• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.200-210
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• 2007

Phytoplankton community was investigated in Asan Bay, South Korea. Samples were collected at 5 stations along Asan Bay axis during wet season from June to August, 2006. In June and July, salinity decreased especially at inside stations. Nutrients were high in June and July, however, decreased in August. We observed the community of phytoplankton including diatoms(62.8%), dinoflagellates(17.3%), cryptophytes(14.8%), euglenophytes(1.0%), cyanophytes (0.9%), chlorophytes(0.4%), and some of unidentified taxa(2.8%) during summer 2006 in Asan Bay. In June, dinoflagellates (mainly Prorocentrum sp.(29.6%)) were dominated, accounting for about 43.5% of total cell number, whereas in July and August diatoms (mainly Leptocylindrus sp.(21.4%), Chaetoceros sp.(27.6%)) were dominated occupying 69.1% and 89.9%, respectively. The results suggest that freshwater inputs affected phytoplankton community in the Asan Bay ecosystem.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.211-218
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• 2007

In this study, we investigated the spatial distribution of macrozoobenthos in the estuarine sandy flat, the Bongam tidal flat located in Masan Bay during March, 2004. A total 13 species were identified at 12 stations within the tidal flat. The mean density was $20,267\;ind./m^2$, and mean biomass was $228.1g/m^2$. Dominant species in the Bongam tidal flat were all polychaetes: Prionospio japonicus ($11,716\;ind./m^2$, 57.8%) and Polydora ligni ($3,929\;ind./m^2$, 19.4%) of spionoid polychaete, and Neanthes succinea ($3,425\;ind./m^2$, 16.9%) of nereid polychaete. The most dominant species, P. japonicus distributed evenly all stations in the tidal flat. But N. succinea showed high density at the upper area of the tidal flat. Species diversity index (H') was in the range of 0.6 to 1.2 which is relatively low due to the prominent of P. japonicus and few species richness at each station. The study area was divided into two station groups (group A and B) based on the cluster analysis and MDS ordination, and the spatial distribution of macrozoobenthos on the Bongam tidal flat seemed to be in the influence of exposure duration from tidal levels and specific geological topography.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.2
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• pp.77-84
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• 2024

In the fourth industrial-revolution era, the construction industry is transitioning from traditional methods to digital processes. This shift has been challenging owing to the industry's employment of diverse processes and extensive human resources, leading to a gradual adoption of digital technologies through trial and error. One critical area of focus is the safety management at construction sites, which is undergoing significant research and efforts towards digitization and automation. Despite these initiatives, recent statistics indicate a persistent occurrence of accidents and fatalities in construction sites. To address this issue, this study utilizes large-scale language-model artificial intelligence to analyze big data from a construction safety-management information network. The findings are integrated into on-site models, which incorporate real-time updates from detailed design models and are enriched with location information and spatial characteristics, for enhanced safety management. This research aims to develop a big-data-driven safety-management platform to bolster facility and worker safety by digitizing construction-site safety data. This platform can help prevent construction accidents and provide effective education for safety practices.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.23 no.2
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• pp.69-78
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• 2024

Recently, the use of CCTV to prevent crowd accidents has been promoted, but research is needed to compensate for the spatial limitations of CCTV. In this study, pedestrian density was measured using drone footage, and based on a review of existing literature, a threshold of 6.7 people/m² was selected as the cutoff risk level for crowd accidents. In addition, we conducted a preliminary study to determine drone parameters and found that the pedestrian recognition rate was high at a drone altitude of 20 meters and an angle of 60°. Based on a previous study, we selected a target area with a high concentration of pedestrians and measured pedestrian density, which was found to be 0.27~0.30 per m². The study shows it is possible to measure risk levels by determining pedestrian densities in target areas using drone images. We believe drone surveillance will be utilized for crowd safety management in the near future.

• Journal of Korea Water Resources Association
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• v.57 no.4
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• pp.301-310
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• 2024

The spatial and temporal non-uniform distribution of precipitation makes water management difficult. Due to climate change, nonuniform distribution of precipitation is worsening, and droughts and floods are occurring frequently. Additionally, the intensity of droughts and floods is intensifying, making existing water management systems difficult. From June 2022 to June 2023, most of the water storage rates of major dams in the Yeongsan river and Seomjin river basin were below 30%. In the case of Juam dam, which is the most dependent on water use in the basin, the water storage rate fell to 20.3%, the lowest ever. Pyeongnim dam recorded the lowest water storage rate of 27.3% on May 4, 2023. Due to a lack of precipitation starting in the spring of 2022, Pyeongnim dam was placed at a drought concern level on June 19, 2022, and entered the severe drought level on August 21. Pyeongrim dam and Suyangje(dam) have different operating institutions. Nevertheless, the low water level was not reached at Pyeongnim dam through organic linkage operation in a drought situation. Pyeongnim dam was able to stably supply water to 63,000 people in three counties. In order to maximize the use of limited water resources, we must review ways to move water smoothly between basins and water sources, and prepare for water shortages caused by climate change by establishing a consumer-centered water supply system.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.1
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• pp.17-24
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• 2024

In this paper, we propose a highly secure technique to hide confidential data in image pixels using a quadruple encryption techniques. In the proposed technique, the boundary surface where the image outline exists and the flat surface with little change in pixel values are investigated. At the boundary of the image, in order to preserve the characteristics of the boundary, one bit of confidential data that has been multiply encrypted is spatially encrypted again in the LSB of the pixel located at the boundary to hide the confidential data. At the boundary of an image, in order to preserve the characteristics of the boundary, one bit of confidential data that is multiplely encrypted is hidden in the LSB of the pixel located at the boundary by spatially encrypting it. In pixels that are not on the border of the image but on a flat surface with little change in pixel value, 2-bit confidential data that is multiply encrypted is hidden in the lower 2 bits of the pixel using location-based encryption and spatial encryption techniques. When applying the proposed technique to hide confidential data, the image quality of the stego-image is up to 49.64dB, and the amount of confidential data hidden increases by up to 92.2% compared to the existing LSB method. Without an encryption key, the encrypted confidential data hidden in the stego-image cannot be extracted, and even if extracted, it cannot be decrypted, so the security of the confidential data hidden in the stego-image is maintained very strongly. The proposed technique can be effectively used to hide copyright information in general commercial images such as webtoons that do not require the use of reversible data hiding techniques.

• Land and Housing Review
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• v.15 no.1
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• pp.77-97
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• 2024

This study aims to examine the distinctions in evaluation index items between overseas and domestic ecological area-related systems, derive analytical indicators, and assess recently completed apartment complexes before and after the implementation of overall ecological area ratios. The objective is to analyse variances in the application of ecological area characteristics, categorizing them into ecological area analysis indicators and presenting their implications. The spatial scope covers completed apartment complexes in both metropolitan and non-metropolitan areas. Thirty-six completed apartment complexes were selected for analysis, and basic ecological area data were compiled. Subsequently, the data was utilized to categorize three analysis indicators-ecological area ratio, ecological area diversity, and ecological area connectivity-by metropolitan and non-metropolitan areas, as well as by type of apartment complex (sale housing versus rental housing) and size (large-scale, medium-scale, and small-scale). Results of the analysis indicate higher ecological area ratios and greater diversity in ecological area spatial types in metropolitan areas compared to non-metropolitan areas, and in pre-sale housing complexes compared to rental housing complexes. Mediumand large-scale apartment complexes exhibit higher ecological area ratios, with ecological area diversity being more pronounced. Ecological area connectivity reveals more numerous and varied connection points and types in metropolitan areas than in non-metropolitan areas. Implications of this study suggest that large-scale development should prioritize securing ecological area ratios and diversity in apartment complexes. Enhancing biodiversity necessitates establishing connections within and beyond the ecological area network of the complex. Future research should focus on linking the ecological area network within the complex.

• The Journal of the Acoustical Society of Korea
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• v.27 no.4
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• pp.163-170
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• 2008

Most of receiving rooms for the measurement of floor impact sound have rectangular shapes with couple of meters of dimension, with reflective finishing, no furniture, no curtains. Modal overlaps in those condition are the major reason for the low reproducibility, and as a matter of course, the low credibility. It is the major purpose of this study that searching for a better measurement method which mitigate the effect of modal overlap on measurement. Two ways of methods are tested. One is the way described in ISO standards which enables controlling the room modes of receiving rooms, the other is the way which enables to get more precise spatial averages in receiving rooms with room modes. It is not easy maintaining the reverberation time of low frequency bands in the range between 1s and 2s, though it is proven to be effective controlling the room modes with base traps. Space-time average SPL's through combinations of rotating microphones are easy to measure, and have good consistencies with average SPL of entire receiving room.

• Journal of Industrial Convergence
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• v.22 no.1
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• pp.1-20
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• 2024

Regarding the discourse on the correlation between governmental financial support and firm performance, much emphasis has been placed on the role of individual corporate characteristics as well as spatial features. However, there is a notable scarcity of empirical research examining the integrated impact of corporate and cluster characteristics on managerial performance. This study addresses this gap by empirically analyzing the financial and non-financial outcomes resulting from specific allocations of governmental financial support. Additionally, it explores corporate and cluster characteristics predicted to moderate the influence between governmental financial support and firm performance. The analysis employs a two-level hierarchical linear model (HLM) at individual and group levels. The data, reorganized based on business registration numbers at the firm and cluster levels, ultimately utilized panel data from 83,395 firms and 641 clusters. The research findings indicate that governmental financial support demonstrates a positive effect (+) on both sales and patents for firms, suggesting its effectiveness in complementing market failures. Results from the hierarchical linear model analysis show that when combined with human capital capacity, absorptive capacity, and cluster network density, governmental financial support exhibits significant positive effects on sales. This study contributes theoretical and practical insights by analyzing the relationship between governmental financial support and firm performance using a two-level hierarchical linear model. It highlights the role of corporate characteristics such as human capital and absorptive capacity, along with cluster characteristics like cluster network density, in moderating the effects of governmental financial support on firm performance.

• Korean Journal of Agricultural and Forest Meteorology
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• v.26 no.1
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• pp.75-88
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• 2024

It would be advantageous to predict acreage and yield of crops in major grain-exporting countries, which would improve decisions on policy making and grain trade in Korea. A climate suitability model can be used to assess crop acreage and yield in a region where the availability of observation data is limited for the use of process-based crop models. The objective of this study was to determine the climate suitability index of wheat by province in Ukraine, which would allow for the spatial assessment of acreage and yield for the given crop. In the present study, the official data of wheat acreage and yield were collected from the State Statistics Service of Ukraine. The EarthStat data, which is a data product derived from satellite data and official crop reports, were also gathered for the comparison with the map of climate suitability index. The Fuzzy Union model was used to create the climate suitability maps under the historical climate conditions for the period from 1970 to 2000. These maps were compared against actual acreage and yield by province. It was found that the EarthStat data for acreage and yield of wheat differed from the corresponding official data in several provinces. On the other hand, the climate suitability index obtained using the Fuzzy Union model explained the variation in acreage and yield at a reasonable degree. For example, the correlation coefficient between the climate suitability index and yield was 0.647. Our results suggested that the climate suitability index could be used to indicate the spatial distribution of acreage and yield within a region of interest.