• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.568-571
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• 1997

The overall aim of this paper is to determine coupling loss factor using loss factor and structural loss factor. For this purpose, two kinds of loss factor were adopted. One is loss factor of each sub structure, another is structural loss factor based on the complex welded or assembled structure. Using these two parameters, it is possible to derive the coupling loss factor which represent characteristic condition of SEA theory. Coupling loss factor of conjunction in complex structure was expressed as power balance equation. The derived equation for a coupling loss factor has been simplified on the assumption of one directional power flow between two sub structures. Using these conditions, it is possible to find the coupling loss factor equation. The comparison between theory of power transmission on conjunction and above equation, show a good agreement in simple beam structure. To check the effectiveness of above equation, it was adopted rotary compressor. Rotary compressor has three main conjunctions between shell and internal vibration part. This equation was applied to find out the optimum welding point with respect to reduce the noise propagation. It shows the effective tool to evaluate the coupling loss factor in complex structure.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.5
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• pp.370-376
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• 2004

The overall aim of this paper is to determine coupling loss factor of welding point between shell and cylinder using loss factor and structural loss factor. For this purpose, two kinds of loss factor were adopted. One is loss factor of each sub structure, another is structural loss factor based on the complex welded or assembled structure. Using these two parameters, it ispossible to derive the coupling loss factor which represent characteristic condition of SEA theory. Coupling loss factor of conjunction in complex structure was expressed as power balance equation. The derived equation for a coupling loss factor has been simplified on the assumption of one way (uni-directional) power flow between multi-sub structures. Using these conditions, it is possible to find the equation of coupling loss factor expressed as above two loss factors. To check the effectiveness of above equation, this paper used two-stage application. The first approach was application between simple cylinder and shell. The next was adopted rotary compressor. Rotary compressor has three main conjunctions between shell and internal vibration part. This equation was applied to find out the optimum welding point with respect to reduce the noise propagation. It shows the effective tool to evaluate the coupling loss factor in complex structure

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.969-972
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• 2003

The overall aim of this paper is to determine coupling loss factor of welding point between shell and cylinder using loss factor and structural loss factor. For this purpose, two kinds of loss factor were adopted. One is loss factor of each sub structure, another is structural loss factor based on the complex welded or assembled structure. Using these two parameters, it is possible to derive the coupling loss factor which represent characteristic condition of SEA theory. Coupling loss factor of conjunction in complex structure was expressed as power balance equation. The derived equation for a coupling loss factor has been simplified on the assumption of one way(nl- directional) power flow between multi-sub structures. Using these conditions, it is possible to find the equation of coupling loss factor expressed as above two loss factors. To check the effectiveness of above equation, this paper used two stage application. The first approach was application between simple cylinder and shell. The next was adopted rotary compressor. Rotary compressor has three main conjunctions between shell and internal vibration part. This equation was applied to find out the optimum welding Point with respect to reduce the noise propagation. It shows the effective tool to evaluate the coupling loss factor in complex structure

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.258-264
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• 2012

The overall aim of this paper is to determine coupling loss factor of welding point between shell and cylinder using loss factor and structural loss factor. For this purpose, two kinds of loss factor were adopted. One is loss factor of each sub structure, another is structural loss factor based on the complex welded or assembled structure. Using these two parameters, it is possible to derive the coupling loss factor which represents characteristic condition of SEA theory. Coupling loss factor of conjunction in complex structure was expressed as power balance equation. The derived equation for a coupling loss factor has been simplified on the assumption of one way (uni-directional) power flow between multi-sub structures. Using these conditions, it is possible to find the equation of coupling loss factor expressed as above two loss factors. To check the effectiveness of above equation, this paper used two-stage application. The first approach was application between simple cylinder and shell. The next was adopted rotary compressor. Rotary compressor has three main conjunctions between shell and internal vibration part. This equation was applied to find out the optimum welding point with respect to reduce the noise propagation. It shows the effective tool to evaluate the coupling loss factor in complex structure.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.359-364
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• 2002

Statistical energy method is widely used for the prediction of vibrational and acoustical behavior of complex structures, such as ship building and automobile in mid-, high frequency ranges. However. in order to convince this SEA result, it is important to verify estimated SEA parameters, e. g. modal density, energy in each subsystem, damping loss factor, coupling loss factor. with possible other method. For modal density parameter, the experimental estimations via Experimental Modal Analysis are checked with those from finite element method for both beam- plate and plate-plate cans. Loss factors are calculated by Lyon's simple method for the two subsystem. finally. modal experiments are carried out by varying the mass added on the junction of two subsystem for the purpose of investigating the influence on the coupling loss factor's behavior.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.797-801
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• 2003

The Statistical Energy Analysis is based on the power flow and the energy conservation between sub-systems, which enable the prediction of acoustic and structural vibration behavior in mid-high frequency ranges. This paper discusses the identification of SEA coupling loss factor parameters from experimental measurements of small reverberation chamber sound pressure levels and structural accelerations. As structural subsystems, steel plates with and without damping treatment are considered. Calculated CLFs were verified by both transmission loss values for air-borne CLF case and running SEA commercial software As a result, CLFs have shown a good agreement with those computed by software. Acoustical behavior of air-borne noise and structure-borne noise has been examined. which shows reasonable results, too.

• The Journal of the Acoustical Society of Korea
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• v.21 no.4E
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• pp.164-169
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• 2002

This paper proposes a hybrid method for vibration analysis in the medium to high frequency ranges using Power Flow Analysis (PFA) algorithm and Statistical Energy Analysis (SEA) coupling concepts. The main part of the developed method is the application of coupling loss factor (CLF) suggested in SEA to the power transmission, reflection coefficients in PI' A boundary conditions. The developed hybrid method shows very promising results with regard to the applications for the various damping loss factors in wide frequency ranges. And also this paper presents the applied results of Power Flow Finite Element Method (PFFEM) by forming the new joint element matrix with CLF to analyze the various plate structures in shape. The analytical results of automobile, complex plate structures show good agreement with those of PFFEM using the PFA coefficients.

• The Journal of the Acoustical Society of Korea
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• v.21 no.4
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• pp.164-164
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• 2002

This paper proposes a hybrid method for vibration analysis in the medium to high frequency ranges using Power Flow Analysis (PFA) algorithm and Statistical Energy Analysis (SEA) coupling concepts. The main part of the developed method is the application of coupling loss factor (CLF) suggested in SEA to the power transmission, reflection coefficients in PI' A boundary conditions. The developed hybrid method shows very promising results with regard to the applications for the various damping loss factors in wide frequency ranges. And also this paper presents the applied results of Power Flow Finite Element Method (PFFEM) by forming the new joint element matrix with CLF to analyze the various plate structures in shape. The analytical results of automobile, complex plate structures show good agreement with those of PFFEM using the PFA coefficients.

• Journal of KSNVE
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• v.11 no.2
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• pp.257-264
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• 2001

In this research, piezoelectric smart structures are applied for SEA(Statistical Energy Analysis), which is well known approach for high frequency analysis. A new input power measurement based on piezoelectric electrical power measurement is proposed and compared with the conventional method in SEA. As an example, a simple aluminum beam on which piezoelectric actuator is attached is considered. By measuring the electrical impedance and electrical current of the piezoelectric actuator, the electrical power given on the actuator is found and this is In turn converted into the mechanical energy. From the measured value of the stored energy of the beam, the Internal loss factor is calculated and this value shows a good agreement with that given by the conventional method as well as the theoretical value. To compare the coupling loss factor, L-shape beam system which consists of a aluminum beam subsystem and a steel beam subsystem coupled by three pin is taken as second example. The input power and stored energy of each subsystem are found by the proposed approach. The coupling loss factor found by the electrical input power obtained from the piezoelectric actuator exhibits similar trend to the value found by the conventional method as well as the theoretical value. In conclusion, the use of SEA for high frequency application of piezoelectric smart structures is Possible. Especially, the input power that is essential for SEA can be found accurately by measuring the electrical input power of the piezoelectric actuator.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.7
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• pp.1015-1020
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• 2018

The cavity resonator is one of the widely used components in the microwave applications. The unloaded Q, the resonant frequency, and the coupling factor are basic parameters of a cavity. A simple unloaded Q factor measurement procedure of a cavity is proposed in a lossy coupling. The equivalent circuit of a cavity with coupling loss at near the resonant frequency is presented. The coupling loss resistance was found by the measurement of a cavity impedance. The cavity impedance compensated coupling loss was redrawn on the Smith Chart. The loaded Q and coupling factor were obtained based on the compensated impedance locus and then the unloaded Q factor was calculated. To verify the proposed procedure, the cavity with lossless coupling was measured. The two measurement results in the lossy and lossless coupling agree well. The results confirm the proposed procedure is valid.