• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.2 s.54
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• pp.129-136
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• 2009

The paper presents an algorithm of selecting optimal locations for measuring displacements(OLD) to adjust cable tension forces during the construction of cable-stayed bridges. The rank for optimal locations can be determined from the effective independence distribution vectors(EIDV) that are computed from the Fisher Information Matrices(FIM) formulated with the displacement sensitivities. To examine the efficiency and reliability of the proposed algorithm for determining OLD, a simulation study on a cable-stayed bridge has been carried out. The results using FIM formulated with displacements are compared with those using FIM with displacement sensitivities through the simulation study. The effects of measurement noise and error in cable length on the adjustment of cable tension forces are evaluated statistically by applying the Monte Carlo scheme.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.15-16
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• 2007

장기 송변전설비계획 수립 및 최적 계통운용을 위한 각종 검토업무를 위해서는 현재 운영중인 기설 전력계통 구성요소와 함께 향후 건설예정 설비의 전력계통 구성요소에 관한 제반자료가 필수적으로 소요되며, 이들 자료에 대한 정합성 및 통일성 유지가 매우 중요하다. 그러나 한국전력공사(이하 한전)에서는 이러한 자료가 활용목적 등의 차이로 인해 부서별로 관리대상이 다르며, 자료의 수집 및 관리업무가 전통적인 수작업 방식으로 이루어짐에 따라 업무 능률성, 자료갱신 적시성, 자료의 정확성 측면에서 개선해야할 과제로 여겨왔다. 본 논문에서는 최근 한전의 ERP(Enterprise Resource Planning, 전사적 자원관리) 구축과정에서 송변전설비 전력계통 구성요소 관리시스템을 구현함에 있어 단편적인 자료 관리기능이 아니라, 설비의 계획으로부터 건설, 운영, 폐기에 이르는 전 과정에 대해 PLM (Product Lifecycle Management, 수명주기관리)기법을 적용하여 해당분야에 획기적인 개선을 이룩한 사례를 기술하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.87-96
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• 2017

It is important to estimate the future maintenance budget of all SOC infrastructure at the national strategic level. In this study, Based on a currently available statistics data, we predicted future maintenance investment for all SOC infrastructure in Korea. We have studied the applicable prediction models, and we developed the prediction models that can calculated the future maintenance cost by a real expenditure date. The subjects of facilities are bridges, tunnels, pavements, harbors, dams, airports, water supply, rivers and port. As a result of total estimated cost, eight types of SOC infrastructures are about 23 trillion won for the next 10years, and the most expensive facilities are road pavements and bridges.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.349-353
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• 2006

국내에서도 최근 이상기후 현상이 빈번하게 발생하고 있고, 이로 인해 매년 봄가뭄과 여름홍수가 반복적으로 발생하여 효율적 수자원 관리의 중요성이 더욱 강조되고 있다. 최적 저수지 운영을 통한 효율적인 수자원 이용으로 과다한 무효 방류와 같이 낭비되는 수자원을 절감시켜 신규 수자원 개발과 유사한 효과를 획득하고, 기존 시설에 의한 지역 용수의 안정적인 공급으로 신규 수자원 개발 억제에 의한 비용 절감의 필요성과 유역의 수자원 변화를 평가하기 위한 모형의 개발이 필요하다. 본 연구에서는 저수량 확보, 생활.농업.공업.하천유지용수 공급, 홍수조절, 수력발전 등의 다양한 목적들을 적절히 고려하고, 사용자의 요구에 따라 목적별 우선권을 변경할 수 있도록 적절한 membership 함수를 구축하여 fuzzy DP 모형을 개발하였다. 또한, 개발된 fuzzy DP 모형에 소양강 다목적댐의 기왕의 수문자료를 도입한 모형의 최적화 운영결과와 기왕의 실적자료를 비교 검토하여 최적화 운영의 우수성을 확인하였다. 본 연구의 결과는 향후 저수지의 효율적인 운영을 위한 지침으로 사용될 수 있을 것이며, 유역의 수자원 영향 평가에 활용할 수 있을 것으로 기대된다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.765-778
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• 2008

Performance Profiles are essential to predict the performance variation over time for the bridge management system (BMS) based on risk management. In general, condition profiles based on experts opinion and/or visual inspection records have been used widely because obtaining profiles based on real performance is not easy. However, those condition profiles usually don't give a good consistency to the safety of bridges, causing practical problems for the effective bridge management. The accuracy of performance evaluation is directly related to the accuracy of BMS. The reliability of the evaluation is important to produce the optimal solution for distributing maintenance budget reasonably. However, conventional methods of bridge assessment are not suitable for a more sophisticated decision making procedure. In this study, a method to compute quantitative performance profiles has been proposed to overcome the limitations of those conventional models. In Bridge Management Systems, the main role of performance profiles is to compute and predict the performance of bridges subject to lifetime activities with uncertainty. Therefore, the computation time for obtaining an optimal maintenance scenario is closely related to the efficiency of the performance profile. In this study, the Response Surface Method (RSM) based on independent and important design variables is developed for the rapid computation. Steel box bridges have been investigated because the number of independent design variables can be reduced significantly due to the high dependency between design variables.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.77-83
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• 2016

Recently, interests for maintenance of transmission tower are increasing to extend life of structures and reduce maintenance cost. However, existing classical diagnosis method of corrosion deteriorated degree on the transmission tower steel members, visual inspection, has a problem that error often due to difference of inspector's individual knowledge and experience. In order to solve the problem, this study carried out to develop the corrosion deterioration inspection tool for transmission tower steel members. This tool is composed of camera equipment and computer-aided diagnosis system. We standardized the photographing method by camera equipment to obtain suitable pictures for image processing. Diagnosis system was designed to evaluate automatically degree of corrosion deterioration for member of transmission tower on the basis of the RGB color image processing techniques. It is anticipated that developed the corrosion deterioration inspection tool will be very helpful in decision of optimal maintenance time for transmission tower corrosion.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.2081-2091
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• 2013

Recently, the demand on the practical application of life-cycle cost effectiveness for design and rehabilitation of civil infrastructure is rapidly growing unprecedently in civil engineering practice. Accordingly, in the 21st century, it is almost obvious that life-cycle cost together with value engineering will become a new paradigm for all engineering decision problems in practice. However, in spite of impressive progress in the researches on the LCC, the most researches have only focused on the Deterministic or Probabilistic LCC analysis approach and general bridge at design stage. Thus, the goal of this study is to develop a practical and realistic methodology for the Life-Cycle Cost LCC-effective optimum decision-making based on reliability analysis of bridges at design stage. The proposed updated methodology is based on the concept of Life Cycle Performance(LCP) which is expressed as the sum of present value of expected direct/indirect maintenance costs with expected optimal maintenance scenario. The updated LCC methodology proposed in this study is applied to the optimum design problem of an actual highway bridge with Cable Stayed Bridges. In conclusion, based on the application of the proposed methods to an actual example bridge, it is demonstrated that a updated methodology for performance-based LCC analysis proposed in this thesis, shown applicably in practice as a efficient, practical, process LCC analysis method at design stage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.149-160
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• 2008

In this study, the research was carried out on how to identify the modal parameter by acquiring the output response of the structure only through the smart sensor system. The objective of this research is to verify the performance and the on-site adaptability of the smart sensor system that have been actively researched as the advanced measuring system so far. Smart Sensor System was developed so that the real-time dynamic measurement can be performed by means of MEMS-type accelerated sensor, 8 bit CPU, wireless MODEM. In the modal parameter identification test, random excitation was added to the cantilever beam, and then the response of the structure was obtained using the smart sensor system and the wire measurement system respectively. In analyzing the data, modal parameter was identified using NExT & ERA algorithm. Furthermore, the optimal measurement location was selected through EOT algorithm in order to obtain the qualified output response. Result of the test, it was possible to verify the on-site applicability of the smart sensor.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.4
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• pp.121-125
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• 2018

This paper presents the assessment of 7-wire strand monitoring using acoustic emission technique for bridges. 7-wire strand is widely used construction materials to provide additional tensile force to bridges. PSC (PreStressed Concrete) bridge and cable-stayed bridge are representatives for such cases. However, as the bridge aging progresses recently, corrosion problems of strand are emerging. For this reason, various NDT (Non-Destructive Test) methods for cable inspection are being studied and applied to the field. One of the NDT methods, acoustic emission technique, is known as an effective technique to detect cable damage and breakage. In this study, to evaluate the applicability of acoustic emission technique to bridges, acoustic emission signals according to damage of the strand were acquired and analyzed by tensile test. Moreover, The optimal AE sensor type was selected for field application. As a result, it is considered that the acoustic emission technique will be able to detect corrosion breakage and signs of rupture.

• Journal of Korean Society of Steel Construction
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• v.13 no.5
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• pp.467-476
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• 2001

The construction of highway bridges is almost complete in many countries including the United States. The government and highway agencies change the focus from constructing to maintaining To maintain the bridges effectively there is an urgent need to assess actual bridge loading carrying capacity and to predict their remaining life. The system reliability techniques have to be used for this purpose. Based on lifetime distribution (function) techniques this study illustrates how typical highway bridges can be modeled to predict their remaining life. The parameters of lifetime distribution are generated by Monte. The results can be used for optimization of planning interventions on existing bridges.