• 한국소음진동공학회논문집
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• 제16권5호
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• pp.537-543
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• 2006

The impact sound of the golf club is one of the major factors to purchase it. Sound quality metrics has been mostly developed for harmonic sounds. Sound quality evaluation techniques for the impact sound have been contrived in this study. Jury test, one of the typical subjective evaluation scheme, is carried out for evaluating the sound quality of 13 different golf drivers, which classification results are assumed to be correct answers. Conventional objective evaluation methods such as Zwicker loudness sensory pleasantness are calculated. Wavelet analysis and instantaneous loudness are applied in order to evaluate the sound quality of transient sounds, which scheme shows better correlation with the results from jury test.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.185-190
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• 2011

The important use of the desuperheater(multi spray type) changes the superheated steam into the saturated steam. It is more efficient and suitable for using the process. Also, it is more convenient and stable regarding the process temperature control. In this study, transient and quasi-static analysis were done for the evaluation of structural integrity of the multi spray type desuperheater of the power plant. Computational analysis was used to calculate the thermal stress, and the vibration test was done to evaluate the structural stability. This paper is verified by analysis that water spray nozzle(${\phi}=28mm$) shows the best ability. The results show that structural stability of the desuperheater under the real operating condition was proven.

• 한국소음진동공학회논문집
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• 제14권9호
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• pp.827-836
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• 2004

In this paper, we design a robust multi-objective track-following controller that satisfies transient response specifications and diminishes the influence of sinusoidal disturbance. To this end, a robust control problem with the multiple constraints is considered. We show that a sufficient condition satisfying the robust control problem can be expressed by linear matrix inequalities. Finally, the robust track-following controller can be designed by solving an LMI optimization problem. The effectiveness of the proposed controller design method is verified though experiments.

• 한국소음진동공학회논문집
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• 제12권8호
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• pp.589-597
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• 2002

주행중인 차량의 동적 거동에 대한 응답을 해석하기 위하여 시간영역에서 뿐만 아니라 주파수 영역에서의 해석이 필요하다. 주파수 영역에서의 해석을 위하여 시간영역에서의 값을 FFT를 이용하여 주파수 영역으로 변화하는 방법이 일반적으로 사용되어 왔다. 본 연구에서는 최대 엔트로피 방법을 이용하여 기존의 FFT 방법보다 차량의 과도응답특성을 시간영역 및 주파수 영역에서 편리하게 해석할 수 있는 방법을 제시하고 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.960-963
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• 2003

Sound intensity method is well known as a visualization technique of sound field and sound propagation in noise control. Sound intensity is a vector quantity that describes the magnitude and the direction of net flow of acoustic energy at a given position. The current measuring method is expensive and difficult to identify the noise source exactly. In this paper, we have studied the noise source identification and the characteristics of noise source of rotary compressor for air conditioner using complex sound intensity method. The new method for instantaneous sound intensity is also proposed and it is useful for transient state and steady state. The criteria of these state, select auto correlation coefficient. The advantage, simplicity and economic attribution of this method are verified by analyzing the characteristics of noise source with instantaneous sound intensity compared to mean sound intensity.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.635-639
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• 2003

When we carry out acoustic holography, step-by-step measurement provides us larger aperture size with same number of microphones. But when we carry out step-by-step measurement, it is blown that sound signal must be stationary. However, when transfer function between input and output signal is time-invariant, we can apply step-by-step measurement to acoustic holography even if sound signal is transient We have to do only some Processing on signals from step-by-step measurements to make the signal data of each step compatiable with other steps. This paper accounts for that processing method.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.173-179
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• 1998

The piping system of a power plant suffers not only thermal expansion according to the temperature variation, but also many kinds of load: steady state vibrations due to the equipment operation or fluid flow, and transient vibrations due to the earthquake or explosion, etc. The snubbers are usually installed on the piping system to allow thermal expansion, and to reduce dynamic responses. Most snubbers are kinds of hydraulic and mechanical type, which can be degraded by leakage and abrasion, and required much cost for maintenance and replacement. Recently the wire rope type snubbers are developed and applied to the power plant, and proved as effective to reduce piping system vibration. Wire rope type snubber uses the bending rigidity and energy dissipation properties of ropes. This paper presents the procedure of design, and the method to apply hysteresis curve to the dynamic response analysis. Experiments were also conducted to confirm design results.

• Steel and Composite Structures
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• 제22권6호
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• pp.1261-1280
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• 2016

We study chaotic motion in a nonlinear laminated composite plate under subsonic fluid flow and a simultaneous external load in this paper. We derive equations of motion of the plate using the von-$K{\acute{a}}rm{\acute{a}}n^{\prime}s$ hypothesis and the Hamilton's principle. Galerkin's approach is adopted as the solution method. We then conduct a divergence analysis to obtain critical velocities of the transient flow. Melnikov's integral approach is used to find the critical parameters in which chaos takes place. Effects of different parameters including the aspect ratio, plate material and the ply angle in laminates on the critical flow speed are investigated. In a parametric study, we show that how the linear and nonlinear stiffness of the plate and the load frequency and amplitude would influence the chaotic behavior of the plate.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 추계학술대회 논문집
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• pp.85-87
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• 2008

This paper presents dynamic characteristics in Switched Reluctance Motor (SRM) with rotor eccentricity and proposes the reduction method of rotor eccentricity effects by the different winding connections. These characteristics investigations are computed by 2D transient magnetic FEM analysis coupled with external circuits. The radial and unbalance magnetic force in the stator, which is the main exciting force of the vibration, is calculated using Maxwell stress method and compared with the performance characteristics according to the serial and parallel connections of windings. The influence of winding method counteracting unbalance forces on the rotor vibration behavior is estimated by the current waveforms of the paralleled paths under rotor eccentricity.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.123-126
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• 2005

This study provides a comprehensive experimental study on the dynamic characteristics of a flexible matrix composite(FMC) driveshaft. A primary objective is to verify the analytic results of the FMC drivetrain based on the equivalent complex modulus approach and the classical lamination theory. A testrig has been constructed, which consists of a FMC shaft, a foundation beam, bearings, external dampers and a driving motor. The frequency response functions and transient responses are obtained from the external excitation and the spinup testings. It turns out that the analytic results are in good agreement with the experimental ones.