• Journal of Korean Association for Spatial Structures
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• v.7 no.2 s.24
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• pp.105-114
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• 2007

Large span spaces have been widely used for various purposes including sports events in other countries. Due to increasing demands on multi-purpose use of such spaces, recently built large span sport facilities such dome stadiums have been required to accommodate sport events as well as performing events. Also, retractable ceilings and/or walls were generally adopted in those spaces for providing various event conditions. It seems obvious that the openings between diffuse fields and free field may cause difficulties in the acoustic design of such spaces In the present work, the acoustic characteristics of non-diffuse field has been investigated using 1/10 acoustic scale models. It was found that RTs at low- and mid-frequencies decayed faster than those at high-frequencies as the percentage of opening area increased. The decay rate of RTs at high frequencies were not influenced by increasing the area of an opening. Also high dependence of EDT on the percentage of opening area was observed at all frequency range. D50 was not improved by increasing the area of an opening up to 12.5% and then sharply increased. The application of Schroeder integration to evaluate the reverberation charateristics of coupled spaces may not be proper, since non-exponential decay process with double or triple decays of those spaces can not be properly defined. EDT seems more appropriate to predict reverberation at the early acoustic design stage of acoustically coupled spaces.

• Journal of the Korean Institute of Educational Facilities
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• v.25 no.6
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• pp.11-20
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• 2018

In order to figure out the usability of various timber structures in the educational facility, the recent timber structure examples published in the Japanese architectural magazine, 'ShinKenchiku' over the past five years were surveyed. As the results, timber structures were presented in many cases of nursery schools and kindergartens overwhelmingly, and they also used in various school buildings, university facilities, and the roof structure of the school's gymnasium, with intention of having the differentiated design and space features. The examples show that span 6 to 10m is generally used with flexure structure system and flexure+compression structure system added the strut as compression members. In addition concerning stability, it was founded that the struts have an stability effect in the flexure+compression structure system, and flexure structure system examples using semi-rigid joints have open spaces liberally in two-way direction for about 9m span. For large spaces structures with span of 15~20m or more, the various structural system such as suspension structure, truss, flexure+compression, etc. was designed to overcome the material limitations of timbers and to make an design effect in structure system.

• Journal of Korean Association for Spatial Structures
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• v.11 no.1
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• pp.67-75
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• 2011

The present work investigate the effect of sound reinforcement systems on the acoustics of a large dome stadium using a computer simulation. The acoustics of a dome stadium was predicted analyzed by varying room absorption, as well as the configuration of speakers including their directivity, installed height, and numbers. It was found that both D50 and RASTI were improved by increasing room absorption. Larger EDTs were observed according to the increase of room absorption at mid and high frequencies. On the other hand, RT did not show any significant correlation with the changes in room absorption, which might be the effect of a forced linear fitting for non -linear energy decay process. With respect to the speaker configuration, the speech intelligibility of a sound reforcement system installed at higher placed more relied upon their directivity rather than room absorption, Also, lower placing of speakers was found to be effective in decreasing RTs regardless of room absorption.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.596-605
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• 2005

The cable dome, proposed by Geiger after developing Fuller's idea of tensegrity and improved by Levy, is a new type of large span space structures. In this paper, formulations of the initial forces distribution in members of two main systems of cable dome, which are Geiger dome and Levy dome, are presented. By analyzing the static performance of Levy dome and the variation of internal forces in members of the structure, four groups of design parameters in cable dome structure are represented in terms of: (1) the numbers of rings and the spaces between the rings; (2) the slopes of ridge cables; (3) the lengths of struts; (4) the initial force in one member of the structure.

• Journal of Korean Association for Spatial Structures
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• v.7 no.5
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• pp.75-82
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• 2007

The present work measured and analyzed changes in the acoustics of a sound field which has a retractable ceiling. An 1/20 scale model of an openable space was built and measurement was carried out by varying the opened area of a ceiling. The most widely used room acoustic and design parameters, RT, EDT, and D50 were investigated. The results suggest that the use of RT as an acoustic design parameter may not be proper in an openable space and further it is likely to mislead the initial acoustic design of such spaces. It is mainly due to the characteristics of RT in which non-exponential decay processes are linearly fitted. Early decay times were found to be decreased in proportion to increaing the ratio of opened area. D50, an index of speech intelligibility, was effectively shows the influence of openings on the acoustics. It is also found that EDT and D50 at the seats, not directly exposed to the opened part of a ceiling, were almost linearly decreased in proportion to the ratio of opened area, while little influence was found for the opening ratio larger than 40% at the directly exposed seats to the opened part of a ceiling.