• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.87-87
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• 2019

흔히 진흙으로 대표되는 점착성 유사는 모래와 같은 비점착성 유사와 달리 응집 현상으로 인해 지속적으로 유사 입자의 크기가 변화한다. 응집 현상은 점착성 유사 입자의 응집 과정과 파괴과정으로 구성된다. 응집 현상 중 응집 과정은 유사 입자 간의 충돌로 인해 발생하는 것으로 이해되며, 충돌을 야기하는 메커니즘으로는 브라운 운동(Brownian Motion), 차등침강(Differential Settling), 난류 전단 (Turbulent Flow Shear)이 있다. 파괴 과정은 입자간 충돌로 인해 깨지는 것이 아닌 난류 전단(Turbulent Shear)로 인한 덩어리 분리(Massive Splitting)가 발생하는 것으로 이해한다. 이러한 유체의 특성, 흐름 특성 (난류 거동) 뿐만 아니라 유사 입자의 특성 모두의 영향을 받으며 지속적인 응집 현상을 겪는 점착성 유사 입자들은 하나의 커다란 덩어리인 플럭(Floc)을 형성한다. 형성된 플럭의 구조는 프랙탈 기하학을 따르는 것으로 이해된다. 따라서 플럭의 구조는 자기 유사성을 띠며, 플럭의 밀도는 형성된 플럭 크기의 함수가 된다. 플럭의 크기가 증가할수록 플럭의 프랙탈 차원이 감소하며, 플럭의 밀도는 감소한다. 많은 이전의 연구에서 플럭의 침강 속도를 농도에 따른 함수로 가정하고 경험식을 이용하여 산정하나, 유사 입자의 침강 속도는 크기와 밀도의 함수임을 Stokes Law를 통해 생각해 볼 수 있다. 이에 본 연구에서는 응집 현상의 결과물로 형성된 응집물의 크기와 밀도를 각각 산정하고, Stokes Law를 이용하여 침강 속도와 응집물 크기의 관계에 대한 연구를 수행하고자 한다. 보다 심도 있는 연구를 위해서는 응집 현상을 야기하는 메커니즘에 대한 이해가 필수적이다. 간소화된 응집 모형으로부터 얻어진 플럭 크기를 이용하여 프랙탈 차원, 플럭의 밀도를 산정한다. 형성된 응집물의 크기와 침강 속도의 관계에 대한 이해를 통해 보다 정확한 플럭의 침강 속도 산정이 가능할 것으로 생각된다.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.826-831
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• 2018

This study presents fabrication of bi-compartmental particles labeled by multiple fluorescence. To compartmentalize fluorescent expression at the particle, two fluorescent dyes with less overlap of the excitation and emission spectra are selected. To ensure the fluorescence stability, the fluorescent dyes contain acrylate functional groups in the molecules so that they can be cross-linked together with monomers constituting the particle. Strong fluorescent expression and compartmentalization were observed at the particle fabricated using the selected fluorescent dyes through confocal microscopy. Furthermore, long-term fluorescence stability was verified by measuring fluorescent expression and intensity for 4 weeks. We anticipate that the bi-compartmental particles labeled by multiple fluorescence can be widely used for multi-target drug delivery system, analysis of 3 dimensional Brownian motion, and investigation of 3 dimensional complex self-assembled morphologies.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.84-89
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• 2020

Particulate matters of PM_2.5, particularly focusing on 0.1~1 ㎛ decrease the efficiency of dust-collector due to the brownian-motion. This study is to verify the effect of coagulant on the particle size distributions of potassium and PM_2.5. The activated coagulant was spayed to the coal fired fluidized bed combustion boiler by the weight ratio of 1,200 : 1 = coal : coagulant, and the size distributions of captured particles at both the cyclone (FP) and electrostatic precipitator (EP) were measured. As the result of XRP analysis, the potassium content of FP increased to 13.33% (averagely from 1.65% to 1.87%) and, in EP at 17.68% (averagely from 1.65% to 2.03%). And it was confirmed by the particle size distribution analyzer and SEM image analysis that the distribution rates of PM_2.5 decreased at 89.53% on average in FP, and at 88.57% in EP. The total dust concentration (mg/㎥) confirmed by tele-monitering system (TMS) decreased during the primary test from 2.6 to 1.7~1.9 and also the secondary test from 2.9 to 1.7~1.9.

• KDI Journal of Economic Policy
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• v.35 no.4
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• pp.31-61
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• 2013

The purpose of this study is to calculate the economic value of transport demand forecasting risks in the road PPP project. Under the assumption that volatility of the road PPP project value occurs only in regard with uncertainty of traffic volume forecasting, this study calculates the economic value of the traffic forecasting risks in the case of the road PPP project. To that end, forecasted traffic volume is assumed to be a stochastic variable and to follow the Geometric Brownian motion as time passes. In particular, this study attempts to differentiate itself from existing studies that simply use an arbitrary assumption by presenting the application of different traffic volume growth volatility and the rates before and after the ramp-up period. Analysis of the case projects reveals that the risk premium related to traffic volume forecast of the project turns out as 7.39~8.30%, without considering option value-such as minimum revenue guarantee-while the project value volatility caused by transport demand forecasting risks is 17.11%. As the discount rate grows higher, the project value volatility tends to decrease and volatility in project value is always suggested to be larger than that in transport volume influenced by leverage effect due to fixed expenditure. The market value of transport demand forecasting risk-calculated using the project value volatility and risk premium-is analyzed to be between 0.42~0.50, implying that a 1% increase or decrease in the transport amount volatility would lead to a 0.42~0.50% increase or decrease in risk premium of the project.

• Journal of the Korean association of regional geographers
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• v.11 no.6
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• pp.530-542
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• 2005

In this study, GIS method has been used to get fractal characteristics. Using the projected area and surface area, 2 dimensional fractal characteristic of terrain was found out. Correlation of fractal dimension and mean slope were also checked over. Results are as below. 1) To get a fractal dimension, the method which is using the surface area is also directly proportional to complexity of the terrain as other fractal dimension. 2) Fractal dimensions using the surface area, that is proposed in this thesis are carried out as below : Uiseong : $2.02{\sim}2.15$ Yeongcheon : $2.10{\sim}2.24$. These values are in a range of fractal $2.10{\sim}2.20$ dimensions which has known. 3) Correlation of mean slope and fractal dimension is diminished about 30% in a region which is more than $25^{\circ}$ of mean slope. So, in this region using the fractal dimension method is better than using the mean slope. From this study, on formula using the projected area and surface area is still good to get a fractal dimension that has been found. But to confirm this method the region of research should be wider and be set up the correlation of mean slope, surface area and fractal dimension. It can be applicable to restoration of terrain and traffic flow analysis in the future research.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.506-512
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• 2018

The fine dust generated in the home and restaurant business occupies a low ratio of about 4% of the total fine dust emissions. However, at the foodservice business, the rate of change of the pollutant concentration is very high, so that the temporary fine dust concentration can be measured up to 60 times. The pollutants generated from non-industrial combustion plants consist of particulate fine dust and gaseous organic compounds. To remove these pollutants, cleaning dust collection system, which is an effective system for simultaneous removal of gaseous and particulate matter, is applied. This is a method of increasing the probability of diffusion capture of the Brownian motion by pressurized liquid injection method using the atomizing nozzle. The dust removal efficiency of the fine dust collecting system was analyzed by nozzle spraying air pressure condition and angle using the manufactured fine dust removing system. As a result, it was confirmed that the efficiency of removal of fine dust and gaseous organic compounds was more than 90%. The developed system is expected to be highly usable in the future because it can remove particulate dust from the existing plant hood system without any installation cost.