• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.179-184
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• 2001

The mechanism of the aerosol generation consists of spin-off, splash, and evaporation/condensation. Most researchers showed some theoretical model for predicting the particulate size and generation rate without cutting in turning operation. These models were based on the spin-off mechanism and verified good for modeling the process. However, in real machining, the cutting tool destructs the spin-off process, and the majority of the mist is due to splash. In this paper, we show some experimental evidence the aerosol generation mechanism should be explained with splash model as well as spin-off.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.93-99
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• 2002

The mechanism of the aerosol generation generally consists of spin-off, splash, and evaporation/condensation. Most researchers showed some theoretical model for predicting the particulate size and generation rate without real cutting in turning operation. These models were based on the spin-off mechanism, and verified good for modeling the process. However, in real machining, the cutting tool destroys the spin-off process, and the majority of the mist is due to splash. In this paper, we show some experimental evidence that the aerosol generation mechanism in real machining should be explained with splash model as well as spin-off.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.147-152
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• 2002

The mechanism of the aerosol(mist) generation generally consists of spin-off, splash, and evaporation/condensation. Host researchers showed some theoretical model for predicting the particulate size and generation rate without real cutting in turning operation. These models were based on the spin-off mechanism, and verified good for modeling the process. However, in real machining, the cutting tool destroys the flow direction of the cutting fluid and generate the heat by the relative motion of between tool and workpicee, and so the mass loading of the mist is greatly increased as compared with non-cutting. In this paper, we show some experimental data that the mist formation characteristics of cutting is different from that of non-cutting.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.620-625
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• 2018

Liquid detergent based on sodium lauryl ethoxy sulfate (SLES) as main ingredient sometimes met gelling film on the surface when it is opened in the air. It was assumed because of the change of phase diagram of micelle by concentration change of surfactant, major ingredient of detergent when the water of detergent is evaporated. SLES showed strong hexagonal liquid crystal (LC) in 30~60 wt%, and lamellar LC over 60 wt%. In this research surface gelling formation of liquid detergent which is based on SLES as main ingredient was because of water evaporation. As water of detergent was evaporated, concentration of surfactant became higher. It was checked that surface gelling was LC of mixed surfactant system. Conclusionally we applied alpha olefin sulfonate (AOS) having good solubility, Sodium secondary alkane sulfonate (SAS) preventing hexagonal LC and hydrotrope sodium xylene sulfonate (SXS) and PEG1500 in order to prevent gelling film in SLES based liquid detergent. Like this, improved formula 4 and 5 can prevent the formation of gelling film on the surface of liquid detergent when it is opened in the air.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.2
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• pp.147-154
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• 2014

In this study, chlorine modeling technique based on fuzzy system is proposed to reduce the carcinogenic substance and decide the optimal chlorine injection rate, which is affected by chlorine evaporation rate in sedimentation basin according to detention time, weather and water quality. The additional chlorine meter is installed in the inlet part of sedimentation to reduce the feedback time and implement cascade control, which leads to maintaining the residual chlorine concentration decided by fuzzy rule. It helps to take a preemptive action about long time delay, the characteristics of the disinfection process, and reduce the variation of residual chlorine rate by 7.3 times and the chlorine consumption by 40,000 dollars. It made a significant contribution to supply hygienically safe drinking water.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.247-247
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• 2023

Coastal lagoons play a crucial role in water exchange, water quality, and biodiversity. It is essential to monitor and understand the dynamics of hydrogeochemistry in lagoon water and its groundwater to preserve and sustainably manage the groundwater-dependent ecosystems like coastal lagoons. This study investigated the spatial and temporal hydrogeochemical characteristics of coastal lagoon (Songjiho) and groundwater on the east coast of Korea. The concentrations of major ions, water isotopes, and nutrients (nitrogen and dissolved organic carbon) in lagoon water and groundwater were periodically monitored for one year. The study revealed that major ions and total dissolved solids (TDS) concentration were higher at deeper depths of aquifers and closer to the coastal area. The hydrogeochemical characteristics of coastal lagoon and groundwater chemistry were classified into two types, Ca-Mg-HCO₃ and Na-Cl, based on their spatial location from inland to coastal area. Moreover, the hydrogeochemical characteristics of coastal lagoons and groundwater varied significantly depending on the season. During the wet season, the increased precipitation and evaporation lead to changes in water chemistry. As a result, the total organic carbon (TOC) of coastal lagoons increases during this season, likely due to increased runoff by rainfall whereas the variation of chemical compositions in the lagoon and groundwater were not significant because there is reduced precipitation, resulting in stable water levels and during the dry season. The study emphasizes the impact of spatial distribution and seasonal changes in precipitation, evaporation, and river discharge on the hydrogeochemical characteristics of the coastal aquifer and lagoon system. Understanding these impacts is crucial for managing and protecting coastal lagoons and groundwater resources.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.70-75
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• 1997

An improved technique based upon an electron beam evaporation system has been developed to prepare cubic thin films In crystalline semiconductors. Zinc blonde CdSe epilayers were grown on GaAs(100) substrate by an e-beam evaporation method. The lattice parameter obtained from (400) reflection is $6.077\AA$, which is in excellent agreement with the value reported in the literature for zinc blonde CdSe. The orientation of the as-grown CdSe epilayer is determined by electron channeling patterns. The crystallinity of epitaxial CdSe layers were investigated on the double crystal X-ray rocking curve. The carrier concentration and mobility of epilayers deduced by Hall effect measurement are about $10^{18}{\textrm}{cm}^{-3}$, $10^2\textrm{cm}^2/V{\cdot}sec$ at room temperature, respectively. The photocurrent spectrum peak of the epilayer at 30 K exhibits a sharp change at 1.746 eV due to the free exciton of cubic CdSe.

• Korean Journal of Microbiology
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• v.42 no.4
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• pp.286-293
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• 2006

Three hundred thirty two bacterial colonies which were able to degrade crude oil were isolated from soil samples that were contaminated with oil in Daejon area. Among them, one bacterial strain was selected for this study based on its low surface tension ability, and this selected bacterial strain was identified as Pseudomonas sp. G314 through physiological-biochemical tests and analysis of its 16S rRNA sequence. Pseudomonas sp. G314 showed a high resistance to antibiotics such as ampicillin, chloramphenicol, spectinomycin, and streptomycin, and heavy metals such as Li, Cr, and Mn. It was found that the optimal pH and temperature for biosurfactant production of Pseudomonas sp. G314 were pH 7.0 and $30^{\circ}C$, respectively. After seven hours of inoculated, the biosurfactant activity reached the maximum, and surface tension of the culture broth was decreased from 72 to 25 dyne/cm. The crude biosurfactant was obtained from the culture broth by acid precipitation, followed by solvent extraction, evaporation and then freeze drying. The CMC (critical micelle concentration) value of the crude biosurfactant was 20 mg/L.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.1
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• pp.69-75
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• 2003

In this study, his technique was applied to a GDI spray in order to investigate the mixture distribution. In addition, the homogeneity degree and diffusion effect according to ambient temperature in the high pressure chamber were analyzed by using an entropy analysis method. From this experiment, we could find that entropy analysis is very effective method for the analysis of mixture formation, and the entropy values increase with the progress of uniformity in diffusion Process. we tried to provide the fundamental data for parameter which effects on the spray macroscopic characteristics with mixture ratio of diesel and gasoline. In addition, the mixture formation was analyzed by using entropy analysis. The entropy analysis is based on the concept of statistical entropy, and it identifies the degree of homogeneity in the fuel concentration. From the entropy analysis results we could find that the direct diffusion phenomena is a dominant factor in the formation of a homogeneous mixture at downstream of GDI spray especially in vaporizing conditions. As to increasing ambient temperature and increasing gasoline rate, the entropy intensity using the statistic thermodynamics method is increased because evaporation rate is higher gasoline than diesel.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.215-219
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• 2005

A macro spreadsheet model, WEANES (Wet Pond Annual Efficiency Simulation Model), has been developed to predict the long-term or annual removal efficiencies of wet retention/detention basins. The model uses historical, site-specific, multi-year, rainfall data, usually available from a nearby National Oceanic and Atmospheric Administration (NOAA) climatological station to estimate basin efficiencies which are calculated based on annual mass loads. Other required input parameters are: 1) watershed parameters; drainage area, pervious curve number, directly connected impervious area, and ti me of concentration, 2) pond parameters; control and overflow elevations, pond side slopes, surface areas at control elevation and pond bottom; 3) outlet structure parameters; 4) pollutant event mean concentrations; and 5) pond loss rate which is defined as the net loss due to evaporation, infiltration and water reuse. The model offers default options for parameters such as pollutant event mean concentrations and pond loss rate. The model can serve as a design, planning, and permitting tool for consulting engineers, planners and government regulators.