• 한국정밀공학회지
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• 제24권12호
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• pp.119-127
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• 2007

Recently, microstructures fabricated using microstereolithography technology have been used in the biological, medical and mechanical fields. Microstereolithography can fabricate real 3D microstructures with fine features, although there is presently a limited number of materials available for use in the process. Deformation of the fine features on a fabricated microstructure remains a critical issue for successful part fabrication, and part deformation can occur during rinsing or during fabrication as a result of fluid flow forces that occur during movement of mechanical parts of the system. Deformation can result in failure to fabricate a particular feature by breaking the feature completely, spatial deflection of the feature, or attaching the feature to neighboring microstructures. To improve mechanical strength of fabricated microstructures, a clay nanocomposite can be used. In particular, a high-aspect ratio microstructure can be fabricated without distortion using photocurable liquid resin containing a clay nanocomposite. In this paper, a clay nanocomposite was blended with a photocurable liquid resin to solve the deformation problem that occurs during fabrication and rinsing. An optimal mixture ratio of a clay nanocomposite was found through tensile testing and the minimal allowable distance between microstructures was found through fabrication experimentation. Finally, using these results, high-aspect ratio microstructures were fabricated using a clay nanocomposite resin without distortion.

• Elastomers and Composites
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• 제26권4호
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• pp.296-303
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• 1991

Surface of crystalline silica was sequentially reacted with silane(A 187), liquid $rubber(CTBN{\times}8)$, and vinyl monomer(GMA) in existence of TEA(triethylamine) or BPO(benzoyl peroxide). It was mixed with epoxy resin at a ratio $0{\times}60%$ (vol. % ) of total component. For mixtures, viscous properties were investigated experimentally. 1) Coating ratio depended on pH of mixture and quantity of catalyst. 2) Treated silica represented lower viscosity than untreated. 3) Thixotropic index represented best at silica_content $15{\sim}23%$ and showed more large deviation over $120^{\circ}C$. 4) Relative viscosity followed kernel's at $0{\times}10%$ of silica content and get out of Mooney's at more than 15%.

• 대한토목학회논문집
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• 제35권2호
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• pp.465-470
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• 2015

에폭시 아스팔트 혼합물은 에폭시 수지와 경화제의 화학반응이 진행되어 양생시간을 거쳐 성능 발현이 이루어진다. 에폭시 아스팔트의 양생수준은 후속공정의 진행과 교통개방 및 공정계획의 수립에 절대적인 영향을 미치므로 정확한 예측모델의 개발이 중요하다. 본 연구에서는 기존 예측식에 사용되는 인자들의 화학적 의미 분석을 통하여 에폭시 수지의 농도와 경화특성을 반영하여 기존식보다 확대된 적용 범위를 갖는 양생수준 예측식을 제시하였다. 실외양생 실험과 비교 결과 상관계수가 0.971 이상으로 나타나 조성이 다른 에폭시 아스팔트 혼합물의 온도와 시간에 따른 양생수준을 예측할 수 있는 것으로 나타났다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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• pp.47-52
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• 2000

F.R.P specimens were made by mixture CM(chopped mat) 450-104 matrix & RC(roving clothes)570-100 Roving, the mixture ratio Resin: hardener (92:8) for tensile test. It was also made of plates by hand lay-up method and was been cured for 24 hours and then was cut tensile specimens in accordance with ASTM D638 Type 3. Knowing exact behavior of bonded area's stress and strain when the tensile test was going on, the test specimens were made of 2 plies laminae of F.R.P in each for supporting cut part in middle of specimen length. And in middle part also were covered of F.R.P plies of 1/2, 2/3 length of specimen in each as well. Also we consider shear stress in adhered area. This study reveals that as plys length is more longer, rupture stress grows remarkably larger.

• 콘크리트학회논문집
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• 제19권4호
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• pp.421-431
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• 2007

본 연구의 주 목적은 유리 및 탄소단섬유 (chopped fiber)와 에폭시 및 비닐에스터수지 (resin)를 외기에서 혼합하여 요철이 많은 콘크리트 표면에 고속의 압찰 공기로 랜덤하게 분사하여 기존 콘크리트 구조물을 보강하는 새로운 공법, 즉 sprayed FRP 보수보강 공법을 개발하는 것으로서, 본 연구에서는 sprayed FRP 보강을 위한 치적의 재료 물성치를 제시하고자 유리 및 탄소단섬유의 길이, 단섬유와 에폭시 및 비닐에스터수지의 배합 비율 등을 주요변수로 설정하여 재료 인장시험을 실시하였다. 또한 상기 재료 시험 결과를 바탕으로 sprayed FRP 공법을 이용하여 보강된 철근콘크리트 휨 보, 전단 보 및 손상 보의 보강 성능을 실험적 연구를 토대로 평가하였다. 그 결과, 유리 및 탄소단섬유의 길이 38 mm, 섬유와 수지의 배합 비율 1 : 2가 최적 물성치로 제안되었으며, sprayed FRP의 휨 및 전단 보의 보강 효과는 기존 FRP sheet와 유사한 보강 효과를 나타냈으며, 손상 보의 경우 최대 강도의 결과를 비교해보면 보강 보와 동등한 보강 효과가 나타났다. 기존 FRP 설계식의 적용 가능성을 분석해본 결과, sprayed FRP 휨실험체의 경우 기존설계식의 적용이 가능한 것으로 드러났으며, 전단실험체의 경우는 전단강도 저감계수 ${\alpha}=0.18$이 실험값과 근접한 범위 내에서 안전 측으로 설계가 되는 것으로 사료된다.

• 자원리싸이클링
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• 제17권5호
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• pp.19-27
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• 2008

국산무연탄과 페놀수지를 혼합 소성하여 성형코크스를 제조하고 점결제의 량, 탈수온도 및 시간, 경화온도 및 시간, 소결온도 및 시간, 무연탄의 입도 및 입도 분포, 무연탄의 품위, 플라스틱 혼합율 등을 변화시킬 경우에 있어서 제조되는 코크스의 기공율, 전기 저항률 등의 물성 변화를 연구한 결과 제조된 대부분의 코크스는 $0.3\sim1.2\Omega{\cdot}cm$의 전기저항률과 $10\sim30%$의 기공율 범위에서 각 인자의 영향을 받아 변화함을 확인하였다.

• 공업화학
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• 제1권2호
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• pp.116-123
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• 1990

감광성 orthonaphthoquinonediazide-sulfonyl 유도체를 합성하고, 그 감광특성에 대해 검토한 결과, UV에 의해 광변환 되어, 알칼리 가용성의 분해화합물이 생성됨을 확인하였다. 이 유도체를 PAC로, m-cresol novolac을 matrix resin으로 photoresist를 제조하고 감광 특성을 고찰하여, 미세 패턴용 photoresist로의 타당성을 확인하였다. 3, 4, 5-Trihydroxybenzophenone 의 벌키한 공명 구조는 노광부의 감도와 가용성을 향상시켰으며, PAC 와 matrix resin의 혼합 무게비가 3:8 일 때 가장 적절한 dissolution rate를 나타냈으므로, 이 photoresist가 정해진 조건 하에서 감도, 해상력이 가장 우수하였다.

• 한국환경과학회지
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• 제17권2호
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• pp.211-224
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• 2008

Characteristics of the esterification reaction between free fatty acid in rice bran oil and methanol was investigated in the presence of catalysts, such as PTS(p-toluene sulfonic acid), Amberlyst 15 dry and SCX(silica gel based strong cation exchange resin). While reaction temperature was kept constant at $65^{\circ}C$, initial feed content of free fatty acid was varied from 100% to 1% by addition of pure free fatty acid which was previously made from rice bran oil. Also, the effect of mole ratio of methanol to fatty acid on the final conversion was examined. When esterification of pure free fatty acid was catalyzed by several acids, final conversions were increased in order of Amberlyst 15 dry, SCX and PTS. Using PTS catalyst, initially the reaction proceeded in homogeneous 2nd oder reaction mechanism. However, phase of reaction mixture changed from homogeneous to heterogeneous along the reaction time and then reaction rate was retarded by mass transfer resistance of methanol. Final conversion of free fatty acid in reaction mixture was depended on initial feed content of free fatty acid, and had maximum value at 30% of initial feed free fatty acid content for all kinds of catalysts used. And the final conversion was increased with mole ratio of methanol by the improvement of reaction rate. When initial feed free fatty acid content below 10% and the reaction was catalyzed by PTS, concentration of free fatty acid in reaction mixture was increased in the middle of reaction time by hydrolysis of triglyceride in reaction mixture. Also, if silica gel was added into the reaction mixture which had initial feed free fatty acid content below 50%, final conversion was increased by the adsorption of moisture produced. The SCX catalyst made the esterification reaction of free fatty acid to progress like in case of PTS catalyst. However, when initial feed free fatty acid content below 10%, concentration of free fatty acid in. reaction mixture was decreased monotonically and not increased in the middle of reaction time on the contrary to the case of PTS. Thus, SCX catalyst accomplished more high value of final conversion than PTS catalyst for the initial feed fatty acid content range from 50% to 5% In case of initial feed free fatty acid content of 1% and mole ratio of methanol was 2, concentration of free fatty acid in reaction mixture increased over the initial feed free fatty acid content for all kind of catalysts used. Although SCX catalyst was added into reaction mixture which had 1% of initial feed fatty acid content, final conversion was hardly raised by mole ratio of methanol.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.33-38
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• 2007

This paper reports an attempt to develop 7-wire steel tendon which is instrumented with optical FBG sensors. The tendon is devised to replace the king cable, which is located in the center of the tendon, by a steel tube in which the FBG sensor are attached along the hole using a high-mobility polyester resin. The circular steel tube has typical of 5 mm outer diameter and 1 mm inner diameter, and can easily be manufactured by means of an pultrusion process. Using the tube, in this study, three different types of one meter-long smart tendons are fabricated depending on mixture ratio of polyester resin and initiator. The performance of the FBG sensors as well as mechanical characteristics of the prototype are tested through the tensile test. Test results shows that the proposed smart tendon is in principle very effective for measuring the working strain of the tendon.

• 조명전기설비학회논문지
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• 제17권2호
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• pp.95-101
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• 2003

본 논문에서는 모의 GIS를 에폭시로 코팅하고, 금속이물 혼입시의 부분방전, 부상전압, 절연파괴전압 등을 측정하여, 코팅하지 알았을 경우와 비교 분석하였다. 또한, 여러 경우의 절연사고를 모의하기 위해, SF$_{6}$/$N_2$가스 혼합비, 금속이물의 재질, 직경, 코팅두께, 압력 등을 변화시키면서 전기적특성을 관찰하였다. 실험결과, 코팅두께가 증가할수록 부분방전개시전압이 증가하였으며, 부분방전의 크기는 감소하였다. 또한 철합금 파티클의 부상전압이 구리파티클보다 높았으며, 직경이 증가할수록 부상전압도 증가하였으며, 코팅두께가 두꺼워질수록 절연파괴 전압이 증가하였다. 이상의 연구결과 GIS를 에폭시로 코팅함으로써 절연성능을 향상시킬 수 있음을 확인하였다.