• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.117-118
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• 2009

A systematic procedure is proposed that can be used to assess the span of PSC girder bridge for a given condition. The proposed scheme adopts a graphical approach that represents a relationship between the number of prestressing tendons and the span, and is derived on a basis of safety assessment equations of the girder in each stage of fabrication and in service.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1490-1495
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• 2005

In this study, Model test of concrete frame structures with various shapes and locations are carried out by means of applying Peck's(1969) settlement method. The results of the model test indicated that important correlations existed between the behavior of frame structure and ground movement. Also, the damage level of frame structure closely influenced by the phase of excavation. Therefore, prediction of damage level at early phase of construction should be very precise. The damage level graph by Cording et al.(2001), the angular distortion provided gradually more serious damage to frame structures for the all cases. But the damage level graph by Burland(1997), was difficult to confirm because of very small amount of deflection ratio.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.04a
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• pp.37-43
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• 1990

This paper develops practical models and methods for the assessment of safety and rating of damaged and/or deteriorated bridges by incorporating a system identification technique for the explicit inclusion of the degree of deterioration or damage and of the actual bridge response. And, based on the proposed model, reliability-based rating methods are proposed as LRFR(Load and Resistance Factor Rating) and system reliability-index rating criteria. The proposed limit state model explicitly accounts for the degree of deterioration or damage in terms of the damage and response factors. The damage factor in the paper is proposed as the ratio of the current stiffness to the intact stiffness. Based on the observation and the results of applications to existing bridges, it may be concluded that the proposed rating models, which explicitly account for the uncertainties and the effects of degree of deterioration or damage based on the system identification technique, provide more realistic and consistent safety-assessment and capacity-rating.

• Research in Mathematical Education
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• v.23 no.1
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• pp.1-12
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• 2020

In this case study, a professor was observed to investigate use of instructional examples when teaching the Intermediate Value Theorem in a calculus course. Video-recorded lessons were analyzed with constant comparison to video-stimulated recall interviews and field notes. The professor employed multiple instructional examples, which was initiated by students and modified by the professor. The professor asked students to build non-existing examples as an informal proof of the Intermediate Value Theorem and assessment of students' previous knowledge. Use of incorrect examples on instructional purpose can be an appropriate way for formative assessment as well as a bridge between informal and formal proofs in college mathematics.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.629-632
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• 2008

Risk-based security impact evaluation may be affected by various factors according to numerous combinations of explosive devices, cutting devices, impact vehicles, and specific attack location to consider. Presently, in planning and design phases, designers are still often uncertain of their responsibility, lack of information and training of security. Therefore, designers are still failing to exploit the potential to reduce threats on site. In this study, the concept of security impact assessment is introduced in order to derive the performing design for safety in design phase. For this purpose, a framework for security impact assessment model using risk-based approach for bridge structures is suggested. The suggested model includes of information survey, classification of terror threats, and quantitative estimation of severity and occurrence.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.6
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• pp.483-500
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• 2007

Emerging sensor-based structural health monitoring (SHM) technology can play an important role in inspecting and securing the safety of aging civil infrastructure, a worldwide problem. However, implementation of SHM in civil infrastructure faces a significant challenge due to the lack of suitable sensors and reliable methods for interpreting sensor data. This paper reviews recent efforts and advances made in addressing this challenge, with example sensor hardware and software developed in the author's research center. It is proposed to integrate real-time continuous monitoring using on structure sensors for global structural integrity evaluation with targeted NDE inspection for local damage assessment.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.2
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• pp.1-10
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• 2024

Gimpo International Airport is only available for alternate airport for code F aircraft and it is difficult to operate larger aircraft capable of transporting more passengers than B747-400. This study has conducted to review the compatibility based on risk assessment to introduce the B747-8 operation procedures, excluding the A380 for practical reasons. Risk factors for main gear deviation when driving on curved sections of the taxiway was identified. The risk was analyzed as "high" level. As a risk reduction measure, the proceduralization of specific taxiing method "judgemental oversteer" was reviewed, and the result of the risk re-evaluation was lowered to a "low" level. As a result, the B747-8 was analyzed to be compatible. Additionally, It is suggested that review of pavement strength, de/anti-icing facilities, and passenger boarding bridge is necessary for actual operations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3451-3457
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• 2010

Cyber security assessment is the process of determining how effectively an entity being assessed meets specific cyber security objectives. Cyber security assessment helps to measure the degree of confidence one has and to identify that the managerial, technical and operational measures work as intended to protect the I&C systems and the information it processes. Recently, needs for cyber security on digitalized nuclear I&C systems are increased. However the overall cyber security program, including cyber security assessment, is not established on those systems. This paper presents the methodology of cyber security assessment which is appropriate for nuclear I&C systems. This methodology provides the qualitative assessments that may formulate recommendations to bridge the security risk gap through the incorporated criteria. This methodology may be useful to the nuclear organizations for assessing the weakness and strength of cyber security on nuclear I&C systems. It may be useful as an index to the developers, auditors, and regulators for reviewing the managerial, operational and technical cyber security controls, also.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.293-300
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• 2006

There is a high degree of uncertainty in measurements of the thickness or the loss of thickness of corroded elements. Generally the thickness of corroded elements varies from one location of the element to another depending on the degree of corrosion, which makes the safety assessment difficult. Therefore, a procedure for safety assessment of corrosion- damaged steel structures using an imprecise reliability is proposed in this paper. The proposed safety assessment procedure using the imprecise reliability was also applied to a cable-stayed bridge in Korea to demonstrate its effectiveness and applicability. Since there is a large variation in measurements of the thickness of corroded elements, the thickness of corroded elements was considered as the imprecise element. This variation was found to be directly related to the degree of corrosion. Therefore, the variation increases as the degree of corrosion increases. Based on the comparative observations between the conventional reliability and the imprecise reliability, it is suggested that the imprecise reliability analysis derived based on the subjective or statistical judgment of conditional independence could be successfully utilized for the risk or safety assessment of corrosion-damaged structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.139-148
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• 2008

The direct inspection of the outward aspects by field engineers is the important and critical part for structural safety assessment according to the related reports. This study presents an improved method of the state assessment for concrete floor slab by separating and evaluating the individual damage types. First, the various types of damage symptoms are separated, which have been included and dealt in a group. Secondly, they are weighted and scored independently based on the present guide and references. Overall procedures other than the above are retained as same as possible to avoid the confusion. The proposed method is applied and tested to a performed assessment project for a bridge for validation. The result shows that it is reasonable and applicable in respect that it is able to make up for the controversial points of the present guide revealed in practices. Careful check of excessively deteriorated parts in addition to the reasonable assessment of system by this method grants the structural repair and reinforcement propriety and economy, and assures of more safety. Twofold appraisal of this approach expands the applicable areas of value engineering to the structural maintenance.