• 한국공작기계학회논문집
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• 제15권1호
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• pp.82-87
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• 2006

The cutting tests of aluminum alloy with heat treatmented various hardnesses after rheo-fonning were carried out using CNC milling machine. The surface roughness(Ra, Rmax) of cut surface and cutting forces are measured at various cutting conditions such as low spindle speed, feed speed and hardness. In the CNC end-milling, the surface roughness increases as feed speed increases and decreases as spindle speed increases. However, the bulit-up edge has occurred on in case of low hardness and low feed speed. In experimental conditions, as the hardness of aluminum alloy increases, the surface roughness(Ra, Rmax) decreases

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.576-578
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• 1994

In this. paper, a new technique to estimate both the instantaneous speed and disturbance load torque using a low precision shaft encoder in very low speed range is proposed. To detect the instantaneous speed and disturbance load torque, the Kalman filter which is an optimal full order estimator is used. Experimental results conform the validity of the proposed estimation technique. The effects of parameter variations are discussed, and it is verified that the system is robust to the modeling error.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.201-208
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• 2004

In this study a general Galerkin FE lubrication analysis method was utilized to analyze the complex lubrication performance of a spiral groove seal having an additional inner circular groove, which was designed for a chemical process mixer operating at a low speed of the maximum 500 rpm. Equilibrium seal clearance analyses under varying outer pressure revealed that the seal maintains a certain levitation seal clearance under the outer pressure of more than about 1.5 bar, regardless of a rotating speed. Also, under the normal outer pressure of 11 bar, the axial stiffness of the seal was predicted to have a high value of more than 7.0e+07 N/m, regardless of a rotating speed and thereby, the seal is expected to maintain a stable thickness of lubrication film under a certain external excitation acting.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.287-291
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• 1992

Recently, electronic engine control system is used in many automotives for high efficiency and low pollution. In order to perform these requirements, fuel injection control, spark timing control, knock control, exhaust gas recirculation control and idle speed control should be implemented. In this paper, idle speed control system using microcontroller is developed, which is compact in hardware, but powerful in software performing efficient control and various compensations for engine condition and environments. If idle speed is low engine operation is not smooth, reversely if high, fuel consumption is increased. Therefore idle speed must be maintained as low as possible within the scope that ensures smooth operation of engine. Also, an engine signal simulator, which generates various signals from engine, is realized for test facility.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.706-708
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• 1998

Recently, it was very difficult for hydraulic governor to regulate the speed of high power engine with long stroke at low speed and low load, because of the jiggling phenomena by rough fluctuation of rotating torque and the hunting phenomena by long dead time occurred in fuel combustion process in the engine cylinder. In this paper, the influence of engine dead time is investigated by Nickels chart, and hybrid controller selected advantages of PID and fuzzy logic controller is provided to improve the performance of speed control of a low speed and long stroke diesel engine.

• 전자공학회논문지B
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• 제31B권6호
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• pp.53-62
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• 1994

In this paper, a fuzzy logic-based idle speed controller is designed for automotive engine with a purpose of high efficiency and low pollution. When the idle speed is low engine operation is not smooth, otherwise fuel consumption is incresed. Therefore the idle speed must be maintained as low as possible within the scope that ensures smooth operation of engine. By simulation, we show that the idle speed controller has generated a proper control signal as engine condition or enviornment varies, and also operated well for unexpected cases. Also, an engine simulator, which is used as a basic tool for controller design, is developed and utilized for reduction of development time and cost.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1003-1005
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• 2000

The switched reluctance drive provides a good adjustable steed characteristics like a D.C series motor. However, because of the torque production mechanism, it also has some disadvantage such as higher torque ripple and fluctuation in speed. To reduce torque ripple and to control speed precisely at low condition current level technique is adopted. The SRM drive with current control of invariable frequency and phase swichting control has good speed regulation characteristics. Digital control system with an 80c196kc micro-controller is used to realize this drive system. Test results show that the control system has the goof ability to achive precise speed control at low speed.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1582-1591
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• 2014

This paper presents a hybrid sensorless control for an interior permanent magnet synchronous motor (IPMSM) for zero-, low-, and high-speed regions. Many sensorless control methods such as an observer-based estimator have been introduced. However, most of the observer-based estimators have a disadvantage at start-up and in the low-speed region. To solve this problem, a simple strategy of using a hybrid system is proposed by integrating a high-frequency (HF) signal injection method and a full-order flux observer. In addition, an HF signal injection method with only a low pass filter (LPF) is proposed to simplify the hybrid system. The hybrid system achieves high-performance drive throughout the entire speed range. The effectiveness of the proposed hybrid technique is verified by experiments using an 11-kW IPMSM drive system.

• 한국산학기술학회논문지
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• 제13권11호
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• pp.5416-5426
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• 2012

본 논문에서는 유도전동기의 저속운전영역에서 고속운전영역에 이르기까지 모든 영역에 걸친 안정된 속도제어를 목적으로 전압 전류 모델 합성 자속 추정기를 통해 저속영역에서와 고속영역에서 각각 다른 모델에 의한 자속을 추정하고 이로부터 자속각을 추정하는 알고리즘을 사용한다. 특히 저속영역에서 부하가변시의 전류의 변화와 자속의 변화를 실시간으로 추정하여 저속영역에서의 제어특성을 향상시켜 부하 가변 시에도 전 영역에서 보다 안정된 비례적분 전류 제어기, 비례적분자속 제어기에 의한 시뮬레이션 및 실험을 실시한 결과 우수한 속도제어특성을 얻을 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권4호
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• pp.503-510
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• 2003

A new method of induction motor drive, which requires neither shaft encoder nor speed estimator, is presented. The proposed scheme is based on decreasing current gap between a numerical model and an actual motor. By supplying the identical instantaneous voltage to both model and motor in the direction of reducing the current difference. the rotor approaches to the model speed. that is. reference value. The indirect field orientation algorithm is employed for tracking the model currents. The performance of induction motor drives without speed sensor is generally characteristic of poorness at very low speed. However, in this system, it is possible to obtain good speed response in the extreme low speed range.