• Geomechanics and Engineering
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• 제25권2호
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• pp.135-142
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• 2021

This study provided a new research perspective for processing and analyzing AE data to evaluate rock failure. Cluster method and information entropy theory were introduced to investigate temporal and spatial correlation of acoustic emission (AE) events during the rock failure process. Laboratory experiments of granite subjected to compression were carried out, accompanied by real-time acoustic emission monitoring. The cumulative length and dip angle curves of single links were fitted by different distribution models and distribution functions of link length and directionality were determined. Spatial scale and directionality of AE event distribution, which are characterized by two parameters, i.e., spatial correlation length and spatial correlation directionality, were studied with the normalized applied stress. The entropies of link length and link directionality were also discussed. The results show that the distribution of accumulative link length and directionality obeys Weibull distribution. Spatial correlation length shows an upward trend preceding rock failure, while there are no remarkable upward or downward trends in spatial correlation directionality. There are obvious downward trends in entropies of link length and directionality. This research could enrich mathematical methods for processing AE data and facilitate the early-warning of rock failure-related geological disasters.

• Structural Engineering and Mechanics
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• 제68권6호
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• pp.677-689
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• 2018

Residual deformation is a crucial index that should be paid special attention in the performance-based seismic analyses of reinforced concrete (RC) structures. Owing to their superior re-centering capacity under earthquake excitations, the post-tensioned self-centering (PTSC) RC frames have been proposed and developed for engineering application during the past few decades. This paper presents a comprehensive assessment on the seismic fragility of a PTSC frame by simultaneously considering maximum and residual deformations. Bivariate limit states are defined according to the pushover analyses for maximum deformations and empirical judgments for residual deformations. Incremental Dynamic Analyses (IDA) are conducted to derive the probability of exceeding predefined limit states at specific ground motion intensities. Seismic performance of the PTSC frame is compared with that of a conventional monolithic RC frame. The results show that, taking a synthetical consideration of maximum and residual deformations, the PTSC frame surpasses the monolithic frame in resisting most damage states, but is more vulnerable to ground motions with large intensities.

• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1387-1401
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• 2018

An aircraft impact (AI) on a nuclear power plant (NPP) is considered to be a beyond-design-basis event that draws considerable attention in the nuclear field. As some NPPs have already adopted the seismic isolation technology, and there are relevant standards to guide the application of this technology in future NPPs, a new challenge is that nuclear power engineers have to determine a reasonable method for performing AI analysis of base-isolated NPPs. Hence, dynamic influences of the seismic isolation on the vibration and structural damage characteristics of the base-isolated CPR1000 containment are studied under various aircraft loads. Unlike the seismic case, the impact energy of AI is directly impacting on the superstructure. Under the coupled influence of the seismic isolation and the various AI load, the flexible isolation layer weakens the constraint function of the foundation on the superstructure, the results show that the seismic isolation bearings will produce a large horizontal deformation if the AI load is large enough, the acceleration response at the base-mat will also be significantly affected by the different horizontal stiffness of the isolation bearing. These concerns require consideration during the design of the seismic isolation system.

• 한국해안·해양공학회논문집
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• 제33권6호
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• pp.293-297
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• 2021

소파블록 피복제 제체의 한계상태설계법 개발을 위해 하중저항계수 보정을 수행하였다. 실제 시공된 소파블록 피복제 제체의 설계자료를 분석하여 신뢰성해석을 수행하였으며 목표신뢰성지수에 따른 부분안전계수와 하중, 저항계수를 차례로 산정하였다. 최적화기법을 통해 한계상태설계법 개발을 위한 하중계수와 저항계수를 도출하였다. 최종 하중저항계수를 이용하여 방파제를 재설계하였으며 목표수준의 신뢰성지수를 상회하는지 검증하였다. 해외기준의 하중저항계수와 본 연구에서 구한 하중저항계수를 비교하였다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2005년도 춘계학술발표회
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• pp.195-208
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• 2005

선박은 전통적으로 국제법상 기국주의 원칙이 적용되어 기국정부가 선박의 통제 및 관할권을 행사하여 왔으나 국제적으로 기준미달선이 자주 출현하여 부당한 해운서비스를 제공하고 특히, 외국연안에서 해양오염사고를 일으킴에 따라 항만국들이 자국의 이익보호를 위해 외국적의 기준미달선에 대한 통제를 강화하고 있다. 따라서 항만국통제제도는 기국에 대해서는 책임의 문제이고 항만국으로서는 권한이라고도 할 수 있는데 보다 더 큰 의미로 한다면 기준미달선을 제거함으로써 해상안전과 해양오염방지를 보장하려는 항만국과 기국의 협력체제라고 할 수 있다. 그런데 해상안전과 해양환경보호를 위하여 기항지국에 의한 항만국통제 행위가 아무리 정당한 행위라 할지라도 국제규칙을 잘못 적용하거나 항만만국통제관의 권한을 일탈한 통제행위를 한 경우 국제적 분쟁을 야기시킬 수 있다. 따라서 본 연구에서는 항만국통제의 법적근거를 국제협약과 국내해사법에서 알아보고, 이를 기초로 항만국통제관이 통제제도를 국내적으로 실시함에 있어서 제기될 수 있는 국제법과 국내법과의 충돌문제를 다룬다.

• 한국항해항만학회지
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• 제27권3호
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• pp.329-333
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• 2003

Study of the background and state of Osaka's waterfront space development and analysis of the functions of 22 chosen major facilities of development project reveals the following four types: amenity-oriented development, large-scale synthesis type development, renewal compound area type development, exchange communication promotion type development. Osaka bay area has served primely as the base of harbors, industry and energy, while analysis of the ongoing project has found that the city has been making a functional transition to a type of development to live up to the needs of the times, suggesting that is wise that Korea's future direction of waterfront development be oriented toward environmental-friendly development by taking advantage of low-density area's natural resources. Given the plurality and complexity of the law of coastal zone, what is needed is a legal maintenance for coastal zone's clear-cut coordinating function and for environmental-friendly development with the limitations of seaside and coastal functions in mind.

• 농촌계획
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• 제4권2호
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• pp.70-78
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• 1998

The objective of this study was to enforce systematic evaluation on the present condition and ecosystem of coastal wetland to use frame of environmental indicators, For this, the indicators for evaluation of coastal wetland were established and were applied to the present condition. Then, the application possibility of this evaluation indicators and management method by group of coastal method are presented. These results present the following consideration in case that the ideal management method on the conservation and development of coastal wetlands was proposed. In case of Kang-hwa island which had the good natural environment, the mlnimum development with maintenance of the present state must be driven. In case of Tae-an which had the good natural environment and development potential, the development that was in harmony with the nature must to be driven. In case of Seo-chon which was previously developed region, the various development programs which had the minimum effects on the natural, living and socio $.$ economic environment must to be provided.

• 한국환경독성학회:학술대회논문집
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• 한국환경독성학회 2004년도 Sharing Experience of Human and Ecological Risk Assessment and Management in Asia/Pacific Region
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• pp.49-50
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• 2004

• Nuclear Engineering and Technology
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• 제55권3호
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• pp.968-980
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• 2023

The dynamic structural responses are sensitive to the time-frequency content of seismic waves, and seismic input motions in time-history analysis are usually required to be compatible with design response spectra according to nuclear codes. In order to generate spectra-compatible input motions while maintaining the intrinsic non-stationarity of seismic waves, an improved time-domain approach is proposed in this paper. To maintain the nonstationary characteristics of the given seismic waves, a new time-frequency envelope function is constructed using the Hilbert amplitude spectrum. Based on the intrinsic mode functions (IMFs) obtained from given seismic waves through variational mode decomposition, a new corrective time history is constructed to locally modify the given seismic waves. The proposed corrective time history and time-frequency envelope function are unique for each earthquake records as they are extracted from the given seismic waves. In addition, a dimension reduction iterative technique is presented herein to simultaneously superimpose corrective time histories of all the damping ratios at a specific frequency in the time domain according to optimal weights, which are found by the genetic algorithm (GA). Examples are presented to show the capability of the proposed approach in generating spectra-compatible time histories, especially in maintaining the nonstationary characteristics of seismic records. And numerical results reveal that the modified time histories generated by the proposed method can obtain similar dynamic behaviors of AP1000 nuclear power plant with the natural seismic records. Thus, the proposed method can be efficiently used in the design practices.

• Spatial Information Research
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• 제22권2호
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• pp.63-71
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• 2014

최근 해양레포츠 산업이 블루오션으로 떠오르고 있는데, 해양레포츠는 조류, 수온, 염도 등과 같은 다양한 환경조건에 영향을 받기 때문에 관측자료 뿐만 아니라 모델 예측자료도 매우 필요한 정보이다. 본 연구에서는 연안해양모델인 FVCOM(Finite Volume Coastal Ocean Model)에서 산출된 예측자료를 웹 및 스마트폰을 통해 제공하는 시각화시스템을 구현하였다. 이를 위하여 FVCOM 자료에 내삽과 샘플링 등의 전처리를 하여, 조위, 수온, 염도의 래스터 이미지와 조류(유속, 유향)의 벡터 데이터베이스를 구축하였고, 스프링 프레임워크(Spring Framework)를 활용하여 REST(Representational State Transfer) 기반의 API(Application Programming Interface)를 제공하는 웹서비스를 구축하였다. 또한 데이터베이스 자료를 데스크톱 및 이기종의 스마트폰에 탑재시킴으로써 크로스플랫폼(cross-platform) 시각화 환경을 실현하였다.