• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.305-344
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• 2008

This paper presents the active control of flexible beam vibration. The beam was excited by a steady-state point force by mini shaker and the control was performed by mini shaker. To perform active control, least-mean-square (LMS) algorithm was used because it can easily obtain the complex transfer function in real-time. So an adaptive controller based on Filtered-X LMS algorithm was used and the controller was defined by minimizing the square of the response at a location of error sensor. In order to fine out performance tendency, input amplitude was changed in several cases and active vibration control was performed.

• 대한의용생체공학회:의공학회지
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• 제17권2호
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• pp.201-208
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• 1996

We have been studying an implant type EMG-controlled electrolarynx. First of all, we propose the sternohyoid muscle(SH) as a control source of the electrolarynx. The purpose of this study is to investigate the possibility that subjects control voluntarily the constriction of their SH, and produce the control signals of electrolarynx. For this pwnan, we carried out four experiments regarding the control of the electrolarynx. At the results, we found that subjects can control the start/stop of constriction and the amplitude of EMG of their SH. Also, we ascertained the possibility that the start/stop of contraction of SH controls OW/OFF of sound source of the electrolarynx and the amplitude of UG of SH controls the pitch frequency of the electrolarynx.

• The Journal of the Acoustical Society of Korea
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• 제26권1E호
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• pp.27-32
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• 2007

Hydraulic actuator and electro-magnetic liner actuator have been used as typical active vibration control methods. However these methods have many kinds of disadvantages such as causing space limit, difficult maintenance, complicate structures, etc. The purpose of this paper was to study on the possibility of active vibration control using piezoelectric transducer. Piezoelectric transducer generated a vibration and GIC (General Impedance Converter) amplifier was adopted to give adjustable vibration signal to transducer and high amplitude of vibration. Resonance frequency of piezoelectric transducer was controlled by GIC amplifier and higher amplitude of vibration was achieved. Finally active vibration control using piezoelectric transducer was performed.

• Journal of Acupuncture Research
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• 제29권6호
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• pp.57-71
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• 2012

Objectives : The purpose of this study is to find the effects of Sa-Am stomach tonifying acupuncture on radial pulse through the parameters difference. Methods : Forty healthy subjects participated in this study, acupuncture group and control group were divided. Radial pulse were measured using 3 dimensional pulse imaging system(DMP-3000). 19 parameters that significantly changed were selected after comparing between acupuncture group and control group. Then, 19 parameters were analyzed before, immediately after, 30 minutes after and 60 minutes after acupuncture in acupucture group. Results : 1. Heart rate, pulse period, T/T1, T2/T, T4/T, T5/T, T-T4, (T-T4)/T and T4/(T-T4) significantly changed after acupuncture. 2. H1 Amplitude, H2 Amplitude, H4 Amplitude and H5 Amplitude significantly changed after acupuncture. 3. Area of Pulse Wave, Systolic Pulse Area, Diastolic Pulse Area and Area of W significantly changed after acupuncture. 4. AIx/HR significantly changed after acupuncture. Conclusion : Stomach Tonifying Acupuncture exerts an influence on radial pulse parameters. Further radial pulse change study on various acupuncture treatment is required.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2008년도 춘계 학술발표회 논문집
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• pp.139-144
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• 2008

본 논문은 건물의 형태와 동적특성을 변화시키지 않고 건물에 부가질량을 설치하여 건물의 진동을 제어하는 방법중 수동형 제진장치인 TLD(tuned liquid damper)와 MTLD(multiple tuned liquid damper)의 진동응답을 감소시키기 위해 진동대를 이용한 성능실험을 실시하였다. 따라서 기존의 형태별(원형, 직사각형) TLD 실험의 실험 데이터를 가지고 가진 진폭(1mm, 3mm, 5mm, 10mm, 20mm) 의 변화에 따른 고유진동수(0.44Hz, 0.55Hz)에 대한 MTLD의 형태별 실험을 통하여 TLD와 MTLD의 진동감소효과에 대한 성능실험을 비교 분석 하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.591-595
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• 2000

Sound absorbing characteristics of poroelastic materials is known to be greatly affected by high intensity acoustic waves. However, this effect has not been considered yet. In this study, the extended semilinear model based on Biot's theory for the porous materials and the characteristics of nonlinear waves in poroelastic sound absorbing materials were introduced. The expressions for the finite-amplitude acoustic plane waves were presented. By combining each nonlinear wave with appropriate matching conditions, we could investigate the effects of finite-amplitude acoustic waves on absorption characteristics of poroelastic materials. In the most ideal case considered in this paper, the absorption coefficient was found to become larger than that of linear incident waves. It was shown that the absorption coefficient became greater especially as frequency goes higher and as distance from the source goes larger. These phenomena may be inferred to result from 'dissipation effects due to nonlinearity'. This finding may have important implications for high intensity noise control.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.300-303
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• 2002

With increase of servo motor In industrial and home application, a number of papers related to PMSM control have been researched. Among them, sensorless control schemes are especially concerned in the view point of its cost reduction. In the conventional approach, a rotor position is generally estimated by the integration of estimated rotor speed. In this method, because of their tight relationship between the amplitude of back-emf and rotor position. it is somewhat difficult to find two parameters at the same time. To solve this problem, a novel sensorless control scheme is proposed. It utilizes a back-emf normalization, so it does not requires the variables related with the amplitude of back-emf. The validity of the proposed control scheme was verified through experimental results.

• Structural Engineering and Mechanics
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• 제87권2호
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• pp.117-127
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• 2023

To efficiently attenuate seismic responses of a structure, a novel pneumatic-driven active dynamic vibration absorber (PD-ADVA) is proposed in this study. PD-ADVA aims to realize closed-loop control using a simple and intuitive control algorithm, which takes the structure velocity response as the input signal and then outputs an inverse control force to primary structure. The corresponding active control theory and phase control mechanism of the system are studied by numerical and theoretical methods, the system's control performance and amplitude-frequency characteristics under seismic excitations are explored. The capability of the proposed active control system to cope with frequency-varying random excitation is evaluated by comparing with the optimum tuning TMD. The analysis results show that the control algorithm of PD-ADVA ensures the control force always output to the structure in the opposite direction of the velocity response, indicating that the presented system does not produce a negative effect. The phase difference between the response of uncontrolled and controlled structures is zero, while the phase difference between the control force and the harmonic excitation is π, the theoretical and numerical results demonstrate that PD-ADVA always generates beneficial control effects. The PD-ADVA can effectively mitigate the structural seismic responses, and its control performance is insensitive to amplitude. Compared with the optimum tuning TMD, PD-ADVA has better control performance and higher system stability, and will not have negative effects under seismic wave excitations.

• Journal of Astronomy and Space Sciences
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• 제28권4호
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• pp.261-265
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• 2011

We investigate the sunspot area data spanning from solar cycles 1 (March 1755) to 23 (December 2010) in time domain. For this purpose, we employ the Hilbert transform analysis method, which is used in the field of information theory. One of the most important advantages of this method is that it enables the simultaneous study of associations between the amplitude and the phase in various timescales. In this pilot study, we adopt the alternating sunspot area as a function of time, known as Bracewell transformation. We first calculate the instantaneous amplitude and the instantaneous phase. As a result, we confirm a ~22-year periodic behavior in the instantaneous amplitude. We also find that a behavior of the instantaneous amplitude with longer periodicities than the ~22-year periodicity can also be seen, though it is not as straightforward as the obvious ~22-year periodic behavior revealed by the method currently proposed. In addition to these, we note that the phase difference apparently correlates with the instantaneous amplitude. On the other hand, however, we cannot see any obvious association of the instantaneous frequency and the instantaneous amplitude. We conclude by briefly discussing the current status of development of an algorithm for the solar activity forecast based on the method presented, as this work is a part of that larger project.

• 한국산학기술학회논문지
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• 제8권3호
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• pp.522-527
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• 2007

본 논문에서는 다중부호 신호(multi-code signal)를 정진폭으로 전송하는 정진폭 다중부호 이진직교 변조방식(constant-amplitude multicode-biorthogonal modulation)에서 사용될 수 있는 오류제어 부호를 제안한다. 격자부호를 사용하여 시스템의 비트 오율 성능을 높이는 방식이 정진폭 다중부호 이진직교 변조방식에 적합함을 보인다. 정진폭 다중부호 이진직교 변조방식에서는 정진폭을 유지하기 위해 세로축의 패리티 비트를 사용하여 신호를 부호화 하게 된다. 제안된 시스템에서는 정진폭을 유지하기 위해 사용되는 세로축의 패리티 비트에 추가적으로 부호화를 수행하여 가로축의 패리티 비트를 부가하되 격자구조가 되도록 하여 비트오율 성능의 개선을 최대화 한다. 제안된 시스템은 시스템 복잡도의 증가가 거의 없으며 복호기도 매우 간단하게 구현될 수 있다. 실험결과에 의하면 제안된 시스템은 격자구조를 사용하지 않은 시스템에 비해 현격한 성능의 개선이 있음을 알 수 있다.