• 대한토목학회논문집
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• 제43권6호
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• pp.831-839
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• 2023

본 연구는 재난현장에서 실시간으로 발생하는 정보들을 신속하게 수집·분석하여 정확한 재난현장상황파악과 의사결정을 지원할 수 있는 현장지원시스템의 통합방안을 제안하고, 프로토타입 시뮬레이션을 통해 현장 적용성을 검토하는 것에 그 목적이 있다. 이를 위해 재난현장에서 활용 할 수 있는 정보수집·공유·융합 기술에 대해 검토하였으며, 재난관리 전단계에 필요한 정보자원과 정보의 효율적인 흐름을 만들어낼 수 있는 스마트 재난현장지원시스템의 통합방안에 대해 제시하였다. 이를 기반으로 제작된 프로토타입으로 시스템 운용 가능성을 검토하기 위해 풍수해 재난 시나리오를 토대로 시뮬레이션을 진행하였으며, 시스템 내의 다양한 기능들이 정상적으로 구현되어 GIS 상황판에 표출되는 것을 확인하였다. 본 연구를 통해 급변하는 재난환경 속에서 효율적이고 능동적인 재난대응이 가능해질 것이라 기대된다.

• Earthquakes and Structures
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• 제18권3호
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• pp.285-296
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• 2020

Dams are important structures for management of water supply for irrigation or drinking, flood control, and electricity generation. In seismic regions, the structural safety of concrete gravity dams is important due to the high potential of life and economic loss if they fail. Therefore, the seismic analysis of existing dams in seismically active regions is crucial for predicting responses of dams to ground motions. In this paper, earthquake response of concrete gravity dams is investigated using the finite element (FE) method. The FE model accounts for dam-water-foundation rock interaction by considering compressible water, flexible foundation effects, and absorptive reservoir bottom materials. Several uncertainties regarding structural attributes of the dam and external actions are considered to obtain the fragility curves of the dam-water-foundation rock system. The structural uncertainties are sampled using the Latin Hypercube Sampling method. The Pine Flat Dam in the Central Valley of Fresno County, California, is selected to demonstrate the methodology for several limit states. The fragility curves for base sliding, and excessive deformation limit states are obtained by performing non-linear time history analyses. Tensile cracking including the complex state of stress that occurs in dams was also considered. Normal, Log-Normal and Weibull distribution types are considered as possible fits for fragility curves. It was found that the effect of the minimum principal stress on tensile strength is insignificant. It is also found that the probability of failure of tensile cracking is higher than that for base sliding of the dam. Furthermore, the loss of reservoir control is unlikely for a moderate earthquake.

• Advances in materials Research
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• 제6권2호
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• pp.155-168
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• 2017

The terrorist attacks and dangers by bomb blast have turned into an emerging issue throughout the world and the protection of the people and structures against terrorist acts depends on the prediction of the response of structures under blast and shock load. In this paper, behavior of aluminum and unidirectionally reinforced E-Glass Epoxy composite plates with and without focal circular holes subjected to shock loading has been identified. For isotropic and orthotropic plates (with and without holes) the classical normal mode approach has been utilized as a part of the processing of theoretical results. To obtain the accurate results, convergence of the results was considered and a number of modes were selected for plate with and without hole individually. Using a shock tube as a loading device, tests have been conducted to composite plates to verify the theoretical results. Moreover, peak dynamic strains, investigated by experiments are also compared with the theoretical values and deviation of the results are discussed accordingly. The strain-time histories are likewise indicated for a specific gauge area for aluminum and composite plates. Comparison of dynamic-amplification factors between the isotropic and the orthotropic plates with and without hole has been discussed.

• Structural Monitoring and Maintenance
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• 제2권2호
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• pp.145-164
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• 2015

Bridge scour is the predominant cause of overwater bridge failures in North America and around the world. Several sensing systems have been developed over the years to detect the extent of scour so that preventative actions can be performed in a timely manner. These sensing systems have drawbacks, such as signal inaccuracy and discontinuity, installation difficulty, and high cost. Therefore, attempts to develop more efficient monitoring schemes continue. In this study, the viability of using optical dissolved oxygen (DO) probes for monitoring scour depths was explored. DO levels are very low in streambed sediments, as compared to the standard level of oxygen in flowing water. Therefore, scour depths can be determined by installing sensors to monitor DO levels at various depths along the buried length of a bridge pier or abutment. The measured DO is negligible when a sensor is buried but would increase significantly once scour occurs and exposes the sensor to flowing water. A set of experiments was conducted in which four dissolved oxygen probes were embedded at different soil depths in the vicinity of a mock bridge pier inside a laboratory flume simulating scour conditions. The results confirmed that DO levels jumped drastically when sensors became exposed during scour hole evolution, thereby providing discrete measurements of the maximum scour depth. Moreover, the DO probes could detect any subsequent refilling of the scour hole through the deposition of sediments. The effect of soil permeability on the sensing response time was also investigated.

• 동아시아경상학회지
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• 제8권4호
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• pp.19-28
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• 2020

Purpose - This study aims to lay the foundation for a desirable direction to solve future environmental problems through framework research on environmental cooperation according to distribution of urbanization between South and North Korea. The article also attempts to explore solution to two Koreas' environmental problems from the cooperative perspective between South and North Korea and draw future policy tasks. Research design, data, and methodology - For methodology, North Korea's legal system to cope with disasters is taken into consideration in terms of literature review. This study also analyzes a series of processes related to North Korea's disaster management through case study, and draws policy measures for North and South Korea's cooperation scope and methods. Result - The results support that North Korea is very vulnerable to environmental disasters due to food shortages, economic sanctions, and enormous natural disaster damages including flood damages occurring each year, because of the lack of disaster prevention infrastructure such as river maintenance. Conclusion - At the current time when North and South Koran exchange and cooperation increase, a disaster management cooperative system is needed for the areas where South and North Korea manage through division. It also suggests that there is a need to establish regulations and procedures for support items in advance for a quick response to disasters in North Korean region.

• 정보보호학회논문지
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• 제21권2호
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• pp.119-129
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• 2011

본 논문은 인터넷 서버의 정상적인 TCP 연결을 방해하는 형태의 DDoS(Distributed Denial of Service) 공격으로부터 서버를 보호하고 원활한 서비스를 제공하기 위한 DDoS 공격 차단 방법에 관한 것이다. 즉, 유효한 TCP 연결만을 전달해주는 기능을 가진 네트워크 인터페이스 카드에서의 고속 TCP 연동 로직(NIC_Cookie)에 대하여 기술한다. NIC_Cookie의 장점은 플러딩 공격 상태에서도 실시간으로 공격 패킷을 차단하고 정상적인 패킷만이 메인 CPU로 전달될 수 있도록 하기 때문에, 서버의 CPU 성능과 외부 네트워크의 구성 등에 영향을 받지 않는다는 것이다. 또한, 패킷 단위로 공격 TCP 세션에 대하여 실시간 차단 대응을 하기 때문에 정상적인 연결 시도에 대하여 잘못된 대응을 할 가능성이 없다. 이와 더불어, NCI_Cookie 로직 추가로 발생하는 지연시간은 패킷 길이와 상관없이 $7{\times}10^{-6}$초 이하의 성능을 보장하며, 본 논문에서는 구현된 NIC_Cookie가 일반적인 플러딩 공격을 실시간으로 방어하면서 그 성능을 보장함을 확인하였다.

• 한국산업융합학회 논문집
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• 제23권6_2호
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• pp.1043-1050
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• 2020

In this study, a study was presented on the monitoring technique of landslide area using UAV. In the case of disaster investigation using drone mapping, it can be used at various disaster sites. The mission can be carried out at various disaster sites, including surveys of damage to mountainous areas caused by landslides, building collapses surveys of flood damage, typhoons, earthquakes. The damage investigation plan using drone mapping is expected to be highly utilized at disaster sites where investigators cannot access it like in mountainous areas and where it is difficult to conduct direct damage investigations at the site. Drone mapping technology has many advantages in terms of disaster follow-up, such as recovery. Compared to the existing survey system, which was mainly carried out manually, the investigation time can be drastically reduced, and it can also respond to disaster sites that are difficult to carry out or are difficult to access directly. In addition, it is possible to establish and guide spatial data at the disaster site based on accurate mapping data from the time of the disaster, which has considerable strength in managing the situation of the disaster site, selecting priority areas for recovery, and establishing recovery plans. As such, drone mapping is a technology that can be used in a wide range of sites along with natural disasters and social disasters. If a damage investigation system is established through this, it is believed that it will contribute significantly to the rapid establishment of recovery plans along with the investigation of disaster response time and extent of damage recovery.

• 한국재난정보학회 논문집
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• 제16권1호
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• pp.123-132
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• 2020

연구목적: 초고층 건축물 지하공간 관련 법령, 국내외 지하공간 침수사례 및 침수 시뮬레이션으로 대피경로를 산정하여 초고층 건축물의 침수 대피 방안 도출을 위한 기초자료로 활용하고자 하였다. 연구방법: 초고층 건축물 지하공간 관련 법령 및 국내·외에서 발생한 지하공간 침수사례를 바탕으로 Test Bed를 활용한 침수 시뮬레이션을 실시하여 대피경로를 파악하였으며, 초고층 건축물에 대한 지하공간 침수가능성을 파악하였다. 연구결과: 위험도 레벨 4에 해당하는 지역이 존재함에도 침수위험도에 따른 대피경로의 변화는 없는 것으로 나타났다. 이는 대부분 대피 출발지점에서 위험도가 높아 기존 대피경로를 따라 이동하기 때문이며, 위험도가 적은지역이 시간이 지남에 따라 위험도가 높아져도 결국 그 지역을 신속히 지나야 대피장소로 갈 수 있기 때문에 경로 자체의 변화는 없는 것으로 판단된다. 결론: 본 연구에서는 침수위험도에 따른 대피경로의 차이가 없었으나, 건축물 별 지하공간의 규모와 형태가 상이한 경우, 시간에 따른 침수심의 변화가 다를 수 있을 것으로 판단된다. 특히, 침수심 변화에 따라 피난경로 또한 고정된 것이 아니라 안전하게 피난할 수 있는 경로가 변화할 수 있으므로 구체적인 피난경로에 대해서는 건축물에 따라 상세한 재분석이 요구될 것으로 사료된다.

• Journal of Ecology and Environment
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• 제34권2호
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• pp.175-191
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• 2011

Colonization patterns and community changes in benthic macroinvertebrates in the Cheonggye Stream, a functionally restored stream in downtown Seoul, Korea, were studied from November 2005 to November 2007. Benthic macroinvertebrates were quantitatively sampled 15 times from five sites in the stream section. Taxa richness (59 species in total) increased gradually over the first year, whereas the density revealed seasonal differences with significantly lower values in the winter season and after flood events. The benthic macroinvertebrate fauna may have drifted from the upstream reaches during floods and from the Han River, arrived aerially, or hitchhiked on artificially planted aquatic plants. Oligochaeta, Chironommidae, Psychodidae, and Hydropsychidae were identified as major community structure contributors in the stream. Swimmers and clingers colonized relatively earlier in the upper and middle reaches, whereas burrowers dominated particularly in the lower reaches. Collector-gatherers colonized at a relatively early period throughout the stream reaches, and collector-filterers, such as the net-spinning caddisfly (Cheumatopyche brevilineata), predominated in the upper and middle reaches after a 1-year time period. Cluster analyses and multi-response permutation procedures demonstrated that the Cheonggye Stream shares more similarities with the Jungnang Stream than with the Gapyeong Stream. Detrended correspondence analysis and nonmetric multidimensional scaling demonstrated that physical environmental factors (depth, current velocity, dissolved oxygen, and pH) as well as nutrients (total nitrogen and total phosphorous), water temperature, and conductivity could affect the distribution of benthic macroinvertebrates in the study streams.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권2호
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• pp.369-390
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• 2023

Technologies for disaster management are highly sought areas for research and commercial deployment. Landslides, Flood, cyclones, earthquakes, forest fires and road/train accidents are some causes of disasters. Capturing video and accessing data in real time from the disaster site can help first responders make split second decisions which may save human lives and valuable resource destructions. In this context the communication technologies performing the task should have high bandwidth and low latency which only 5G can deliver. But unfortunately in India, deployment of the 5G mobile communication systems is yet to give a shape and again in remote areas unavailability of 4G signals is still severe. In this situation the authors have proposed, simulated and experimented a 4G-5G communication scheme where from the disaster site the signals will be transmitted by a 5G terminal to a nearby 4G-5G gateway installed in a mobile vehicle. The received 5G signal will be further relayed by the 4G-5G gateway to the fixed 4G base station for onward transmission towards the disaster management station for decision making, deployment and relief monitoring. The 4G-5G gateway acts as a relay and converter of 5G signal to 4G signal and vice versa. This relayed system can be further mounted on a vehicle mounted relay (VMR) as proposed by 3GPP in Release 18. The scheme is also in the same line of context with Verizon's, "Tactical Humanitarian Operations Response" (THOR) vehicle concept. The performance of the link is studied in different channel conditions, the throughput achieved is superb. The authors have implemented the above mentioned system towards smart campus networking and monitoring landslides activities which are common in their regions.