• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.1
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• pp.79-85
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• 2011

Bridge Weigh-in-Motion(BWIM) system calculates a travelling vehicle's weight without interruption of traffic flow by analyzing the signals that are acquired from various sensors installed in the bridge. BWIM system or data accumulated from the BWIM system can be utilized to development of updated live load model for highway bridge design, fatigue load model for estimation of remaining life of bridges, etc. Field test with moving trucks including various load cases should be performed to guarantee successful development of precise BWIM system. In this paper, a numerical simulation technique is adopted as an alternative or supplement to the vehicle traveling test that is indispensible but expensive in time and budget. The constructed numerical model is validated by comparison experimentally measured signal with numerically generated signal. Also vehicles with various dynamic characteristics and travelling conditions are considered in numerical simulation to investigate the variation of bridge responses. Considered parameters in the numerical study are vehicle velocity, natural frequency of the vehicle, height of entry bump, and lateral position of the vehicle. By analyzing the results, it is revealed that the lateral position and natural frequency of the vehicle should be considered to increase precision of developing BWIM system. Since generation of vehicle travelling signal by the numerical simulation technique costs much less than field test, a large number of test parameters can effectively be considered to validate the developed BWIM algorithm. Also, when artificial neural network technique is applied, voluminous data set required for training and testing of the neural network can be prepared by numerical generation. Consequently, proposed numerical simulation technique may contribute to improve precision and performance of BWIM systems.

• Smart Structures and Systems
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• v.29 no.1
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• pp.237-250
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• 2022

Structural health monitoring (SHM) plays an important role in ensuring the safety and functionality of critical civil infrastructure. In recent years, numerous researchers have conducted studies to develop computer vision and machine learning techniques for SHM purposes, offering the potential to reduce the laborious nature and improve the effectiveness of field inspections. However, high-quality vision data from various types of damaged structures is relatively difficult to obtain, because of the rare occurrence of damaged structures. The lack of data is particularly acute for fatigue crack in steel bridge girder. As a result, the lack of data for training purposes is one of the main issues that hinders wider application of these powerful techniques for SHM. To address this problem, the use of synthetic data is proposed in this article to augment real-world datasets used for training neural networks that can identify fatigue cracks in steel structures. First, random textures representing the surface of steel structures with fatigue cracks are created and mapped onto a 3D graphics model. Subsequently, this model is used to generate synthetic images for various lighting conditions and camera angles. A fully convolutional network is then trained for two cases: (1) using only real-word data, and (2) using both synthetic and real-word data. By employing synthetic data augmentation in the training process, the crack identification performance of the neural network for the test dataset is seen to improve from 35% to 40% and 49% to 62% for intersection over union (IoU) and precision, respectively, demonstrating the efficacy of the proposed approach.

• The Journal of Bigdata
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• v.7 no.1
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• pp.37-47
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• 2022

Autonomous delivery operation data is the key to driving a paradigm shift for last-mile delivery in the Corona era. To bridge the technological gap between domestic autonomous delivery robots and overseas technology-leading countries, large-scale data collection and verification that can be used for artificial intelligence training is required as the top priority. Therefore, overseas technology-leading countries are contributing to verification and technological development by opening AI training data in public data that anyone can use. In this paper, 326 objects were collected to trainn autonomous delivery robots, and artificial intelligence models such as Mask r-CNN and Yolo v3 were trained and verified. In addition, the two models were compared based on comparison and the elements required for future autonomous delivery robot research were considered.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.2
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• pp.141-148
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• 1997

This paper is concerned with the vibration control of multi-layer structure for ultra-tall buildings and main tower of large bridge etc. We have modeled the multi-layer structure with the distributed mass system as the lumped mass system of two-degree-of-freedom structure and made experimental equipment. The LQ optimal control theory is applied to the design of the control system. The designed control system is simulated by computer. As a result, the LQ regulator showed good vibration control performance with impact excitation.

• Steel and Composite Structures
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• v.9 no.5
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• pp.445-455
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• 2009

This study proposes a system identification technique for a fiber-reinforced polymer deck with neural networks. Neural networks are trained for system identification and the identified structure gives training data in return. This process is repeated until the identified parameters converge. Hence, the proposed algorithm is called an iterative neural network scheme. The proposed algorithm also relies on recent developments in the experimental design of the response surface method. The proposed strategy is verified with known systems and applied to a fiber-reinforced polymer bridge deck with experimental data.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2017.05a
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• pp.195-218
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• 2017

The paper tests the above socio-cognitive model with four empirical case studies of leading Korean science and technology research and technology transfer organizations. The case studies demonstrate clear differences in individuals' frames about the technology transfer process and arising conflicts. As a result, technology transfer process is not fully controllable and is highly contextual. We argue, whereas public policy in countries approaching technology frontier provides essential support for defining and exploiting best practices (routines/pathways) for technology transfer at organizational level, they have not matured enough to support the timely identification and resolution of conflicts between individual actors, hence the inefficiencies. Therefore, among others, public policy for technology transfer could consider allowing an inclusive approach to recognition of best practices for technology transfer and innovation processes, increased social interactions between technology transfer actors, and their training on resolution of individual level cognitive conflicts.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.06a
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• pp.93-105
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• 2000

This paper describes prototype Virtual Reality Ship Simulator (VRSS) that we have recently developed next-generation training equipment based on the virtual reality (VR) technology. The inherent defects of conventional ship simulators are enormous costs and difficult system upgrade due to the system construction, such as large mock-up bridge system, wide visual presentations, In this paper, to cope with those problems, we explored VR technology that can give realistic environments in a virtual world. Then we constructed prototype VRSS system, which is, consists of PC-based human sensors, and Databases set having 3D object models and coefficients of Head Related Transfer Functions (HRTFs). 3D-WEBMASTER authoring tool was used as Virtual Reality Modeling Language (VRML). Using the VRSS system, we constructed Port an Passage Simulator for the harbor of INCHON in Korea, and Ship and Sea State Simulator for an arbitrary given sea environmental states by user. Through many simulation tests, we testified the efficiency of developed prototype VRSS by subject assessment with five participants. Then, we present results on the simulation experiments and conclude with discussion of evaluation results.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.10a
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• pp.85-95
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• 1998

ECDIS, highlihgted as a new technology for the navigation safety, could replace the paper charts in the bridge and make the more safe navigation possible. For the marines to use the ECDIS, the infrastructrue of the ENC production and distribution, the development of IMO compliant ECDIS, the training program for the ECDIS usage and related matters are thought as the key points to be solved. Also it is necessary for the ECDIS usage and related maters are thought as the key point to be solved. Also it is necessary for the related groups, such as ECDIS manufactures, users, ENC producers, the to be involved in developing the national infrastructure altogether to promote the ECDIS usage. Upon these background, the Korean ENC pilot project was introduced and the comparison study of the SHARED project coordinated by MPA(Maritime Port Authority, Singapore) and the Canadan Pilot project has been done. With such a analysis, the Korean ENC sea trial test plan is presented.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.08a
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• pp.177-185
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• 2004

This paper describes Listening Decision Aid Simulator (LDAS) to provide a decision-supporting tool that can reproduce real-like listening situations focused on the duty officer's two ears. The sound propagation mechanism from a whistle to listener's two ears is established at first, and the spatial transfer coefficients of a bridge door are measured at training vessel. Then, the construction works with the spatial transfer coefficients and its evaluation experiments with five collision accidents are carried out. As results from tests, the five cases can be judge by LDAS; it led to the insight of practical use of LDAS as one of the decision supporting system in collision accidents.

• Proceedings of KOSOMES biannual meeting
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• 2002.10a
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• pp.111-124
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• 2002

Ship manoeuvring simulator has been widely utilized for training mariners, for assessing safety, for developing harbour and port, and for designing ships. We discuss a ship manoeuvring simulator which has been newly developed by Korea Maritime University. The simulator consists of simulator bridge and control console. All the computers used in the simulator are connected with one another by UDP or TCP network system. All the instruments are connected with interface computer by signal line which is controlled by RS232 communication protocol, or by voltage controlled A/D board. Next the mathematical model of ship manoeuvring motion in harbour areas, and ship and terrain modeling technique are also briefly discussed. Finally using the simulator an experiment of distance cognition and a simulation example of berthing/deberthing manoeuvre are shown.