• Smart Structures and Systems
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• v.32 no.3
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• pp.153-166
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• 2023

Health monitoring of civil infrastructures, in particular, old bridges that are still in service, has become more than necessary, given the risk that a possible degradation or failure of these infrastructures can induce on the safety of users in addition to the resulting commercial and economic impact. Bridge integrity assessment has attracted significant research efforts over the past forty years with the aim of developing new damage identification methods applicable to real structures. The bridge of Ouled Mimoun (Tlemcen, Algeria) is one of the oldest railway structure in the country. It was built in 1889. This bridge, which is too low with respect to the level of the road, has suffered multiple shocks from various machines that caused considerable damage to its central part. The present work aims to analyze the stability of this bridge by identifying damages and evaluating the damage rate in different parts of the structure on the basis of a finite element model. The applied method is based on an inverse analysis of the normal stress responses that were calculated from the corresponding recorded strains, during the passage of a real train, by means of a set of strain gauges placed on certain elements of the bridge. The results obtained from the inverse analysis made it possible to successfully locate areas that were really damaged and to estimate the damage rate. These results were also used to detect an excessive rigidity in certain elements due to the presence of plates, which were neglected in the numerical reference model. In the case of the continuous bridge monitoring, this developed method will be a very powerful tool as a smart health monitoring system, allowing engineers to take in time decisions in the event of bridge damage.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.625-637
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• 2015

This study aims to calculate optimal travel speeds based on analysis of the AVI data collected in the uninterrupted traffic flow, and the results are as follows. Firstly, we looked into the distribution of the sectional travel times of each probe vehicle and compared the difference in the sectional travel speeds of each probe vehicle. As a result, it is shown that outliers should be removed for the distribution of the sectional travel times. Secondly, there were differences among type 1(passenger automobiles) & type 2(automobiles for passengers and freight) and type 4(special automobiles) in the non-congestion section. thus it was revealed that there is a necessity to remove type 4(special automobiles) when calculating the sectional travel speeds. Thirdly, Based on the results of these, the optimal outlier removal procedures were applied to this study. As a result, it showed that the MAPE was between 0.3% and 2.0% and RMSE was between 0.3 and 2.3 which are very similar figures to the actual average traffic speed. Also, the minimum sample size was satisfied at the confidence level of 95%. The result of study is expected to serve as a useful basis for the local government to build the AVI. In the future, it will be necessary to study to integrate AVI data and other data for more accurate traffic information.

• Journal of Navigation and Port Research
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• v.45 no.6
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• pp.306-313
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• 2021

National fishing harbour is as a refuge for fishing boats and a breakwater lighthouse is installed as a functional facility in consideration of harbour identification and the safety of passing vessels. In this study, the service level of breakwater lighthouse (234 units) was estimated based on the traffic volume of 105 national fishing harbour. For this purpose, the evaluation items were determined, the fishing harbour standard index was calculated (Fs=1), the proximity of fishing harbour was identified and the function (service level) of the breakwater lighthouse was estimated in the following order. However, national fishing harbour differed in size, traffic volume and fishing vessel capacity. Therefore, 105 national fishing harbour were divided into three groups through cluster analysis. The cluster analysis was based on the service level factors of the breakwater lighthouse, such as the number of weeding fishing vessels, tonnage of fishing vessels, the number of incoming and outgoing vessels per year, and fishing vessel capacity. As a result of the estimation, the service level of the breakwater lighthouse (light tower height, visual height, visual range, interval) was 10.50m, 16.50m, 7.00mile, 5.5sec for group 1, and 10.67m, 16.16m, 8.33mile, and 6.0sec for group 2, The three groups are 11.53m, 16.75m, 6.75mile and 5.0sec. The results of this study can be used as useful basic data for improving the service level of traffic vessels when a breakwater lighthouse is built in a fishing harbour in the future.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.2
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• pp.130-135
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• 2014

For the past three decades, ship-to-ship collision accidents have steadily increased on the coast of South Korea by about 20% annually. Marine accidents have become more likely and more devastating in areas with increasing marine traffic and rising numbers of high-speed ships. Over 30% of the marine accidents in South Korea are concentrated in spring, since Korea's coast is often covered in dense fog at this time of the year. Fog is generated when a large temperature range exists within a day, and this daily temperature range has increased due to abnormal weather conditions. This research proposed a system for transmitting a navigator's intention utilizing electronic methods. A navigator's intention was expressed on the electronic navigation chart for easier understanding of the surrounding situation, and the effectiveness of the system was verified through practical tests.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.297-303
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• 2000

Damage estimation of a bridge structure is presented using ambient vibration data caused by the traffic loadings. The procedure consists of identification of the modal properties and assessment of the damage locations and severities. An experimental study is carried out on the bridge model subjected to vehicle loadings. Vertical accelerations of the bridge deck are measured at a limited number of locations. The modal parameters are identified from the free vibration signals extracted using the random decrement method. Then, the damage assessment is carried out based on the estimated modal parameters using the neural networks technique. The identified damage locations and severities agree reasonably well with the inflicted damages on the structure.

• Journal of Korean Institute of Industrial Engineers
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• v.35 no.1
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• pp.119-128
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• 2009

In this paper, we analyze the effect of the data aggregation level on the MAC performance when RFID (Radio Frequency Identification) logistics data, which can be aggregated at RFID readers to reduce the transmission overhead, are transmitted in IEEE 802.11 wireless LANs. For various data aggregation levels, the throughputs and latencies of the DCF (Distributed Coordination Function) and PCF (Point Coordination Function) MAC protocols are analyzed by computer simulation. From the simulation analysis, we propose the appropriate input traffic load for real-time RFID logistics data transmitted in IEEE 802.11 wireless LANs.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.7 no.3
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• pp.137-141
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• 2014

RFID system is applied to various industry such as process control, distribution management, access control, environment sensing, entity identification, etc. Since RFID system uses wireless communication, it has more weak points for security. In this paper, an authentication protocol is suggested between tags and a reader, which is basic property for security. A suggested protocol use a bivariate polynomial over a finite field and is secure against snooping, replay attack, position tracking and traffic analysis.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.427-430
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• 2002

The present parer outlines the system identification and vibration control performance of air traffic control tower of Yangyang international airport with tuned mass damper(TMD). From the free vibration test, natural frequency, damping ratio and mode shape of tower are obtained and these values are compared with the values from numerical analysis. In the vibration control test to evaluate the vibration control performance, equivalent damping ratio increased by tuned mass damper are obtained in case the TMD is operated as passive mode. Damping ratio of tower evaluated from free vibration test is about $1.0{\%}$. It is very low value than damping ratio recommended in general code. Damping ratio of passive mode is about $5{\%}$. These equivalent damping ratio increased by TMD is enough to enhance the serviceability of tower structure under wind load.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.41-42
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• 2019

해양공간의 효율적인 활용과 해상사고 예방을 위하여 해상교통 현황 파악이 필요하다. 이를 위해서는 해상에서 운항하는 선박에 대한 면밀한 모니터링이 선행 되어야한다. 때문에 본 연구에서는 선박자동식별장치(Automatic Identification System, AIS)와 선박패스(V-Pass)를 활용하는 기존 모니터링 방법에서 나아가, 위성 자료를 활용한 연안 선박감시 방법을 해상교통관제(Vessel Traffic Service, VTS) 센터에서 활용하기 위한 방안을 제안한다. 위성 자료는 광범위한 영역에 대하여 다양한 정보를 획득할 수 있는 장점을 지니므로, 부산항 연안에서 수집한 AIS 데이터와 함께 딥 러닝 기반 선박 탐지 및 분류 모델에 활용함으로써, 보다 개선된 모니터링을 기대할 수 있다. 이를 활용하여 미식별 선박들의 출현 위치를 분석하고 나아가 선박의 종류를 예측함으로써, 상세한 해상교통 현황 파악 및 예측을 기대할 수 있다. 향후에는 선박의 종류 뿐 아니라 각 선박의 해상활동을 분석함으로써, 보다 체계적이고 실용적인 해양공간활용 계획수립에 도움이 될 수 있도록 개선할 계획이다.

• Asia-Pacific Journal of Business
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• v.2 no.2
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• pp.36-60
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• 2011

Radio frequency identification(RFID) is a system of technology that transmits digitally coded identity information in the form of a unique serial number of an object or person wirelessly, using radio waves. The primary use of RFID has been in asset tracking. This makes it highly useful across various industries for effective and efficient conduct of different business processes like supply chain management (SCM). As the use of RFID expands, the use of this technology is observed in such industries as transportation, traffic payment, hospital and medical care, education, and retail. Although this technology offers immense potential, it faces multifarious roadblocks, particularly in developing countries like India. Under this backdrop, this paper attempts to present an overview of the use and application RFID technology in India with a highlight on business-ecosystem for RFID in India. We also present various technical and non-technical challenges in the implementation of RFID in India.