• 한국기계가공학회지
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• 제14권1호
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• pp.57-62
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• 2015

The wet brakes used on a forklift often produce noise upon engagement. The elimination or reduction of this squeal noise is an important task for the improvement of the comfort of those operating these machines. In this paper, a test rig was developed for the testing of brake noise, and the squeal noise was measured with this apparatus. Automatic transmission fluid and grooves in the material of the friction-plate pad were found to be the main factors causing squeal noise. In order to identify the characteristics of this type of noise, signal analyses of the noise were conducted using different frequency spectra. The experimental results showed that the viscosity of the automatic transmission fluid and the groove pattern on the friction-plate pad largely affected the reduction of the wet brake squeal noise made by an industrial forklift.

• 한국소음진동공학회논문집
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• 제24권3호
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• pp.227-235
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• 2014

The demand of natural gas is gradually increasing as a clean fuel in the world. Therefore, LNG storage tanks and related facilities of the importance of leading a community-based facility have emerged. The seismic design of LNG storage tank including seismic analysis have been developed steadily. But, the seismic analysis and design techniques for LNG storage tanks are lacking, in Korea. Consequently, it is necessary to develop an analysis model that LNG storage tanks in isolation system can describe the behavior. Further, LNG storage tank capable of ensuring safety and economy, it is necessary to develop design techniques. The studies have suggested seismic design procedures of LNG storage tanks with isolation system including triple-FPB and idealized complex hysteresis model of triple-FPB.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.89-96
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• 2002

A two-degree of freedom model is suggested to understand the basic dynamical behaviors of the interaction between two masses of the friction induced vibration system. The two masses may be considered as the pad and the disk of the brake, The phase space analysis is performed to understand complicated dynamics of the non-linear model. Attractors in the phase space are examined for various conditions of the parameters of the model especially by emphasizing on the damping parameters. In certain conditions, the attractor becomes a limit cycle showing the stick-slip phenomena. In this paper, not only the existence of the limit cycle but also the size of the limit cycle is examined to demonstrate the non-linear dynamics that leads the unstable state. For the two different cases of the system frequency ((1)two masses with same natural frequencies, (2) with different natural frequencies), the propensity of limit cycle is discussed in detail. The results show an important fact that it may make the system worse when too much damping is present in the only one part of the masses.

• Tribology and Lubricants
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• 제36권5호
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• pp.274-278
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• 2020

This study investigates the possibility of reducing squeal noise generated at the contact point between an elastomer and glass by using the properties of a magneto-rheological elastomer (MRE) whose stiffness changes with the application of a magnetic field. Previously, squeal noise was mainly observed in the unstable section caused by the weakening of friction due to velocity. Previous studies have shown that squeal noise decreases as the stiffness increases. Accordingly, this study is conducted to control the unstable area of the friction curve and to reduce the noise by inducing the stiffness change of the MRE by applying a magnetic field. The friction, vibration, and noise characteristics are measured using a reciprocating friction tester. The frequency ranges of vibration and noise measured with the accelerometer and sound sensor show similar results. When a magnetic field is applied to the MRE, there is significantly lower noise compared with the case without the application of the magnetic field. The average coefficient of friction decreases with the application of the magnetic field. The maximum coefficient of friction increases rapidly at the turning point and decreases when the magnetic field is applied. This shows that the mechanical properties of the MRE change due to the magnetic field, and the noise and friction coefficient also decrease.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.986-992
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• 2014

This research investigates experimentally and numerically the tilting angle, eccentricity ratio, flying height of axial direction, friction torque, and critical mass of the HDD disk-spindle system due to HDD positioning angle. The tilting angle and the eccentricity ratio are the maximum when the HDD positioning angle is $90^{\circ}$ respect to horizontal position because the external force in radial direction and the torque applied to the rotating part are the maximum when the HDD positioning angle is $90^{\circ}$. The flying height increases with the increase of the HDD positioning angle because the direction of gravity applied to the rotating part changes. The friction torque increases with the increase of the HDD positioning angle until it becomes $60^{\circ}$, and decreases with the increase of the HDD positioning angle after it becomes $60^{\circ}$. The stability is the maximum when the HDD positioning angle is $90^{\circ}$.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1044-1048
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• 2006

Nuclear power generation is very dangerous in occasion that skirt of structure by earthquake although it is high effective generation that can make a lot of energies with few raw material. when design, it must consider a lot of problems caused by an earthquake. The seismic analysis of the structure has been great concern in the engineering society with an effort to reduce the severe damages from an earthquake. So the earthquake resistant design is one of the crucial design procedures of a gate valve used in nuclear power generation. The gate valve which has the contact area between stem and bellows. Because of the contact area. The gate valve should be given high stress and frictional wear. In this thesis, Considering the gate valve which has some contact distance between stem and bellows. The gate valve which has some contact distance is analyzed by a commercial FEM code of Ansys and Then compared to the gate valve behavior which doesn't have contact distance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.464-469
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• 2012

발전소에 있어서, 발전소가 높은 신뢰성이 있기 위해서는 안정적인 회전체의 동적 운동이 확보되어야 하므로, 장기간 안전하게 운전하기 위하여 축 진동은 매우 중요한 요소중의 하나이다. 하지만 어느 복합발전소에서는 오일 탄화물에 의한 비정상적인 1X 성분의 축 진동 상승으로 가스터빈이 여러번 정지되었다. 본 논문에서는 가스터빈 Exhaust 케이싱 베어링에서 발생한 이상진동에 대하여 어떻게 현장조치를 하였는지를 기술하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.132-138
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• 2013

Natural gas as a clean fuel of the world demand for the trend is gradually increasing demand for clean energy in the country and there is growing interest. Therefore, LNG storage tanks and related facilities in the country of the importance of leading a community-based facility has emerged. So common sense that an earthquake with a seismic isolation device LNG storage tank similar to the actual behavior of the analytical model which can describe the development and construction of storage tanks to enhance the safety and economic design techniques need to be developed. In this study, a base isolation system, seismic analysis procedure of LNG storage tanks, and Triple-FPB developed a mathematical model of the present crystallized and complexity factors to the sum over histories model simplifies the complex behavior of the LNG storage tank with base isolation system how to interpret the seismic isolation is proposed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.744-749
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• 2005

In this paper, a lens actuator for mobile devices is proposed using stack type piezoelectric materials. In general, the deformation of PZT actuators is not enough for lens motion when the allowed voltage is applied. The small stroke problem can be solved by accumulating a lot of small displacements in high frequency. In this paper, a new inch-worm type model for focusing actuator is suggested based on the interaction of inertial and frictional forces. Theoretical analysis and simulation using ANSYS are performed to verify the feasibility of the inch-worm PZT actuator model. Various types of clamps are considered to determine the effect of frictional force on the motion, and appropriate clamp-actuator models are proposed. The proposed models are experimentally verified and the experimental results show high correspondence with theoretical and simulated values. The inch-worm type focusing actuator enable a large stroke with 7.79 mm/sec with 10kHz and 10V.

• 한국소음진동공학회논문집
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• 제12권7호
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• pp.502-509
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• 2002

A two-degree of freedom model Is suggested to understand the basic dynamical behaviors of the interaction between two masses of the friction induced vibration system. The two masses may be considered as the pad and the dusk of the brake. The phase space analysis is performed to understand complicated dynamics of the non-linear model. Attractors in the phase space are examined for various conditions of the parameters of the model especially by emphasizing on the damping parameters. In certain conditions, the attractor becomes a limit cycle showing the stick-slip phenomena. In this Paper, not only titre existence of the limit cycle but also the sloe of the limit cycle is examined to demonstrate the non-linear dynamics that leads the unstable state. For the two different cases of the system frequency[(1) Two masses with same natural frequencies, (2) with different natural frequencies] . the propensity of limit cycle Is discussed In detail. The results show an important fact that it may make the system worse when too much damping Is present in the only one part of the masses.