• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.457-460
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• 2005

When a hearing aid' s user is listening through telephone or cellular phone, he/she usually suffers from severe electrical magnetic interference noise. It is because hearing aids amplify voice signal as well as background noise. A telecoil, an induction coil, is a possible solution for the problem. Because a telecoil has the characteristic of high pass filter, it has some problem of resulting increased high frequency noise. For solving this problem, we can use a capacitor connected with the telecoil in parallel. According to capacitance, receiving signal quality may change. In this paper, proper capacitor values for the best sound quality are investigated by experimental work.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.11
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• pp.875-881
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• 2003

The received signal of a mobile phone is normally sensed through two independent means which are the sound generation of a speaker and vibration generation of a vibration motor. As an improvement scheme to meet the consumer's demand on weight reduction and miniaturization of a mobile phone, the design and development of an integrated vibration and sound generating device are performed in this research. To this purpose, the optimal shapes of the voice coil. the permanent magnet and the vibration plate are designed, and the excitation force applied to the vibration system of the new device is estimated and verified through theoretical analyses, computer simulation, and experiments using an expanded model. In addition, vibration performance comparison of the device with the existing vibration motor is performed, and from the overall process, therefore, the method and procedure for the vibration performance analysis of the integrated vibration and sound generating device are established.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.5
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• pp.399-406
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• 2001

This paper presents a dynamic modeling and a sliding mode controller for the high-speed/high-accuracy position control system. The selected target system is the wire bonder assembly which is used in the semiconductor assembly process. This system is a reciprocating one around the pivot point that consists of VCM(voice coil motor) as an actuator and transducer horn as a bonding tool. For the modeling elements, the sys-tem is divided into electrical circuit, magnetic circuit and mechanical system. Each system is modeled using the bond graph method and united into the full system. Two major aims are considered in the design of the controller. The first one is that the horn must track the given reference trajectory. The second one is that the controller must be realizable by using the DSP board. Computer simulation and experimental results show that the designed sliding mode controller provides better performance than the PID controller.

• Journal of Mechanical Science and Technology
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• v.17 no.11
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• pp.1616-1627
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• 2003

This paper describes a mini linear optical pickup actuator. To reduce the size, inner yokes are designed to guide the mover and outer yokes of permanent magnets are removed. Magnetic circuit method is used to determine the thrust force. Virtual path method is proposed to analyze the open magnetic circuit analysis. The magnetic circuit of the proposed actuator can be a closed circuit due to the virtual path model of the outer magnetic flux. The validity of virtual path method is evaluated by comparing to the FEM analysis. Structural vibration is investigated using FEM and the design of the mover is modified to improve the vibration characteristic. Dynamic characteristic experiments shows that the performance of the proposed actuator is enough to be used as a coarse and fine seeking actuator simultaneously and the thrust force margin for loading a focusing actuator is guaranteed.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.8
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• pp.161-171
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• 2002

This paper presents a linear motor, which generates large thrust with a low operating rate. In industrial fields there is a need for actuators that work with a low duty cycle but generate large thrusts. An example of such a case is provided by the actuators for ejector mechanisms in electric injection molding machines. The ordinary LSM (linear synchronous motor) is unsuitable for this large-thrust and low-operating-rate usage, because of its large size and high cost. This paper contains experimental results on linear motors that can generate large thrusts for a short time, and which can be cheaply produced. The described linear motor could be contained space of $250mm \times250mm\times 250mm$ and generate a maximum thrust of about 20000 N at a current of 250 A.

• Journal of KSNVE
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• v.8 no.2
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• pp.274-282
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• 1998

A systematic procedure for designing a direct-radiator-type loudspeaker has been developed, based on the numerical vibro-acoustic analysis and the Taguchi method. The finite-element model of the speaker cone has been used to calculated the vibration response of the cone excited by the voice coil. The vibration displacement of the speaker cone has been converted into the vibration velocity and used as a boundary condition for the acoustic analysis. The acoustic frequency characteristics of the loudspeaker have been calculated by the boundary element method. The numerical results have been verified by the experiments carried out in an anechoic chamber. Some design parameters have been selected by using the Taguchi method, and the variations of the acoustic characteristics due to the changes of the parameter values have been examined using the numerical model.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.4
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• pp.473-479
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• 2008

With the advent of mobile phone, digital multimedia broadcasting(DMB) service is to be realized for multimedia data communication. For an acoustic part, a smaller and lighter microspeaker is also soon to be realized as an MP3 song player and a speakerphone. Sound quality in the microspeaker is becoming more important in mobile phones. It is evaluated by total harmonic distortion(THD). THD is the proportion of higher order frequencies output response to sinusoidal input signal. It is affected by uneven magnetic distribution and nonlinear response of diaphragm. In this paper, harmonic distortion is analyzed by considering magnetic and mechanical coupling effects. Simulated results of THD are compared with experimental data. Results show that THD in lower frequency range is higher due to high displace on voice coil and high mechanical response of high order frequency.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.568-574
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• 1998

A systematic procedure for designing a direct-radiator-type loudspeaker has been developed, based on a numerical vibro-acoustic analysis and the Taguchi method. The finite-element model of the speaker cone has been used to calculate the vibration response of the cone excited by the voice coil. The vibration response of the speaker cone has been used as a boundary condition for the acoustic analysis, and the acoustic frequency characteristics of the loudspeaker have been calculated by the boundary element method. The numerical model has been confirmed by comparing the numerical results with experimental ones obtained in an anechoic chamber. Some design parameters contributing dominantly to the acoustic characteristics have been selected by using the Taguchi method, and the variations of the acoustic characteristics due to the changes of the parameter values have been examined using the numerical model.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.3078-3080
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• 2005

본 논문에서는 AF 기능을 구현함에 있어서 2 백만 화소 카메라 모듈인 Sharp LZ0P3731의 기능, AF 모터 (VCM, Voice Coil Motor)에 작용하는 힘과 구동원리, 이를 구동하기 위한 H/W의 설계 특성, 및 DM270을 이용한 AF 제어 시 Focus Value의 특성 분석을 바탕으로 Focus Value 특성을 고려한 최적 AF 알고리즘을 개발하였다. 본 논문에서 제안한 최적 AF 알고리즘은 '최대의 Focus Value가 각 State의 Step Value 마다 각각 다른 위치에서 검출'되는 AF 모터 및 구동 H/W특성을 고려하여, 최적 AF 기능은 최대의 AF Value에 근접하는 Lens Position 제어가 가능하도록 하였다. 이를 검증하기 위한 윈도우용 S/W로 성능을 확인한 결과, 일반적인 AF 기능은 58 프레임으로 3.87초의 시간이 소요되는 반면, 제안한 AF 기능은 25 프레임으로 1.67초로 2배 이상의 빠른 AF 성능을 가졌다.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.10a
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• pp.150-153
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• 2006

Micro vibration isolation, typically originated from ground, is always a prime concern for the nano-measurement instruments such as Atomic Force Microscopes. A four mount active vibration isolation system is proposed in this paper. Modeling and control of such a four mount system as analyzed. Combined active-passive isolation principle is used for vibration isolation by mounting the instrument on a passively damped isolation system made of Elastomer along with the active stage in parallel that consists of very soft actuation system, the Voice Coil Motor. The active stage works in combination with the passive stage for working as a very low frequency vibration attenuator.