• Journal of Power System Engineering
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• v.20 no.3
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• pp.36-42
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• 2016

A cylinder control system of the conventional construction machine has been controlled by hydraulic spool valves. This system is low-cost but system efficiency is not high. Recently, to improve this, all valves are controlled electronically and independently. Bu and Yao suggested four way electronic hydraulic control valve system. It is called IMVT(Independent Metering Valve Technology). The purpose of the study is to find proper IMV pressure control method for excavator and to validate excavator's bucket regeneration energy effect by controlling the IMV system. In this paper, we mathematically describe the bucket system of excavator first. And then, based on these results, we design the control system which is divided into two operations(none regeneration or regeneration).The results of the experiment show the desirable performance and usefulness of the designed control system.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.2
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• pp.10-16
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• 2019

In this study, the present regulation of heat metering for the ground source heat pump was investigated. The ground source heat pump has been adopting the heat metering system used in the district heating system for estimating the heating and cooling energy production amount. The accuracy of the present heat metering systems for a water to water ground source heat pump is low, because the system for district heating has a relatively high temperature range comparing with the ground source heat pump operating conditions. Even though the heat amount for the building side should be measured, the heat absorption and extraction amount from or to the ground was measured for the water to air ground source heat pump due to the difficulty of estimating the air side heating and cooling capacity in the present regulation. It is highly recommended to validate the heat metering system to have reliability for the ground source heat pump and develop the system to be applicable water to air ground source heat pump.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1349-1355
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• 2008

The paper shows the analysis of operating conflict of OCGR trip events and metering errors in the photovoltaic generation, wind generation distributed generation customers with no defect of the distributed generation facilities, which are connected to 22.9kV distribution lines. To analyze problems with metering errors and OCGR fault event, a power quality analyzer and PSIM program were used to test the field and to simulate in Sun-Cheon photovoltaic generation and Seo-Cheon photovoltaic generation customers. With the trial distribution line, the result of analysis was verified to prove with the same situation of the actual field. This paper suggests short term and long term countermeasures of OCGR fault events, analysis of over and shortage of metering errors in distributed generation customers.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.101-106
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• 2005

It needs to accumulate a store of know-how on the design, precision processing and appraisement for metering pump which is a kind of gear pump fer synthetic fibers. But the period and cost fur development is not effective, because designers experience many trial and error for the pump design and manufacturing process. Therefore, in order to curtail the period and cut down expenses, the analysis and simulation system is required for a designed metering pump. In this study, the pump simulation software was developed with the visual C++ language and the image processing algorithm, and was investigated through a discharge test for the planetary gear type metering pump.

• Journal of Drive and Control
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• v.18 no.1
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• pp.17-23
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• 2021

The flow signal or spool position signal is used to determine the dynamic characteristics of directional control valves. Alternatively, the signal of spool position or flow can be replaced with the velocity of a low friction, low inertia actuator. In this study, the frequency response of the servo valve equipped with a spool position transducer is measured with a metering cylinder. The input signal, spool displacement, load pressure, and velocity of the metering cylinder are measured, and the theoretical results from the transfer function analysis are verified. The superposition rule for magnitude ratio and phase angle was found to be always applicable among any signal type, and it was found that the load pressure signal is not appropriate for use as the signal for measuring the frequency response of a servo valve. It was confirmed that the frequency response of a servo valve using metering cylinder was similar to the results from a spool displacement signal. The metering cylinder used for measuring the frequency response of a servo valve should be designed to have sufficiently greater bandwidth frequency than the bandwidth frequency of the servo valve.

• Journal of Drive and Control
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• v.17 no.4
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• pp.54-71
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• 2020

In light of the environmental challenges, energy-saving strategies are currently under investigation in the construction industry. This paper focuses on the energy-saving method used in the hydraulic system based on independent metering (IM) technologies, which can overcome the lost energy at the main control valve of the conventional electrohydraulic servo system. By scientifically arranging the proportional valves, the IM system can individually control the flow rate of the inlet and the outlet ports of the actuators. In addition, the IMV system can be used to effectively regenerate energy under different operating modes, thereby saving more energy than conventional hydraulic systems. Therefore, the IMV system has a great potential to improve the energy efficiency of hydraulic machinery. The overall IMV system, including the configuration, proportional valve, operation mode, and the control strategy is introduced via state-of-the-art hydraulic technologies. Finally, the challenges of IM systems are discussed to provide researchers with directions for future development.

• Journal of the Korean Institute of Gas
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• v.24 no.3
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• pp.1-10
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• 2020

This paper describes the development of a smart advanced metering infrastructure(AMI) architecture and services for using smart metering in gas industry. A general gas AMI system is composed of a smart gas meter, IoT network, the AMI platform, and an operation management system with security functions. The proposed gas AMI platform supports two-way communication between smart metering devices and AMI services and is applied by oneM2M standard to support interoperability between various types of metering devices and heterogeneous IoT networks. To demonstrating AMI system with the proposed platform, we installed about 2,900 smart gas meters in real environments and operated AMI systems for one year. We verified that about 94% of gas meters are normally worked and AMI services are stably operated without error or malfunction.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.2046-2052
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• 2016

Ramp metering is one of the most efficient and widely used control methods for an intelligent transportation management system on a freeway. Its objective is to control and upgrade freeway traffic by regulating the number of vehicles entering the freeway entrance ramp, in such a way that not only the alleviation of the congestion but also the smoothing of the traffic flow around the desired density level can be achieved for the maintenance of the maximum mainline throughput. When the cycle of the signal detection is larger than that of the system process, the density tracking problem needs to be considered in the form of the discrete-time system. Therefore, a discrete-time sliding mode control method is proposed for the ramp metering problem in the presence of both input constraint in the on-ramp and exogenous disturbance in the off-ramp considering the random behavior of the driver. Simulations were performed using a validated second-order macroscopic traffic flow model in Matlab environment and the simulation results indicate that proposed control method can achieve better performance than previously well-known ALINEA strategy in the sense that mainstream flow throughput is maximized and congestion is alleviated even in the presence of input constraint and exogenous disturbance.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.51-57
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• 2014

High pressure common rail injection technology has revolutionized the diesel industry. Over the last decade it has allowed engine builders to run higher injection pressures as much as above 1,300bar in order to increase engine efficiency, while reducing emissions. This common rail system has low pressure circuit which is consist of low pressure pump, cascade overflow valve and flow metering unit. The low pressure pump's purpose is to feed fuel oil to the high pressure pump. The cascade overflow valve keeps pressure in front of the metering unit constant and provides lubrication for the high pressure pump. The metering unit, known as the MPROP or fuel pressure regulator, regulates the maximum flow rate delivers to the rail. In this paper, we have investigated the performance characteristics of each components and total low pressure circuit of common rail system.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.56-60
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• 2005

It is necessary to irrigate for agriculture in Korea and agricultural canals play important roles in irrigation. Nowadays gauging water discharge in canals is important because of water shortage in Korea. But It is rare to gauging water discharge in canals. Several water level gauges are installed in agricultural canals through TM/TC. But the abilities of the gauges are insufficient for agricultural water metering. In this situation, we are developing the water discharge metering system which is inexpensive and easy to maintain.