• Elastomers and Composites
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• v.38 no.3
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• pp.243-250
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• 2003

Polyurethane waterproof (PW) coatings are increasingly demanded in Korea for repairing cracks on old building roofs and construction of many sporting facilities. Calcium carbonate, a common filler, is incorporated in PW compositions. In this study, PW coatings were prepared by substituting a part of calcium carbonate with fly ash. The maximum amounts of calcium carbonate which can be substituted by fly ash obtained in the cyclone and bag filter dust collectors were 20 and 10%, respectively. It was found that the curing rate of PWs ran be controlled by varying the amount of Pb-octoate catalyst. The elongations at break as well as tensile strength and tear strength of PW coatings containing fly ash could also be adjusted such that their values were comparable to those of a standard PW coating by varying relative amounts of some components. However, the amount of cadmium, mercury, and lead leached from PW coatings containing fly ash obtained from the bag filter collector exceeded the respective allowed upper limits, mainly due to the initial high contents of them in the fly ash. On the other hand, PW coatings containing fly ash obtained from the cyclone collector exhibited better mechanical properties and did not release any significant amounts of the heavy metals. Thus, it was concluded that PW coatings containing fly ash can be utilized for practical applications as long as an appropriate fly ash is used.

• Journal of Conservation Science
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• v.37 no.3
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• pp.302-311
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• 2021

This study uses traditional lacquer techniques to coat the metal surface and evaluates its physical properties to check the applicability of the lacquer coating. For this purpose, a total of six specimens were produced by setting the variation conditions for the number of times (1, 2, 3) and the heating temperature (120℃, 150℃) using SS275 metal(60*60 mm) and 'Wonju lacquer'. For analysis, chromaticity measurements, contact angle/surface energy measurements, Chemical Resistance, and cross-cut tests were used. The analysis showed that the corrosivity was improved and the adhesion of lacquer to the metal surface was excellent. There was no significant change in contact angle/surface energy. Also, there was no significant difference in color. Through this study, it was confirmed that lacquer on metal surfaces improves waterproofing and has a anticorrosion effect. We could also check the proper number of lacquer and heating temperature. Additional physical characteristics such as hardness and wear rate should be studied. It is also necessary to study how lacquer can be painted with a certain thickness.

• Textile Coloration and Finishing
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• v.22 no.3
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• pp.239-245
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• 2010

Breathable waterproof PET fabrics were prepared by the UV coating of UV-curable polyurethaneacrylate(PUA) formulation mixed with polyethyleneglycol(PEG) as a water soluble pore former. The dispersed PEG in the UV-cured coating was extracted by warm water, which can generate individual circular pores uniformly distributed all over the coating instead of pore channels. Accordingly the moisture permeability of the microporously coated fabrics increased substantially with increasing PEG addition without significant reduction of hydrostatic pressure. Also the silicone diacrylate addition in the formulation was beneficial in increasing the hydrostatic pressure. The UV-based microporous coating can be an alternative to conventional thermal curing of solventborne polyurethane coating owing to the enhanced environment friendliness and energy saving.

• Korean Journal of Plant Resources
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• v.27 no.4
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• pp.380-391
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• 2014

Plants as well as crops are damaged by a combination of the hot and dry winds that has been a major factor in the reduction of crop production. A means to protect them from damaging conditions is to consider a coating material. In this study, we established laboratory screening methods to find a coating material to protect a crop from rapid transpiration caused by various factors. In a test measuring the weight loss of kidney bean seedlings for 6 days, Avion treatments decreased its weight loss (P=0.05). Owing to long-time spend in completing this assay, we performed a more simple method using a cobalt chloride paper strip, which changes from blue to red colors under water condition. Beewax, guagum, paraffin liquid, soybean oil, and PE-635 gave a waterproofing effect above 37 and 43% at 0.5 and 1 h after treatment, respectively. However, these tested materials did not show significant waterproofing results at 2 h. Although the methods produced reasonable results, a screening method to obtain more objective data is needed. An alternative is to use an instrument that can detect the transpiration of crop leaves. In a preliminary test using barley leaves, a portable photosynthesis system showed transpiration inhibition of 2% soybean oil and 10 times-diluted Avion under field conditions. In another test using the leaves of maize seedlings and apricot tree, 2% liquid paraffin and plant oils such as apricot oil, linseed oil, olive oil, and soybean oil showed significant transpiration inhibition (P=0.05). Especially, paraffin liquid and soybean oil selected from above tests gave good transpiration inhibitory effects against rice at 2%. In addition, the mixture of 2% soybean oil and a spreader showed more elevated inhibition results comparing with soybean oil or the spreader alone indicating that the spreader may be attributed to more uniform diffusion of the hydrophobic material onto the leaf surface of maize seedlings. The hydrophobic material coated physically the stomata and cuticle layers on leaf surfaces of rice. These hydrophobic materials screened in this study are expected to be used as plant coating materials.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.169-176
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• 2010

Generally, poly-urea is widely used as waterproof coating material due to its superior adhesiveness, elongation capacity, and permeability resistance. In addition, it can be quickly and easily applied on structure surfaces using spray application. Since it hardens in about 30 seconds after application, its construction efficiency is very high and its usage as a special functional material is also excellent. However, currently, poly-urea is mostly used as waterproof coating material and the researches on its usage as a retrofitting material is lacking at best. Therefore, basic studies on the use of poly-urea as a general structural retrofitting material are needed urgently. The objective of this study is to develop most optimum poly-urea composition for structure retrofitting purpose. Moreover, the structural strengthening capacity of the developed poly-urea is evaluated through flexural capacity experiments on RC beams and RC slabs. From the results of the flexural test of poly-urea strengthened RC beam and slab specimens, the poly-urea and concrete specimen showed monolithic behavior where ductility and ultimate strength of the poly-urea strengthened specimen showed slight increase. However, the doubly reinforced specimens with FRP sheet and poly-urea showed lower capacity than that of the specimen reinforced only with FRP sheet.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2005.05a
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• pp.47-55
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• 2005

Fire extinguisher, which is cost effective and easily accessible, is a very effective way of fire suppression. To keep its initial performance it needs periodical inspection and appropriate maintenance. However, many fire extinguishers of which the powder is incompletely coated deteriorates due to the moisture and leak of charge pressure after several years. Accordingly inappropriate powder replacement and pressurization has widely been doing by unqualified persons. Also, the absence of lifetime for fire extinguisher made people keep old bad fire extinguisher without precise inspection. This study specified those issues through case studies and suggested some ways for the systematic improvement.

• Korean Journal of Human Ecology
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• v.9 no.1
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• pp.33-45
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• 2000

The handle were observed by objective and subjective method as the washing was repeated for 4 kinds(sample A, B, C, D) of materials which have different water vapor transmission, and the change of water vapor transmission each others. The results of factor analyses for 18 polar adjective words on subjective handle test yielded 4 factors, that were 'elastic property', 'surface property', 'thickness and weight property' and 'thermal and rigid property'. The surface properties were deteriorated remarkably as washing was repeated and significant difference were observed. Compared with the primary hand value for each materials, the statistical difference of samples was shown at Koshi and Fukurami measured by the KES-FB system. Koshi decreased for all the materials after repeated washing, and Fukurami had a tendency to increase for all the materials in proportion to repeated washing. Significant difference of total hand value wasn't shown in repeated washing number, but in fabric types.

• Journal of Powder Materials
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• v.21 no.3
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• pp.191-195
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• 2014

This study reports a simple way of fabricating the porous Cu with unidirectional pore channels by freeze drying camphene slurry with Cu oxide coated Cu powders. The coated powders were prepared by calcination of ball-milled powder mixture of Cu and Cu-nitrate. Improved dispersion stability of camphene slurry could be achieved using the Cu oxide coated Cu powders instead of pure Cu powders. Pores in the frozen specimen at $-25^{\circ}C$ were generated by sublimation of the camphene during drying in air, and the green bodies were sintered at $750^{\circ}C$ for 1 h in $H_2$ atmosphere. XRD analysis revealed that the coated layer of Cu oxide was completely converted to Cu phase without any reaction phases by hydrogen heat treatment. The porous Cu specimen prepared from pure Cu powders showed partly large pores with unidirectional pore channels, but most of pores were randomly distributed. In contrast, large and aligned parallel pores to the camphene growth direction were clearly observed in the sample using Cu oxide coated Cu powders. Pore formation behavior depending on the initial powders was discussed based on the degree of powder rearrangement and dispersion stability in slurry.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.292-292
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• 2013

최근, 자연의 기능성 표면을 모사하여 우리 생활에 응용하기 위한 연구가 활발하다. 초-발수 특성을 가지는 대표적인 예인 연꽃잎은 마이크로-나노 크기의 거친 미세돌기(papillae)를 가지고 있으며 그 위에 낮은 표면 에너지를 가지는 왁스(wax)가 발달 되어 항상 깨끗한 상태를 유지한다. 본 실험에서는 이를 모사하여 RIE (Reactive Ion Etching)방법을 이용하여 기판인 Poly silicon wafer를 Sf6가스를 사용하여 Metal mash로 거칠기를 만들어 주었고, RF-magnetron sputtering 장치를 사용하여 $6{\times}10^{-3}$ Torr의 진공도에서 낮은 표면에너지를 가지는 PTFE (polytetrafluoroethylene)를 증착하여 표면 구조와 발수특성에 대하여 조사하였다. SSME(Surface shape measurement equipment)측정결과 0.24~0.36 um RSa 값이 측정되었고, 12 uL의 Di-water로 접촉각을 측정 한 결과 RIE 10분 처리를 한 기판 위에 PTFE를 3분 증착하였을 때 가장 높은 $153^{\circ}$의 초-발수 특성이 나타났으며, 4주의 시간이 지났을 때에도 접촉각이 유지가 되었다. XPS 측정결과 초-발수 표면에서 나타나는 CF2와 CF3 피크 값이 측정되었다. Reactive Ion Etching을 이용한 PTFE 발수 특성은 방수, 스마트 윈도우, 자가세정(Self-Cleaning), 디스플레이 표시장치, 김서림 방지(Anti-Fogging), 대전방지 코팅 등에 다각적으로 응용 가능할 것이라 사료된다.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.58-58
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• 2011

CNT 나노기술을 응용한 IT산업용 적층간지용 ESD(정전방전, Electrostatic Dissipation)PU 발포필름의 제조 가공기술 및 상품화 개발은 전자제품 패키지에 요구되는 쿠션성과 정전방전 기능을 갖는 폴리우레탄 발포 필름의 제조기술을 확립함으로써 가능 할 수 있다. 특히 IT산업용 필름제품이 개발되면 ESD 성능을 발휘하게 됨으로서 정전기 쇼크에 의한 각종 전자제품의 오작동이나 파손 방지가 가능하게 되어 포장재, 자동차, 전자제품의 하우징 등으로 사용될 수 있게 된다. 현재까지 ESD 기능을 부여하기 위해서 사용되는 충전재로는 금속섬유, 금속플레이크, 탄소섬유, 카본블랙 등이 있으며, 최근 탄소나노튜브를 응용한 연구가 많이 진행되고 있는데 탄소나노튜브는 직경이 수십nm, 종횡비 1000이상의 나노섬유형태로 서 전기전도성이 구리수준으로 알려져 있고 소량을 충전할 시 기계적 특성도 오히려 증대하는 장점을 가지고 있으며 전기적 특성으로는 상대적으로 낮은 나노튜브 함량에서는 ESD를 들 수 있고 높은 함량에서는 전자파 차폐성까지 기대되고 있다. 본 연구에서는 우수한 인장강도, 기계적 강도, 열적 안정성, 내약품성을 가지면서 습식 또는 용융공정을 통해 용이하게 시트, 필름, 코팅제를 제조할 수 있는 방수, 투습방수성을 가지는 유연재료인 폴리우레탄(PU) 1액형 PU에 MWNT 함량이 3wt%인 IPA/MWNT 분산용액을 PU 함량 대비 20, 30, 40파트로 함유시켜 $120^{\circ}C$에서 2분 건조시켜 제조한 그라운드 필름에 2액형 PU와 IPA/MWNT 분산용액에 발포제를 첨가하여 발포온도 140, 150, $160^{\circ}C$에서 5분간 건조시켜 시료 필름을 제조하였다. 제조된 필름의 전기전도성 측정은 부피저항과, 표면저항을 각각 측정하여 확인하였으며, 필름의 마찰 대전압은 E.S.T-7 마찰 대전압 시험기를 이용하여 표면 마찰 대전압과 반감기를 측정하여 확인하고, 필름의 물리적 특성은 인장시험기를 이용하여 breaking stress, breaking strain을 구하였다. 필름의 표면 특성은 영상 현미경 시스템을 사용하여 ${\times}1000$ 배율로 측정하여 분산특성과의 연관성을 확인하였다.