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이중혁(Joonghyeok Lee),이호진(Hojin Lee),박인석(Inseok Park),김석현(Seockhyun Kim) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.10
The sidewall of the HEMU-400x consists of two parts. One is the multi-layered structure including aluminium extruded panel and the other is the double glazed window. When the train runs in a tunnel, the equivalent sound insulation performance of the side wall significantly influences the internal noise levels. In aspect of the sound insulation strategy, it is important to make two parts have similar performance. In this study, the intensity sound transmission loss (ITL) is measured on the specimens of the two parts. Mass law deviation (MLD) is considered in order to compare the sound insulation performance of the two parts in respect of the weight. Contribution of each part to the sound insulation is analyzed and the sound insulation strategy is investigated to reduce the interior noise.
이중혁(Joong-hyeok Lee),김석현(Seock-hyun Kim) 한국소음진동공학회 2013 한국소음진동공학회 학술대회논문집 Vol.2013 No.4
This study proposes an equivalent bell model for the Sacred Bell of the Great King Seongdeok. An equivalent bell model has the modal property of the real bell and it consists of an axi-symmetric bell body and a point mass. The 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 can be controlled by decreasing the thickness of local area. This study aims at showing a beat period control method for a large bell having the similar size to the Sacred Bell of the Great King Seongdeok.
이중혁(Junghyeok Lee),김석현(Seockhyun Kim) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.5
Aluminum extruded panel used in a high speed train shows high stiffness, however, its sound insulation performance is remarkably decreased by local resonance phenomena. In this paper, improvement strategy of the sound insulation performance is proposed for the floor extruded panel used in HEMU-400x, 400km/h class next generation high speed train under development, and the improvement effect is verified by experiment. Aluminum extruded panel specimen for the floor is manufactured and urethane foam is installed in the core of the panel. Based on ASTM E2249-02, intensity transmission loss is measured and the improvement effect in local resonance frequency band is verified. Finally, improvement effect of the sound insulation performance is estimated on the layered floor structure including the foamed aluminum panel.