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신대영(D. Y. Shin),서동진(D. J. Seo),윤주섭(J. S. Yun),장주섭(J. S. Jang),오주영(J. Y. Oh),최병운(B. Y. Choi) 유공압건설기계학회 2014 유공압건설기계학회 학술대회논문집 Vol.2014 No.9
This study is on problem of jamming gears, which is one of the most degrading factors in hydraulic motor performance. The phenomenon of gear sticking to the inside of a hydraulic motor housing was mathematically modeled as quantitative value of wear, and then structural analysis according to the geometric shape of the motor was performed as an analysis. Also in order to improve the manufacturing quality, a method was proposed to lower the defect rate by statistically analyzing the manufacturing process for parts exposed to wear. The analysis showed that 62.6% of parts hydraulic motor were exposed to wear. For the future, optimization of dimensions, addition of clearance values, and improvement of manufacturing process should be further studies in order to minimize wear and increase the mechanical efficiency.
정규홍(G. H. Jung),신대영(D. Y. Shin),서동진(D. J. Seo) 유공압건설기계학회 2015 유공압건설기계학회 학술대회논문집 Vol.2015 No.10
As heavy-duty construction vehicles such as excavators are required for good engine-room cooling capacity, cooling fan drive mechanism adopts a hydraulic gear motor, which can actively control the output speed, instead of conventional ON/OFF type belt drive. While gear motors are normally limited to 140bar of operating pressure, those for cooling fan are capable of operating at continuous pressures of up to 220bar. After assembly, all the high pressure gear motors must pass through aging test which is a wearing process between the gear teeth and motor housing for gradual pressure increment and gear sticking incurred by abnormal wear results in defectives. This paper deals with the gear-sticking free aging test controller that is designed together with the knowledge of experienced operator and the analysis results of experimental data for gear jamming phenomenon. From the aging experiment, the developed controller that can alter the setting pressure of load pump proves to be effective for stabilizing the abrupt increase in motor input pressure and thus prevents the hydraulic motor from stopping. This is expected to be helpful for the decline of defective and productivity movement.
나기대,모양우,유영태,서동진 조선대학교 생산기술연구소 1997 生産技術硏究 Vol.19 No.1
Functional operator is derived for the propagation factor and characteristic impedance in hydraulic pipe lines when the effects of varying velocity profile and heat transfer are included. The results of theoretical analysis are compared with experimental results obtained from response characteristics. These results are particularly used to determine the impulse and step responses of a line. The impulse and step responses of an infinitely long uniform rigid line are computed in a viscous liquid. The waveform is measured due to propagation factor by means of oscilloscope whenever ball valve constructed in a pipe downstream was closed and opened repeatedly.
박지용,모양우,서동진,정지철,유영태 朝鮮大學校 機械技術硏究所 1998 機械技術硏究 Vol.1 No.1
To date many approaches to the pipe line have been suggested on the basis of no viscosity and without consideration of pressure loss due to the friction of fluid inside pipe line. Also, many researches have been performed assuming that the slope of velocity by viscosity is in direction of flow, while velocity is constant in the cross section pipe line. The present work purports to study both experimentally and analytically the transient response characteristics of unsteady laminar flow of a pipe line. The transfer function for the pressure wave is derived for the case of a pipe line having relatively small diameter. The effect of viscosity is included at the derivation. The transient response characteristics predicted by the analytical result are compared with the experimental results. The pulsating flow is generated by the ball valve and speed controler equipped D.C. motor, the characteristics of the pulsating laminar flow in a pipe are measured by the pressure transducer and the oscilloscope. The experimental results indicate that the analytical derivation is adequate the experimental data compare favorably with the analysis.