• Journal of Korean Society of Water and Wastewater
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• v.21 no.2
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• pp.177-185
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• 2007

Hydraulic efficiency($T_{10}/T$) in clearwell is often estimated by L/W ratio. However, this estimation is not accurate because other factors which give an effect on hydraulic efficiency such as shape of basin, diffuser wall and intra-basin is ignored. Therefore, in this research, hydraulic efficiency is predicted by the quantitative analysis of dead zone using CFD simulation in a pilot scale clearwell. The results show that the reason why higher L/W ratio increase the hydraulic efficiency is to decrease the dead zone of linear region which is located between baffles. Diffuser wall or intra-basin also affects on hydraulic efficiency with this process. Also, we conclude that hydraulic efficiency can not be reached to 0.8 or higher.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.546-551
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• 2004

An applying Thermodynamic method for the purpose of measuring hydraulic efficiency of pump-motor system, based on IEC60041 code, is not easy to adopt at field test. Even though there were splendid development in measuring technic in discharge measuring through the hydraulic machina lots of unsolved problems concerned in flow-rate are still remain in measuring hydraulic efficiency in hydraulic machine. The key point in measuring hydraulic efficiency is to measure exact flow-rate. So, Thermodynamic methode provides a good solution. This methode measures hydraulic efficiency by detecting the difference of temperature and pressure between the hydraulic process of machine, without measuring flow-rate of pump or turbine. By measuring temperature in mk level and absolute pressure in pascal, we can get a difference of thermodynamic specific energy in Moliere chart before and after of hydraulic process, md that difference is equal to hydraulic loses. Following the standard in proceeding Thermodynamic methode, I hope these trial and records make others be familiar to the thermal methode and make it easer to beginner for trial.

• Journal of Drive and Control
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• v.11 no.4
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• pp.39-45
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• 2014

With recent oil price increases, the fuel efficiency of hydraulic excavators has become a serious issue. Researchers have considered weight lightening by high pressurization in order to improve the efficiency of the excavator and pump controlled actuation (PCA) and to reduce pressure loss of hybrid and valves using mechanical inertia. However, high pressurization is not very effective because the excavator operates at a low speed; a hybrid is inefficient because little accumulated inertial energy is accumulated; and PCA is ineffective because control precision and responsibility are low. In this study, a method to minimize air and gas in hydraulic oil has been presented as a simple and new way to increase hydraulic efficiency.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.855-863
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• 2019

The efficiency of fishway installed in rivers can be directly evaluated by means of fish monitoring. On the other hand, when it is difficult to monitor the fish in certain conditions, or when planning a fishway, the efficiency can be evaluated indirectly through the hydraulic analysis. In this study, the hydraulic analysis technique for evaluating the efficiency of a fishway was presented. The River-2D model with the fish physical habitat module was used for the analysis of the attraction efficiency, and the weighted usable area was proposed as an index of the efficiency. In the analysis of passage efficiency, the three-dimensional model, Flow-3D, was used as an evaluation tool to describe the fluid behavior on a hydraulic structure with free surface. The ice-harbor type fishway at Baekgok weir in the Deokcheon River was selected as a test-site, and the efficiency was estimated using the hydraulic analysis. And then it was compared with fish monitoring data acquired from the river. As a result, it is difficult to replace the hydraulic analysis results with the efficiency quantitatively, but it can help to grasp the general tendency.

• Transactions of The Korea Fluid Power Systems Society
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• v.3 no.4
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• pp.1-7
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• 2006

A water hydraulic pump is likely to have serious problems of high leakage, friction and low energy efficiency. A water hydraulic pump has commonly a fixed displacement type and its outlet flow is adjusted by controlling rotation speed of the pump, which can be implemented by using an electric inverter. This study aims to investigate energy efficiency of the water hydraulic pump system which is driven by an electric inverter. The study is based on the experimental results. The pump which is used in the study shows relatively good efficiency and low leakage, low friction as well. The reasons for the good performance of pump is also investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.2
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• pp.195-201
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• 2015

An electric excavator consumes battery energy to drive an electric motor attached to a hydraulic pump to generate hydraulic power. In a conventional hydraulic excavator, the hydraulic pump is controlled by regulators, which are used to optimize the diesel engine efficiency. Because of a lack of battery energy capacity, an electric excavator controller should consider not only the electric motor efficiency but also the hydraulic pump efficiency. Thus, electric motor and hydraulic pump efficiency maps were constructed. An optimal operating map (OOM) was created based on the most efficient operating points under each input condition. An integrated control algorithm controlled the speed of the electric motor and displacement of the hydraulic pump according to the OOM. To confirm the utility of this algorithm, a model-in-the-loop simulator for the algorithm with an electric excavator was established. The simulation results showed that the integrated control algorithm improved the energy efficiency of an electric excavator.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.282-285
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• 1997

The torque efficiency of oil hydraulic pump is an important factor for it's performance characteristics. A study on the performance test method of oil hydraulic pump is based on test standard, but there is to be desired an study for double or tandem type oil hydraulic piston pump. So in this study present a test method on the tandem pump for torque efficiency and analysis method of the results.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.5
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• pp.46-55
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• 1994

The purpose of this research is to construct experimental test set-up and to establish a series of performance test program for the domestically developed hydraulic couplings, and to provide a software to store and utilize these experimental data which can be used to improve the performance of the hydraulic coupling and solve the job problems confronted during operation. The performance test consists of measurement of torque, rpm and efficiency of the hydraulic coupling for three different amounts of working fluid with various loads to the output shaft, and investigating the torque, rpm and efficiency characteristics with respect to these parameters. The results of this study can contribute to the development of variable speed hydraulic coupling and torque converter pursued by the domestic industry.

• Journal of Powder Materials
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• v.17 no.6
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• pp.456-463
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• 2010

This paper describes the results of the application of Cr-Diamond-like carbon (DLC) films for efficiency improvement through surface modification of spur gear parts in the hydraulic gear pump. Cr-DLC films were successfully deposited on SCM 415 substrates by a hybrid coating process using linear ion source (LIS) and magnetron sputtering method. The characteristics of the films were systematically investigated using FE-SEM, nano-indentation, sliding tester and AFM instrument. The microstructure of Cr-DLC films turned into the dense and fine grains with relatively preferred orientation. The thickness formed in our Cr buffer layer and DLC coating layer were obtained the 487 nm and $1.14\;{\mu}m$. The average friction coefficient of Cr-DLC films considerably decreased to 0.15 for 0.50 of uncoated SCM415 material. The hardness and surface roughness of Cr-DLC films were measured 20 GPa and 10.76 nm, respectively. And then, efficiency tests were performed on the hydraulic gear pump to investigate the efficiency performance of the Cr-DLC coated spur gear. The experimental results show that the volumetric and mechanical efficiency of hydraulic gear pump using the Cr-DLC spur gear were improved up to 2~5% and better efficiency improvement could be attributed to its excellent microstructure, higher hardness, and lower friction coefficient. This conclusion proves the feasibility in the efficiency improvement of hydraulic gear pump for industrial applications.

• Journal of Drive and Control
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• v.16 no.4
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• pp.1-8
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• 2019

The HPM (High-speed Power Matching) system is an electro-hydraulic control system. It directly controls the swash plate of the pump by selecting four-loop logic based on joystick signals, pump flow, and pressure signal to improve the efficiency and controllability of construction machines. In the NFC (Negative Flow Control) system, a typical pump control system using conventional open center type MCV, the loss is continuously generated by flow through the center bypass line even when the excavator is not in operation. Also, due to the slow response of the pump that indirectly controls the flow rate using the pressure regulator, peak pressure occurs at the start or stop of the operation. Conversely, the HPM system uses an MCV without center-by-pass flow path and the swash plate of a pump for the HPM is controlled by a high-speed proportional flow control valve. As a result, the HPM system minimizes energy loss in standby state of the excavator and enables peak pressure control through rapid electro-hydraulic control of a pump. In this paper, the concept of the HPM system algorithm is introduced and the hydraulic system efficiency is compared with the NFC system using the excavator SAT (System Analysis Tool).