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김성윤(SㆍYㆍKim),김유택(YㆍTㆍKim),남청도(CㆍDㆍNam),이영호(YㆍHㆍLee),강호근(HㆍKㆍKang),김성동(SㆍDㆍKim) 한국마린엔지니어링학회 2005 한국마린엔지니어링학회 학술대회 논문집 Vol.2005 No.-
The effect of break down of centrifugal pump due to entrained air has not been clarified yet. Thus, air-water two-phase flow experimental apparatus was installed to clarify the effect of break down. The performance results of a single-phase flow satisfied reappearance. Also, the heads coincided well impeller types.
김성동(S. D. Kim),전세형(S. H. Jeon),진광호(K. H. Jin) 유공압건설기계학회 2014 유공압건설기계학회 학술대회논문집 Vol.2014 No.9
In the work, it was studied to use a pressure signal instead of the flow rate and spool displacement signals to diagnose the valve dynamic performance. The mathematic model of a servo valve was derived and the model parameters were accurately identified to represent the real servo valve. A series of computer simulation works were done to measure the bandwidth frequencies to represent the dynamic property of the servo valve in closed-ports condition. When outlet ports are set to be of tiny volume, the –90〫phase frequencies of the load pressure were found to be well coincide with those of spool displacement.
김성동(S. D. Kim),전세형(S. H. Jeon),주별진(B. J. Joo),윤소남(S. N. Yoon) 유공압건설기계학회 2013 유공압건설기계학회 학술대회논문집 Vol.2013 No.6
Common type of servovalves is to control flowrate measuring and diagnosis of servovalve`s hysteresis is based upon analysis of flowrate signal. The ISO 10770-1 and KS B 6511 regulations for servovalve`s hysteresis are also established from analysis of flowrate signal. The measurement of flow is hard to implement. In this study, some hysteresis diagnosis methods are investigated to use pressure signal and spool displacement signal. Three kinds of hysteresis; flowrate hysteresis, pressure hysteresis and spool displacement hysteresis are measured from an experiment set-up. Two kinds of pressure hysteresis; pressure gain hysteresis and no-load pressure hysteresis are investigated. The spool displacement hysteresis is found to be the most accurate and pressure hysteresis are also good enough as well as flow hysteresis. The pressure gain hysteresis shows a little error from other hysteresis, and it is estimated because geometric dimension error of spool and sleeve affects the hysteresis.
Conceptual Design on a Direct-Operated Relief Valve with High-Precision and Large-Flow
S. D. Kim(김성동),J. H. Kim(김준현) 유공압건설기계학회 2021 유공압건설기계학회 학술대회논문집 Vol.2021 No.11
Conventional direct-acting relief valves have a few critical disadvantages. The three known disadvantages are the low pressure precision, the low allowable flow rate, and unstable chattering phenomena. In this research, design concepts are presented to improve the above mentioned disadvantages. Four key design concepts are applied in a direct-operated relief valve to achieve high pressure precision, large flow, and less chatter. The design concepts consist of poppet-opening flow-force configuration to balance the pressure force with spring force, a variable-elasticity spring to match the spring elasticity to the flow-force elasticity, a stabilization damper to achieve anti-chattering property, and a pilot piston that has small pressurizing area. The poppet-opening flow-force and the variable-elasticity spring are used to reduce the pressure override from the cracking pressure. The pilot piston with small pressurizing area helps to reduce the load force actuated on the spring and makes it possible to reduce the diameter of spring wire. Figure 1 shows the relief valve configuration to which these design concepts are applied. Figure 2 shows the flow-pressure performance of the valve which was calculated via a computer simulation. Figure 3 shows the stable response of pressure. This study presented only the conceptual ideas, and the process of designing and manufacturing prototype valves. The performance of prototype valves will be tested in the future.
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김성동(S. D. Kim),김대명(D. M. Kim),구지석(J. S. Gu),오성진(S. J. Oh),함영복(Y. B. Ham) 유공압건설기계학회 2010 유공압건설기계학회 학술대회논문집 Vol.2010 No.10
It is hard and complex to analytically derive a formula for the volumetric-displacement of a Gerotor pump. An analytical method on the simple formula for calculating volumetric-displacement of a Gerotor pump is proposed in this work, which is relative easy and based upon using length of rotary teeth. The rotary teeth lengths mean the distances from axis of inner rotor or outer rotor to conatact points between inner and outer rotors. The proposed formula is verified through comparison with volumetric-displacement obtained from numerical CAD calculation.