• Journal of Mechanical Science and Technology
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• v.20 no.7
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• pp.972-980
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• 2006

In general, to send out natural gas via a pipeline network across the nation in LNG terminal, high-pressure cryogenic pump supply highly compressed LNG to high-pressure vaporization facilities. The Number of cryogenic pumps determined the send-out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high vibration at cryogenic pumps-motor system in LNG terminal, vibration spectrum analysis and motor current signature analysis have been performed together. Through the analysis, motor rotor bar problems are estimated by the vibration analysis and confirmed by the current analysis. So, it is demonstrated through the case study in this paper, how performing vibration analysis and current signature analysis together can reliable diagnosis rotor bar problems in pump-motor system.

• The KSFM Journal of Fluid Machinery
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• v.7 no.1 s.22
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• pp.51-57
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• 2004

The waterhammer has recently become more important because the pumping stations were big and the systems conveying the fluid through the large and long transmission pipelines were complex. When the pumps are started or stopped for the operation or tripped due to the power failure, the hydraulic transients occur as a result of the sudden change in velocity As the pressure waves are propagating between the pumping station and the distributing reservoir, the pressure inside the pipe drops to the liquid vapor pressure with the pipeline profile, at which time a vapor cavity forms, and finally the column separation occurs. If the pressure in the pipe is less than the atmospheric pressure, the pipe can be collapsed and destroyed after the water columns separated by the vapor cavity rejoin. During the reverse flow, the pressure is so abnormally increased at the pumping station that the accident of flooding may happen due to the failure of system. In this paper, the field tests on the waterhammer by the startup, stoppage, and power failure of a centrifugal pump were carried out for Yongma transmission pumping station in Seoul. The experimental results were compared with that of the numerical calculations, in which results the procedure of controlled pump normal shut-down and the two-step closing mode of controlling the ball valve for pump emergency stop are proposed to reduce the pressure surge.

• Journal of the Korean Society of Safety
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• v.26 no.1
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• pp.1-7
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• 2011

When the pumps stopped in the operation by the power failure, the hydraulic transients take place in the sudden change of a velocity of pipe line. Each and every water hammer problem shows the critical stage to be greatly affected the facts of safety and reliability in case of power failure. The field tests of the water hammer executed at Cheong-Yang booster pump station having an air chamber. The effects were studied by both the practical experiments and the CFD(Computational Fluid Dynamics : Surge 2008). The result states that the system with water hammering protection equipment was much safer when power failure happens. The following data by a computational fluid dynamic analysis are to be shown below, securing the system stability and integrity. (1) With water hammering protection equipment. (1) Change of pressure : Up to $15.5\;kg/cm^2$ in contrary to estimating $16.88\;kg/cm^2$. (2) Change rate of water level : 52~33% in contrary to estimating 55~27%. (3) Note that the operational pressure of pump runs approx. 145 m, lowering 155 m of the regularity head of pump. (4) Note that the cycle of water hammering delays from 80 second to 100 second, together with easing the function of air value at the pneumatic lines. (2) Change of pressure without water hammering protection equipment : Approximate $22.86\;kg/cm^2$. The comprehensive result says that the computational fluid dynamics analysis would match well with the practical field-test. It was able to predict Max. or Min. water hammering time in a piping system. This study aims effectively to alleviate water hammering in a pipe line to be installed with air chamber at the pumping station and results in making the stability of pump system in the end.

• Journal of Power System Engineering
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• v.9 no.2
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• pp.45-49
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• 2005

Liquefied natural gas takes up six hundredths of the volume of natural gas, which makes storage and transportation much easier. To send out natural gas via a pipeline network across the nation, high-pressure LNG pumps supply highly compressed LNG to high-pressure vaporization facilities. The Number of high-pressure LNG pumps determined the send-out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high beat vibration at cryogenic pumps, vibration and motor current signal analysis have been performed. High vibration of cryogenic pumps could be reduced due to the modification of motor rotor.

• The KSFM Journal of Fluid Machinery
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• v.8 no.5 s.32
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• pp.22-28
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• 2005

As the water supply facilities are recently getting larger, the domestic waterworks become multi-regional water supply system. Large water supply facilities generally consist of the intake pumping station, water treatment plant and water supply/distribution facilities. Although the pumping stations and the pipeline systems are used to pump up water, it often happens pipeline damage and flooding accident by the water hammer. In this paper, the intake pumping station is guaranteed by both the computer simulation and the field test analysis. This study is contributed to the safe operation program for the pumping station in which results of the adjustment on the safety plan of the pumping station, the air valve and the valve closing time.

• Journal of Energy Engineering
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• v.17 no.3
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• pp.139-144
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• 2008

Recently due to march as the high oil price, It is necessary for Korea to grope a plan, which is to increase the energy efficiency of existing facilities as well as to develop overseas gas and oil resources. With this point, this work carried out to approach the high pressure LNG pipeline network of Inchon receiving terminal with Newton method as corrective flowrate. We found that the high pressure network mainly depends on FCVs(Flow Control Valves). The high pressure pump showed the maximum efficiency at the FCVs of 50% opening and could discharge LNG only above the LNG head of 1,500m from a system curve obtained. The operating cost of pumps was estimated from their operating points. We compared the operating cost under normal operation with the operating cost under maximum efficiency. Especially, we obtained the day savings of a year as wells as the hour savings of a day. From the results, the high pressure network win be able to reduce the operating cost of 138 million wons in a year. This means that a pump can reduce the operating cost of 9,823 thousands won. Consequently, this work could find the operating features of the pumps under the complicated high pressure LNG network and the savings effect of the pump operating cost. Also, the results will be able to macroscopically contribute the heightening of national energy competitiveness as well as to microscopically contribute the future effective operation of LNG receiving terminal.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.90-96
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• 2017

When the hot water is supplied through the district heating (DH) pipeline, a pressure differential control valve (PDCV) protects the DH user equipment from the high pressure DH water and helps to supply DH water to long distance. It also controls the temperature and adjust the pressure in the main district heating pipeline. However, cavitation occurs in PDCV due to the use of high pressure DH water. It causes frequent failures and many problems. It also causes energy loss and complaints to both operators and users. In order to solve these problems, we will introduce the energy saving technology to replace the primary side PDCV with hydraulic turbine, convert the differential pressure into electricity, and utilize electricity as the power of the secondary side pump.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1144-1147
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• 2017

It was reviewed about the pressure oscillation on the inlet of turbo-pump at the moment of engine startup and shutdown. Specially, This research was performed how much is the effect of PSD(Pogo Suppression Device) about the pressure oscillation on the inlet of turbo-pump at the moment of engine startup and shutdown. For analysis, propellant tank PSD and Engine are modelled with Flowmaster which is the commercial 1D program. As the analysis results, even though the PSD is installed in the pipeline, the pressure drop or rising at the moment of engine startup and shutdown is same compared to the case without PSD. However, it was confirmed that PSD reduces the pressure oscillation of the high frequency band as the original purpose of PSD.

• Journal of the Korean Geosynthetics Society
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• v.15 no.1
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• pp.71-81
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• 2016

To evaluate the effects of magnetic force for transporting the dredged soil, magnetic energy inducing device was installed at the dredger. The whole length of transporting pipeline reaches more than 8.5km and the efficiency of the system and the characteristics of the flow are critical factors. The main parameters which govern the flow are flow-rate, velocity, concentration and slip-layer's condition, so in the field test monitoring system was applied to check the real time conditions of the closed circuit flow and the main parameters. From analyzing the relation between the dredged soil amounts and the pump power, it can be concluded that the magnetic forces effect on the transporting system, increase the transporting quantities of dredged soil and decrease power consumption of the pump.

• Journal of Energy Engineering
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• v.28 no.1
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• pp.22-29
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• 2019

A heat pump system using wasted heat from thermal effluent to supply the heating energy can reduce energy consumption and emissions of greenhouse gases by greenhouse facilities nearby. The Jeju National University consortium constructed a heat pump system using the thermal effluent from the Jeju thermal power plant of KOMIPO to provide with cool or hot water to greenhouse facilities located 3 km from the power station. In this paper, the system configuration of the heat pump system was summarized, and the results of operations for demonstration of a heating performance carried out during the winter season in 2018 were investigated. The preoperational tests proved that the water temperature drop through the pipeline transporting extracted heat was less than $2^{\circ}C$. The COP (coefficient of performance) of the heat pump was higher than 4.0, and hot water with the maximum temperature of $50^{\circ}C$ could be supplied to greenhouse facilities by utilizing wasted heat from thermal effluent.