• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.71-78
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• 2007

Input shaping is known to be a very effective tool for suppressing residual vibration without introducing any complicated sensors and feedback control. Real-time input shaping schemes necessitate a process such that the input command is discretized to deal with non-prescribed, real-time input. Thus parameters associated with input command discretization, such as time spacing and duration time, are unknowns which affect the performance of input shaping schemes, especially for small and fast XY stages. This paper investigates the effects of input command discretization parameters, such as time spacing and duration time, on the dynamic performance of XY stages subjected to real-time input shaping. An experimental system is developed which is equipped with an XY stage driven by servo-motors and real-time user command. Experiments are performed to investigate the dynamic performance of XY stage by changing these parameters and to yield a strategy to gain better performance.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.83-90
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• 2008

Input shaping is an efficient tool to eliminate transient and residual vibration caused by motion of mechanical systems. However, the rise time of the systems tends to increase due to the presence of input shapers. This paper is concerned with the rise time reduction when using input shaping. To this end, this paper proposes an input shaper design method for an undamped single mode vibration system using a virtual mode, which is not an actual mode but reflected in the design process. The essence of the proposed method is to design a three-impulse input shaper as if a single mode system has two modes: one actual mode and one virtual mode. The natural frequency of the virtual mode is a design parameter to change the rise time of the system. This paper discusses the performance of the proposed input shapers by simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1902-1910
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• 2009

This paper presents a graphical windows-based program for the education and training for novel network reduction. The object of developed simulator is to provide users with a simple and useable tool for gaining an intuitive feel for power system analysis. The developed simulator consists of the main module (MMI,GUI), the location marginal price module (LMP), the clustering module and network reduction module. Each module has a separate graphical and interactive interfacing window. The developed simulator needs with the PSS/E input data format, generator cost function, location information. Line admittances of reduced network was determined by using the power flow method(Newton-Raphson). So line flow of reduced network is almost same to original power system. Results of reduced network are compared on the window in the tabular format. Therefore, the developed simulator can be utilized as a useful tool for effective education and training for power system analysis.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.717-724
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• 2013

Industrial cranes are indispensable equipment in heavy industry. However, unwanted vibrations in cranes often cause accidents. Input shaping is widely accepted as a useful tool for removing residual vibration in cranes. A unity magnitude zero vibration (UMZV) input shaper is often used for cranes driven by on-off-type motors. However, although a UMZV input shaper minimizes residual vibration, the input shaper cannot prevent the crane from moving slightly further than expected from the original command. This paper describes an improved method of input shaping that can compensate for position inaccuracies, as well as remove the residual vibration of cranes. Experiments were performed to validate the proposed input-shaping method, illustrated through numerical simulations.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.556-559
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• 2001

In this paper, we proposed AC/DC boost converter to improve input current harmonic reduction in SMAW(shielded metal-arc welding). The proposed harmonic reduction with the boost converter design and the UC2854 integrated circuit which controls the converter, The topology of welding power supply is made of a pair of boost converter and welder half-bridge IGBT inverter. The voltage arc is modeled by a variable resistance in series with a voltage source. The results has been confirmed by PSIM simulation tool. The simulation results show that input at current is nearly sinusoidal with low harmonic contents and sinusoidal input current waveform at high power factor.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.19-25
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• 2019

We have developed a tool that uses finite element analysis (FEA) to rapidly evaluate a shaft-bearing system of machine tools. We extracted commercial data on suitable clamping units and defined the inner profile of the shaft to avoid needing direct user input to define the profile. We use a splitting algorithm to convert the shaft into beam elements with two diameters and length. To validate the tool, we used it to design and evaluate a shaft-bearing system and found that our tool automated the construction of an FE system model in a commercial FEA package as well as the static stiffness evaluation; both tasks were completed in seconds, demonstrating a significant reduction from the minutes normally required to complete these tasks manually.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1011-1017
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• 2011

Servo control loops are a core part in the control architecture of machine tools. Servo control loops manage acceleration, velocity and position of all the axes in a machine tool based on commands. The performance of servo control loops sets the basis for quality of production paris and cycle time reduction. First, this paper presents a general control architecture of machine tools and several control schemes in literature, which can be applicable to machine tools control; including Zero Phase Error Tracking Control (ZPETC) and Cross Coupling Control (CCC). After that, modem control strategies to mitigate the problem of high speed machining are reviewed. In high speed machining, high accelerations excite the machine structure up to high frequencies, thereby exciting the structure's modes of vibration. These structural vibrations need to be damped if accurate positioning or trajectory following is required. Input shaping is an attractive option in dealing with structural vibrations. The advantages and drawbacks of using input shaping technique for machine tools are discussed in detail.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.1
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• pp.81-88
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• 2011

The method is introduced for estimating the noise source contribution on the noise of PDP TV in a multiple-input system where the input sources may be coherent with each other. By the coherence function method, it is found that the biggest part of the noise source in the PDP TV noise is generated by the PCB boards which consume high power and produce high heat. This analysis is modeled as three-input/single-output system because the noise is generated by three main boards, X-board, Y-board, SMPS that are located close to each other. The coherence function method is proved to be useful tool for identifying of noise source. In this study, Transfer Path Analysis using MDSA is implemented to determine the quantitative noise contribution of each board for PDP TV with the rear case closed and with the rear case open. And the possibility of noise reduction is confirmed through the experimental method that isolates the most contributing board by adding sound-absorbing materials to it.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.198-201
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• 2005

Monobloc technology Provides a homogeneous material along the complete tubular shaft without any discontinuity between the interconnecting tube and the stems as is found when the tubes and stems have been Joined by welding. Cold tube drawing is a technique that can be applied for manufacturing of those monobloc tubular shafts with several advantages such as high productivity and cost reduction. The present study is concerned with the investigation about the process parameters related with tool configuration. In order to obtain successfully formed SIS(Steering Input Shaft) without any defects, advanced design of mandrel is presented and analyzed by the FEM and ductile fracture criterion in this paper.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1285-1289
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• 2004

Elman Discrete Recurrent Neural Networks Model(EDRNNM) was used to be a suitable short-term hydrological forecasting tool yielding a very high degree of flood stage forecasting accuracy at Musung station of Wi-stream one of IHP representative basins in South Korea. A relative new approach method has recurrent feedback nodes and virtual small memory in the structure. EDRNNM was trained by using two algorithms, namely, LMBP and RBP The model parameters, optimal connection weights and biases, were estimated during training procedure. They were applied to evaluate model validation. Sensitivity analysis test was also performed to account for the uncertainty of input nodes information. The sensitivity analysis approach could suggest a reduction of one from five initially chosen input nodes. Because the uncertainty of input nodes information always result in uncertainty in model results, it can help to reduce the uncertainty of EDRNNM application and management in small catchment.