• Journal of Positioning, Navigation, and Timing
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• 제1권1호
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• pp.7-14
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• 2012

Due to inaccurate safe navigation estimates, maritime accidents have been occurring consistently. In order to solve this, the precise positioning technology using carrier phase information is used, but due to high buildings near inland waterways or inclination, satellite signals might become weak or blocked for some time. Under this weak signal environment for some time, the GPS raw measurements become less accurate so that it is difficult to search and maintain the integer ambiguity of carrier phase. In this paper, a method to generate code and carrier phase measurements under this environment and maintain resilient navigation is proposed. In the weak signal environment, the position of the receiver is estimated using an inertial sensor, and with this information, the distance between the satellite and the receiver is calculated to generate code measurements using IGS product and model. And, the carrier phase measurements are generated based on the statistics for generating fractional phase. In order to verify the performance of the proposed method, the proposed method was compared for a fixed blocked time. It was confirmed that in case of a weak or blocked satellite signals for 1 to 5 minutes, the proposed method showed more improved results than the inertial navigation only, maintaining stable positioning accuracy within 1 m.

• Ecology and Resilient Infrastructure
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• 제3권3호
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• pp.156-161
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• 2016

세계적 기후변화 대응 관련하여, 도로분야에서는 국토교통부의 국가 R&D인 '탄소중립형 도로 기술개발' 연구단 과제가 수행되었고, 최근에는 지속가능한 발전이 다시 논의되고 있다. 연구단에서는 녹색도로 인증제 (안), 탄소저감형의 친환경 도로를 만들기 위한 녹색도로 설계와 시공 기술 개발, 도로에서의 탄소배출량을 산정하고 관리하기 위한 녹색도로기술 투자평가 시스템(G-TIES) 등이 개발되었다. 앞으로는 이들 기술의 적용 확대와 함께, 그 내용의 범위를 보다 확대한 지속가능의 개념을 고려하여 지속가능도로 시스템을 구축해 나가야 하며, 본 논문에서는 그 방안을 제안하였다.

• International Journal of Concrete Structures and Materials
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• 제1권1호
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• pp.63-73
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• 2007

Optimum multi-layered feed-forward neural network (NN) models using a resilient back-propagation algorithm and early stopping technique are built to predict the shear capacity of reinforced concrete deep and slender beams. The input layer neurons represent geometrical and material properties of reinforced concrete beams and the output layer produces the beam shear capacity. Training, validation and testing of the developed neural network have been achieved using 50%, 25%, and 25%, respectively, of a comprehensive database compiled from 631 deep and 549 slender beam specimens. The predictions obtained from the developed neural network models are in much better agreement with test results than those determined from shear provisions of different codes, such as KBCS, ACI 318-05, and EC2. The mean and standard deviation of the ratio between predicted using the neural network models and measured shear capacities are 1.02 and 0.18, respectively, for deep beams, and 1.04 and 0.17, respectively, for slender beams. In addition, the influence of different parameters on the shear capacity of reinforced concrete beams predicted by the developed neural network shows consistent agreement with those experimentally observed.

• International Journal of Concrete Structures and Materials
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• 제10권3호
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• pp.271-295
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• 2016

In this study, an extensive literature review has been conducted on the material characterization of UHPC and its potential for large-scale field applicability. The successful production of ultra-high performance concrete (UHPC) depends on its material ingredients and mixture proportioning, which leads to denser and relatively more homogenous particle packing. A database was compiled from various research and field studies around the world on the mechanical and durability performance of UHPC. It is shown that UHPC provides a viable and long-term solution for improved sustainable construction owing to its ultrahigh strength properties, improved fatigue behavior and very low porosity, leading to excellent resistance against aggressive environments. The literature review revealed that the curing regimes and fiber dosage are the main factors that control the mechanical and durability properties of UHPC. Currently, the applications of UHPC in construction are very limited due to its higher initial cost, lack of contractor experience and the absence of widely accepted design provisions. However, sustained research progress in producing UHPC using locally available materials under normal curing conditions should reduce its material cost. Current challenges regarding the implementation of UHPC in full-scale structures are highlighted. This study strives to assist engineers, consultants, contractors and other construction industry stakeholders to better understand the unique characteristics and capabilities of UHPC, which should demystify this resilient and sustainable construction material.

• 한국통신학회논문지
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• 제27권10C호
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• pp.902-911
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• 2002

무선 ad-hoc 네트워크는 어떠한 하부 구조와 중앙 관리의 도움 없이 임시 네트워크를 구성하는 무선 이동 호스트들의 집합이다. 무선 ad-hoc 네트워크는 빠르게 배치가능하고 변화에 탄력이 있어야 하는 네트워크 환경에 아주 유용하게 이용된다. 이러한 환경에서 분산 응용을 수행하기 위해서는 어느 정도 오류를 감내할 수 있는 강건한 구조가 요구되며, 또한 응용을 수행하는 데 사용되는 자원의 효율성도 요구된다. 본 논문에서는 무선 ad-hoc 네트워크 환경에서 강건하고 효율적으로 분산 응용이 수행될 수 있도록 강건한 신장 트리를 구성하고 유지하는 기법을 제안한다. 본 논문에서 제안하는 기법은 네트워크 위상의 변화에 영향을 적게 받는 강건한 신장 트리를 구성하기 위해 각 노드들간의 경로 정보를 이용하여 가장 결합도가 높은 경로를 우선적으로 선택하는 방식을 사용한다. 또한, 신장 트리를 효율적으로 유지하기 위해 네트워크 위상의 변화로 인해 신장 트리의 일부분의 붕괴되었을 때 처음부터 재구성하는 장식보다는 기존 신장 트리 정보를 이용하는 방식을 사용한다.

• Ecology and Resilient Infrastructure
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• 제2권2호
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• pp.161-166
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• 2015

최근 생태하천 복원 사업용으로 개발된 호안 공법에 대한 수리학적 설계기준이 부적절하여 이 공법이 적용된 하천에서 홍수기에 큰 경제적 손실을 유발하고 있다. 본 연구에서는 생태복원용으로 개발된 무독성 호안 블록을 실규모 수로에 설치하여 최고 유량 $3.0m^3/s$, 최고 유속 3.0 m/s에서 수리적 안정성을 평가하였다. 설치된 무독성 호안 블록은 실험 조건에서 상하 ${\pm}3mm$ 정도로 미미하게 이동하였다. 그러므로 실험에 적용한 무독성 호안 블록은 고유속에서 대규모 이동, 블록 파괴, 침상 침하 등이 나타나지 않는 것으로 보아 충분한 안정성을 확보한 것으로 판단되었다.

• 한국지진공학회논문집
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• 제27권2호
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• pp.91-99
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• 2023

Structural vibration induced by earthquake hazards is one of the most significant concerns in structure performance-based design. Structural hazards evoked from seismic events must be properly identified to make buildings resilient enough to withstand extreme earthquake loadings. To investigate the effects of combined earthquake-resistant systems, shear walls and five types of dampers are incorporated in nineteen structural models by altering their arrangements. All the building models were developed as per ACI 318-14 and ASCE 7-16. Seismic fragility curves were developed from the incremental dynamic analyses (IDA) performed by using seven sets of ground motions, and eventually, by following FEMA P695 provisions, the collapse margin ratio (CMR) was computed from the collapse curves. It is evident from the results that the seismic performance of the proposed combined shear wall-damper system is significantly better than the models equipped with shear walls only. The scrutinized dual seismic resisting system is expected to be applied practically to ensure a multi-level shield for tall structures in high seismic risk zones.

• 산경연구논집
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• 제14권8호
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• pp.9-17
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• 2023

Purpose: This study is to examine how modern art museums might develop into resilient, proactive, and adaptive enterprises. That implies that this study seeks to spur meaningful change by analyzing and comprehending the numerous facets of this issue, paving the path for a long-term future for contemporary art institutions worldwide. Research design, data and methodology: To achieve the purpose of this study, the current author has reviewed numerous relevant prior studies systemically. The technique used in this study was meticulously designed to guarantee accurate data collection and analysis, providing a thorough comprehension of the subject. An organized strategy was used, including finding, reviewing, and synthesizing earlier studies. Results: Based on the investigation of the current literature analysis, this study figured out four workable business models that might increase the prosperity of modern art museums. They result from a thorough examination of previous studies and these initiatives center on improving digital presence, enhancing community participation, diversifying revenue streams, and forming powerful alliances and partnerships. Conclusions: In sum, this study concludes that the use and integration of digital technology enable museums to reach a larger audience and open up opportunities for developing cutting-edge, interactive exhibitions that reflect modern patterns of participation and communication.

• 유통과학연구
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• 제22권4호
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• pp.69-77
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• 2024

Purpose: This paper aims to tackle the challenges and opportunities of cities' response to COVID-19 and provide cities with policy implications for better adapting to the post-pandemic era. Cities around the world are facing new challenges and have had to adapt to maintain social distancing measures while also addressing equity and social inclusion issues. Research design, data and methodology: The research methodology relies on an examination of existing literature, coupled with trend analysis employing discourse analysis to investigate post-pandemic urban resilience. The article also attempts to employ the concepts of adaptive urbanism and spatial flexibility and their potential to address these challenges not only in response to the pandemic, but also in the long-term. Results: The article explores the impact of COVID-19 on urban spatial structure through a public health lens and proposes actions that cities are able to take to enhance their resilience in the aftermath of the pandemic. Conclusions: It underscores the significance of reconstructing with improved distribution dynamics and provides valuable guidance for companies and policymakers on navigating these challenges. Ultimately, it also suggests that the pandemic has initiated a worldwide restructuring of urban planning, potentially leading to the emergence of smart cities grounded in science and technology.

• Structural Engineering and Mechanics
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• 제90권4호
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• pp.417-428
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• 2024

Nanocomposite-reinforced concrete systems have gained increasing attention in bridge construction due to their enhanced mechanical properties and durability. Understanding the transient dynamics of these advanced materials is crucial for ensuring the structural integrity and performance of bridge infrastructure under dynamic loading conditions. This paper presents a comprehensive study of the measurement techniques employed for assessing the transient dynamics of nanocompositereinforced concrete systems in bridge construction applications. A numerical method, including modal analysis are discussed in detail, highlighting their advantages, limitations, and applications. Additionally, recent advancements in sensor technologies, data acquisition systems, and signal processing techniques for capturing and analyzing transient responses are explored. The paper also addresses challenges and opportunities in the measurement of transient dynamics, such as the characterization of nanocomposite-reinforced concrete materials, the development of accurate numerical models, and the integration of advanced sensing technologies into bridge monitoring systems. Through a critical review of existing literature and case studies, this paper aims to provide insights into best practices and future directions for the measurement of transient dynamics in nanocompositereinforced concrete systems, ultimately contributing to the design, construction, and maintenance of resilient and sustainable bridge infrastructure.