• Research in Mathematical Education
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• v.16 no.1
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• pp.31-50
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• 2012

The present study explored whether the implementation of focused activities (intervention programme) can enhance 22 pre-service mathematics teachers' proficiency in solid geometry thinking level as well as change for the better their feelings in this discipline. Over a period of 6 weeks the pre-service teachers participated in activities and diversified experiences with 3D shapes, using illustration aids and actual experience of building 3D shapes in relation to the various spatial thinking levels. The research objectives were to investigate whether the intervention programme, comprising task-oriented activities of solid geometry, enhance mathematics pre-service teachers' mastery of their geometric thinking levels as well as examine their feelings towards this discipline before and after the intervention programme. The findings illustrate that learners' levels of geometric thinking can be promoted, entailing control on higher thinking levels as well as a more positive attitude towards this field.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2009.11a
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• pp.162-167
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• 2009

With the introduction of the ubiquitous technology, the housing culture centers of construction companies have demonstrated future housing image and technology. However, ubiquitous home services are technology oriented items. The purpose of this study was to identify u- services which were realized in domestic future housing and to compare those with services the residents needed greatly refer to researches related to demand for u-service. For this study, field studies were conducted with 3 domestic future housings and precedent studies on demand for u-service were analyzed according to the standard of residents' demand. The results of the study showed that residents prefer u-services for security and control of indoor environment for housework and leisure life. As a result, u-services which residents needed mainly did not correspond with those that were displayed in future housing.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1654_1655
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• 2009

영구자석형 스테핑 모터 (Permanent Magnet Stepping Motor, PMSM)에서는 그 구조적 특징으로 인하여 필연적으로 코깅 토크 (cogging torque)가 발생한다. PMSM의 성능을 저하시키는 코깅 토크를 제거하기 위하여 Internal Model Principle (IMP)을 제안하였다. IMP를 사용하기 위해 Field-Oriented Control (FOC) 기반의 SISO 시스템을 구성하고 IMP를 PI 제어기에 병렬로 추가하였다. 모의 실험 결과로 코깅 토크로 인한 속도 리플이 효과적으로 제거됨을 보였다.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1135-1137
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• 2001

본 연구는 자계방향 기준 벡터제어 이론에 기초하여 속도 센스리스 벡터제어를 구현한다. 벡터제어는 상태량에 기초한 MRAS (MRAS: Model Reference Adaptive System)방법은 이득정수의 결정이 어려운 결점을 가지고 있다. 여기서는 관측기 이론에 기초하여 2차자속 관측기와 전류센스에서 검출한 전류값으로 속도추정을 행하는 새로운 속도 추정법을 제안한다. 그리고 제안한 방법이 자계 방향 벡터제어 시스템의 실현에 가능성이 있음을 시뮬레이션으로 검토한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.374-379
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• 1992

The automation system oriented as one of the second year automation projects for the small and medium sized enterprises(SME) was developed for the improvement of the production rate and cut the required manpower in the field of the relay which is one of the small electric components used in various industrial fields. The objectives of this study are not only improving the international competition of the relay itself but also partially solving the technical and financial porblems featured by common bottlenecks of the SME for effecient assembly automation. For the purpose of these objectives, several topics are studied as followings. -. Analyzing the adjustment process and determining the specification of the automation system. -. Determining the layout for the automation system to meet the determined specification. -. Detail design ofthe automation system for relay adjusment and inspection. -. Control system design. -. Automation system development and performance test.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.974-975
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• 2008

영구자석 선형 동기 전동기(PMLSM)의 detent force는 입력전류가 가해지지 않은 상태에서의 영구자석과 철심간의 상호 작용에 의하여 발생된다. 이는 고정자에 관한 이동자의 위치 함수로서 표현 가능하다. 본 논문에서는 이동자의 위치에 따른 detent force를 측정하고, 이를 바탕으로 PMLSM 추력 리플의 원인이 되는 detent force를 저감하기 위한 보상법이 추가된 Field Oriented Control(FOC)을 제안하였다. 또한, 동일한 상황에서의 시뮬레이션 및 실험을 통해 제안된 제어법의 유효성을 입증하였다.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.225-229
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• 1998

If there is a mismatch between the controller programmed rotor time constant and the actual time constant of motor, the decoupling between the flux and torque is lost in an indirect rotor field oriented control. This paper presents a new estimation scheme for rotor time constant using artificial neural networks. The parameters of induction motor model organize 2 layer neural to be weight between neuron, which is proposed new in this paper. This method makes networks simple, so its brings not only the improvement in speed but simplification in calculation. Furthermore, it is possible to estimated rotor time constant real time through on-line learning without using off-line learning. The digital simulation and the experimental results to verify the effectiveness of the new method are described in this paper.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.265-269
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• 1994

The switching dead time avoiding a bridge leg short circuit in PWM voltage source inverter produces distortions of the controlling inverter output performance such as current waveform, voltage vector, and torque. In this paper, the influence of dead time is investigated. The on-line space voltage vector modulation method is used for current controller. It is possible to compensate dead time by space voltage vector modulation which generates additional pulse compensating voltage distortion caused by dead time. In addition, narrow pulse which is generally neglected can be compensated. All the algorithms, including field-oriented control are performed by one chip microprocessor 80C196MC and DSP TMS320C31. Experimental results probe that the proposed scheme provides a good inverter output performance.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.454-456
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• 1996

This paper deals with the comparison study of speed controller for torsional vibration suppression of 2-mass motor drive system. Firstly conventional methods suggested were classified systematically and the features of each method were also compared. Especially the speed controller based on Kalman filter and LQ state feedback was proposed and the response characteristics of it were compared with those of some other methods. Through various computer simulations and the experiments of real 22[KW] field oriented controlled AC motor drive system having 2-mas mechanical system, it was confirmed that the characteristic of proposed speed controller using Kalman filter and LQ is the best among them.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1195-1197
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• 2005

본 연구는 자계방향 기준 벡터제어 이론에 기초한 속도제어 시스템의 구성을 나타내었다. 제안한 속도제어 시스템은 전동기 모델이 자속기준 ${\gamma}-{\delta}$축 좌표변환 하여 선형제어 되고 관측기 이론에 기초하여 연산한 2차자속과 전류센스에서 검출한 전류값으로 속도제어 하는 알고리즘을 나타내었다. 그리고 제안한 방법이 자계방향 벡터제어 시스템의 실현에 유용성이 있음을 규명하였다.