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환경조건에서 유체 동점성에 따른 하이드로 부시 특성변화에 관한 연구
손현철(Hyunchul Sohn),이홍기(Hongki Lee),박성욱(SungUk Park) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5
Anti-vibration rubbers are applied to vehicle suspension and sub-frame systems. Generally, conventional type rubber has good isolation performance at high frequency range due to low dynamic stiffness, but it has bad isolation performance at low frequency due to low damping coefficient. Therefore, many hydraulic bushes are used in vehicle to reduce vibration and noise caused by structure resonance. Hydraulic bush consists of main rubber part and fluid part. Main rubber part plays an elastic role (stiffness), and fluid part plays a viscose role (damping). Damping of fluid generates by flow through inertia track, and influences by fluid’s dynamic viscosity. Fluid is compounded to meet maximum freezing point and minimum boiling point. In this paper, we study dynamic characteristics of hydraulic bush according to various viscosity of fluid. Also, we study change trends of fluid viscosity under various environment condition (temperature). Finally, we measure dynamic characteristic under various temperature conditions. The results of experiments show that dynamic characteristics of hydraulic bush influenced by fluid dynamic viscosity
손현철(Hyunchul Sohn),박승욱(Seunguk Park),박성욱(SungUk Park) 한국자동차공학회 2016 한국자동차공학회 부문종합 학술대회 Vol.2016 No.5
Anti-vibration rubbers are applied to vehicle suspension systems. Generally, conventional type rubber has good isolation performance at high frequency range due to low dynamic stiffness. But, it isn’t suitable for use at resonance occurrence because of low damping coefficient. Therefore, many hydraulic bushes are used in vehicle to reduce vibration and noise caused by structure resonance. Hydraulic bush consists of main rubber part and fluid part. Main rubber part plays an elastic role (stiffness), and fluid part plays a viscose role (damping).Hydraulic bushes are classified by inertia track type. Kinematic type has inertia track with long length and wide area, and has low volume stiffness. Friction type has inertia track with short length and narrow area, and has high volume stiffness. Hybrid type has middle property between kinematic type and friction type. In this paper, we experiment vehicle brake judder test by using these hydraulic bush types. To make brake judder, we make specially brake disc by machining. We are measured displacements and accelerations at radial and axial directions of hydraulic bushes under braking 0.7G, 0.5G, and 0.2G conditions. Finally, we can find hydraulic parameters with high sensitivity of brake judder performance.
배전급 초전도 케이블의 상전도계통 적용시 보호협조 특성연구
이현철(HyunChul Lee),류경우(KyungWoo Ryu),황시돌(SiDole Hwang),손송호(SongHo Sohn),임지현(JiHyun Lim),이근준(GeunJoon Lee) 대한전기학회 2008 대한전기학회 학술대회 논문집 Vol.2008 No.11
In this paper, the protective coordination studied in application of HTS cable in conductive system. The protective coordination analyzed to HTS cable using the PSCAD/EMTDC. HTS cable simulated to be appling SFCL or not to be. The result was showed to be protective coordination graph in HTS cable and OCR curve at the power system fault. This graph was proposed to be power operation standard at the HTS cable fault.
Characteristics of junctionless charge trap flash memory for 3D stacked NAND flash.
Oh, Jinho,Na, Heedo,Park, Sunghoon,Sohn, Hyunchul American Scientific Publishers 2013 Journal of Nanoscience and Nanotechnology Vol.13 No.9
<P>The electrical characteristics of tunnel barrier engineered-charge trap flash (TBE-CTF) memory devices with junctionless (JL) source and drain (S/D) were investigated. The JL structure is composed of an n(+)-poly-Si based ultra-thin channel and S/D with identical doping concentrations. The band engineered Hf-silicate/Al2O3 tunnel barrier stack was applied to a JL-TBE-CTF memory device in order to enhance the field sensitivity. The Hf-silicate/Al2O3 tunnel barrier, HfO2 trap layer, and Al2O3 blocking layer were deposited by atomic layer deposition. The fabricated device exhibited a large memory window of 9.43 V, as well as high programming and erasing speeds. Moreover, it also showed adequate retention times and endurance properties. Hence, the JL-TBE-CTF memory (which has a low process complexity) is expected to be an appropriate structure for 3D stacked ultra-high density memory applications.</P>