• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.159-159
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• 2009

We characterize a flexible self-assembled liquid crystal display (LCD) fabricated from a polyimide (PI) alignment layer with polydimethylsiloxane pixel walls. Ion beam (IB) irradiation aligned LC molecules in the PI layer and bonded two flexible plastic substrates in a one-step assembly of the pixel walls. X-ray photoelectron spectroscopic analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy provided chemical and physical evidence for the formation of stable chemical bonds between the PI layer and the PDMS pixel walls in addition to the important maintenance of a uniform 6 um gap between the two substrates without the use of any epoxy resins or other polymers.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.349-352
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• 2007

Asphalt overlay resurfacing techniques have been widely utilized in maintaining asphalt concrete in Korea, causing severe traffic congestions while being in construction and difference in level due to the repeated overlay. Besides on these technical difficulties, there have been financial disadvantages associated with technique, mainly because overlay method has been executed for pavements with intact foundations, which is contrary to the norm. This study is aiming to increase the expected life length of the asphalt pavement up to the endurance period, to raise the efficiency of the pavement by maximizing the social benefit and to enhance public character of the street through combining ceramics with epoxy resins, which has advantages in compatibility with the existing pavement materials, durability to abrasion and endurance. It has been expected that the adoption of new method and pavement materials to the actual work sites will develop the performance of the pavements, and to lengthen the durability of the existing materials. The other advantages of the 'thin surfacing' method could be the improved adhesiveness, waterproof, corrosion-proof and bending strength.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.185.3-186
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• 2003

It is well-known that bisphenol A(BPA), an industrial raw material for polycarbonate and epoxy resins, shows estrogenic activity. Recent research from our laboratory has shown that SPA disrupts interaction between thyroid hormone and its receptor in a non-competitive manner, and alters the thyroid-hormone dependent expression of growth hormone(GH) and prolactin(PRL). (omitted)

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.10
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• pp.735-741
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• 2007

An axial F.R.P. fan model for cooling tower is developed. The fan is designed using the equations for one dimensional inviscid flow through the fan blade. Fan shape is swept forward with a parabolic function. Calculations of the three dimensional turbulent flow around the fan are carried out to investigate performance of the fan. Data of the total pressure rise and hydraulic efficiency can be obtained for the various setting angles. Calculated values of the total pressure rise and hydraulic efficiency at the design point are less than those of the design specification. The prototype of the F.R.P. fan is made by laminating of the fiberglass and epoxy resins on the mold of fan shape.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.172-176
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• 1999

에폭시 수지의 강인성 향상을 위하여 양말단에 아민 반응기를 가지는 PES-CTBN-PES triblock copolymer를 합성하여 이를 에폭시 수지의 강인화제로 사용하였으며 경화제로는 p-DDS(p-dichlorodiphenylsulfone)를 사용하였다. 또한 공중합체에 의한 물성 향상효과를 CTBN과 PES-NH$_2$의 블렌드에 의한 경우와 비교하였다. 강인화된 에폭시 수지의 물성은 강인성 및 굴곡특성을 측정하여 분석하였으며, 열특성은 DSC, TGA, 및 DMA에 의해 실시되었다. 그리고 강인화된 에폭시 수지의 강인성 향상 mechanism을 규명하기 위하여 파단면을 SEM으로 분석하여 상분리 거동을 고찰하였다. 높은 유리전이온도와 우수한 기계적 물성을 가지는 고성능 기능성 폴리설폰(PES-NH$_2$)과 상용 액상 고무 첨가제인 CTBN을 이용하여 합성된 공중합체를 강인화제로 사용함으로써 열안정성, 탄성률 및 내식성의 감소없이 에폭시 수지의 쳐대 단점인 강인성을 최적 수준으로 개선시킬 수 있었으며 공중합체의 에폭시 수지에 대한 우수한 용해도에 따른 가공성이 향상되었다.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.579-584
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• 2003

For strengthening deteriorated concrete structures, externally bonded FRP sheets or plates using epoxy resins are widely used. For the external FRP composites to be effective in improving the performance of the structure, bond between FRP composites and concrete is required. In general, the most frequently observed failure mode in FRP strengthened concrete structures is debonding failure at the interfacial section between FRP and concrete. Therefore, it is very important to find out the interfacial behavior properties. This paper presents experimental results of the relationship of concrete and FRP sheet for some conditions including concrete compressive strength, concrete surface preparation to observe the bond behavior between concrete and FRP sheet and various anchorage types to increase the bond capacity of FRP sheet.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.05a
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• pp.67-69
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• 1988

In this study, after changing the curing condition of hardner(DDM) and filler($SiO_2$) contents dielectric and dynamic mechanical properties were studied according to the variation of temperature. As the result we obtained a correlative $\alpha$-peak at 125-150[$^{\circ}C$] from dielectric and mechanical properties. With increasing curing condition and filler contents both dielectric and internal friction loss were, decreased, peak temperature shifted to high temperature, but there was no variation on peak temperature with filler contents. As the above result we knew the correspondence between dielectric and mechanical characteristics.

• Environmental Analysis Health and Toxicology
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• v.19 no.3
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• pp.251-259
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• 2004

Xenoestrogens are chemicals with diverse structure that mimic estrogen. Bisphenol A, a monomer of polycarbonate and epoxy resins, has been detected in canned food and human saliva. Bisphenol A stimulate cell proliferation and induce expression of estrogen -response genes in vitro. The purpose of the this study was to evaluate cell proliferation of bisphenol A in the presence of a rat liver 59 mix contaning cytochrome P450 enzymes and Cu (II). The fragmentation of intact DNA, a parameter of apoptotic cell death, was evaluated quantitatively by diphenylamine reaction method. Bisphenol A induced apoptotic cell death in a dose-dependent manner The effect of radical scavenger on the apoptotic cell death induced bisphenol A was investigated. The DNA fragmentation induced by bisphenol A was significantly inhibited by addition of radical scavenger to the culture medium. This indicated that elevated oxidative stress caused by imbalance between the production and removal of free radicals occurred in cells. Taken together, these results suggest that free radical reacts with Cu (II) leading oxidative stress.

• Environmental Analysis Health and Toxicology
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• v.18 no.3
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• pp.175-182
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• 2003

Bisphenol A shares similarities in structure, metabolism and action with DES, a known human teratogen and carcinogen. Bisphenol A, a monomer of polycarbonate and epoxy resins, has been detected in canned food and human saliva. The purpose of the this study was to evaluate the cytotoxicity, cell proliferation of bisphenol A In the presence of a rat liver S9 mix, contaning cytochrome P450 enzymes, and Cu (II). In the present study, Bisphenol A in combination with Cu (II) exhibited a enhancement in cytotoxicity which were inhibited by free radical scavengers. The content of malondialdehyde, an end product of lipid peroxidation, was also found to increase with concentration of bisphenol A. Also, we examined the change of CuZn-SOD, Mn-SOD, catalase and GPx activities in the MCF-7 cells exposed to bisphenol A. The activities of CuZn-SOD, CPx, catalase were found to decrease with bisphenol A concentration. Meanwhile, the activity of Mn-SOD was unchanged. This indicated that elevated oxidative stress caused by imbalance between the production and removal of free radicals occurred in cells.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.200-206
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• 1992

The effect of fiber diameter and gauge length on pull-out test for the interfacial properties in fiber reinforced resin composites have been investigated and these results have been arranged as statistical analysis. The fiber and matrix resins used for this study were stainless steel fiber (SUS316) and carbon fiber (high strength type), epoxy and high density polyethylene resin. From this study, it has been found that shear strength are constant regardless of gauge length of pull-out test and coefficient of variation depend on fiber diameter. In addition, it has been found that the interfacial shear strength decreased with the increasing fiber diameter, and in all case, Weibull parameter (m) has approximately 1.2/C.O.V.