• Journal of Power Electronics
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• v.13 no.2
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• pp.264-274
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• 2013

A new sensorless position estimation method for switched reluctance motor (SRM) drives is presented in this paper. This method uses the change of the slope of the phase inductance to detect the aligned position. Since the aligned positions for successive electrical cycle of each phase are apart by a fixed mechanical angle $45^{\circ}$ in the case of 12/8 SRM, the speed of the machine can be calculated to estimate the rotor position. Since no prior knowledge of motor parameters is required, the method is easy for implementation without adding any additional hardware or memory. In order to verify the validity of this technique, effects such as changes in the advanced angle and phase lacking faults are examined. In addition, an inductance threshold based sensorless starting scheme is also proposed. Experimental results demonstrate the validity of the proposed method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.207-211
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• 2004

The performance of an inductive position sensor has approved by previous research papers. In this paper, magnetic circuit model of a ring-type multi-pole insuctive position sensor is described. The magnetic circuit model is required to design in ductive position sensor as well as draw a fault tolerance algorithm. Using the magnetic circuit theory, we derived the relationship between voltage applied and flux density in the normal air-gap. By idealizing the modulation/demodulation processes of signal processing circuit, sensor gain with respect to change of displacement is theoretically calculation using the magnetic circuit model, which validate the theoretical derivation.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.705-708
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• 2000

Switched Reluctance motors(SRM) attract much attention in motor because they are reliable and inexpensive. With advance in power electronics and high-speed processors the performance of SRM has been enhanced greatly. But they require rotor position information to operate, In many systems rotor position sensors are undesirable and have disadvantages. To overcome the disadvantages include by position sensors a number of sensorless methods for SRM's have been proposed by researchers. This paper describes a method for indirect sensing of rotor position in SRM's pulsewidth modulation voltage control. The method required no priori knowledge of motor parameters excepts for the number of stator and rotor poles. The detection method uses the change of the derivative of the phase current to detect the position.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.91-94
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• 2001

In this paper, we proposed localization method of mobile robot using color landmark mounted on ceiling. This work is composed 2 parts : landmark recognition part which finds the position of multiple landmarks in image and identifies them and absolute position estimation part which estimates the location and orientation of mobile robot in indoor environment. In landmark recognition part, mobile robot detects artificial color landmarks using simple histogram intersection method in rg color space which is insensitive to the change of illumination. Then absolute position estimation part calculates relative position of the mobile robot to the detected landmarks. For the verification of proposed algorithm, ceiling-orientated camera was installed on a mobile robot and performance of localization was examined by designed artificial color landmarks. As the result of test, mobile robot could achieve the reliable landmark detection and accurately estimate the position of mobile robot in indoor environment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12
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• pp.1115-1120
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• 2003

In this paper, we investigated the position dependent stress distribution of indium-tin-oxide (ITO) film on Polycarbonate (PC) substrate by external bending force. It was found that there are the maximum crack density at the center position and decreasing crack density as goes to the edge, In accordance with crack distribution, it was observed that the change of electrical resistivity of ITO islands is maximum at the center and decrease as goes to the edge. From the result that crack density is increasing at same island position as face plate distance (L) decreases, it is evident that the more stress is imposed on same island position as L decreases.

• The Journal of Korean Physical Therapy
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• v.12 no.1
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• pp.57-63
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• 2000

The purpose of this study was to evaluate of balance performance and to examine the relationship between balance performance and feet position, platform speed. Twenty two subjects(men 8, women 14, mean age 24.45years) performed nine balance test with eyes closed for 25seconds:3 feet position(feet together, feet 12cm in apart, feet 24cm in apart) and 3 platform speed$(100\%,\;70\%,\;40\%)$. The results were as fellows: 1. There are significant difference between center of balance and feet position(p<0.05). 2. There are no significant difference between center of balance and plaform speed(p<0.05). 3. There are significant difference between sway index and feet position(p<0.05). 4. There are significant difference between away index and plaform speed(p<0.05).

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.2
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• pp.53-57
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• 2017

This papers propose a Hall-effect sensors position error compensation method in a sunroof system using a BLDC motor with a low-cost MCU. If the BLDC motor is controlled with this wrong position, the torque ripple and operating current can be increased and the average torque also decreases. Generally, sunroof system has characteristics that operate at constant load for several seconds. It is possible to find the minimum operating current value while changing the position of the Hall-effect sensor during the sunroof operation by using these characteristics. Therefore, propose a method to change the Hall-effect sensor position and find the minimum current value. The validity of the proposed algorithm is verified through experiments.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.64-66
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• 1999

Switched reluctance motor(SRM) has the advantages of simple structure, low rotor inertia and high efficiency. However, position sensor is essential in SRM in order to synchronize the phase excitation to the rotor position. The position sensors increase the cost of drive system and tend to reduce system reliability. This paper investigates the speed control of sensorless SRM in which the phase current and change rate are utilized in position decision, and the period of dwell angle is variable by compensating the rotor angle. The proposed system consists of position decision, phase locked loop controller, switching angle controller and inverter. The performances in the proposed system are verified through experiments.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.684-686
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• 2000

Switched reluctance motor(SRM) has the advantages of simple structure, low rotor inertia. and high efficiency. However position sensor is essential in SRM in order to synchronize the phase excitation to the rotor position. The position sensors increase the cost of drive system and tend to reduce system reliability. This paper investigates the speed control of sensorless SRM in which the phase current and change rate are utilized in position decision, and the period of dwell angle is variable by compensating the rotor angle for speed control. The proposed system consists of position decision. phase locked loop controller, switching angle controller and inverter. The performances in the proposed system are verified through the experiment.

• Clinics in Shoulder and Elbow
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• v.5 no.2
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• pp.118-123
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• 2002

Purpose: The purpose was to identify the effectiveness of beach-chair position in the arthroscopic Bankart repair over conventional lateral decubitus position with distal traction. Materials & Methods: 36 arthroscopic Bankart repair through July 2000 to July 2001 was done under beach chair position. All cases were shoulder instability. Male patients were 6 and female were 4 with average age of 25 years. Arthroscopic suture anchor was used in 24 cases and average number was 3. Results: Interscalene block was tried in 29 patients and 1 case was changed to general anesthesia. Arthroscopic examination to identify Bankart lesion and associated pathology was done without difficulty Bankart lesions were easily reduced to anatomic position and placed suture anchor and hooking approprately. After the arthroscopic examination,3 cases were converted to open procedure without any positional change. Conclusion: Under interscalene block, the preparation was more simple and the patient could watch arthroscopic procedure with confidence. There was no hindrance in arthroscopic examination and arthroscopic repair could be dont: in more anatomic position. It can be easily changed to open repair if it needed