• Journal of the Korean Geotechnical Society
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• v.38 no.2
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• pp.29-38
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• 2022

The friction anisotropy of shear resistance can be selectively used in geo-structures. For example, larger axially loaded deep foundation, soil nails, and tiebacks increase load carrying capacity due to induced large shear resistance while pile penetration and soil sampling produce minimal shear resistance. Previous studies confirmed direction-dependent shear resistance induced by interface between soil and surface asperity of plate inspired by geometrical shape of snake scale. The aim of this paper is to quantitatively evaluate interface friction angle with different surface asperities. Using the modified direct shear test, a total of 51 cases, which sand are prepared at the relative density of 40%, are conduced including 9 plates, two shear direction (shearing direction against the height of surface asperity is increased or decreased during shearing test), and three initial vertical stress (100 kPa, 200 kPa, 300 kPa). Experimental results show that shear stress is increased with higher height of surface asperity, shorter length of surface asperity, and the shearing direction that the height of surface asperity increases. Also, interface friction angle is decreased with larger surface asperity ratio, and shearing direction with increasing height of surface asperity produces larger interface friction angle regardless of the surface asperity ratio.

• Korean Security Journal
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• no.22
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• pp.113-144
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• 2010

Bioterrorism is becoming more attractive to terrorist groups owing to the dramatic increase in the utility and lethality of biological weapons in line with today's cutting-edge biological science and technology. The Republic of Korea is facing both internal and external terrorist threats, as well as the possible biological warfare by North Korea. Therefore, it is essential to establish an effective bioterrorism response system in the ROK. In order to come up with the adequate response system for the ROK, an in-depth study has been conducted on the current bioterrorism response system of the U.S. whose preparedness is considered relatively adamant. As a result, the following facts have been found: (1)the legislation with regard to bioterrorism has been established or amended according to the current situation in the U.S., (2)the counter terrorism activities have been integrated with the Department of the Homeland Security as the central agency in order to maximize the national CT capacity, (3)Specific procedures and instructions to cope with bioterrorism have been made into manuals so as to enhance the working-level response capabilities. Next, the analysis on the ROK's bioterrorism response system has been performed in various categories, including the legislation system, task role distribution, cooperative relations, and resource application. It turned out that the ROK's legislation basis is relatively weak and it lacks the apparatus to integrate the bioterrorism response activities on the national level. The shortage of the adequate response facilities and resources, as well as the poor management of manpower have also emerged as problems that hinder the effective CT implementations. Through an analytical and comparative study of the U.S. and the ROK systems, this paper presents several ways to ameliorate improve the current system in the ROK as follows: (1)establish the anti-terrorism law, which would be the basic legal basis for the bioterrorism-related matters; and make revisions to the disaster-related legislation, relevant to bioterrorism response activities, (2)establish an integrated body that has a powerful authority to coordinate the relevant CT agencies; and converge the decentralized functions to maximize the overall response capacity, (3)install the laboratories with a high biosafety level and secure enough of the strategic medical stock-pile, (4)enhance the ability of the inexperienced response personnel by providing with a manual that has detailed instructions.