• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.63-71
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• 2024

Through the development of construction technology, various construction projects such as redevelopment projects, undergrounding of roads, expansion of subways, and metro railways are being carried out. However, this has led to an increase in the number of construction projects in existing urban centers and neighborhoods, resulting in an increase in the number of damages and disputes between neighboring buildings and residents, as well as an increase in safety accidents due to the aging of existing buildings. In this study, digital data was applied to a graphics program to objectify the progress of cracks by comparing the creation of cracks and the increase in length and width through photographic images and presenting the degree of cracks numerically. Through the application of the program, the error caused by the subjective judgment of crack change, which was mentioned as a shortcoming of the existing field survey, was solved. It is expected that the program can be used universally in the building diagnosis process by improving its reliability if supplemented and improved in the process of use. As a follow-up study, it is necessary to apply the extraction algorithm of the digital graphic data program to calculate the length and width of the crack by itself without human intervention in the preprocessing work and to check the overall change of the building.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.709-714
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• 2017

Structures like bridges or buildings need to be checked continuously to diagnose their safety. However, it is extremely difficult for the people who access such structures to check all areas directly. To overcome this problem, there is a lot of active research into structural health monitoring (SHM) with wireless sensor nodes (WSNs). In this paper, for more accurate checking of SHM with WSNs, we experimentally compare and evaluate the performance of Xenomai, which provides real-time processing under the traditional Linux kernel. For this purpose, we patch Xenomai into the traditional Linux kernel of a commercial embedded board, Raspberry Pi, and implement a task that periodically reads vibration data of the z-axis from an accelerometer in order to analyze the natural frequency of cantilever beams. Reading the data from the traditional Linux kernel with the same method, we analyze the natural frequency of the cantilever beams using Smart Office Analyzer. Finally, to review the validity of Xenomai for WSNs, we obtain vibration data on the z-axis from the accelerometer via wired network and compared and analyzed them the same way.

• 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 Korea institute for structural maintenance and inspection
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• v.21 no.2
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• pp.87-94
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• 2017

In the nuclear power plant, the steel or polymer liner plates are adopted to prohibit the inner concrete surface from contacting with gas or liquid materials. If there is an accident, the plate may be damaged, and, in this case, concrete shall have the final responsibility to safety requirements. In this paper, an experimental research was carried out to investigate the effects of construction joint and wet and loading conditions on the permeability of concrete. The test results showed that, under a construction joint in the wet condition, leakage of gas pressure has been started from $1kg/cm^2$. However, when there are no construction joints, it is initiated from $2kg/cm^2$. In addition, under the air dried and unloading condition, regardless of with or without the presence of the construction joint, since the gas passage that exist in concrete is constant, leakage has a constant tendency to increase. Finally, under the loading condition, as described in Reference 1, since leakage is inversely proportional to the thickness of the wall, and, considering the wall thickness of the actual plant, it is found that there will not be no problem in the sealing of the gas.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.60-67
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• 2021

According to the 「Guidelines of Structural Design for Piloti Building」 of the Ministry of Land, Infrastructure and Transport (2018), the natural period of middle and low rise building of upper-walled lower frame type, such as the domestic multiplex house in piloti style, is suggested for safety to apply the existing code formula of the wall structure. However, the current code formula of the wall structure was provided based on actual measurement of high-rise wall-type structures that mainly exhibit bending behavior. So it is considered that it is not suitable for a piloti-type house with four stories or less, where the wall behaves in shear. See also Park et al. (2000) confirmed that the effect of the lower frame part is greater than that of the upper wall part in the natural period of complex structures with 10 or more floors through analytical studies. Therefore, in this study, in order to examine the effect of the lower frame on the natural period of the middle and low-rise piloti structure, the estimation of natural period by the finite element analysis, approximation formula and ccurrent code formula was performed for the target structures with the shear and flexural stiffness of the upper wall and the shear stiffness of the lower frame as variables. As result, it was found that the change in the shear stiffness of the lower frame had a greater effect on the natural period of the whole building than the change in the bending or shear stiffness of the upper wall.

• Korean Journal of Construction Engineering and Management
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• v.20 no.2
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• pp.113-118
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• 2019

Recently, the maintenance concept of infrastructure has been changed from the stability management of the structure determined by the safety inspection of the existing facilities to the asset management related to evaluating and managing the performance of the facilities. For management of the property of the facilities, it is necessary to efficiently classify their information for the maintenance and service level of the facilities and to manage them. In the case of power plant facility, especially, it is a complex structure, which is constructed in a various component and detail. In this study, therefore, the components of power plant facility were classified into facilities, spaces, parts, and elements considering the type of integrated construction classification system in Korea. To reflect the deterioration rate of the facility in accordance with environmental conditions such as airborne salt and humidity etc., it was classified by adding direction, interior, and exterior condition of each component not to be considered in the existing classification system for its effective and systematic maintenance, since it is generally located in the coastal area due to the operation of the power generation structure. The classification system developed in this study can be used as fundamental data for development of the computer system for asset management of power plant facility.