• 한국인쇄학회:학술대회논문집
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• 한국인쇄학회 2001년도 국제학술발표회
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• pp.127-134
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• 2001

• 한국정밀공학회지
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• 제27권3호
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• pp.135-141
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• 2010

Researchers continue to explore possibilities for expanding additive manufacturing (AM) technologies into direct product manufacturing. One limitation is in the materials available for use in AM that can meet the needs of end-use applications. Stereolithography (SL) is an AM technology well known for its precision and high quality surface finish capabilities. SL builds parts by selectively crosslinking or solidifying photo-curable liquid resins, and the resin industry has been continuously developing new resins with improved performance characteristics. This paper introduces a unique SL machine that can fabricate parts out of multiple SL materials. The technology is based on using multiple vats positioned on a rotating vat carousel that contain different photo-curable materials. To change the material during the process, the build platform is raised out of the current vat, a new vat with a different material is rotated under the platform, and the platform is submerged into the new vat so that the new material can be used. This paper introduces a new vat exchange mechanism, cleaning process, recoating process, resin leveling mechanism and process planning technologies for the implementation of multiple material SL. An overview of the system framework is provided and the system integration and control software is described. In addition, several multiple material test parts are designed, fabricated, and described.

• Elastomers and Composites
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• 제47권4호
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• pp.318-328
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• 2012

본 연구에서는 blocked isocyanate와 하이브리드 기술을 이용해서 1액 경화형 폴리우레탄 탄성체를 제조하였다. 1액 경화형 하이브리드 폴리우레탄의 제조를 위해서 hydroxyl group을 포함하는 실리카 하이브리드를 합성하고 입자크기, 형태 및 탄성체 내의 하이브리드 입자분포를 확인하였다. 또한, 열해리특성, 기계적 물성, 성형특성을 조사하였다. 1액 경화형 폴리우레탄 탄성체의 열해리 특성을 평가한 결과 온도가 높을수록, 열처리 시간이 길어질수록 blocking된 isocyanate의 해리가 더 잘 진행되었다. 합성된 실리카 하이브리드는 직경이 23~27 nm이고 구형이었으며 하이브리드 폴리우레탄의 단면을 FE-SEM과 EDS를 사용해서 분석한 결과 하이브리드 입자가 폴리우레탄 분자구조 내에 잘 분산되어있는 것을 확인하였다. 하이브리드 폴리우레탄의 경우에는 하이브리드를 포함하지 않는 폴리우레탄 탄성체에 비해 기계적물성, 내마모성 및 열적특성이 향상되었으며 가소제를 사용하는 경우에는 물성의 변화가 거의 없는 것으로 확인되었다.

• Macromolecular Research
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• 제14권5호
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• pp.517-523
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• 2006

The effects of particle content, size and shape on the thermal conductivity (k) and adhesion properties of thermally conductive, pressure-sensitive adhesives (PSAs) were investigated. The matrix resins were thermally crosslinkable, 2-ethylhexyl acrylic polyol and ultraviolet (UV)-curable, random copolymer consisting of acrylic oligomer and various acrylates. We found that k increased with increasing diameter and particle aspect ratio, and was further enhanced due to the reduction of the interfacial thermal barrier when the coupling agent, which increases the adhesion between particles and the matrix resin, was used. On the other hand, adhesion properties such as peel strength and tack of the thermally crosslinkable resin decreased sharply with increasing particle content. However, for UV curable resin, increased particle addition inhibited the decrease in adhesion properties.

• 한국전기전자재료학회논문지
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• 제29권12호
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• pp.819-823
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• 2016

DSSC (dye-sensitized solar cell) is expected to be one of the next-generation photovoltaics because of its environment-friendly and low-cost properties. However, commercialization of DSSC is difficult because of the electrolyte leakage. We propose thermal curable base on silicon resin and apply a unit cell and large area ($200{\times}200mm$) dye-sensitized solar cell. The resin aimed at sealing of DSSC and gives a promising resolution for sealing of practical DSSC. In result, the photoelectric conversion efficiency of the unit cell and the module was 6.63% and 5.49%, respectively. In the durability test result, the photoelectric conversion efficiency of the module during 500, 1,000, 1,500 and 2,000 hours was 0.73%, 0.73%, 1.82% and 2.36% respectively. It was confirmed that the photoelectric conversion efficiency characteristics are constant. We have developed encapsulation material of thermal curing method excellent in chemical resistance. A sealing material was applied to the dye-sensitized solar cell and it solved the problem of durability the dye-sensitized solar cell. Sealing material may be applied to verify the possibility of practical application of the dye-sensitized solar cell.

• 한국정밀공학회지
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• 제25권1호
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• pp.130-137
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• 2008

Two-photon stereolithography (TPS) is recognized as a useful process for the fabrication of three-dimensional microstructures. Recently, the need for a two-photon curable resin with high strength increases as 3-D moicrostructures of high aspect ratio or large scale of several hundreds micrometers are required for applications of nano/micro devices in IT/BT. In this work, process parameters of TPS employing the SU-8 which is a representative two-photon curable resin with high strength have been studied for the precise fabrication of 3-D microstructures with high strength. The pre-baking and post-baking processes are studied and the parameter study of the SU-8 in TPS is conducted. Through this work, very small roughness of 12 nm and the minimum aspect ratio of ${\sim}1$ which provides a precise accumulation of layers could be obtained. Using the conditions studied in this work, some 3-D examples are fabricated.

• 폴리머
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• 제36권4호
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• pp.531-535
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• 2012

폴리아닐린(PANI) 나노섬유를 전도성 충전제로 사용하여 광경화형 전도성 투명필름을 제조하였다. 화학산화중합(chemical oxidation polymerization)으로 나노섬유 구조의 산화형 폴리아닐린(ES-PANI)을 합성하였다. ES-PANI는 디도핑을 통해 환원형 폴리아닐린(EB-PANI)으로 유도하였다. 이것을 전도성 충전제의 전구체로 사용하여 도데실벤젠설폰산(DBSA)이 포함되어 있는 광경화형 레진에 분산시키면 재도핑된 재산화형 폴리아닐린(rES-PANI)을 얻을 수 있었다. 이런 과정을 통해 나노섬유 형태가 유지되면서 높은 전도성과 분산안정성이 우수한 광경화형 전도성 레진용액을 제조할 수 있었다. 제조된 광경화형 전도성 레진용액은 상온에서 3달 정도 두어도 rES-PANI 충전제의 침전물이 생기지 않았다. 또한 이 용액을 폴리(메틸 메타크릴레이트)(PMMA) 기재 위에 스핀코팅 후 광경화하여 약 $5{\mu}m$ 두께의 전도성 투명필름을 제조하였다. rES-PANI 나노섬유 농도가 1.4 wt%일 때 표면저항 $6.5{\times}10^8{\Omega}/sq$, 550 nm 파장에서 91.1%의 투과도를 보였다. ES-PANI의 디도핑-재도핑(dedoping-redoping) 과정을 통해 광경화형 전도성 레진용액에 분산된 PANI는 농도에 따라 필름표면저항과 광학적 투명도를 조절할 수 있는 대전방지 보호필름을 제작하는 새로운 방법을 제시하였다.

• 폴리머
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• 제36권4호
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• pp.536-541
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• 2012

실리카 입자가 첨가된 광경화성 임프린트용 복합체를 제조하여 실리카 양에 따른 경화 특성과 전사된 수 백 나노미터 크기의 임프린트 패턴 형성에 관한 결함을 조사하였다. 상온에서 UV 경화한 임프린트 레진은 실리카 양이 증가할수록 탄성률이 커지고 수축률이 줄어드는 것을 알 수 있었다. 그러나 실리카 입자의 양이 7 wt% 이상인 경우 전사된 나노기둥끼리 서로 달라붙는 결함을 보이는데, 이는 실리카 입자가 광반응을 방해하여 임프린트 레진의 경화가 불완전하게 되면서 광경화된 레진의 점성이 증가했기 때문이다. 임프린트 레진에 실리카 입자를 충전제로 사용하면 경화 후 나노 패턴의 강도를 증가하여 형태를 유지하는데 도움이 되지만, 실리카 양이 7 wt% 이상이 되면 오히려 광반응 전환율이 떨어져 임프린트 공정에 의한 나노 패턴의 전사가 어려운 것을 알 수 있다.

• Tribology and Lubricants
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• 제14권4호
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• pp.72-78
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• 1998

In this work, the effects of binder materials on the tribological behavior were experimentally evaluated for air curable MoS$_2$bonded film lubricants. The binders tested were basically alkyd and acryl based resins, and also were modified by nitro-cellulose in various weight percentages. Effects on the binder ratio to solid lubricants and the molecular weight of binders were also investigated in all aspects of the tribological behavior. For the tests, LFW-1 and Falex tester were used to measure mainly the endurance life and load carrying capacity of bonded lubricants. Results showed that lubricants of methacrylic resin has the better performance than those of other resins, and also the properties of lubricants both of alkyd and acrylic resins could be improved by modification with nitro-cellulose. It was also shown that the optimum ratio of nitro-cellulose related closely to the binder material and the testing machine.

• Macromolecular Research
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• 제15권6호
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• pp.560-564
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• 2007

The photostabilization and cure kinetics of UV-curable, optical resins containing various formulations of photostabilizers were investigated to determine the system with the highest cure conversion and durability. Photo-DSC analysis revealed that increasing the concentration of a UV absorber (UVA) decreased both the crosslink density and the cure rate due to competition for the incident photons between the photoinitiator and the UVA, whereas including a hindered amine light stabilizer (HALS) hardly affected either the cure conversion or the cure rate due to its very low absorption of 365 nm. This result was confirmed by FTIR-ATR spectroscopy and UV-visible spectroscopy analyses. QUV ageing experiments showed that the cure conversion and durability were the highest for the UVA/HALS formulation at a ratio of 1 : 2, which is due to their synergistic action.