Real-Time IR을 이용한 Polyesterimide의 경화거동 연구

홍진후,송주명,김현경,박미영,박기주 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.2

Polyesterimide for enamel Wire coating was synthesized and its curing reaction was monitored by real-time FT-IR. Infrared 1019cm^(-1) band was used to monitor the curing process. Results of in-situ analysis showed that evaporation of ethylene glycol and transesterification started from 100℃. When curing temperature was higher than 200℃, ester reaction was favored over the ether reaction. It was concluded that curing temperature is the key factor to control the thermal stability of the enamel wire coating.

자외선 경화형 아크릴 모노머를 통한 옻칠 개질 및 코팅 물성 연구

홍진후,박미영,김현경,박기주 조선대학교 생산기술연구소 1998 生産技術硏究 Vol.20 No.2

UV-Curable acryl monomer containing quaternary ammonium salt has been synthesised and Introduced into the orintal lacquer by dual curing method. Electrical and thermal mechanical properties were studied in view of the interpenetrating polymer network theory. Although modification of oriental lacquer could not introduce antistatic properties into coating network, tremendous improvement in the properties of breaking voltage was observed.

하이브리드 광경화를 이용한 소광 도료 연구

홍진후,주형태,한승택 조선대학교 생산기술연구소 2004 生産技術硏究 Vol.26 No.1

We investigated the effects of photosynergist and LED curing on the kinetic and film properties of UV curable coatings containing micro-silica. Cure kinetics were studied by DPC and the degree of curing at the surfaces and the interfaces with substrate were investigated by FT-IR/ ATR. Coating properties such as hardness, gloss, chemical and stain resistances and adhesion of the UV cured films containing various concentration of micro-silica were investigated. The results showed that UV cured films containing micro-silica provide an excellent matting property while sacrificing chemical resistance due to the surface morphology and oxygen inhibition. The UV cured films containing photosynergist produced superior surface properties such as chemical resistance while sacrificing the adhesion and matting properties. LED-UV dual curing system was proposed to optimize the process for the system where both high matting and excellent coating properties are required.

에폭시/TETA계의 경화 및 물성 연구

홍진후,박미영,김현경 조선대학교 생산기술연구소 1999 生産技術硏究 Vol.21 No.2

The curing of diglycidyl ether of bisphenol A (DGEBA) with triethyl-enetetramine (TETA) under controlled thermal conditions was discussed. A real-time FT-IR ATR was employed to determine crosslinking reactions and degree of cure. Infrared 914cm^(-1) band was used to monitor the conversion of the reactions. To measure the thermal mechanical properties of the various systems, DMTA was employed. Results of ATR and DMTA data show that optimum TETA/DGEBA ratio was about 0.1. When the ratio was higer than 0.1. a phase separation was occurred with short pot life. It is demonstrated that real-time FT-IR ATR is powerful technique to better understand the formulation-process-property relationship of the Epoxy ITETA system.

실리카 입자를 함유한 광경화형 도료 물성

홍진후,주형태,김순기,김석찬 조선대학교 생산기술연구소 2004 生産技術硏究 Vol.26 No.1

We investigated the effects of nano-silica on the kinetic and film properties of UV curable coatings. Coating properties such as hardness, gloss, chemical and stain resistances and adhesion of the UV cured films containing various concentration of nano-silica were investigated. The matting, pencil hardness, chemical resistance, and abrasion resistances were apparently improved Via addition of nano-silica. Pendulum hardness was also enhanced with the increasing content of nano-silica up to 5 weight percent. However, the pendulum hardness and the adhesion decreased as nano-silica content increased above 10 weight percent. DPC analysis revealed that the presence of nano-silica in UV curable coating formulation enhanced photo curing. It was demonstrated that hardness. abrasion resistance, and chemical resistance of UV cured film can be increased without loss of optical properties through nanocomposite.

폴리올레핀 자동차 범퍼수지의 화학적 재활용 연구

지성완,홍진후,최재곤 조선대학교 생산기술연구소 1998 生産技術硏究 Vol.20 No.2

Recycling of thermoplastic polyolefins bumper has been carried out by stirring a coarse-crushed plastic material inside a chemical reactor using dichloromethane(MC) to release the paint film and drying the solvent. Chemical method adversely affects the physical properties or surface quality of the final product. It was found that wettability and surface tension of these polymers did not influence coating properties significantly. The diffusion coefficient of MC in PP/EPR blend has been monitored using an attenuated total reflection FT-IR. The test also demonstrated both the accuracy and quickness of FT-IR ATR experiment for measuring the diffusion coefficient of chemical recycling system Crystallinity and fractional free volume were very sensitive to the diffusion rates of small molecules in polymers as well as to the composition in recycled PP/EPR blends. It was suggested that concentration of the PP/EPR resins obtained from recycling process must be lower than 40wt percent in compounding.

Dielectric Analysis(DEA)를 이용한 옻칠의 분자완화 및 경화과정에 관한 연구

김현경,유지강,홍진후 조선대학교 생산기술연구소 1998 生産技術硏究 Vol.20 No.2

Curing behavior of oriental lacquer has been characterized using the dielectric analysis(DEA). It was found that the oriental lacquer cured to its hardened state most efficiently at moderate temperature in the presence of air at relative humidities of greater than 70%. In order to study the dielectric properties of oriental lacquer film, various films have been prepared differing curing procedures. The glass transition and secondary relaxation temperatures of ordinary oriental lacquer film were observed at 45℃ and -40℃, respectively. On the contrary, the high temperature cured film showed a secondary relaxation at around -50℃. The relationship between thermodynamic properties and chemical structures has been discussed based or, the analysis of the dielectric relaxation behavior using the Cole-Cole plot and the dielectric relaxation intensity

ESPI 기법에 의한 하중을 받는 균열 박판의 진동 특성에 관한 연구

김경석,강기수,최지은,박찬주,홍진후 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.2

대부분의 실제구조물은 인장과 진동 등이 동시에 작용하는 복합하중 상태가 되며 이러한 환경에서 물체의 거동을 해석하는 것이 중요하다. 이 논문에서는 χ축에 대해 45˚결함이 있는 평판이 하중을 받고 있을 때, 진동 특성을 시간평균 electro speckle pattern interferometry(ESPI)를 이용하여 해석하였다. 결함이 있는 박판 시험편에 인장력을 증가하면서 물체의 고유진동수 변화와 모드의 형태 변화를 동시에 관찰하였다. 실험결과에서 결함은 저차모드에서는 진동모드에 영향을 주지 않았으나, 고차모드에서는 진동모드에 변화를 주었으며, 특정 진동모드에서 결함의 영향으로 현저하게 고유주파수가 낮아지는 경향을 보였다. 또한 실험결과는 유한요소해석과 비교하여 주파수 비교에서는 5%이내의 오차율을 보였으며, 진동모드 비교에서는 완전히 일치하였다. This paper presents the vibration characteristics of a rectangular plate with 45˚ oblique crack subjected to a uniaxial tension. The experiment is adopted by the time-average Electronic Speckle Pattern Interferometry(ESPI) method. The natural frequency and mode shape are considered accurately according to the increase of tensile load. When tensile load is zero, the vibration modes are agreed with the smooth and the 45˚ obliquely cracked plate. But according to the increasement of load, it is shown that vibration modes are extremely varied. The effects of the crack under the vibration are discussed in detail. It is indicated that the increase of load makes the variation of the frequencies and modes complicate in the range of even a small load. The results are agreed with the FEM analysis within 5%.

Senescence-Associated MCP-1 Secretion Is Dependent on a Decline in BMI1 in Human Mesenchymal Stromal Cells

Jin, Hye Jin,Lee, Hyang Ju,Heo, Jinbeom,Lim, Jisun,Kim, Miyeon,Kim, Min Kyung,Nam, Hae Yun,Hong, Gyong Hwa,Cho, You Sook,Choi, Soo Jin,Kim, In-Gyu,Shin, Dong-Myung,Kim, Seong Who Mary Ann Liebert 2016 Antioxidants & redox signaling Vol.24 No.9

Surface and Dielectric Properties of Oriental Lacquer Films Modified by UV-Curable Silicone Acrylate

Hong, Jin-Who,Kim, Hyun-Kyoung The Polymer Society of Korea 2006 Macromolecular Research Vol.14 No.6

In order to achieve an oriental lacquer (OL) film with a thick consistency, UV-curable silicone acrylate (SA) was added to OL by a dual curing process. The addition of 5 wt% UV-curable SA to the OL fomulation enabled the preparation via a single drying step of a $77{\mu}m-thick$ film exhibiting excellent surface properties. FTIR-ATR was used to investigate the effect of UV-curable SA on the behavior of film formation during curing, and the relaxation behavior of the produced films was investigated by dielectric spectroscopy. Dielectric properties were measured in the frequency range $10^{-2}-10^5\;Hz$ at various temperatures between -100 and $200^{\circ}C$. The results demonstrated that OL modified by UV-curable SA has a higher glass transition temperature and stronger secondary relaxation at a lower temperature than the conventional OL system. The OL film modified with UV-curable SA was presumed to be harder at the surface and tougher than conventional OL film.