• Journal of KSNVE
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• v.9 no.5
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• pp.922-927
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• 1999

The objective of this paper is to obtain the contribution of each source to the spectrum of pressure, when there are multiple incoherent sources in near-field acoustic holography. For this objective, we have to obtain signals very coherent to the input signals of the sources. To obtain the very coherent signals, many people have measured pressure signals in the vincinity of the sources. However, it is sometimes difficult to locate microphones near to the sources so that the signals are very coherent to the input signals. This paper proposed a method to obtain the very coherent signals by near-field acoustic holography. Therefore, the proposed method does not require the measurement of pressure near to each source. Simulation results for two incoherent monopole sources showed the possibility of the proposed method.

• Tribology and Lubricants
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• v.23 no.5
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• pp.240-247
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• 2007

The design process of the dental handpiece is described. The parameters of the high speed air turbine are estimated. The effect of supply hole on the stiffuess and damping of the air bearing for handpiece is studied numerically. The Reynolds equation is solved by using the divergence formulation and the perturbation method. The test rig is built and the test procedure is developed for the turbine rotational speed measurement by using Fourier transform of noise generated by the turbine during steady operation.

• Science of Emotion and Sensibility
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• v.1 no.2
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• pp.133-147
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• 1998

이 글은 영구의 자동차내부 소음연구와 보버르트(Bobbert)의 첫 번재 독일어로 쓰인 연구를 다루고 있다. 승용차내부소음은 높은 적외파음향(infra sound)으로 특징지어 진다. 그런 까닭으로 그러한 종류의 소음을 A-평가계측(A-rated measurement)으로 그 영향을 파알하는 것은 한계가 있다. 자동차음향공학은 특히 인공청각(artificial head)기술의 발전, 소리의 합성적 제조 및 다양한 자동차 내부 음색(timbre)에 대한 일본연구가들 (하쉬모토, 쿠와노, 남바)에 의해 상당산 성취를 경험하였다. 위의 연구들은 무엇보다도 의미분별기법(Semantic Differentials)과 다차원측정방법(Multidimen-sional Scaling)을 사용하고 있다. 그러한 기법의 사용은 심리측정방법을 심리음향학(Psycho-acoustics), 특히 츠뷔커학파(Zwicker school)의 심리음향학 방법론과 결합한 것으로 볼 수 있다.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.3
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• pp.113-121
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• 2014

This paper presents a optimization design of 10[W] single phase BLDC motor applied Notch shape. Cogging Torque causes noise, vibration and torque ripple so notched stator is proposed in this paper. Firstly, a single phase BLDC motor needs applying aymmetric air-gap shape because this type motor cannot help having dead-point which is zero torque position. However, using asymmetric air-gap structure causes cogging torque increase. Therefore, this paper proposes the notch shape structure. Notch shape structure has some advantages; low cost, easy to apply. There are 4 optimal factors selected in optimization process, which are position and size of notches. Through building a prototype, the result of FE analysis and the experimental measurement value are compared each other and then vailidity and utility of simulation will be verified.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.242-243
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• 2015

Fault detection using optical emission spectra with modified K-means cluster analysis and principal component anal ysis are demonstrated for inductive coupl ed pl asma cl eaning processes. The optical emission spectra from optical emission spectroscopy (OES) are used for measurement. Furthermore, Principal component analysis and K-means cluster analysis algorithm is modified and applied to real-time detection and sensitivity enhancement for fluorocarbon cleaning processes. The proposed techniques show clear improvement of sensitivity and significant noise reduction when they are compared with single wavelength signals measured by OES. These techniques are expected to be applied to various plasma monitoring applications including fault detections as well as chamber cleaning endpoint detection.

• Journal of the Korea Institute of Building Construction
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• v.11 no.6
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• pp.618-626
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• 2011

The characteristics of construction work cause excessive strain on specific body parts of the construction craft workers. However, there are few tools to mane an accurate measurement of the load on the musculoskeletal system, and the musculoskeletal disorders (MSDs) experienced by the workers have not been properly understood. So, there is an urgent need for development of a tool to measure the load on the musculoskeletal system. Therefore, this research aims to develop a musculoskeletal load measuring device for construction workers. In order to eliminate the noise and errors, an accelerometer, gyro sensors and the Kalman Filter are used in the device developed in this research.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.595-597
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• 1998

This paper deals with an algebraic compensator design for dynamic systems using a novel BPF transformation method. To obtain an algebraic compensator for the system, block pulse function's differential operation is used. Compare to unalgebraic compensator, proposed algebraic compensator is less sensitive to the measurement noise.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.280-282
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• 1994

This paper proposes sliding mode state for robust speed control of induction motor. Sliding mode state observer is robust for measurement noise, modeling-error and load disturbance. The pole of sliding mode state observer can be placed at (0,0) in Z-plane for fast response. This method is, namely, deadbeat control. Sliding mode state observer output is discontinuous on a switching hyperplance, that causes harmful effects such as current harmonics and speed oscillation. In this paper, also the reducing method of the chattering of sliding mode state observer output is proposed. The proposed system is digitally implemented with TMS320C31.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.544-550
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• 2008

In this paper, an efficient positioning algorithm is proposed for a local positioning system using ultrasound and RF in WSN. The proposed positioning algorithm is the modified Savarese method where measurement noise characteristics are included as a weighting. Furthermore the ill-conditioned and the singularity problem occurred when all beacons are installed at the same height are removed. And the method is applicable to 2D positioning with 2 beacons only. The experiments with implemented system show the accurate seamless positioning less than 2cm error both static and dynamic experiments while the original Savarese method can not provide positions.

• Journal of Power System Engineering
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• v.1 no.1
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• pp.144-153
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• 1997

The magnetic levitation system is utilized in the magnetic bearing of high-speed rotor because of little friction, no lubrication, no noise and so on. The magnetic levitation system need the feedback controller for the stabilization of system, and gap sensors are generally used to measure the gap. The use of gap sensors brings out the increase of the number of troublesome, and the decrease of the control performance because of the dislocation between the measurement point and the control point. This paper presents the design of the gap estimation circuit for the sensorless method proposed by authors in the magnetic levitation system. We made the gap estimation circuit which was composed of both the superposition circuit and the measuring circuit. And we investigated the validity of the usefulness of the proposed sensorless method in the magnetic levitation system through results of actual experiment.