• Smart Structures and Systems
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• 제32권1호
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• pp.49-59
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• 2023

A bridge transportation network supplies products from various source nodes to destination nodes through bridge structures in a target region. However, recent frequent earthquakes have caused damage to bridge structures, resulting in extreme direct damage to the target area as well as indirect damage to other lifeline structures. Therefore, in this study, a surrogate model-based comprehensive framework to estimate the seismic resilience of bridge transportation networks is proposed. For this purpose, total system travel time (TSTT) is introduced for accurate performance indicator of the bridge transportation network, and an artificial neural network (ANN)-based surrogate model is constructed to reduce traffic analysis time for high-dimensional TSTT computation. The proposed framework includes procedures for constructing an ANN-based surrogate model to accelerate network performance computation, as well as conventional procedures such as direct Monte Carlo simulation (MCS) calculation and bridge restoration calculation. To demonstrate the proposed framework, Pohang bridge transportation network is reconstructed based on geographic information system (GIS) data, and an ANN model is constructed with the damage states of the transportation network and TSTT using the representative earthquake epicenter in the target area. For obtaining the seismic resilience curve of the Pohang region, five epicenters are considered, with earthquake magnitudes 6.0 to 8.0, and the direct and indirect damages of the bridge transportation network are evaluated. Thus, it is concluded that the proposed surrogate model-based framework can efficiently evaluate the seismic resilience of a high-dimensional bridge transportation network, and also it can be used for decision-making to minimize damage.

• Structural Engineering and Mechanics
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• 제32권2호
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• pp.193-212
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• 2009

The resilience of a city confronted with a terrorist bomb attack is the background of the paper. The resilience strongly depends on vital infrastructure and the physical protection of people. The protection buildings provide in case of an external explosion is one of the important elements in safety assessment. Besides the aspect of protection, buildings facilitate and enable many functions, e.g., offices, data storage, -handling and -transfer, energy supply, banks, shopping malls etc. When a building is damaged, the loss of functions is directly related to the location, amount of damage and the damage level. At TNO Defence, Security and Safety methods are developed to quantify the resilience of city infrastructure systems (Weerheijm et al. 2007b). In this framework, the dynamic response, damage levels and residual bearing capacity of multi-storey RC buildings is studied. The current paper addresses the aspects of dynamic response and progressive collapse, as well as the proposed method to relate the structural damage to a volume-damage parameter, which can be linked to the loss of functionality. After a general introduction to the research programme and progressive collapse, the study of the dynamic response and damage due to blast loading for a single RC element is described. Shock tube experiments on plates are used as a reference to study the possibilities of engineering methods and an explicit finite element code to quantify the response and residual bearing capacity. Next the dynamic response and progressive collapse of a multi storey RC building is studied numerically, using a number of models. Conclusions are drawn on the ability to predict initial blast damage and progressive collapse. Finally the link between the structural damage of a building and its loss of functionality is described, which is essential input for the envisaged method to quantify the resilience of city infrastructure.

• 한국안전학회지
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• 제38권1호
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• pp.18-24
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• 2023

Severe natural disasters and man-made attacks such as terrorism are causing unprecedented disruptions in power systems. Due to rapid climate change and the aging of energy infrastructure, both the frequency of failure and the level of damage are expected to increase. Resilience is a concept proposed to respond to extreme disaster events that have a low probability of occurrence but cause enormous damage and is defined as the ability of a system to recover to its original function after a disaster. Resilience is a comprehensive indicator that can include system performance before and after a disaster and focuses on preparing for all possible disaster scenarios and having quick and efficient recovery actions after an incident. Various studies have been conducted to evaluate resilience, but studies on economic damage considering the duration of a power outage are scarce. In this study, we propose an optimal algorithm that can identify failures after an extreme disaster and restore the load on the distribution system through emergency distributed power generation input and system reconfiguration. After that, the cost of power outage damage is analyzed by applying VoLL and CDF according to each restoration strategy.

• 한국융합학회논문지
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• 제9권2호
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• pp.331-340
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• 2018

본 연구의 목적은 청소년의 학대피해경험이 공격성에 미치는 영향에서 자아탄력성 매개효과를 검증하는 것이며, 이를 위해 한국아동 청소년패널조사 초4 패널 중에서 7차년도(2016년) 데이터를 사용하였다. 분석방법은 SPSS WIN 21.0을 사용하여 대상의 일반적특성을 파악하기 위해 빈도분석, 기술통계를 실시하였으며, 다중공선성을 확인 한 후 매개변인 효과를 하였다. 그리고 매개효과 경로분석을 위해 Sobel Test를 실시하였다. 연구결과는 다음과 같다. 첫째, 청소년의 학대피해경험이 공격성에 유의하게 영향을 미치는 것으로 나타났다. 둘째, 청소년의 학대피해경험이 공격성에 미치는 영향에서 자아탄력성이 부분매개효과가 있은 것으로 나타났다. 본 연구의 결과는 피학대청소년을 대상으로 자아탄력성 강화의 중요성과 모든 청소년들의 성공적인 성인기를 맞이할 수 있도록 예방적 차원에서 자아탄력성 강화가 필요함에 대한 실증적 자료를 제공함으로써 의미를 가지며, 이를 토대로 청소년을 대상으로는 자아탄력성 강화 프로그램이 제공이 사회복지실천에서 필요성을 제언하였다.

• 한국도로학회논문집
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• 제20권1호
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• pp.35-45
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• 2018

PURPOSES : This study examines the performance changes of road networks according to the strength of a disaster, and proposes a method for estimating the quantitative resilience according to the road-network performance changes and damage scale. This study also selected high-influence road sections, according to disasters targeting the road network, and aimed to analyze their hazard resilience from the network aspect through a scenario analysis of the damage recovery after a disaster occurred. METHODS : The analysis was conducted targeting Sejong City in South Korea. The disaster situation was set up using the TransCAD and VISSIM traffic-simulation software. First, the study analyzed how road-network damage changed the user's travel pattern and travel time, and how it affected the complete network. Secondly, the functional aspects of the road networks were analyzed using quantitative resilience. Finally, based on the road-network performance change and resilience, priority-management road sections were selected. RESULTS : According to the analysis results, when a road section has relatively low connectivity and low traffic, its effect on the complete network is insignificant. Moreover, certain road sections with relatively high importance can suffer a performance loss from major damage, for e.g., sections where bridges, tunnels, or underground roads are located, roads where no bypasses exist or they exist far from the concerned road, including entrances and exits to suburban areas. Relatively important roads have the potential to significantly degrade the network performance when a disaster occurs. Because of the high risk of delays or isolation, they may lead to secondary damage. Thus, it is necessary to manage the roads to maintain their performance. CONCLUSIONS : As a baseline study to establish measures for traffic prevention, this study considered the performance of a road network, selected high-influence road sections within the road network, and analyzed the quantitative resilience of the road network according to scenarios. The road users' passage-pattern changes were analyzed through simulation analysis using the User Equilibrium model. Based on the analysis results, the resilience in each scenario was examined and compared. Sections where a road's performance loss had a significant influence on the network were targeted. The study results were judged to become basic research data for establishing response plans to restore the original functions and performance of the destroyed and damage road networks, and for selecting maintenance priorities.

• 환경영향평가
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• 제32권6호
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• pp.463-472
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• 2023

산불에 대한 피해액과 피해 면적은 전 세계적으로 커지고 있지만 피해 후 복원 방법에 따른 효과연구는 부족한 현실이다. 본 연구는 Sentinel-2B 위성 영상과 임상도를 활용하여 산불 피해 면적을 산출하고, 임상에 따른 산불 피해 강도를 분석하였다. 또한, 다양한 파장대를 활용하여 식생지수를 계산하고, 이를 토대로 복원 방법에 따른 식생 회복력을 -1.0에서 1.0 범위 내에서 정량적으로 분석하였다. 그 결과 침엽수림 비율이 높은 지역에서 높은 강도의 산불 피해가 발생하였고, 상대적으로 혼효림과 활엽수림의 비율이 높은 지역에서 낮은 강도의 산불 피해 경향을 보였다. 산불 발생 이후 인공림과 천연림에서의 식생 회복률을 분석한 결과, 인공림은 산불 발생 이전 대비 약 92%, 천연림은 약 101% 식생을 회복하였으며 인공림보다 천연림에서 식생 회복력이 우수한 것을 확인할 수 있었다. 본 연구는 임상에 따른 산불 피해 강도를 분석하고 복원 방법에 따른 식생 회복력을 평가함으로써 산불 피해를 줄이기 위한 수목 선정에 기초자료를 제공하고 복원방법에 따른 식생회복력을 비교하는데 의의가 있다.

• 한국콘텐츠학회논문지
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• 제16권3호
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• pp.102-115
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• 2016

본 연구는 중학생 청소년의 학대피해경험이 자아탄력성에 미치는 영향과 사회적 지지의 조절효과를 살펴보았다. 이를 위하여 부산시내 중학생 1, 2, 3학년 568명을 대상으로 조사하여 분석하였다. 먼저 청소년의 피학대경험은 자아탄력성에 영향을 미치는 것으로 나타났다. 구체적으로 학년이 낮을수록 그리고 학대피해 경험이 없을수록 자아탄력성은 증가하였다. 두 번째, 청소년의 피학대경험이 자아탄력성에 미치는 영향에서 사회적 지지는 조절효과를 가는 것으로 나타났다. 이상의 결과를 중심으로 학대피해 청소년의 부정적 경험에도 불구하고 자신의 환경과 상황을 이겨낼 수 있는 힘이라고 할 수 있는 자아탄력성을 높이기 위하여 가정, 학교, 지역사회와 국가의 사회적 지지 방안을 제언하였다.

• Structural Engineering and Mechanics
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• 제52권6호
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• pp.1157-1176
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• 2014

The objective of this research is to develop a practical design and assessment approach of steel frames with steel slit walls (SSWs) that focuses on the damage-control behavior to enhance the structural resilience. The yielding sequence of SSWs and frame components is found to be a critical issue for the damage-control behavior and the design of systems. The design concept is validated by the full-scale experiments presented in this paper. Based on a modified energy-balance model, a procedure for designing and assessing the system motivated by the framework regarding the equilibrium of the energy demand and the energy capacity is proposed. The damage-control spectra constructed by strength reduction factors calculated from single-degree-of-freedom systems considering the post stiffness are addressed. A quantitative damage-control index to evaluate the system is also derived. The applicability of the proposed approach is validated by the evaluation of example structures with nonlinear dynamic analyses. The observations regarding the structural response and the prediction during selected ground motions demonstrate that the proposed approach can be applied to damage-control design and assessment of systems with satisfactory accuracy.

• Coupled systems mechanics
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• 제9권2호
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• pp.91-110
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• 2020

The reliability of structures is affected by various impacts that generally have a negative effect, from extreme weather conditions, due to climate change to natural or man-made hazards. In recent years, extreme loading has had an enormous impact on the resilience of structures as one of the most important characteristics of the sound design of structures, besides the structural integrity and robustness. Resilience can be defined as the ability of the structure to absorb or avoid damage without suffering complete failure, and it can be chosen as the main objective of design, maintenance and restoration for structures and infrastructure. The latter needs further clarification (which is done in this paper), to achieve the clarity of goals compared to robustness which is defined in Eurocode EN 1991-1-7 as: "the ability of a structure to withstand events like fire, explosions, impact or the consequences of human error, without being damaged to an extent disproportionate to the original cause". Many existing structures are more vulnerable to the natural or man-made hazards due to their material deterioration, and a further decrease of its loadbearing capacity, modifying the structural performance and functionality and, subsequently, the system resilience. Due to currently frequent extreme events, the design philosophy is shifting from Performance-Based Design to Resilience-Based Design and from unit to system (community) resilience. The paper provides an overview of such design evolution with indicative needs for Resilience-Based Design giving few conducted examples.

• 문화기술의 융합
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• 제5권4호
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• pp.387-394
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• 2019

본 연구에서는 도시철도 침목플로팅궤도(STEDEF) 궤도구성품의 손상영향을 분석하기 위하여 20년 이상 공용중인 현장에서 시료를 채취하여 궤도재료에 대한 육안검사와 실내시험 및 유한요소해석을 통해 궤도구성품의 손상취약부를 분석하였다. 육안검사결과 레일패드와 체결구는 특이사항이 없었으나 침목방진상자는 모서리부분의 마모 및 찢어지는 현상이 발생하였다. 침목방진패드는 두께감소 및 피로경화층이 뚜렷하게 조사되었다. 레일패드와 침목방진패드에 대한 스프링강성 시험결과, 레일패드의 노후는 뚜렷하지 않았으나 침목방진패드는 설계기준치를 크게 상회하는 것으로 나타나 침목방진패드는 통과톤수에 직접적인 영향을 받는 것으로 분석되었다. 현장시료의 열화상태와 수치해석 결과와의 비교결과, 수치해석모델의 응력 및 변위 집중위치와 현장시료의 손상위치가 일치하는 것으로 나타나 공용중인 침목플로팅궤도 궤도구성품의 손상취약부를 실험 및 해석적으로 입증하였다.