• Environmental Analysis Health and Toxicology
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• v.30
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• pp.10.1-10.14
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• 2015

Recent cohort studies have relied on exposure prediction models to estimate individual-level air pollution concentrations because individual air pollution measurements are not available for cohort locations. For such prediction models, geographic variables related to pollution sources are important inputs. We demonstrated the computation process of geographic variables mostly recorded in 2010 at regulatory air pollution monitoring sites in South Korea. On the basis of previous studies, we finalized a list of 313 geographic variables related to air pollution sources in eight categories including traffic, demographic characteristics, land use, transportation facilities, physical geography, emissions, vegetation, and altitude. We then obtained data from different sources such as the Statistics Geographic Information Service and Korean Transport Database. After integrating all available data to a single database by matching coordinate systems and converting non-spatial data to spatial data, we computed geographic variables at 294 regulatory monitoring sites in South Korea. The data integration and variable computation were performed by using ArcGIS version 10.2 (ESRI Inc., Redlands, CA, USA). For traffic, we computed the distances to the nearest roads and the sums of road lengths within different sizes of circular buffers. In addition, we calculated the numbers of residents, households, housing buildings, companies, and employees within the buffers. The percentages of areas for different types of land use compared to total areas were calculated within the buffers. For transportation facilities and physical geography, we computed the distances to the closest public transportation depots and the boundary lines. The vegetation index and altitude were estimated at a given location by using satellite data. The summary statistics of geographic variables in Seoul across monitoring sites showed different patterns between urban background and urban roadside sites. This study provided practical knowledge on the computation process of geographic variables in South Korea, which will improve air pollution prediction models and contribute to subsequent health analyses.

• Wind and Structures
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• v.20 no.6
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• pp.763-791
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• 2015

"Wind and Ports" is a European project that has been carried out since 2009 to handle wind forecast in port areas through an integrated system made up of an extensive in-situ wind monitoring network, the numerical simulation of wind fields, the statistical analysis of wind climate, and algorithms for medium-term (1-3 days) and short term (0.5-2 hours) wind forecasting. The in-situ wind monitoring network, currently made up of 22 ultrasonic anemometers, provides a unique opportunity for detecting high resolution thunderstorm records and studying their dominant characteristics relevant to wind engineering with special concern for wind actions on structures. In such a framework, the wind velocity of thunderstorms is firstly decomposed into the sum of a slowly-varying mean part plus a residual fluctuation dealt with as a non-stationary random process. The fluctuation, in turn, is expressed as the product of its slowly-varying standard deviation by a reduced turbulence component dealt with as a rapidly-varying stationary Gaussian random process with zero mean and unit standard deviation. The extraction of the mean part of the wind velocity is carried out through a moving average filter, and the effect of the moving average period on the statistical properties of the decomposed signals is evaluated. Among other aspects, special attention is given to the thunderstorm duration, the turbulence intensity, the power spectral density and the integral length scale. Some noteworthy wind velocity ratios that play a crucial role in the thunderstorm loading and response of structures are also analyzed.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.3
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• pp.73-83
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• 2010

A technology using continuous fiber soil reinforcement system for the creation of ecological restoration in a damaged area has been developed and introduced. The continuous fiber soil reinforcement system (Geofiber system) is an environmentally friendly slope protection technique that continuous fiber soil reinforced layers are constructed with green plantation on cut slope. The characteristics of this system in terms of the strength and hydraulic performance, and the vegetation were investigated in this study. The main objectives of this comparative study was to quantify the potential contribution of geofiber system for the revegetation on the cut slope in a damaged area. A Geofiber system was constructed to reinforce the lower layer of slopes and revegetation methods including wood chips were carried out on the upper layer by machineries. The results of monitoring during 3 years on cut slopes were as follows : 1) All the quadrat existed in the proper range for vegetation. 2) Species richness was 4.4 (site-1) and 18.5 (site-2) respectively. 3) The averaged coverage rates of quadrats was 90%. It is remarkable that the continuous fiber soil reinforcement system would be capable of applying to a damaged area and also would serve maintaining a healthier environment for floras. However, it behooves to continue monitoring on succession of vegetation for ecological restoration.

• Smart Structures and Systems
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• v.6 no.3
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• pp.183-196
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• 2010

Monitoring and economical design of alternative energy generators such as wind turbines is becoming increasingly critical; however acquisition of the dynamic output data can be a time-consuming and costly process. In recent years, low-cost wireless sensors have emerged as an enabling technology for structural monitoring applications. In this study, wireless sensor networks are installed in three operational turbines in order to demonstrate their efficacy in this unique operational environment. The objectives of the first installation are to verify that vibrational (acceleration) data can be collected and transmitted within a turbine tower and that it is comparable to data collected using a traditional tethered system. In the second instrumentation, the wireless network includes strain gauges at the base of the structure. Also, data is collected regarding the performance of the wireless communication channels within the tower. In both turbines, collected wireless sensor data is used for off-line, output-only modal analysis of the ambiently (wind) excited turbine towers. The final installation is on a turbine with embedded braking capabilities within the nacelle to generate an "impulse-like" load at the top of the tower. This ability to apply such a load improves the modal analysis results obtained in cases where ambient excitation fails to be sufficiently broad-band or white. The improved loading allows for computation of true mode shapes, a necessary precursor to many conditional monitoring techniques.

• Hwankyungkyoyuk
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• v.5 no.1
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• pp.112-137
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• 1993

As the concern with the creation of environmental problems and regulations about them becomes internationally growing, environmental cooperations with countries concerned are emerging as the first item on the political agenda. In case of South Korea, cooperations with countries in the Asian region is needed urgently. In particular, cooperations with North Korea will be an important factor to reunify the Korean peninsula as well as to solve environmental problems in South Korea. Accordingly, it is necessary to seek feasible alternatives and possibilities of coping with international environment in South and North Korea. This study is limited to literature study based on collecting materials and the testimony of former residents in North Korea. The period of study ranges from May to December in 1992. The research findings show the following environmental problems and alternatives : It is recognized in South Korea that the creation of environmental problems is product of economic development. Currently, the Korean government makes an effort to revise environmental administration and law, to encourage environmental education, and to proceed with environmental technology policies by establishing environmental policies together with economic development plans. North Korea ascribes the cause of environmental problems to colonial exploitation by Japan and the U.S. Environmental pollutants in North Korea is relatively less than South Korea, provisions such as environmental conservation movement, environmental education, and environmental administration and law are not well organized in the country. However, North korea will speed up its economic development to solve economic crises. Therefore, it is expected that industrial wastes, corrosion of nature, and water pollution will result in serious environmental problems. The fields expected to cooperate with South and North Korea are in the following : South Korea may adopt the model of the former East and West Germany and proceed to cooperate with North Korea in public sector as well as private sector. The possible programs are such as academic exchange to conserve environment, joint research in the area of the Demilitarized Zone, conservation of ecosystems around Imjin and Pukhan Rivers, South Korea's support of advanced environmental technology and industrial and financial aid to North Korea. Conflicts between countries concerned in the North East Asian region will be caused by the responsibilities of pollutions because of the seashore development of the Yellow Sea by South Korea and increasing seashore industrial complexes around the Yellow Sea in China, Therefore, it is desirable that the two countries will participate in organizations related to environment. Joint projects between South and North Korea will be as follows : 1. Construction of long-range monitoring system : 2. Investigation of the state of pollutions around the Yellow Sea and alternatives : 3. Construction of joint monitoring system to regulate the movement of pollutants : 4. Cooperation of environmental technology and exchange of information ; and 5. Support of Cooperation of environment in private sector. Efforts to cooperate with North korea is expected to overcome differences between the two countries as well as to encourage unification of the korean peninsula, which will lead to reducing the cost of environmental recovery. These efforts will also contribute to the maintenance for peace and stability on the korean peninsula as well as in the North East Asian region.

• Smart Structures and Systems
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• v.29 no.4
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• pp.625-640
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• 2022

Maglev rail joints are vital components serving as connections between the adjacent F-type rail sections in maglev guideway. Damage to maglev rail joints such as bolt looseness may result in rough suspension gap fluctuation, failure of suspension control, and even sudden clash between the electromagnets and F-type rail. The condition monitoring of maglev rail joints is therefore highly desirable to maintain safe operation of maglev. In this connection, an online damage detection approach based on three-dimensional (3D) convolutional neural network (CNN) and time-frequency characterization is developed for simultaneous detection of multiple damage of maglev rail joints in this paper. The training and testing data used for condition evaluation of maglev rail joints consist of two months of acceleration recordings, which were acquired in-situ from different rail joints by an integrated online monitoring system during a maglev train running on a test line. Short-time Fourier transform (STFT) method is applied to transform the raw monitoring data into time-frequency spectrograms (TFS). Three CNN architectures, i.e., small-sized CNN (S-CNN), middle-sized CNN (M-CNN), and large-sized CNN (L-CNN), are configured for trial calculation and the M-CNN model with excellent prediction accuracy and high computational efficiency is finally optioned for multiple damage detection of maglev rail joints. Results show that the rail joints in three different conditions (bolt-looseness-caused rail step, misalignment-caused lateral dislocation, and normal condition) are successfully identified by the proposed approach, even when using data collected from rail joints from which no data were used in the CNN training. The capability of the proposed method is further examined by using the data collected after the loosed bolts have been replaced. In addition, by comparison with the results of CNN using frequency spectrum and traditional neural network using TFS, the proposed TFS-CNN framework is proven more accurate and robust for multiple damage detection of maglev rail joints.

• The Journal of Engineering Geology
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• v.16 no.2 s.48
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• pp.145-152
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• 2006

Industry development caused numerical and quantitative increase of noxious chemical substances that contain risk assessment in water resources. For use of efficient water resources a pre-treatment of contaminant source which is flowed in water resources is recognized in essential process. Therefore, the discharged water quality from discharged company began to control contaminant by total amount of pollutant in domestic. However, to estimate closely chemical substances it is not proved up to now, monitoring is very important. This study achieved a monitoring of micro noxious chemical substance by fiber and chemistry industrial wastewater inflow to examine risk assessment of the water system of Nakdong river. Chloroform was measured highest among volatile organic compounds (VOCs) that the results of water quality of influent and effluent are detected from 7 companies of study area. The other side, because measured value of detected chloroform is indefinite detection level in the same company, it is difficulty in management of water quality. However it may not be much effects of the water system of Nakdong river because these company's effluent is high treatment efficiency of chloroform (more than 88%) in sewage treatment plant. On the other hand, in the investigated results for the European Union specified priority substance that is detected to relationship influent and effluent from fiber/chemistry associated industries, these substances were not detected and domestic data was hardly referred. Therefore, data construction of continuous monitoring about this water quality may have to be achieved certainly to utilize as country policy.

• Journal of Environmental Health Sciences
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• v.47 no.1
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• pp.45-54
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• 2021

Objectives: This study evaluated the odor around an industrial complex area (#1-#5) and the operational effects of the Odor Monitoring System in Seo-gu in Daegu City. Methods: Samples were collected from November 2012 to December 2018 and were analyzed for complex odor. The odor occurrence rate and the odor reduction rate were calculated. Results: In 2018, the mean concentration of complex odor decreased 20.9% and the odor occurrence rate decreased from 65.0 to 27.5% around the industrial complex area (#1-#5) in Seo-gu compared to 2013. After the operation of the Odor Monitoring System, the standard excess rate (3.0%→40.8%) and the excess concentration of complex odor (1,442→4,304) increased at odor-emitting workplaces. In addition, the mean concentration of complex odor (15.9%) and the odor occurrence rate (60.6%→32.9%) around the industrial complex area (#1-#5) and the number of odor complaints (23.4%) in Seo-gu decreased. Conclusion: In order to reduce the odor around the industrial complex area, it is important to improve the odor emitting facilities. The Odor Monitoring System uses scientific and systematic monitoring methods that can help control and manage the odor emission facilities.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.67-76
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• 2002

Data-Acquisition systems are widely used in Photovoltaic(PV) system application in order to analyze and optimize the performance of PV systems. In this paper, the development of a computer-based data-acquisition system and its application are described. The proposed Computer-based data-acquisition System consists of a set of sensors for measuring both environmental and electrical parameters. The collected data are first conditioned and then interfaced to PC using a data-acquisition card. The Labview program was used to further process, display on the monitor at real time and store on the hard disk. We designed and installed two stand-alone PV systems to supply different loads, which in this case a Low Pressure Sodium(LPS) 55 [W] lamp and a electrodless 55 [W] lamp. When the proposed data acquisition system is applied on the designed PV systems, Optimized system operation methods are investigated to confirm a stable load availability and extend battery life time.

• Smart Structures and Systems
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• v.33 no.5
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• pp.375-383
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• 2024

Infrastructure facilities contain various pipe systems, which can be considerably damaged by external loads such as earthquakes. Therefore, structural health monitoring (SHM) and safety assessment of pipes are crucial. Digital twin technology for SHM of pipes is important in the industry. This study proposes a digital twin system that estimates the behavior, stress, and external load of real-scale pipes in real time under simultaneous seismic and external loads using a minimum number of sensors. Vibration tests were performed to construct the digital twin system, and a numerical model was developed that considered the dynamic characteristics of a target pipe. Moreover, a reduced-order modeling technique of a numerical model was applied to enhance its real-time performance. The digital twin system successfully estimated the response of the pipe at all points. Verification of the digital twin system was performed by comparing it with the experimental parameters of a real-scale pipe. The proposed digital twin system can help enhance SHM and system's maintenance.