• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.179-183
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• 1999

Rubbing occurs when a rotating element comes in contact with a stationary element. In the steam turbines, the rotating element is the rotor while the stationary elements are usually the oil deflectors and packing seals. Rubbing phenomenon may be often obseued on a new or rebuilt machine rather than on a machine that has been operating for several months or years. Rubbing in the turbine has been classified into two modes by the operating conditions: 1) start up or shut down, 2) steady state. At start up or shut down operation, rubbing produces synchronous whirl vibration, which are caused by thermal bow of the shaft due to localized heating on the shaft surface. While subsynchronous whirl vibration is caused by partial rubbing during the steady state operation. In this paper, the two case studies of troubleshooting for excessive vibration caused by rubbing in the actual steam turbines are investigated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1471-1476
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• 2015

Due to the anesthesia process is inappropriate on the operation, awakening state was appeared. To prevent the state, it is necessary to monitor the patients by measuring the depth of anesthesia. In this study, we investigate the possibility of the development of actual surgery available quantitative indicators. The DFA which is included the correlation property of the EEG is used to analysis the depth of anesthesia and bispctrum index. In the results, at the pre-operation, the peak of bispectrum was widely distributed, DFA value was decreased. At the during operation, bispectrum was concentrically appeared in the low frequency area. At the post operation, bispectrum and DFA was both returned to the pre-operation state. We confirmed to be close correlation between the peaks of the bispectrum and DFA value.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.397-400
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• 2015

Due to the anesthesia process is inappropriate on the operation, awakening state was appeared. Because of that patients suffered from severe mental and physical pain. To prevent the state, it is necessary to monitor the patients by measuring the depth of anesthesia. In this study, we investigate the possibility of the development of actual surgery available quantitative indicators. The DFA(detrended fluctuation analysis) which is included the correlation property of the EEG is used to analysis the depth of anesthesia and bispctrum index. In the results, at the pre-operation, the peak of bispectrum was widely distributed, DFA value was decreased. At the during operation, bispectrum was concentrically appeared in the low frequency area. At the post operation, bispectrum and DFA was both returned to the pre-operation state. As a result, we confirmed to be close correlation between the peaks of the bispectrum and DFA value.

• Journal of Power Electronics
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• v.18 no.1
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• pp.129-136
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• 2018

An accurate state-of-charge (SOC) estimation ensures the reliable and efficient operation of a lithium-ion battery management system. On the basis of a combined electrochemical model, this study adopts the forgetting factor least squares algorithm to identify battery parameters and eliminate the influence of test conditions. Then, it implements online SOC estimation with high accuracy and low run time by utilizing the low computational complexity of the unscented Kalman filter (UKF) and the rapid convergence of a particle filter (PF). The PF algorithm is adopted to decrease convergence time when the initial error is large; otherwise, the UKF algorithm is used to approximate the actual SOC with low computational complexity. The effect of the number of sampling particles in the PF is also evaluated. Finally, experimental results are used to verify the superiority of the combined method over other individual algorithms.

• Journal of Power Electronics
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• v.17 no.4
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• pp.1027-1036
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• 2017

The brushless doubly-fed induction generator (BDFIG) is a new type of dual stator winding induction generator. In such a generator, both the power winding (PW) and the control winding (CW) are housed in the stator. This paper presents the performance characteristics of a stand-alone BDFIG operation system. A new T-type steady-state model of a BDFIG is proposed. This model is more suitable for the performance analysis of stand-alone BDFIGs than the conventional Π-type steady-state model and the simplified inner core steady-state model. The characteristics of the power flow and CW current are analyzed by detailed mathematical derivations on the basis of the proposed T-type steady-state model. The analysis results are verified by experiments, which are carried out on a prototype BDFIG. The results of the performance analysis contribute to simplifying the control circuit, improving the control performance, and selecting an appropriate BDFIG for actual industrial applications.

• Journal of the military operations research society of Korea
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• v.25 no.1
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• pp.169-177
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• 1999

There is some limitations for ship to gather weather and sea state information. To make up for this weakness, land organizations can gather the wider variety of information, evaluate the navigational safety on a ship, and supply this information to the ship. In this study, the involuntary speed loss are calculated using the real-time information on weather and considering the increase of resistance induced by wave, and the navigational safety in a seaway is evaluated. The used model for computer simulation is Lpp 93m frigate class ship. The feasibility study is made of using simulation results in actual operation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.153-160
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• 2012

This paper is written for the development of boiler combustion air control algorithm of coal-fired power plant by the steps of design, coding and test. The control algorithms were designed in the shape of cascade control for two parts of air master, forced draft fan pitch blade by standard function blocks. This control algorithms were coded to the control programs of distributed control systems under development. The simulator for coal-fired power plant was used in the test step and automatic control, sequence control and emergency stop tests were performed successfully like the tests of the actual power plant. The reliability will be obtained enough to apply to actual site if the total test has been completed in the state that all algorithms were linked mutually. It is expected that the project result will contribute to the safe operation of domestic power plant and the self-reliance of coal-fired power plant control technique.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.6 no.3
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• pp.57-62
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• 1992

In this paper, the reasonable design standard of Demand Factor for large office buildings is introduced that was made by the statistical way considering actual conditions, such as investigated electrical equipment capacity, electrical power consumption, etc. The results are as follows. 1) It is shown that th saving of electrical equipment investment, the decrease of power loss, the improvement of facilities utilization and the decrease of electrical power rates can be contributed by the application of the design standard. 2) The effect of reduction is showed to confirm the practical use of the proposed reference Demand Factor, and also, it is believed that this proposed reference Demand Factor will be useful in electrical equipment operation and planning.

• Journal of Advanced Marine Engineering and Technology
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• v.12 no.1
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• pp.28-36
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• 1988

Since the oil shocks of 1970s, the quality of the fuel oil for marine diesel engines has become more degarded than ever. When the poorer quality fuel is burned, carbon residues of the fuel oil cause blockage of the fuel injection valve nozzle and troubles of fuel injection system. The mis-firing of engine occurs due to the decrease of fuel quantity injected, the decrease of compression pressure in the slow speed range, the increase of fuel leaked and the high ignition temperature of degraded fuel etc. This paper is to investigate theoretically the effects of mis-firing on the crankshaft axial vibration of diesel engine. The cylinder pressure in operation is calculated by the computer aided simulation of closed cycle for a large two-stroke diesel engine and also the exciting force of axial vibration and the resonance amplitudes are calculated. And then, the condition of normal state, misfiring and one-cylinder cut-off operation are analyzed. The results of calculations show good agreements with those of the actual measurements.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.3
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• pp.60-71
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• 1989

In this paper the structure of an engine and its interaction are investigated by a mathematical model for the performance evaluation. The total system is composed of air-fuel inlet element, intake manifold, combustion, engine dynamics and emission. Their control functions are schematically evaluated. Because of the model constructure with general engine functions and computer simulation of the chosen engine, physical characteristics of the corresponding engine and the engine data of normal operation states are used. According to the study, it is possible to predict the mixture rate by the difference in the mass of fuel and air flowing into cylinder and to evaluate and trace dynamic characteristic of operation state under various operating conditions. The model characteristic under the transient operating condition to evaluate operating of actual engine through the result of simulation.