열방성 액정폴리에스테르와 폴리 ( 에틸렌 테레프탈레이트 ) 와의 블렌드

조정대(Jung Dae Cho),장용준(Yong Jun Jang),김윤준(Yoon Joon Kim),방문수(Moon Soo Bang),최재곤(Jae Kon Choi),조병욱(Byung Wook Cho) 한국공업화학회 2000 공업화학 Vol.11 No.6

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투명 전도성 ZITO/Ag/ZITO 다층막 필름 적용을 위한 아크릴레이트 기반 고분자분산액정의 전기광학적 특성 최적화

조정대 ( Jung-dae Cho ),김양배 ( Yang-bae Kim ),허기석 ( Gi-seok Heo ),김은미 ( Eun-mi Kim ),홍진후 ( Jin-who Hong ) 한국공업화학회 2020 공업화학 Vol.31 No.3

본 연구에서는 RF/DC 마그네트론 증착법을 이용하여 실온에서 유리 기판 상에 ZITO/Ag/ZITO 다층막 투명전극을 제조하였다. ZITO/Ag/ZITO (100/8/42 nm)로 이루어진 다층막 구조에 대해, 면저항이 9.4 Ω/m²이고 550 nm에서 투과도가 83.2%인 투명 전도성 필름이 얻어졌다. ZITO/Ag/ZITO 다층막 필름의 면저항 및 투과도 특성은 적외선(열선)을 효과적으로 차단할 수 있기 때문에 고분자분산액정(polymer-dispersed liquid crystal, PDLC) 기반 스마트 윈도우 적용에 매우 유용함을 알 수 있었으며 이로 인해 에너지 절약형 스마트 유리로서의 응용도 가능할 것으로 판단된다. 제조된 ZITO/ Ag/ZITO 다층막 투명전극을 적용한 2관능성 우레탄 아크릴레이트 기반 PDLC 시스템에 있어서 PDLC 층 두께 및 자 외선(ultraviolet, UV) 세기 변화가 전기광학적 특성, 광중합 동력학 및 표면 형태학에 미치는 영향을 조사하였다. 15 μm의 PDLC 층 두께를 가지며 2.0 mW/cm²의 UV 세기로 광경화된 PDLC 셀이 우수한 off-state 불투명도, 높은 on-state 투과 도 및 양호한 구동 전압을 나타냈다. 또한, 본 연구에서 제조된 최적 조건의 PDLC 기반 스마트 윈도우는 광을 효율적으로 산란시킬 수 있는 2~5 μm 크기의 양호한 마이크로 구조를 갖는 액정 droplet들이 형성되었으며, 이로 인해 우수한 최종 물성을 갖는 PDLC 셀이 제조되었다. ZITO/Ag/ZITO multilayer transparent electrodes at room temperature on glass substrates were prepared using RF/DC magnetron sputtering. Transparent conductive films with a sheet resistance of 9.4 Ω/m² and a transmittance of 83.2% at 550 nm were obtained for the multilayer structure comprising ZITO/Ag/ZITO (100/8/42 nm). The sheet resistance and transmittance of ZITO/Ag/ZITO multilayer films meant that they would be highly applicable for use in polymer-dispersed liquid crystal (PDLC)-based smart windows due to the ability to effectively block infrared rays (heat rays) and thereby act as an energy-saving smart glass. Effects of the thickness of the PDLC layer and the intensity of ultraviolet light (UV) on electro-optical properties, photopolymerization kinetics, and morphologies of difunctional urethane acrylate-based PDLC systems were investigated using new transparent conducting electrodes. A PDLC cell photo-cured using UV at an intensity of 2.0 mW/cm² with a 15 μm-thick PDLC layer showed outstanding off-state opacity, good on-state transmittance, and favorable driving voltage. Also, the PDLC-based smart window optimized in this study formed liquid crystal droplets with a favorable microstructure, having an average size range of 2~5 μm for scattering light efficiently, which could contribute to its superior final performance.

전자선 및 자외선 경화형 방무코팅용 모노머의 합성 및 물성비교

조정대 ( Jung Dae Cho ),이재성 ( Jae Sung Lee ),김양배 ( Yang Bae Kim ),홍진후 ( Jin Who Hong ) 한국공업화학회 2005 공업화학 Vol.16 No.3

TIZO/Ag/TIZO 다층막 투명전극을 이용한 폴리에스터 아크릴레이트 기반 고분자분산액정의 전기광학적 특성 연구

조정대 ( Jung-dae Cho ),허기석 ( Gi-seok Heo ),홍진후 ( Jin-who Hong ) 한국공업화학회 2022 공업화학 Vol.33 No.1

본 연구에서는 RF/DC 마그네트론 증착법을 이용하여 유리 기판 상에 실온에서 TIZO/Ag/TIZO 다층막 투명전극 필름을 증착하였다. 전체 박막 두께 60 nm TIZO/Ag/TIZO (10 nm/10 nm/40 nm)로 이루어진 다층막의 경우 650 nm에서 투과도는 86.5%, 면저항 값은 8.1 Ω/□를 나타냈으며, 적외선(열선)을 효과적으로 차단할 수 있는 투과도 특성 때문에 향후 에너지 절약형 스마트 윈도우로서의 적용도 가능할 것으로 판단된다. TIZO/Ag/TIZO 다층막 투명전극을 적용한 폴리에스터 아크릴레이트 기반 고분자분산액정(polymer-dispersed liquid crystal, PDLC) 시스템에 있어서 액정과 prepolymer의 함량비, PDLC 코팅층의 두께 및 자외선 세기 변화에 따른 전기광학 특성 및 표면 형태학에 미치는 영향이 조사되었다. 15 μm의 PDLC 층 두께에 1.5 mW/cm2의 UV 세기로 광경화된 TIZO/Ag/TIZO 다층막 투명전극 적용 PDLC 셀이 전반적으로 양호한 구동 전압과 on-state 투과도 및 뛰어난 off haze를 나타냈으며, PDLC 복합체의 고분자 매트릭스 표면에 형성된 액정 droplet들은 입사광을 효율적으로 산란시킬 수 있는 1~3 μm 크기를 갖고 있었다. 또한, 본 연구에서 제조된 TIZO/Ag/TIZO 다층막 투명전극 적용 PDLC 기반 스마트 윈도우는 연한 갈색의 색조를 띠고 있어서 심미적 측면에서 색다른 장점을 부여할 것으로 기대된다. Ti-In-Zn-O (TIZO)/Ag/TIZO multilayer transparent electrodes were prepared on glass substrates at room temperature using RF/DC magnetron sputtering. Obtained multilayer structure comprising TIZO/Ag/TIZO (10 nm/10 nm/40 nm) with the total thickness of 60 nm showed a transmittance of 86.5% at 650 nm and a sheet resistance of 8.1 Ω/□. The multilayer films were expected to be applicable for use in energy-saving smart window based on polymer-dispersed liquid crystal (PDLC) because of their transmittance properties to effectively block infrared rays (heat rays). We investigated the effects of the content ratio of prepolymer, the thickness of the PDLC coating layer, and the ultraviolet (UV) light intensity on electro-optical properties, and the surface morphology of polyester acrylate-based PDLC systems using new TIZO/Ag/TIZO transparent conducting electrodes. A PDLC cell with a thickness of 15 μm PDLC layer photocured at an UV intensity of 1.5 mW/cm2 exhibited good driving voltage, favorable on-state transmittance, and excellent off-haze. The LC droplets formed on the surface of the polymer matrix of the PDLC composite had a size range of 1 to 3 μm capable of efficiently scattering incident light. Also, the PDLC-based smart window manufactured using TIZO/Ag/TIZO multi-layered transparent electrodes in this study exhibited a light brown, which will have an advantage in terms of aesthetics.

산업용 SFF System에서의 Polyamide-6 파우더 소결 공정 개발

배성우(Sung-Woo Bae),김동수(Dong-Soo Kim),김형일(Hyung-Il kim),김충환(Chung-Hwan Kim),조정대(Jung-Dae Cho),최병오(Byung-Oh Choi) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

In this study, some kinds of polyamide-6 powders with different shape and particle size were fabricated to investigate the formability, the microstructure and mechanical properties. Also, to develop a more elaborate and rapid system, this study employs a new SLS device with a 3-axis dynamic focusing scanner system instead of the existing fθ lens used in commercial SLS. Polyamide-6 powders having the average size of 100 ㎛ were treated thermally in order to keep the spherical symmetry in shape. These polyamide-6 powders were mixed with polyamide-12 powders having the average size of 50㎛ to give the bimodal distribution of size. These mixed powders showed the better fabrication in the selective laser sintering process because the smaller particles of polyamide-11 played an important role in the compact packing of powders by filling the void space between the large particles of polyamide-6. Also, Experiments have performed to evaluate the effect of a scanning path and sintering parameter.

SLS 공정에서의 Polyamide-6 파우더 소결과 그 영향에 관한 연구

배성우(Sung-Woo Bae),김동수(Dong-Soo Kim),김형일(Hyung-Il Kim),김충환(Chung-Hwan Kim),조정대(Jung-Dae Cho),최병오(Byung-Oh Choi) 한국기계가공학회 2006 한국기계가공학회 춘추계학술대회 논문집 Vol.2006 No.-

In the solid freeform fabrication (SFF) system using selective laser sintering (SLS), polyamide-12 powder is currently recognized as general material. In this study, some kinds of polyamide-6 powders with different shape and particlesize were fabricated to investigate the formability, the microstructure and mechanical properties. Also, to develop a more elaborate and rapid system, this study employs a new SLS device with a 3-axis dynamic focusing scanner system instead of the existing f θ lens used in commercial SLS. Polyamide-6 powders having the average size of 100 m were treated thermally in order to keep the spherical symmetry in shape. These polyamide-6 powders were mixed with polyamide-12 powders having the average size of 50 m to give the bimodal distribution of size. These mixed powders showed the better fabrication in the selective laser sintering processbecause the smaller particles of polyamide-11 played an important role in the compact packing of powders by filling the void space between the large particles of polyamide-6. Also, Experiments have performed to evaluate the effect of a scanning path and sintering parameters by fabricating the various 3D objects.

새로운 열방성 액정중합체의 합성과 PET와의 블렌드

조정대,김희종,최재곤,조병욱,유지강 조선대학교 생산기술연구소 1997 生産技術硏究 Vol.19 No.1

Blends of new thermotropic liquid crystalline polymer(TLCP) with poly(ethylene terephthalate)(PET) were prepared by the coprecipitation from a common solvent. The thermal, mechanical properties and morphology of the blends(2wt%, 5wt%, lOwt% and 20wt% TLCP/PET) were examined. In the blends, liquid crystalline phase did not reveal any significant macrophase separation and thermal degradation at the processing temperature. According to the scanning electron micrograps, the TLCP domains in matrix were found to be more or less finely dispersed with 0.2㎛ to 0.4㎛ in size and interfacial adhesion between the TLCP and matrix polymer was excellent. Results of mechanical property measurement show that modulus of TLCP/PET blend was enhanced with increasing TLCP content.