• Smart Structures and Systems
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• 제1권4호
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• pp.355-368
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• 2005

Large and complex structures are being built now-a-days and, they are required to be functional even under extreme loading and environmental conditions. In order to meet the safety and maintenance demands, there is a need to build sensors integrated structural system, which can sense and provide necessary information about the structural response to complex loading and environment. Sophisticated tools have been developed for the design and construction of civil engineering structures. However, very little has been accomplished in the area of monitoring and rehabilitation. The employment of appropriate sensor is therefore crucial, and efforts must be directed towards non-destructive testing techniques that remain functional throughout the life of the structure. Fiber optic sensors are emerging as a superior non-destructive tool for evaluating the health of civil engineering structures. Flexibility, small in size and corrosion resistance of optical fibers allow them to be directly embedded in concrete structures. The inherent advantages of fiber optic sensors over conventional sensors include high resolution, ability to work in difficult environment, immunity from electromagnetic interference, large band width of signal, low noise and high sensitivity. This paper brings out the potential and current status of technology of fiber optic sensors for civil engineering applications. The importance of employing fiber optic sensors for health monitoring of civil engineering structures has been highlighted. Details of laboratory studies carried out on fiber optic strain sensors to assess their suitability for civil engineering applications are also covered.

• 전산구조공학
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• 제7권1호
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• pp.109-116
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• 1994

구조물의 신뢰도를 평가하는 방법을 살표보고 각각의 장.단점을 비교한다. 각 방법의 정확성을 평가하는 기준으로는 Crude Monte Carlo(CMC)방법을 택하여 Importance Sampling(IS)방법, 그리고 Directional Simulation(DS) 방법을 살펴보고 1차 근사방법은 현재 많이 사용되고 있는 Rackwitz-Fiessler(RF)방법, Chen과 Lind가 제안한 3-parameter방법(CL), Hohenbichler가 제안한 Rosenblatt 변환방법(RT)을 그리고 2차 근사방법은 Breitung이 제안한 곡률적합 포물선 (Curvature Fitted Paraboloid, CFP) 공식과 Kiureghian이 제안한 점적합 포물선(Point Fitted Paraboloid, PFP)공식, 그리고 Log-Likelihood Function을 이용하여 원변수공간에서 파괴확률을 구하는 2차 근사공식(LLF)을 비교한다. 그리고 한계상태식이 불명확할 때 효율적으로 사용할 수 있는 반응응답법(Response sufrace method, RSM)을 살펴본다. 각 방법의 효율성 특히 적용 가능성을 예제를 통해 해석한 결과 추출법의 경우는 DS방법이, 그리고 근사방법에서는 RSM방법이 효율적임을 알 수 있다.

• 한국구조물진단유지관리공학회 논문집
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• 제25권1호
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• pp.51-58
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• 2021

2014년 수직증축형 리모델링 제도가 시행됨에 따라, 수직 증축과정에서 발생 가능한 구조 안전에 대한 문제 해결을 위해 증축형 리모델링 안전진단 매뉴얼이 제정되었다. 이 매뉴얼에서 내하력 평가를 위한 층별 가중치 부분은 재건축 안전진단 매뉴얼을 인용하였으나, 공학적 근거가 다소 미흡하다. 또한, 수직증축형 리모델링에서 내하력 평가의 중요도가 재건축에서보다 높으므로 층별 가중치 산정 방법의 개선이 필요하다. 따라서 본 연구에서는 층별 가중치에 대한 공학적 근거를 마련하고자 기존 매뉴얼 및 지침 분석을 통해 층별 중요도와 층별 가중치를 정의하였으며, 역학적 원리를 바탕으로 합리적인 가중치 산정식을 제시하였다.

• 수산해양기술연구
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• 제59권1호
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• pp.85-98
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• 2023

This study analyzes the importance and implementation of countermeasures to reduce safety accidents that may occur during fishing in coastal gillnet fishing. Safety accidents that may occur in coastal gillnet fishing were classified into 56 measurement items in six areas: slips and trips, contact with machinery, falls, struck by object, musculoskeletal symptoms, and electrical shock. 35 fishermen belonging to coastal gillnet associations in Tongyeong and Namhae were selected as samples, and the importance and implementation of the proposed measurement items were investigated in the field. In addition, the results were evaluated visually by IPA analysis. As a result of the analysis, the importance of struck by object was the highest, and the implementation of slips and trips was the highest. On the other hand, prevention of musculoskeletal damage was found to be the lowest in both importance and implementation. The area with the most significant difference in importance and implementation by the classified area for measurement items was struck by object, and the area with the minor difference was slips and trips. Among the measurement items, the importance is highly recognized, but there are items with low implementation. To improve their level of implementation, countermeasures such as continuous education, economic support, and structural change of fishing boats should be prepared; moreover, policy support activities for implementation should be carried out.

• 한국전산구조공학회논문집
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• 제23권4호
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• pp.425-434
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• 2010

본 연구에서는 고층건물 구조시스템의 다양한 대안으로부터 이들의 성능을 합리적으로 평가하는 방안을 제안하였다. 대안평가는 업무절차에 따라 예비평가, 본평가, 실시평가로 나누어 수행된다. 대안평가를 위한 평가범주는 구조성능, 경제성, 공기의 세 가지로 구성되고, 각 평가범주는 이들을 평가하기 위한 세부 평가항목으로 구성된다. 예비평가에서는 경험지식에 의한 정성적인 평가를 수행하며, 본평가와 실시평가에서는 수치적인 결과를 바탕으로 주로 정량적인 평가를 수행한다. 평가결과의 종합화는 평가항목들간의 관계가 선형적이라는 가정하에 가중평균법을 적용하였다. 제안된 대안평가 방안은 실무예제에 대한 시뮬레이션을 통하여 그 적용성을 검토하였다.

• Structural Engineering and Mechanics
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• 제56권4호
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• pp.695-705
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• 2015

Distressed structures require necessary remedial measures in order to restore their original structural properties like strength and stiffness. Validating the effectiveness of the proposed qualitative remedial measure experimentally is of utmost importance as there is no well-established analytical method to verify the effectiveness of the same quantitatively. Prototype testing which would have been the best option for this purpose would not only prove costly but also be associated with numerous practical difficulties; hence model testing is resorted as the only option for the purpose. This paper presents one such typical experimental study on the structural behavior of a distressed bridge, mainly observed in the form of prominent tilt in the bearing plate in transverse and longitudinal direction on downstream side. The main focus of the proposed experimental investigation is to assess the structural behavior particularly the load carrying capacity. The extent of deformation of some models with specific structural arrangements and some models with specific need based remedial measures were also studied. This study also assessed the contribution of each remedial measure towards restoration individually and collectively.

• Structural Engineering and Mechanics
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• 제76권2호
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• pp.193-205
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• 2020

The growing need for assuring efficient and sustainable investments in civil engineering structures has determined a renovated interest in the rational design of such structures from designers, clients and authorities. As a result, risk-informed decision-making methodologies are increasingly being used as a direct decision tool or as an upper-level layer from which performance-based approaches are then calibrated against. One of the most important and challenging aspects of today's structural design is to adequately handle the system-level effects, the known unknowns and the unknown unknowns. These aspects revolve around assessing and evaluating relevant damage scenarios, namely those involving unacceptable/intolerable damage levels. Hence, the importance of risk analysis of disproportionate collapse, and along with it of robustness. However, the way robustness has been used in modern design codes varies substantially, from simple provisions of prescriptive rules to complex risk analysis of the disproportionate collapse. As a result, implementing design for robustness is still very much a grey area and more so when it comes to defining means to quantify robustness. This paper revisits the most common robustness frameworks, highlighting their merits and limitations, and identifies one among them which is very promising as a way forward to solve the still open challenges.

• Smart Structures and Systems
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• 제2권3호
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• pp.253-274
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• 2006

The structural monitoring of multi-wire strands is of importance to prestressed concrete structures and cable-stayed or suspension bridges. This paper addresses the monitoring of strands by ultrasonic guided waves with emphasis on the signal processing and automatic defect classification. The detection of notch-like defects in the strands is based on the reflections of guided waves that are excited and detected by magnetostrictive ultrasonic transducers. The Discrete Wavelet Transform was used to extract damage-sensitive features from the detected signals and to construct a multi-dimensional Damage Index vector. The Damage Index vector was then fed to an Artificial Neural Network to provide the automatic classification of (a) the size of the notch and (b) the location of the notch from the receiving sensor. Following an optimization study of the network, it was determined that five damage-sensitive features provided the best defect classification performance with an overall success rate of 90.8%. It was thus demonstrated that the wavelet-based multidimensional analysis can provide excellent classification performance for notch-type defects in strands.

• 한국신뢰성학회지:신뢰성응용연구
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• 제6권3호
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• pp.213-224
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• 2006

Social capital contains relational, structural and cognitive dimensions. This study regards social capital as diminishing factor in innovation resistance. Trust, structuring individual tie and vision sharing which are representatives of three dimensions of social capital diminish innovation resistance. So innovation becomes more successful.

• 경영과정보연구
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• 제39권3호
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• pp.99-125
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• 2020

본 연구는 계층분석법(Analytic Hierarchy Process, AHP)을 활용하여 우리나라 굴 산업에 있어 정부의 정책 우선순위를 결정하고, 중요도와 만족도를 고려한 굴 산업 발전을 위한 정부정책지원 방안을 제안하고자 한다. 또한 본 연구는 AHP를 활용하여 정부의 굴 산업 지원정책의 중요도에 따른 우선순위를 결정하고, 이를 활용한 직·간접종사자의 만족도를 비교하여 우리나라 굴 산업 발전을 제고할 수 있는 정책지원방향을 제안함으로써 굴 산업 발전에 기여하고자 한다. AHP 분석에 의한 중요도 분석결과는 중요도에 있어 전체 표본을 대상으로 평가한 결과 경쟁력강화의 생산공급의 생산시설, 경쟁력강화의 생산공급의 원료구매, 위험요인해소의 구조적 위험의 노령화 순으로 가장 중요한 것으로 나타났다. 중요도의 순위에 있어서 직접과 간접종사자간 의미 있는 차이를 확인할 수 있었다. 공무원, 수협중앙회 직원, 관련 교수 등으로 구성된 간접종사자의 종합평가 결과를 보면, 경쟁력강화의 생산공급의 원료구매, 생산시설, 고품질화순으로 나타났으나, 생산과 유통에 직접적으로 직접종사자의 경우는 위험요인해소의 환경적 위험의 해양오염, 구조적의 어가인구감소, 위험요인해소의 구조적의 노령화 순으로 나타나 종사자간 차이를 보였다. 종사자간 만족도에 있어서도 생산과 유통에 있는 직접종사자 보다 지원정책을 집행하는 간접종사자의 만족도가 통계적으로 유의한 차이를 보였다.