• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.385-388
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• 2001

In this paper, the gearless traction machine drive system using a permanent-maget motor for high-speed elevators is addressed. This application of permanent-magnet motor to the elevator traction machine enables several improvements including higher efficiency, better ride comfort, smaller size and weight, and so on. PWM boost converter is also adopted so that DC-link voltage regulation, hi-directional power flow, and controllable power factor with reduced input current harmonics are possible. To increase reliability and performance, the control board, which can include the car and group controller as well as PWM converter and inverter controller, is designed based on TMS320VC33 DSP The simulator system for high-speed elevators has been developed so that the drive system of high-speed elevator can be tested without my limitation on ride distance and the load condition. Some experimental results are given to verify the effectiveness of the developed system.

• Journal of Institute of Convergence Technology
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• v.3 no.1
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• pp.1-8
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• 2013

High-precision surface actuator, in which in-plane motion is realized by not two-dimensional actuator superposing linear actuators but integrated planar actuator, has been developed to cope with the severe target performance like precise motion with large envelope. It is very difficult to accomplish the performance with the traditional actuating principle. So, various methods have been tried to break through the problem. This paper discusses some meaningful trials performed in the Nano Measurement and Precision Motion Control Lab. of Korea National University of Transportation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.794-798
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• 2002

This paper deals with a moving coil type linear motor for fast access of the miniature ODD. This slim-line motor is composed of the mover supported by guide mechanism, the coil wound into it, and the yoke attached to the permanent magnet for stator. The driving force is generated by the PM of the stator and the current in the coils of the mover. Magnetic circuit analysis and Finite Element Method are applied to estimate the thrust force at air gap. In order to compare the force characteristics between two methods, various experiment results are applied to verify on a prototype. Also the flexible modes of the motor are predicted through the FEM and the structural components are modified to locate this on high frequency region.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.138-141
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• 1999

전류의 손실 없이 MRI 마그네트의 연구전류 운전을 위한 영구전류스위치(Persistent Current Switch;PCS)를 설계 및 제작하여 그 특성을 측정하였다. 한국전기연구소의 Whole body MRI 마그네트로의 적용을 위해 설계되었으며, 또한 PCS 보빈을 기존의 FRP에 비해 열전도 특성과 기계적 강도가 우수한 알루미늄으로 제작하였다. Main 코일 1개와 Shim 코일 9개의 PCS에 대한 필요한 파라미터를 계산하여 제작하였다. PCS의 기본요구조건인 step 형태의 스위칭 특성과 각 PCS가 실온저항의 50%∼55%의 상전도 저항 특성을 보임을 확인하였다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.653-654
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• 2008

This paper presents a topological shape optimization for electromagnetic system using a level set method. The optimization is progressed by updating the implicit level set function from the Hamilton-Jacobi equation. The up-wind scheme is used for numerical implementation of the Hamilton-Jacobi equation. In order to validate the proposed optimization, the core part of a C-core actuator is optimized by three cases using different materials; (single steel), (two steels), and (steel and magnet).

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.23-25
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• 2008

This paper presents a topological shape optimization for electromagnetic system using a Level Set method. The optimization is progressed by updating the implicit Level Set function from the Hamilton-Jacobi equation. The up-wind scheme is used for numerical implementation of the Hamilton-Jacobi equation. In order to validate the proposed optimization, the core part of a C-core actuator is optimized by three cases using different materials; (single steel), (two steels), and (steel and magnet).

• Journal of Korean Vacuum Science & Technology
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• v.7 no.1
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• pp.1-7
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• 2003

The pressure distributions in the test stand built for developing KSTAR NBI ion sources were obtained using a network system composed of conductance elements modeling the ion source, the neutralizer, and other beam line components. The allowable regime was defined on the coordinates of the gas supply rate to the ion source and the neutralizer, considering the proper conditions of the three critical parameters, the ion source pressure for good arc discharge, the pressure integral in the neutralizer for sufficient neutralization, and the chamber pressure for minimum neutral beam loss. The neutral beam evolution along the path from the ion source extraction grid to the calorimeter through the neutralizer, the bending magnet and the vacuum chamber was estimated for typical pressure distributions.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.279-285
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• 2020

An open-end winding (OEW) permanent magnet synchronous motor with dual inverters can synthesize large voltages for a motor with the same DC link voltage. This ability has the advantage of reducing the use of DC/DC boost converters or high voltage batteries. However, zero-sequence voltage (ZSV), which is caused by the difference in the combined voltage between the primary and secondary inverters, can generate a zero-sequence current (ZSC) that increases system losses. Among the methods for eliminating this phenomenon, combining voltage vector eliminated ZSV cannot be accomplished by the conventional Pulse Width Modulation(PWM) method. In this study, a PWM carrier generation method using functionalization to generate a switching pattern to suppress ZSC is proposed and applied to analyze the control influence of the center-zero vector in the switching sequence about the current ripple.

• Proceedings of the Korean DIstribution Association Conference
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• 2003.02a
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• pp.123-166
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• 2003

Marketing channel is recognized as one of the society systems which have the character of functional organization. These organizations are related to each other for specialized and cooperative work. Channel members in distribution channel are striving to accomplish exchange through reciprocal action. Thus channel members exercise their power to take better position in exchange. There will be struggling between members about satisfaction and conflict during this power exercise. Now a days, buyers use more harsh power as large retail firms are increasing. This phenomenon is occurring in the distribution channel. However, there will be different phenomenon in case of agricultural products. Not like industrial product suppliers, agricultural product suppliers have various supply channels and many agricultural products are seasonal. It has also unstable amount supplies. There should be differentiated marketing in agricultural products. Relatively weaker powered suppliers have to strengthen comparative factors and also have to be technically specialized through assessed experience in order to establish strong product sales chain. Making a brand of agricultural product would be also a good idea to increase the product comparability. Channel members need to be recognized their specialized functions in order to make balanced distribution channel. There have to be conversion of concept of relation between suppliers and buyers from subordinate relationship to cooperative relationship.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.1
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• pp.17-22
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• 2016

A voice coil actuator with moving coil type for scanning mirror system of barcode reader has been developed. The actuator has a simple structure including a magnet, a coil and a pin. The performance of the actuator is analyzed by a linearized theoretical model. And the dynamic performance of the proposed actuator is predicted through motor constant and restoring constant obtained by finite element simulations. The theoretical model was verified by the prototype which has 64 Hz resonance frequency and 60 deg reflecting angle. We also discovered that that 3 V input can make the actuator rotate over 61.8 deg reflecting angle at 50 Hz resonance frequency. The proposed actuator can simplify its driving configuration because of its implementation of open-loop control.