• 소음진동
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• 제4권4호
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• pp.425-433
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• 1994

A detailed investigation of a reed resonance for a vertical pump design has been conducted. The structural features of this class of pump lead to typical dynamic characteristics. Of particular importance is the fact that the pump assembly is suspended on a high column above the floor with a heavy motor on the top. Considerable amount of mass forces is involved and the vibration can cause damage to the pumps or to the foundation. It is shown that the reed resonance of the pump-motor system plays important role for design and troubleshooting purposes.

• 산업기술연구
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• 제26권A호
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• pp.75-80
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• 2006

A vibration monitoring is performed on a 1kW class stand alone wind turbine(W/T). When a W/T model is developed, general performance under various wind condition should be verified to introduce the product in the market. Especially, vibration characteristics within operating speed range are very important in the aspect of structural stability as well as generator's electrical efficiency. This paper examines the vibration performance of a home made 1kW W/T. Various data of the W/T model are acquired in real time using a remote vibration monitoring system installed in Daekwanryung test site. Vibration stability of the W/T structure is diagnosed based upon the data and the result is used to estimate the applicability of the W/T model.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권4호
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• pp.383-388
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• 2014

In This paper, the output characteristics and vibrations were compared and analyzed according to operation method in 100W class. The voltage source is applied only two phase in BLDC drive system therefore commutation torque ripple and imbalance of RMF occurred. Due to this efficiency was significantly degraded because mechanical loss is increased, besides the vibration and noise were greatly generated. The vibration and output characteristics were compared and analyzed according to three phase and BLDC drive system.

• 한국소음진동공학회논문집
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• 제27권1호
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• pp.107-113
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• 2017

The dynamic characteristics including natural frequencies and excitation frequencies are evaluated for a small 10 kW vertical axis wind turbine. Acceleration responses were measured at 12 distributed locations for impact vibration tests, ambient vibration tests during non-operational and operational conditions, and braking tests during operational condition. The natural frequencies for the lowest 2 bending modes and the first torsional mode were estimated and also the excitation frequencies, i.e. 1P, 2P, 4P, were also estimated according to the rotational speed using the responses under operational conditions (i.e. power generation condition).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.313-317
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• 2001

Magneto-Rheological fluid (MR fluid) is known as a class of functional fluid with controllable apparent viscosity of the fluid by the applied magnetic field strength. Extensive researches with the functional fluids have been done on applications of the fluid to mechanical components such as suspension, absorber, engine mount, clutch, break, valve, etc. In this study, a new torsional damper using MR fluid is proposed, and the response property of the damper was theoretically investigated. The present damper is quit effective for reducing the driveline vibration in a wide range of the engine speed.

• Journal of Mechanical Science and Technology
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• 제14권10호
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• pp.1061-1071
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• 2000

Linear cyclic systems (LCS's) are a class of systems whose dynamic behavior changes periodically. Such a cyclic behavior is ubiquitous in systems with fundamentally repetitive motion. Yet, the knowledge of the noise and vibration transmission paths in LCS's is quite limited due to the time-varying nature of their dynamics. The first part of this two-part paper derives a generic expression that describes how the noise and/or vibration are transmitted between two (or multiple) points in the LCS's. In Part II, experimental validation of the theoretical development of Part I is provided. The noise and vibration transmission paths of the scroll and rotary compressors (two typical LCS's) are examined to show that the LCS's indeed generate a series of amplitude modulated input signals at the output, where the carrier frequencies are harmonic multiples of the LCS' fundamental frequency. The criterion proposed in Part I to determine how well a given LCS can be approximated as a linear time-invariant systems (LTIS) is applied to the noise and vibration transmission paths of the two compressors. Furthermore, the implications of the experimental validations/applications are discussed in order to assess the applicability of the noise/vibration source and transmission path identification techniques based on the assumption that the system under consideration is linear and time-invariant.

• 산업기술연구
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• 제25권A호
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• pp.81-86
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• 2005

A vibration monitoring system for a small class of wind turbine (W/T) is established and operated. The monitoring system consists of monolithic integrated chip accelerometer for vibration monitoring, anemometers for wind data acquisition and auxiliary sensors for atmospheric data. Using the monitoring system, vibration response of a 6kW W/T generator is investigated. Acceleration data of the W/T tower under various operation condition is acquired in real time using LabVIEW and is remotely transferred from the test site to the laboratory in school by internet. Vibration state of the tower structure is diagnosed within the operating speed range. Resonance frequency range of the test model is investigated with the wind speed data of the test site.

• Structural Engineering and Mechanics
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• 제11권4호
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• pp.341-356
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• 2001

A new class of semi-active tuned mass dampers, named as "Ground Hook Tuned Mass Damper" (GHTMD) is introduced. This TMD uses a continuously variable semi-active damper (so called 'Ground-Hook') in order to achieve more reduction in the vibration level. The ground-hook dampers have been used in the auto-industry as a means of reducing the vibration of primary suspension systems in vehicles. This paper investigates the application of this damper as an element of a tuned damper for the vibration reduction of force-excited single degree of freedom (SDOF) models that can be representative of many structural systems. The optimum design parameters of GHTMDs are obtained based on the minimization of the steady-state displacement response of the main mass. The optimum design parameters which are evaluated in terms of non-dimensional values of the GHTMD are obtained for different mass ratios and main mass damping ratios. Using the frequency responses of the resulting systems, performance of the GHTMD is compared to that of equivalent passive TMD, and it is found that GHTMDs are more efficient. A design methodology to obtain the tuning parameters of GHTMD using the relationships developed in this paper is presented.

• Journal of Advanced Marine Engineering and Technology
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• 제41권4호
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• pp.310-315
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• 2017

최근 건조되는 선박은 연료소비량을 절감하고 안락한 운항을 위해서 고효율 프로펠러를 부착하고 있다. 이와 같이 고효율 프로펠러가 탑재됨에 따라 이전의 프로펠러 특성을 고려한 프로펠러 감쇠방법을 이용하여 해당 축계의 비틀림진동 해석을 할 경우에는 해석 오차가 많이 발생되고 있다. 이러한 오차는 고효율 프로펠러의 개발이 지속됨에 따라 더욱 커질 것으로 예상된다. 본 논문에서는 비틀림진동 해석에 적용되고 있는 각종 프로펠러 감쇠 적용방법들에 따른 해석 편차를 검토하였다. 또한 고효율 직결식 10MW급 프로펠러를 적용한 선박들을 대상으로 프로펠러 감쇠 적용방법에 따른 해석치와 계측 결과를 비교 검토하여 현 시점에서 사용상 적절한 프로펠러 감쇠방법을 제시하였다.

• 한국추진공학회지
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• 제22권6호
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• pp.126-133
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• 2018

액체로켓엔진은 비행 중에 극심한 진동 환경뿐만 아니라 추진제의 고압, 추력, 극저온 산화제나 고온 연소 가스에 의한 열하중 등의 다양한 정적 하중을 겪는다. 엔진 개발 단계에서는 구조 안정성을 위해 엔진 시스템에 대한 구조 해석과 지상 연소 시험에서 측정된 변형율을 분석이 필요하다. 여기서는 75톤급 엔진의 지상 연소 시험에서 얻어진 변형율 특성을 분석하였다.