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내크리프성이 향상된 동축 섬유형 변형률 센서의 계측 특성에 관한 연구
온승윤(Seung Yoon On),김성수(Seong Su Kim) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
In this work, a core-shell structured fiber sensor that has high creep resistance and high sensing performance for measuring mechanical strain is prepared by using a dry-jet wet spinning system and simple dip-coating method. The core part of the fiber sensor is made of ultra-high molecular weight polyethylene which has high modulus and strength. Additionally, microwave post-treatment process was introduced for enhancement of creep resistance of fiber sensor. The shell parts of the fiber sensor, electrically conductive layer, were formed by means of dip coating method. To enhance the sensing performance, the sandwich structured MWCNT conductive coating layer was introduced. Single filament tensile tests and creep test are performed to measure the mechanical properties and creep resistance of the fiber sensors, respectively. Finally, sensing performance of sensor fiber was evaluated.
터보 컴프레셔용 복합재료 틸팅 패드 저널 베어링의 특성에 관한 연구
온승윤(Seung Yoon On),유준일(Jun Il You),김성수(Seong Su Kim) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
A tilting pad journal bearing is employed to turbine, compressor, pump and generator applications because of its high load carrying capacity, excellent stability and service durability at high operation speed than conventional metal journal bearings. For the high performance under sever operating condition, a tilting pad journal bearing should reduce vibration of the overall bearing systems. Therefore, the bearings are designed to have excellent dynamic characteristic. In this work, a hybrid composite tilting pad journal bearing was fabricated using carbon-fiber/epoxy composite to increase the dynamic properties. The modal analysis was performed to investigate dynamic stability of composite tilting pad. The stiffness and damping coefficient of fluid film at hydrodynamic lubrication state were calculated by finite difference method (FDM). To verify the analysis results, the hydrodynamic lubrication tess of the composite and white metal tilting pad journal bearings were conducted using an industrial test bench. As a result, the composite tilting pad journal bearing effectively reduced vibration and increased stability and durability of the bearing systems that the white metal tilting pad journal bearing.
초박형 반도체 패키지의 EMC encapsulation을 위한 경화 공정 개발
박성연 ( Seong Yeon Park ),온승윤 ( Seung Yoon On ),김성수 ( Seong Su Kim ) 한국복합재료학회 2021 Composites research Vol.34 No.1
본 연구에서는 면상 발열체인 CNT Heater를 이용한 EMC 패키지 경화 공정 시스템을 개발하기 위하여, 기존 Hot Press 공정과 CNT Heater 공정 시스템을 통해 제작한 EMC/Cu Bi-layer 패키지의 성능을 비교하여 CNT Heater 공정 시스템의 가능성을 확인하였다. CNT Heater 공정의 경화 사이클을 도출하기 위해 Rheometer를 이용해 EMC의 점성을 측정하였다. 앞서 언급한 두 공정에 의해 성형된 EMC/Cu Bi-layer 패키지에서 EMC 내부의 Void를 광학 현미경으로 분석하였다. 또한, C-Scanning Acoustic Microscope와 3D-Digital Image Correlation를 통해 EMC/Cu Bilayer 패키지의 계면 Void와 휨을 분석하였다. 이러한 분석 결과를 기반으로, EMC 내부 및 EMC/Cu Bi-layer의 계면에서 Void가 없음을 확인하였으며, 상온에서의 휨 크기, Zero 휨 온도와 휨 크기 변화에서 차이가 없음을 확인하였다. In this paper, the Curing process for Epoxy Molding Compound (EMC) Package was developed by comparing the performance of the EMC/Cu Bi-layer package manufactured by the conventional Hot Press process system and Carbon Nanotubes (CNT) Heater process system of the surface heating system. The viscosity of EMC was measured by using a rheometer for the curing cycle of the CNT Heater. In the EMC/Cu Bi-layer Package manufactured through the two process methods by mentioned above, the voids inside the EMC was analyzed using an optical microscope. In addition, the interfacial void and warpage of the EMC/Cu Bi-layer Package were analyzed through C-Scanning Acoustic Microscope and 3D-Digital Image Correlation. According to these experimental results, it was confirmed that there was neither void in the EMC interior nor difference in the warpage at room temperature, the zero-warpage temperature and the change in warpage.