• Interaction and multiscale mechanics
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• 제2권2호
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• pp.189-207
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• 2009

Dynamics of the electric system for the toroidal drive under mechanical disturbance is presented. Using the method of perturbation, free vibrations of the electric system under mechanical disturbance are studied. The forced responses of the electric system to voltage excitation under mechanical disturbance are also presented. We show that as the time grows, the resonance vibration caused by voltage excitation still exists and the vibrations caused by mechanical disturbance are enlarged. The coupled resonance vibration caused by mechanical disturbance and voltage excitation is discussed. The conditions of the occurrence of coupled resonance are studied.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.275-278
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• 2001

Research on the forced vibration control of a flexible GFR composite beam using $\mu$-synthesis is performed on this paper. Modal analysis method and modal coordinates are introduced to obtain the state equations of the structural system. Using these equations, Robust control algorithm using $\mu$-synthesis is adopted to suppress the forced vibration of a flexible beam since the designed controller can considered plant uncertainty and external disturbance. Constant disturbance which is generated by shaking the flexible beam as I's natural frequency is effectively rejected by a PZT actuator. Simulations and experiments are carried out with the designed controller and effectiveness of forced vibration suppression strategy is verified by results.

• 대한치과교정학회지
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• 제35권3호
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• pp.227-237
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• 2005

하악 제1대구치의 맹출 장애는 매우 드문 편으로 맹출로에 물리적인 장애가 있거나 맹출 과정의 결함으로 인해 생긴다. 하악 제1대구치의 맹출 장애가 있으면 그 원인을 살펴 정확한 치료계획을 세워야 하는데 무엇보다도 조기진단과 조기 치료가 중요하다 일차미맹출(primary retention)된 하악 제1대구치를 치개 절개와 forced eruption을 통해 치료하여 치료결과가 양호하고 성공적으로 유지된 증례를 살펴보고자 한다.

• 제어로봇시스템학회논문지
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• 제12권7호
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• pp.637-643
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• 2006

Generally, the tracking performance of optical disk drive(ODD) system can be improved using a disturbance observer(DOB). However, a DOB is not easily applied in an ODD system because an additional microprocessor, such as a digital signal processor(DSP), is needed. This paper shows how a DOB system can be replaced by the error-based modified disturbance observer(EM-DOB) when two mathematical conditions are satisfied. Due to the simplified structure of EM-DOB, the algorithm is easily implemented as an analog circuit, which is suitable for the ODD servo system. Additionally, in these algorithms, disturbances rejection performances can be tuned as Q filter parameters. Similar to a DOB system, three design guidelines of a Q filter can be applied. Experimental results of DOB and EM-DOB are evaluated under forced disturbances.

• Journal of Ecology and Environment
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• 제30권1호
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• pp.69-73
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• 2007

The sources and the frequency of disturbances and the responses of shorebirds to disturbances were studied at four roosting sites on Ganghwa Island and Yeongjong Island. The mean frequency of disturbance to roosting shorebirds was 2.7 per hour. Human activities contributed to the disturbance in 65% of all cases. Disturbance frequencies in saltpans were higher than those in the upper tidal zone, fishponds and salt marshes. Response patterns of shorebirds to disturbances were associated with the source of the disturbance. Disturbance caused shorebirds to change their behavior and to reduce roosting time at their roosting sites. Four patterns of responses by roosting shorebirds to disturbance were found, including: (1) leaving the roosts, (2) changing their location within the site, (3) leaving and returning, and (4) remaining in place. In the latter three response patterns, the birds tended to remain in their initial roosting sites, in contrast with the leaving pattern, which involved departing from the roosting area. Factors affecting these response patterns were time from high tide and time of day. When the time from high tide was greater, and the time of day was later, more birds stayed at the roost. The absence of sufficient alternative roosts in the study areas forced the birds to choose between tolerating the current disturbance, or moving to distant roosts.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.175-178
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• 1991

The drive system of servo motor is requested to have robustness of disturbance and parameter variation. However, the dynamics of PMSM drive change significantly by forced disturbance and parameter variation. Moreover, the state error caused by them should be suppressed completely and rapidly. In this paper, the vector-control system of PMSM using dual adaptive control loop is investigated. In the proposed system, linear adaptive control loop rapidly recovers the state error caused by both disturbance and parameter variation. In the dual adaptive control loop, the inner loop reduces the system sensitivity of parameter variation and disturbance, and the outer loop suppresses the state error caused by them completely. The proposed servo system is verified through a computer simulations and experimental results.

• 대한기계학회논문집A
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• 제20권2호
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• pp.540-552
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• 1996

In this paper, a compensation method of disturbance using a disturbance observer is proposed for a force control of a pneumatic robot manipulator. The generated torque by a pneumatic actuator can be estimated based on the pressure signals. The inner torque control system is constructed by feeding back the generated torque to improve the dynamic characteristics of the actuator. In order to reduce the influence of disturbances comprising friction torque, parameter variations of plant and environment and so on, the reaction torque control system is constructed with a disturbance observer which estimates the disturbances based on the reference input to the inner torque control system and the reaction torque sensed with a forced sensor. From some simulations and experiments, it is confirmed that the proposed control system is effective to improve the robustness for the friction torque and the parameter change of object in the force control of a pneumatic robot manupulator.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.224-228
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• 2005

동적 감쇠자로서 백홀에 대한 동적 제어 테스트를 수행하였다. 공급라인에서 압력 섭동에 의해 발생되는 가진과 스월 인젝터의 내부 파동 분석을 위해 수력학적 진동발생기와 1차원 가시화 모델 인젝터가 제작되었다. 음향학적 대신에 동적 감쇠자로서 백홀의 영향에 초점을 두었기 때문에 액막의 분열길이와 액막 두께를 측정하여 정상 상태와 가진 상태의 결과를 비교하였다.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권6호
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• pp.372-375
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• 2005

The tracking performance of optical disk drive(ODD) system can be improved using disturbance observer(DOB). But, DOB was not easily applied in the ODD system because the additional microprocessor was needed. In this paper, we propose an error-based modified disturbance observer(EM-DOB) for ODD system. Due to the simplified structure of EM-DOB, the system is easily implemented to the digital control algorithm or the analog circuit. In these algorithms, disturbances rejection performance of system can be tuned as Q filter parameters are selected. Based on analysis of sensitivity function, three guidelines of Q filter design are suggested. Experimental results of DOB and EM-DOB are evaluated under the forced disturbances.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.163-167
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• 2008

30톤급 액체로켓엔진 연소기 연소시험을 통해 측정된 압력섭동 특성에 대한 결과를 제시하였다. 연소실 압력과 O/F비를 변화시키면서 수행된 46회의 연소시험의 결과를 바탕으로 30톤급 연소기의 연소 안정성을 대해 평가하였다. 정상 연소과정에서 발생하는 압력섭동 RMS 값이 연소실 압력의 2.6% 이내로서 정상상태에서 연소현상이 안정적임을 보여주었다. 또한 펄스건 강제교란을 통한 압력섭동의 감쇠 시간 계산결과가 3.5 msec 이내라는 것을 통해 동적으로 안정적인 연소기임을 확인하였다.