• Journal of the Korean Applied Science and Technology
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• v.25 no.1
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• pp.107-114
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• 2008

In this article a reliable and rapid method based on specific turbidimetry is proposed for the determination of sizes of nanoparticles. Conventionally in specific turbidimetry specific turbidities for a colloidal dispersion are measured as a function of light wavelength, and compared to theoretical values calculated from Mie scattering theory for presumed particle sizes. In contrast specific turbidity at a fixed wavelength is measured in the proposed method, and particle sizes are determined from the prepared calibration curve. The calibration curve is a plot of specific turbidity vs particle size and in this case the specific turbidities are measured for a couple of samples of known sizes.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.3
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• pp.237-243
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• 2016

Recently, technologies that produce biofuels from microalgae are being studied worldwide. It is necessary to significantly reduce the production costs of biofuels from microalgae for economic reasons. In this study, the growth curve of the microalgae was obtained using the batch-culture method, and the specific growth rate was predicted using the regression method. Based on the culture conditions of the estimated specific growth rate, the turbidity of the microalgae in the flat panel photobioreactor (PBR) was measured. Furthermore, an on-off control scheme was applied to the flat panel PBR in order to culture the microalgae continuously on the basis of turbidity. The parameters of the on-off control system were displayed by LabView. The on-off scheme of peristaltic pump was controlled based on the turbidity in the PBR. In addition, the turbidity values of growth curves were compared and analyzed in the continuous culture process using the on-off controller.

• Korean Journal of Food Science and Technology
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• v.32 no.6
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• pp.1319-1325
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• 2000

Antimicrobial effects of the specific IgY separated from eggs which were laid by hens vaccinated with Streptococcus mutans were investigated. The comparison tests of vaccination, addition levels of crude specific IgY, and innoculation concentration were applied by microscopic observation and turbidity test. Ten% addition of crude specific IgY obtained from vaccinated hens showed agglomerative clusters of S. mutans cells in supernatants and sediments, while crude IgY produced by non-vaccinated hens showed no cluster. IgY addition above 5% showed agglutinating clusters of most S. mutans cells and there was definite difference between IgY addition below 2.5% and above 5%. Concentration tests of crude IgY revealed that antimicrobial effects were differentiated by addition level and addition over 10% produced satisfactory results with turbidity test. The cluster size was dependent upon concentration of crude IgY addition. $10^5\;cfu/mL$ inoculation showed agglutinated cells and extent of agglomeration was proportional to cell numbers. Study of inoculation levels showed that 10% addition of crude IgY decreased turbidity effectively regardless of number of S. mutans cells. Plaque formation decreased to 75% with 15% addition of specific IgY concentration. These results implied that IgY separated from eggs laid by S. mutans-vaccinated hens might prevent dental caries caused by S. mutans.

• Science of Emotion and Sensibility
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• v.20 no.2
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• pp.3-10
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• 2017

This research investigated the cross-modal correspondence between the turbidity and taste of beverages. For an empirical study, we employed two types of achromatic beverages: rice wine and a soft drink. The turbidity of each drink varied between 0.0625~32 g/L, and 0.0078~4 g/L, respectively, and the stimuli were prepared in ten levels according to cognitive turbidity. In the study, participants (N=35) rated each drink stimulus using a 3-point Likert scale with regard to five basic tastes: sweet, salty, bitter, sour, and preferred. In addition, six specific tastes were included that deliberately describe rice wine and the soft drink. Three were yeasty, alcoholic, and astringent for the rice wine, and the other three were creamy, bubbly, and syrupy for the soft drink. Based on participants' assessments, the turbidity of rice wine is highly positively correlated with all five basic tastes. In contrast, the turbidity of the soft drink was positively correlated with sour only. Concerning preference, the most preferred turbidity of rice wine was 4.6~20 g/L, which is close to the turbidity of existing products on the market. Furthermore, except for astringent and syrupy, all tastes were influenced by the turbidity, which implies the potential of turbidity as a new visual parameter to communicate the taste experience of beverages.

• Membrane Journal
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• v.22 no.2
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• pp.135-141
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• 2012

This study was carried out to find the optimum coagulation conditions for ceramic microfiltration process of Y water treatment plant. When pH of raw water from Y Dam was adjusted to 7, the efficiency of coagulation was the best and the optimun dosage of coagulant was 3 mg/L(as $Al_2O_3$) for turbidity of raw water less then 10 NTU in Jar test. In mini module test, the decay rate of specific flux was the lowest when PAC (poly Aluminum Chloride) was used among coagulants and pH was adjusted to 7. The decay rate of specific flux for raw water turbidity of 10~30 NTU was greatly decreased with increase of dosage of coagulant (PAC) while the rate was not significantly decreased for turbidity more than 50 NTU. In conclusion, the optimum dosage of PAC (11% as $Al_2O_3$) was 30 and 50 mg/L for raw water turbidity of less than 10 NTU and more than 50 NTU, respectively. The dosage of PAC should be increased linearly 30 to 50 mg/L depending on raw water turbidity of 10 to 50 NTU.

• Journal of Korean Society on Water Environment
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• v.24 no.3
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• pp.365-377
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• 2008

Large artificial dam reservoirs and associated downstream ecosystems are under increased pressure from long-term negative impacts of turbid flood runoff. Despite various emerging issues of reservoir turbidity flow, turbidity modeling studies have been rare due to lack of experimental data that can support scientific interpretation. Modeling suspended sediment (SS) dynamics, and therefore turbidity ($C_T$), requires provision of constitutive relationships ($SS-C_T$) and accounting for deposition of different SS size fractions/types distribution in order to display this complicated dynamic behavior. This study explored the performance of a coupled two-dimensional (2D) hydrodynamic and particle dynamics model that simulates the fate and transport of a turbid density flow in a negatively buoyant density flow regime. Multiple groups of suspended sediment (SS), classified by the particle size and their site-specific $SS-C_T$ relationships, were used for the conversion between field measurements ($C_T$) and model state variables (SS). The 2D model showed, in overall, good performance in reproducing the reservoir thermal structure, flood propagation dynamics and the magnitude and distribution of turbidity in the stratified reservoir. Some significant errors were noticed in the transitional zone due to the inherent lateral averaging assumption of the 2D hydrodynamic model, and in the lacustrine zone possibly due to long-term decay of particulate organic matters induced during flood runoffs.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.934-944
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• 2007

Fine suspended solids (SS) induced into a reservoir after flood events play important ecological and water quality roles by presenting persistent turbidity and attenuating light. Thus the origin and physical features must be characterized to understand their transport processes and associated impacts, and for the establishment of watershed based prevention strategies. This study was aimed to characterize the physical properties of the SS sampled from Daecheong Reservoir and its upstream rivers during flood events. Extensive field and laboratory experiments were carried out to identify the turbidity-SS relationships, particle size distributions, settling velocity, and mineral compositions of the SS. Results showed that the turbidity-SS relationships are site-specific depending on the locations and flood events in the system. The turbidity measured within the reservoir was much greater than that measured in the upstream rivers for the same SS value. The effective diameters ($D_{50}$) in the rivers were in the range of $13.3{\sim}54.3{\mu}m$, while those in the reservoir were reduced to $2.5{\sim}14.0{\mu}m$ due to a fast settling of large particles in the rivers. The major minerals consisting of the SS were found to be Illite, Muscovite, Albite, and Quartz both in the rivers and reservoir. Their apparent settling velocities at various locations in the reservoir were in the range of 0.06~0.13 m/day. The research outcome provides a fundamental information for the fine suspended particles that cause persistent turbidity in the reservoir, and can be used as basic parameters for modeling study to search watershed based optimal control measures.

• Journal of Korea Water Resources Association
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• v.44 no.12
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• pp.991-1000
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• 2011

The relationship between discharge (Q) and suspended sediment (SS) concentration often is used for the estimation of inflow SS concentration in reservoir turbidity modeling in the absence of actual measurements. The power function, SS=aQb, is the most commonly used empirical relation to determine the SS load assuming the SS flux is controlled by variations of discharge. However, Q-SS relation typically is site specific and can vary depending on the season of the year. In addition, the relation sometimes shows hysteresis during rising limb and falling limb for an event hydrograph. The objective of this study was to examine the hysteresis of Q-SS relationships through continuous field measurements during flood events at inflow rivers of Yongdam Reservoir and Soyang Reservoir, and to analyze its effect on the bias of SS load estimation. The results confirmed that Q-SS relations display a high degree of scatter and clock-wise hysteresis during flood events, and higher SS concentrations were observed during rising limb than falling limb at the same discharge. The hysteresis caused significant bias and underestimation of SS loading to the reservoirs when the power function is used, which is important consideration in turbidity modeling for the reservoirs. As an alternative of Q-SS relation, turbidity-SS relation is suggested. The turbidity-SS relations showed less variations and dramatically reduced the bias with observed SS loading. Therefore, a real-time monitoring of inflow turbidity is necessary to better estimate of SS influx to the reservoirs and enhance the reliability of reservoir turbidity modeling.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.4
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• pp.486-492
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• 2004

CMP (Chemical mechanical polishing) is inevitable process to overcome $0.2{\mu}m$ wire thickness in semiconductor industry. In this study, effect of pressure to separate used CMP slurry into solid and liquid for recycle and reuse by ultrafiltration was investigated. Also, water quality after the ultrafiltration such as turbidity and TDS was evaluated. The material of membrane used in the study was PVDF. The used CMP contained 0.5% of solid content and then concentrated up to 18% by weight. The used CMP can not be concentrated higher than 18% because of viscosity and abrasion of pump. The tested feed pressures were 22.1, 29.4 and 36.8 psi. The results have shown that operating at 36.8 psi has advantages on operation time and total flux. The specific flux showed some variation at 1 to 15 of concentration factor but no difference after 15 of concentration factor. Mass balance of solid at initial stage of the operation showed some unbalance because of deposition of solid on the membrane, which was main reason to reduce flux. Turbidity was very stable at lower than 0.2NTU for 22.1 and 36.8 psi of feed pressure.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.1
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• pp.12-17
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• 2010

The oil tanker ship over 150GRT must equip oil content meter which satisfy requirements of revised MARPOL 73/78. Online measurement of oil content in complex samples is required to have fast response, continuous measurement, and satisfaction of ${\pm}10ppm$ or ${\pm}10%$ error in this field. The research of this paper is to develop oil content measurement system using analysis of light transmission and scattering among turbidity measurement methods. Light transmission and scattering are analytical methods commonly used in instrumentation for online turbidity measurement of oil in water. Gasoline is experimented as a sample and the oil content approximately ranged from 14ppm to 600ppm. TSK Fuzzy Model may be suitable to associate variously derived spectral signals with specific content of oil having various interfering factors. Proposed Parallel TSK Fuzzy Model is reasonably used to classify oil content in comparison with other models. Those measurement methods would be effectively applied and commercialized to oil content meter that is key components of oil discharge monitoring control equipment.