• Journal of Korea Entertainment Industry Association
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• v.15 no.2
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• pp.149-157
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• 2021

One year has passed since the pandemic of COVID-19, which occurred in Wuhan, China, in November 2019 began. Worldwide, as of January 2021, more than 95 million people have been infected, and the death toll is higher than 2 million. In Korea, there are 74,262 infected and 1,328 dead, and government policies such as social distancing to prevent infection are being implemented. Accordingly, many inconveniences occurred in the physical activity environment, such as the closure of various sports facilities. It was necessary to consider physical activities to maintain healthy life while cooperating with the national policy while preventing infection. This study investigated the benefits of physical activity to reduce the risk of trichomoniasis and diabetes, improve bone mineral density, prolong healthy lifespan, maintain activity performance with aging, and improve psychological anxiety and depression. In addition, the physiological changes that may occur in the situation of stopping exercise due to social distancing to prevent COVID-19 infection were reviewed. In addition, moderate-intensity exercise that helps strengthen immune function by activating natural killer cells, neutrophils, and antibody responses was investigated. In addition, it reduces the level and function of blood B-cells, T-cells, and natural killer cells for several hours, decreases phagocytosis of neutrophils in the nasal cavity, increases inflammatory cytokines, decreases immune function, and increases infection. High-intensity exercise was considered. Therefore, in the age of COVID-19, long-term high-intensity exercise such as marathon, which causes impaired immune function, should be refrained from. And you should do moderate-intensity regular aerobic exercise such as fast walking to help prevent infection. It is also recommended to participate in resistance exercises to prevent loss of muscle mass.

• Korean Journal of Remote Sensing
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• v.38 no.6_3
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• pp.1777-1788
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• 2022

The reservoir is a major water supply source in the domestic agricultural environment, and the monitoring of water storage of reservoirs is important for the utilization and management of agricultural water resource. Remote sensing via satellite imagery can be an effective method for regular monitoring of widely distributed objects such as reservoirs, and in this study, image classification and image segmentation algorithms are applied to Sentinel-1 Synthetic Aperture Radar (SAR) imagery for water body detection in 53 reservoirs in South Korea. Six algorithms are used: Neural Network (NN), Support Vector Machine (SVM), Random Forest (RF), Otsu, Watershed (WS), and Chan-Vese (CV), and the results of water body detection are evaluated with in-situ images taken by drones. The correlations between the in-situ water surface area and detected water surface area from each algorithm are NN 0.9941, SVM 0.9942, RF 0.9940, Otsu 0.9922, WS 0.9709, and CV 0.9736, and the larger the scale of reservoir, the higher the linear correlation was. WS showed low recall due to the undetected water bodies, and NN, SVM, and RF showed low precision due to over-detection. For water body detection through SAR imagery, we found that aquatic plants and artificial structures can be the error factors causing undetection of water body.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.86-94
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• 2022

Replacement of FRP rod as steel reinforcement has been attracted significantly to prevent the degradation of the concrete structure due to corrosion. So, the technology development to extend the structure's service life by improving FRP properties has been proceeded worldwide. Accordingly, it is necessary to develop Korea's CFRP rod and CFRP grid, including the manufacturing techniques to improve the properties of high-strength and high-stiffness. Moreover, the research should be conducted to evaluate the structural behavior of the beams using the CFRP rod or grid. This study investigates the flexural and shear behavior of reinforced concrete beam using demonstrated CFRP rod as reinforcement according to the reinforcement ratio and shear span to depth ratio. From the results, when the reinforcement ratio is out of a specific range, it is seemed that the effect on performance improvement of the beam using CFRP rod is cancelled or not significant. Meanwhile, when the CFRP rod was used as reinforcement, the possibility of shear failure occurred, even steel stirrups were installed in the beam with CFRP rod as tensile reinforcement according to the Korean Design Standard. Therefore, when the CFRP rod is used as tensile reinforcement in a beam, it should be prepared that a specific limitation of reinforcement ratio and an investigation against shear failure. Also, the ductility of the beam using the CFRP rod is determined by the deformation energy evaluation method. So, the ductility should be investigated by applying the deformation energy evaluation method that reflects the structural behavior of the beam.

• Journal of the Korean earth science society
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• v.42 no.2
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• pp.164-174
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• 2021

The study examines the shearing and crushing characteristics of land-derived subaqueous granular materials in a gravel-bed river. A series of large-sized ring shear tests were performed to examine the effect of shear time and shear velocity on the shear stress characteristics of aquarium gravels with a 6-mm mean grain size. Three different shear velocities (i.e., 0.01, 0.1, and 1 mm/sec) were applied to measure the shear stress under the drained (long-term shearing) and undrained (short-term shearing) conditions. Different initial shear velocities, i.e., 0.01→0.1→1 mm/sec and 0.1→0.01→1 mm/sec, were considered in this study. The test results show that the grain crushing effect is significant regardless of drainage conditions. The shear stress of coarse-grained materials is influenced by initial shear velocities, regardless of the drainage conditions. In particular, particle breakage increases as grain size increases. The shearing time and initial shear velocity are the primary influencing factors determining the shear stress of gravels. The granular materials may be broken easily into particles through frictional resistance, such as abrasion, interlocking and fracture due to the particle-particle interaction, resulting in the high mobility of granular materials in a subaqueous environment.

• Journal of Internet Computing and Services
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• v.23 no.1
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• pp.135-145
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• 2022

This paper presented a method to build a predictable smart ammunition logistics system using the 4th industrial technology for ammunition logistics, which is the core functions in the field of defense and logistics. We have analyzed the current level of ammunition logistics with various perspectives such as domestic and overseas logistics policies, technology trends, ammunition logistics characteristics, the smart logistics certification measures by Ministry of Land, Infrastructure and Transport. As a result it is considered that the current ammunition logistics needs needs improvement. To improve this, we presented a direction based on the implications derived after analyzing various ongoing programs such as wired/wireless-based automation, smart ammunition depots, and logistics innovation of the army, navy, and air force that can be applied to the ammunition logistics. In order to implement a data-based smart ammunition logistics management system that can achieve innovation and efficiency of total life cycle while meeting changes in the battlefield environment, we presented 4 objectives such as "automation and modernization of field work", "3D-based storage management & improvement of issuing at war," and "data management for prediction-oriented ammunition management". it is expected that there will be benefits such as improvement of operational continuity, guarantee of ammunition reliability, budget reduction, improvement of inefficiencies such as delay, waiting, and double work, and reduction of accidents.

• Journal of Software Assessment and Valuation
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• v.17 no.2
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• pp.109-116
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• 2021

Traditionally, the engineering field has been dominated by face-to-face education focused on experimental practice, but demand for online learning has soared due to the rapid development of IT technology and Internet communication networks and recent changes in the social environment such as COVID-19. In order for efficient online education to be conducted in the engineering field, where the proportion of experimental practice is relatively high compared to other fields, virtual laboratory practice content that can replace actual experimental practice is very necessary. In this study, we developed a line tracer model and a virtual experimental software to simulate it for efficient online learning of microprocessor applications that are essential not only in the electric and electronic field but also in the overall engineering field where IT convergence takes place. In the developed line tracer model, the user can set various hardware parameter values in the desired form and write the software in assembly language or C language to test the operation on the computer. The developed line tracer virtual experimental software has been used in actual classes to verify its operation, and is expected to be an efficient virtual experimental practice tool in online non-face-to-face classes.

• Journal of the Korean Society for Library and Information Science
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• v.56 no.1
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• pp.253-275
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• 2022

Niklas Luhmann is one of the most contentious and difficult theorist in sociology but follow-up studies on his theory gradually increase for recent 10 years. The purpose of this study is to observe how follow-up studies use the difficult concepts of Luhmann. Unlike previous studies, this study adopted a keyword rather than an article as the unit of analysis because keywords are linguistic constructs that can make concepts observable. The study analyzed co-occurrence of keywords in 139 articles retrieved from social sciences category in Web of Science DB. The key findings were following: the most important keywords were the name of Luhmann(Niklas Luhmann) and theory(social systems); keywords were grouped into 4 clusters(social systems theory, systems theory, legal system and political system, the significant of Luhmann's theory from the viewpoint of the history of social theory); topic terms were systems theory, communication, Autopoiesis, risk, legal system, functional differentiation, environment, social theory, sociological theory, structural coupling, systems and evolution. The significance of the study is following: the study gives keywords as useful access point for beginners of Luhmann's theory; the study proves that content analysis by keywords network can be applied to trend analysis of difficult theoretical researches.

• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.855-863
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• 2022

In this study, the Artificial Neural Network (ANN) was used to mapping air temperature in Seoul. MODerate resolution Imaging Spectroradiomter (MODIS) data was used as auxiliary data for mapping. For the ANN network topology optimizing, scatterplots and statistical analysis were conducted, and input-data was classified and combined that highly correlated data which surface temperature, Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), time (satellite observation time, Day of year), location (latitude, hardness), and data quality (cloudness). When machine learning was conducted only with data with a high correlation with air temperature, the average values of correlation coefficient (r) and Root Mean Squared Error (RMSE) were 0.967 and 2.708℃. In addition, the performance improved as other data were added, and when all data were utilized the average values of r and RMSE were 0.9840 and 1.883℃, which showed the best performance. In the Seoul air temperature map by the ANN model, the air temperature was appropriately calculated for each pixels topographic characteristics, and it will be possible to analyze the air temperature distribution in city-level and national-level by expanding research areas and diversifying satellite data.

• Tunnel and Underground Space
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• v.32 no.5
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• pp.298-311
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• 2022

Some problems, such as aging workers, a decreased population due to a low birth rate, and shortage of skilled workers, are rising in construction sites. Therefore research for smart construction technology that can be improved for productivity, safety, and quality has been recently developed with government support by replacing traditional construction technology with advanced digital technology. In particular, the motor grader that mainly performs road surface flattening is a construction machine that requires the application of automation technology for repetitive construction. It is predicted that the construction period will be shortened if the construction automation technology such as trajectory tracking, automation work, and remote control technology is applied. In this study, we introduce the hardware and software architecture of the smart motor grader to apply unmanned and automation technology and then analyze the traditional earthwork method of the motor grader. We suggested the application plans for the path pattern and blade control method of the smart motor grader based on this. In addition, we verified the performance of waypoint-based path-following depending on scenarios and the blade control's performance through tests.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.3
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• pp.273-281
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• 1990

Two rice varieties, Samkangbyeo and Sangpungbyeo, were transplanted on 1/2000a pots at 6 different dates beginning on May 11 with 10 day interval in 1987 and at 4 different dates beginning on May 21 with 10 day interval in a paddy field at the Chungbuk Provincial Rural Development Administration. Dry matter distributions to stem and leaf sheath, leaves and ear at different growth stages were analyzed to provide basic informations neccessary for the development of dynamic growth model. Dry matter production was reduced as transplanting was delayed and the degree of reduction was greater at the transplanting later than June 1. Dry matter distribution to stem and leaf sheath was increased up to 60-70 days after transplanting with the maximum ratio between 60-70%, which were decreased to 37-43% in pots and 27-33% in field at the end of ripening stage. On the other hand, dry matter distribution to leaf blade was decreased from 40-50% at transplanting to 11-17% at harvesting. Ear dry matter distribution increased rapidly after heading and the distribution ratio was 42-49% in pots and 52-62% in field. Although regression equations to predict dry matter distribution to different parts of rice plant were satisfactory for individual experiment, the application to different experiment was not appropriate.