• 한국안전학회지
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• 제37권6호
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• pp.148-157
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• 2022

Every year, particularly during the monsoon rainy season, landslides at the Chuncheon province of South Korea cause tremendous damage to lives, properties, and infrastructures. More so, the high rainfall intensity and long rainfall days that occurred in 2020 have increased the water content in the soil, thereby increasing the chances of landslide occurrences. Besides this, the rainfall thresholds and characteristics responsible for the initiation of landslides in this region have not been properly identified. Therefore, this paper addresses the rainfall thresholds responsible for the initiation of landslides at Chuncheon from a regional perspective. Using data obtained from rainfall measurements taken from 2002 to 2011, we identify a threshold relationship between rainfall intensity and rainfall duration for the initiation of landslides. In addition, we identify the relationship between the rainfall intensity using a 3-day, 7-day, and 10-day antecedent rainfall observation. Specifically, we estimate the rainfall data at 8 sites where debris flow occurred in 2011 by kriging. Following this, the estimated data are used to construct the relationship between the intensity (I), duration (D), and frequency (F) of rainfall. The results of the intensity-duration-frequency (IDF) analysis show that landslides will occur under a rainfall frequency below a 2-year return period at two areas in Chuncheon. These results will be effectively used to design structures that can prevent the occurrence of landslides in the future.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2020년도 학술발표회
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• pp.121-121
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• 2020

Varying dominant processes, including Tropical Cyclone (TC) and non-TC rainfall events, have been known to drive the occurrence of precipitation in South Korea. With the changes in the pattern of the Earth's climate due to anthropogenic activities, nonstationarity or changes in the magnitude and frequency of these dominant processes have been separately observed for the past decades and are expected to continue in the coming years. These changes often cause unprecedented hydrologic events such as extreme flooding which pose a greater risk to the society. This study aims to take into account a more reliable future climate condition with two dominant processes. Diverse statistical models including the hidden markov chain, K-nearest neighbor algorithm, and quantile mappings are utilized to mimic future rainfall events based on the recorded historical data with the consideration of the varying effects of TC and non-TC events. The data generated is then utilized to the hydrologic model to conduct a flood frequency analysis. Results in this study emphasize the need to consider the nonstationarity of design rainfalls to fully grasp the degree of future flooding events when designing urban water infrastructures.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.206-206
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• 2021

The necessity for appropriate management of water resources infrastructures such as reservoirs, levees, and dikes is increasing due to unexpected hydro-climate irregularities and rising water demands. To meet this need, past studies have focused on advancing theoretical optimization algorithms such as nonlinear programming, dynamic programming (DP), and genetic programming. Yet, the optimally derived theoretical solutions are limited to be directly implemented in making release decisions in the real-world systems for a variety of reasons. This study first aims to comparatively analyze the two prominent optimization methods, DP and evolutionary multi-objective direct policy search (EMODPS), under historical inflow series using K-fold cross validation. A total of six optimization models are formed each with a specific formulation. Then, one of the optimization models was coupled with the actual zone-based hedging rule that has been adopted in practice. The proposed methodology was applied to Boryeong Dam located in South Korea with conflicting objectives between supply and demand. As a result, the EMODPS models demonstrated a better performance than the DP models in terms of proximity to the ideal. Moreover, the incorporation of the real-world policy with the optimal solutions improved in all indices in terms of the supply side, while widening the range of the trade-off between frequency and magnitude measured in the sides of demand. The results from this study once again highlight the necessity of closing the gap between the theoretical solutions with the real-world implementable policies.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.145-145
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• 2021

Water distribution networks (WDNs) are designed to satisfy water requirement of an urban community. One of the central issues in human history is providing sufficient quality and quantity of water through WDNs. A WDN consists of a great number of pipelines with different ages, lengths, materials, and sizes in varying degrees of deterioration. The available annual budget for rehabilitation of these infrastructures only covers part of the network; thus it is important to manage the limited budget in the most cost-effective manner. In this study, a novel pipe replacement scheduling approach is proposed in order to smooth the annual investment time series based on a life cycle cost assessment. The proposed approach is applied to a real WDN currently operating in South Korea. The proposed scheduling plan considers both the annual budget limitation and the optimum investment on pipes' useful life. A non-dominated sorting genetic algorithm is used to solve a multi-objective optimization problem. Three decision-making objectives, including the minimum imposed LCC of the network, the minimum standard deviation of annual cost, and the minimum average age of the network, are considered to find optimal pipe replacement planning over long-term time period. The results indicate that the proposed scheduling structure provides efficient and cost-effective rehabilitation management of water network with consistent annual budget.

• Structural Monitoring and Maintenance
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• 제11권1호
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• pp.57-70
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• 2024

Masonry arch bridges as a vital infrastructure were not designed for seismic loads. Given that masonry arch bridges are made up of various components, their contribution under the seismic actions can be very undetermined and each of these structural components can play a different role in energy dissipation. Iran is known as a high-risk area in terms of seismic excitations and according to the seismic hazard zoning classification of Iran, most of these railway infrastructures are placed in the high and very high seismicity zones or constructed near the major faults. Besides, these ageing structures are deteriorated and thus in recent years, some of these bridges using various retrofitting approaches, including sprayed concrete technique are strengthened. Therefore, investigating the behavior of these restored structures with new characteristics is very significant. The aim of this study is to investigate the cyclic in-plane performance of masonry arch bridges retrofitted by sprayed concrete technique through the finite element simulation. So, by considering the fill-arch interaction, the nonlinear behavior of a bridge has been investigated. Finally, by extracting the hysteresis and enveloping curves of the retrofitted and non-retrofitted bridge, the effect of strengthening on energy absorption and degradation of material has been investigated.

• 국제학술발표논문집
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• The 10th International Conference on Construction Engineering and Project Management
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• pp.247-254
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• 2024

To enhance the overall well-being of individuals, acquiring only a quantitative inventory of the individual infrastructure is insufficient and comprehending public perspectives on service levels and infrastructure needs is equally important. This study presents a model for infrastructure service quality that considers the various needs of residents. The study examined the significance and appropriateness of infrastructure service indices in determining the priorities and objectives of government investment in infrastructures. The primary objective was to construct and authenticate a multidimensional model of infrastructure service quality, building on the SERVQUAL framework established in 1988. A survey was distributed to individuals residing in Korea, and 12,500 completed questionnaires were collected. In this study, we conduct a path analysis to test our hypotheses using the AMOS software (version 29.0). The findings of the study indicate that residential satisfaction has a considerable impact on the quality of life. Additionally, this study indicates that the level of infrastructure performance in a residential area has a substantial impact on people's satisfaction with their housing. Furthermore, the findings indicate that it is crucial to address both the quantitative and qualitative dimensions of infrastructure simultaneously. Finally, the evaluation of the efficacy of infrastructure enhancement investments should consider the quality of the infrastructure services.

• 비파괴검사학회지
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• 제28권2호
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• pp.164-176
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• 2008

기존 사회기반 시설의 안전성 평가를 위해서는, 콘크리트 부재에 존재하는 균열에 대해 정량적인 평가가 필요하다. 이 논문에서는 균열의 깊이를 측정할 수 있는 비파괴검사 중 표면파 투과기법에 대해 고찰하였다. 특히, 콘크리트 부재 내부에 위치하는 철근이 표면파에 미치는 영향을 분석하여, 표면파 투과기법을 통한 균열깊이 추정 시 철근에 의해 발생하는 오차가 크지 않음을 확인하였다. 또한, 콘크리트 부재의 형상에 따라 발생하는 여러 반사파의 영향을 최소화하기 위해 치적의 윈도우 크기를 제안하여 그 타당성을 검증하였다.

• 한국재난관리표준학회지
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• 제2권4호
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• pp.67-73
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• 2009

사회기반시설은 국가 경제 활동의 기반을 형성하는 기초적인 시설이기 때문에 교량붕괴와 같은 예상치 못한 구조물 이상은 개인 및 국가적인 경제적 손실을 발생시킬 뿐만 아니라 사회문제로까지 확대될 수 있다. 따라서 사회기반시설을 이루는 구조물에 대한 지속적인 유지관리와 안전관리는 비중 있게 다루어져야 한다. 교량 유지관리를 위한 모니터링은 90년대 초에 처음 도입되어 현재는 실시간 계측과 분석이 가능한 상태로까지 발전하였으며 최근에는 첨단센서를 이용한 시스템이 개발되고 있다. 본 논문에서는 상기와 같은 모니터링 시스템을 구축함에 있어서 최근 주목받고 있는 광섬유 센서를 이용하는 경우의 경제성을 알아보기 위해 다양한 조건에 대한 비용 분석을 실시하였다. 또한 분석결과를 현재 널리 사용되고 있는 전기저항식 센서를 이용하여 모니터링 시스템을 구축하는 경우와 비교하여 광섬유 센서를 이용한 교량 모니터링 시스템의 경제성을 살펴보았다. 검토결과 광섬유 센서를 사용하여 모니터링 시스템을 구축하는 경우 많은 부분 기존의 경우보다 보다 나은 이점을 취할 수 있고 비용 측면에서도 경쟁력을 가질 수 있음을 알 수 있었다.

• Structural Engineering and Mechanics
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• 제63권2호
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• pp.147-160
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• 2017

In this study, the optimum parameters of Tuned Mass Dampers (TMDs) are proposed using Gravity Search Algorithm (GSA) and Particle Swarm Optimization (PSO) to reduce the responses of the structures. A MATLAB program is developed to apply the new approach to the benchmark 10 and 40-story structures. The obtained results are compared to those of other optimization methods used in the literature to verify the developed code. To show the efficiency and accuracy of the proposed methods, nine far-field and near-field worldwide earthquakes are applied to the structures. The results reveal that in the 40-story structure, GSA algorithm can reduce the Relative Displacement (RD) and Absolute Acceleration (AA) up to 43% and 21%, respectively while the PSO decreases them by 50% and 25%, respectively. In contrast, both GSA and PSO algorithms reduce the RD and AA about 29% and 21% for the 10-story structure. Furthermore, using the proposed approach the required TMD parameters reduce by 47% and 63% in the 40 and 10-story buildings in comparison with the referenced ones. Result evaluation and related comparison indicate that these methods are more effective even by using smaller TMD parameters resulting in the reduction of acting force from TMD, having smaller stiffness and damping factors while being more cost effective due to its decreased parameters. In other words, the TMD with optimum parameters can play a positive role in both tall and typical structures.

• 한국구조물진단유지관리공학회 논문집
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• 제17권6호
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• pp.153-161
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• 2013

본 논문은 토목 시설물의 유지관리 분야에서 BIM을 도입하기 위해 필요한 핵심 표준화 항목과 그 추진 방안을 제시한다. 이를 위해 시설물의 유지관리에 관한 가치사슬과 BIM의 기술적 특성을 분석하여 가치사슬 상에서 최초로 수행되는 손상정보의 기록 방식이 BIM의 정보운용 방식과 매우 유사함을 밝혔다. 또한 시설물 유지관리 가치사슬 단계별로 수행되는 업무에 부합되는 BIM 데이터를 생산하고 운영하기 위해 필요한 표준화 항목을 제시하였다. 제시된 표준화 항목은 시설물의 전 생애주기에서 공통으로 적용되는 표준과 시설물 유지관리 목적에 맞추어 특화된 표준화 항목으로 구분하였으며, 각 구분된 항목에 대하여 표준화 추진 시 중심 역할을 수행할 수 있는 기관을 법령에 근거하여 제시하였다.