• Geomechanics and Engineering
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• 제9권1호
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• pp.57-81
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• 2015

Water inrush and mud outburst always restricts the tunnel constructions in mountain area, which becomes a major geological barrier against the development of underground engineering. In view of the complex disaster-causing mechanism and difficult quantitative predictions of water inrush and mud outburst, several theoretical methods are adopted to realize dynamic assessment of water inrush in the progressive process of tunnel construction. Concerning both the geological condition and construction situation, eleven risk factors are quantitatively described and an assessment system is developed to evaluate the water inrush risk. In the static assessment, the weights of eight risk factors about the geological condition are determined using Analytic Hierarchy Process (AHP). Each factor is scored by experts and the synthesis scores are weighted. The risk level is ultimately determined based on the scoring outcome which is derived from the sum of products of weights and comprehensive scores. In the secondary assessment, the eight risk factors in static assessment and three factors about construction situation are quantitatively analyzed using fuzzy evaluation method. Subordinate levels and weight of factors are prepared and then used to calculate the comprehensive subordinate degree and risk level. In the dynamic assessment, the classical field of the eleven risk factors is normalized by using the extension evaluation method. From the input of the matter-element, weights of risk factors are determined and correlation analysis is carried out to determine the risk level. This system has been applied to the dynamic assessment of water inrush during construction of the Yuanliangshan tunnel of Yuhuai Railway. The assessment results are consistent with the actual excavation, which verifies the rationality and feasibility of the software. The developed system is believed capable to be back-up and applied for risk assessment of water inrush in the underground engineering construction.

• 한국건설관리학회논문집
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• 제12권2호
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• pp.89-100
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• 2011

사회간접자본(SOC)은 국가 산업부문과 국민경제에 매우 큰 영향을 끼치는 생산요소로 이에 대한 투자는 경제성장에 있어 필수적이며, 국가 경쟁력을 결정하는 주요 요소이다. 이러한 중요성을 인식하여 정부에서는 지난 1999년부터 예비타당성조사 제도를 도입하여 SOC 사업시행 유 무를 검토하고 있으나 과학적 투자평가방법의 미비, 조사 결과의 신뢰성 저하 등 근본적인 문제가 끊임없이 제기되고 있다. 이를 개선하고자 수행된 주요기관의 선행연구는 대부분 수요추정 및 경제성 분석 중심으로 진행되었고, 예비타당성조사의 주요 단계인 정책적 분석에 대한 연구진행은 아직 미흡한 실정이다. 이에 본 논문에서는 관련 학문과의 적절한 융합과 조화가 요구되는 (예비)타당성조사의 정책적 분석단계에 대하여 현행 전문가의 경험과 관련 자료에 의한 정성적 평가를 개선하고자 가치공학(VE)의 성능평가기법을 활용한 정량적 의사결정모델을 개발 제안하여 분석결과의 정량화를 유도하고 체계적 분석절차에 의한 전략적 판단도구로의 활용과 신규투자사업 목표에 대한 정책적 측면의 가치향상에 기여하고자 한다.

• Geomechanics and Engineering
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• 제8권5호
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• pp.631-647
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• 2015

Engineers may encounter unpredictable cavities, sinkholes and karst conduits while tunneling in karst area, and water inrush disaster frequently occurs and endanger the construction safety, resulting in huge casualties and economic loss. Therefore, an optimal classification method based on grey system theory (GST) is established and applied to accurately predict the occurrence probability of water inrush. Considering the weights of evaluation indices, an improved formula is applied to calculate the grey relational grade. Two evaluation indices systems are proposed for risk assessment of water inrush in design stage and construction stage, respectively, and the evaluation indices are quantitatively graded according to four risk grades. To verify the accuracy and feasibility of optimal classification method, comparisons of the evaluation results derived from the aforementioned method and attribute synthetic evaluation system are made. Furthermore, evaluation of engineering practice is carried through with the Xiakou Tunnel as a case study, and the evaluation result is generally in good agreement with the field-observed result. This risk assessment methodology provides a powerful tool with which engineers can systematically evaluate the risk of water inrush in karst tunnels.

• Smart Structures and Systems
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• 제5권3호
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• pp.223-240
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• 2009

As in any engineering application, the problem of structural assessment should face the different uncertainties present in real world. The main source of uncertainty in Health Monitoring System (HMS) applications are those related to the sensor accuracy, the theoretical models and the variability in structural parameters and applied loads. In present work, two methodologies have been developed to deal with these uncertainties in order to adopt reliable decisions related to the presence of damage. A simple example, a steel beam analysis, is considered in order to establish a liable comparison between them. Also, such methodologies are used with a developed structural assessment algorithm that consists in a direct and consistent comparison between sensor data and numerical model results, both affected by uncertainty. Such algorithm is applied to a simple concrete laboratory beam, tested till rupture, to show it feasibility and operational process. From these applications several conclusions are derived with a high value, regarding the final objective of the work, which is the implementation of this algorithm within a HMS, developed and applied into a prototype structure.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.72-76
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• 2015

Capital project benchmarking requires an effective cost normalization process to compare cost performance of projects accomplished in different time and location. Existing cost normalization approaches have been established based on the assumption that all required information for cost normalization is fully identified once a project is completed. Cost normalization, however, is sometimes required to evaluate phase-level outcomes of an ongoing project where the required information is not fully available. This paper aims to provide a cost normalization procedure for phase-based performance assessment. The procedure consists of three normalization steps: currency conversion, location adjustment, and time adjustment considering various scenarios where the required information is not fully identified. This paper also presents how the cost normalization procedure has been applied to the 10-10 Performance Assessment Program, which is a phase-based performance assessment system developed by the Construction Industry Institute (CII). Both researchers and industrial professionals can apply the cost normalization procedure to studies and practices regarding to cost estimation, feasibility analysis, and performance assessment.

• Nuclear Engineering and Technology
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• 제41권5호
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• pp.747-752
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• 2009

A vulnerability assessment is essential for the efficient operation of a physical protection system (PPS). Previous assessment codes have used a simple model called an adversary sequence diagram. In this study, the use of a two-dimensional (2D) map of a facility as a model for a PPS is suggested as an alternative approach. The analysis of a 2D model, however, consumes a lot of time. Accordingly, a generalized heuristic algorithm has been applied to address this issue. The proposed assessment method was implemented to a computer code; Systematic Analysis of physical Protection Effectiveness (SAPE). This code was applied to a variety of facilities and evaluated for feasibility by applying it to various facilities. To help upgrade a PPS, a sensitivity analysis of all protection elements along a chosen path is proposed. SAPE will help to accurately and intuitively assess a PPS.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.959-968
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• 2017

Electrical safety monitoring System (ESMS) is a critical component in modern power systems, which is characterized by large-scale access points, massive users and versatile requirements. For convenience of the information integration and analysis, the software development, maintenance, and application in the system, the cloud platform based ESMS is established and assessed in this paper. Firstly the framework of the system is proposed, and then the assessment scheme with a set of evaluation indices are presented, by which the appropriate cloud product can be chosen to meet the requirements of a specific application. Moreover, to calculate the weights of the evaluation indices under uncertainty, an improved interval AHP method is adopted to take into consideration of the fuzziness of expert scoring, the qualitative consistency test, and the two normalizations in the process of eigenvectors. Case studies have been made to verify the feasibility of the assessment approach for ESMS.

• 대한토목학회논문집
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• 제37권1호
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• pp.133-141
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• 2017

고속도로의 확충과 산업발전에 따른 물동량 증가로 인하여 도로 구조물의 내구성 저하와 취약구간의 반복적인 하자가 발생하고 있다. 따라서 국외에서 사용하는 품질보증제도 도입방안에 대한 연구가 진행되고 있다. 국내의 경우 한국도로공사는 점검위주의 품질관리에서 목적물의 품질성능 위주의 품질관리 체계로의 전환을 위하여 목적물의 품질 수준 측정이 가능하도록 정량적 평가 지수인 품질성능지수(QPI : Quality Performance Index)를 개발하여 적용하고 있다. 품질성능지수에서 콘크리트포장 평가인자는 포장두께, 압축강도, 평탄성, 기포간격계수로 구성되어 있다. 콘크리트 평가인자의 경우 국외에서 경험적 판단에 의해 자체적으로 선정된 인자를 사용하고 있는 실정이다. 따라서 본 연구에서는 콘크리트 포장 평가인자를 수명예측 시뮬레이션 및 실측 자료를 활용하여 분석하고 평가인자의 적정성을 검토하였다. QPI의 콘크리트포장 평가인자인 포장두께, 압축강도, 평탄성, 기포간격계수는 포장수명, 공용성 및 내구성을 적절하게 판단할 수 있는 인자로 사료된다.

• Nuclear Engineering and Technology
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• 제43권2호
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• pp.105-132
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• 2011

The concept of improved performance indicators (PIs) for use in the KINS Safety Performance Indicator (SPI) program for reactor safety area is proposed in this paper. To achieve this, the recently developed PIs from the USNRC that use risk information were investigated, and a feasibility study for the application of these PIs in Korean NPPs was performed. The investigated PIs are Baseline Risk Index for Initiating Events (BRIIE), Unplanned Scrams with Complications (USwC), and Mitigating System Performance Index (MSPI). Moreover, the thresholds of the existing safety performance indicators of KINS were evaluated in consideration of the risk and regulatory response to different levels of licensee performance in the graded inspection program.

• 설비공학논문집
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• 제25권11호
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• pp.600-605
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• 2013

Ground source heat pump systems (GSHP) can achieve higher performance of the system, by supplying more efficient heat source to the heat pump, than the conventional air-source heat pump system. But building clients and designers have hesitated to use GSHP systems, due to expensive initial cost, and uncertain economic feasibility. In order to reduce the initial cost, many researches have focused on the energy-pile system, using the structure of the building as a heat exchanger. Even though several experimental studies for the energy-pile system have been conducted, there was not enough data of quantitative evaluation with economic analysis and comprehensive analysis for the energy-pile. In this study, a prediction method has been developed for the energy pile system with barrette pile, using the ground heat transfer model and ground heat exchanger model. Moreover, a feasibility study for the energy pile system with barrette pile was conducted, by performance analysis and LCC assessment. As a result, it was found that the heat exchange rate of a barrette pile was 2.55 kW, and the payback period using LCC analysis was 8.8 years.