Evaluation method for time-dependent corrosion depth of uncoated weathering steel using thickness of corrosion product layer

Kainuma, Shigenobu,Yamamoto, Yuya,Ahn, Jin-Hee,Jeong, Young-Soo Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.2

The corrosion environments in a steel structure are significantly different depending on the individual parts of the members. To ensure the safety of weathering steel structures, it is important to evaluate the time-dependent corrosion behavior. Thus, the progress and effect of corrosion damage on weathering steel members should be evaluated; however, the predicted corrosion depth, which is affected by the corrosion environment, has not been sufficiently considered until now. In this study, the time-dependent thicknesses of the corrosion product layer were examined to quantifiably investigate and determine the corrosion depth of the corroded surface according to the exposure periods and corrosion environments. Thus, their atmospheric exposure tests were carried out for 4 years under different corrosion environments. The relationship between the thickness of the corrosion product layers and mean corrosion depth was examined based on the corrosion environment. Thus, the micro corrosion environments on the skyward and groundward surfaces of the specimens were monitored using atmospheric corrosion monitor sensors. In addition, the evaluated mean corrosion depth was calculated based on the thickness of the corrosion product layer in an atmospheric corrosion environment, and was verified through a comparison with the measured mean corrosion depth.

Stress distribution on the real corrosion surface of the orthotropic steel bridge deck

Shigenobu Kainuma,정영수,안진희 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.6

This study evaluated the localized stress condition of the real corroded deck surface of an orthotropic steel bridge because severe corrosion damage on the deck surface and fatigue cracking were reported. Thus, a three-dimensional finite element (FE) analysis model was created based on measurements of the corroded orthotropic steel deck surface to examine the stress level dependence on the corrosion condition. Based on the FE analysis results, it could be confirmed that a high stress concentration and irregular stress distribution can develop on the deck surface. The stress level was also increased by approximately 1.3-1.5times as a result of the irregular corroded surface. It was concluded that this stress concentration could increase the possibility of fatigue cracking in the deck surface because of the surface roughness of the orthotropic steel bridge deck.

Occlusion-Robust Segmentation for Multiple Objects using a Micro Air Vehicle

Asahi Kainuma,Hirokazu Madokoro,Kazuhito Sato,Nobuhiro Shimoi 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

This paper presents a novel object extraction method using a micro air vehicle (MAV) for improving the robustness of occlusion. The proposed method is based on saliency of objects for extracting regions of interest (RoIs) using scale invariant feature transform (SIFT) features and segmentation of target objects using GrabCut, which requires advance learning. We obtained original aerial photographic time-series image datasets using a MAV. Results of experiments revealed that object extraction accuracies measured using precision, recall, and F-measure improved according to the MAV movement for images with changing rates of collusion between two objects: a chair and a table. Especially for images of a chair, which is smaller than the table, our method functioned well for the extraction of object regions. For improving extraction accuracy based on the result to extract the table, an advanced mechanism combined with flight patterns is necessary to adjust the suitable distance between the MAV and a target object.

Fatigue Behavior Investigation and Stress Analysis for Rib-to-Deck Welded Joints in Orthotropic Steel Decks

Shigenobu Kainuma,Muye Yang,정영수,Susumu Inokuchi,Atsunori Kawabata,Daisuke Uchida 한국강구조학회 2018 International Journal of Steel Structures Vol.18 No.2

The fatigue problems in orthotropic steel decks have raised widely concerns in recent years. This study focused on the root crack mechanism at rib-to-deck welded joints, based on the previous test results of sectional specimens and the matching FE analysis, the fatigue behaviors of structure detail were investigated by considering the eff ect of root gap shapes, weld penetrations, and plate thicknesses on crack initiation. Besides, various root crack depths were simulated in models to clarify the stress variations occurring during the propagation stage under cyclic loading. The results showed that the root gap shape and penetration rate have an impact on the root cracking direction and fatigue life at the initiation stage, but seem not directly related to the crack propagation mechanism; the higher penetration rate is advantageous for the prevention of root crack initiation. However, although the stiff ness increased with the increase in plate thickness, the fatigue life of crack initiation might be reduced owing to the low fatigue strength of the thick deck plate, whereas the U-rib thickness has limited eff ect on the stress response of the root tip. Moreover, the signifi cant diff erence between the 8 mm-crack model and other crack models is the high stress concentration around the crack tip. The stress conditions of root tip would be changed under loading cycles when a root crack propagated into half of deck plate thickness. Finally, the eff ect of structural dimensions on fatigue strength were also compared according to test results and FEA.

Development of modeling and analysis techniques for information sharing on supply chain

Yasutaka Kainuma,Nobuhiko Tawara 한국경영정보학회 2000 한국경영정보학회 학술대회논문집 Vol.2000 No.-

Evaluation method for time-dependent corrosion depth of uncoated weathering steel using thickness of corrosion product layer

Shigenobu Kainuma,Yuya Yamamoto,안진희,정영수 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.2

The corrosion environments in a steel structure are significantly different depending on the individual parts of the members. To ensure the safety of weathering steel structures, it is important to evaluate the time-dependent corrosion behavior. Thus, the progress and effect of corrosion damage on weathering steel members should be evaluated; however, the predicted corrosion depth, which is affected by the corrosion environment, has not been sufficiently considered until now. In this study, the time-dependent thicknesses of the corrosion product layer were examined to quantifiably investigate and determine the corrosion depth of the corroded surface according to the exposure periods and corrosion environments. Thus, their atmospheric exposure tests were carried out for 4 years under different corrosion environments. The relationship between the thickness of the corrosion product layers and mean corrosion depth was examined based on the corrosion environment. Thus, the micro corrosion environments on the skyward and groundward surfaces of the specimens were monitored using atmospheric corrosion monitor sensors. In addition, the evaluated mean corrosion depth was calculated based on the thickness of the corrosion product layer in an atmospheric corrosion environment, and was verified through a comparison with the measured mean corrosion depth.

Time-Dependent Prediction on the Localized Corrosion of Steel Structure Using Spatial Statistical Simulation

Shigenobu Kainuma,Muye Yang,Jiajing Xie,Young-Soo Jeong 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.3

The structural failure induced by the localized corrosion of steel members frequently occurred. In this study, a spatial statistical technique was developed to predict the time-dependent localized corrosion initiated at the boundary zone of steel and concrete. 20 specimens were prepared by embedding steel plate into concrete block, the accelerated corrosion tests of 600, 1200, 1800, and 2400 cycles were conducted to obtain the actual surface fi guration with uniform and localized corrosion. After performing the regression tree analysis to divide the corrosion surface into localized and uniformed corrosion regions, a semi-variogram was used as the statistical technique to generate the corrosion prediction model, and an ordinary Kriging model to estimate the probable corrosion depth at arbitrary locations. The simulated results show that the probability distribution of corrosion depth and surface topography of both localized and uniform corrosion surfaces are highly consistent with the test. Also, the estimated surfaces owned a similar stress concentration eff ect to the actual surface, although their localized corrosion distributes diff erently. The prediction results of 2400–9600 cycles show that the top fi ve SCF values of simulation almost within the 95% confi dence interval of the fi tting curves of test results. Therefore, the accuracy of the estimated corrosion surface is considered reasonable using the spatial statistical simulation method.

Evaluation method of sustainable supply chain performance

Yasutaka KAINUMA 대한산업공학회 2018 대한산업공학회 추계학술대회논문집 Vol.2018 No.11

강도로교의 부식손상 현황과 과제

시재노부 카이누마,KAINUMA, Shigenobu 한국구조물진단유지관리공학회 2014 한국구조물진단유지관리공학회지 Vol.18 No.3

Decision Model Development under Different Scenarios for New Product Development

Thanyatorn Fongsatitkul,Yasutaka Kainuma 대한산업공학회 2020 Industrial Engineeering & Management Systems Vol.19 No.3

Under a highly competitive market, companies have to develop a new product as an effective strategy to maintain or even enhance their market shares. New product development (NPD) with an involvement of environmental dimension, nowadays, is one of the most crucial factors for business success. A feasibility study and a milestone of the NPD project have to be systematically established and subsequently evaluated. A Bayesian decision analysis was then employed to deal with three uncertainties of the future market shares with or without an environmental-friendly component and the competitors’ responses, producing expected values and variances for three uncertainties. An application of a decision model using MATLAB can be an effective tool to identify whether or not the NPD project under different scenarios should be continued in terms of future expected profits. Four scenarios were explored: Business as usual (BAU), improvements with or without an involvement of environmental aspects, and project termination. Moreover, three uncertainties were also considered: market status (future conventional market share and environmentallyfriendly market share), and competitors’ reactions. Sensitivity analysis of the selected scenario/model under three uncertainties was finally established to identify the effects of change in the uncertainties as the input parameters with respect to the output profit.