• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.5 no.2
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• pp.20-26
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• 2009

The dominant incidents category for onshore and offshore natural gas transmission pipelines in the world is associated with outside forces. Incidents in the outside forces category embrace acts of nature, which typically cause widespread structural damage, as well as act of man, whose effects tend to cause dents and/or gouges localized at point of contact that are referred to as mechanical damage. Therefore, these damage types must be better addressed to avoid unnecessary and costly repairs and the possibility of catastrophic events. First of all, the characterizing features of mechanical damage in gas pipelines were evaluated by using of excavator or boring machine. There is no reliable method for evaluating the safe operating pressure of pipeline affected by mechanical damage. It is especially important to evaluate the remaining strength of damaged pipelines due to outside force. Therefore, the full scale burst tests were conducted to evaluate the remaining strength of pipe with mechanical damage that combines a dent and a gouge. This paper is supposed to provide information that will assist in developing a criterion to assess serviceability in pipelines with mechanical damage.

• Earthquakes and Structures
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• v.6 no.6
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• pp.581-609
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• 2014

Reinforced concrete (RC) structures are likely to experience damage when subjected to earthquakes. Damage index (DI) has been recognised as an advanced tool of quantitatively expressing the extent of damage in such structures. Last 30 years have seen many concepts for DI proposed in order to calibrate the observed levels of damage. The current research briefly reviews all available concepts and investigates their relative merits and limitations with a view to proposing a new concept based on residual deformation. Currently available DIs are classified into two broad categories - non-cumulative DI and cumulative DI. Non-cumulative DIs do not include the effects of cyclic loading, whilst the cumulative concepts produce more rational indication of the level of damage in case of earthquake excitations. Ideally, a DI should vary within a scale of 0 to 1 with 0 representing the state of elastic response, and 1 referring to the state of total collapse. Some of the available DIs do not satisfy these criteria. A new DI based on energy is proposed herein and its performances, both for static and for cyclic loadings, are compared with those obtained using the most widely accepted DI in literature. The proposed DI demonstrates a rational way to predict the extent of damage for a number of case studies. More research is encouraged to address some identified issues.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.427-440
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• 2013

A growing need has developed in the United States to obtain more specific knowledge on the structural integrity of infrastructure due to aging service lives, heavier and more frequent loading conditions, and durability issues. This need has spurred extensive research in the area of structural health monitoring over the past few decades. Several structural health monitoring techniques have been developed that are capable of locating damage in structures using modal strain energy of mode shapes. Typically in the past, bending strain energy has been used in these methods since it is a dominant vibrational mode in many structures and is easily measured. Additionally, there may be cases, such as pipes, shafts, or certain bridges, where structures exhibit significant torsional behavior as well. In this research, torsional strain energy is used to locate damage. The damage index method is used on two numerical models; a cantilevered steel pipe and a simply-supported steel plate girder bridge. Torsion damage indices are compared to bending damage indices to assess their effectiveness at locating damage. The torsion strain energy method is capable of accurately locating damage and providing additional valuable information to both of the structures' behaviors.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.291-308
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• 2013

A novel concept of transmissibility based on a wavelet transform for structural damage detection is presented in this paper. The main objective of the research was the development of a method for detecting slight damage at the incipient stage. As a vibration-based approach, the concept of transmissibility has attracted considerable interest because of its advantages and effectiveness in damage detection. However, like other vibration-based methods, transmissibility-based approaches suffer from insensitivity to slight local damage because of the regularity of the traditional Fourier transform. Therefore, the powerful signal processing techniques must be found to solve this problem. Wavelet transform that is able to capture subtle information in measured signals has received extensive attention in the field of damage detection in recent decades. In this paper, we first propose a novel transmissibility concept based on the wavelet transform. Outlier analysis was adopted to construct a damage detection algorithm with wavelet-based transmissibility. The feasibility of the proposed method was numerically investigated with a typical six-degrees-of-freedom spring-mass system, and comparative investigations were performed with a conventional transmissibility approach. The results demonstrate that the proposed transmissibility is more sensitive than conventional transmissibility, and the former is a promising tool for structural damage detection at the incipient stage.

• Structural Monitoring and Maintenance
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• v.9 no.2
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• pp.179-200
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• 2022

This paper proposes a data-driven methodology for online early damage identification under changing environmental conditions. The proposed method relies on two data analysis methods: feature-based method and hybrid principal component analysis (PCA) and kernel PCA to separate damage from environmental influences. First, spectral sub-band features, namely, spectral sub-band centroids (SSCs) and log spectral sub-band energies (LSSEs), are proposed as damage-sensitive features to extract damage information from measured structural responses. Second, hybrid modeling by integrating PCA and kernel PCA is performed on the spectral sub-band feature matrix for data normalization to extract both linear and nonlinear features for nonlinear procedure monitoring. After feature normalization, suppressing environmental effects, the control charts (Hotelling T² and SPE statistics) is implemented to novelty detection and distinguish damage in structures. The hybrid PCA-KPCA technique is compared to KPCA by applying support vector machine (SVM) to evaluate the effectiveness of its performance in detecting damage. The proposed method is verified through numerical and full-scale studies (a Bridge Health Monitoring (BHM) Benchmark Problem and a cable-stayed bridge in China). The results demonstrate that the proposed method can detect the structural damage accurately and reduce false alarms by suppressing the effects and interference of environmental variations.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.4
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• pp.307-317
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• 2010

The majority of financial and general business organizations have had individual damage from hacking, worms, viruses, cyber attacks, internet fraud, technology and information leaks due to criminal damage. Therefore privacy has become an important issue in the community. This paper examines various elements of the information security management system and discuss about Information Security Management System Models by using the analysis of the financial statue and its level of information security assessment. These analyses were based on the Information Security Management System (ISMS) of Korea Information Security Agency, British's ISO27001, GMITS, ISO/IEC 17799/2005, and COBIT's information security architecture. This model will allow users to manage and secure information safely. Therefore, it is recommended for companies to use the security management plan to improve the companies' financial and information security and to prevent from any risk of exposing the companies' information.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.57-61
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• 2011

Large scale natural disasters such as floods and typhoons due to climate change have recently occurred with severe damage in all over the world. Especially, current disaster investigation in affected area takes too much time because it can be done by handcrafted. Also, it is lack of somewhat accuracy and objectiveness because it is influenced by investigator's judgment. Further, the current disaster investigation is difficult when damage area is very wide or investigator can't reach the affected area. Hence, we developed the integrated damage investigation system using stereo images and information technology for quick, accurate and objective investigation. Also, we applied the system to Bonghwa-gun in Gyeongsangbuk-do in 2008, Jecheon-si in Chungcheongbuk-do in 2009, and Namwon-si in Jeollabuk-do and Hapcheon-gun in Gyeongsangnam-do in 2010. This paper presents advancement and application of integrated damage investigation system using stereo images and information technology considering mobility, stability and user convenience in field.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.1
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• pp.167-179
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• 2016

The safety of SOC facilities is constantly under threat by the globally increasing abnormal climate. Responding to disasters requires prompt decision-making such as suggesting evacuation paths. For doing so, spatio-temporal information with convergence of disaster information and SOC facility information must be utilized. Such information is being collected separately by the government or related organizations, but not collectively. The collective control of the separately collected disaster information and the generation of SOC facility safety and damage information are required for prompt disaster response. Also, as disaster information requires spatio-temporal convergence in its nature, the construction of an inventory that integrates related information and assists disaster response decision-making is required. A plan to construct a facility importance, risk, and damage estimation inventory for assisting prompt disaster response decision-making is suggested in this study. Through this study, the disaster and SOC facility-related data, which are being managed separately, can be collected and standardized. The integrated information required for the estimation of facility importance, risk, and damage can be provided. The suggested system is expected to be used as a decision-making tool for proactive disaster response.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.1
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• pp.215-227
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• 2018

As Korea is rapidly becoming an IT powerhouse in the short term, various side effects such as cyber violence, personal information leakage and cyber terrorism are emerging as new social problems. Especially, the seriousness of leakage of personal information, which is the basis of safe cyber life, has been highlighted all over the world. In this regard, it is necessary to estimate the amount of the damage cost due to the leakage of personal information. In this study, we propose four evaluation methods to calculate the cost of damages due to personal information leakage according to average real transactions value, personally recognized value, compensation amount basis, and comparison to similar countries. We analyzed data from 2007 to 2016 to collect personal information leakage cases for 10 years and estimated the cost of damages. The number of cases used in the estimation is 65, and the total number of personal information leakage is about 430 million. The estimated cost of personal information leakage in 2016 was estimated to be at least KRW 7.4 billion, up to KRW 220 billion, and the 10 year average was estimated at from KRW 10.7 billion to KRW 307 billion per year. Also, we could find out the singularity that the estimated damage due to personal information leakage increases every three years. In the future, this study will be able to provide an index that can measure the damage cost caused by the leakage of personal information more accurately, and it can be used as an index of measures to reduce the damage cost due to personal information leakage.

• Smart Structures and Systems
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• v.11 no.5
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• pp.497-510
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• 2013

Quick, accurate damage monitoring is strongly required for damage assessment in the aftermath of a large natural disaster. Wireless sensor networks are promising technologies to acquire damage information in a citywide area. The wireless sensor networks, however, would be faced with difficulty to collect data in real-time and to expand the scalability of the networks. This paper discusses a scheme of network architecture to cove a whole city in multi-tier heterogeneous networks, which consist of wireless sensor networks, access networks and a backbone network. We first review previous studies for citywide damage monitoring, and then discuss the feature of multi-tier heterogeneous networks to cover a citywide area.