• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.128-130
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• 2003

For electrical machine designers, core loss data are usually provided in the form of tables or curves of total loss versus flux density or frequency. The aim of this work is to propose a mathematical model for the iron losses prediction in soft magnetic material$ with any frequency and flux density. In this paper, three formulas for calculating the iron loss coefficients are discussed. And the coefficients are applied to calculate the iron loss of the 25kW high speed motor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.31-33
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• 2007

Cost reduction requires lowering number of power devices used in the converter driving SRM. This is quite feasible in SRM drive systems than in other drive systems. This paper deals with design, analysis, and simulation of such a novel two phase SRM. A novel two phase SRM has high performance, self-starting capability, high efficiency, and low manufacturing cost. Additionally, the stator back iron does not experience any flux reversal as the flux is in the same direction whether phase A or B is excited leading to a greater reduction in core losses. The magnetic analysis and design considerations of the novel two phase SRM have been obtained by the finite element analysis (FEM). Experimental verification of the machine design is provided to correlate with analysis and simulation studies.

• 산업공학
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• 제16권2호
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• pp.248-257
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• 2003

In a heated rolling process of a steel mill where steel plates are pressed to a sheet coil by spreading and expanding, an irregularly-shaped head portion as well as a tail portion of the sheet coil need to be cropped. Any crop which is not clearly cut and separated from the sheet coil may cause critical damages to the facilities of the following processes. As the cropping process is performed very fast, human eyes are not proper for continuous monitoring of the cropping process. To solve this problem, we have developed a machine-vision based crop-drop detection system. The system also measures lengths of major and minor axes for the crops and thereby determines the proper crop size to minimize steel sheet losses.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 추계종합학술대회
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• pp.634-637
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• 2000

A diagnosis system that provides early warnings regarding machine malfunction is very important for rolling mill so as to avoid great losses resulting from unexpected shutdown of the production line. But it is very difficult to provide early warnings in rolling mill. Because dynamics of rolling mill is non-linear. This paper shows a chaotic behaviour of vibration signal in rolling mill using embedding method. Not only phase plane and Poincare map are implemented but also FFT and histogram of vibration signal in rolling mill is presented by embedding method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 추계학술대회 논문집
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• pp.39-40
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• 2014

In this paper, a novel 12/8 segmental rotor type switched reluctance motor (SRM) is proposed. Different from conventional structures, the proposed rotor consists of a series of discrete segments, and the stator is constructed from two types of stator poles: exciting and auxiliary poles. Moreover, in this structure short flux paths are taken and no flux reverse exists in the stator. While the auxiliary poles are not wound by the windings, which only provide the flux return path. Compared with conventional 12/8 SRM, the proposed structure increases the electrical utilization of the machine and decreases the core losses, which may lead to high efficiency. To verify the proposed structure, finite element method (FEM) is employed to get static and dynamic characteristics. Finally, a prototype of the proposed motor is tested for characteristics comparisons.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.95-99
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• 1994

Robot engineering is developed mainly in the field of intelligibility such as a manipulation. Considering the popularization of robots in the future, however, a robot should be studied from a viewpoint of saving energy because a robot is a kind of machine with a energy conversion. This paper deals with minimizing an energy consumption of a manipulator which is driven in a point-to-point control method. When a manipulator carries a heavy payload toward gravitation or the links are de-accelerated for positioning, the motors at joints generate electric energy. Since this energy can be regenerated to the source by using a chopper, the energy consumption of a manipulator is only heat loss by an electric and a frictional resistance of the motors. The minimization of the sum of these losses is reduced Lo a two-points boundary-value problem of an non-linear differential equation. The solutions are obtained by the generalized Newton-Raphson method in this paper. The energy consumption due to the optimum angular velocity patterns of two joints of a two-links manipulator is compared with conventional velocity patterns such as quadratic and trapezoid.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.38-45
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• 2012

A novel kind of switched reluctance motor (SRM) with short flux path is proposed in this paper. Phase excitation in the SRM gives short flux paths, hence reducing the magnetomotive force required to drive the machine, resulting in significant reduction of copper wire and core losses compared to the typical SRM with diametric circulation of magnetic flux. To verify the performance, the characteristics analysis of a double-stator SRM, a 6/5 SRM with C-core structure, and a 4/5 two-phase SRM, which all have short flux paths, and a comparison with conventional SR motors are executed. The comparison demonstrates that the proposed motor offers some advantages in terms of torque and efficiency.

• Journal of Magnetics
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• 제17권4호
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• pp.280-284
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• 2012

This paper presents a method for evaluating interior permanent magnet synchronous motor (IPMSM) performance over the entire operation region. Using a d-q axis equivalent circuit model consisting of motor parameters such as the permanent magnetic flux, copper resistance, core loss resistance, and d-q axis inductance, a conventional mathematical model of an IPMSM has been developed. It is well understood that in IPMSMs, magnetic operating conditions cause cross saturation and that the iron loss resistance - upon which core losses depend - changes according to the motor speed; for the sake of convenience, however, d-q axis machine models usually neglect the influence of magnetic cross saturation and assume that the iron loss resistance is constant. This paper proposes an analysis method based on considering a magnetic cross saturation and estimating a core loss resistance that changes with the operating conditions and speed. The proposed method is then verified by means of a comparison between the computed and the experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2347-2349
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• 2004

The iron loss in electric machines takes large part of machine losses and the reduction of iron loss brings the increase of the efficiency. In the rotating machines, however it is very difficult to calculate result because the measuring processes are very complex and laborious. As is well known, the relation between the flux density B and the magnetic field intensity H relation is not linear. For the iron loss, B and H must be measured and usually B becomes the reference wave(sine wave) and the following H is measured using H-coil. To make the B as sine wave, B is controlled by some devices. The error is controlled to become zero by the proposed algorithm which uses the bisection algorithm. The experiments are compared with the simulation results, and they show acceptable agreements.

• 한국정밀공학회지
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• 제17권5호
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• pp.108-115
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• 2000

This paper presents a variant type process planning system for machining of dies for auto-body production. Through the analysis of dies and their manufacturing processes, the authors categorized the press dies into 15 groups according to the similarity of machining features. After critically reviewing current manufacturing procedures, a standard process plan was defined for each group. The authors present MP3D the process planning system built on the standard process plan database, and show how they apply it at the die manufacturing plant of an automobile company. MP3D is expected to reduce major losses in machining such as reworking caused by mistakenly uncut features and eventually to help to accumulate the knowledge of operators. The operation sheet MP3D produces is also used in monitoring the progress of manufacturing of dies. This paper explains the whole development cycle of a process planning system from process analysis to application so that it can help readers to develop and apply a process planning system to their machine shops.