• Steel and Composite Structures
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• 제50권6호
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• pp.705-720
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• 2024

Analyzing the collapse behavior of thin-walled steel structures holds significant importance in ensuring their safety and longevity. Geometric imperfections present on the surface of metal materials can diminish both the durability and mechanical integrity of steel shells. These imperfections, encompassing local geometric irregularities and deformations such as holes, cavities, notches, and cracks localized in specific regions of the shell surface, play a pivotal role in the assessment. They can induce stress concentration within the structure, thereby influencing its susceptibility to buckling. The intricate relationship between the buckling behavior of these structures and such imperfections is multifaceted, contingent upon a variety of factors. The buckling analysis of thin-walled steel shell structures, similar to other steel structures, commonly involves the determination of crucial material properties, including elastic modulus, shear modulus, tensile strength, and fracture toughness. An established method involves the emulation of distributed geometric imperfections, utilizing real test specimen data as a basis. This approach allows for the accurate representation and assessment of the diversity and distribution of imperfections encountered in real-world scenarios. Utilizing defect data obtained from actual test samples enhances the model's realism and applicability. The sizes and configurations of these defects are employed as inputs in the modeling process, aiding in the prediction of structural behavior. It's worth noting that there is a dearth of experimental studies addressing the influence of geometric defects on the buckling behavior of cylindrical steel shells. In this particular study, samples featuring geometric imperfections were subjected to experimental buckling tests. These same samples were also modeled using Finite Element Analysis (FEM), with results corroborating the experimental findings. Furthermore, the initial geometrical imperfections were measured using digital image correlation (DIC) techniques. In this way, the response of the test specimens can be estimated accurately by applying the initial imperfections to FE models. After validation of the test results with FEA, a numerical parametric study was conducted to develop more generalized design recommendations for the stainless-steel shell structures with the initial geometric imperfection. While the load-carrying capacity of samples with perfect surfaces was up to 140 kN, the load-carrying capacity of samples with 4 mm defects was around 130 kN. Likewise, while the load carrying capacity of samples with 10 mm defects was around 125 kN, the load carrying capacity of samples with 14 mm defects was measured around 120 kN.

• 대한토목학회논문집
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• 제38권3호
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• pp.497-503
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• 2018

FIDIC 계약조건을 포함하여, 대부분의 국제건설계약조건에, 시공자들에게 부정적인 영향이나 재정적 부담을 필연적으로 야기시키는 유보금조항이 적용되고 있다. 본 연구를 통해 유보금 조항을 왜 적용하는지를 알아보고, FIDIC 계약조건에 포함된 이행보증과 하자관련 조항 및 계약해지 조항을 조사함으로써 유보금 적용에 대한 적정한 판단을 이끌어 내었다. 결론적으로 FIDIC 계약조건에 포함되어 있는 다수의 계약조건들과 이행보증 및 발주자에 의한 계약해지 조항 등의 내용을 고려할 때, 유보금 조항을 계약에 포함하는 것이 불필요하다.

• 상하수도학회지
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• 제31권6호
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• pp.619-628
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• 2017

As the 3D laser scanning technology capable of databaseing large sewage box culverts becomes possible, it is necessary to develop a standardization manual that can clearly distinguish the structural and operational defect types of box culver and analyze the defect data. In this study, we collected and analyzed defects in sewage box culverts of 14,827m in total by selecting three districts in Korea. The major defects were surface damages, and their defect densities were $2.17m^2/m$, $0.27m^2/m$ and $0.10m^2/m$ for aggregate exposure, Steel reinforcement exposure, and Steel reinforcement projecting. In order to support the decision of the box culverment management, it was divided into five grades and each defect code and defect score were allocated. The results of this study are useful for the diagnosis of the sewage box culverts in Korea and it is expected to support a decision making for management.

• 전기학회논문지
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• 제60권1호
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• pp.85-92
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• 2011

Main characteristic in railroad is the guided movement of the wheel by the track through a metal-to-metal contact, conferring to the rail vehicle a single degree of freedom. There are defects such as head check, shelling, corrugation, squats etc in surface of the rail by interface between the wheel and rail. These defects bring about reducing the life-cycle of rails and track components and increasing noises. In case of bad conditions, it is possible to happen to full-scale accident such as derailment. Recently, the track capacity has been increased for increasing speed and operation efficiency. So, maintenance and indirect cost have been increased. Currently, a coating method of rail construction is proposed by using the ceramics in Korea. Rails are used as the earth in electrical railroad systems. Currently traction return current is flowed through wheels of trains. In case of rails coated, problems are caused in the contact power between wheel and coating material of spray. In this paper, electric model is presented in the AT feeding method. In case of rails coated, electric model is presented. Also, standard resistance of the ceramic is demonstrated by contact power between wheel and coating material of spray.

• 융합정보논문지
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• 제11권9호
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• pp.138-144
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• 2021

전자부품 조립사업은 제품불량이 발생했을 때, 입고된 원자재불량 또는 작업불량을 추적하는 것이 중요하며, 결과에 따라 납품업체 또는 작업현장 개선이 중요하다. 스마트팩토리의 핵심 과제는 데이터 통합허브를 구축하여 저장·관리·분석을 실시간으로 처리하고 클러스터공정, 에너지, 환경, 안전을 통합관리 하는 것이다. 전자부품 관련 중소기업에 생산현장관리를 실시간 모니터링하여 생산데이터의 정확한 분석과 수집으로 신뢰도를 향상시키기 위해서는 스마트팩토리 구축이 필수적이다. 본 논문은 스마트팩토리를 도입하고자 하는 전자 부품관련 중소기업의 특성을 고려해 시스템 구성방법, 스마트팩토리 관련기술 과 적용사례 등을 정의하여 구축에 활용토록 개발되었다.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 추계학술논문발표회 논문집
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• pp.465-470
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• 2008

This paper introduces experimental investigates of an electrical accident of the distributing cable termination with simulated badness construction. We prepared two termination kites, one is built-up type, the other is heat contraction type. Also, we manufactured cable termination that have simulated defect by badness construction and measured their insulation characteristics such as ac (35kV, 1min) and impulse (95kV, $1.2{\times}50{\mu}s$) withstand test. The influence of defects such as thickness and the gap between stress-con of housing and semi-conductor on insulating properties of the termination have been studied. The thickness decrease of insulator decreases ac breakdown strength. Dielectric breakdown traces of insulator that is damaged by knife displayed other shape. The gap of between housing and semiconductor deteriorates dielectric strength of insulator seriously.

• 대한공간정보학회지
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• 제9권1호
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• pp.27-38
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• 2001

1995년 국가GIS사업이 추진된 이래 수치지형도를 활용한 GIS 구축사업이 활발하게 진행되고 있으나, 수치지형도의 기하학적 결점 및 위상관계가 정립되어 있지 않아서 GIS 구축 시 바로 활용할 수 없는 실정이다. GIS 선진국에서는 속성 자료와 공간 자료간의 위상이 정립된 자료를 GIS 사용자들에게 제공해주고 있는데, 이 자료를 프레임워크 자료(Framework Data) 즉, 기본지리정보라 하며 공간정보의 가장 핵심적이고 기본이 되는 자료로 활용하고 있다. 본 연구에서는 국가 공간정보의 기본도가 되는 국가기본지리정보의 범위와 정의를 설정하였으며, 기본지리정보 중 도시기반정보구축에 있어 가장 핵심이 되고 기준이 되는 교통/도로 기본지리정보 구축과 품질관리 방안에 관한 연구를 수행하였다.

• 대한조선학회 특별논문집
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• 대한조선학회 2008년도 특별논문집
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• pp.126-132
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• 2008

Cutting procedures whose qualifies are determined by various variables largely influences shipbuilding productivity. Particularly, defects in cutting shapes and cutting surface results in delay of the post shipbuilding stages such as welding and assemblage process. Because cutting procedures are influenced by various numbers of requirements according to the plate thickness, cutting precision can be maintained when the cutting conditions are appropriate. Existing cutting procedures utilize fossil fuels such as propane or ethylene as the main fuel component. Especially, when fossil fuel is applied to thick plate cutting, this process gives relatively slow cutting speed and generates large quantities of harmful polluting fumes. Recently, hydrogen-oxygen mixed gas generated by electrically dissociating water into Hydrogen and oxygen components is welcomed as an alternative fuel source. Also recent results report that alternative cutting fuel improves the cutting Dualities and speed. This paper presents that cutting characteristics and optimum cutting condition of hydrogen-oxygen mixed gas.

• Structural Monitoring and Maintenance
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• 제8권4호
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• pp.361-378
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• 2021

While the pavement rating system is being utilized for periodic road condition assessment in the Eastern Region municipality of Saudi Arabia, the condition assessment is costly, time-consuming, and not comprehensive as only few parts of the road are randomly selected for the assessment. Thus, this study is aimed at developing a condition assessment model for a specific sample of a residential road network in Dammam City based on an individual road and a road network. The model was developed using the Analytical Hierarchy Process (AHP) according to the defect types and their levels of severity. The defects were arranged according to four categories: structure, construction, environmental, and miscellaneous, which was adopted from sewer condition coding systems. The developed model was validated by municipality experts and was adjudged to be acceptable and more economical compared to results from the Eastern region municipality (Saudi Arabia) model. The outcome of this paper can assist with the allocation of the government's budget for maintenance and capital programs across all Saudi municipalities through maintaining road infrastructure assets at the required level of services.

• 한국건설관리학회논문집
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• 제21권4호
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• pp.12-20
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• 2020

도로 하부에 매설된 지하매설물에 대한 유지보수의 수요는 지속적으로 크게 증가하고 있으며, 과다한 소음 및 분진으로 인한 환경 문제 및 도심지 주민들의 민원으로 인해 친환경·저소음 도로 절단기에 대한 수요가 점차 증대되고 있다. 이에 따라 현재 사용되고 있는 저소음 절단기와 현재 개발되고 있는 친환경·저소음 절단기에 대한 절단 성능을 분석하고 개선사항을 검토해보자고 한다. 이를 위해 현장시공 사례를 바탕으로 절단기 작업절차에 따른 문제점과 개선 사항들을 도출하였다. 현장시공 사례 분석 결과, 절단 작업에 대한 생산성은 친환경·저소음 절단기(36.0초/m)가 저소음 절단기(37.6초/m)에 비해 다소 생산성이 향상되었으나 일부 구간에 결함이 발생되어 이에 대한 개선이 요구되었다.