제진장치 설치 해양구조물의 생애주기 지진위험도

김동현(Dong-Hyawn Kim) 한국해양공학회 2010 韓國海洋工學會誌 Vol.24 No.5

The analysis of the seismic risk of an offshore structure with a control device is presented. First, a probability density function was developed to represent seismic hazard, and seismic fragility under artificial earthquake conditions was determined. Fragility curves for an offshore structure with both passive and active control devices were determined. Displacement criteria were set to evaluate the performance of the structure. Based on numerical analysis, the seismic risk to the structure was considerably reduced when the structure had a seismic control device. The seismic risk to the actively controlled structure was decreased by 80% compared to the uncontrolled case. Reasonable performance evaluations of offshore structure with control devices can be conducted through risk analysis.

Development of Active Seismometer possessing Expanded Dynamic Range by using Digital Feedback Control

Satoshi FUTAI,Kazuto SETO,Ryo WATANABE,Yuichi IWASAKI,Mitsuru MIYAZAKI,Toru WATANABE 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.춘계 No.-

This paper proposes a new type of active seismo-meter measuring vibration possessing long period and wide dynamic range. In order to lower the natural frequency and expand the detectable amplitude, the sensor with the low natural frequency is realized by using feedback control. Besides, analog feedback control circuit consisted of resistors, capacitors and operational amplifiers possess temperature dependency, while digital feedback control circuit consisted of computer and digital signal processor is temperature independent. In this report, a novel digital feedback control circuit is developed and tested to avoid temperature dependency. It has been demonstrated that the detectable frequency range and the dynamic range of that is expanded.

Cable with discrete negative stiffness device and viscous damper: passive realization and general characteristics

Chen, Lin,Sun, Limin,Nagarajaiah, Satish Techno-Press 2015 Smart Structures and Systems, An International Jou Vol.15 No.3

Negative stiffness, previously emulated by active or semi-active control for cable vibration mitigation, is realized passively using a self-contained highly compressed spring, the negative stiffness device (NSD).The NSD installed in parallel with a viscous damper (VD) in the vicinity of cable anchorage, enables increment of damper deformation during cable vibrations and hence increases the attainable cable damping. Considering the small cable displacement at the damper location, even with the weakening device, the force provided by the NSD-VD assembly is approximately linear. Complex frequency analysis has thus been conducted to evaluate the damping effect of the assembly on the cable; the displacement-dependent negative stiffness is further accounted by numerical analysis, validating the accuracy of the linear approximation for practical ranges of cable and NSD configurations. The NSD is confirmed to be a practical and cost-effective solution to improve the modal damping of a cable provided by an external damper, especially for super-long cables where the damper location is particularly limited. Moreover, mathematically, a linear negative stiffness and viscous damping assembly has proven capability to represent active or semi-active control for simplified cable vibration analysis as reported in the literature, while in these studies only the assembly located near cable anchorage has been addressed. It is of considerable interest to understand the general characteristics of a cable with the assembly relieving the location restriction, since it is quite practical to have an active controller installed at arbitrary location along the cable span such as by hanging an active tuned mass damper. In this paper the cable frequency variations and damping evolutions with respect to the arbitrary assembly location are then evaluated and compared to those of a taut cable with a viscous damper at arbitrary location, and novel frequency shifts are observed. The characterized complex frequencies presented in this paper can be used for preliminary damping effect evaluation of an adaptive passive or semi-active or active device for cable vibration control.

Cable with discrete negative stiffness device and viscous damper: passive realization and general characteristics

Lin Chen,Limin Sun,Satish Nagarajaiah 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.3

Negative stiffness, previously emulated by active or semi-active control for cable vibrationmitigation, is realized passively using a self-contained highly compressed spring, the negative stiffnessdevice (NSD).The NSD installed in parallel with a viscous damper (VD) in the vicinity of cable anchorage,enables increment of damper deformation during cable vibrations and hence increases the attainable cabledamping. Considering the small cable displacement at the damper location, even with the weakening device,the force provided by the NSD-VD assembly is approximately linear. Complex frequency analysis has thusbeen conducted to evaluate the damping effect of the assembly on the cable; the displacement-dependentnegative stiffness is further accounted by numerical analysis, validating the accuracy of the linearapproximation for practical ranges of cable and NSD configurations. The NSD is confirmed to be a practicaland cost-effective solution to improve the modal damping of a cable provided by an external damper,especially for super-long cables where the damper location is particularly limited. Moreover, mathematically,a linear negative stiffness and viscous damping assembly has proven capability to represent active orsemi-active control for simplified cable vibration analysis as reported in the literature, while in these studiesonly the assembly located near cable anchorage has been addressed. It is of considerable interest tounderstand the general characteristics of a cable with the assembly relieving the location restriction, since itis quite practical to have an active controller installed at arbitrary location along the cable span such as byhanging an active tuned mass damper. In this paper the cable frequency variations and damping evolutionswith respect to the arbitrary assembly location are then evaluated and compared to those of a taut cable witha viscous damper at arbitrary location, and novel frequency shifts are observed. The characterized complexfrequencies presented in this paper can be used for preliminary damping effect evaluation of an adaptivepassive or semi-active or active device for cable vibration control.

수리온 능동진동제어시스템 성능 시연 결과

곽동일,정세운,김도형,황유상 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.11

헬리콥터 진동의 주요 가진원은 주로터이며 조종사와 승객들의 안락함을 위해 주로터에 의한 진동에 대응하는 것은 아주 중요한 문제이다. 대부분의 헬리콥터에는 수동형 또는 능동형 진동억제장치가 적용되어 있다. 국외선진업체들은 수동형 대비 적은 중량으로 고효율이면서 주기적 유지 보수가 불필요한 능동진동제어시스템으로 수동형 진동저감장치를 대체하는 추세에 있다. 또한 능동진동제어시스템은 모든 비행조건에서 만족할만한 성능을 발휘하기 때문에 만족도가 아주 높다. 수리온에서 이러한 성능이 발휘 되는지 확인하고자 능동진동제어시스템의 성능 시연 비행시험을 수행하였다. 본 논문에서는 수리온에 대한 능동진동제어시스템 성능 시연 시험의 수행과정, 수행기법 그리고 시험결과를 제시한다. The main source of vibration for the Helicopter is the main rotor and the main rotor-induced vibration is one of the main challenges for pilot and passenger comfortable in cockpit and cabin. Most helicopters have passive or active anti-vibration devices. There is a growing tendency for foreign advanced helicopter manufactures to replace passive with Active Vibration Control System(AVCS) which has the benefit of higher performance with lower weight and periodic maintenance unnecessary compared to passive. Also, AVCS is high satisfactory for its high performance overall maneuvers. Surion AVCS flight test campaign was performed in order to demonstrate a performance of AVCS for Surion. This paper shows procedure, technique and flight test results for AVCS performance demonstration flight testing.

Spectral analysis of semi-actively controlled structures subjected to blast loading

Ewing, C.M.,Guillin, C.,Dhakal, R.P.,Chase, J.G. Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.1

This paper investigates the possibility of controlling the response of typical portal frame structures to blast loading using a combination of semi-active and passive control devices. A one storey reinforced concrete portal frame is modelled using non-linear finite elements with each column discretised into multiple elements to capture the higher frequency modes of column vibration response that are typical features of blast responses. The model structure is subjected to blast loads of varying duration, magnitude and shape, and the critical aspects of the response are investigated over a range of structural periods in the form of blast load response spectra. It is found that the shape or length of the blast load is not a factor in the response, as long as the period is less than 25% of the fundamental structural period. Thus, blast load response can be expressed strictly as a function of the momentum applied to the structure by a blast load. The optimal device arrangements are found to be those that reduce the first peak of the structural displacement and also reduce the subsequent free vibration of the structure. Semi-active devices that do not increase base shear demands on the foundations in combination with a passive yielding tendon are found to provide the most effective control, particularly if base shear demand is an important consideration, as with older structures. The overall results are summarised as response spectra for eventual potential use within standard structural design paradigms.

Development of Active Seismometer possessing Expanded Dynamic Range by using Analog Feedback Control

Akihiro HARA,Ryo WATANABE,Kazuto SETO,Toru WATANABE,Yuichi IWASAKI,Mitsuru MIYAZAKI 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.춘계 No.-

This paper proposes a new type of active seismometer measuring vibration possessing long period and wide dynamic range. In order to lower the natural frequency and expand the detectable amplitude, the sensor with the low natural frequency is realized by using feedback control. Moreover, to compensate phase-delay, third order phase-lag compensator is added to shape measured output. It has been demonstrated that the detectable frequency range of the sensor is extended from 0.1[㎐] to 10[㎐], while the dynamic range of that is expanded up to 57[㏈], namely vibrations that possess 700times larger amplitude than the maximum stroke of the sensor. New sensor body is produced and tested.

Spectral analysis of semi-actively controlled structures subjected to blast loading

C.M. Ewing,C. Guillin,R.P. Dhakal,J.G. Chase 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.33 No.1

This paper investigates the possibility of controlling the response of typical portal frame structures to blast loading using a combination of semi-active and passive control devices. A one storey reinforced concrete portal frame is modelled using non-linear finite elements with each column discretised into multiple elements to capture the higher frequency modes of column vibration response that are typical features of blast responses. The model structure is subjected to blast loads of varying duration, magnitude and shape, and the critical aspects of the response are investigated over a range of structural periods in the form of blast load response spectra. It is found that the shape or length of the blast load is not a factor in the response, as long as the period is less than 25% of the fundamental structural period. Thus, blast load response can be expressed strictly as a function of the momentum applied to the structure by a blast load. The optimal device arrangements are found to be those that reduce the first peak of the structural displacement and also reduce the subsequent free vibration of the structure. Semi-active devices that do not increase base shear demands on the foundations in combination with a passive yielding tendon are found to provide the most effective control, particularly if base shear demand is an important consideration, as with older structures. The overall results are summarised as response spectra for eventual potential use within standard structural design paradigms.

헬리콥터 능동진동제어시스템의 수리온 적용 및 성능 분석

김도형(Do-Hyung Kim),김태주(Tae-Joo Kim),백승길(Seung-Kil Paek),곽동일(Dong-Il Kwak),정세운(Se-Un Jung) 한국항공우주학회 2015 韓國航空宇宙學會誌 Vol.43 No.6

헬리콥터 진동의 주요 가진원 중 가장 결정적인 요인은 주로터이며 이러한 로터 유발 진동은 승무원과 승객의 안락함을 보장하기 위해 회전익 항공기에서 해결해야할 과제 중 하나이다. 종래의 헬리콥터에서는 수동형 진동저감장치가 주로 사용되어 왔고 수리온 항공기에도 여러 가지 형태의 수동형 진동저감장치가 적용되어 있다. 최근 국외 항공기 제조업체에서는 수동형 진동저감장치 대비 작은 중량으로 우수한 진동저감 성능을 발휘할 수 있는 능동진동제어시스템(AVCS)의 적용을 확대하고 있는 추세이다. AVCS는 중량 절감 외에도 항공기 형상, 비행 상태 변화 시에도 만족할만한 성능을 유지할 수 있는 장점이 있다. 이러한 AVCS를 수리온에 적용 시 어느 정도의 성능을 발휘하는지 확인하기 위한 성능시연 프로그램을 수행하였고, 최적의 센서와 작동기 조합을 찾기 위한 최적화 과정을 수행하였다. 지상 및 비행시험을 통해 계측된 데이터를 이용하여 최적의 센서 및 작동기 조합을 도출하고 비행시험 결과와 비교하였다. The most decisive factor of major sources of a helicopter is the main rotor system and the rotor-induced vibration is one of the technical challenges which should be resolved to ensure comfort for crews and passengers. Passive vibration reduction devices are adopted in conventional helicopters and several types of passive devices are also used in Surion. In recent years, foreign helicopter manufactures have increasingly applied the application of AVCS (active vibration control system) because of their superior performance with lower weight compared to passive device. In addition to weight reduction, AVCS has advantages maintaining its performance over aircraft configuration changes and flight condition changes. The technology demonstration program was performed in order to validate the performance of AVCS when applied to Surion, and optimization process for finding optimal configuration of sensors and actuators. Optimal configuration was produced using ground and flight test data, and its performance was evaluated and compared with flight test result.

음향센서를 활용한 CNC 공구떨림 감지 및 안정화 기법

김정준,조기환 한국정보전자통신기술학회 2019 한국정보전자통신기술학회논문지 Vol.12 No.2

Recently, there is an increasing need for highly precise processing with the rapid development of precision machinery, electrical and electronics, and semiconductor industries. Cutting machine control relies on the operator's sense and experience in tradition, but it has been greatly enhanced by the adoption of CNC(Computerized Numeric Controller). In addition, cutting dynamics technology has been paid attention to reflect the operating state of machine in real time. This paper presents a method to detect and stabilize tool vibration by attaching an acoustic sensor to a CNC machine. The sensed acoustic data is synchronized with the tool position and the abnormal vibration frequency is separated from the collected acoustic frequency, then analyzed to detect the tool vibration. Also the reliability the tool vibration detection and stabilization is improved by applying the cutting dynamic method. The proposed method is analyzed and evaluated in terms of the surface roughness. 최근 정밀기계, 전기전자, 반도체 등의 급속한 산업의 발달로 전장장치의 고정밀도 가공의 필요성이 증대하고 있다. 작업자의 감각과 경험에 의존하던 절삭 공작기계 제어는 CNC(Computerized Numeric Controller: 컴퓨터 수치제어) 도입으로 가공 정밀도가 획기적으로 개선되고 있다. 또한 공작 기계의 운전 상태를 실시간 반영하는 가공 동특성(cutting dynamics)기법이 관심을 받고 있다. 본 논문은 CNC 공작기계에 음향센서를 부착하여 공구떨림 감지 및 안정화하는 방안을 제시한다. 공구 이송 위치와 음향센서 데이터를 동기화 하고 수집된 음향 주파수에서 이상 진동음에 대한 주파수를 분석하여 떨림을 감지한다. 또한 가공 동특성 기법을 적용하여 공구떨림 감지와 안정화의 신뢰성을 높인다. 제안한 기법은 금형 가공의 공구떨림 안정화 전후 가공 표면조도의 향상 관점에서 분석 평가한다.