• The Journal of the Acoustical Society of Korea
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• v.16 no.5
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• pp.60-67
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• 1997

the famous King Song-dok Bell which was cast in A.D. 771, during Silla dynasty has significant xize of concave cavity which acts as Helmholtz resonator on the ground. To see the effect of this cavity and the bell's internal acoustic cavity on radiating sound of bell, three dimensional measurement of internal sound field was performed. In this paper, the dtail measurement procedure and results are carefully addressed. The effect of the cavity on the radiating sound of bell is investigated using simple and physically representative model. A new size of cavity is proposed.

• 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.

• The Journal of the Acoustical Society of Korea
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• v.16 no.6
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• pp.19-24
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• 1997

The acoustic characteristics of the sound-pipe of King Song-Dok bell, which is located on the top, are investigated by experiment and simulation. The experimental results;reflection coefficient, and radiation impedance, demonstrate that the sound-pipe is capable of radiating high frequency(above 300Hz) sound; it behave as damper. It is also found that a waveguide model well presens the acoustic characteristics of the sound-pipe.

• 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.

• 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.

• The Journal of the Acoustical Society of Korea
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• v.30 no.4
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• pp.223-230
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• 2011

Korean bell is hung with some air gap between the bell bottom and the ground. In addition, it has a peculiar acoustic element, so called resonance cavity below the bell. A proper design of the air gap and cavity size dramatically amplifies the bell sound by resonance effect. Bell interior cavity, air gap and resonance cavity consist of an acoustic cavity system. When the acoustic cavity frequency coincides with the natural frequency of the bell body, the frequency component is significantly amplified. On the Sacred Bell of the Great King Seongdeok, this study proposes a resonance condition of the cavity system considering air gap effect for the first time. With the exact dimension of the bell, boundary element analysis is performed using SYSNOISE. Finally, this study reveals how the temperature in season influences the resonance condition and proposes a concept of variable type resonance cavity. By using the variable type resonance cavity, the cavity size is controlled on site and exact resonance is available regardless of temperature difference in season.

• The Journal of the Acoustical Society of Korea
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• v.36 no.3
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• pp.194-201
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• 2017

Silla Great Bell was made to reproduce King Seongdeok Divine Bell and it was restored to have the same structure and patterns. The most difficult problem was to reproduce the magnificent striking sound and dynamic hum tone with strong beat like in King Seongdeok Divine Bell. Especially, beating sound is attributed to the uncontrollable asymmetry occurring in the casting process, so it can not be predicted or controlled before casting. In this study, we introduce the method and process to make Silla Great Bell have a strong beat with a proper period. Position conditions of mode pairs and striking point for a strong beat were identified. Bell thickness was locally decreased to make proper period of beat. The process was performed according to the simulation result of an equivalent bell model. As a result, the original weak and long beat was made to a strong beat with a proper period.

• The Journal of the Acoustical Society of Korea
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• v.16 no.4
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• pp.94-100
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• 1997

In order to investigate the radiation of sound from the King Song-Duk bell, we measured the sound pressure around the bell at every 30$^{\circ}$ using a microphone line array which was composed of 30 microphones separated by 15cm;total number of measurement point was 360. The sound field was estimated by using cylindrical acoustic holography. The spectrum of measured sound pressure demonstrates that it is almost like white noise in the very beginning, but in 10 seconds two close frequency components(64.06Hz, 64.38Hz) remain and make a famous beating. This beating sound is often believed to make unique sound of the King Song-Duk bell. The mode shapes of that frequency components are the same except that one is rotated by 45$^{\circ}$ from the other. This phenomenon occurs at the other pairs of components are the same except ones in very high frequency range where the mode shapes are rather complex.

• 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.

• Journal of Korean Society for Geospatial Information Science
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• v.6 no.1 s.11
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• pp.65-74
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• 1998

The acquisition and analysis system of accurate geometrical digital data is very important in side of maintaining the traditional culture for the preservation of cultural properties. This study is on the construction and shape analysis of precise digital data to manage more successfuly using the CRP method and 3D Mono Mobile System. Also this study could acquisite 3D geometrical digital data, make such various space analysis and section, projection, and calculation of bias, area and volume and modeling by rendering technique on the misterious bell of great king of SungDuck, one of the greatest bells in periods of TongIl Silla. So, We suggest utilization of image analysis method to safety diagnosis for the maintenance of cultural properties, archeological and artistic research.