• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.82-92
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• 2011

This paper presents a PFC(Power Factor Correction) system to control the power factor of input current of the converter system which is working in the propulsion system of KTX high speed train. In the KTX train system, initially introduced from ALSTOM, the thyristor converter with phase controlling technique is adopted in the current fed type powering system. The input current induces harmonic losses highly because the waveform becomes rectangular shapes according to the filter inductor current increased as the train speed increasing gradually. Especially the interference with the signalling systems is severe concerned due to high current harmonics on the catenary line. To protect this problem, a frequency trap filter(notch filter) is operating with the input converter system. In this paper, an analysis work and PC simulation have been done on the PFC system to upgrade its performance and maintenance efficiency.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.239-244
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• 2011

Technical advancement in the field of world-class railway has brought the development of passenger safety, efficient operation and fast passenger service. The study of the railway speed-up has been progressed for a long time. As for the speed-up of trunkline railways, its design work has already promoted in some railway tacks and some track sections has already been under construction. In such a perspective we should review if the domestic signaling system is the optimal system and figure out the trend of signaling system for the speed-up that is recently applied over the world. In this way learning about justification and futurition, we should secure the national competitiveness in the long term and review the system available to international exports. Further, it is important to apply the result to the research project currently being pursued. In addition, predicting the recent international trends, we should show the direction of the future-oriented and economic signaling system.

• Coupled systems mechanics
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• 제2권2호
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• pp.159-174
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• 2013

The present work aims at investigating the nonlinear dynamics, bifurcations, and stability of an axially accelerating beam with an intermediate spring-support. The problem of a parametrically excited system is addressed for the gyroscopic system. A geometric nonlinearity due to mid-plane stretching is considered and Hamilton's principle is employed to derive the nonlinear equation of motion. The equation is then reduced into a set of nonlinear ordinary differential equations with coupled terms via Galerkin's method. For the system in the sub-critical speed regime, the pseudo-arclength continuation technique is employed to plot the frequency-response curves. The results are presented for the system with and without a three-to-one internal resonance between the first two transverse modes. Also, the global dynamics of the system is investigated using direct time integration of the discretized equations. The mean axial speed and the amplitude of speed variations are varied as the bifurcation parameters and the bifurcation diagrams of Poincare maps are constructed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1392-1397
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• 2003

This paper deals with a control technique of eliminating the transient vibration of a twin-drive geared mechanical system. This technique is based on a model-based control in order to establish the damping effect at the driven machine part. The control model is composed of reduced-order electrical and mechanical parts. This control model estimates a load speed converted to the motor shaft. The difference between the estimated load speed and the motor speed is calculated dynamically and it is added to the velocity command to suppress the transient vibration generated at the load. This control technique is applied to a twin-drive geared system with backlash. In the previous work, the performance of this control method is examined by simulations. In this paper, the effectiveness of this control technique is verified by experiments. The settling time of the residual vibration generated at the loading inertia can be shortened down to about 1/2 of the uncompensated vibration level.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.80-82
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• 2008

This paper deals with the design of an 870 krpm class high-speed permanent magnet synchronous generator (PMSG) applied to micro turbine system. Since space where the high-speed PMSG coupled with the micro turbine occupies in the system is strictly limited, the work described in this paper is motivated by the desire to make maximum output power of the generator considering the rotor and stator structures, winding methods and bearing system under restricted space.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.374-379
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• 2001

In this paper, a novel design algorithm of speed controller for an Induction motor with the inertia variation is proposed. The main contribution of our work is a very robust, reliable and stable procedure for setting of the PI gains against the specified range of the inertia variation of an induction motor using Kharitonovs robust control theory. Therefore, the basic segment of controller design, the variation of induction motor inertia is estimated by the RLS (Recursive least square) method. PI based speed controller is widely used in industrial application for its simple structure and reliable performance. In addition the Kharitonov robust control theory is used for verification stability of closed-loop transfer function. The performance of this proposed design method is proved by digital simulation and experimentation with high performance DSP based induction motor driving system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.88-93
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• 2001

As the development of High Speed Machining, It is applied in many fields of manufacturing. Among them is to manufacture die and mold. But it still remains as a hard-to-work to apply it in machining pre-hardened materials such as hardened QRO90. It also difficult to machine new materials because there is no machining date of them. Therefore, in this study, we are trying to improve the machinability of new material, QRO90 by applying various cutting conditions, and selecting the best condition which not only reduce the machining time but improve the quality of die and mold made of QRO90 material.

• 신재생에너지
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• 제2권2호
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• pp.37-43
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• 2006

In this paper, the first forecasting system of wind power generation, KIER Forecaster is presented. KIER Forecaster has been constructed based on statistical models and was trained with wind speed data observed at Gosan Weather Station nearby Walryong Site. Due to short period of measurements at Walryong Site for training the model, Gosan wind data were substituted and transplanted to Walryong Site by using Measure-Correlate-Predict(MCP) technique. The results of One to Three-hour advanced forecasting models are consistent with the measurement at Walryong site. In particular, the multiple regression model by classification of wind speed pattern, which has been developed in this work, shows the best performance comparing with neural network and auto-regressive models.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.494_495
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• 2009

This paper presents a study of DFIG wind power generation system for real-time simulation. For real-time simulation, the real-time digital simulator (RTDS) and its user friendly interface simulation software (RSCAD) are used. 2.2MW grid-connected variable speed DFIG wind power generation system is modeled and analyzed in this study. Stator-flux oriented vector control scheme is applied to stator, rotor side converter control, and back-to-back PWM converters are implemented for the decoupled control. The real-wind speed signal extracted by an anemometer is used for realistic and accurate simulation analysis. Block diagrams for DFIG and control scheme of stator, rotor-side are introduced. Real-time simulation cases are carried out and analyzed for the validity of this work.

• 한국기계가공학회지
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• 제5권2호
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• pp.10-15
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• 2006

An introduction to orthogonal cutting model by FEM is given, followed by a review of similar work. The cutting process is treated as quasi-static and strain rate insensitive, so the model is applicable only to low speed cutting operation. Chip separation is accomplished along a predefined cutting path by means of an element death procedure. Contact elements with friction capability are used to model the interaction between the tool and the workpiece. FEM results are compared with cutting experiments with low speed for brass, and good correlations are found.