• 한국소음진동공학회논문집
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• 제15권4호
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• pp.483-491
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• 2005

In this paper a dynamic behavior of a double-cracked cantilever pipe with the tip mass and a moving mass is presented. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Lagrange's equation. The influences of the moving mass, the tip mass and double cracks have been studied on the dynamic behavior of a cantilever pipe system by numerical method. The cracks section are represented by the local flexibility matrix connecting two undamaged beam segments. Therefore, the cracks are modelled as a rotational spring. This matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory. We investigated about the effect of the two cracks and a tip mass on the dynamic behavior of a cantilever pipe with a moving mass.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.555-558
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• 2013

A type of electric propulsion employed by specialized purpose vessels or offshore is the azimuth thruster. Azimuth thruster application had been increasing recently and resulted to excellent vessel maneuverability. However, this system is very complex and some of its major component being exposed under the seawater level presents difficulty in sealing design. For Polar class icebreaker operating in extreme sea condition, this requires a high level of reliability and safety. In this study, the characteristics of lubricating orifice pipe structural vibration installed at the lower reduction gear were investigated and analyzed through beam analysis theory and comparison of experiments. Propeller excitation and the resonant modes of vibration causing excessive vibration and suitable countermeasures to prevent damage due to vibration fatigue on the pipe are presented.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.958-963
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• 2003

In this paper a dynamic behavior of simply supported cracked pipe conveying fluid with the moving mass is presented. Based on the Timoshenko beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments i.e. the crack is modelled as a rotational spring. This flexibility matrix defines the relationship between the displacements and forces across the crack section and is derived by applying fundamental fracture mechanics theory. And the crack is assumed to be in th first mode of fracture. As the depth of the crack and velocity of fluid are increased the mid-span deflection of the pipe conveying fluid with the moving mass is increased. As depth of the crack is increased, the effect that the velocity of the fluid on the mid-span deflection appears more greatly.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.779-780
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• 2014

This paper dealt with numerical estimation of pressure pulsation of the refrigerant in a suction pipe of the compressor. To evaluate the effect of reduction of pressure pulsation, a pipe system with tube was simulated using F.S.I.(Fluid-structure interaction) analysis. A commercial program was used for calculating behavior of pressure. The numerical simulation for pressure ratio of before and after going though internal structure were carried out. As a result, it was verified that the pressure after passing structure is less than the pressure before passing internal structure depending on the longitudinal frequency of structure.

• 한국소음진동공학회논문집
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• 제16권10호
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• pp.1050-1056
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• 2006

In this paper, a new method for the stability analysis of a pipe conveying fluid which pulsates periodically is presented. The finite element model is formulated liking into consideration of the effects of the fluid pulsating in a pipe. The damping and stiffness matrices in the finite element equation vary with time due to pulsating fluid. Coupled effects of several harmonic components in the velocity of fluid to a pipe is discussed. A new unstable region appears which will not appear in the stability analysis of single pulsating frequency. A method to directly estimate the forced response of pipe is also discussed. The results presented in this paper are verified by the time domain analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1154-1158
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• 2006

This investigation suggests a new non-contact type sensor that can measure flexural vibrations of a non-ferromagnetic pipe. The sensor works on the reversed Lorentz force mechanism; however, anti-symmetric bias magnetic field suggested in this work should be applied to measure bending vibration of a non-ferromagnetic pipe. The importance of the suggested magnetic field is verified by a series of experiments. The sensor is applied to the bending vibration measurement and modal testing of an aluminum pipe and shows satisfactory working performance compared to others.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.254-257
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• 2006

In this paper a dynamic behavior(natural frequency) of a cracked cantilever and simply supported pipe conveying fluid is presented. In addition, an analysis of the flutter and buckling instability of a cracked pipe conveying fluid subjected to a follower compressive load is presented. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Lagrange's equation. The crack section is represented by a local flexibility matrix connecting two undamaged beam segments. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations.

• 한국소음진동공학회논문집
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• 제25권8호
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• pp.559-567
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• 2015

The paper deals with an ultrasonic transducer invented for measuring both flow velocity and pipe thickness. The structure of the transducer is based on the conventional transducers for measuring flow velocity by obliquely transmitting ultrasonic waves to the flow direction. The transducer additionally generates ultrasonic waves transmitting vertically to a pipe for measuring pipe thickness. By measuring flow velocity with the invented transducer and a conventional oblique-incidence transducer and comparing their results, the accuracy of the flow velocity measurement of the invented one was evaluated. By measuring specimen thickness with the invented transducer and a conventional normal-incidence transducer and comparing their results, the accuracy of the thickness measurement of the invented one was evaluated.

• 한국소음진동공학회논문집
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• 제11권6호
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• pp.208-215
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• 2001

The paper presents both theoretical and experimental study fur dynamic instabilities of a vortical cantilevered pipe with two attached lumped masses conveying fluid. The two attached lumped masses can be considered as valves or some mechanical paras in real pipe systems. Eigenvalue behaviors depending on the flow velocity are investigated for the change of Positions and magnitudes of an attached lumped mass and a tip mass. In order to verify appropriate of numerical solutions, experiments were accomplished. Theoretical predictions have a good agreement with experimental ones.

• 화약ㆍ발파
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• 제31권2호
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• pp.25-31
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• 2013

본 시공사례는 "성남~여주 복선전철 제 O공구 노반건설공사"중 도로 하부통과 구간으로서 터널의 노선을 따라 진동 및 소음으로 인한 피해 영향권 내에 아파트, 도자기 생산공장 및 국도 등 주요 보안물건 등이 위치하고 있다. 특히, 터널 노선 12m 상부의 국도를 따라 도시가스관(${\varphi}500mm$)이 매설되어 있어, 진동허용기준(1.0cm/sec) 이하로 안전하게 굴착하기 위하여 전자발파 공법을 적용하였으며, 굴착에 따른 지반의 변위를 최대한 방지하기 위하여 정밀 진동제어와 함께 신속한 굴착 및 보강이 이루어짐으로서 안전하게 완료되었다.