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안병현 ( Byung Hyun Ahn ),임상혁 ( Sang Hyuk Im ) 한국화상학회 2021 한국화상학회지 Vol.27 No.1
가교된 단분산 폴리스티렌 비드를 유화 중합과 분산 중합으로 합성하였다. 가교된 폴리스티렌 비드를 자일렌과 iron pentacarbonyl로 팽윤시킨 후 옥틸 에테르와 함께 환류하여 iron pentacarbonyl을 산화철로 변환시켰다. 산화철의 화학 안정성을 향상시키기 위해 산화철을 포함하는 폴리스티렌 비드를 실리카로 코팅하였다. 소결로 폴리스티렌 비드를 제거하여 산화철을 포함하는 중공 실리카 비드를 얻었다. 전체 합성 과정에서 모든 비드의 크기와 형태는 균일하게 유지되었고, 산화철을 포함하는 중공 실리카 입자는 강한 자성을 보였다. Cross-linked and monodispersed polystyrene beads were synthesized via both emulsion and dispersion polymerization. After the cross-linked polystyrene beads were swollen by xylene and iron pentacarbonyl, they were heated with octyl ether at reflux to transform iron pentacarbonyl to iron oxide. The cross-linked polystyrene beads containing iron oxides were coated by silica to improve chemical stability of the iron oxides. Hollow silica beads containing iron oxides were obtained after the cross-linked polystyrene were removed by sintering. All beads maintained their uniformity in size and shape through the entire synthesis and the hollow silica beads containing with iron oxide showed strong magnetism.
회전익 항공기 기어박스 상태감시진단을 위한 음향신호 잡음제거 방법에 관한 연구
안병현(Byung Hyun Ahn),김효중(HyoJung Kim),박선휘(Sunwhi Park),김용석(YongSeok Kim),최병근(ByeongKeun Choi) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4
Gearboxes are very important for many industrial applications such as wind turbine, power generators and rotorcraft gearboxes. Most of all, this research is focused on rotorcraft gearboxes and condition monitoring & diagnosis system. the purpose of health and usage monitoring(HUM) is to improve flight safety, rotorcraft availability, maintainability, the ability to complete a transmission, and to reduce life cycle costs. Acoustic Emission technique is widely applied to develop the early fault detection system for predictive maintenance, and the problem is about a signal processing method for AE signal mainly focused on. but AE frequency is usually in the range of 150-300 kHz which means it has huge modulated data in signal. it has a advantage of early fault detection but also predictive maintenance while a variety of irrelevant data reduces the performance of condition indicators. that is typically noise from the rotorcraft transmissions and bearings. In this paper, Advanced research is performed by noise reduction techniques in time domain and frequency domain by using AE signal from the motor gearbox. In order to study on rotorcraft gearboxes for condition monitoring and diagnosis.
분산중합에 의한 폴리스티렌-폴리에테르이미드 코어-셀 입자의 합성
안병현 ( Byung Hyun Ahn ) 한국공업화학회 2014 공업화학 Vol.25 No.5
Polystyrene-poly(etheramic acid) core-shell particles were prepared by dispersion polymerization of styrene using poly(etheramicacid) obtained by the reaction of 2,2`-bis[4-(3,4-dicarboxyphenoxy) phenyl]propane dianhydride and 3,5-diamniobenzoicacid as a stabilizer. 4-Vinylbenzyltrimethylammonium chloride was used as a comonomer to increase the binding efficiency of poly(etheramic acid). When the ethanol-water mixture (7 : 3) was used as a reaction medium, particles were stabilized well and the size distribution of particles was fairly narrow. The particle size increased with the amount of styrene. The particles polymerized in the dimethylformamide-water mixture had a broad size range. Polystyrene-poly(etheramic acid) core-shell particles were transformed to polystyrene-polyetherimide core-shell particles by the chemical imidization of shells.