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볼 베어링과 스퀴즈 필름 댐퍼로 지지되는 차량용 터보차저의 회전체동역학 해석: 스퀴즈 필름 댐퍼 설계 인자와 회전체 불균형 질량의 영향
김규만,류근 한국트라이볼로지학회 2018 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.34 No.1
Modern high-performance automotive turbochargers (TCs) implement ceramic hybrid angular contact ball bearings in series with squeeze film dampers (SFDs) to enhance transient responses, thereby reducing the overall emission levels. The current study predicts the rotordynamic responses of the commercial automotive TCs (compressor wheel diameter = ~53 mm, turbine wheel diameter = ~43 mm, and shaft diameter at the bearing locations = ~7 mm) supported on ball bearings and SFDs for various design parameters of SFDs, including radial clearance, axial length, lubricant viscosity, and rotor imbalance conditions (i.e., amplitudes and phase angles) while increasing rotor speed up to 150 krpm. This study validates the predictive rotor finite element model against measurements of mass, polar and transverse moments of inertia, and free-free mode natural frequencies and mode shapes. A nonlinear rotordynamic model integrates nonlinear force coefficients of SFDs to calculate the transient responses of the TC rotor-bearing system. The predicted results show that SFD radial clearances, as well as phase angles of rotor imbalances, have the paramount effect on the dynamic responses of TC shaft motions.
김규만,최재철,오정훈,이용민,유명현 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
Silicon is a promising anode candidates owing to high theoretical capacity of 3500 mAh g<sup>-1</sup>, which is almost 10 times higher than the capacity of conventional graphite. However, they experience large volume expansion during cycling. Therefore, a critical capacity loss causes after a few cycles. To alleviate this expansion, the choice of binder for holding all of the materials in the Si anode is very important. In order to overcome the limitation commercial binder polyvinylidene fluoride (PVdF), many researchers have proposed new polymeric binder. Herein, we fabricate silicon anodes with highly adhesive and soluble co-polyimide (P84) binder. Their adhesion and electrochemical properties are evaluated by comparing commercial PVdF binder system.
A 3D Adhesion Map Based on SAICAS for Predicting Adhesion Properties of the Electrodes
김규만,변승우,조인성,이용민,유명현 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.1
When we prepare electrodes for lithium-ion batteries (LIBs), several electrode design parameters such as density, thickness, etc. are predetermined depending on the targeted energy density. In this regard, an optimum binder content always lefts a difficult problem, because there is no systematic study on adhesion properties for electrodes. Also, only the conventional peel test has widely used to compare electrode adhesion strength. Herein, our group has introduced a tool, the Surface and Interfacial Cutting and Analysis System (SAICAS), to measure adhesion strength of the LIBs electrodes. we applied the SAICAS tool to measure all the adhesion properties of LiCoO2 electrode having three different loading, 5, 10, and 15 mg cm<sup>-2</sup>, and four different densities, 2.0, 2.5, 3.0, and 3.5 g cm<sup>-3</sup>.
김규만,노용래,강길환 한국기계가공학회 2006 한국기계가공학회지 Vol.5 No.3
A new method to fabricate metal electrodes on side wall of the microchannel is presented. Electrical signal can be measured by the metal electrodes on channel side wall when microparticles pass through a polymer microchannel. 3 dimensional metal electrodes on channel side wall could be fabricated by local deposition of metal through a shadowmask and inclined evaporation. The polymer microchannel with side wall electrodes could be precisely aligned onto metal contact patterns on pyrex glass. The impedance measurement test showed possibility of electrical signal measurement using the fabricated device.