• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.7
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• pp.534-541
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• 2002

Vibration and sound characteristics of King Song-Dok Bell are ivesigated. Natural frequencies. vibration modes and beat period of the bell are precisely measured. The effect of striking position and the position of nodal lines on the beat characteristics is examined. It is first found that the beat characteristics are quote different according to the position on the bell surface and clear beat is periodically generated on the circumference. It turns out that in King Song-Dok Bell, Dangjwa(the present striking position) is located at the position which makes a beat in the first vibration mode, as welt as it produces very clear beat In the second vibration mode.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1161-1168
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• 2002

Vibration and sound characteristics of King Song-Dok Bell are measured and the modal property is investigated. The effect of striking position and modal property on the beat characteristics is examined. It is first found that the beat characteristics are quite different according to the position on the bell surface and clear beat is periodically generated on the circumference. It turns out that in King Song-Dok Bell, striking Dangjwa(the present striking position) makes a beat in the first vibration mode, as well as it produces very clear beat in the second vibration mode.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1169-1176
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• 2002

Analytical model of beat response is derived on a slightly asymmetric ring and is veryfied by experiment. The asymmetric ring is a simplified model used to explain the beat property of a Korean bell. The asymmetric ring has mode pair having slight frequency difference in each radial mode. Each mode pair produces beat phenomenon by the interaction of the two close frequency components. Based on the analytical model, beat maps are first proposed and characteristics of beat on the circumference are detaily explained.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.498-504
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• 2002

Vibration beat phenomenon is theoretically investigated on a slightly asymmetric cylindrical shell, which is a simplified model of Korean bell. Mode pairs of the slightly asymmetric shell are obtained by receptance analysis and impulse response of the shell is derived using modal expansion and Laplace transform. Based on the impulse response model, beat mapping method is proposed to explain the reason that the beat of a bell vibration shows periodic distribution on the circumference. Beat characteristics of King Song-Dok Bell are explained in detail using the beat map and the measured modal data.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.8
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• pp.626-636
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• 2003

The beat distribution property of the King Seong-deok Divine Bell is investigated by experiment and analysis. The beat map method is proposed to explain the beat distribution property on the circumference of the bell. For the analytical investigation, an analytical model of the vibration beat is derived on a slightly asymmetric shell of revolution by using the modal expansion method. In the analytical method, the beat map can be drawn only if the modal parameters of the bell are obtained. The analytical beat model is applied to draw the beat map of the King Seong-deok Divine Bell. The validity of the analytical method is verified by comparing the analytical beat maps with the experimental results. This paper proposes a visualization method of the beat and theoretically identifies the reason why the clear and unclear beats repeat periodically along the circumference of the bell and how the striking position influences the beat distribution property.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.359-360
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• 2009

In this study, we propose a practical method to improve the clarity and the period of the beat in a Korean bell. Proper beating in vibration and sound is very important feature in Korean bell. An equivalent ring theory is applied and finite element analysis is performed to determine the condition of the asymmetry of the bell. The clearity and the period of the beat are improved by attaching a counter mass or decreasing local thickness. This paper shows that the improved the attaching a counter mass or decreasing local thickness. This paper of the beat are improved by attaching a counter mass or decreasing local thickness. This paper shows that the amount and position of the local variation for the required beat condition can be predicted by using the equivalent model, The predicted results are verified by the experiment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.516-519
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• 2012

This study proposes a method of an equivalent bell model in order to tune the beat period of a Korean bell. In a Korean bell having a slight asymmetry, each circumferential mode splits into a mode pair which has a slight difference in frequency, and the interaction of the mode pair makes a beat in vibration and sound. An equivalent bell model which consists of an axi-symmetric bell and an equivalent point mass, has the same mode property as in a real bell. The equivalent bell model is constructed by the finite element analysis based upon the theory of a revolutionary shell Using the equivalent bell model, the beat period is predicted when the bell thickness is locally decreased to improve the beat property. The predicted result is verified by experiment on a test bell. The proposed method is useful to save the time required for tuning the beat period of a large bell.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.929-932
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• 2012

Beat map shows the distribution property of the beating sound in the bell structure. Using the beat map, beat control and beat estimation are available. To draw the beat map, mode pair parameters of the bell are required. However, in case of large bell which is struck by a heavy wooden hammer, it is very difficult to measure the excitation force and to obtain the mode pair parameters. In this paper, we determined the mode pair parameters of the bell from the transmissibility between the roving signal and reference signal, using ODS(operational deflection shape) method. The mode pair data are input to the theoretical model of the beat response and beating waves are generated on the bell circumference. All the numerical and beat map drawing procedures are automatized using Matlab. Finally, the reliability of the beat map generated by the program is verified.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.353.1-353
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• 2002

Impulse response of a slightly asymmetric cylindrical shell is derived. Receptance method is applied to obtain the vibration mode and natural frequency of the slightly asymmetric cylindrical shell. Impulse response model is used to identify the vibration beat characteristics of King Song-Dok Bell. The theretical mode is compared and verified by the measured mode of King Song-Dok Bell. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.385-386
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• 2010