• Journal of Korean Ophthalmic Optics Society
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• v.16 no.2
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• pp.135-145
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• 2011

Purpose: This study was conducted to investigate the actual condition of caring soft contact lens cases and the change in contamination level of lens cases by wearing and storage period of soft contact lens. Methods: The actual condition of caring soft lens cases was surveyed with sixty-three of contact lens wearers. Soft contact lenses were worn for 1, 3, 7 and 14 days, and the lenses were separately stored in 12 lens cases for 1, 3 and 7 days. The contamination level of lens cases was determined by counting the numbers of microorganisms, gram negative bacteria and fungi. Results: Only 14% of survey answerers cleaned their lens cases with a brush, rinsed and dried them upside down before next usage of lens case when those lenses were kept for a long time. Furthermore, 54% of total answerers just kept soft contact lens in the case without changing the multipurpose solution. Microorganisms, gram negative bacteria and fungi were detected in lens cases even when soft contact lens were kept for 1 day in the lens case after wearing for 1 day and cleaning it with multipurpose solution. The numbers of microorganisms, gram negative bacteria and fungi in lens cases increased with storage periods of soft contact lens, and also contamination level of lens cases was increased in accordance with wearing period of lens. In the lens cases without changing multipurpose solution, the numbers of microorganisms, gram negative bacteria and fungi increased with storage period of lens with statistical significance. Conclusions: This study showed that lens wearers' concerns on caring contact lens case were not satisfactory. As the result, the contamination of lens cases was related to increase of lens wearing and storage periods suggesting that the proper instruction and education for lens wearers are required.

• Archives of design research
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• v.18 no.2 s.60
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• pp.155-164
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• 2005

Home-service robots need to have sufficient spatial information about the surroundings for interacting with human intelligently and performing services efficiently. It is very important to investigate the efficient interaction style that supports map building task through human-robot collaboration. We first analyzed map building task with a cleaning robot and drew 4 design factors and tentative solutions, including map building procedure (task-preferred procedure/space- preferred procedure), LCD display installation (robot/robot+remote control), navigation method (push type/pull type), feedback modality(GUI/GUI+TTS). The design factors and tentative solutions were defined as independent variables and levels. This research investigated how those variables affect to the human task performance and behavior in map building tast. 8 kinds of experiment prototypes were built and usability test among 16 house wives was conducted for acquiring empirical data. As the experiment result, in terms of map building procedure, space-preferred procedure indicated better task performance than task-proffered procedure as we expected. For the LCD display installation factor, remote control with LCD display indicated higher task performance and subjective satisfaction. In robot navigation method, it was very difficult to find a significant difference between push type and pull type which contrary to our expectation. In fact, push type indicated higher subjective satisfaction. Also in feedback modality, we have acquired negative feedback an additional TTS operation guidance. It seems that robot's autonomy before achieving spatial information is rudiment condition which means users are just interacting with a mobile appliance. Thus they prefer remote-control-based interaction style in robot map building process as they used in traditional appliance control.

• Journal of dental hygiene science
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• v.16 no.3
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• pp.242-248
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• 2016

The purposes of this study were to investigate the factors affection the Oral Impacts on Daily Performances for Children (C-OIDP) in elementary and middle school students, and identify the association between oral health-related behaviors, oral health condition and C-OIDP. A cross-sectional study was conducted in three schools in Incheon, Asan, Korea. A total of 175 selected children were interviewed by a trained examiner using a questionnaire. Oral Health Related Quality of Life was assessed by the Korean version of C-OIDP. Socio-economic characteristics, oral health-related behaviors, oral health condition and C-OIDP were verified using the questionnaire. ANOVA analysis was performed to determine the oral health and C-OIDP, and multiple regression analysis was performed to determine the factors affecting the C-OIDP. The activities with the greatest effect were eating (28.0%), cleaning teeth (22.9%), and smiling (18.9%). In the logistic regression model, the high item score of C-OIDP was associated with experiencing dental caries and gum pain in the past month. The more the C-OIDP prevalence item, the more the fillng deciduous tooth surface (fs) (p=0.024), caries experienced deciduous tooth surface (dfs) (p=0.049), total caries tooth surface (ds+DS) (p=0.021), and total caries experienced tooth surface (dfs+DMFS) (p=0.047). It can be concluded that the factors affecting C-OIDP are fs, dfs, dfs+DMFS, and gingival pain. Based on these results, we can improve C-OIDP to advance preventive practice.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.4
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• pp.493-501
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• 2007

The membrane pilot plant has being operated in the Hyeondo pumping station to find the optimal operation technique of Gong-Ju membrane water treatment plant (WTP) which is constructing in $250m^3/d$ scale. The pilot plant was consisted of two trains which can treat $30,000m^3/d$ per train. First train was operated for one year under the condition of flux $1m^3/m^2{\cdot}d$ while the effects of flux variation and addition of powdered activated carbon(PAC) were evaluated in second train. The turbidity of membrane product water of first train which is operated on Flux $1m^3/m^2{\cdot}d$ was always below 0.05 NTU regardless of raw water turbidity. And also, the trance-membrane pressure(TMP) was maintained at $0.3{\sim}0.5kgf/cm^2$ for about 9 months and increased rapidly to $1.8kgf/cm^2$ which is maximum operating TMP. However, TMP was rapidly increased to $1.8kgf/cm^2$ within 2 months as flux was increased from 1 to $2m^3/m^2{\cdot}d$, especially, within 10 days under high turbidity(30~50NTU). This reault means that if Gongju membrane WTP is operated in flux $1m^3/m^2{\cdot}d$, chemical cleaning period can be maintained over 6 months. Only 10% of dissolved organic carbon (DOC) was removed in membrane process while the removal efficiencies of manganese and iron were 60% and 77% respectively. However, because only solid manganese and iron were removed in membrane process, an additional process for treating soluble manganese is required if souble manganese is high in raw water. 70% of 70ng/L 2-MIB which is causing taste & odor was removed in powdered activated carbon (PAC) tank with 50mg/L PAC which is design concentration of Gongju WTP. In addition, TMP was reduced with addition of 50mg/L PAC regardless of flux. Because TMP was not influenced even if 100mg/L PAC was added, the high taste and odor problem can be controled by additional injection of PAC.

• Journal of the Korean Society of Clothing and Textiles
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• v.36 no.4
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• pp.412-421
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• 2012

The yerba mate that grows in the subtropical forests of South America is an evergreen tree within the Aquifoliaceae family. The yerba mate (Ilex paraguariensis) tea is habitually used as a drink in Argentina, Paraguay, Uruguay, and Southern Brazil. A wild mate tree needs about 25 years to fully grow to 15 a height of meters; however, they only grow to a height of 3-5 meters when cultivated. The leaves are 7-11 cm long and 3-5cm wide with a serrated margin. Yerba mate tea-based beverages are made from the leaves and stems of the mate tree. It is known that they contain a rich content of antioxidants and polyphenol, vitamins, amino acids, minerals and colorants. Dyeing properties of a mate plant in the silk, wool, linen and cotton fabrics were investigated. Constituents of colorant of mate tea are chlorophyll and carotinoid; in addition, it has more minerals such as (Fe, Ca, Mn, Mg, Na, K, Zn, and Cu) than green tea. Mate tea colorants showed good affinity to silk and wool fabrics. It was found that the optimum condition for dyeing was 30 minutes for dyeing time, 7 for pH of dyebath, and at a dyeing temperature of $80^{\circ}C$. The maximum absorbance wavelength (${\lambda}_{max}$) of silk and wool fabrics dyed with mate tea were at 420-440nm; however, that of linen and cotton fabrics were at 400nm. K/S values of fabrics dyed under optimum conditions were 1.979 for silk fabrics, 1.541 for wool fabrics, 0.551 for linens and 0.465 for cotton fabrics. Munsell hue values of dyed fabrics measured 3.1Y-6.4GY for silk, 1.4Y-8.3Y for wool, 5.5Y-3.7GY for linen, and 5.3Y-1.3GY for cotton. All dyed fabrics showed hues in-between greenish yellow and greenyellow. Colorfastness to rubbing, perspiration and dry-cleaning of dyed fabrics with mate tea were very good; however, the grades of colorfastness to washing of dyed linen and cotton fabrics were poor, and colorfastness to light were poor.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.1
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• pp.67-73
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• 2013

Purpose: Recently, bacterial contamination of equipment and accessories required for vision correction has become a main causal factor in ophthalmic diseases. Thus, We investigated on both the actual condition of bacterial contamination from glasses of vision correction. Methods: Investigation of microorganisms was carried out with a group of 145 glasses wearers, composed of 36 elementary school students, 37 middle school students, 38 high school students, 10 college students, and 32 aged men. Results: Seventeen species of bacteria are detected from glasses of vision correction: B. cereus, B. licheniformis, Bacillus sp., CNS, Enterococcus sp., Escherichia coli, Proteus sp., Pseudomonas sp., Serretia sp., Streptococcus sp., Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus hemolyticus,, Acinetobacter sp., Enterobacter cloacae, GNR, and Pseudomonas aeruginosa. Among 17 species of bacteria, there are some potential causative agents for keratitis, corneal ulcer, Acute dacryocystitis, Orbital cellulitis, Periphlebitis retinae, Marginal blepharitis, and Acute conjunctivitis. Enterobacter cloacae, Pseudomonas aeruginosa and Staphylococcus epidermidis cause keratitis. Pseudomonas sp., and Staphylococcus aureus cause corneal ulcer. Staphylococcus aureus causes acute dacryocystitis, orbital cellulitis, periphlebitis retinae, marginal belpharitis. Streptococcus hemolyticus causes acute conjunctivitis. Conclusions: In summation, it is verified that hazardous, opportunistic and infectious microorganisms exist in glasses for vision correction. Ophthalmic diseases are predicted. Therefore, supplementary research on the development of a cleaning solution to cleanse the infection and of an effective method to remove microorganisms is required.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.11
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• pp.15-19
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• 2007

This paper reports the effects of Ar ion beam surface treatment on a $SiO_2$ dielectric layer in organic thin film transistors. We compared the electrical properties of pentacene-based OTFTs, treated by $O_2$ plasma or Ar ion beam treatments and characterized the states of the surface of the dielectric by using atomic force microscopy and X-ray photoelectron spectroscopy. For the sample which received $O_2$ plasma treatment, the mobility increased significantly but the on/off current ratio was found very low. The Ar ion beam-treated sample showed a very high on/off current ratio as well as a moderately improved mobility. XPS data taken from the dielectric surfaces after each of treatments exhibit that the ratio of between Si-O bonds and O-Si-O bonds was much higher in the $O_2$ plasma treated surface than in the Ar ion beam treated surface. We believe that our surface treatment using an inert gas, Ar, carried out an effective surface cleaning while keeping surface damage very low, and also the improved device performances was achieved as a consequence of improved surface condition.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.3
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• pp.155-163
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• 2017

Membrane filtration has become more popular in drinking water treatment recently, since the filtration can control not only particulate matters but also pathogenic microorganisms such as giardia and cryptosporidium very effectively. Pilot-scale ($120m^3/d$ of treatment capacity) and test-bed ($25,000m^3/d$ of treatment capacity) microfiltration experiments were conducted to find optimum operating mode and the critical flux. Optimum operating mode of pilot-test was assessed as inflow 1.0 min, filtration 36.5 min, air backwash 0.9 min, backwash 1.0 min and outflow 1.0 min with 50 LMH ($L/min{\cdot}m3^$) of critical flux. Critical Flux was calculated to be $50L/m^2-h$ (within TMP 0.5 bar) based on the increase formula of the transmembrane pressure difference according to the change of time at Flux 20, 40, 56 and 62 LMH in pilot operation. Chemical cleaning was first acid washed twice, and alkali washing was performed secondarily, and a recovery rate of 95% was obtained in the test-bed plant. The results of operating under these appropriate conditions are as follows. Turbidity of treated water were 0.028, 0.024, 0.026 and 0.028 NTU in spring, summer, autumn and winter time, respectively. Microfiltration has superior treatment capability and performance characteristics in removing suspended solids and colloidal materials, which are the main cause of turbidity and important carrier of metal elements, and it has shown great potential in being an economically substitute to traditional processes (sand filtration).

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.154-159
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• 1999

EDTA (ethylenediaminetetraacetic acid), a chelating agent is most widely used in industrial applications, especially for cleaning of metals in water, frequently prohibits metal removal from water in conventional water treatment technologies. It could be easier to remove aqueous metal ions by the breakdown of DETA complexed bonds first. This study investigated the availability of $TiO_2$ photo-catalysis for the aqueous phase oxidation of Cu(II)-EDTA, under an aerobic condition at $20^{\circ}C$ with $TiO_2$ (Degussa P-25) and 1.79mM of Cu(II)-EDTA. When $TiO_2$ loading was 2.0 g/L, the photo-catalytic oxidation of Cu(II)-EDTA was maximal. The tendency of EDTA adsorption onto the catalyst surface was affected by $TiO_2$ surface charge, and the oxidation rate of Cu(II)-EDTA by photo-catalysis was shown to be dependent upon the tendency of EDTA adsorption before photo-irradiation.

• Membrane Journal
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• v.21 no.2
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• pp.127-140
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• 2011

The effects of $TiO_2$ photocatalyst coating bead concentration, water-back-flushing period (FT), and back-flushing time (BT) were investigated in hybrid process of ceramic ultrafiltration and photocatalyst for advanced drinking water treatment in this study. Photocatalyst coating bead concentration was changed in the range of 10~40 g/L, FT in 2~10 min and BT in 6~30 sec. Then, we observed the effects on resistance of membrane fouling $(R_f)$, permeate flux (J) and total permeate volume $(V_{\Upsilon})$ during total filtration time of 180 min. As decreasing photocatalyst coating bead concentration, $R_f$ increased and J decreased. $V_{\Upsilon}$ was the highest value of 8.85 L at 40 g/L of photocatalyst coating bead concentration. At FT change experiment, $R_f$ decreased and J increased as decreasing FT. Then $R_f$ decreased and J increased according to increasing BT at BT change experiment. Because at NBF (no back-flushing) dramatic membrane fouling reduced membrane pore size, turbid and dissolved organic matters ($UV_{254}$ absorbance) could be removed efficiently. Therefore, treatment efficiencies of turbidity and dissolved organic matters were the highest at NBF. Then by cleaning effect of photocatalyst coating bead, the treatment efficiencies of turbidity and dissolved organic matters increased as decreasing FT and increasing BT.