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김기상,김석일 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.4
One of the important considerations in designing a machine tool is the durability. In this study, a durability estimation system for horizontal machining centers is developed to evaluate the effects of structural specification and driving condi-tions on the durability. All loads such as weights, inertia forces, cutting force and so on, are automatically transferred from the upper elements to the lower elements by the force flows which can he derived from the structural code of horizontal machining centers. And the external loads applied to the motion elements such as beatings, LM guides, ball screws and so on, are determined by the equilibrium conditions of force and moment. Especially, the durability of horizontal machining centers is estimated based on the lifes of motion elements operating under the desired driving conditions.
아크릴계 공중합체에서 이소보닐 메타크릴레이트의 함량에 의한 물리적 특성 변화
김기상,심상연 한국유화학회 2016 한국응용과학기술학회지 Vol.33 No.4
내열, 코팅 및 접착특성이 우수한 아크릴계 공중합체를 설계, 제조하였다. 공중합체용 모노머 로 methyl methacrylate(MMA), isobornyl methacrylate(IBMA) 그리고 2-hydroxyethyl methacrylate (HEMA)를 사용하여 괴상 중합 및 유화 중합으로 반응하여 > 95%이상 고수율로 중합체를 제조하였다. 1H-NMR로 화학구조를 확인하였고 DSC, DMA, TGA분석으로 내열성을 확인한 결과 유리전이온도가 123 ℃이상 140 ℃까지 높게 나타났다. 또한, IBMA성분이 증가함에 따라 저장 탄성율, 열분해온도 모 두 증가하였다. 인장강도는 IBMA의 함량이 전체 모노머 조성물중 10%에서 30%로 증가함에 따라 괴상 및 유화 중합체 모두에서 22에서 30 MPa로 강도가 증가하였으며 IBMA의 소수성 특성으로 접촉각은 70도에서 88도까지 증가함을 확인하였다. The acrylate copolymer having good thermal stability, coating and adhesion properties was designed and prepared. We prepared copolymers in >95% high yield using methyl methacrylate, isobornyl methacrylate and 2-hydroxyethyl methacrylate monomers by the bulk and emulsion polymerization techniques. The 1H-NMR spectrum was used to identify chemical structure and glass transition temperatures increased from 123 ℃ to 140 ℃ confirmed by DSC, DMA and TGA analysis. In addition, as the content of IBMA increased, storage modulus and thermal decomposition temperature increased. As the content of IBMA increased from 10% to 30% in the composition for the entire monomer, tensile strength increased from 22 to 30 MPa in both polymers prepared by bulk and emulsion techniques. The contact angle increased from 70 to up to 88 degrees due to hydrophobic property of IBMA.
김기상,이명원,유천권,이연태,정태화,손건영,이복권 대한미생물학회 1987 大韓微生物學會誌 Vol.22 No.1
In order to determine the virulence properties of eleven strains of Sh, flexneri isolated from diarr- heal patients the congo red test, the Sereny test, the I-leLa cell invasion test and etectrophotesis of pl- asmids were carried out. The results were summarized as follows. 1. Virulent strains were not determined by the result of Congo red absorption test. 2. Virulent strains showed positive reaction by the Sereny test and the HeLa cells invasion, but aviru- lent strains revealed negative reaction at those tests. 3. The temperature condition of bacterial growth was a factor of viru lent expression. 4. Virulent strains were mostly possessed of a 130.3 Mdal plasmid, but avirulent strains were not.
불소함유 아크릴계공중합체에서 히드록시에틸메타크릴레이트 함량에 따른 물리적 특성 변화
김기상,심상연 한국응용과학기술학회 2018 한국응용과학기술학회지 Vol.35 No.2
The acrylate copolymer having good coating, water-repellent and adhesion properties was designed and prepared. We prepared copolymers with high yield of > 95% using methyl methacrylate(MMA), 2,2,2-trifluoroethyl acrylate (FMA) and 2-hydroxyethyl methacrylate monomers(HEMA) by either bulk or emulsion polymerization techniques. The 1 H-NMR spectrum was used to identify chemical structure and DSC and DMA analysis were conducted. As a result, the glass transition temperature decreased by 3 ℃ as FMA content increased from 5% to 10%, and decreased by 2 ~ 8 ℃ when HEMA content increased from 5 % to 10 %. The physical properties were measured using Instron and TGA. As FMA or HEMA content increased by 10%, tensile strength decreased from 29 MPa to 22 MPa and Td decreased from 200 ℃ to 180 ℃ in both bulk and emulsion. The contact angle relatively decreased as hydrophilic HEMA content increased. 코팅, 발수 및 접착특성이 우수한 불소함유 아크릴계 공중합체를 설계, 제조하였다. 공중합체용 모노머로 methyl methacrylate(MMA), 2,2,2-trifluoroethyl acrylate(FMA) 그리고 2-hydroxyethyl methacrylate(HEMA)를 사용하여 괴상 중합 및 유화 중합으로 반응하여 > 95 %이상 고수율로 공중합 체를 제조하였다. 1 H-NMR로 화학구조를 확인하였고 DSC와 DMA로 물성분석을 한 결과, FMA의 함량이 5 %에서 10 %로 증가함에 따라 유리전이온도는 3 ℃ 감소하였으며 HEMA의 경우에는 감소폭이 2 ~ 8 ℃로 나타났다. Instron 및 TGA를 이용한 분석에서는 FMA 혹은 HEMA 함량이 10 % 증가함에 따라 괴상 및 유화 중합체 모두에서 인장강도는 29 MPa에서 22 MPa로 감소하였고 Td는 200 ℃에서 180 ℃로 감소하는 경향을 나타내었다. 접촉각은 친수성인 HEMA의 함량이 증가함에 따라 상대적 으로 감소하였다.
Novel silicone containing hydrogels
김기상,심상연 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
Surface tailoring to achieve oxygen permeability and bio-compatibility properties in coating bycombining acrylic polymer with silicone is of great interest in the field of contact lens. Thus, we developed a novel silicone containg monomer. 2,3-bis((trimethylsliyl)oxy)propyl methacrylate (BSM), as a silicone containing monomer, was prepared in 91% yield by the condensation reaction of glycerol mono methacrylate with chlorotrimethylsilaneand then used as co-monomers for the hydrogels preparation. AIBN was used as a radical initiator. Hydrogels were prepared from various molar ratios of 2-hydroxyethylmethacrylate (HEMA), ethylene glycol dimethacrylate and silicone containing monomers at 110°C, 30 min polymerization. Hydrogels containing silicone show a little bit lower water contents and tensile strengthsthangeneral hydrogel. In a preliminary test, silicone containing monomer show lower reactivity in photo-polymerization maybe due to bulky side chain of BSM.