• Smart Structures and Systems
• /
• 제31권4호
• /
• pp.335-349
• /
• 2023

Bridges constantly undergo deterioration and damage, the most common ones being concrete damage and exposed rebar. Periodic inspection of bridges to identify damages can aid in their quick remediation. Likewise, identifying components can provide context for damage assessment and help gauge a bridge's state of interaction with its surroundings. Current inspection techniques rely on manual site visits, which can be time-consuming and costly. More recently, robotic inspection assisted by autonomous data analytics based on Computer Vision (CV) and Artificial Intelligence (AI) has been viewed as a suitable alternative to manual inspection because of its efficiency and accuracy. To aid research in this avenue, this study performs a comparative assessment of different architectures, loss functions, and ensembling strategies for the autonomous segmentation of bridge components and damages. The experiments lead to several interesting discoveries. Nested Reg-UNet architecture is found to outperform five other state-of-the-art architectures in both damage and component segmentation tasks. The architecture is built by combining a Nested UNet style dense configuration with a pretrained RegNet encoder. In terms of the mean Intersection over Union (mIoU) metric, the Nested Reg-UNet architecture provides an improvement of 2.86% on the damage segmentation task and 1.66% on the component segmentation task compared to the state-of-the-art UNet architecture. Furthermore, it is demonstrated that incorporating the Lovasz-Softmax loss function to counter class imbalance can boost performance by 3.44% in the component segmentation task over the most employed alternative, weighted Cross Entropy (wCE). Finally, weighted softmax ensembling is found to be quite effective when used synchronously with the Nested Reg-UNet architecture by providing mIoU improvement of 0.74% in the component segmentation task and 1.14% in the damage segmentation task over a single-architecture baseline. Overall, the best mIoU of 92.50% for the component segmentation task and 84.19% for the damage segmentation task validate the feasibility of these techniques for autonomous bridge component and damage segmentation using RGB images.

• 한국소음진동공학회논문집
• /
• 제23권2호
• /
• pp.152-159
• /
• 2013

A structural health monitoring(SHM) technique for locating impact position in a composite plate is presented in this paper. The technique employs a single sensor and spatial focusing properties of time reversal(TR) and inverse filtering(IF). We first examine the focusing effect of back-propagated signal at the impact position and its surroundings through simulation. Impact experiments are then carried out and the localization images are found using the TR and IF signal processing, respectively. Both techniques provide accurate impact location results. Compared to existing techniques for locating impact or acoustic emission source, the proposed methods have the benefits of using a single sensor and not requiring knowledge of material properties and geometry of structures. Furthermore, it does not depend on a particular mode of dispersive Lamb waves that is frequently used in the SHM of plate-like structures.

• Geomechanics and Engineering
• /
• 제13권4호
• /
• pp.685-699
• /
• 2017

In order to determine the rate of penetrability, water pressure test is used before the grouting. One of the parameters which have the highest effect is pressure. Mathematical modeling is used for the first time in this study to determine the optimum pressure. Thus, the joints that exist in the rock mass are simulated using cylindrical shell model. The joint surroundings are also modeled through Pasternak environment. In order to validate the modeling, pressure values obtained by the model were used in the sites of Seymareh and Aghbolagh dams and the relative error rates were measured considering the differences between calculated and actual pressures recorded in these operations. In water pressure test, in Seymareh dam, the error values were equal to 4.75, 3.93, 4.8 percent and in the Aghbolagh dam, were 22.43, 5.22, 2.6 percent and in grouting operation in Seymareh dam were equal to 9.09, 32.50, 21.98, 5.57, 29.61 percent and in the Aghbolagh dam were 2.96, 5.40, 4.32 percent. Due to differences in rheological properties of water and grout and based on the overall results, modeling in water pressure test is more accurate than grouting and this error in water pressure test is 7.28 percent and in grouting is 13.92 percent.

• 한국멀티미디어학회논문지
• /
• 제18권9호
• /
• pp.1047-1057
• /
• 2015

In this paper, we propose an effective wireless transmission technology, under poor wireless transmission channel surroundings caused by speedy flying, that are able to transmit high quality video recording information and surveillance data via accessing to various wireless networking services architecture such as One-on-One, Many-on-One, One-on-Many, Over the Horizon. The Real-Time Position Analysis(RAPA) method is also suggested to provide more meaningful video information of shooting area. The suggested wireless transmission technology and RAPA can make remote control of UAV's flight route to get valuable topography information. Because of the benefit to get both of video information and GPS data of shooting area simultaneously, the result of study can be applied to various application sphere including UAV that requires high speed wireless transmission.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2006년도 추계학술대회 논문집(제2권)
• /
• pp.13-17
• /
• 2006

Almost every day close passage or near miss events happens in south part of Istanbul Strait between the vessel runs in the local area and pass strait transit. The vessels run in the local area pass close bow or aft of transit vessel or come close and wait for transit vessel because of inexperienced or incompetent skipper or because of time limitation or failure in technical equipment or lack of technical equipment or old equipment. This close passages create profound dangers for the surroundings. By the this research has been aimed to point out mentioned dangers by the concrete as number. For this purpose has been utilized JMS Ship Handling Simulator which has been settled in ITU Maritime Faculty and Environmental Stress Model which has been built up and improved in Inoue Laboratory. Has been put in the senarios which been played during simulation implementations transferred to the numerical risk occured during passage of South Part of Istanbul Strait by the Environmental Stress Model . Thus so, the riskwhich Istanbul Strait face everyday has been expressed as numerical and concrete.

• Architectural research
• /
• 제16권4호
• /
• pp.185-192
• /
• 2014

As the cities developed and grew into larger metropolises, land value grew and land invariably became an asset. One of very critical causalities of such widespread need for development was the urban residence that got converted into cesspools of urban slum, major crime area and rapidly degraded. Incessant population growth of these cities called for more land to build residences especially the economically affordable and safe housings were needed for the citizens of none or low-income community. However, not enough attentions have yet been given to the essential basics of human habitation that exist within metropolitan limits by social, economical and political aspects. The following paper studies and elaborates the development motivation adopted by the government to develop public housing in the United States under the technical guidance of supporters and developers from national and international communities. The paper discusses current situation of public housing in the United States with a focus on understanding the present status of public housing and physical condition of their surroundings, strategies for fund mobilization, types of local involvement and community participation, ways of continuous monitoring and maintenance, etc. thereby creating a self-sustaining and integrated management plan for public housings in the future.

• 한국정밀공학회지
• /
• 제30권12호
• /
• pp.1265-1271
• /
• 2013

In this work, modeling and analysis of thermal effects laser drilling under water for ceramics were presented. Laser is a unique tool for machining ceramics due to the characteristic of non-contact material removal. However, ablation by a laser often induces a thermal effect on the material and an increased heat-affected-zone or deposition of debris can be observed on the machined parts. The underwater surrounding improved a heat transfer rate to cooling down the machined part and could prevent any deposition of debris near the machined surfaces and edges. The heat modeling was applied to obtain the temperature distributions as well as temperature gradients between the material and surroundings. The cooling effect of the underwater laser drilling was improved and a more stable temperature distribution was calculated. The actual laser drilling results of ceramic laser drilling were presented to verify the effects of underwater laser drilling.

• 한국의류산업학회지
• /
• 제11권2호
• /
• pp.219-230
• /
• 2009

The purpose of this paper is to study characters' make-up coordination that changes the narrative of the fantasy movies to a visual fantasy, especially it focuses on the post-modern features from the works of Tim Burton, a post-modernist. The contents of the study are, firstly, studying post-modernism that influenced the works of Tim Burton, secondly, researching (1988), (1989), (1990), (1992), (2003) and (2005) and their main characters' make-up design. Thirdly, analyzing the otherness and plural-code that are the post-modern characteristics expressed on characters' make-up coordination of fantasy movies. The otherness means the division of the middle and the surroundings and the rise of the outsiders. Fantasy characters that scares off human such as ghosts, aliens, apes, kidults, mutations, man-made men are in the middle. The plural-code takes the symbolic and pluralistic dimension in to the movie, mixes the sign system, and which natural and supernatural system cross over. In the movies, Beetle Juice who was both ghost and devil expresses life and death, Bat man, Cat woman, Penguin man expresses human and animal, and Edward means human and inhuman. Willy Wonka's makeup makes him look younger, but his grown-up-like clothes show doubleness. For that matter, make-up coordination is the mirror of reflection of period and human being's inner life.