• Journal of Platform Technology
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• v.11 no.6
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• pp.56-67
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• 2023

The increased demand for electronic components, spurred by the Fourth Industrial Revolution and the COVID-19 pandemic, has facilitated human life but also escalated the production of e-waste. Discussions on the impact of e-waste have primarily revolved around environmental, health, and social issues, with global legislations focusing on addressing these concerns. However, e-waste poses unique security risks, such as potential technological and personal information leaks, unlike conventional waste. Current discourse on e-waste security is notably insufficient. This study aims to empirically analyze the relatively overlooked trends in e-waste security, employing three methodologies. Firstly, it assesses the general trend in discussions on e-waste by analyzing year-wise documents and media reports. Secondly, it identifies key trends in e-waste security by examining documents on the subject. Thirdly, the study reviews national security guidelines related to e-waste disposal to assess the necessity of designing security strategies for e-waste management. This research is significant as it is one of the first in korea to address e-waste from a security perspective and offers a multi-dimensional analysis of e-waste security trends. The findings are expected to enhance domestic awareness of e-waste and its security issues, providing an opportunity for proactive response to these security risks.

• Journal of the Institute of Convergence Signal Processing
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• v.25 no.2
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• pp.94-99
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• 2024

Recently, wind power has been gaining attention as a highly efficient renewable energy source, leading to various technological developments worldwide. Typically, wind power is operated in the form of large wind farms with many wind turbines installed in areas rich in wind resources. However, in developing countries or regions isolated from the power grid, off-grid small wind power systems are emerging as an efficient solution. To efficiently operate and expand off-grid small-scale power systems, the development of real-time monitoring systems is required. For the efficient operation of small wind power systems, it is essential to develop real-time monitoring systems that can actively respond to excessive wind speeds and various environmental factors, as well as ensure the stable supply of produced power to small areas or facilities through an Energy Storage System (ESS). The implemented system monitors turbine RPM, power generation, brake operation, and more to create an optimal operating environment. The developed small wind power system can be utilized in remote road lighting, marine leisure facilities, mobile communication base stations, and other applications, contributing to the development of the RE100 industry ecosystem.

• Journal of Bio-Environment Control
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• v.33 no.2
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• pp.120-128
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• 2024

Since ChatGPT was released in 2022, the generative artificial intelligence (AI) industry has seen massive growth and is expected to bring significant innovations to cognitive tasks. AI-based image generation, in particular, is leading major changes in the digital world. This study investigates the technical foundations of Midjourney, Stable Diffusion, and Firefly-three notable AI image generation tools-and compares their effectiveness by examining the images they produce. The results show that these AI tools can generate realistic images of tomatoes, strawberries, paprikas, and cucumbers, typical crops grown in greenhouse. Especially, Firefly stood out for its ability to produce very realistic images of greenhouse-grown crops. However, all tools struggled to fully capture the environmental context of greenhouses where these crops grow. The process of refining prompts and using reference images has proven effective in accurately generating images of strawberry fruits and their cultivation systems. In the case of generating cucumber images, the AI tools produced images very close to real ones, with no significant differences found in their evaluation scores. This study demonstrates how AI-based image generation technology can be applied in agriculture, suggesting a bright future for its use in this field.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.5
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• pp.683-694
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• 2024

Flood control capacity enhancement measures in watersheds can be broadly categorized into structural and non-structural approaches. In this study, we propose the improvement of the flood control capacity in the Seomjin River basin through non-structural measures by optimizing the operation of the Seomjin River Dam, specifically by introducing a flexible flood season restricted water level (FSRWL). The flexible operation of FSRWL involves setting lower restricted water levels at the beginning of the flood season to increase flood control capacity and gradually raising them as the season progresses to manage flood control more effectively. As a structural measure, we examined the installation of riverside storage areas, a representative technique of nature-based solutions (NbS). Using the 2020 flood event as a case study, we analyzed the flood level reduction effects of implementing structural and non-structural measures both separately and simultaneously to identify the most effective and economical approach. The results indicate that the optimal flood prevention strategy for the main stream of the Seomjin River during the 2020 flood event involves operating the Seomjin River Dam FSRWL at EL. 190 m during the mid-flood season as a non-structural measure and installing a riverside storage area downstream of Godalgyo Bridge in Daepyeong-ri, Gokseong-gun as a structural measure.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.5
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• pp.673-681
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• 2024

The purpose of this study was to estimate the flood flow and the range of inundation in the downstream area of the Aprokgang(Riv.) that occurred in 2024 using satellite images. The study area was the Aprokgang(Riv.) watershed, the longest river in North Korea. Satellite image Sentinel-1A(SAR-C) data was used for flood analysis before and after the flood. As a result of the analysis of the inundation range using satellite images, it was confirmed that there was a change in the water surface before and after the flood. However, the image after the flood was taken six days after the peak discharge of the flood, so there are limitations in extracting the accurate extent of the flooding. As a result of the analysis using satellite precipitation and ground observed rainfall, the rainfall exceeded 500-year rainfall amount, and the peak-flow was simulated as 85,102 m³/s. As a result of analyzing the inundation range by using the contour lines from AW3D30, it was determined that the inundation occurred around the 15 m contour line. In the future, it is need to conduct a study that can extract more scientifically the inundation range through the use of the inundation analysis model.

• Ecology and Resilient Infrastructure
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• v.11 no.3
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• pp.78-89
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• 2024

Estuarine provides unique environmental conditions in terms of salinity concentration and sediment change patterns as freshwater and seawater mix. These conditions allow it to possess biodiversity that cannot be found in other ecosystems. This study was conducted to investigate and analyze distribution characteristics and biota of vegetation in the Gonyangcheon Estuarine Wetland, a brackish area, to prepare basic data for the conservation and sustainable use of estuarine wetlands. The vegetation in the Gonyangcheon Estuarine Wetland was classified into 23 plant communities across a total of six physiognomic vegetation types, including lentic herbaceous vegetation, lotic herbaceous vegetation, salt marsh vegetation, segetal vegetation, and substitutional vegetation. In particular, the Zoysia sinica community was widely distributed in the lower reaches, showing typical characteristics of tidal wetland and increasing its conservation value. From a biodiversity perspective, a total of 1,067 species were identified (an increase of 53 species compared to 2012) and 15 species of endangered wildlife were identified. Gonyangcheon Estuarine Wetland is an open estuary with excellent ecological connectivity. Various topography and landscapes such as rice paddies, forests, and salt marshes were organically developed and distributed, playing a positive role in promoting biodiversity, including brackish water organisms. Therefore, systematic conservation of the Gonyangcheon Estuarine Wetland will contribute to protecting migration routes of organisms and promoting ecological stability by securing a wetland ecological axis connected to the coast.

• Journal of Wetlands Research
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• v.25 no.1
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• pp.35-47
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• 2023

Korean facility horticulture and hydroponic cultivation methods increase, requiring the management of waste water generated. In this study, the amount of fertilizer contained in the discharged waste liquid was determined. By evaluating this as a price, it was suggested to reduce water treatment costs and recycle fertilizer components. It was evaluated based on the results of major water quality analysis of waste liquid by crop, such as tomatoes, paprika, cucumbers, and strawberries, and in the case of P component, it was analyzed by converting it to the amount of phosphoric acid (P₂O₅). The amount of nitrogen (N) can be calculated by discharging 1,145.90kg·ha^-1 of tomatoes, 920.43kg·ha^-1 of paprika, 804.16kg·ha^-1 of cucumbers, 405.83kg·ha^-1 of strawberries, and the fertilizer content of P₂O₅ is 830.65kg·ha^-1 of paprika, 622.32kg·ha^-1 of tomatoes, 477.67kg·ha^-1 of cucumbers. In addition, trace elements such as potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), and manganese (Mn) were also analyzed to be emitted. The price per kg of each item calculated by averaging the price of fertilizer sold on the market can be evaluated as KRW, N 860.7, P 2,378.2, K 2,121.7, Ca 981.2, Mg 1,036.3, Fe 126,076.9, Mn 62,322.1, Zn 15,825.0, Cu 31,362.0, B 4,238.0, Mo 149,041.7. The annual fertilizer loss amount for each crop was calculated by comprehensively considering the price per kg calculated based on the market price of fertilizer, the concentration of waste by crop analyzed earlier, and the average annual emission of hydroponic cultivation. As a result of the analysis, the average of the four hydroponic crops was 5,475,361.1 won in fertilizer ingredients, with tomatoes valued at 6,995,622.3 won, paprika valued at 7,384,923.8 won, cucumbers valued at 5,091,607.9 won, and strawberries valued at 2,429,290.6 won. It was expected that if hydroponic drainage is managed through self-treatment or threshing before discharge rather than by leaking it into a river and treating it as a pollutant, it can be a valuable reusable fertilizer ingredient along with reducing water treatment costs.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.148-153
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• 2010

This study was carried out to investigate the effect of extraction methods on the physicochemical characteristics using seed oil of wild green tea (Camellia sinensis). When the solvent extraction method after grinding and steam treatment (SGS) was used for oil extraction, the yield was highest. The specific gravity was a range of $0.91{\sim}0.94g/cm^{3}$ irrespective of extraction methods of oil. However, the light in the solvent extraction method after grinding (SG), the red in the pressure extraction method after grinding and roasting treatment (PGR), and the yellow in SG method were highest. Among various fatty acids, the concentrations of C16 : 0, C18 : 1 and C18 : 2 were highest, irrespective of extraction methods. Especially, the C16 : 0 concentration was in the order of SG (34.78%), SGS (23.04%), and PRGS method (23.01%), the C18 : 1 concentration was in the order of PGR (43.35%), SGS (42.7%), SG method (39.0%), and in the case of C18 : 2, it was in order of PGR (23.15%), SGS (23.03%), and SG method (15.01%). The saturated fatty acid concentration was in the order of SG (40.59%), PGR (31.61%), and SGS method (30.1%). On the other hand, in the case of the unsaturated fatty acid, it was in the order of SGS (69.9%), PGR (68.39%), and SG method (59.41%). The acid values in the SGS and SG method after 10 days of storage were in the range of 6~8 mgKOH/g. However, in the case of PGR method, it was increased with the increase of storage time and was 49.3 mgKOH/g after 60 days. The peroxide values in the SGS and SG method were in the range of 60~100 mEq/g from 10 to 60 days of storage. On the other hand, when the storage time was increased from 10 to 30 days, it was sharply increased from 60 to 240 mEq/g. The rancidity was in the order of $Fe^{2+}$, $Cu^{2+}$, $Cr^{2+}$, $Zn^{2+}$ and $Ni^{2+}$, irrespective of extraction methods. Especially, when butylated hydroxyanisole (BHA) was added into oil containing 1.0 ppm of <$Fe^{2+}$, the peroxide value was decreased from 539.4 to 216.6%. These results show that seed oil of Camellia sinensis grown in Iksan can be applied as sources for cosmetics, detergents, food, and pharmaceuticals.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.515-527
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• 2014

This study conducted experiment for understanding engineering characteristics of domestic sands by examining standard sand and sand from Yokji Island and Nakdong River in terms of confining pressure, $K_0$, over consolidation and relative density factors through triaxial compression test. The test showed that deviator stress by strain positively changed as confining pressure and relative density grow while $K_0$ and over consolidation factors do not directly correlated with it. Angle of internal friction decreases as confining pressure increases which strengthens contact force between particles, and declines as relative density drops, whereas $K_0$ and over consolidation factors hardly affect the results. When it comes to volumetric strain, volume expansion decreases as confining pressure increase due to crushability and rearrangement of particles while $K_0$ and over consolidation shows same movement unconditionally, and relative density appears compressed as it grows at the beginning however it expands as axial strain increases. Modulus of elasticity ($E_{sec}$) by strain has tendency into convergence resulting in initial secant modulus of elasticity ($E_{ini}$) > secant modulus of elasticity($E_{sec}$) > tangent modulus of elasticity ($E_{tan}$). On the other hand, it grows as confining pressure and relative density increase while indicating similar modulus of elasticity ($E_{sec}$) regarding on $K_0$ and over consolidation. Slope of critical line (M) tended to decrease as confining pressure increases, follow same line according to $K_0$, confining pressure and relative density, and increase as relative density grows.

• Journal of Wetlands Research
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• v.17 no.3
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• pp.264-272
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• 2015

Understanding bird status is essential for the systematic and sustainable management of the Nakdong River Estuary, taking into consideration the relationship between ecosystems and the bird species. In this study, bird status in the Nakdong River Estuary Bird Sanctuary prior to the Four Major Rivers Project was analyzed using the bird monitoring data (2003-2011) from surveys conducted by the Busan Development Institute. The high percentage of winter visitors in terms of both species diversity (38.36%) and individual bird numbers (63.14%) suggest that the Nakdong River Estuary is an important wintering site for migratory birds. Cumulative numbers of individual birds were higher in Myungji (208,601), West Nakdong River (202,444), Eulsukdo (153,232), and Baekhap Doyodeung (150,595). The total numbers of migratory species were higher in Eulsukdo (171), Ilungdo (124), Myungji (132), and Samrak (121). Among the 232 species found in the Nakdong River Estuary, Anas platyrhynchos (17.71%) was the most common species, followed by Anas poecilorhyncha (8.85%), Larus crassirostris (6.48%), Anser fabalis (6.09%), Anas penelope (5.16%), and Calidris alpina (4.22%). Most bird taxa, except shelducks, showed annual fluctuations in individual numbers, with increasing frequency during survey periods. Of these, cormorants, swans, and gulls showed higher fluctuations than other taxa. Swans decreased drastically in numbers in 2007-2008 and 2009-2010 compared to previous years. Shore birds, gulls, wagtails, and other forest birds were also less common in 2010-2011. These results suggest that there were some environmental changes that might have affected the birds in the Nakdong River Estuary. Overall, the results suggest that habitat types affect the distribution of dominant species.