• Smart Structures and Systems
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• 제12권3_4호
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• pp.415-426
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• 2013

Condition assessment and monitoring of bridges is critical for safe passenger travel, public transportation, and efficient freight. In monitoring, displacement measurement capability is important to keep track of performance of bridge, in part or as whole. One of the most important parts of a bridge is the expansion joint, which accommodates continuous cyclic thermal expansion of the whole bridge. Though expansion joint is critical for bridge performance, its inspection and monitoring has not been considered significantly because the monitoring requires long-term data using cost intensive equipment. Recently, a wireless smart sensor network (WSSN) has drawn significant attention for transportation infrastructure monitoring because of its merits in low cost, easy installation, and versatile on-board computation capability. In this paper, a rapid wireless displacement monitoring system, wireless hybrid sensor (WHS), has been developed to monitor displacement of expansion joints of bridges. The WHS has been calibrated for both static and dynamic displacement measurement in laboratory environment, and deployed on an in-service highway bridge to demonstrate rapid expansion joint monitoring. The test-bed is a continuous steel girder bridge, the Founders Bridge, in East Hartford, Connecticut. Using the WHS system, the static and dynamic displacement of the expansion joint has been measured. The short-term displacement trend in terms of temperature is calculated. With the WHS system, approximately 6% of the time has been spent for installation, and 94% of time for the measurement showing strong potential of the developed system for rapid displacement monitoring.

• Smart Structures and Systems
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• 제15권1호
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• pp.151-167
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• 2015

Instrumentation on structural health monitoring system imposes critical issues for applying the structural monitoring system to real world structures, for which not only on the configuration and geometry, but also aesthetics on the system to be monitored should be considered. To illustrate this point, two real world structural health monitoring systems, the structural health monitoring system of Shenzhen Vanke Center and the structural health monitoring system of Shenzhen Bay Stadium in China, are presented in the paper. The instrumentation on structural health monitoring systems of real world structures is addressed by providing the description of the structure, the purpose of the structural health monitoring system implementation, as well as details of the system integration including the installations on the sensors and acquisition equipment and so on. In addition, an intelligent algorithm on stress identification using measurements from multi-region is presented in the paper. The stress identification method is deployed using the fuzzy pattern recognition and Dempster-Shafer evidence theory, where the measurements of limited strain sensors arranged on structure are the input data of the method. As results, at the critical parts of the structure, the stress distribution evaluated from the measurements has shown close correlation to the numerical simulation results on the steel roof of the Beijing National Aquatics Center in China. The research work in this paper can provide a reference for the design and implementation of both real world structural health monitoring systems and intelligent algorithm to identify stress distribution effectively.

• Smart Structures and Systems
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• 제15권2호
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• pp.395-408
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• 2015

This study aims to propose a Bayesian approach to consider changes in temperature and vehicle weight as environmental and operational factors for vibration-based long-term bridge health monitoring. The Bayesian approach consists of three steps: step 1 is to identify damage-sensitive features from coefficients of the auto-regressive model utilizing bridge accelerations; step 2 is to perform a regression analysis of the damage-sensitive features to consider environmental and operational changes by means of the Bayesian regression; and step 3 is to make a decision on the bridge health condition based on residuals, differences between the observed and predicted damage-sensitive features, utilizing 95% confidence interval and the Bayesian hypothesis testing. Feasibility of the proposed approach is examined utilizing monitoring data on an in-service bridge recorded over a one-year period. Observations through the study demonstrated that the Bayesian regression considering environmental and operational changes led to more accurate results than that without considering environmental and operational changes. The Bayesian hypothesis testing utilizing data from the healthy bridge, the damage probability of the bridge was judged as no damage.

• Smart Structures and Systems
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• 제5권2호
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• pp.193-207
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• 2009

A framework for structural health monitoring (SHM) systems is presented utilizing a recent 3.5 generation mobile telecommunication technology, HSDPA (High Speed Downlink Packet Access). It may be effectively applied to monitoring bridges, cut-slopes, and other facilities located in rural areas where the conventional Internet service is not readily available, since HSDPA is currently commercialized in 86 countries to make the Internet access possible in anywhere the mobile phone service is available. The proposed SHM framework is also incorporating remote desktop software to have remote control/operation of the SHM systems. The feasibility of the proposed framework has been demonstrated by field tests on a highway bridge in operation. One can expect that fast advances in the mobile telecommunication technology will further enhance the performance of the SHM network using the proposed framework for bridges and other facilities located in remote areas without the conventional wired Internet service.

• 국제초고층학회논문집
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• 제2권3호
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• pp.179-192
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• 2013

The lack of systematic validation for the design process supporting tall buildings motivated the authors' research groups and their collaborators to found the Chicago Full-Scale Monitoring Program over a decade ago. This project has allowed the sustained in-situ observation of a collection of tall buildings now spanning worldwide. This paper overviews this program and the lessons learned in the process, ranging from appropriate technologies for response measurements to the factors influencing accurate prediction of dynamic properties all the way to how these properties then influence the prediction of response using wind tunnel testing and whether this response does indeed correlate with in-situ observations. Through this paper, these wide ranging subjects are addressed in a manner that demonstrates the importance of continued promotion and expansion of full-scale monitoring efforts and the ways in which these programs can provide true value-added to building owners and managers.

• 한국환경과학회지
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• 제15권8호
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• pp.737-744
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• 2006

Present study was designed to characterize the concentrations of major roadside air pollutants in Daegu and to compare with those of Seoul and Busan. Evaluated were the exceedance frequence of mean concentrations of target compounds(CO, NO$_2$, O$_3$, PM$_{10}$, SO$_2$) and the relationship for time variation. Two air pollution monitoring stations(one roadside station and one residential station) in Daegu were selected for this study. In addition, one roadside monitoring station from each of Seoul and Busan was chosen for the comparison of Daegu monitoring stations. The data analyzed in the current study were collected from 1998 to 2000 by Daegu Regional Environmental Management Office. The roadside concentrations of NO2 and PM to and the exceedance frequency of ambient air standard levels in Daegu were higher than those of Seoul and Busan. Except 03, the roadside concentrations of all target compounds showed following three distinguished patterns; first, possibly due to increased traffic density, the concentrations increased from 0500 to 0900(LST), second, the concentrations decreased from 0900 to 1700(LST) possibly due to the increased wind velocity and decreased traffic density, and finally, increased traffic density, the concentrations increased again from 1700 to 2100(LST). An implication was that major air pollution sources shifted from residential area to road-area during rush hours.

• 한국환경과학회지
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• 제26권9호
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• pp.1073-1080
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• 2017

Manufacturing and technology industries produce large amounts of air pollutants. Ulsan Metropolitan City, South Korea, is well-known for its large industrial complexes; in particular, the concentration of $SO_2$ here is the highest in the country. We assessed $SO_2$ monitoring sites based on conditional and joint entropy, because this is a common method for determining an optimal air monitoring network. Monthly $SO_2$ concentrations from 12 air monitoring sites were collected, and the distribution of spatial locations was determined by kriging. Mean absolute error, Root Mean Squared Error (RMSE), bias and correlation coefficients were employed to evaluate the considered algorithms. An optimal air monitoring network for Ulsan was suggested based on the improvement of RMSE.

• 한국해양공학회지
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• 제18권1호
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• pp.10-15
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• 2004

For effective conservation of the oceans and harbors, long-term and systematic development of the ocean and harbor monitoring system is essential. A monitoring system capable of real-time and accurate data acquisition is necessary for dealing with the level of contamination by situations, such as red tide and foods. This paper introduces an effective and economical real-time harbor environmental monitoring system that utilizes PCS wireless data communication technology. The monitoring system has various functions, such as multiple communication, TCP/IP protocol for wireless internet access, system time synchronization, and bi-directional communication between the measuring device and the server. The system has been implemented at Shinseondae harbor pier in Busan to validate the system's stability and effectiveness in data acquisition. The acquired real-time ocean and harbor environmental data is expected to have a large effect, when shared with the public through the Internet.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.63-68
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• 2003

For effective conservation of ocean and harbor, long-term and systematic development of the ocean and harbor monitoring system is essential. The monitoring system capable of real-time and accurate data acquisition is necessary for dealing with contamination such as red tide and the flood. This paper introduces the effective and economical real-time harbor environmental monitoring system that utilizes PCS wireless data communication technology. The monitoring system has various functions such as multiple communication, TCP/IP protocol for wireless internet access, system time synchronization, bi-directional communication between the measuring device and the server. The system has been implemented at Shinseondae harbor pier in Busan to validate the systems stability and effectiveness in data acquisition. The acquired real-time ocean and harbor environmental data is expected to have a large effect, when shared by public through internet.

• 지질공학
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• 제16권4호
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• pp.351-357
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• 2006

상수원으로 사용하고 있는 주요 하천으로의 위해물질의 유입은 정수장에서의 고도기술을 요구하게 된다. 그러므로 산업폐수로부터 방류되는 이들 미량유해화학물질의 모니터링을 적절하게 하는 것은 위해도 저감 뿐 만 아니라 하천관리의 경제성도 증가시킬 수 있다. 본 연구를 통해 모니터링 한 여러 미량 유해화학물질 중에서 산업폐수의 방류수에서 검출된 오염물질 중 가장 주요한 항목은 Hexachlorobutadiene 였다. 그러나 반도체, 전기/전자 및 금속조립 산업폐수로 구성된 Group II에서는 모든 항목이 불검출로 나타났다. 따라서 향후 상수원 수질개선 및 보호를 하기 위해 모니터링 항목을 선정하는데 있어서는 해당 수계로 부하되는 물질들의 특성과 거동을 제대로 파악하기 위한 사전모니터링을 실시하여 시간, 노력 및 경제적인 손실을 최소화하여 효율적인 상수원관리를 해야 한다.