• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1201-1204
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• 2004

This paper suggests a DCS (Distributed Control System) model for steam temperature system of the thermal power plant. The model calculated within sectional range is linear. In order to calculate mathematical models, the system is partitioned into two or three sectors according to its thermal conditions, that is, saturated water/steam and superheating state. It is divided into three sections; water supply, steam generation and steam heating loop. The steam heating loop is called 'superheater' or steam temperature system. Water spray supply is the control input. A first order linear model is extracted. For linear approach, sectional linearization is achieved. Modeling methodology is a decomposition-synthetic technique. Superheater is composed of several tube-blocks. For this block, linear input-output model is to be calculated. Each tiny model has its transfer function. By expanding these block models to total system, synthetic DCS linear models are derived. Control instrument include/exclude models are also considered. The resultant models include thermal combustion conditions, and applicable to practical plant engineering field.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.4
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• pp.28-35
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• 1997

Sole-binder formulation has been recently introduced to solve the problems of coating process and printability caused by use of natural polymer However, the decrease of natural polymer application causes another problem in paper coating. Therefore, synthetic thickener is used to get similar effect to natural polymer usage. In this study. low shear viscosity, dewatering of coating colors were measured to evaluate the performance of the alkali sensitive water retention and rheology modifiers. The effects of alkali sensitive thickener on the physical properties of coated paper and printability were also investigated. The gloss and printability of coated paper containing the synthetic flow modifier were similar or superior to those of CMC containing coated paper. This modifier was also effective to improve the problems caused by the use of starch. The results indicated that the flow modifier synthesized with alkali sensitive thickener can reduce the problems of natural polymer and could be a good substitute f3r a natural polymer.

• Journal of Environmental Health Sciences
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• v.19 no.1
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• pp.77-89
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• 1993

Effects of fermented milk were tested in Sprague-Dawley male rats. In six treatment 150 rats were fed for 12 months: (1) normal control synthetic pellets+water, (2) cholesterol control synthetic pellets containing 1% of cholesterol and 500, 000 IU of vitamin D2/100 g (cholesterol pellets) +water, (3) cholesterol pellets+25% fermented milk, (4) cholesterol pellets+50% fermented milk, (5) cholesterol pellets+75% fermented milk, (6) cholesterol pellets+100% fermented milk. In 3, 6, 9, 12 months, rats were sacrificed for analysis of samples. Rats received the fermented milk had significantly lower (p<0.05) serum cholesterol levels and higher ratios of HDL-cholesterol to total cholesterol than did the water fed rats. Stomach, heart, abdominal aorta and kidney of rat from fermented milk group showed slighter calcification or necrosis than did those of rat from cholesterol control group. Weight gain, diet intake, and drink consumption were significantly different among groups. Results indicate that fermented milk had a helpful effect of experimental hypercholesteremia and atherosclerosis.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.3
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• pp.8-13
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• 2015

This study investigates the application of a synthetic resine based net-hose system to sustain vegetated embankment slope reinforcement. The net-hose system is designated to improve water supply to the vegetation that can suffer the lack of water in case of extreme drying condition or rock slope where water supply is relatively insufficient to ensure the growth of vegetation. A series of laboratory tests were conducted to check the structural adequacy and effectiveness of net-hose system. The results indicated that the model slope equipped with net-hose system seemed to provide better water supply resulting in more vegetated areas and higher matric suction due to active water uptake capacity, which might be contributed to greater shear strength of slope surface. A limited numerical analysis was conducted to verify the effect of water uptake on vegetated root system that generally yields better slope stability.

• Journal of Korean Society on Water Environment
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• v.32 no.6
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• pp.537-545
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• 2016

In order to cope with the new and strict government regulations for turbid water discharge from construction sites, this study tested whether synthetic fiber filters can replace conventional best management practices. The filter efficiency was about 10 to 60% with a varying filter depth of 5 to 15cm, presuming extreme storm flow conditions to be in the range of 800 to 1500m/day of filtration rates. Fiber filter acts exactly like a granular filter, i.e. the separation efficiency is directly and inversely proportional to filter depth and rate, respectively. Based on the operational data, we suggested the Log-Log design relationship, which can be used to determine the filter depth and area. Compared to the widely used gravel filter which treats the turbid water at the construction site, about 20% higher efficiency was obtained under similar operating conditions. Cleaning the filter through a simple hand-washing method at the time of break-through, achieved about 90% soil recovery.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.6
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• pp.387-395
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• 2014

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/tandem mass spectrometry (GC-MS/MS) has been developed, allowing the simultaneous multi-analyte determination of 11 synthetic fragrances (SFs) in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 10.9%). The extraction efficiencies were above 83% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1~4.1 ng/L and 6.6~12.9 ng/L, respectively. The developed method offers the ability to detect 11 SFs at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 11 SFs. The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.

• Water Engineering Research
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• v.2 no.4
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• pp.219-229
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• 2001

Synthetic unit hydrograph equations for rainfall run-off characteristics analysis and estimation of design flood have long and quite frequently been presented, the Snyder and SCS synthetic unit hydrograph. The major inputs to the Snyder and SCS synthetic unit hydrograph are lag time and peak coefficient. In this study, the methods for estimating lag time and peak coefficient for small watersheds proposed by Zhao and McEnroe(1999) were applied to the Kum river basin in Korea. We investigated lag times of relatively small watersheds in the Kum river basin in Korea. For this investigation the recent rainfall and stream flow data for 10 relatively small watersheds with drainage areas ranging from 134 to 902 square kilometers were gathered and used. 250 flood flow events were identified along the way, and the lag time for the flood events was determined by using the rainfall and stream flow data. Lag time is closely related with the basin characteristics of a given drainage area such as channel length, channel slope, and drainage area. A regression analysis was conducted to relate lag time to the watershed characteristics. The resulting regression model is as shown below: ※ see full text (equations) In the model, Tlag is the lag time in hours, Lc is the length of the main river in kilometers and Se is the equivalent channel slope of the main channel. The coefficient of determinations (r$^2$)expressed in the regression equation is 0.846. The peak coefficient is not correlated significantly with any of the watershed characteristics. We recommend a peak coefficient of 0.60 as input to the Snyder unit-hydrograph model for the ungauged Kum river watersheds

• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.3
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• pp.4739-4749
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• 1978

This studies were conducted to derive synthetic unitgraphs and triangular unitgraphs correlated with watershed characteristics which can be used to the estimation and control of flood for the rational development of Agricultural water resources. Derived Synthetic unitgraphs and Triangular unitgraphs can be applied to the ungaged watersheds were compared with average unitgraphs by observed data. Seven small watersheds were selected as studying basins Han, Geum, Nakdong, Yeongsan and Inchon river system. The results summarized for these studies are as follows: 1. Average unitgraphs by observed data and dimensionless unitgraphs for synthesis were derived for all river systems. 2. Peak discharge per unit area of the unitgraph, qp, was derived as qp=10-0.389-0.0424Lg with a high significance. 3. Formulas for the base width of unitgraph of 50 and 75 percent for peak flow for each water systems was adopted as Table 5. 4. The base length of the unitgraph, Tb, in hours in connection with time to peak, Tp, in hours was expressed as Tb =4.3Tp. 5. Peak discharge, Qp, were obtained as Table 6 by the Triangular form to all subwatersheds. 6. Relative errors in the peak discharge of the synthetic unitgraphs showed to be 7.3 percent to the peak of observed average unitgraphs except errors of peak discharge for Yeongsan river system. This indicates that Synthetic unitgraphs for the small watersheds of Han, Geum, Nakdong and Inchon river systems can be applied to the ungaged watersheds. On the other hand, It was confirmed that the accuracy of Instantaneous Unit Hydrograph with only 1.6 percent as relative errors was approaching more closely to the observed average unitgraph than that of synthetic unitgraph with relative errors. 23.9 percent for Yeongsan river system. 7. Errors in the peak discharge of the triangular unitgraph to the observed average unitgraph showed to be 0.6 percent to 7.5 percent which can be regarded as a high precision within the range of 200 to 500$\textrm{km}^2$ in area. On the contrary, application of triangular unitgraph within the range of 200$\textrm{km}^2$ in area has defined as a unsuitable method because of high relative errors, 26.4 percent to 61.6 percent.

• Journal of Korea Water Resources Association
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• v.32 no.3
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• pp.291-300
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• 1999

The Snyder's synthetic unit hydrograph method is selected to apply the concept of the fractal dimension by stream order for the practicable rainfall-runoff generation, and fourth types of the Snyder's relation are derived from topographic and observed unit hydrograph data of twenty-nine basins. As a result of the analysis of twenty-nine basins and the verification of two basins, the Snyder's relation which considers the fractal dimension of the stream length and uses calculated unit hydrograph data shows the best result. The concept of the fractal dimension by stream order is applied to the Snyder's synthetic unit hydrograph method. The topographic factors, used in the Snyder's synthetic unit hydrograph method, which have a property of the stream length like $L_{ma}$ (mainstream length) and $L_{ca}$ (length along the mainstream to a point nearest the watershed centroid) were considered. In order to simplify the fractal property of stream length, it is supposed that $L_{ma}$ has not the fractal dimension and the stream length between $L_{ma}$ and ($L_{ma}\;-\;L_{ca}$) has the fractal dimension of 1.027. From the utilization of this supposition, a new Snyder's relation which consider the fractal dimension of the stream length occurred by the map scale used was finally suggested.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.10
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• pp.888-893
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• 2016

In this study, the solution plasma process was utilized with the aim of degrading synthetic dyes in water at atmospheric pressure. The experiments were conducted in a batch-type reactor consisting of a symmetric wire-wire electrode configuration with rhodamine B (RhB) as the target synthetic dye. The effects of the plasma treatment time and initial dye concentration on the RhB degradation were investigated by monitoring the change in absorbance of RhB solutions. The RhB solutions turned lighter in color and finally colorless with prolonged plasma treatment time, indicating the destruction of dye molecules. The RhB solutions were found to have degraded, following the first-order kinetic process. However, for high initial RhB concentrations, another kinetic process or factor seems to play a dominant role at the initial degradation stage. The fitted first-order rate constant decreased as the initial concentration increased. This result suggests that the degradation behavior and kinetic process of the RhB solution strongly depends on its initial concentration. The RhB degradation is considered to be due to a combination of factors, including the formation of chemically oxidative species, as well as the emission of intense UV radiation and high-energy electrons from the plasma. We believe that the solution plasma process may prove to be an effective and environment-friendly method for the degradation or remediation of synthetic dye in wastewater.