• 한국기계가공학회지
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• 제20권9호
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• pp.42-47
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• 2021

A one-touch descending lifeline that can easily be installed and rapidly evacuated in the event of a fire accident in high-rise buildings was proposed to overcome difficulties of conventional descending lifeline such as complex installation methods and procedures. However, this lifeline exhibits limitations such as restrictions in installation location and large apparatus size. Therefore, this paper proposes a sliding-type descending lifeline, which has a similar operation to that of current one-touch descending lifeline and solves the aforementioned limitations. A double square link mechanism including a sliding four-bar linkage is proposed and the descending lifeline support is redesigned to unfold in two different planes, allowing 3D movement. Additionally, the shape of the support frame is designed to obtain two attachment surfaces that can be attached to a wall, irrespective of the angle between the window and the inner wall. FEA analysis using ABAQUS is performed to ensure that the robustness of the presented support complies with the Fire Control Act Enforcement Decree. Finally, the feasibility of the proposed sliding one-touch descending lifeline is verified through fabrication.

• Smart Structures and Systems
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• 제16권5호
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• pp.873-889
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• 2015

In civil engineering, probabilistic seismic risk assessment is used to predict the economic damage to a lifeline system of possible future earthquakes. The results are used to plan mitigation measures and to strengthen the structures where necessary. Instead, after an earthquake public authorities need mathematical models that compute: the damage caused by the earthquake to the individual vulnerable components and links, and the global behavior of the lifeline system. In this study, a framework that was developed and used for prediction purpose is modified to assess the consequences of an earthquake in quasi real-time after such earthquake happened. This is possible because nowadays entire seismic regions are instrumented with tight networks of strong motion stations, which provide and broadcast accurate intensity measure maps of the event to the public within minutes. The framework uses the broadcasted map and calculates the damage to the lifeline system and its component in quasi real-time. The results give the authorities the most likely status of the system. This helps emergency personnel to deal with the damage and to prioritize visual inspections and repairs. A highway transportation network is used as a test bed but any lifeline system can be analyzed.

• 한국건설관리학회논문집
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• 제15권4호
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• pp.139-149
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• 2014

재난 이후 라이프라인의 손상은 지역사회 내 공공서비스의 제공을 지연시켜 서비스를 필요로 하는 시설물로 피해를 확산시킬 수 있다. 이에 라이프라인의 정확한 피해 평가를 기반으로 한 신속한 라이프라인의 복구가 요구되고 있으나, 라이프라인 구성요소간의 복잡한 의존관계와 네트워크적 성격으로 인해 복구계획을 수립하는데 어려움이 따른다. 또한 라이프라인의 위험도 평가 및 영향력 분석과 같은 기존의 연구들 역시 라이프라인 구성요소 간의 상호작용을 확인하기에는 한계가 있다. 따라서 본 연구에서는 에이전트 기반 모델을 활용하여 라이프라인 구성요소가 전체 네트워크시스템에 발현하는 연쇄피해효과를 확인하고, 라이프라인 간 상호의존성을 고려한 라이프라인 기능회복 모델을 제시하고자 한다. 이를 통해 전체 네트워크에 파급효과가 큰 라이프라인 구성요소에 우선적으로 복구 자원을 할당할 수 있도록 지원하여, 라이프라인 서비스 공급 중단으로 인한 지역사회의 피해확산을 경감시킬 수 있을 것이라 기대된다.

• 한국기계가공학회지
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• 제20권6호
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• pp.108-113
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• 2021

Recently, a new concept of a one-touch descending lifeline has been proposed to address the drawbacks of the conventional descending lifeline, which can be easily installed and quickly evacuated in the case of a fire emergency. All separate parts for escape are initially mounted in a box, and the link-type support is spread out of the window by pushing the handle attached to the box. In this study, the proposed double square linkage mechanism was redesigned, and its safety is verified by determining an appropriate moment of inertia of the link through finite element analysis using Abaqus. The shape and assembling method of the reel and speed controller were also modified such that the safety belt was simultaneously unfolded with link-type support. Finally, the feasibility of the proposed one-touch all-in-one descending lifeline was confirmed through fabrication.

• 전자통신동향분석
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• 제37권4호
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• pp.19-27
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• 2022

The coronavirus disease 2019 (COVID-19) pandemic has significantly changed the Lifeline Program, a telecommunications rate discount program for low-income Americans. As the reliance on online activities such as remote work, distance education, and online shopping grows because of the spread of COVID-19, there is a concern that the digital divide will widen among low-income households that struggle to access internet infrastructure due to the burden of access rates. Accordingly, the US Congress passed a bill to help lower the internet bill for low-income households using the government budget to close the digital divide. The Lifeline Program, which is a part of the universal service obligation, has been in charge of the telecommunications rate discount for low-income households. However, according to the new law, the internet rate discount program based on the government budget was implemented beginning in 2021. As the internet rate discount based on the government budget begins, the US telecommunication rate discount system is transitioning from a system in which telecommunication industry support was borne by operators to one in which public support from the government budget will play a significant role. In this paper, we will look at recent changes in the US telecommunications rate discount program and their implications.

• Earthquakes and Structures
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• 제26권2호
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• pp.87-96
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• 2024

This paper proposes a logistic multinomial regression approach to model the spatial cross-correlation of damage probabilities among different damage states in an expanded transportation network. Utilizing Bayesian theory and the multinomial logistic model, we analyze the damage states and probabilities of bridges while incorporating damage correlation. This correlation is considered both between bridges in a network and within each bridge's damage states. The correlation model of damage probabilities is applied to the seismic assessment of a portion of Tehran's transportation network, encompassing 26 bridges. Additionally, we introduce extra daily traffic time (EDTT) as an operational parameter of the transportation network and employ the shortest path algorithm to determine the path between two nodes. Our results demonstrate that incorporating the correlation of damage probabilities reduces the travel time of the selected network. The average decrease in travel time for the correlated case compared to the uncorrelated case, using two selected EDTT models, is 53% and 71%, respectively.

• 한국기계가공학회지
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• 제19권5호
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• pp.21-26
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• 2020

A descending lifeline is the only self-escape fire apparatus for fire in high-rise buildings and is installed in most buildings according to fire-fighting law. However, it is difficult to properly use and quickly evacuate during an emergency due to its complex installation methods and procedures, even if users are pre-educated. In this paper, a new one-touch descending lifeline, which simplifies usage procedures and can be used regardless of whether users are educated, is proposed to solve the drawbacks of the conventional descending lifeline. All separate parts that require additional installation are initially assembled in a box, and the concept of a double square linkage is proposed to enable escape in a single motion of pushing the handle attached to the box. Three steps of kinematic design are explored to determine an appropriate configuration of double square linkage, and its dimensions are determined using Matlab and NX CAD software. The proposed all-in-one descending lifeline also follows the enforcement decree of the Fire Control Act, and its feasibility is verified through fabrication.

• Structural Engineering and Mechanics
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• 제32권1호
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• pp.147-165
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• 2009

This study proposes a certain measure or investment strategy for decision making associated with seismic retrofitting. This strategy reduces the risk of a large-scale malfunction such as water supply loss under seismic risks. The authors developed a stochastic value index that will be used in the overall evaluation of social benefit, income gain, life cycle costs and failure compensation associated with existing lifeline systems damaged by an earthquake during the remaining service period. Optimal seismic disaster prevention investment of deteriorated lifeline systems is discussed. Finally, the present study provides a performance-based design method for seismic retrofitting strategies of existing lifelines which are carried out using the target probabilities of value loss and structural failure.

• 한국건설관리학회논문집
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• 제19권3호
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• pp.33-42
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• 2018

손상된 라이프라인 시스템의 공공서비스 제공 지연 예측은 지진 대응 체계 마련의 첫 단계이다. 그러나 라이프라인 시스템의 서비스제공가능도는 개별 구조물의 물리적 손상뿐만 아니라 인접한 구조물들로부터의 피해파급에 의해 변동될 수 있다. 이에 본 연구는 라이프라인 시스템의 기능 저하를 유발하는 공통원인피해와 연쇄피해의 발생 확률을 추론하기 위해 베이지안 모형을 작성하고 피해의 인과관계를 고려하여 최종 수요자 중심의 네트워크 강건성을 평가하는 방안을 제시하였다. 또한 완화대책에 따른 네트워크 강건성을 분석하기 위해 국내 대구경북지역의 전력 및 상수도 시스템을 대상으로 지진 규모에 따른 공공서비스의 공급 지연 확률을 예측하였다. 그 결과 사례 지역의 경우 안정적인 전력과 상수 수급을 위해 라이프라인 네트워크를 구성하는 노드들 간 피해파급을 저감하는 것이 효과적임을 확인하였다. 본 연구는 지진 피해 진단의 다양한 불확실성 간 인과관계를 도식화하였다는 데에 의의가 있으며, 지속 가능한 공공서비스 확보를 위한 지역단위 대책 수립을 지원할 수 있을 것으로 기대된다.

• 한국안전학회지
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• 제37권3호
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• pp.1-8
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• 2022

Workplace accidents are common while working at elevations. Thus, various safety measures such as safety handrails and horizontal safety nets are implemented to prevent falls. The minimum safety measure is the lifeline installation. However, because its standards have not been clearly established, it is often misused, resulting in inappropriate knot methods that increase the chance of accidents while working at elevations. Therefore, clarifying the appropriate usage methods or criteria for the various lifelines is required in the field. This study proposed an appropriate installation method by experimentally and numerically evaluating the change in strength according to the fixed knot lifeline method. In addition, three knot methods were specified for each material. The results obtained are expected to contribute to lessening falls through the establishment of lifeline installation standards and the development of appropriate parts.