• Steel and Composite Structures
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• v.20 no.5
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• pp.999-1022
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• 2016

The use of Carbon Fiber Reinforced Polymer (CFRP) to strengthen steel structures has attracted the attention of researchers greatly. Previous studies demonstrated bonding of CFRP plates to the steel sections has been a successful method to increase the mechanical properties. However, the main limitation to popular use of steel/CFRP strengthening system is the concern on durability of bonding between steel and CFRP in various environmental conditions. The paper evaluates the performance of I-section steel beams strengthened with pultruded CFRP plate on the bottom flange after exposure to diverse conditions including natural tropical climate, wet/dry cycles, plain water, salt water and acidic solution. Four-point bending tests were performed at specific intervals and the mechanical properties were compared to the control beam. Besides, the ductility of the strengthened beams and distribution of shear stress in adhesive layer were investigated thoroughly. The study found the adhesive layer was the critical part and the performance of the system related directly to its behavior. The highest strength degradation was observed for the beams immersed in salt water around 18% after 8 months exposure. Besides, the ductility of all strengthened beams increased after exposure. A theoretical procedure was employed to model the degradation of epoxy adhesive.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.5
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• pp.1027-1037
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• 2012

With response to the critical issue of global warming, Smart Grid system has been extensively investigated as next efficient power grid system. Domestically, Korean is trying to expand the usage of Electric Vehicles (EVs) and the charging infrastructure in order to replace the current transportation using fossil fuels holding 20% of overall CO2 emission. The EVs charging infrastructures are combined with IT technologies to build intelligent environments but have considerable number of cyber security issues because of its inherent nature of the technologies. This work not only provides logical architecture of EV charging infrastructures with security threats based on them but also analyses security requirements against security threats in order to overcome the adversarial activities to Smart Grid.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.907-918
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• 2019

The purpose of this study is to understand the cybersecurity policies and critical infrastructure protection of the United States through analyzing Donald Trump's administration executive orders, the national cyber strategy, and the legislation. The analysis has three findings. First, the Department of Homeland Security (DHS) became a main agent in the cybersecurity while the role of the White House was reduced. Second, Trump's administration expanded its role and mission in the policy area by extending the meaning of critical infrastructure. Third, in the case of cyber threats, the government can be involved in the operation of critical infrastructures in the private sector. The opinions of the professional bureaucrats and DHS were more reflected in the direction of the cybersecurity policy than those of the White House. In contrast to Barack Obama's administration, the Trump administration's cybersecurity strategies were not much studied. This study provides insights for improving cybersecurity policies and critical infrastructure protection.

• Structural Engineering and Mechanics
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• v.76 no.2
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• pp.251-267
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• 2020

Transmission tower-line systems have come to represent one of the most important infrastructures in today's society. Recent strong earthquakes revealed that transmission tower-line systems are vulnerable to earthquake excitations, and that ground motions may arrive at such structures from any direction during an earthquake event. Considering these premises, this paper presents experimental and numerical studies on the dynamic responses of a 1000 kV ultrahigh-voltage (UHV) transmission tower-line system under different seismic incidence angles. Specifically, a 1:25 reduced-scale experimental prototype model is designed and manufactured, and a series of shaking table tests are carried out. The influence of the seismic incidence angle on the dynamic structural response is discussed based on the experimental data. Additionally, the incidence angles corresponding to the maximum peak displacement of the top of the tower relative to the ground (referred to herein as the critical seismic incidence angles) are summarized. The experimental results demonstrate that seismic incidence angle has a significant influence on the dynamic responses of transmission tower-line systems. Subsequently, an approximation method is employed to orient the critical seismic incidence angle, and a corresponding finite element (FE) analysis is carried out. The angles obtained from the approximation method are compared with those acquired from the numerical simulation and shaking table tests, and good agreement is observed. The results demonstrate that the approximation method can properly predict the critical seismic incidence angles of transmission tower-line systems. This research enriches the available experimental data and provides a simple and convenient method to assess the seismic performance of UHV transmission systems.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1735-1741
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• 2011

The safety of station structures among railway infrastructures should be considered as a top priority because hundreds of thousands passengers a day take a subway. The station structures, which have been being operated since the 1970s, are especially vulnerable to the earthquake and long-term vibrations such as ambient train vibrations as well. This is why the structural-health monitoring system of station structures should be required. For these reason, Korean government has made an effort to develop the structural health-monitoring system of them, which can evaluate the health-state of station structures as well as can monitor the vulnerable structural members in real-time. Then, through the monitoring system, the vulnerable structural members could be retrofitted. For the development of health-state evaluation method for station structures with the real-time sensing data measured in the fields, authors carried out the numerical simulations to develop evaluation algorithms based on statistical pattern recognition techniques. In this study, the dynamic behavior of Chungmuro station in Seoul was numerically analyzed and then critical members were chosen. Damages were artificially simulated at the selected critical members of the numerical model. And, the supervised and unsupervised learning based pattern recognition algorithms were applied to quantify and localize the structural defects.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.8
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• pp.781-790
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• 2013

Nowadays, national critical infrastructures have been known to be highly vulnerable to the EMP threats which are internationally growing. But their realistic solutions have been not made by the lack of detailed rules and regulations in current laws, however, which cover most of cyber threats. This paper takes a look at the domestic and overseas trends on the EMP protections, and proposes the revision directives of relevant laws and the contents included into the proposed legislation. Among them, the amendment of the current "Information Infrastructure Protection Act" is considered to be the most effective, including provisions on protected informations, industrial promotions, R&D supports, education, etc. Anyway, this paper is expected to be helpful for introducing an effective legal scheme on the CIP against EMP threats. domestic rule.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.25 no.6
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• pp.65-75
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• 2022

Urban flood management(UFM) strategy ought to consider the connections and interactions between existing and new infrastructures to manage stormwater and improve the capacity to treat water. It is also important to demonstrate strategies that can be implemented to reduce the flow at flooding sources and minimize flood risk at critical locations. Although the general theory of spatial impact is popular, modeling guidelines that can provide information for implementation in real-world plans are still lacking. Under such background, this study conducted a modeling research based on an actual target site to confirm the hypothesis that it is appropriate to install green infrastructure(GI) in the source area and to take structural protection measures in the impact area, as summarized in previous studies. The results of the study proved the hypothesis, but the results were different from the hypothesis depending on which hydrological performance indicators were targeted. This study will contribute to demonstrating the effectiveness of strategies that can be implemented to reduce the flow at flooding sources and minimize the risk of flooding in critical locations in terms of spatial planning and regeneration.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.674-681
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• 2021

Cyber attacks targeting critical infrastructure are on the rise. Critical infrastructure is defined as core infrastructures within a country with a high degree of interdependence between the different structures; therefore, it is difficult to sufficiently protect it using outdated cybersecurity techniques. In particular, the distinction between the physical and logical risks of critical infrastructure is becoming ambiguous; therefore, risk management from a comprehensive perspective must be implemented. Accordingly, as a means of further actively protecting critical infrastructure, major countries have begun to apply their security and cybersecurity systems by design, as a more expanded concept is now being considered. This proactive security approach (CSbD, Cybersecurity by Design) includes not only securing the stability of software (SW) safety design and management, but also physical politics and device (HW) safety, precautionary and blocking measures, and overall resilience. It involves a comprehensive security system. Therefore, this study compares and analyzes security by design measures towards critical infrastructure that are leading the way in the US, Europe, and Singapore. It reflects the results of an analysis of optimal cybersecurity solutions for critical infrastructure. I would like to present a plan for applying by Design.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.32-38
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• 2020

The deployment of geographically distributed wireless sensors has greatly elevated the capability of monitoring structural health in social-overhead capital (SOC) public infrastructures. This paper deals with the utilization of a distributed mobility management (DMM) approach for the deployment of wireless sensing devices in a structural health monitoring system (SHM). Then, a wireless sensing mechanism utilizing low-energy adaptive clustering hierarchy (LEACH)-based clustering algorithm for smart sensors has been analyzed to support the seamless data transmission of structural health information which is essentially important to guarantee public safety. The clustering of smart sensors will be able to provide real-time monitoring of structural health and a filtering algorithm to boost the transmission of critical information over heterogeneous wireless and mobile networks.

• Review of KIISC
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• v.24 no.5
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• pp.39-45
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• 2014

최근, 에너지, 정보통신, 방위산업, 정부, 금융 등 국가기반시설(national critical infrastructures)들에 대한 사이버 보안 위협이 급격히 증가하고 있으며 이에 대응하기 위해 미국을 비롯한 주요 국가에서는 감시제어 및 데이터 취득 시스템(SCADA: Supervisory Control and Data Acquisition)에 대한 사이버 보안에 많은 노력을 기울이고 있다. 특히, 주요 국가 기반시설은 다양한 실시간 분산 제어시스템 및 네트워크를 통해 사이버 세계(cyber world)와 물리적 세계(physical world)를 연계한다. 하지만 이 같은 역동성(dynamic), 확장성(scalability), 다양성(diversity)으로 특징지어질수 있는 실시간 분산 제어시스템간의 상호연결과 연동을 통해 구성되는 해당시설은 기존의 보안기술 적용을 통해 보안성향상을 기대할 수 없다. 따라서 본고에서는 실시간 분산 제어시스템과 다양한 네트워크로 구성되는 기반시설들을 대상으로 하는 여러 가지 보안 위협 및 특징을 소개하고 이에 대응하기 위한 전략 및 연구기술 동향을 간략히 서술한다.