• Clean Technology
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• v.19 no.2
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• pp.184-188
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• 2013

To increase flash point which is related to flammability, seven unprecedented new cleaning agents containing fluoride atoms have been invented. These newly synthesized cleaning agents's physical properties which were conducted by Korea Institute of Petroleum Management by using a standard method showed excellent values. Particularly, flash point of newly synthetic cleaning agents is more higher than that of fluoride free compound. A specimen for cleaning ability was prepared by cutting in $60mm{\times}40mm$ size of stainless steel plate. The surface of the above specimens was applied with four kinds of contaminants, such as paraffin based drawing oil, flux abietic acid, water-insoluble cutting oil, and lubricating oil. Contaminated specimens were immersed in new compounds (1-7) for 1 to 5 minutes to dissolve oil in the cleaning agent. Although the data indicate that all compounds (1-7) exhibit lower cleaning ability toward cutting oil, it is observed that in the case of the present study more than 80% of pollutants on the surface were almost removed within 5 minutes.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.4
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• pp.25-32
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• 2010

The beeswax-treated volumes of the Annals of Joseon Dynasty, designated as a UNESCO's Memories of the World, have been more seriously damaged than the untreated ones. As a continuous effort to develop the optimal conservation techniques for the damaged beeswax-treated volumes of the Annals, this study examines the effectiveness of wet cleaning on the conservation of the beeswax-treated paper. To do this, wet cleaning is performed on the duplicated beeswax-treated paper and the Hanji that are aged at $105^{\circ}C$ for 30 days using distilled water of $24^{\circ}C$ and $50^{\circ}C$. As results, it is observed that pH of the both the beeswax-treated paper and the Hanji increase, indicating the removal of the acid of the aged paper samples through wet cleaning. After the wet cleaning, however, the physical properties and viscosity of the Hanji decrease, while those of the beeswax-treated paper increase. It is also found that wet cleaning contributes to enhancement of most optical properties of the Hanji, but not for those of the beeswax-treated paper except for the $b^*$ value. Analyses of UV absorbance of cleaning water demonstrate that both the beeswax-treated paper and the Hanji have typical spectra of chromophore compounds of cellulose.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.399-405
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• 2011

In a desalination technology using RO membranes, chemical cleaning makes damage for membrane surface and membrane life be shortened. In this research cleaning technology using direct osmosis (DO) was introduced to apply it under the condition of high pH and high concentration of feed. When the high concentration of feed is injected to the concentrate side after release of operating pressure, then backward flow occurred from treated water toward concentrated for osmotic pressure. This flow reduces fouling on the membrane surface. Namely, flux of DO was monitored under pH 3, 5, 10 and 12 conditions at feed concentrations of NaCl 40,000 mg/L, 120,000 mg/L and 160,000 mg/L. As a result, DO flux in pH 12 increased about 21% than pH 3. DO cleaning was performed under the concentrate NaCl 160,000 mg/L of pH 12 during 20 minutes. Three kinds of synthetic feed water were used as concentrates. They consisted of organic, inorganic and seawater; chemicals of SiO2 (200 mg/L), humic acid (50 mg/L) sodium alginate (50 mg/L) and seawater. As a result, fluxes were recovered to 17% in organic fouling, 15% in inorganic fouling and 14% of seawater fouling after cleaning using DO under the condition of concentrate NaCl 160,000 mg/L of pH 12.

• Journal of the Korean Applied Science and Technology
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• v.20 no.4
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• pp.283-288
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• 2003

Alkaline powder cleaning agents (APCAs) were prepared by blending of $Na_2CO_3$ tetrasodium pyrophosphate (TSPP). sodium orthosilicate (Na-OSi), Na-dioctyl sulfosuccinate (303C), Demol C, and MJU-100A (100A). The physical properties of APCAs tested with steel specimen showed the following results. The cleaning powers of APCA-6 ($Na_2CO_3$ 250g/TSPP 70g/Na-OSi 40g/303C 60g/Demol C 50g/100A 30g mixture) for press-rust preventing oil was 97% and 98% degreasing at 2wt%, $70^{\circ}C$ and $90^{\circ}C$, respectively; for Quenching oil, the cleaning power of APCA-6 was 95% degreasing at 2wt% and $70^{\circ}C$. From the results, it was ascertained that APCA-6 exhibited a good cleaning power. Also low foaming power tests proved that the APCA-6 maintained good defoaming effect.

• Journal of Environmental Health Sciences
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• v.32 no.5 s.92
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• pp.478-484
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• 2006

There was no significant difference in the CADR (Clean Air Delivery Rate) between physical aerosols, NaCl and smoke, and biological aerosols, airborne MS2 virus and P. fluorescens, which implicate that the hybrid-type of air purifier, applying the unipolar ion emission and the radiant catalytic ionization, imposed identical reduction effect on both physical aerosol and bioaerosol. Ventilation decreases the efficiency of air cleaning by unipolar ionization because high ventilation diminishes the particle concentration reduction effect. The particle removal efficiency decreases with increase in the chamber volume because of the augmented ion diffusion and higher ion wall loss rate. Particle size affects the efficiency of air ionization. The efficiency is high for particles with very small diameter because reduction of charge increases with particle size. If there is no increasing supply of ions, the efficiency of air cleaning by unipolar ionization increases with respect to initial concentration of particles because of the large space charge effect at high particle concentration and amplified electric field.

• Clean Technology
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• v.14 no.3
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• pp.184-192
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• 2008

Fluoride-type cleaning agents such as 2,2,2-trifluoroethanol (TFEA) and hydrofluoroethers (HFEs) do not destroy ozone in the stratosphere and have low global warming potential compared to hydrofluorocarbons(HFCs) and hydrochlorofluorocarbons (HCFCs). Especially, HFEs which have no flash point are paid attention as next generation type of cleaning agents for chlorofluorocarbons (CFCs) since they are safe in handling and have excellent penetration ability compared to hydrocarbon cleaning agents with low flash point. Here, the physical properties and cleaning abilities of fluoride-type cleaning agents such as TFEA, HFE-7100, HFE-7200, HFE-476mec, HFE-449mec-f, AE-3000 and AE-3100E and silicide-type cleaning agents such as trifluoroetoxytrimethylsilane (TFES) and hexamethyldisilazane (HMDS) were measured and compared with those of ozone destruction substances such as CFC-113 and 1,1,1-trichloroethane. They were also compared with toxic methylene chloride (MC) and isopropyl alcohol (IPA) which are now being used as an alternative cleaning agents. As a result, TFEA and HFEs had lower cleaning ability for removal of various soils compared to chloride-type cleaning agents, but they showed excellent cleaning ability fur fluoride-type soils. TFES and HMDS also showed excellent cleaning ability for silicide-type soils.

• Clean Technology
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• v.13 no.2
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• pp.143-150
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• 2007

The objective of this study is to develop hydrocarbon-based cleaning agents by blending paraffins, glycol ethers and siloxanes in oder to effectively clean contaminants such as flux, solder and grease. And the effect of cleaning ability by wetting index, aniline points and solubility parameter of the formulated hydrocarbon-based cleaning agents were studied in this work. The formulated hydrocarbon-based cleaning agents were prepared on the base of physical properties of their individual components. Wetting indexes and aniline points of their were measured through experiments and solubility parameters of their were calculated based on the Hansen's equation. In this study, evaluation of cleaning ability by cleaning agents were carried out using contaminants such as flux, solder, and grease. The experimental results showed that the cleaning ability of the formulated cleaning agents was excellent in cleaning contaminants such as flux, solder and grease and that the influencing parameters on their cleaning efficiency were found to be different according to contaminant types. MC($20.3MPa^{1/2}$), DF-1 ($24.2MPa^{1/2}$) and DF-2($21.5MPa^{1/2}$) with similar solubility parameter as flux ($21.3MPa^{1/2}$) showed 100% cleaning efficiency within 3 minutes in flux cleaning. And CFC-113, MC and 1,1,1-TCE with low aniline point less than $-20^{\circ}C$ showed excellent cleaning efficiency in solder cleaning. DG-1($16.2\;MPa^{1/2}$) and DG-2($15.5\;MPa^{1/2}$) with similar solubility parameter as grease($15.0{\sim}17.0\;MPa^{1/2}$) showed relatively low cleaning efficiency of grease, but CFC-113 and MC with high wetting index and low aniline point showed good cleaning efficiency in grease cleaning. As a result of this study, the hydrocarbon-based cleaning agents alternative to regulated cleaning agents such as CFC-113, 1,1,1-TCE and MC were able to be developed through properly blending paraffins, glycol ethers and siloxanes for cleaning flux, solder and grease. And it can be shown that various influencing parameters of cleaning efficiency such as wetting index, aniline point, solubility parameter and etc. of the non-aqueous cleaning agent should be reviewed for prediction of their cleaning ability and can be applied to formulation of cleaning agents.

• Journal of Industrial Technology
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• v.37 no.1
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• pp.12-15
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• 2017

It is important in dentistry that the provisional cement should be cleaned thoroughly from the crown before definitive cementation. The provisional cement has been removed by physical means such as curette, scaler, pumice, or sand-blasting with alumina particles, which is time-consuming, irritating, tedious, even causing crack. To avoid such troubles occurring through such physical cleaning means, the chemical solutions for dissolving the provisional cement remaining in dental crown were prepared, and solubilizing power of the solutions was measured and compared. The solution composed of MEA, NaOH, chloride chemicals ($CHCl_3$, $CCl_4$, $CH_2Cl_2$), surfactants (Igepal, Tween20), chelating agent (EDTA), and Ethyl cellosolve was most effective for dissolving the provisional cement.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.576-582
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• 2015

The efficiencies of thermal power system using fossil fuel depend on heat exchangers which extract energy from the exhaust gas before it is expelled to the atmosphere. To increase heat transfer efficiency it is very important to maintain the surface of heat exchanger as clean condition. The accepted skill of cleaning of fouled surface of heat exchanger is soot blowing. A high pressure jet of air is forced through the flat surface of plate to remove the deposit of fouling. There is, however, little knowledge of the fundamental principles of how the jet behave on the surface and how the jet actually removes the deposit. Therefore, the study focuses on the measuring of cleaning area and cleaning dwell time after accumulating the simulated deposit on the flat surface. The deposit test rig was built for the study and simulated deposit material is used after measuring the physical property of the each material by shearing stress test. Much data was obtained for the analysis by the parameters change such as the different jet speed, different inner pressure and variable distance of the jet from the test rig surface. The experimental data was compared with the theoretical equation and most of the data matches well except some extreme cases.

• Korean Journal of Occupational Health Nursing
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• v.24 no.3
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• pp.183-193
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• 2015

Purpose: The purpose of this study was to describe cleaning workers' working experiences in Korea. Methods: The data were collected in two focus-group interviews with 9 cleaning workers. The phenomenological analytic method suggested by Colaizzi was used to analyze the data. Results: Five theme clusters and thirteen themes emerged from the analysis. The first theme clusters, 'Dead-end choice' included Limits of elderly women workers, Financial difficulties, Lowered self-esteem. The second theme clusters, 'Facing with discriminatory working environments' included Fear and unfair working conditions. The third theme clusters, 'Potential health problems' included Physical overload, Repeated exposure to hazardous substances and Emotional labor. The fourth theme clusters, 'Excluded from protection of the law' included Gloomy reality and Sexual harassment. The fifth theme clusters, 'Desire to get out of social isolation' included Efforts to maintain the status, Desire to live confidently and Desire to change social recognition. Conclusion: The findings of the study provide understanding on cleaning workers' working experiences to explain by their vision and language and should ensure proper working conditions and environment to live a better life.