• 한국철도학회논문집
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• 제4권2호
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• pp.47-54
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• 2001

Railway companies have been faced with many changes in the railway environment. To cope immediately with the influence of environment and to improve productivity, an efficient train operation system and related core technologies must be introduced. The railway system is composed of large scale infrastructures and high-cost trains. Simulation method is one of core technologies and also efficient tool for planning and analyzing these kinds of complex system. In this research, we review basic simulation programming models and present a modeling for the elements of railway system such as rail-line infrastructure, train, time table and operational route. Additionally, some considerations on the development of multi-train traffic simulator for KyongBu-line are discussed.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.641-659
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• 2010

Structural Health Monitoring (SHM) gradually becomes a technique for ensuring the health and safety of civil infrastructures and is also an important approach for the research of the damage accumulation and disaster evolving characteristics of civil infrastructures. It is attracting prodigious research interests and the active development interests of scientists and engineers because a great number of civil infrastructures are planned and built every year in mainland China. In a SHM system the sheer number of accompanying wires, fiber optic cables, and other physical transmission medium is usually prohibitive, particularly for such structures as offshore platforms and long-span structures. Fortunately, with recent advances in technologies in sensing, wireless communication, and micro electro mechanical systems (MEMS), wireless sensor technique has been developing rapidly and is being used gradually in the SHM of civil engineering structures. In this paper, some recent advances in the research, development, and implementation of wireless sensors for the SHM of civil infrastructures in mainland China, especially in Dalian University of Technology (DUT) and Harbin Institute of Technology (HIT), are introduced. Firstly, a kind of wireless digital acceleration sensors for structural global monitoring is designed and validated in an offshore structure model. Secondly, wireless inclination sensor systems based on Frequency-hopping techniques are developed and applied successfully to swing monitoring of large-scale hook structures. Thirdly, wireless acquisition systems integrating with different sensing materials, such as Polyvinylidene Fluoride(PVDF), strain gauge, piezoresistive stress/strain sensors fabricated by using the nickel powder-filled cement-based composite, are proposed for structural local monitoring, and validating the characteristics of the above materials. Finally, solutions to the key problem of finite energy for wireless sensors networks are discussed, with future works also being introduced, for example, the wireless sensor networks powered by corrosion signal for corrosion monitoring and rapid diagnosis for large structures.

• Smart Structures and Systems
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• 제30권6호
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• pp.583-599
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• 2022

In this paper, a multi-objective wireless sensor network configuration optimization method is proposed. The proposed method aims to determine the optimal information and lifespan wireless sensor network for structural health monitoring of large-scale infrastructures. In particular, cluster-based wireless sensor networks with multi-type of sensors are considered. To optimize the lifetime of the wireless sensor network, a cluster-based network optimization algorithm that optimizes the arrangement of cluster heads and base station is developed. On the other hand, based on the Bayesian inference, the uncertainty of the estimated parameters can be quantified. The coefficient of variance of the estimated parameters can be obtained, which is utilized as a holistic measure to evaluate the estimation accuracy of sensor configurations with multi-type of sensors. The proposed method provides the optimal wireless sensor network configuration that satisfies the required estimation accuracy with the longest lifetime. The proposed method is illustrated by designing the optimal wireless sensor network configuration of a cable-stayed bridge and a space truss.

• 시큐리티연구
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• 제10호
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• pp.387-407
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• 2005

정보통신의 기술 발달로 인하여 국가안보와 직접적으로 관련된 국가사회의 주요인프라인 에너지 기반구조, 물류 기반구조, 금융 기반구조, 생활필수 기반구조가 상호 연결되면서 상호의존성이 크게 증가하고 있다. 국가기반구조가 정보통신 기반구조와 밀접하게 연결되면 다양한 정보서비스를 제공하는 긍정적인 측면과 더불어 새로운 위험요인을 내포하게 된다. 그러나 지금까지의 현대정보사회의 기술위험에 관한 논의는 원자력 사고, 화재, 교통재해, 가스안전사고 등 공중에게 직접적인 피해를 입히는 1차적 위험요소에 초점을 두고 있었던 반면, 그것 자체가 직접적인 위험요소는 아니지만 일단 사고가 발생하면 정보통신 기술의 발달로 인해 이루어진 국가기반구조 전반에 대한 운행(operation)을 저해하고 제반 위험관리기능을 마비시킴으로써 보다 광범위한 위험을 발생시킬 수 있는 제2차적인 위험요소에 대한 연구는 별로 없었다고 할 수 있다. 사회의 모든 부문에서 자동화와 정보화가 진행될수록 전기에 대한 의존이 커지는 이른 바 ‘전력화현상(electrification)'이 심화되고 있음을 감안할 때, 정보사회의 안보(安保)(security) 저해요소로서의 정전의 중요성이 갈수록 높아진다고 하겠다. 따라서 대규모 정전사태의 문제는 국가위기관리 차원에서 효과적으로 다루어야 하며 정보사회로의 진전이 급속도로 이루어질수록 대규모 정전사태에 대비한 관리체계가 매우 중요하다고 하겠다. 여기에서는 지금까지 발생한 대규모 정전사태의 사례를 분석하고 발생 원인을 심층적으로 살펴본 다음 한국의 정전관리체계를 국가위기관리 단계인 예방(완화 및 대비), 대응, 복구(보상) 단계에 대대 각각 조사해보았다. 결론에서는 보다 나은 효율적인 정전관리체계 수립을 위한 정책적 제안으로 전력의 안전공급체제 견지, 비상전원 설치에 대한 정책적 지원, 정전피해보상제도 개선 등을 제시하였다.

• 한국물환경학회지
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• 제33권2호
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• pp.160-169
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• 2017

The objective of this study are to analyze changes in future rainfall patterns in the Soyang-dam watershed according to the RCP 4.5 scenario of climate change. Second objective is to project peak flow and hourly sediment simulated for the future extreme rainfall events using the SWAT model. For these, accuracy of SWAT hourly simulation for the large scale watershed was evaluated in advance. The results of model calibration showed that simulated peak flow matched observation well with acceptable average relative error. The results of future rainfall pattern changes analysis indicated that extreme storm events will become more severe and frequent as climate change progresses. Especially, possibility of occurrence of large scale extreme storm events will be greater on the periods of 2030-2040 and 2050-2060. In addition, as shown in the SWAT hourly simulation for the future extreme storm events, more severe flood and turbid water can happen in the future compared with the most devastating storm event which occurred by the typhoon Ewiniar in 2006 year. Thus, countermeasures against future extreme storm event and turbid water are needed to cope with climate change.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.77-85
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• 2000

The railway system is composed of large scale infrastructures and high-cost trains. For planning and analyzing this kind of complex system, simulation method can be used for efficient tool. In this research, we review basic simulation programming models and present a modeling for the elements of railway system such as rail-line infrastructure, train, time table and operational route. Additionally, some considerations on the development of multi-train traffic simulator for KyongBu-line are discussed.

• KCI Concrete Journal
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• 제11권3호
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• pp.109-114
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• 1999

Recently the interest in the safety assessment of civil infrastructures has increased. As bridge structures become large-scale, it is necessary to monitor and maintain the safety of large bridges, which requires smart systems that can make long-term monitoring a reality . Civil engineers have applied monitoring systems to several bridges, such as the New Haeng-Ju Bridge and Riverside Urban Highway Bridge, but these applications have some problems with the sensors for long-term measurement, setup techniques for the bridge monitoring system and the assessment of measured data. In the present study, an optical fiber sensor smart system was tested and confirmed in laboratory tests on the concrete members. By Attaching optical fiber sensors to the structural parts of the Sung-San Bridge, the bridge load test was measured. These smart concrete structure systems can be applied to bridges and the load capacity of the bridge can assessed.

• Journal of Information Processing Systems
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• 제5권2호
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• pp.69-76
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• 2009

Self healing systems are considered as cognation-enabled sub form of fault tolerance system. But our experiments that we report in this paper show that self healing systems can be used for performance optimization, configuration management, access control management and bunch of other functions. The exponential complexity that results from interaction between autonomic systems and users (software and human users) has hindered the deployment and user of intelligent systems for a while now. We show that if that exceptional complexity is converted into self-growing knowledge (policies in our case), can make up for initial development cost of building an intelligent system. In this paper, we report the application of AHSEN (Autonomic Healing-based Self management Engine) to in OKKAM Project infrastructure backbone cluster that mimics the web service based architecture of u-Zone gateway infrastructure. The 'blind' load division on per-request bases is not optimal for distributed and performance hungry infrastructure such as OKKAM. The approach adopted assesses the active threads on the virtual machine and does resource estimates for active processes. The availability of a certain server is represented through worker modules at load server. Our simulation results on the OKKAM infrastructure show that the self healing significantly improves the performance and clearly demarcates the logical ambiguities in contemporary designs of self healing infrastructures proposed for large scale computing infrastructures.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.1017-1023
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• 2022

Past research shows that the construction of new infrastructure accelerates economic growth in the region by attracting more people and commodities. However, the previous studies only considered large-scale infrastructures such as sea-cross bridges and channel tunnels. There is a paucity of literature on regional infrastructure and its impact on socio-economic indicators. This paper explores the impact of new bridge construction on the human population, particularly focusing on regional bridges constructed during the 2000s in the state of Georgia. The human population at a county level was selected as a single socio-economic factor to be evaluated. A total of 124 cases were investigated as to whether the emergence of a new bridge affected the population change. The interrupted time series analysis was used to statistically examine the significance of population change due to the construction by treating each new bridge as an intervention event. The results show that, out of the 124 cases, the population of 67 cases significantly increased after the bridge construction, while the population of 57 cases was not affected by the construction at a significance level of 0.05. The 124 cases were also analyzed by route type, functional class, and traffic volume, but the results revealed, unlike large-scale infrastructure, that no clear evidence was found that a new bridge would bring an increase in the human population at a county level.

• 한국정보과학회논문지:시스템및이론
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• 제34권9호
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• pp.435-444
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• 2007

웹 페이지를 캐싱하는 것은 웹 하부 구조 상에서 중요한 역할을 한다. 캐싱 서비스의 효과는 제안된 대역폭을 가지는 무선 하부 구조 상에서 더욱 중요하게 여겨진다. 큰 규모의 하부 구조에서는 캐싱에서 발생할 수 있는 확장성과 요청 집중 현상(Hot-Spot) 문제를 해결하기 위해 서버들을 클러스터로 구성한다. 이에 본 논문에서는 무선 인터넷 프록시 서버 클러스터 환경에서 캐시 이용률 기반의 스케줄링 기법을 제안한다. 제안된 방법은 클라이언트의 요청을 캐시 서버 클러스터로 균일하게 분포시키고 요청 몰림 현상을 해결하기 위해 캐시 이용률을 이용하였다. 제안된 방법은 리눅스 클러스터 상에서 구현하였고, 실제로 사용되는 다양한 웹 traces들을 이용하여 실험을 수행하였다. 16대의 캐시 서버에서 수행된 실험결과는 제안된 해싱 기법이 요청 집중 현상을 해결하면서, 기존에 많이 사용되는 방법들에 비해 45%에서 114%까지 성능이 향상됨을 확인하였다.