• Environmental Engineering Research
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• v.20 no.2
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• pp.127-132
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• 2015

Perfluorooctane sulfonate (PFOS) and Perfluorooctanoic acid (PFOA) are persistent environmental pollutants, extremely stable, and possibly adversely affect human health. They are widely used in many industries and consumer goods, including sunscreen products. These substances are stable chemicals made of long carbon chains, having both lipid- and water-repellent qualities. The research objectives are (1) to find the most effective method for the preparation of semi-liquid samples by comparing solid phase extraction (SPE) and centrifugation after Pressurized liquid extraction (PLE), and (2) to determine the contamination levels of PFOS and PFOA in waterproof sunscreen samples. All sunscreen samples were analyzed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Sunscreen samples were purchased from domestic and international brands sold in Thailand. Special chemical properties were considered for the selection of samples, e.g., those found in waterproof, sweat resistant, water resistant, and non-stick products. Considering the factors of physical properties, e.g., operation time, chemical consumption, and recovery percentage for selecting methods to develop, the centrifugation method using 2 mL of extracted sample with the conditions of 12,000 rpm and $5^{\circ}C$ for 1 hour after PLE was chosen. The highest concentrations of PFOS and PFOA were detected at 0.0671 ng/g and 21.0644 ng/g, respectively. Even though present concentrations are found at ng/g levels, the daily use of sunscreen products is normally several grams. Therefore, a risk assessment of PFOS and PFOA contamination in sunscreen products is an important concern, and more attention needs to be paid to the long-term effects on human health.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.2
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• pp.308-318
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• 2009

The purpose of this study was to develop the functionally improved winter work clothing for the Korean railroad workers. Based on the questionnaires, the sample clothing for the Korean railroad workers was produced. The design, materials, and patterns were modified to increase mobility and comfort of workers. Water-repellent treatment was added to the material in order to decrease the dirt and stains while working. Also the reflective strips were added to chest and back of the upper garment in order to increase visibility and safety of the workers. In terms of the design and pattern underarm of the sleeve and side panel of the bodice were put in together and action pleats at the back were inserted in order to decrease the pullback of the armpit and scapular area and increase mobility of the arm movement. Also the patterns of the elbows areas were modified to increase mobility of joint. The prototype was evaluated an objective assessment and subjective assessment to compare to the existing working uniform. Assessment group was consisted of 5 subject groups and 11 expert groups and evaluated external appearance and adaptability to the movements. According to the results, the prototype was evaluated better than the existing working uniform in appearance and adaptability except height of collar. A field test was conducted to compare the prototype and the existing working uniform. The field tests were performed by 6 workers in the Korean railroad. According to the results, the prototype was improved in terms of adaptability and comfort.

• Science of Emotion and Sensibility
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• v.6 no.1
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• pp.27-32
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• 2003

The objectives of this study the effects of fabric noise from active wear on electrodiagnosis(EMG), to examine the effects on subjective sensation, and to relate the EMG results and the subjective sensation.. Five nylon water repellent taffeta fabrics were rubbed each other and the fabric noise were recorded. EMG was done from 10 female university students and electrodes were attached on each participant's upper arm and lower am. The subjective sensation was measured by FMME(Free Modulus Magnitude Estimation). The EMG values from upper arm showed higher voltage than those from lower arm, and the differences between values with fabric sound and without were larger at upper arm than those at lower am. EMG decreased when fabric sound was evaluated soft and pleasant, however It increased in proportion as fabric sound was evaluated loud and sharp. The predicted models for subjective sensation using physical sound properties and EMG results were well explained except roughness. Pleasantness was well predicted by EMG at upper am and EMG at lower arm, as the result, it was explained that the lower the EMG, the more pleasant the participant.

• Journal of the Korean Society of Clothing and Textiles
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• v.17 no.1
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• pp.151-161
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• 1993

The purpose of this study was to investigate the effect of hydrophilic finish for polyester (PET) fabric and hydrophobic finish for cotton fabric on the water transport and comfort properties. Polyester fabric was treated with 10% sodium hydroxide solution to impart hydrophilicity. Cotton fabric was sprayed with Scotch-gard$^{(R)}$ water and oil repellent finish to impart hydrophobicity. Porosity, air permeability, contact angle, wickability and water vapor transport rate (WVTR) were measured to determine the water transport properties of fabrics. To compare the comfort properties of treated and untreated fabrics, wear test was performed by putting fabric patches on the upper back: stratum corneum water content (SCWC), subjective wettedness and comfort rating were determined. The results were as follows: (1) The contact angle of water on treated polyester fabric was decreased and that of treated cotton fabric was increased. Also, the wickability of treated polyester fabric was increased and the wickability of cotton fabric was decreased. (2) Although each finish did not change porosity, the water vapor transport rate of treated polyester fabric was increased and that of treated cotton fabric was decreased slightly. (3) The results of stratum corneum water content measurements showed good agreement with the results of the contact angle and the wickability, i.e., the better the liquid water transport properties are, the less the stratum corneum water contents were resulted. (4) The realtionship of subjective wettedness or comfort and stratum corneum water content was independent. Therefore, it was concluded that human perception on the subjective wettedness or the comfort is affected by the skin contact of wet fabric rather than by the stratum corneum water content.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.320-320
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• 2011

We describe fabrication of superhydrophobic surface on non-woven fabric (NWF) having nano-hairy structures and a hydrophobic surface coating. Oxygen plasma was irradiated on NWF for nano-texuring and a precursor of HMDSO (Hexamethydisiloxane) was introduced as a surface chemical modification for obtaining superhydrophobicity using 13.56 MHz radio frequency-Plasma Enhanced Chemical Vapor Deposition (rf-PECVD). O2 plasma treatment time was varied from 1 min to 60 min at a bias voltage of 400V, which fabricated pillar-like structures with diameter of 30 nm and height of 150 nm on NWF. Subsequently, hydrophobic coating using hexamethyldisiloxane vapor was deposited with 10 nm thickness on NWF substrate at a bias voltage of 400 V. We evaluate superhydrophobicity of the modified NWF with sessile drop using goniometer and high speed camera, in which aspect ratio of nanohairy structures, contact angle and contact angle hysteresis of the surfaces were measured. With the increase of aspect ratio, the wetting angle increased from $103^{\circ}$ to $163^{\circ}$, and the contact angle hysteresis decreased dramatically below $5^{\circ}$. In addition, we had conducted experiment for nucleation and condensation of water via E-SEM. During increasing vapor pressure inside E-SEM from 3.7 Torr to over 6 Torr which is beyond saturation point at $2^{\circ}C$, we observed condensation of water droplet on the superhydropobic NWF. While the condensation of water on oxygen plasma treated NWF (superhydrophilic) occurred easily and rapidly, superhydrophobic NWF which was fabricated by oxygen and HMDSO was hardly wet even under supersaturation condition. From the result of wetting experiment and water condensation via E-SEM, it is confirmed that superhydrophobic NWF shows the grate water repellent abilities.

• Journal of the Mineralogical Society of Korea
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• v.18 no.2
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• pp.83-92
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• 2005

Dissolution rate of minerals may differ from climates configuration, but weathering rate of feldspars is generally proved to be relatively higher The result of geochemical reaction modeling indicates the acid water of pH 4.5 excluding any other variables, was 2.3 times higher than that in ordinary rain of pH 5.7. This result proved that pH is very important factor in preservation of granite cultural properties. To prevent the weathering of stone cultural properties, weathering characteristics of stones should be studied first and constitution of dry environments, using water repellent or oil coating, isolating water which cause chemical weathering reaction like hydration and oxidization should be considered. Considering the long-term reactions between granite and rain, selection of materials, which can bring neutralization and non-oxidization conditions, are very important in using cleaning agents and biological controls.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.11
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• pp.1611-1620
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• 2007

The precaution to spray with agricultural chemicals is very important, in particular personal protective equipment against pesticide in order to protect farmers# pesticide poisoning. The Ministry of Agriculture and Forestry has proclaimed the announcement of pesticide proof clothing(PPC) in 1983, and revised it in 1987. The announcement had many performance items to achieve the high-quality protective clothing for pesticide including weight, density, force strength, dimensional change(in washing and drying), fastness(dyeing, washing, sweating and rubbing) and water resistance of clothes. Announcement of the PPC has better durability and penetration resistance function than former days, but the plenty of farmers didn#t wear it because of the intolerable heat. To increase wearing rates, the pesticide proof clothing must be estimated the water-vapour resistance. From the results, the developed PPC with polyester treated water-repellent showed the more excellent comfort than an existing PPC with nylon coated polyurethane. But the developed PPC appeared to have the low water-vapour resistance. Therefore, it is suggested that the property of pesticide penetration must be evaluated through the field test in the future study.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.3
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• pp.410-419
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• 2009

The purpose of this study was to develop the functionally improved winter work clothing for the Korean railroad workers. Based on the questionnaires, sample clothing for the Korean railroad workers was produced. The design, materials, and patterns were modified to increase mobility and comfort for workers. Water-repellent treatment was added to the material in order to decrease the dirt and stains while working. Also, reflective strips were added to side seams and hems of the trousers in order to increase the visibility and safety of the workers. In terms of the design and pattern, a circumference of 4.5cm was added to the crotch area in order to minimize tightness on the hip and crotch areas, but no additional circumference was added to the hip area. And a 1cm width dart was inserted between the side seams and yoke in order to add activity. Also three 1.4cm width tucks were used at 2.5cm space on the knees to alleviate tightness at the knees. The prototype was evaluated objectively and subjectively to compare with the existing working uniform. The assessment group consisted of 5 subject groups and 11 expert groups to evaluate external appearance and adaptability of the movements. Subject and panels were asked to evaluate the prototype that followed an ergonomic design and pattern. According to the results, the prototype was evaluated better than the existing working uniform in appearance and adaptability. A field test was conducted to compare the prototype and the existing working uniform. The field tests were performed by 6 workers in the Korean railroad. According to the results, the prototype advanced in terms of adaptability and comfort.

• Applied Microscopy
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• v.42 no.2
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• pp.95-103
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• 2012

The cell surface sculpture of the plant epidermis has received great interest recently. It has also been an active area of research, as the biological microstructures of the surface, such as papillae and waxes, exhibit several unique properties, including self-cleaning character; namely the "Lotus effect" first described in the leaves of the lotus, Nelumbo nucifera. The Lotus effect is the phenomenon in which the super-hydrophobic and water-repellent nature of lotus leaves allow water drops to run off easily on the surface in a rolling and sliding motion thereby facilitating the removal of dirt particles. It is well-known that surface roughness on the micro- and nanoscale is a primary characteristic allowing for the Lotus effect. This effect is common among plants and is of great technological importance, since it can be applied industrially in numerous fields. In the present study, Nelumbo nucifera leaf and stem epidermal surfaces have been examined with a focus on the features of papillae and wax crystalloids. Both young and mature Nelumbo nucifera leaf epidermis demonstrated the Lotus effect on their entire epidermal surface. The central area of the upper epidermis, in particular, formed extremely papillose surfaces, with an additional wax layer, enabling greater water repellency. Despite the presence of wax crystalloids, epidermal surfaces of the lower leaf and stem lacking papillae, were much more easily wetted.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.228-236
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• 2015

In this research, the influence of painting materials and applying timing on carbonation and chloride resistances of high volume SCMs concrete was evaluated. As a durability improving method, comparative tests were conducted with painting materials of ERCO (emulsified refined cooking oil), RCO (refined cooking oil), WR (water repellent agent), and ERCO + WR and with painting timings of right after demolding, and 28 days after the wet curing. From the experiment results, in the case of carbonation and chloride resistance, the carbonation depth and chloride penetration depth were decreased when the painting materials were applied in 28 days of wet curing. Additionally, for painting materials, with the order of ERCO, RCO, ERCO+WR, and WR, the carbonation and chloride penentration was delayed. Hence it is considered that ERCO shows the most favorable performance of resistance against carbonation and chloride penetration.