• 한국건축시공학회지
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• 제15권6호
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• pp.579-587
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• 2015

자기치유성능을 가지고 있는 자기치유제를 함유하고 있는 마이크로 캡슐을 콘크리트 표면의 고분자 매트릭스층에 적용하였다. 메타크릴레이트를 코어물질로 하고 폴리 우레아포름알데히드를 캡슐막 구성물질로 하는 미세캡슐을 고분자 매트릭스 안에 첨가하여 콘크리트 표면에 코팅하였다. 콘크리트 표면에 미세균열이 형성되고 전파될 때, 균열이 전파되는 위치에 있는 캡슐이 파괴되어 치유체가 균열면 사이로 흘러나오게 되고, 균열에 스며든 단량체가 햇빛에 의해 중합반응을 일으켜 균열이 자기치유 되는 현상을 고찰한다. 자기치유성능평가는 흡수성, 투수성 실험 및 광학현미경을 통한 관찰로 확인하였다. 결과적으로 제시된 자기치유시스템은 콘크리트 균열부의 부분적인 복원을 위해 사용할 수 있음을 확인하였다.

• 한국추진공학회지
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• 제23권4호
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• pp.92-97
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• 2019

추진제, 라이너 그리고 내열재간의 접착력을 향상시키기 위한 연구를 수행하였다. 내열재에 아무런 처리하지 않은(Bare) 상태보다는 피막처리제를 적용한 것이 접착력 향상에 유리하였다. 라이너 도포 두께가 증가할수록 내열재와 추진제간의 접착력이 향상되는 것을 확인하였으며, 라이너 경화는 24시간 경화 시간이 필요하며, 그 이상의 과경화는 접착력에 불리한 영향을 끼친다. 또한 결합제를 적용할 때가 적용하지 않을 때보다 접착력에 유리하다는 것을 알 수 있었으며, 결합제 함량이 증가할수 록 접착력도 상승하였다. 결합제 종류에 따른 접착력 변화는 HX-868이 HX-752보다 접착력이 소폭 향상되었다.

• 한국응용과학기술학회지
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• 제17권1호
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• pp.7-13
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• 2000

Quater polymer(MBHA) containing two types of acrylic functional group, acetoacetoxyethyl methacrylate(AAM) and 2-hydroxyethyl acrylate was prepared. Then, the MBHA was blended with polyisocyanate type Desmodur IL as a curing agent. Thereafter the mixture was cured at room temperature to get high solid acrylic/polyisocyanate. The MBHA was synthesized at $150^{\circ}C$ for 6 hours typically, and the final conversion reached 87-88%. Lowering Tg and increasing AAM amount in the MBHA resulted in high value of conversion. There was no difference in conversion with the variations of OH values. From the results of physical property tests, MIHS coating was proved to be a good automotive top-coating material.

• 한국응용과학기술학회지
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• 제24권2호
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• pp.167-173
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• 2007

The surface of poly(ethylene naphthalate) film applicable to high temerature insulator for convection microwave oven was modified with silicone coating solutions in the presence of silane crosslinking agent. The structure and properties of the PEN films were investigated by using Fourier transform IR spectroscopy, viscometry, microscopy, and tensile tests. The experimental results showed that the coating with silicone enhanced thermal stability up to $200^{\circ}C$, and slightly lowered the tensile strength and elongation of the PEN films. Judging from dimensional stability results the silicone coated PEN films can not be used for higher temperature insulator above $230^{\circ}C$. Serious dimensional contraction of films was obtained during heat treatment at $250^{\circ}C$ even for 1h. However, the surface of those films still have same chemical structure of silicones. Therefore, If we use PEN film prestretched at $230^{\circ}C$ as base one it will be possible to prepare a high temperature insulator up to $230^{\circ}C$. Conclusively, a silicone coated PEN film can be suitable for the application to convection microwave oven door insulator at high temperature up to $230^{\circ}C$.

• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.424-431
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• 2009

Treatment for water repellency on the carbon supports of GDL which composed a part of MEA has been suggested as a solution to prevent flooding. PTFE is a fluoropolymer that has hydrophobic property and a PTFE emulsion was selected as waterproof agent in this investigation. Carbon paper was coated by PTFE emulsion with different particle size of 5~500 nm and 3~$5\;{\mu}m$ as various concentration. PTFE coated carbon paper has difference in weight variation changed proportionally at PTFE concentration and coating times. Then gas permeability of the coated carbon paper with emulsion of 3~$5\;{\mu}m$ PTFE was changed vastly. Characteristics of carbon paper coated with different PTFE emulsion were analyzed by FE-SEM, FT-IR spcetroscopy and were evaluated by weight variations, gas permeability and water contact angle.

• 한국세라믹학회지
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• 제31권7호
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• pp.795-803
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• 1994

Ferroelectric BaTiO3 thin film was produced using BaTi-ethoxide sol. This sol was prepared from BaTi-ethoxide by a partial hydrolysis with ammonia as a basic catalyst and ethylene glycol as a chelating agent. BaTiO3 thin film was prepared from three continuous spin-coating layers of the sol on bare Si(100) wafer at 2500 rpm followed by pyrolysis at $700^{\circ}C$ for 30 min. After the heat treatment, the film was 0.200$\pm$0.010 ${\mu}{\textrm}{m}$ thick and its grain size was 0.059 ${\mu}{\textrm}{m}$. On the other hand, electrical properties were measured for BaTiO3 thin film separately prepared on Au-deposited silicon wafer. The dielectric constant and loss of the BaTiO3 thin film at room temperature was 150~160 and 0.04 respectively, which was measured at 10 kHz and oscillation level of 0.1 V. In the measurements of the dielectric properties at high temperatures, it was observed that the capacitance of the thin film increases steeply, while the dielectric loss reaches maximum around 1$25^{\circ}C$, which corresponds a phase transition from tetragonal to cubic BaTiO3.

• 한국응용과학기술학회지
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• 제28권3호
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• pp.335-344
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• 2011

The pearlesent pigment has received attention in a diversity of fields like cosmetics, inks, paints and so on. Ferric Ferrocyanide, one of the nano sized pearlescent pigment, is a kind of surface modification pigment that covers a metal oxidized substance or a coloring agent with uniform thickness. Characteristics of pearlescent pigment are various interference color, intense gloss effect and a three-dimensional effect. We synthesised the pearlesent pigment that ferric ferrocyanide can be deposited on the titania/mica surface by hydrothermal synthesis method. The process parameters are concentration of precursor, controlling pH and reaction temperature. The optimun conditions is that amount of iron(III) chloride hexahydrate is 3.1 wt% and amount of potassim ferrocynide trihydrate is 3.6 wt% in the started pH 4.5 at $70^{\circ}C$. The coating rate and coating efficiency of ferric ferrocyanide was about 1.47 % and 96.7 %, respectively. The synthesised pearlesent pigment was characterized by SEM, XRD, FT-IR and EDS.

• 한국표면공학회지
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• 제41권6호
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• pp.312-324
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• 2008

In this study, the functional property as a super abrasive material was secured for CBN powder by the electroless Ni-P plating on the surface of the particle. The plating solution has been prepared to control the surface morphology by regulating surfactants and process conditions. The effects of processing parameters on the surface morphology of CBN powder was discussed. The results are summarized as follows; A stable plating tendency was achieved from 1 hour after quantitatively dropping reducing agent. It was observed that more than 50% of the weight gain was obtained by Ni-P coating on the surface of CBN super abrasive powder. The morphology of the Ni-P coating layer is consisted of botryoidal and spiky type and it could be controlled by regulating processing parameters. Superior characteristic in terms of surface morphology was found in the nonionic surfactant XL-80N. It was found that XL-80N considerably decreased surface tension of CBN powder and Ni-P alloy surface then enhance wettability as well as plating rate. Metal coated CBN powder as a raw material of resin bond wheel has been developed through this investigation.

• 한국재료학회지
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• 제17권4호
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• pp.185-191
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• 2007

The purpose of this study is to evaluate the thin fihn dielectric made of hybrid sol, which consist of barium titanate powder, polymeric sol and other polymers. This sol will be used dielectric applied to small, thin electric passive components such as MLCC(Multi Layer Ceramic Condenser), resister, inductor. This sol is composed of mixed fine barium titanate powder and polymeric sol including Ba, Ti-precursor, solvent, chelating agent, chemical reaction catalyst, the additive sols to improve fired densification and temperature reliability. First at all, we mixed hybrid sol to be dispersed and be stabilized by ball milling for 24hrs. By spin coating method, we makes thin film dielectric on the convectional green sheet for MLCC. After heat treatments, we analyzes the structure morphology, physical, electrical properties and X5R Temperature properties.

• 한국전기전자재료학회논문지
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• 제26권3호
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• pp.221-226
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• 2013

The water soluble quantum dots (QDs) are synthesized by the phase transfer and silica coating reaction. The photoluminescence intensity of silica-coated QDs are mainly affected by the amount of phase transfer agent, SDS (sodium dodecyl sulfate), and the maximum value is obtained at the cmc (critical micell concentration) concentration of SDS in the phase transfer reaction. Based on fluorescence spectra and field emission transmission electron microscope (FETEM), the energy transfer rate by forster resonance energy transfer (FRET) is increasing with the thickness of the silica shell coated on CdSe/ZnS QDs.