• Korean Journal of Remote Sensing
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• v.37 no.6_1
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• pp.1517-1526
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• 2021

With the recent global and domestic development of Earth observation satellites, the applications of satellite images have been widened. Research for improving the geometric accuracy of satellite images is being actively carried out. This paper studies the possibility of automated ground control point (GCP) generation for CAS-4 satellite, to be launched in 2025 with the capability of image acquisition at 5 m ground sampling distance (GSD). In particular, this paper focuses to check whether GCP chips with 25 cm GSD established for CAS-1 satellite images can be used for CAS-4 and to check whether optimalspatial resolution for matching between CAS-4 images and GCP chips can be determined to improve matching performance. Experiments were carried out using RapidEye images, which have similar GSD to CAS-4. Original satellite images were upsampled to make satellite images with smaller GSDs. At each GSD level, up-sampled satellite images were matched against GCP chips and precision sensor models were estimated. Results shows that the accuracy of sensor models were improved with images atsmaller GSD compared to the sensor model accuracy established with original images. At 1.25~1.67 m GSD, the accuracy of about 2.4 m was achieved. This finding lead that the possibility of automated GCP extraction and precision ortho-image generation for CAS-4 with improved accuracy.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.5
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• pp.100-112
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• 2021

With the advent of big data, traffic prediction has been developed based on historical data analysis methods, but this method deteriorates prediction performance when a traffic incident that has not been observed occurs. This study proposes a method that can compensate for the reduction in traffic prediction accuracy in traffic incidents situations by hybrid approach of machine learning and traffic simulation. The blind spots of the data-driven method are revealed when data patterns that have not been observed in the past are recognized. In this study, we tried to solve the problem by reinforcing historical data using traffic simulation. The proposed method performs machine learning-based traffic prediction and periodically compares the prediction result with real time traffic data to determine whether an incident occurs. When an incident is recognized, prediction is performed using the synthetic traffic data generated through simulation. The method proposed in this study was tested on an actual road section, and as a result of the experiment, it was confirmed that the error in predicting traffic state in incident situations was significantly reduced. The proposed traffic prediction method is expected to become a cornerstone for the advancement of traffic prediction.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.3
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• pp.5-16
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• 2021

In this study, the applicability of the MBR(Membrane Bio Reactor) process of oxygen dissolve was evaluated through comparison and evaluation of the efficiency of oxygen dissolve device and conventional aeration device in the explosive tank within the MBR process. The organic matter and ammonia oxidation by oxygen dissolve device were evaluated, and the efficiency of persaturation was evaluated by applying real waste water (anaerobic digester effluent treatement from food waste). SCOD and ammonia removal rates for oxygen dissolve device and conventional aeration device methods were similar. However, it was determined that the excess sludge treatment cost could be reduced as the yield of microorganisms by oxygen dissolve device is about 0.03 g MLSS-produced/g SCOD-removed lower than that of microorganisms by conventional aeration device. The removal rates of high concentrations of organic matter (4,000 mg/L) and ammonia (1,400 mg/L) in anaerobic digester effluent treatment from food waste were compared to the conventional aeration device and the oxygen dissolve device organic matter removal rate was approximately 13% higher than that of the conventional aeration device. In addition, for MLSS, the conventional aeration device was 0.3 times higher than for oxygen dissolve device. This is believed to be due to the high progress of sludge autooxidation because the dissolved oxygen is sufficiently maintained and supplied in the explosive tank for oxygen dissolve device. Therefore, it was determined that the use of oxygen dissolve device will be more economical than conventional aeration device as a way to treat wastewater containing high concentrations of organic matter.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.529-536
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• 2021

In this study, nano-silica and nano-titanium were selected to determine the possibility of applying the binder to reactive nano materials. The basic characteristics of the nano material candidate group were reviewed. and the reactivity of nano materials was reviewed through K-value. The reactivity of the nano silicate materials was measured to be high. Therefore, as a final candidate group, nano silicate materials were selected. The finally selected reactive nano material was reviewed for its usability as a construction binder. The mechanical properties and unit weight of cement paste were reviewed using silica fume and blast furnace slag and nano materials. When cement composites with nano silicate materials, it was confirmed that it was effective in improving the mechanical performance and decrease the unit weight of cement composites.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.83-91
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• 2021

In this study, to improve the connection performance between the existing reinforced concrete (R/C) frame and the strengthening member, we proposed a new H-section steel frame with elastic pad (HSFEP) system for seismic rehabilitation of existing medium-to-low-rise reinforced concrete (R/C) buildings. This HSFEP strengthening system exhibits an excellent connection performance because an elastic pad is installed between the existing structure and reinforcing frame. The method shows a strength design approach implemented via retrofitting, to easily increase the ultimate lateral load capacity of R/C buildings lacking seismic data, which exhibit shear failure mechanism. Two full-size two-story R/C frame specimens were designed based on an existing R/C building in Korea lacking seismic data, and then strengthened using the HSFEP system; thus, one control specimen and one specimen strengthened with the HSFEP system were used. Pseudodynamic tests were conducted to verify the effects of seismic retrofitting, and the earthquake response behavior with use of the proposed method, in terms of the maximum response strength, response displacement, and degree of earthquake damage compared with the control R/C frame. Test results revealed that the proposed HSFEP strengthening method, internally applied to the R/C frame, effectively increased the lateral ultimate strength, resulting in reduced response displacement of R/C structures under large scale earthquake conditions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.75-82
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• 2021

The objective of this study is to examine the loss of prestressing stress in the developed prestressing reinforcing units using steel bar and pipe (SP). The main parameters were the reinforcing bar type, the magnitude of prestressed force, and prestressing method. The test results showed that the loss of prestressing stress for SP was highest in the initial prestressing step, which was higher for the compression introduction typed specimens than tension introduction typed specimens. The loss of prestressing stress of SP made with P800 was 1.6% for the compression introduction typed specimen with 0.8f_y, which was lowest than the other specimens. Meanwhile, the relaxation of SP with the respect to the time ranged between 0.4 and 1.9%, irrespective of SP material type, the magnitude of prestressed force, and prestressing method. These values were less than 2.5%, which is the maximum value for the relaxation of prestressed reinforcing steel bars in design codes. Consequently, considering the loss of stress developed in the initial prestressing step, the developed SP material type, prestressing introduction method, and magnitude are recommended to be P800, compression introduction type, and 0.8f_y.

• Korean Journal of Remote Sensing
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• v.37 no.2
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• pp.177-198
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• 2021

Existing change detection researches have been focused on changes of land use and land cover (LULC), damaged areas, or large vegetated and water regions. On the other hands, increased temporal and spatial resolution of satellite images are strongly suggesting the feasibility of change detection of small objects such as vehicles and ships. In order to check the feasibility, this paper analyzes the performance of existing pixel-based change detection methods over small objects. We applied pixel differencing, PCA (principal component analysis) analysis, MAD (Multivariate Alteration Detection), and IR-MAD (Iteratively Reweighted-MAD) to Kompsat-3A and Google Map images taken within 10 days. We extracted ground references for changed and non-changed small objects from the images and used them for performance analysis of change detection results. Our analysis showed that MAD and IR-MAD, that are known to perform best over LULC and large areal changes, offered best performance over small object changes among the methods tested. It also showed that the spectral band with high reflectivity of the object of interest needs to be included for change analysis.

• The Journal of the Korea Contents Association
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• v.19 no.8
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• pp.667-676
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• 2019

In recent years, the occurrence of life and violent crime in the city centered on crime-prone areas has become a big issue, raising the public interest in safety from crime has been higher than ever. As the initial response to crime and the importance of crime prevention are emerging, the government is preparing various measures such as crime prevention service using advanced technology. This project is a demonstration project to select specific target sites and apply that on a trial basis with the main purpose of commercialization of intelligent crime prevention technologies and services. In order to spread the business through the demonstration project, it is expected that the practical economic evaluation as well as the academic and practical value of the project will have a great significance. In this study, the purpose of this research is to derive economic feasibility through technologies and services to be implemented in Indokwon district of Anyang city, which is selected demonstration site of the intelligent security, to promote the spread of business and contribute to the policy activation.

• The Journal of the Korea Contents Association
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• v.18 no.12
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• pp.646-659
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• 2018

This study proposed "Reservoir Park", which added disaster prevention function to urban green spaces such as city parks through domestic and overseas related laws review, case studies, field trips. This is a combination of urban parks and reservoirs as urban planning facilities, which can provide both space for daily use by urban residents and disaster mitigation functions in case of emergency. In order to prevent flooding in urban areas due to climate change, facilities should be installed in the form of parks, etc., as the reservoir facility should be systematically reviewed together with urban planning facilities. However it was found that the reservoir park was not clear as a theme park. In this study, the types of storage facilities in urban areas were reclassified into five types of storage parks reflecting the characteristics of urban green spaces through domestic case studies and field trips. The classification of the reservoir parks is classified into 5 kinds such as ecological type, vegetation cover type, exercise facility type, underground burial type and hybrid type based on groundwater level, human use, and reservoir size. This classification system can be used to determine the types of facilities to be built after designating the location of future storage facilities.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.2
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• pp.29-43
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• 2019

The calibration of microscopic traffic simulation models has received much attention in the simulation field. Although no standard has been established for it, a genetic algorithm (GA) has been widely employed in recent literature because of its high efficiency to find solutions in such optimization problems. However, the performance still falls short in simulation analyses to support fast decision making. This paper proposes a new calibration procedure using a dual GA and central composite design (CCD) in order to improve the efficiency. The calibration exercise goes through three major sequential steps: (1) experimental design using CCD for a quadratic response surface model (RSM) estimation, (2) 1st GA procedure using the RSM with CCD to find a near-optimal initial population for a next step, and (3) 2nd GA procedure to find a final solution. The proposed method was applied in calibrating the Gipps car-following model with respect to maximizing the likelihood of a spacing distribution between a lead and following vehicle. In order to evaluate the performance of the proposed method, a conventional calibration approach using a single GA was compared under both simulated and real vehicle trajectory data. It was found that the proposed approach enhances the optimization speed by starting to search from an initial population that is closer to the optimum than that of the other approach. This result implies the proposed approach has benefits for a large-scale traffic network simulation analysis. This method can be extended to other optimization tasks using GA in transportation studies.