• 센서학회지
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• 제21권1호
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• pp.7-12
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• 2012

In this paper, we propose a 4-transistor active pixel sensor(APS) with a novel correlated double sampling(CDS) circuit for the purpose of extending dynamic range. Dual sampling techniques can overcome low-sensitivity and temporal disparity problems at low illumination. To accomplish this, two images are obtained at the same time using different sensitivities. The novel CDS circuit proposed in this paper contains MOS switches that make it possible for the capacitance of a conventional CDS circuit to function as a charge pump, so that the proposed APS exhibits an extended dynamic range as well as reduced noise. The designed circuit was fabricated by using $0.35{\mu}m$ 2-poly 4-metal standard CMOS technology and its characteristics have been evaluated.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.672-672
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• 2011

This study describes the comparison of noise suppression performances at different locations of two error microphones in active noise control (ANC) for outdoor applications. For this study, 12 different locations were predefined to decide best locations for error sensors in terms of suppressing noise. As shown in Fig. 1, the ANC system with one primary loudspeaker, two secondary loudspeakers and two error microphones is operated by a filtered-x LMS (FXLMS) algorithm which is implemented in a TI 6713 DSP board and Realsys 4713 AD/DA Extension board. The noise for the primary source is a typical road noise measured at a highway roadside. The lengths of adaptive filters of W1 and W2 are varied from 32 to 128 respectively. An intensive computer simulation was accomplished before outdoor ANC experiments. It is expected from the simulation results that the ANC performances are very much dependent upon the locations of the two error microphones.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.153-156
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• 2006

The vibration isolation system is a system that attenuates the vibration transmitted from surroundings by using external energy supply like electricity and feedback and/or feedforward functions. Such a system needs stiff structure to make precise positioning without ripple within a certain bandwidth. So, a horizontal and rotary arrangement of the actuation module is suggested by using lever linkage. Modeling and kinematic formulation are completed and system identification is accomplished to tune the design variables accurately. The vibration isolation control is performed by mu-synthesis with the uncertainties in design variables. Low frequency signal enhancement circuit and saturation proof integration algorithm are devised to use seismic sensors for displacement control. This overall system shows good disturbance rejection performance.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.208-209
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• 2003

We have developed a practical Brillouin active fiber ring sensor of length less than 20m, by employing an optical amplifier to compensate for most of the connection losses in the ring. The loss reduction brings the standard Brillouin threshold from 21 down to 0-0.1 through the enhancement of the finesse of the ring. However, in the course of our experiments, some level of temporal instability and chaotic behavior in the backscattered Stokes intensity and also in its spectral line shift were consistently observed. (omitted)

• 로봇학회논문지
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• 제2권3호
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• pp.221-226
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• 2007

A robust position-sensing system is proposed in this paper for ubiquitous mobile robots which move indoor as well as outdoor. The Differential GPS (DGPS) which has position estimation error of less than 5 m is a general solution when the mobile robots are moving outdoor, while an active beacon system (ABS) with embedded ultrasonic sensors is selected as an indoor positioning system. The switching from the outdoor to indoor or vice versa causes unstable measurements on account of the reference and algorithm changes. To minimize the switching time in the position estimation and to stabilize the measurement, a robust position-sensing system is proposed. In the system, to minimize the switching delay, the door positions are stored and updated in a database. The reliability and accuracy of the robust positioning system based on DGPS and ABS are verified through the real experiments using a mobile robot prepared for this research and demonstrated.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.58-67
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• 2006

In this paper, fuzzy logic based active ventilation system with security function is proposed and implemented. We can easily experience the situation that inner air is so hot to get start immediately after parking at summer day. Hot temperature is enough to explode a gas lighter or to suffocate a little chid. Proposed system has 1 blower and 2 axial fans to ventilate inner air. Based on the fuzzy logic, speed and direction of each fan are controlled. In addition to controlling fans, controller put down windows and adjust the periods of open time. In order to prevent the theft and security problems, IR sensors are used to detect objects. On detecting objects, controller put up windows. Experimental result shows that implemented system can be effectively ventilate inner air and reduce temperature. Proposed system can be applicable to commercial automobiles.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.533-534
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• 2013

This paper is concerned with the active vibration control of rectangular plate equipped with MFC actuators. To this end, the dynamic model of the rectangular plate bonded with MFC sensors and actuators was derived by means of the Rayleigh-Ritz method. The MFC actuator and sensor were modeled based on the pin-force assumption. The theoretical model was then validated experimentally. The multiinput and multi-output (MIMO) Positive Position Feedback (PPF) controller was designed based on the natural mode shapes and implemented using dSpace system and Simulink. The proposed control algorithm was applied to the cantilever plate having two MFC wafers having both sensor and actuator. Numerical and experimental investigations were carried out. Both theoretical and experimental result shows that the proposed control algorithm can effectively suppress vibrations of cantilever plate.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1993년도 추계학술대회논문집; 반도아카데미, 26 Nov. 1993
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• pp.5-18
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• 1993

This paper reports the recent trends in active vibration control in Japan, especially, based on papers selected in the Proceedings of First International Conference on Motion and Vibration Control (1st MOVIC) held at Yokohama, Japan on Sept.7-11, 1992. Firstly, it classifiers vibration control methods and vibration controllers, especially active dynamic absorbers which are widely used in mechanical and civil engineering. Secondly, it covers basic problems in the control of vibration of flexible structures such as formulating a reduced-order model required for designing vibration controller, proper arranging of sensors and actuators, and preventing of spillover instability. Finally, the practical use of control theories such as LQ control theory, $H^{\infty}$ control theory, neural network theory, and other topics are discussed..

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.310-313
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• 2005

This paper is concerned with the active vibration control of beam equipped with piezoceramic sensors and actuators. The single-input and single-output positive position feedback controller is considered as an active vibration controller for the beam. The proposed single-input and single-output positive position feedback controller can cope with many modes of interest by summing each positive position feedback controller designed for each mode. In this paper, theoretical formulation is first explained in detail. We discuss how to design the single-input and single-output positive position feedback controller for a target structure by considering Euler-Bemoulli beam. It is found that the theories developed in this study are capable of predicting the control system characteristics and its performance.

• 센서학회지
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• 제27권6호
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• pp.374-379
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• 2018

The piezocomposite transducer is widely used because it is highly efficient in transforming electric energy into mechanical energy, and its frequency range is broader than that of other types of ultrasound transducers. A general piezocomposite transducer is composed of an acoustic lens, impedance matching layers, piezoelectric materials, and backing layers. When an input voltage is applied to a piezoelectric material as an active material, it generates sound waves while vibrating. At that time, an impedance matching layer helps the sound waves to propagate forward while reducing the impedance mismatch that may occur at the interface between the active material and its front material. The impedance mismatch has a negative effect on the signal of an ultrasound transducer; thus, it is important to design a matching layer to overcome the issue. In this study, an optimized feature of a matching layer with gradient properties is studied. An objective function is defined to minimize both the average and the deviation of the reflection coefficients that are functions of the frequencies. As a result, an improvement in the signal characteristics with respect to the sensitivity and bandwidth is reported.