• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.621-626
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• 2021

In this study, data on the study site for apartment construction was acquired, and the quantity of construction waste was calculated using a drone and mobile 3D laser scanner. The accuracy of the drone was 0.034 to 0.064m in the horizontal and vertical directions, respectively, and the mobile 3D Laser Scanner showed an accuracy of 0.018 to 0.049m in the horizontal direction, respectively. These results suggest that it is possible to construct spatial information using a drone and mobile 3D laser scanner with a value within the allowable accuracy of 1:1,000 digital terrain. The volume of construction waste calculated using the mobile 3D laser scanner data was 70,797㎥. It was possible to calculate the volume on the side of the building or some facilities that appeared as shaded areas in the drone outcomes. In addition, modeling was performed for view analysis of the apartments scheduled to be constructed and the terrain-based modeling results of the surrounding buildings. In the future, data construction and accuracy evaluation using mobile 3D laser scanners will be conducted. In addition, additional research comparing existing methods and work processes will be carried out, and the efficiency of mobile 3D laser scanners in the field of spatial information construction can be presented.

• Ecology and Resilient Infrastructure
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• v.8 no.1
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• pp.9-21
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• 2021

In this study, fish and flow surveys were conducted at 12 survey points to calculate the fish habitat suitability index of Miho Stream in the Geum River Water System. The field surveys were conducted four times from September 2019 to May 2020. The results show the presence of 8 families, 37 species, and 5,754 individuals. The number of water purification species that preferred waters with a low flow rate was the highest. The habitat suitability index was calculated according to the Washington Department of Fish and Wildlife method based on the populations collected at various water depths and flow rate sections and the flow rate survey results. For the dominant species, Zacco platypus and swimming species, the results were compared by calculating at Gasan Bridge and Palgye Bridge at the upper stream. The single species showed no significant difference between the upstream and downstream at water depths of 0.1 - 0.5 m and flow rates of 0.2 - 0.5 m/s. The species swimming ability was similarly calculated at water depths of 0.2 - 0.5 m and flow rates of 0.2 - 0.5 m/s. The dominant species, Pyramid, had a wide range of physical habitats. The habitat suitability index between the swimming species was similarly calculated. These results can be effectively used as basic data for calculating the environmental ecological flow rate and establishing a river restoration plan of the Miho Stream.

• Journal of the Korean Institute of Gas
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• v.24 no.6
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• pp.18-27
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• 2020

This study presents flow assurance analysis in subsea pipeline considering system availability of topside in LNG-FPSO. A hydrate management strategy was established, which consisted of PVCap experiments, system availability analysis of LNG-FPSO topside, hydrate risk analysis in the pipeline, and calculation of PVCap injection concentration. The experimental data required for the determination of PVCap injection concentration were obtained by measuring the hydrate induction time of PVCap at the subcooling temperatures of 6.1, 9.2, and 12.1℃. The availability of LNG-FPSO topside system for 20 years was 89.3%, and the longest downtime of 50 hours occurred 2.9 times per year. The subsea pipeline model for multiphase flow simulation was created using field geometry data. As a result of risk analysis of hydrate plugging using subsea pipeline model, hydrate was formed at the end of flowline in 23.2 hours under the condition of 50 hours shutdown. The injection concentration of PVCap was determined based on the PVCap experiment results. The hydrate plugging in subsea pipeline of LNG-FPSO can be completely prevented by injecting PVCap 0.25 wt% 2.9 times per year.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.480-493
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• 2021

Since the generalized Hoek-Brown criterion (GHB) provides an efficient way of identifying its strength parameter values with the consideration of in-situ rock mass condition via Geological Strength Index (GSI), this criterion is recognized as one of the standard rock mass failure criteria in rock mechanics community. However, the nonlinear form of the GHB criterion makes its mathematical treatment inconvenient and limits the scope of its application. As an effort to overcome this disadvantage of the GHB criterion, the explicit approximate analytical equations for the minimum principal stress, which is associated with the maximum principal stress at failure, are formulated based on the Taylor polynomial approximation of the original GHB criterion. The accuracy of the derived approximate formula for the minimum principal stress is verified by comparing the resulting approximate minimum principal stress with the numerically calculated exact values. To provide an application example of the approximate formulation, the equivalent friction angle and cohesion for the expected plastic zone around a circular tunnel in a GHB rock mass are calculated by incorporating the formula for the approximate minimum principal stress. It is found that the simultaneous consideration of the values of mi, GSI and far-field stress is important for the accurate calculation of equivalent Mohr-Coulomb parameter values of the plastic zone.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.40 no.3
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• pp.169-175
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• 2022

Korea's construction industry has a shortage and aging of construction manpower, low productivity compared to other industries, and a high rate of industrial accidents. The Ministry of Land, Infrastructure and Transport is preparing for the 4th industrial revolution and is expanding investment in construction automation and innovative growth engines to improve productivity in the construction industry. In order for new technologies to be utilized in the road construction field, the accuracy of the technologies and the applicability of each type of work must be evaluated. In this study, the accuracy of the mobile mapping system was tried to verify based on the relevant work regulations, and to suggest the applicability of the mobile mapping system to high-speed driving tracks through data acquisition and analysis on road construction sites. The accuracy of the equipment used in the study was verified in accordance with the relevant work regulations, and the possibility of applying the mobile mapping system used for the study to road construction surveying was presented with a maximum error of less than 10cm in the horizontal and vertical directions. In addition, the possibility of utilizing the road construction survey using the mobile mapping system was presented through comparison with the existing method for data acquisition time for construction surveying, production of construction status survey results, and calculation of heatmap and earthworks. In the future, the use of construction status surveying of the mobile mapping system will greatly improve the efficiency of construction work.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1141-1180
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• 2022

The application of satellite imageries has increased in the field of hydrology and water resources in recent years. However, challenges have been encountered on obtaining accurate evapotranspiration and soil moisture. Therefore, present researches have emphasized the necessity to obtain estimations of satellite-based evapotranspiration and soil moisture with related development researches. In this study, we presented the research status in Korea by investigating the current trends and methodologies for evapotranspiration and soil moisture. As a result of examining the detailed methodologies, we have ascertained that, in general, evapotranspiration is estimated using Energy balance models, such as Surface Energy Balance Algorithm for Land (SEBAL) and Mapping Evapotranspiration with Internalized Calibration (METRIC). In addition, Penman-Monteith and Priestley-Taylor equations are also used to estimate evapotranspiration. In the case of soil moisture, in general, active (AMSR-E, AMSR2, MIRAS, and SMAP) and passive (ASCAT and SAR)sensors are used for estimation. In terms of statistics, deep learning, as well as linear regression equations and artificial neural networks, are used for estimating these parameters. There were a number of research cases in which various indices were calculated using satellite-based data and applied to the characterization of drought. In some cases, hydrological cycle factors of evapotranspiration and soil moisture were calculated based on the Land Surface Model (LSM). Through this process, by comparing, reviewing, and presenting major detailed methodologies, we intend to use these references in related research, and lay the foundation for the advancement of researches on the calculation of satellite-based hydrological cycle data in the future.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.741-749
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• 2022

Radiography-Testing that verify the quality of welding structures without destruction are overwhelmingly used in industries, but many safety precautions are required as radiation is used. The workers for Radiography-Testing perform the inspection by moving the Iridium-192 radiation source embedded in the transport container of the gamma-ray irradiator within or outside the facility. The general facility is completely blocked about radiation from the outside with thick concrete, but if it is difficult for worker to handle object of inspection, facilities ceiling can be opened. A general facility may be constructed using a theoretical dose evaluation method because all exterior facilities are blocked, but if the ceiling is open, it is not appropriate to evaluate radiation safety with a simple theoretical calculation method due to the skyshine effect. Therefore, in this study, the radiation safety of the facility was evaluated in the actual field through an ion chamber survey-meter and an accumulated dose-meter called as OSLD, and the actual evaluation environment was modeled and evaluated using the Monte Carlo simulation code as FLUKA. According to the direction of the irradiation, the radiation dose at the facility boundary was difficult to meet the standards set by the regulatory authority, and radiation safety could be secured through additional methods. In addition, it was confirmed that the simulation results using the Iridium-192 source were valid evaluation with the actual measured results.

• Korean Journal of Environmental Agriculture
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• v.40 no.4
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• pp.366-372
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• 2021

BACKGROUND: Ammonia is known as a precursor to fine particulate matter, and according to CAPSS, annual ammonia emissions in the agricultural sector were 249,777 tons as of 2018, accounting for about 79.0% of Korea's total ammonia emissions. In particular, ammonia emissions from agricultural land increased by 19,566 tons (10.2%) compared to the previous year. The Ministry of Environment is setting emission statistics using the ammonia emission coefficient developed in Korea in 2008, but researchers in the agricultural field regard it as a coefficient that does not reflect the reality of Korea's agricultural environment. Accordingly, in order to develop ammonia emission coefficients from the cultivation of apples and pears, Korea's representative fruit type, test agricultural land was set in Iksan, Jeollabuk-do. METHODS AND RESULTS: This study attempted to obtain the ammonia emission coefficient by the treatment of the composite fertilizer (N-P₂O₅-K₂O=12-7-9), and the flux was measured using a dynamic flow-through chamber method. As for the chamber, a total of 12 chambers were installed repeatedly in 4 zones and used to develop emission coefficients. Using compound fertilizers during fruit tree cultivation, the ammonia emission coefficient was evaluated as 10.4 kg NH3/ton for pears and 15.3 kg NH₃/ton for apples. The reason why the ammonia emission coefficient according to the use of composite fertilizers was calculated higher for apple cultivation is believed to be due to the relatively high pH concentration of apple orchard soil. CONCLUSION(S): This study may provide basic data for upgrading the ammonia emission coefficient when using composite fertilizers in agricultural land. In the future, it might be necessary to upgrade the calculation of emissions through the development of ammonia and fine particulate matter emission coefficients considering the agricultural environment of Korea.

• Journal of the Korean Society of Radiology
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• v.16 no.4
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• pp.453-462
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• 2022

In this paper, the artificial intelligence (AI) technology used in the medical image analysis field was analyzed through a literature review. Literature searches were conducted on PubMed, ResearchGate, Google and Cochrane Review using the key word. Through literature search, 114 abstracts were searched, and 98 abstracts were reviewed, excluding 16 duplicates. In the reviewed literature, AI is applied in classification, localization, disease detection, disease segmentation, and fit degree of registration images. In machine learning (ML), prior feature extraction and inputting the extracted feature values into the neural network have disappeared. Instead, it appears that the neural network is changing to a deep learning (DL) method with multiple hidden layers. The reason is thought to be that feature extraction is processed in the DL process due to the increase in the amount of memory of the computer, the improvement of the calculation speed, and the construction of big data. In order to apply the analysis of medical images using AI to medical care, the role of physicians is important. Physicians must be able to interpret and analyze the predictions of AI algorithms. Additional medical education and professional development for existing physicians is needed to understand AI. Also, it seems that a revised curriculum for learners in medical school is needed.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.933-942
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• 2021

The surface image velocimetry was developed to measure river flow velocity safely and effectively in flood season. There are a couple of methods in the surface image velocimetry. Among them the spatio-temporal image velocimetry is in the spotlight, since it can estimate mean velocity for a period of time. For the spatio-temporal image velocimetry analyzes a series of images all at once, it can reduce analyzing time so much. It, however, has a little drawback to find out the main flow direction. If the direction of spatio-temporal image does not coincide to the main flow direction, it may cause singnificant error in velocity. The present study aims to propose a new method to find out the main flow direction by using a fast Fourier transform(FFT) to a spatio-temporal (image) volume, which were constructed by accumulating the river surface images along the time direction. The method consists of two steps; the first step for finding main flow direction in space image and the second step for calculating the velocity magnitude in main flow direction in spatio-temporal image. In the first step a time-accumulated image was made from the spatio-temporal volume along the time direction. We analyzed this time-accumulated image by using FFT and figured out the main flow direction from the transformed image. Then a spatio-temporal image in main flow direction was extracted from the spatio-temporal volume. Once again, the spatio-temporal image was analyzed by FFT and velocity magnitudes were calculated from the transformed image. The proposed method was applied to a series of artificial images for error analysis. It was shown that the proposed method could analyze two-dimensional flow field with fairly good accuracy.