• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.1
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• pp.71-77
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• 2023

With the continuous industrial development, not only natural resource depletion, waste generation, but also various weather conditions are becoming more frequent. Efforts are continuing to recycle industrial by-products to overcome the climate crisis and save resources. Slag is a representative by-product generated in the steel industry, and it is characterized by improving rutting resistance and moisture sensitivity by increasing strength and reducing deformation when used as a material for asphalt concrete. On the other hand, slag has expansion properties so it is used as a relatively low-value-added material such as embankment and refilling materials. In order to expand the application of slag, an experiment was conducted to evaluate the crack resistance of slag asphalt concrete pavement. As a result of the indirect tensile strength test, it was found that the asphalt mixture using slag aggregate showed a value 1.13 times higher than that of the general HMA with the same particle size, and the toughness was 1.17 units, improving crack resistance. In addition, it was found that the failure number of the 4-point beam fatigue experiment and the slag asphalt mixture was 20,409, which was more than doubled compared to the general HMA. Furthermore, Overlay Test showed a tensile load residual rate of 4 times or more, improving crack resistance to repeated fatigue. Accordingly, the use of slag aggregate will likely have various advantages in improving the performance of asphalt concrete pavement.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1C
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• pp.33-42
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• 2006

Lots of river embankments or levees in Korea are quite so old and unknown the origin even. The river deposits, moreover, obtainable easily somewhere were used for materials of embankment without any technical considerations such as the influence soil properties and construction methods on embankment stability. It's natural that safety would be threatened if the water level rises due to flood or rainfall when it comes to abnormal weather conditions, especially. From this point of view, enlargement of embankment, irrigation works, etc. are in progress recently at the situation from a reinforcement work. However, taking influence of soil properties and construction methods on embankment stability into account against cracking or piping is still insufficient. Fragmentary design criteria or irrational construction methods are applied rather as the case may be. In this study, therefore, a way to estimate piping and cracking resistance (Sherard, 1953) has been introduced and reevaluated for practical use with an eye to material properties and its applicability to piping-experienced embankments was examined. Piping possibility was also examined in the present design criteria and compared. In view of the results achieved, it reflects that both yield piping possibility. But it's still necessary to complement how to judge and verify piping resistance of given soils with gradation curves by the representative curve, quantitatively and that piping resistance should consider compaction effects as well.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.101-101
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• 2022

In recent years, due to climate change, the livestock industry has become more interested in the production of forage crops. In Korea, more than 74% of forage crops are cultivated in winter rice fields. In particular, Italian ryegrass (IRG) is depends on imports for more than 70% of its seeds. In generally, the IRG rapeseed cultivation method involves sowing from early October to mid-October by drill sowing seeding or spot seedling. However, the sowing period is delayed due to frequent rainfall during. And, same period require a lot of seeds. However, raising seedlings and transplanted IRG will overcome weather conditions and reduce the amount of seeds. This study was intended to be applied to the domestic IRG seed industry in the future through growth and quantity evaluation according to transplant time and planting density for the production of good quality IRG seeds in rice paddy fields. In this study, transplanting time (October 20, October 30, November 10) and planting density (50, 70, and 80) were cultivated at the National Institute of Crop Science in 2021. The amount of fertilizer applied was adjusted to (N-P₂O₅-K₂O) 4.5-12-12 (kg/10a), and then 2.2(kg/10a) of nitrogen was added each year. For the growth survey, leaf area, canopy coverage, plant length, and seed yield were investigated. Along with the transplanting time, the plant length was higher on October 20 than on October 30 and November 10. On the other hand, leaf area index changes differed depending on the transplanting time and planting density, and were particularly high on October 20, 80 density and 70 density, but similar on October 30 and November 10. 1000 seed weight showed no difference with transplanting time and planting density. On the other hand, the seed yield was 215(kg/10a) for 80 density on October 20, 211(kg/10a) for 70 density, 118(kg/10a) for 50 density, and 80 density for October 30 and November 10. and 70 density did not differ. On the other hand, the 50 density on October 30 and November 10 were 164(kg/10a) and 147(kg/10a) respectively. As can be seen from this study, the earlier the transplant, the higher the seed yield. However, the 50 density was reduced in yield compared to the 70 density and 80 density.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.84-84
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• 2022

The limit of crop cultivation is moving northward due to the temperature rise by climate change. There is a problem with crop growth if early sowing is performed at a time when the temperature is low. It is difficult to secure crop productivity and cultivation stability due to the low temperature and short cultivation period. Therefore, this study was conducted to analyze the change in growth characteristics and yield of corn for grain when early sowing is performed in central region of South Korea. This experiment was conducted at experimental field of Suwon in 2021. Three varieties of corn for grain such as Kwangpyeongok, Sinhwangok, and Hwangdaok were sown at intervals of 5 days from 20 March to 15 April. The planting density at this time was sown with a row interval of 70 cm and a plant interval of 25 cm. Nitrogen, phosphoric acid, and potassium fertilizers were applied at 17.4 kg, 3.0 kg, and 6.9 kg per 10a, respectively. Phosphoric acid and potassium fertilizers were all applied before sowing and nitrogen fertilizer was applied 50% before sowing and 50% in the fifth leaf period. The corn growth characteristics and yield components were investigated. The seedling establishment rate by sowing date was in the range of 68.5~88.5%, and it showed a difference depending on the variety. The range of days from sowing to tassel and silk emergence by sowing date was 79.9~98.4 and 81.0~98.9 days, respectively. As the sowing date was delayed, the days from sowing to tassel and silk emergence decreased. The growth characteristics and yield of corn by sowing date are as follows. Plant height was the highest at 241.3 cm at the sowing on 25 March, and Stalk diameter was the thickest at 25.6 mm at the sowing on 31 March. The fresh weight per plant was the highest at 728 g at the sowing on 25 March, and the dry weight per plant was the highest at 185 g at the sowing on 31 March. Corn growth characteristics did not show a certain trend depending on the sowing date, and corn growth was more vigorous at the sowing on March 25 and 31 than the others. In the case of ear weight, it was the heaviest with 344 g at the sowing on 25 March, and filled ear length ratio showed a tendency to decrease as the sowing time was delayed. The weight of 100 grains and grain yield per 10a of maize were the highest at 36.0g and 878.7kg/10a, respectively at the sowing on 25 March. Although the growth and yield of corn for grain were good during early sowing in the central region of South Korea, it is necessary to investigate the limit temperature for early sowing of corn by examining the annual variation according to weather conditions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.770-778
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• 2023

Sea surface wind is an important variable for elucidating the atmospheric-ocean interactions and predicting the dangerous weather conditions caused by oceans. Accurate sea surface wind data are required for making correct predictions; however, there are limited observational datasets for oceans. Therefore, this study aimed to obtain long-period high-resolution sea surface wind data. First, the ERA5 reanalysis wind field, which can be used for a long period at a high resolution, was regridded and synthesized using the asymmetric typhoon wind field calculated via the Generalized Asymmetric Holland Model of the numerical model named ADvanced CIRCulation model. The accuracy of the asymmetric typhoon synthesized wind field was evaluated using data obtained from Korea Meteorological Administration and Japan Meteorological Administration. As a result of the evaluation, it was found that the asymmetric typhoon synthetic wind field reproduce observations relatively well, compared with ERA5 reanalysis wind field and symmetric typhoon synthetic wind field calculated by the Holland model. The sea surface wind data produced in this study are expected to be useful for obtaining storm surge data and conducting frequency analysis of storm surges and sea surface winds in the future.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.843-856
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• 2023

The global surge in maritime traffic has resulted in an increased number of ship collisions, leading to significant economic, environmental, physical, and human damage. The causes of these maritime accidents are multifaceted, often arising from a combination of crew judgment errors, negligence, complexity of navigation routes, weather conditions, and technical deficiencies in the vessels. Given the intricate nuances and contextual information inherent in each incident, a methodology capable of deeply understanding the semantics and context of sentences is imperative. Accordingly, this study utilized the SentenceBERT model to analyze maritime safety tribunal decisions over the last 20 years in the Busan Sea area, which encapsulated data on ship collision incidents. The analysis revealed important keywords potentially responsible for these incidents. Cluster analysis based on the frequency of specific keyword appearances was conducted and visualized. This information can serve as foundational data for the preemptive identification of accident causes and the development of strategies for collision prevention and response.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.79-85
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• 2023

Skid resistance pavement is an accessory to the road and is a facility for the safe driving of cars by increasing the skid resistance of road pavement. In particular, in bad weather conditions such as snow, rain, and black ice, the skid resistance performance of skid resistance pavement greatly affects the safety of road traffic and drivers. However, BPT(British Pendulum Tester) has a test area of only 0.009 m², making it difficult to represent the overall packaging surface. A reliable method of evaluating slip resistance performance is needed for maintaining non-slip packaging. In this study, the conventional BPT test and the skid resistance performance evaluation method of the PFT(Pavement Friction Tester) and µGT(Micro Grip Tester) tests were compared through guidelines and standard investigations and applied to the field skid resistance performance evaluation. In addition, skid resistance pavement with different skid resistance performance was installed at the test-bed and actual road demonstration sites to compare BPN(British Pendulum Number), SN(Skid Number), GN(Grip Number), and to derive correlations for each performance evaluation method. As a result of the experiment, SN and GN showed similar skid resistance performance, and the GN value was derived similar to BPN × 0.01.

• Journal of Internet of Things and Convergence
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• v.9 no.6
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• pp.93-98
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• 2023

In paddy rice farming, water management is a critical task. To suppress weed emergence during the early stages of growth, fields are deeply flooded, and after transplantation, the water level is reduced to promote rooting and stimulate stem generation. Later, water is drained to prevent the production of sterile tillers. The adequacy of water supply is influenced by various factors such as field location, irrigation channels, soil conditions, and weather, requiring farmers to frequently check water levels and control the ingress and egress of water. This effort increases if the fields are scattered in remote locations. Automated irrigation systems have been considered to reduce labor and improve productivity. However, the net income from rice production in 2022 was about KRW 320,000/10a on average, making it financially unfeasible to implement high-cost devices or construct new infrastructure. This study focused on developing an IoT-Based irrigation valve that can be easily integrated into existing agricultural infrastructure without additional construction. The research was carried out in three main areas: Firstly, an irrigation valve was designed for quick and easy installation on existing agricultural pipes. Secondly, a power circuit was developed to connect a low-power Cat M1 communication modem with an Arduino Nano board for remote operation. Thirdly, a cloud-based platform was used to set up a server and database environment and create a web interface that users can easily access.

• Korean Journal of Remote Sensing
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• v.39 no.5_2
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• pp.785-798
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• 2023

Recently, forest fires have become frequent due to climate change, and the size of forest fires is also increasing. Forest fires in Korea continue to cause more than 100 ha of forest fire damage every year. It was found that 90% of the large-scale wildfires that occurred in Gangwon-do over the past five years were concentrated in the east coast area. The east coast area has a climate vulnerable to forest fires such as dry air and intermediate wind, and forest conditions of coniferous forests. In this regard, studies related to various forest fire analysis, such as predicting the risk of forest fires and calculating the risk of forest fires, are being promoted. There are many studies related to risk analysis for forest areas in consideration of weather and forest-related factors, but studies that have conducted risk analysis for forest-friendly areas are still insufficient. Management of forest adjacent areas is important for the protection of human life and property. Forest-adjacent houses and facilities are greatly threatened by forest fires. Therefore, in this study, a grid-based forest fire-related disaster risk map was created using factors affected by forest-neighboring areas using national branch numbers, and differences in risk ratings were compared for forest areas and areas adjacent to forests based on Gangneung forest fire cases.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.107-117
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• 2024

The objective of this study is to estimate riverbed fluctuations and the volume of aggregate extraction attributable to climate change. Rainfall-runoff modeling, utilizing the SWAT model based on climate change scenarios, as well as long-term riverbed fluctuation modeling, employing the HEC-RAS model, were conducted for the Nonsan River basin. The analysis of rainfall-runoff and sediment transport under the SSP5-8.5 scenario for the early part of the future indicates that differences in annual precipitation may exceed 600 mm, resulting in a corresponding variation in the basin's sediment discharge by more than 30,000 tons per year. Additionally, long-term riverbed fluctuation modeling of the lower reaches of the Nonsan Stream has identified a potential aggregate extraction area. It is estimated that aggregate extraction could be feasible within a 2.455 km stretch upstream, approximately 4.6 to 6.9 km from the confluence with the Geum River. These findings suggest that the risk of climate crises, such as extreme rainfall or droughts, could increase due to abnormal weather conditions, and the increase in variability could affect long-term aggregate extraction. Therefore, it is considered important to take into account the impact of climate change in future long-term aggregate extraction planning and policy formulation.