• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.469-472
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• 2006

Amount used of admixture fare is increasing for concrete economic efficiency and ability security. Security of economic efficiency and ability can expect by use of this admixture fare but is displaying a lot of problems on early age strength hold by hydrate delay relatively. Specially, in the case of construction site, concrete strength can speak that interrelation is high with mold removal of forms time. Therefore, is economical and need examination of plan that can secure robber within 3 days using admixture fare such as fly ash and blast furnace slage differential speech to secure function. In this study, adding liquid admixture within 1% of a binding agent quantity to examine these problem with physical characteristic after hardening ago specially, strength change at standard and air dry curing of observed change in priority. Air dried and water curing total strength enhancement effects appeared by thing which is in case of add test result liquid admixture by below 1% and strength deputy by passage of age could know is not big.

• Korean Security Journal
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• no.60
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• pp.33-61
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• 2019

It is quite difficult to actually prove the effectiveness of so-called target-hardening, one of the various strategies used to reduce crime, one of the serious problems in society recently. In particular, three to five minutes is often used as golden time for intruders to give up or stop, which is based on foreign and some indirect research cases in Korea, but there were no studies that more directly identified the average break-in operation time or the abandonment time based on the elapsed time when the shield hardware resists intruders. This study was the first of its kind in Korea to investigate and verify samples of 90 inmates of break-in burglars who were imprisoned in August 2018 by profiling the average criminal experience, education level, age, height and weight of typical Korean professional break-in thieves, and specific criminal methods, average break-in operation time, and the criteria for giving up if not breached. According to the analysis results, in the survey on the number of pre-invasion theft crimes by intruders, many of the respondents who participated in the survey were criminals of professional invasions, and by their physical characteristics, there was not much difference from ordinary adult men. Residential facilities were the highest in the world, followed by commercial and educational facilities. According to the survey on the types of facilities that committed intrusion into residential facilities, it was not safe to say that single-family housing accounted for the largest portion of single-family housing, multi-family housing, apartment high-rise (more than three stories), and apartment low-rise (more than one to three stories) among residential facilities, and that the ratio of apartment high-rise was higher than expected. Based on the average time required to break into a place for an intrusion crime, it is assumed that the psychological time worked in a place where the break-in was difficult, since the break-in was not performed while measuring the time of the break-in operation. In the case of time to give up a crime, more than half of the respondents said they would give up the crime even in less than four minutes, suggesting that a significant number of intrusive crimes can be prevented even if the facility has four minutes of intrusion resistance. This proves that most intruders will give up the break-in if the break-in resistance performance of the security facility is exercised for more than five minutes.

• Journal of Information Processing Systems
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• v.8 no.2
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• pp.347-358
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• 2012

Recently, security researches have been processed on the method to cover a broader range of hacking attacks at the low level in the perspective of hardware. This system security applies not only to individuals' computer systems but also to cloud environments. "Cloud" concerns operations on the web. Therefore it is exposed to a lot of risks and the security of its spaces where data is stored is vulnerable. Accordingly, in order to reduce threat factors to security, the TCG proposed a highly reliable platform based on a semiconductor-chip, the TPM. However, there have been no technologies up to date that enables a real-time visual monitoring of the security status of a PC that is operated based on the TPM. And the TPB has provided the function in a visual method to monitor system status and resources only for the system behavior of a single host. Therefore, this paper will propose a m-TMS (Mobile Trusted Monitoring System) that monitors the trusted state of a computing environment in which a TPM chip-based TPB is mounted and the current status of its system resources in a mobile device environment resulting from the development of network service technology. The m-TMS is provided to users so that system resources of CPU, RAM, and process, which are the monitoring objects in a computer system, may be monitored. Moreover, converting and detouring single entities like a PC or target addresses, which are attack pattern methods that pose a threat to the computer system security, are combined. The branch instruction trace function is monitored using a BiT Profiling tool through which processes attacked or those suspected of being attacked may be traced, thereby enabling users to actively respond.

• Steel and Composite Structures
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• v.52 no.3
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• pp.357-376
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• 2024

In this paper, weakly bonded ultra-high-strength steel bars (UHSS) were used as longitudinal reinforcement in recycled aggregate concrete shear walls to achieve resilient performance. The study evaluated the repairability and hysteresis performance of shear walls before and after retrofitting. Quasi-static tests were performed on recycled aggregate concrete (RAC) and steel fiber reinforced recycled aggregate concrete (FRAC) shear walls to investigate the reparability of resilient shear walls when loaded to 1% drift ratio. Results showed that shear walls exhibited drift-hardening properties. The maximum residual drift ratio and residual crack width at 1% drift ratio were 0.107% and 0.01mm, respectively, which were within the repairable limits. Subsequently, shear walls were retrofitted with bonded X-shaped CFRP strips and steel plates wrapped at the bottom and retested. Except for a slight reduction in initial stiffness, earthquake-damaged resilient shear walls retrofitted with a composite method still had satisfactory hysteresis performance. A revised damage assessment index D, has been proposed to assess of damage degree. Moreover, finite-element analysis for the shear wall before and after retrofit retrofitting was established in OpenSees and verified with experimental results. The finite element results and test results were in good agreement. Finally, parametric analysis was performed.

• Steel and Composite Structures
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• v.19 no.5
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• pp.1055-1075
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• 2015

In order to investigate the accuracy and applicability of steel equivalent constitutive model, the calculated results were compared with typical tests of steel frames under static and dynamic loading patterns firstly. Secondly, four widely used models for time history analysis of steel frames were compared to discuss the applicability and efficiency of different methods, including shell element model, multi-scale model, equivalent constitutive model (ECM) and traditional beam element model (especially bilinear model). Four-story steel frame models of above-mentioned finite element methods were established. The structural deformation, failure modes and the computational efficiency of different models were compared. Finally, the equivalent constitutive model was applied in seismic incremental dynamic analysis of a ten-floor steel frame and compared with the cyclic hardening model without considering damage and degradation. Meanwhile, the effects of damage and degradation on the seismic performance of steel frame were discussed in depth. The analysis results showed that: damages would lead to larger deformations. Therefore, when the calculated results of steel structures subjected to rare earthquake without considering damage were close to the collapse limit, the actual story drift of structure might already exceed the limit, leading to a certain security risk. ECM could simulate the damage and degradation behaviors of steel structures more accurately, and improve the calculation accuracy of traditional beam element model with acceptable computational efficiency.