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Han, Shin-In;Lee, Jong-Sub;Lee, Yong-Jun;Nam, Seok-Woo;Lee, In-Mo
- Journal of Korean Tunnelling and Underground Space Association
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- v.9 no.1
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- pp.75-82
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- 2007
As one of the main support systems, rock bolts play a crucial role in the reinforcement of tunnels. Numerical and experimental studies using a transmission method of ultrasonic guided waves are performed to evaluate the integrity of rock bolts encapsulated by grouting paste. Numerical simulations using "DISPERSE" are carried out for the selection of the optimal experimental setup, i.e. non-destructive testing (NDT) system of the rock bolt. Based on results of the numerical simulation, the calculated frequency range for NDT testing is between 20kHz and 70kHz with the first longitudinal L(1) mode. Laboratory transmission tests are performed by attaching the piezo electric sensor at the tip of the rock bolt before embedding. Both of analytical and experimental results show that the amplitude of signals as well as the wave velocity increases with increase in the defect ratio of grouting paste. The defect in grouting paste means that the space around the rock bolt is not fully filled with the grouting paste. Experimental results also show that the increase of the wave velocity is more sensitive to the defect ratio increase than that of the amplitude. This study demonstrates that the transmission technique of ultrasonic guided waves may be a valuable tool in the evaluation of the rock bolt integrity.
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Yoon, Dae-Geun;Nam, Tae-Woo
- Journal of Korean Society of Archives and Records Management
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- v.11 no.2
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- pp.143-163
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- 2011
The National Assembly of R.O.K. has established and developed parliamentary democratic system up to now since the Constitutional Assembly in 1948. However, in order to establish and develop the management system that reflects an inherent character of the parliamentary minutes, lots of things are yet to be improved in institutional and operational aspects. This study aimed to propose the proper management system and improvement methods of the parliamentary minutes by comparing & analyzing minutes management cases of major foreign countries having a long history and the minutes of the National Assembly of R.O.K. First, it is necessary to make in-depth discussions about methods for reorganizing administrative system for the efficient production and management of the parliamentary minutes. Second, for the guarantee of the parliamentary minutes, systematical management based on laws is needed. The various types and value and characteristics involved in the minutes of the National Assembly can be said to start with a congressman, a representative the Nation and a member of the National Assembly. Accordingly, the minutes of the National Assembly produced from parliamentary members who were elected by the people must be freely utilized by the people.
https://doi.org/10.14404/JKSARM.2011.11.2.143 인용 PDF