• Korean Security Journal
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• no.36
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• pp.293-316
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• 2013

Today's high-rise buildings are increasing concern about the safety and evacuation of people related to the fire and threat from outside. Terrorism breaking out in high-rise buildings, a symbol of the national economy results in a number of casualties, economic loss, social fear and damage to national status. That's why high-rise building has also emerged as a target of major terrorist attacks, compared to other types of buildings. We have 54 high-rise buildings in 15 regions over the country. The Ministry of Land, Infrastructure and Transport and Seoul Metropolitan Government have offered the guidelines to prevent terrorist attacks toward high-rise buildings. Since the 9/11 terrorist attacks, the U.S. Federal Emergency Management Agency (FEMA) has developed and taken advantage of the Risk Management Manual Series. According to this manual, pre-assessment is conducted for the prevention of terrorism and particularly in FEMA 455, risk of the surrounding areas, vulnerability, possibility from terrorist attacks are checked. After the check, experts classify the risk of terrorist attacks toward the high-rise buildings and according to the risk classification, architects, security experts and structure engineers can carry out terrorism prevention program for high-rise buildings. The U.K. NaCTSO has also offered the terrorism prevention guidelines. Therefore, the Ministry of Land, Infrastructure and Transport and Seoul Metropolitan Government should make more concrete guidelines for high-rise buildings such as what U.S. FEMA and U.K. NaCTSO implement, including prior evaluation technique for terrorism risk.

• Journal of the Korean Geotechnical Society
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• v.36 no.10
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• pp.5-19
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• 2020

With increasing demand for offshore structures, the demand for temporary structures to help the offshore construction work has increased. A cofferdam is a temporary barrier to stop the inflow of water in the construction site and allows working in the dry condition when the construction is done within the water. However, it is a major cause of construction delays and increased costs because additional works are required to block the water inflow. Recently, in order to overcome the limitations of the conventional cofferdam methods and to increase economic efficiency, a large-diameter steel cofferdam method has been proposed which can be installed quickly in the seabed by using the suction pressure. In this circular steel cofferdam method, the top side of the cofferdam including the top-lid is always exposed above the sea level in order to use it as a water barrier, unlike the conventional suction bucket foundation. After installation, the top-lid of the cofferdam is removed and the water filled inside the cofferdam is discharged to make the interior dry condition. In this study, the circular steel cofferdam with a 5 m inner diameter was fabricated and the installation tests were conducted at the Saemaguem test site. During the experiment, variation of suction pressure, leakage between connections, structure deformation, and inclination of the steel cofferdam were measured and post-analyzed. This study verified the new circular steel cofferdam method and confirmed that the suction installation method can be successfully used for various purposes on offshore structures.

• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.73-88
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• 2015

Due to the cases of recent global warming and unusual weather etc., large-scale natural disasters such as typhoons, floods, snow damage occur frequently across the continents such as Southeast Asia and North America, South America etc. and risks of earthquakes and tsunami are also increasing gradually in Korea which has been regarded as a safe zone and disaster types are also being diversified such as typhoons, floods, heat waves, heavy snow and damage scale is also enlarged. In addition, due to geographical characteristics or lack of infrastructure, disasters tended to occur intensively around a specific region or city in the past but disasters occur throughout the country in recent years so preparation for disaster prevention has emerged as an urgent challenge issue. Therefore, considering that the plan of obtaining the effective feedback function of disaster Information is very important in the proactive and software aspects for disaster reduction, this paper analyzed this three aspects of contents, procedural and contextual aspects and proposed the plan. First, in the content aspect, building disaster prevention information communication Infrastructure, building urban and regional disaster prevention system, obtaining concurrency and sharing of information and second, in the procedural aspect, active utilization of ICT(Information and Communication Technology) of the prevention stage, disaster prevention information collection and analysis reinforcement of the preparation stage, improvement of decision-making structure and field command system of the response stage, recovery system related information promotion of the recovery stage were proposed as alternatives and finally, in the contextual aspect, if disaster prevention information is effectively managed through maintenance of disaster prevention information related systems, obtaining domainality by disaster prevention work, improvement of the ability to judge the situation, obtaining comprehensive and feedback function etc, it is considered to significantly contribute to reducing natural disasters.

• Ecology and Resilient Infrastructure
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• v.5 no.1
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• pp.25-34
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• 2018

This study presents prediction and historical analysis of the long-term bed elevation change in the Mankyung-gang River. The study area is a 25 km long reach including middle and lower courses of the Mankyung-gang River. HEC-RAS program was used for numerical predictions, and values of roughness coefficients were calibrated. Then, predictions were made in the two periods, seven years from 1986 to 1993 and twelve years from 1993 to 2005. Simulation results were compared with two sets of measured data for bed elevations. Four sediment transport formulas, namely MPM's, Toffaleti's, MPM-Toffaleti's, and Yang's formula, were tested. Simulation results showed that none of the four sediment transport formulas predicted the bed elevation change in the period of 1986 - 1993. This is related to the fact that dredging work was performed in the upstream reach in the period of 1986 - 1993, and sediment was deposited in this part severely later. However, it was found that MPM-Toffaleti's formula predicted properly the bed elevation change for the period of 1993 - 2005.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.183-191
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• 2015

Studies on the environment-friendly and permanent low energy saving measure are and will continue to be an eternal challenge. However, the demand is high for the technologies that can save energy significantly in everyday life that produce tangible benefits for the users by applying saving factors and that anyone can access easily when it comes the related procedure. Government policies related to the improvement of energy effect in the existing building structure are characterized by complex procedure. Moreover, cost required and reliability issue emerge when request is made to an expert. Accordingly, this study seeks to present energy improvement plan that can be utilized simply and conveniently at any place, any time by enabling customized design according to individual taste by enabling energy change amount and grade prediction when the users select only the part that they want to replace by using a simple program.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.227-235
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• 2019

This study monitored Daecheong 1-bo, Daecheong-stream, which carried out the project in 2014, from 2015 to 2016. The technology applied to the stream was evaluated using Periphytic Algae to check contamination indicators and ecological health of the area with an integral river-bed protection using non-toxic materials. The water quality of the monitoring section was confirmed to be above the river environment standard (II), and it was confirmed that the Saproxenic taxa of the river bed protection were higher than the upper and downstream sections. The TDI, which is an index of attachment algae, was shown in the average 51.03 and 52.15 for the pilot project sections in 2015 and 2016, confirming that the index is of the "normal" grade. This is the other sections in the upstream and downstream sections showed higher than "bad", which is thought to have a positive effect on the habitat of the river ecosystem components, especially the microbial population in river bed protection.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.243-249
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• 2019

The purpose of this study is to analyze the reflectance of bed materials according to changes in the water level using a drone-based hyperspectral sensor. For this purpose, we took hyperspectral images of bed materials such as soil, gravel, cobble, reed, and vegetation to compare and analyze the spectral data of each material. To adjust the water level, we constructed an experimental channel to control the discharge and installed the bed materials within the channel. In this study, we configured 3 cases according to the water level (0.0 m, 0.3 m, 0.6 m). After the imaging process, we used the mean value of 10 points for each bed material as analytical data. According to the analysis, each material showed a similar reflectance by wavelength and the intrinsic reflectance characteristics of each material were shown in the visible and near-infrared region. Also, the deeper the water level, the lower the peak reflectance in the visible and near-infrared region, and the rate of decrease differed depending on the bed material. We expect the intrinsic properties of these bed materials to be used as basic research data to evaluate river environments in the future.

• Journal of the Korean Geotechnical Society
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• v.36 no.8
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• pp.61-72
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• 2020

It is generally considered that differences of axial stiffness between exiting pile and reinforcing pile affect the load distribution ratio during vertical extension remodeling. But there are few cases to verify the effect of stiffness by field load test on load distribution ratio in Korea. In this paper, a series of load tests for micropiles were carried out to evaluate the effect of axial stiffness on the load distribution ratio. First, different types of micropiles were constructed so that conventional micropiles simulated existing piles and waveform micropiles simulated reinforcing piles. Secondly, load tests were performed to evaluate the stiffness of each piles. After then, the raft was installed to make a piled raft system and load tests were applied on foundation to verify the effect of axial stiffness on the load distribution ratio. The experimental results show that the stiffness of waveform micropiles were 2.5 times larger than that of conventional micropiles, and the load distribution ratio between existing and reinforcing piles was increased according to axial stiffness of piles.

• Journal of the Economic Geographical Society of Korea
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• v.7 no.1
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• pp.1-27
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• 2004

In this paper we attempt to explore the institutional and clutural milieu of high-tech venture business cluster in Daegu City and provide policy implications for creating sustainable high-tech venture businesses cluster. Although since 1998 the Korean government has made explicitly a great deal of efforts to help attract and create high-tech new start-ups in non-capital cities such as the support of business incubating centers and the establishment of real service centres, it reveals that such policies are not so successful in creating a sustainable venture ecology. One of the most critical resions is that such policies are centred simply on building physical infrastructure such as incubating space and service centre with less concern with promoting venture business cluster reflecting cultural and institutional specificities in a given region. In this respect we argue that the focus of industrial policies to support promoting high-tech venture business clusters in non-capital cities urgently need to move towards to make it for firms to encourage entrepreneurship driving innovation and to create social capital incucing trust and networks amongst firms, universities, public &privite supporting agencies, together with the building up of physical infrastructure the existing policies have done.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.225-238
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• 2018

In this paper, to investigate the influence of installation damage, a variety of full-scale field installation tests with 15 geosynthetics reinforcements and fill materials of various grain size distribution have been performed. The full-scale field installation test was conducted with reference to the FHWA (2009) guidelines. The tensile strength tests were performed by sampling up to 20 specimens randomly from the excavated geosynthetics reinforcements after compaction of fill material, and the degree of decrease in tensile strength of reinforcements due to compaction was analyzed based on the experiment results. It was found that the degree of tensile strength reduction of geosynthetics reinforcements due to the compaction of fill material is greatly influenced by the type of reinforcement and the maximum diameter of fill material. In addition, it was found that the strength reduction ratio of PET geogrid (PVC coating) with relatively small stiffness was greatest, and that the larger the maximum grain size of the fill material, the greater the strength reduction ratio. And also, a more reasonable evaluation method for the installation damage reduction factor of geosynthetics reinforcements is proposed based on the results of full-scale field installation tests in present study and the existing test results.