• 전기학회논문지P
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• 제59권1호
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• pp.77-82
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• 2010

This study evaluated the characteristics and reliability of an auger crane with a built-in hydraulic extender. The field test of the hydraulic extender was performed with the hydraulic lines filled with hydraulic fluid and free of air. The pressure generated during the test was measured with a digital pressure gauge. The crane was considered to have undergone one cycle of the excavation process after it had performed excavation under three conditions at the same location. This process was performed three times in total. From the results of the excavation using the hydraulic extender, it was found that the maximum pressure and torque measured were 19.9 [MPa] and 895.4 [$kgf{\cdot}m$], respectively. The rotation force of the auger crane generated at this time signifies a horizontal force. If the excavation diameter of the auger crane is increased, the rotation speed is reduced causing the circumferential speed to also be reduced. The torsional shear stress of the extendable auger crane was calculated to be approximately 23.5 [MPa]. However, the rotation shaft material used for this system was carbon steel for machine structural use (SM45C). Since the minimum torsional yield stress is greater than 150 [MPa] according to KS D 3752, it means the equipment has secured a safety factor greater than 6. Therefore, it was found that when performing work using the extendable auger crane, it exhibited no problems with the safety and reliability of its shaft.

• 상하수도학회지
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• 제29권1호
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• pp.133-138
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• 2015

Pressure retarded osmosis (PRO) process is one of membrane processes for harvesting renewable energy by using salinity difference between feed and draw solutions. Power is generated by permeation flux multiplied by hydraulic pressure in draw side. Membrane fouling phenomena in PRO process is presumed to be less sever, but it is inevitable. Membrane fouling in PRO process decreases water permeation through membrane, resulting in significant power production decline. This study intended to investigate the effect of hydraulic pressure in PRO process on alginate induced organic fouling as high and low hydraulic pressures (6.5 bar and 12 bar) were applied for 24 h under the same initial water flux. In addition, organic fouling in draw side from the presence of foulant (sodium alginate) in draw solution was examined. As major results, hydraulic pressure was found to be not a significant factor affecting in PRO organic fouling as long as the same initial water flux is maintained, inidicating that operating PRO process with high hydraulic pressure for efficient energy harvesting will not cause severe organic fouling. In addition, flux decline was negligible from the presence of organic foulant in draw side.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
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• pp.152-160
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• 2004

Studies to investigate the influence on hydraulic acoustic wave were conducted using pressure swirl atomizer under making frequency range from 0 to 60Hz using water as a propellant. Pressure oscillation from hydraulic sources gives a strong influences on atomization and mixing processes. The ability to drive these low frequency pressure oscillations makes spray characteristics changeable. The effect of pressure perturbation and its spray characteristics showed that low injector pressure with pressure pulsation gives more significantly than high injector pressure with pressure perturbation in SMD, spray cone angle, breakup length. Moreover, this data could be used for prediction of low combustion instability getting G factor.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.228-228
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• 2000

To deal with non-linearities and time-varying characteristics of hydraulic systems, in this paper, the neuro-fuzzy controller has been introduced. This controller does not require an accurate mathematical model for the nonlinear factor. In order to solve general fuzzy inference problems, the input membership function and fuzzy reasoning rules are used for determining the controller Parameters. These parameters are determined by using the learning algorithm. The control performance of the neuro-fuzzy controller is obtained through a series of experiments for the various types of input while applying disturbances to the cylinder. .and performance of this controller was compared with that of PID, PD controller. As a experimental result, it can be proven that the position tracking performance of the neuro-fuzzy is better than that of PID and PD controller.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.165.2-165.2
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• 2011

Flow with suction to water turbine must be in stable state at small hydraulic power plant. But because of water level fluctuation and water gate effect according to irregular supply of cooling water, it would happen to produce bubble and vortex and finally lead to problems in power-plant system. With utilizing the concept design of double size gate, surface water overflowed the overhead of gate for stable flow at suction. We developed the overflow condition and analyzed the design factor with existed one such as water level(overflow amount) and overhead of water gate(overflow figure). Flow test and CFD simulation say that flow have stable state around suction and 20% of wave reduction effect at surface layer after surface water overflow.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.150-158
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• 2002

Through experimental works, the damping force vibration problem was investigated, which results from valve and surge pressure in the oil return line of the hydraulic circuit of an active suspension system in a passenger cu. Experiments were carried out under passive system, where an orifice valve was closed and non-active system, where an orifice valve was opened, using a pressure control valve controlled by solenoid. The effects of parameters of the valve overlap and accumulator on smoothing surge pressure was elucidated. It was proved that the apparent variation of damping force due to the overlap amount of pressure control valve is the most important factor to control the damping force variation. The procedure of the experimental works shows the development process of a proportional pressure control valve in the hydraulics system of an active suspension system of passenger car.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권2호
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• pp.239-245
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• 2013

Modern electric controlled valves are demanded that its solenoid actuator should be smaller size, lighter weight, lower consumption power, and higher response time. For achieving these purposes, the major design factors of solenoid actuator such as magnetic flux density, coil turn numbers, plunger size, bobbin dimension, and etc. are must be optimized. In this study, for optimal design of high speed solenoid actuator for hydraulic servo valve operation, we draw up governing equations which are composed by combination of electromagnetic theories and empirical knowledge, and deduct the values of major design factors by use of them. For more increase the operating speed, voice coil are used as main armature in manufacturing of prototype actuator. And, we have proven the propriety of the governing equations and speed increasing method by experiments using the hydraulic valve assembly adopted the prototype of solenoid actuator.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.401-404
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• 2008

The vegetation in the surrounding area of river is a primary factor to increase water level during flood. The influence of vegetation on the river flow in a bank has been investigated by using a hydraulic experiment. For a hydraulic experiment square-shaped piers are used as a model of unsubmerged rigid vegetation in a open channel. For fully developed uniform flows, the water elevation of the experiment was measured as varying the interval of piers and the porosity which presents the fraction of water flowing area in the cross-sectional area. The Manning's roughness coefficient, which implicates energy losses due to the vegetation, was obtained by using the experimental data. As a result, the energy losses were varied when the distance of piers and the porosity of area were changed, and the Manning's coefficient increased nonlinearly when a water elevation increased.

• 한국산학기술학회논문지
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• 제17권6호
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• pp.39-44
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• 2016

최근의 이상기후로 인하여 수공구조물의 안전성이 재고되고 있으며, 이에 따라 수공구조물의 붕괴에 대한 연구가 증가하고 있다. 특히 제방 등 수공구조물의 월류로 인한 붕괴로 발생하는 홍수파 선단의 초기 이동속도는 제내지의 위험성을 예측하고, EAP(Emergency Action Plan) 등을 수립하는 기초자료가 된다. 이러한 선단홍수파의 정확한 예측을 위해 수리실험이 다수 수행되고 있으나, 많은 연구에서 초기의 홍수파 선단에서 발생하는 표면장력에 의한 축척효과(Scale effect)를 고려하지 않고 있는 실정이다. 이에 본 연구에서는 계면활성제(surfactant)와 영상 분석 장비를 이용한 표면장력 도출 수리실험 및 급 개폐가 가능한 수조를 이용한 홍수파 전파 실험을 통하여, 계면활성제 농도와 표면장력 관계, 표면장력과 홍수파 전파속도 관계, 표면장력과 Weber Number 관계를 도출하여, 초기 홍수파 선단에서 발생하는 표면장력에 의한 축척효과 보정계수 및 축척효과를 받지 않는 한계조건(critical condition)을 제시하였다. 연구결과 Weber Number가 약 12.2 이하일 경우 보정 계수가 필요한 것으로 나타났으며, 그 이상인 경우 축척효과를 무시할 수 있는 것으로 나타났다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.83-89
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• 2000

This paper presents a pressure drop correlation for evaporation and condensation of alternative refrigerant with oil in micro-fin tubes. The correlation was developed from a data base consisting of oil-free pure and mixed refrigerants in micro-fin tube; Rl25 R134a. R32 R410a(R32/R125 50/50% mass), R22, R407c(R32/R125/R134a, 23/25/52% mass) and R32/R134a(25/75% mass). The micro-fin tube used in this paper had 60 0.2mm high fins with a 18 helix angle. The cross sectional flow area $(A_c)$ was $60.8 mm^2$ giving an equivalent smooth diameter$(D_e)$ of 8.8mm. The hydraulic diameter $(D_h)$ was estimated to the 5.45mm. The new correlation was obtained by replacing the friction factor and the tube-diameter in Bo Pierre correlation by a friction factor derived from pressure drop data for a micro-fin tube and the hydraulic diameter, respectively. This correlation was also used to predict some pressure data with a lubricant after using a mixing viscosity rule of lubricants and refrigerants. As a result, the new correlation was also well predicted to the measured data within a mean deviation of 19.0%.