• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.677-683
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• 2005

In this work, the effect of additives such as solvent, sodium dodecyl sulfate and NaCl on microemulsion phase behavior and flux removal efficiency in systems containing commercial alkyl ethoxylates nonionic surfactant was investigated. The addition of a n-hydrocarbon as a solvent produced on O/W (Oil/Water) microemulsion phase over a wider range of temperature and cosurfactant to surfactant ratios. Especially, the addition of n-hexadecane to the surfactant system, which was the most hydrophobic solvent among the solvents used in this study, produced a microemulsion phase over a wide range of temperatures and promoted formation of a microemulsion phase at lower temperatures. The candidate for cleaner samples, prepared from phase behavior experiments, showed excellent removal efficiency for abietic acid at $40^{\circ}C$. These data suggested the potential applicability of hydrocarbons to actual cleaner formulations.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.251-251
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• 2016

For several decades, industrial processes consume a huge amount of raw water for various objects that consequently results in the generation of large amounts of wastewater. Wastewaters are consisting of complex mixture of different inorganic and organic compounds and some of them can be toxic, hazardous and hard to degrade. These effluents are mainly treated by conventional technologies such are aerobic and anaerobic treatment and chemical coagulation. But, these processes are not suitable for eliminating all hazardous chemical compounds form wastewater and generate a large amount of toxic sludge. Therefore, other processes have been studied and applied together with these techniques to enhance purification results. These include photocatalysis, absorption, advanced oxidation processes, and ozonation, but also have their own drawbacks. In recent years, electrochemical techniques have received attention as wastewater treatment process that could be show higher purification results. Among them, boron doped diamond (BDD) attract attention as electrochemical electrode due to good chemical and electrochemical stability, long lifetime and wide potential window that necessary properties for anode electrode. So, there are many researches about high quality BDD on Nb, Ta, W and Si substrates, but, their application in effluents treatment is not suitable due to high cost of metal and low conductivity of Si. To solve these problems, Ti has been candidate as substrate in consideration of cost and property. But there are adhesion issues that must be overcome to apply Ti as BDD substrate. Al, Cu, Ti and Nb thin films were deposited on Ti substrate to improve adhesion between substrate and BDD thin film. In this paper, BDD films were deposited by hot filament chemical vapor deposition (HF-CVD) method. Prior to deposition, cleaning processes were conducted in acetone, ethanol, and isopropyl alcohol (IPA) using sonification machine for 7 min, respectively. And metal layer with the thickness of 200 nm were deposited by DC magnetron sputtering (DCMS). To analyze microstructure X-ray diffraction (XRD, Bruker gads) and field emission scanning electron microscopy (FE-SEM, Hitachi) were used. It is confirmed that metal layer was effective to adhesion property and improved electrode property. Electrochemical measurements were carried out in a three electrode electrochemical cell containing a 0.5 % H2SO4 in deionized water. As a result, it is confirmed that metal inter layer heavily effect on BDD property by improving adhesion property due to suppressing formation of titanium carbide.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.760-769
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• 1993

Solvent-free low foaming scouring agents(LFSA) were prepared by blending of polyoxyethylene(30) octadecylbenzylammonium chloride(POAC), block copolymer of propylene oxide-ethylene oxide[p(PO-b-EO) glycol], Sedlan FF-200(FF-200) and sulfonic acid-amine condensate of polyoxyethylene(10) nonylphenyl ether(PSAC). In consequence of several tests, FF-200/POAC/p(PO-b-EO) glycol/PSAC/water (20g/10g/5g/5g/60g) mixture (LFSA-5) showed good cleaning power, penetrating ability, emulsifiability and stability to alkali, and gave less problem in water pollution. Scouring effect of LFSA-5 was investigated by the change of percentage of exhaustion before and after scouring at various dyeing temperatures. The percentage of exhaustion of the unscoured PET fabric was 4.5% at $70^{\circ}C$, while that scoured with LFSA-5 was 1.3% at the same temperature, which proved LFSA-5 to be a good scouring agent. Moreover, the foaming power of LFSA-5 measured by Ross and Miles method was 6mm foam height immediately after foaming, and that measured by Ross and Clark method was less than 300mm foam height at $30^{\circ}C$, and 20mm at $80^{\circ}C$. As a result, LFSA-5 proved a good low foaming scouring agent.

• Journal of Environmental Science International
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• v.25 no.8
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• pp.1065-1076
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• 2016

This study analyzes the $PM_{10}$ characteristics (particulate matter with aerodynamic diameter less than $10{\mu}m$), concentration, and emissions in eight large South Korean cities (Seoul, Incheon, Daejeon, Daegu, Gwangju, Ulsan, Busan, Jeju). The annual median of $PM_{10}$ concentration showed a decline of $0.02{\sim}1.97{\mu}g/m^3$ in the regions, except for Incheon, which recorded an annual $0.02{\mu}g/m^3$ increase. The monthly distribution levels were high in spring, winter, fall, and the summer, but were lower in summer for all regions except for Ulsan. These differences are thought to be due to the dust in spring and the cleaning effect of precipitation in summer. The variation in concentrations during the day (diurnal variation) showed that $PM_{10}$ levels were very high during the rush hour and that this was most extreme in the cities (10.00 and 18.00-21.00). The total annual $PM_{10}$ emissions analysis suggested that there had been a general decrease, except for Jeju. On-road mobile (OM) sources, which contributed a large proportion of the particulates in most regions, decreased, but fugitive dust (FD) sources increased in the remaining regions, except for Daegu. The correlation analysis between $PM_{10}$ concentrations and emissions showed that FD could be used as a valid, positive predictor of $PM_{10}$ emissions in Seoul (74.5% (p<0.05)), Dajeon (47.2% (p<0.05)), and Busan (59.1% (p<0.01)). Furthermore, industrial combustion (IC) was also a significant predictor in Incheon (61.7% (p<0.01)), and on-road mobile (OC) sources were a valid predictor in Daegu (24.8% (p<0.05)).

• Tuberculosis and Respiratory Diseases
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• v.59 no.6
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• pp.690-695
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• 2005

Nitric acid is an oxidizing agent used in metal refining and cleaning, electroplating, and other industrial applications. Its accidental spillage generates oxides of nitrogen, including nitric oxide (NO) and nitrogen dioxide ($NO_2$), which cause chemical pneumonitis when inhaled. The clinical presentation of a nitric acid inhalation injury depends on the duration and intensity of exposure. In mild cases, there may be no symptoms during the first few hours after exposure, or the typical symptoms of pulmonary edema can appear within 3-24 hours. However, in cases of prolonged exposure, progressive pulmonary edema develops instantaneously and patients may not survive for more than 24 hours. We report a case of a 44-year-old male who was presented with acute respiratory distress syndrome after nitric acid inhalation. He complained of cough and dyspnea of a sudden onset after inhaling nitric acid fumes at his workplace over a four-hour period. He required endotracheal intubation and mechanical ventilation due to fulminant respiratory failure. He was managed successfully with mechanical ventilation using positive end expiratory pressure and systemic corticosteroids, and recovered fully without any deterioration in his pulmonary function.

• Journal of the Korean earth science society
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• v.36 no.1
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• pp.36-50
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• 2015

The purpose of this study is to assign emission source profiles of volatile organic compounds (VOCs) and particulate matters (PMs) for chemical speciation, and to correct the temporal allocation factor and the chemical speciation of source profiles according to the source classification code within the sparse matrix operator kernel emission system (SMOKE) in the Seoul metropolitan area. The chemical speciation from the source profiles of VOCs such as gasoline, diesel vapor, coating, dry cleaning and LPG include 12 and 34 species for the carbon bond IV (CBIV) chemical mechanism and the statewide air pollution research center 99 (SAPRC99) chemical mechanism, respectively. Also, the chemical speciation of PM2.5 such as soil, road dust, gasoline and diesel vehicles, industrial source, municipal incinerator, coal fired, power plant, biomass burning and marine was allocated to 5 species of fine PM, organic carbon, elementary carbon, $NO_3{^-}$, and $SO_4{^2-}$. In addition, temporal profiles for point and line sources were obtained by using the stack telemetry system (TMS) and hourly traffic flows in the Seoul metropolitan area for 2007. In particular, the temporal allocation factor for the ozone modeling at point sources was estimated based on $NO_X$ emission inventories of the stack TMS data.

• Applied Chemistry for Engineering
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• v.20 no.1
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• pp.9-14
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• 2009

A zwitterionic surfactant shows not only detergency but also softening effect since it shows characteristics of a nonionic or an anionic surfactant above an isoelectric point, while showing characteristics of a cationic surfactant below an isoelectric point. Therefore, a zwitterionic surfactant can serve as a dual function surfactant by a single molecule through the interconversion of cleaning and softening effects depending on pH of the aqueous solution. In this study, the dual function characteristics of an amine oxide zwitterionic surfactant were investigated by measuring the zeta potential and the isoelectric point using quartz crystal microbalance (QCM). In addition, the physical properties of an amine oxide surfactant such as critical micelle concentration, surface tension, interfacial tension, contact angle and viscosity were measured and phase behavior study was also performed. The isoelectric point of an amine oxide surfactant determined by zeta potential measurement was near 7.35 and that obtained by QCM experiment was about 7.4, where both results were found to be close to the value reported in the literature.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.731-736
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• 2019

In this article, Pt/TiO₂ was manufactured in the form of powder and honeycomb, and the influence of SO₂, which is a poisonous substance to catalyst, and regeneration method were investigated. The catalytic activity of Pt/TiO₂ before and after the exposure to SO₂ was also compared. The initial activity of Pt/TiO₂ was proportional to the injected H₂ concentration (1~5%). And the optimum temperature of the catalyst and conversion rate of H₂ were 183 ℃ and 95%, respectively. It was confirmed that when exposing 2,800 ppm of SO₂ to the powder and honeycomb Pt/TiO₂, the performance of catalyst was not measurable and also 0.69% sulfur (S) remained on the catalyst surface. As a result of the cleaning and heat treatment for the poisoning catalyst, the activity of the powder catalyst exhibited a conversion rate of H₂ greater than 96%. Whereas, the honeycomb catalyst showed a conversion rate of H₂ greater than 95% when it was regenerated through the heat treatment of H₂ or air atmosphere.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.730-738
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• 1992

Filtration characteristics according to membrane materials were studied In the ultrafiltration of anaerobic digestion broth as a post treatment method. A series of resistances for different membranes were quantitatively assessed on the basis of the resistance-in-series model. Flux behavior observed with the digestion broth was irrelevant to initial water permeabilities of each membrane. The fluoro polymer membrane showed the most significant improvement of flux with increase of cross-flow velocity, which suggests that the cake layer formed on this membrane is more weakly attached to the membrane surface than those on the other membranes. Flux reduction during longtime running was attrib-used to the polarization layer resistance ($R_p$) as well as the fouling layer resistance($R_f$). Continuous increase of $R_p$ may reflect the variation in the characteristics of cake layers, which could result from size, shape, and structure changes due to lysis and growth of biomass. Hydrophilic cellulosic membrane had a much lower fouling tendency than hydrophobic polysulfone membrane. The depressurization method induced a small increase in flux of $5-10L/m^2/h$. During washing and cleaning, filtrability of each membrane was rapidly recovered within 15 minutes until a stationary value was reached.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.4
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• pp.352-360
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• 2017

Objectives: This study aimed to determine the effects on musculoskeletal symptoms of both social demographic features and detailed characteristics of each task category of care workers who offer visiting home-help services. And to establish the measures that can reduce musculoskeletal symptoms among care workers. Methods: This study was conducted among 192 care workers from welfare centers C and K located in city P. After participants completed the task burden checklist regarding the scale of musculoskeletal symptoms and the details of their duties, the data collected were analyzed using the SPSS 21.0 program. Results: According to the degree of observable musculoskeletal symptoms in care workers, the highest figures were observed for back and shoulder pain. Based on the results of assessing the effect of detailed task category characteristics on musculoskeletal symptoms, "helping patients eat, helping patients move, helping patients bath, and changing body positions" were found to have an effect from the physical care category, "providing physical therapy assistance, treating bedsores" from the health care category, and "cleaning and doing laundry" from the facility management category. Conclusions: Due to the high proportion of patients requiring burdensome physical labor from care workers such as moving patients who have trouble doing so on their own, helping them change positions, and so on, it is highly likely that pain will occur in the low back, which carries most of the physical weight. So, education on human epidemiological positions that can reduce overload on areas prone to pain such as the low back and shoulders is essential. Proper equipment and personnel support must be provided for dangerous tasks. Further, multidimensional social support is required consistently.