained. In addition, the effects of the orifice size in the exhaust port of RCV are investigated. Simulation results show that as the orifice size decreases, the residual pressure in the primary actuator increases which insures the large torque transmission capacity, meanwhile the duration time for the downshift increases.

• Korean Journal of Environmental Agriculture
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• v.37 no.3
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• pp.151-159
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• 2018

BACKGROUND: In this review paper, the effects of surface cover (SCV), vegetative filter strip (VFS), and vegetated ridge (VRD) on the pollutant runoff from steep-sloping uplands were analyzed to compare the pollutant reduction efficiency in runoff ($PRE_{runoff}$) of the practices and to investigate how slope and rainfall parameters affect the $PRE_{runoff}$. METHODS AND RESULTS: The $PRE_{runoff}$ of SCV, VFS, and VRD for pollutants including suspended solids and biological oxygen demand was compared by analysis of variance. The effect of slope and rainfall parameters on the $PRE_{runoff}$ was explored by either mean comparison or regression analysis. It was found that the $PRE_{runoff}$ differs with the practices due to different pollutant reduction mechanisms of the practices. Though the $PRE_{runoff}$ was likely to be affected by site condition such as slope and rainfall (amount and intensity), more comprehensive understanding was not possible due to the limited data set. CONCLUSION: The $PRE_{runoff}$ of SCV, VFS, and VRD differed due to the distinctive mechanisms of pollutant removal of the practices. It is necessary to accumulate experimental data across a variety of gradient of slope and rainfall for comprehensive understanding of the effects of the practices on pollutant runoff from steep-sloping uplands.

• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.375-383
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• 2012

Soil erosion has been emphasized as serious environmental problem affecting water quality in the receiving waterbodies. Recently, Best Management Practices (BMPs) have been applied at a field to reduce soil erosion and its effectiveness in soil erosion reduction has been monitored with various methods. Although monitoring at fields/watershed outlets would be accurate way for these ends, it is not possible at some fields/watersheds due to various limitations in direct monitoring. Thus modeling has been suggested as an alternative way to evaluate effects of the BMPs. Most models, which have been used in evaluating hydrology and water quality at a watershed, could not reflect rainfall intensity in runoff generation and soil erosion processes. In addition, source codes of these models are not always public for modification/enhancement. Thus, runoff-sediment evaluation system using hourly rainfall data and vegetated filter strip (VFS) evaluation module at field level were developed using open source MapWindow GIS component in this study. This evaluation system was applied to Bangdongri, Chuncheonsi to evaluate its prediction ability and VFS module in this study. The NSE and $R^2$ values for runoff estimation were 0.86 and 0.91, respectively, and measured and simulated sediment yield were 15.2 kg and 16.5 kg indicating this system, developed in this study, can be used to simulate runoff and sediment yield with acceptable accuracies. Nine VFS scenarios were evaluated for effectiveness of soil erosion reduction. Reduction efficiency of the VFS was high when sediment inflow was small. As shown in this study, this evaluation system can be used for evaluation BMPs with local rainfall intensity and variations considered with ease-of-use GIS interface.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.1-7
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• 2004

Increase of internet users and new type of applied traffic such as game, news, distributed computing, online image conference, and real time audio and video have leaded to demand for more bandwidth for each application. This algorithm represents a complex optical exchanger having typical wavelength switching function and time-slotted transmission function. Performance assessment of the proposed OXC (Optical Cross connect) sttucture defines LFS (Limit Frame Size) and VFS (Variable Frame Size) for classification by packet type and calculates the channel effect and loss probability depending the demanded bandwidth by access node increase. Optical exchanger in this type of structure can guarantee future network expansion as well as decrease of frame collision resulted from node increase.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.417-420
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• 2002

Non-point source pollution of sediment, plant nutrients and pesticides from cropland has been identified as a significant environmental problem. Vegetative Filter Strips have been identified as one of BMPs to control nonpoint source pollution. This paper reviews the concept, functions, design criteria and management of VFS to control nonpoint source pollution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.678-685
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• 2016

Deglutition inspection has been the gold standard for inspection of dysphagia using a penetration device of the division of radiology to date. However, inspection using an endoscope has facilitated diagnosis of dysphagia in recent days. In this study, we compared the results of VFSS alone with those of VFSS combined with FEES to determine if the detection rate of penetration, aspiration, and pharyngeal residue increased. This study evaluated at 130 persons who underwent both VFSS and FEES from December 2013 through March 2014, and used VFSS (FELAVISION, SHIMADZU) and FESS (EVIU LUCERA CV-260SL, OLYMPUS) as devices. After preparing barium diluted solution, yogurt that diluted barium and rice that diluted barium in 2.5 ml, 5 ml, 10 ml by modifying Logemann's protocol in part, and having subjects take the solution, this study confirmed pharyngeal residue, penetration, aspiration etc. VFFS and FEES using full HD video revealed aspiration in 36 of the 130 patients in both inspections. Additionally, aspiration was discovered in 36 patients upon VFFS, but in 41 upon FESS. Although FEES was more sensitive at diagnosing dysphagia, the two inspection methods are complementary, so diagnostic value will be greatly improved when the endoscope operating method and accurate fluoroscopic inspection are combined.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.3
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• pp.205-212
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• 2000

Experimental investigations on the removal of protein, total suspended solids and turbidity from aquacultural water were carried out by using three types of foam separator: counter current air driven type foam separator (CCADFS), high speed aeration type foam separator (HSAFS) and venturi type foam separator (VFS). The decrease of flow rate by CCADFS, HSAFS and VFS were $0.4,\;66.1,\;77.2 {\%}$ respectively. Protein removal rates by three types foam separator were decreased with the increased hydraulic residence time (HRT). Bellw 0.32 minute and 0.21 minute of hydraulic residence times, protein removal rate of HSAFS and YES was higher than that of CCADFS, respectively. Protein removal rate of VFS was lower than that of HSAFS at any HRT. As increasing the HRT, protein removal efficiency of CCADFS was increased, but that of HSAFS and VES were decreased. The changes of removal rates and efficiencies of total suspended solid and turbidity were similar to proteins.