• Korean Journal of Materials Research
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• v.28 no.11
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• pp.620-626
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• 2018

Highly self-cleaning thin films of $TiO_2-SiO_2$ co-doped with Ag and F are prepared by the sol-gel method. The asprepared thin films consist of bottom $SiO_2$ and top $TiO_2$ layers which are modified by doping with F, Ag and F-Ag elements. XRD analysis confirms that the prepared thin film is a crystalline anatase phase. UV-vis spectra show that the light absorption of $Ag-F-TiO_2/SiO_2$ thin films is tuned in the visible region. The self-cleaning properties of the prepared films are evaluated by a water contact angle measurement under UV light irradiation. The photocatalytic performances of the thin films are studied using methylene blue dye under both UV and visible light irradiation. The $Ag-F-TiO_2/SiO_2$ thin films exhibit higher photocatalytic activity under both UV and visible light compared with other samples of pure $TiO_2$, Ag-doped $TiO_2$, and F-doped $TiO_2$ films.

• Journal of the Korean Solar Energy Society
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• v.35 no.1
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• pp.21-28
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• 2015

A small washer powered directly and solely by thermal radiation was constructed and tested to explore the feasibility of using solar energy or other types of thermal radiation for washing and cleaning. In principle, TA (ThermoAcoustic) washers have the benefits of simpler design and operation and fewer energy conversion processes, thus should be more energy efficient and cost less than electric washing/cleaning systems. The prototype TA converter we constructed could sustain itself with consistent fluid oscillations for more than 20 minutes when powered by either concentrated solar radiation or an IR (infrared) heater. The frequencies of water oscillations in the wash chamber ranged from 2.6 to 3.6 Hz. The overall conversion efficiency was lower than the typical efficiencies of TA engines. Change in water temperature had little effect on the oscillatory flow in the TA washer due to its low efficiency. On the other hand higher water temperatures enhanced grease removal considerably in our tests. Methods for measuring the overall conversion efficiency, frictional loss, and grease removal of the TA washing system we designed were developed and discussed.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.4
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• pp.138-146
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• 2007

There are still lots of areas where are covered with combined sewer pipes in Seoul. All buildings within those areas are equipping septic tanks which take part in separating solids from flushing water of chamber pots. Septic tanks legally demand emptying and cleaning the those inner bodies, resulting the generation of sludge which should be purified using the specified treatment plants, as one of environmental infrastructures. Scale of treatment plants for septic tank sludge are affected by sludge volume generated from cleaning, which give emphasis to adequate estimation of sludge volume in the future. This study aimed to define prediction tools for sludge volume. Among various parameters, floor area of building is most reasonable one to estimate the quantity of cleaning sludge, showing increasing gradually up to 13,149kL a day in 2020. Using same parameter also are able to assess the amount of BOD in the cleaning sludge.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.64-72
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• 2004

The dryer (ten per unit) are operating to remove tritium in PHWR(Pressurized Heavy Water Reactor). There are coming out heavy water adsorbent from operating the dryer (95 drums for ten year per unit) The amount of radioactivity of heavy water adsorbent almost exceed ninety times more than disposal limit-in-itself showed by The Ministry of Science and Technology. It has to be disposed whole radioactive waste products, however there are problems of increase at the expense of their permanent disposal. In this research, We have studied how to remove kinds of nuclear materials and amount of tritium with in heavy water adsorbent. As the result we could develop disposal equipment and apply it. D20 adsorbent have to contain below Gamma nuclide O.3Bq/g and tritium 100Bq/g "The Regulation for disposal of the radioactivity wastes" showed by The Ministry of Science and Technology. There fore. So as to remove amount of tritium and kinds of nuclear materials (DTO) we needed a equipment. Also we have studied how to remove effectively radioactivity with in Adsorbent. As cleaning heavy water adsorbent and drying on each condition (temperature for drying and hours for cleaning). Because there is something to return heavy water adsorbent by removing impurities within adsorbent when it is dried o high temperature. After operating, we have been applying this research to the way to dispose heavy water adsorbent. Through this we could reduce solid waste products and the expense of permanent disposal of radioactive waste products and also we could contribute nuclear power plant run safely. According to the result we could keep the best condition of radiation safety super vision and we could help people believe in safety with Radioactivity wastes control for harmony with Environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.275-279
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• 1977

During the experimental rearing period of common carp in a small simple recirculating aquarium combined with frequent exchanges of water and cleanings, some observations were made on the conditions of fish growing which was directly and instantly affected by the cleaning frequency of strainer, changing rate of water, division and frequency of feed supply, prohibition of excess feeding and the amount of dissolved oxygen. The fish don't seem to be stressed by the manipulation for the change of rearing water, cleaning of detritus in the strainer and filter. It appeared that the most hazzardous matters to fish growth were : 1) supplying feed when fish do not show active response to feed supplied, and 2) giving ample amount of feed at one time. When especially the amount of the feed is within the range fish instantly can swallow, the water clarity is maintained even after feeding operation, but if any excess amount is given the fish intake into mouth much more feed than able to instantly swallow and try to swallow it resulting in much dissolving and suspension of feed materials in water, making the water quite cloudy. Consequently all the water as well as filter bed becomes significantly polluted.

• Membrane and Water Treatment
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• v.11 no.2
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• pp.97-109
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• 2020

Membrane fouling is the main drawback of membrane technology. Frequent membrane cleaning and membrane replacement are, therefore, required to reduce membrane fouling that causes permeate flux reduction, lower rejection, or higher operating pressure. Studies have proved that the alteration of membrane properties is the key controlling factor in lessening membrane fouling. Among stimuli-responsive membranes, thermo-responsive membrane is the most popular, with a drastic phase transition and swelling-shrinking behavior caused by the temperature change. In this study, the thermo-responsive ability of two commercial membranes, PolyCera® Titan membrane and PolyCera® Hydro membrane, at different temperatures was studied on the antifouling function of the membrane in palm oil mill effluent (POME) treatment. The evaluation of the membrane's thermo-responsive ability was done through three cycles of adsorption (fouling) and desorption (defouling) processes in a membrane filtration process. The experimental result depicted that PolyCera® Hydro membrane had a higher membrane permeability of 67.869 L/㎡.h.bar than PolyCera® Titan membrane at 46.011 L/㎡.h.bar. However, the high membrane permeability of PolyCera® Hydro membrane was compensated with low removal efficiency. PolyCera® Titan membrane with a smaller mean pore size had better rejection performance than PolyCera® Hydro membrane for all tested parameters. On the other hand, PolyCera® Titan membrane had a better hydrodynamic cleaning efficiency than PolyCera® Hydro membrane regardless of the hydrodynamic cleaning temperature. The best hydrodynamic cleaning performed by PolyCera® Titan membrane was at 35℃ with the flux recovery ratio (FRR) of 99.17 ± 1.43%. The excellent thermo-responsive properties of the PolyCera® Titan membrane could eventually reduce the frequency of membrane replacement and lessen the use of chemicals for membrane cleaning. This outstanding exploration helps to provide a solution to the chemical industry and membrane technology bottleneck, which is the membrane fouling, thus reducing the operating cost incurred by the membrane fouling.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.7
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• pp.1030-1039
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• 1999

The effect of surfactant mixture 9on detergency and soil redeposition in a dry-cleaning system was investigated employing Aerosol OT as an anionic surfactant and Span 80 as a nonionic surfactant. The effect of charge system on soil deposition was also investigated in order to determine the optimum condition at which soil redeposition is minimum,. Soil deposition instead of soil redeposition on cotton, polyester and wool fabrics was measured employing petroleum solvent and perchloroethylene as organic solvents. The results were as follows. 1. Surface tension or interfacial tension was not changed by the addition of any surfactant or surfactant mixtures. In petroleum solvent however interfacial tension between solrent and water decreased when surfactants were added and increased when surfactants were mixed,. 2. The maximum amount of water solubilization increased as the mole fraction of Aerosol OT increased and more water was solubilized in petroleum solvent than in perchloroethylene. 3. The detergency of cotton was greater and the soil deposition rate was lower in Span 80 solution than in Aerosol OT solution. The soil deposition on cotton fabric decreased when water was solubilized in Aersol OT solution 4. The detergency and soil deposition rate of polyester fabric did not change by the surfactant type of the addition of surfactant mixture and soil deposition rate increased bywater solubilization. 5. Soil deposition on wool fabric was very high when Arosol OT was employed in perchloroethylene and the soil deposition did not change greatly by water solubilization.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.8
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• pp.1313-1323
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• 2004

In accordance with adoption of new convention for the control of ship's ballast water at the diplomatic conference held in London Feb, 2004, every country has to regulate the ballast water and deposit matters. When this Resolution comes into effect in 2009, all vessels engaged in international voyage must have ballast water control program, ballast water records, equipments which are suitable to the standard of exchange and performance for the ballast water. This study estimates objectively their performances, merits and demerits of the ballast water treatment technique and exchanging techniques for safe operation of ships. It is desirable to design an equipment to control the ballast water using the brush-type vacuum suction nonstop reverse cleaning system to overcome the clogging phenomenon and the direct disc filtering to maximize filtering area for the optimum process considering biological availabilities. It will be expected to protect against marine pollution and to maintain clean sea if it is secured to develop new ballast water treatment techniques. And it will also be expected to cope with the Resolution and each regulation of the developed countries from the ballast water.

• Journal of Environmental Health Sciences
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• v.23 no.2
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• pp.28-34
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• 1997

This study was carried out to investigate the effects of prechlorination and algae growth on THMs generation. The sample water obtained from Paldang Dam which is a main source of raw water for the Seoul metropolitan area. THMs concentration in the sample water was investigated in water treatment process prechlorifiation, chemical coagulation, and sand filtration. And also, THMs concentration were analyzed in the water which cultured algae in laboratory. The results were as follows 1. The THMs concentration produced by prechlorination unit process were increased in control (not purified) but decreased in process of purification. 2. The THMs concertration can reduce by increasing the number of cleaning filters. 3. The main precursor in raw water for the THMs generation was supplied by algae growth. So as to reduce the THMs concentration in water supplying system, it is the best method to manage algae growth in water body of Paldang reservoir.

• Journal of Environmental Health Sciences
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• v.4 no.1
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• pp.26-33
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• 1977

A bacteriological research of the school desks, bags and indoor-shoes was made from Oct. 2, 197 through May 28, 1976. The research included one girl's middle school, two boy's middle schools, two boy's high schools and 15 girl's high schools, alltogether 244 students from 28 schools, The research was analyzed and the results are as follows: 1) The research showed that 95% of the indoor-shoes materials were of cloth. Only 13% of the students carried the indoor-shoes in shoes sacks and 84.8% of them kept the shoes in schoolbags with books and lunchbox. 2) Only 5% of them cleaned their shoes every week and 79% cleaned every six. 3) 49.3% of the students kept the indoor-shoes in the school bag with other contents at home. 4) 88% of the bag was made of vinyl and 24.8% of the students carried their lunch in their bag without lunch box. 5) The research showed that 79.1% of the students never cleaned their bags. 6) In using the desk drawer, 58.2% of the students put their out-door shoes into the drawer, 18.9% of them kept their lunch in it, 11.9% used it keeping books alone and 11% keeping school bags with books. 7) 30.4% of the students had an experience of having cleaned their desks and 69.6% were unconcerned wirh desk-cleaning. 8) 34.4% of the indoor-shoes using school showed fecal coliform positive, 40.2% showed non-fecal coliform positive and 25.4% showed no reaction to IMViC. 9) The 34.4% of the fecal coliform positive showing schools, equivalant to 77 students, was composed of zero percents of girl's middle school, 18.2% of girl's high school, 36.4% of boy's middle school and 45.4% of boy's high school. 10) Among the 77 students, whose shoes showed fecal coliform positive, only 6.5% of them cleaned their shoes once in a week or a month and 62.3% of them cleaned them once in a six month. 11) The fccal coliform positive rate was higher in the cloth shoes materials than the vinyl materials. 12) The concrete-bottomed building higher positive rate (40.2%) than the wood-bottomed building (7.5%). 13) Even among the student's who frequently cleaned their desk drawer, 2.3% were in the positive, and among those who were unconcerned with drawer cleaning, 48.9% were involved in the positive. 14) In the fecal coliform positive rate of bags, 38.5% of the positive rate belonged to using indoor shoes while cleaning their class bottom with water, 53.8% belonged to using outdoor shoes while cleaning their class bottom with water, 7.7% belonged to using outdoor shoes while cleaning their class with oil.