• 소음진동
• /
• 제7권3호
• /
• pp.457-466
• /
• 1997

The experimental and analytical study was conducted to determine the noise transmission characteristics of acoustically loaded steel plate of rectangular enclosure and to investigate the sound radiation characteristics through out the enclosure. The vibrations of acoustically loaded plate give rise to sound radiations and generate the reverberant space that the sound field exists very close to a vibrating plate. Acoustic transmission loss is measured from the incident intensity into the plate and the transmitted intensity through out the plate. Sound radiation patterns are measured from both acoustic intensity technique and surface intensity technique. Those resultant patterns and vibrational modes are vital in understanding the relations between vibration and noise in the near field out of vibrating plate.

• 한국소음진동공학회논문집
• /
• 제19권10호
• /
• pp.987-995
• /
• 2009

As an experimental technique to analyze the far-field characteristics of underwater cylindrical array sensors, cylindrical acoustic holography is studied. Inside an laboratory water tank, far-field directivity patterns as well as near-field source images are reconstructed from the measured hologram by hydrophone array. Approximate equation for far-field directivity estimation is derived based on stationary phase method. The simulation and experiment show well usefulness of the proposed method in application of underwater array sensors.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2009년도 춘계학술대회 논문집
• /
• pp.111-116
• /
• 2009

As an experimental technique to analyze the far-field characteristics of underwater cylindrical array sensors, cylindrical acoustic holography is studied. Inside an laboratory water tank, far-field directivity patterns as well as near-field source images are reconstructed from the measured hologram by hydrophone array. Approximate equation for far-field directivity estimation is derived based on stationary phase method. The simulation and experiment show well usefulness of the proposed method in application of underwater array sensors.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 춘계학술대회논문집
• /
• pp.836-842
• /
• 2001

The more sophisticated patterns of propagation model is presented in this paper, which includes three different source characteristics. The spherical, cosine and dipole radiation characteristics compared and sound event level and the maximum sound level are calculated by experiment and calculation. It is shown that patterns of propagation has dipole characteristics for low speed range(below about 150km/h) at electric multiple system. We know that push-pull high speed system(maximum speed: 300km/h) has cosine characteristics of noise propagation. For this purpose, We conduct the experiment of noise and know the empirical formula of noise level and radiation coefficient K. This model of simulation is conducted through point source array model at wheel/rail contact point by using program and experimental formula. We can guess prediction of profile, flat and wear of wheel by above modeling in near field.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2008년도 춘계학술대회논문집
• /
• pp.807-808
• /
• 2008

This is concerned with the radiation pattern of elastic waves in a plate generated by an orientation-adjustable patch-type magnetostrictive transducer. In general, not only the Lamb waves but also shear horizontal (SH) waves are produced by the deformation of the circular magnetostrictive patch bonded to a plate. Among the two types of waves, this paper investigates the radiation patterns of SH waves. A number of experimental results are presented. They are also accurately predicted by a theory developed by the present authors. Experimental findings were explained by a theoretical analysis.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 춘계학술대회논문집
• /
• pp.991-996
• /
• 2004

The international competition in refrigerator markets has continuously required the research for sound quality of a refrigerator to improve the quality of a life. In this paper, A new method for evaluation of the sound quality of a refrigerator is developed based on human sensibility engineering by using ANN(Artificial neural network). Finally it is applied to evaluate the sound qualify of refrigerator on the production line.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 춘계학술대회논문집
• /
• pp.1003-1008
• /
• 2004

In our life, we have used many digital appliances. They helped us to improve the quality of lift but sometimes gave us unsatisfactory result because they produce specific noise. Especially a vacuum cleaner produces a great deal of noise that is very annoying. So we need to study what sound metrics affect human sensibility. In this paper, we will study sound quality index for vacuum cleaner. The subjective evaluation of vacuum cleaner sound can be indicated to objective parameters by sound metrics of psychoacoustics. The artificial neural network can estimate the nonlinear characteristics of relation between subjective evaluation and sound metrics. We applied the artificial neural network to the development of sound quality index for vacuum sound.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 춘계학술대회논문집
• /
• pp.200-205
• /
• 2004

The pantograph for Korean High Speed Train was developed and had been evaluating by through 'G7-R&D project for home grown high speed train technology' In this study, in mechanical aspect, the variation trend of contact force between pantograph and catenary according to the train running speed and driving pattern is conducted. A measuring system for current collecting performance and mechanical characteristics is used for this study, developed and installed on the prototype Korean High Speed Train, and physical characteristics were measured while the KHST runs on the test track. Through this study, remarkable trends of variation are found and analyzed from measured acceleration and vertical contact force between the pan head in pantograph and contact wire in catenary system according to the driving pattern and the train raised a running speed up to 300km/h.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1995년도 추계학술대회논문집; 한국종합전시장, 24 Nov. 1995
• /
• pp.280-283
• /
• 1995

계층형 신경회로망은 학습능력이나 비선형사상능력을 가지고 있고, 그 특징을 이용하여 패턴인식이나 동정 및 제어 등에의 적용이 시도되어 성과를 올리고 있다. 현재, 그 학습법으로 널리 이용되고 있는 것이 역전파학습법으로 최급 강하법이나 공액경사법 등의 최적화 방법이 적용되고 있지만, 학습에 많은 시간이 걸리는 점, 국소적 최적해(local minima)에 해의 수렴이 이루어져 오차가 충분히 작게 되지 않는 점 등이 문제점으로 지적되고 있다. 본 논문에서는 Hu에 의해 고안된 random 탐색법과 조합된 random tabu 탐색법으로 최적결합계수를 구하는 학습알고리즘으로, 국소적 최적해에 수렴하는 것을 방지하고, 수렴정도를 개선하는 새로운 방법을 이용하여 회전기계의 이상진동진단에 적용가능성을 검토하고 오차역전파법에 의한 진단결과와 비교검토한다.

• 소음진동
• /
• 제8권4호
• /
• pp.623-631
• /
• 1998

The free vibration analyses of the isotropic and composite(CFRP, GFRP) rectangular plates with point supports at the free edge and middle position are performed. The natural frequencies and nodal patterns of plates with point supports are experimentally determined by impact testing using an impact hammer. To compare and verify these experimental results, the finite element analysis is also carried out. The effect of the point support position, the number of point supports, and the anisotropic parameters on the natural frequencies and nodal patterns of cantilevered rectangular plates are investigated.