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Restoration of pre-damaged RC bridge columns using basalt FRP composites

  • Fahmy, Mohamed F.M.;Wu, Zhishen
    • Earthquakes and Structures
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    • 제14권5호
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    • pp.379-388
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    • 2018
  • This study aims to identify the effect of both longitudinal reinforcement details and damage level on making a decision of repairing pre-damaged bridge columns using basalt fiber reinforced polymer (BFRP) jackets. Two RC bridge columns with improper details of the longitudinal and/or transverse reinforcement were tested under the effect of a constant axial load and increasing lateral cyclic loading. Test results showed that the lap-splice column exhibited an inferior performance where it showed rapid degradation of strength before achieving the theoretical strength and its deformation capacity was limited; however, quick restoration is possible through a suitable rehabilitation technique. On the other hand, expensive repair or even complete replacement could be the decision for the column with the confinement failure mode. After that, a rehabilitation technique using external BFRP jacket was adopted. Performance-based design details guaranteeing the enhancement in the inelastic performance of both damaged columns were addressed and defined. Test results of the repaired columns confirmed that both reparability and the required repairing time of damage structures are dependent on the reinforcement details at the plastic hinge zone. Furthermore, lap-splice of longitudinal reinforcement could be applied as a key design-tool controlling reparability and restorability of RC structures after massive actions.

노치변형률법을 적용한 용접구조상세의 피로수명평가 (Fatigue Life Estimation of Welding Details by Using a Notch Strain Approach)

  • 한정우;한승호;신병천;김재훈
    • 대한기계학회논문집A
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    • 제28권7호
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    • pp.977-985
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    • 2004
  • An evaluation of fatigue life of welded components is complicated due to various geometrically complex welding details and stress raisers in vicinity of weld beads, ego under cuts, overlaps and blow holes. These factors have a considerable influence on the fatigue strength of welded joints, as well as the welding residual stress which is relaxed depending on the distribution of local stress at the front of the stress raisers. To reasonably evaluate fatigue life, the effect of geometries and welding residual stress should be taken into account. The several methods based on the notch strain approach have been proposed in order to accomplish this. These methods, however, result in differences between analytical and experimental results due to discrepancies in estimated amount of relaxed welding residual stress present. In this paper, an approach that involves the use of a modified notch strain approach considering geometrical effects and a residual stress relaxation model based on experimental results was proposed. The fatigue life for five types of representative welding details, ego cruciform, cover plate, longitudinal stiffener, gusset and side attachment joint, are evaluated using this method.

중년여성의 수트 착용 형태미를 위한 형태 구성요인의 조합에 관한 연구 (A Study on the Combination of Suit Details for Image of Classic Style Suits-Middle Aged Women′s Body Construct)

  • 위은하;김옥진
    • 복식문화연구
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    • 제8권5호
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    • pp.726-740
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    • 2000
  • The purpose of this study is to evaluate the combination of suit details through visual evaluation which helps compensating the classic style suits-middle aged women's body construct for their more attractive fashion styles. The styles of the evaluated suits are formal and classical. The designs of evaluated suits are manipulated in 40 different kinds by the essential elements such as collars, necklines(tailored collars, soutien collars, stand collars, round necklines, V-necklines, etc.), bottoms(slacks, skirts), pocket (flap pocket, none) and opening(opened, closed). The data evaluated by a multiple ranking test were analyzed by paired t-test, ANOVA and Duncan's multiple raged test. The results are summarized as follows : 1. A middle aged woman on skirts suits look more graceful, more elegant, and a bit more refined than that on slacks suits. 2. A middle aged woman wearing a jacket with flap pockets on looks more balanced, and graceful than when wearing with no pockets. 3. Wearing closed jackets looks more balanced and graceful than on opened jackets. 4. The types of collar·necklines can be called the details which put much influence on Image effects. Putting on tailored collar suits is the most graceful, refined, balanced and harmonious case than any others.

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Geoscience 연구데이터 관리를 위한 기능별 세부요소 및 중요도에 관한 연구 (A Study on Functional Details and Importance of Geoscience Research Data Management)

  • 김주섭;김선태;최상기
    • 한국문헌정보학회지
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    • 제54권1호
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    • pp.411-440
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    • 2020
  • 본 연구는 국내에서 Geoscience 분야 연구데이터 관리 시스템 개발에 적용할 수 있는 RDM 기능별 세부요소의 도출을 목적으로 하였다. 연구 목적 달성을 위해 RDM 서비스와 관련된 8개의 기관을 분석하였다. 분석한 결과, Geoscience RDM 기능의 80개 세부요소가 도출되었으며, 도출된 세부요소를 검증하기 위하여 국내 전문가를 대상으로 설문조사를 수행하였다. 조사 결과, Geoscience 분야를 위한 80개의 RDM 기능별 세부요소가 중요도 순으로 제시되었다. 제시된 요소는 국내의 연구 기관 또는 대학도서관에서 Geoscience 분야의 RDM 서비스 구축 및 운영 시 기능별 세부요소로 제시될 수 있으며 순위에 따라 중요도를 판단할 수 있는 참고자료가 될 수 있을 것이다.

A Noisy Infrared and Visible Light Image Fusion Algorithm

  • Shen, Yu;Xiang, Keyun;Chen, Xiaopeng;Liu, Cheng
    • Journal of Information Processing Systems
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    • 제17권5호
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    • pp.1004-1019
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    • 2021
  • To solve the problems of the low image contrast, fuzzy edge details and edge details missing in noisy image fusion, this study proposes a noisy infrared and visible light image fusion algorithm based on non-subsample contourlet transform (NSCT) and an improved bilateral filter, which uses NSCT to decompose an image into a low-frequency component and high-frequency component. High-frequency noise and edge information are mainly distributed in the high-frequency component, and the improved bilateral filtering method is used to process the high-frequency component of two images, filtering the noise of the images and calculating the image detail of the infrared image's high-frequency component. It can extract the edge details of the infrared image and visible image as much as possible by superimposing the high-frequency component of infrared image and visible image. At the same time, edge information is enhanced and the visual effect is clearer. For the fusion rule of low-frequency coefficient, the local area standard variance coefficient method is adopted. At last, we decompose the high- and low-frequency coefficient to obtain the fusion image according to the inverse transformation of NSCT. The fusion results show that the edge, contour, texture and other details are maintained and enhanced while the noise is filtered, and the fusion image with a clear edge is obtained. The algorithm could better filter noise and obtain clear fused images in noisy infrared and visible light image fusion.

Reflectance estimation for infrared and visible image fusion

  • Gu, Yan;Yang, Feng;Zhao, Weijun;Guo, Yiliang;Min, Chaobo
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제15권8호
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    • pp.2749-2763
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    • 2021
  • The desirable result of infrared (IR) and visible (VIS) image fusion should have textural details from VIS images and salient targets from IR images. However, detail information in the dark regions of VIS image has low contrast and blurry edges, resulting in performance degradation in image fusion. To resolve the troubles of fuzzy details in dark regions of VIS image fusion, we have proposed a method of reflectance estimation for IR and VIS image fusion. In order to maintain and enhance details in these dark regions, dark region approximation (DRA) is proposed to optimize the Retinex model. With the improved Retinex model based on DRA, quasi-Newton method is adopted to estimate the reflectance of a VIS image. The final fusion outcome is obtained by fusing the DRA-based reflectance of VIS image with IR image. Our method could simultaneously retain the low visibility details in VIS images and the high contrast targets in IR images. Experiment statistic shows that compared to some advanced approaches, the proposed method has superiority on detail preservation and visual quality.

전단파괴모드를 고려한 철근콘크리트 보통전단벽-골조 건물의 붕괴메커니즘 (Collapse Mechanism of Ordinary RC Shear Wall-Frame Buildings Considering Shear Failure Mode)

  • 추유림;김태완
    • 한국지진공학회논문집
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    • 제25권1호
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    • pp.1-9
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    • 2021
  • Most commercial buildings among existing RC buildings in Korea have a multi-story wall-frame structure where RC shear wall is commonly used as its core at stairways or elevators. The members of the existing middle and low-rise wall-frame buildings are likely arranged in ordinary details considering building occupancy, and the importance and difficulty of member design. This is because there are few limitations, considerations, and financial burdens on the code for designing members with ordinary details. Compared with the intermediate or unique details, the ductility and overstrength are insufficient. Furthermore, the behavior of the member can be shear-dominated. Since shear failure in vertical members can cause a collapse of the entire structure, nonlinear characteristics such as shear strength and stiffness deterioration should be adequately reflected in the analysis model. With this background, an 8-story RC wall-frame building was designed as a building frame system with ordinary shear walls, and the effect of reflecting the shear failure mode of columns and walls on the collapse mechanism was investigated. As a result, the shear failure mode effect on the collapse mechanism was evident in walls, not columns. Consequently, it is recommended that the shear behavior characteristics of walls are explicitly considered in the analysis of wall-frame buildings with ordinary details.

국내 PC 아파트 접합부 누수 방지를 위한 마감상세 분석 (Analysis of finishing details to Prevent leakage of PC Apartment Joints in Korea)

  • 김태호;고효진
    • 한국공간구조학회논문집
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    • 제21권4호
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    • pp.81-89
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    • 2021
  • Recently, interest in OSC(Off Site Construction) is increasing due to the trend of a decrease in skilled workers and an increase in labor costs. In this regard, PC(Precast Concrete) is being reviewed for apartments, the most common type of housing in Korea. As the biggest concern for PC apartment houses, civil complaints such as inter-floor noise and leakage were presented. In this study, the details of the joints were reviewed based on the past cases of PC apartments, and the details of the recently constructed or planned PC apartments were investigated. Through this, the leakage path in the past was analyzed through the existing research literature and data. And wall type RC and PC apartment joint leakage test was performed and we found the needs for a detail of waterproof steps, sealant. Also, joint details were investigated for a rahmen type apartment housing under construction. At last, A discussion was conducted on the direction for a detailed proposal of an improved joint in the future.

기계부품의 세척성 평가에 관한 연구 (A Study on Cleaning-ability Evaluation for Mechanical Components)

  • 전창수
    • 한국산업융합학회 논문집
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    • 제25권6_3호
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    • pp.1315-1324
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    • 2022
  • The need for remanufacturing ships and various mechanical components continues to increase along with environmental problems. Research on remanufacturing is being carried out in various fields, but research on cleaning is quite insufficient. In particular, there is no research on the cleaning-ability of diverse mechanical components. In order to increase the life cycle of mechanical components, remanufacturing must be considered from the step of design. Particularly, it is also very important to evaluate the degree of easiness in cleaning to remove various pollutants generated by long-term use quickly as well as easily. In this study, the degree of easiness in cleaning is defined as cleaning-ability. In fact, remanufacturing components can be easily done only when cleaning-ability is set high from the step of design. The purpose of this study is to evaluate the cleaning-ability of ships and various mechanical components. The details of easiness in cleaning are cleaning and drying identification, accessibility to cleaning tools, convenience in cleaning, and convenience in drying. This study presents a quantitative procedure to evaluate cleaning-ability, derived various factors influencing each of the details of easiness and their ranges, and gave scores to the factors according to their ranges. The weight was also calculated for the details of easiness in cleaning and the factors. Lastly, this researcher suggests a scoring procedure to evaluate cleaning-ability quantitatively and the total weight of cleaning-ability.

유조선 종통보강재와 횡늑골 연결부의 피로강도 평가용 자동화 시스템 개발 (Development of Evaluation System for Fatigue Strength on the Connection Between Longitudinals and Transverse Web)

  • 홍기섭;김성찬;안재욱;김성기
    • 대한조선학회논문집
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    • 제46권5호
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    • pp.510-519
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    • 2009
  • Ship structure is composed of the welded mixture members which are plate and stiffeners. Ship structure is also influenced by variable loadings such as wave and inertia load. There have been several fatigue damage problems on the connection between longitudinal and transverse web due to wide usage of high tensile steel and adoption of wide web space to improve shipbuilding productivity. It is impossible to estimate the fatigue lives for all connection details through refined fatigue analysis. It is necessary to use the simplified approach for the fatigue life estimation of the connection details. PLUS analysis, which is suggested by the classification society, is one of the simplified approaches and is widely adopted to get fatigue lives for the connection details along whole cargo hold area. However, ship building yards still have difficulties to get fatigue lives due to large amount of calculation and time even if this approach reduce the time and amount of calculation. This paper treats the computing system developed to reduce efforts of estimating the fatigue lives. The influence factors of mean shear stress and local dynamic pressure are easily calculated and fatigue lives for all hot spots can be estimated automatically by the developed computing system. It is possible to reduce computing time and efforts to get the fatigue lives for the connection details between longitudinals and transverse webs along the ship. This system was applied to get fatigue lives on the connection details of a VLCC and verified the availability.