• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1135-1144
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• 2023

In this paper, bending strength and permeability tests were conducted on concrete permeable blocks manufactured by recycling industrial by-products of oyster shell and blast furnace slag to measure and compare bending strength and permeability coefficient, and present experimental research results. To this end, a total of 54 specimens with a size of 200x200x60mm for surface layer and base layer were manufactured, and bending strength and permeability test were carried ourt accoridng to KS F 4419. Eighteen types of mixing designs were implemented by varying the mixing and replacement rates of oyster shells and blast furnace slag. As a result of the experiment, the higher the mixing ratio of oyster shell, the lower the bending strength and the permeability coefficient. Thereafter, a total of three permeable blocks with dimensions of 200x200x60mm were manufactured and subjected to bending strength and permeability tests according to KS F 4419. As a result of the test, the bending strength satisfies the standard of KS F 4419, and the permeability coefficient is 12 times higher than the standard of KS F 4419. It seems that the proper mixing of oyster shells and blast furnace slag increases the amount of air, and further research on durability and economic feasibility of materials used to manufacture permeable blocks is required.

• Journal of the Korean Society of Radiology
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• v.83 no.6
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• pp.1229-1239
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• 2022

Recently, artificial intelligence (AI) technology has shown potential clinical utility in a wide range of MRI fields. In particular, AI models for improving the efficiency of the image acquisition process and the quality of reconstructed images are being actively developed by the MR research community. AI is expected to further reduce acquisition times in various MRI protocols used in clinical practice when compared to current parallel imaging techniques. Additionally, AI can help with tasks such as planning, parameter optimization, artifact reduction, and quality assessment. Furthermore, AI is being actively applied to automate MR image analysis such as image registration, segmentation, and object detection. For this reason, it is important to consider the effects of protocols or devices in MR image analysis. In this review article, we briefly introduced issues related to AI application of MR image acquisition and reconstruction.

• Journal of Korea Water Resources Association
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• v.57 no.7
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• pp.451-460
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• 2024

It is necessary to apply a rational urban flood simulation method to analyze the causes of frequent urban flooding and to develop appropriate countermeasures. Previous studies in Korea have performed flood simulations by inputting the results of manhole overflow from sewer systems and river overflow into two-dimensional flood flow simulation models. It, however, is reasonable to simulate flooding from river and manhole overflows in a complex manner. In this study, we used the 1D-2D coupling functionality of the TUFLOW module, which is a part of XP-SWMM, to simulate the compound flooding of rivers and urban areas. That method was applied to the lower basin of the Naengcheon River in Pohang City, Gyeongsangbuk-do, where both inland flooding and river overflow coincided due to Typhoon Hinnamnor on September 5 and 6, 2022, to verify its applicability.

• Archives of Craniofacial Surgery
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• v.25 no.4
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• pp.171-178
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• 2024

Background: We developed a novel interlocking three-dimensional (3D) miniplate design with an adjustable configuration. As this device is new, surgeons must become familiar with its application. This study evaluated the usability and learning curves associated with the novel interlocking 3D miniplate for mandibular fracture fixation. Methods: The study participants, nine plastic surgeons, were asked to apply an interlocking 3D miniplate and a standard miniplate to polyurethane mandible models. The participants had completed the Basic Craniomaxillofacial Osteosynthesis course during residency and had operated on craniomaxillofacial fractures within the past 5 years. They were instructed to place the interlocking 3D miniplate three times and the standard miniplate once. We assessed the time required for implant placement, the comfort level of the surgeons, and the biomechanical stability of the plates. Biomechanical testing was conducted by subjecting the mandible to forces ranging from 10 to 90 N and the displacement was measured. Results: The results indicate increasing comfort with each attempt at placing the interlocking 3D miniplate, with a significant difference between the first and third attempts. Additionally, a reduction in application time was noted with repeated attempts, suggesting improved efficiency. Biomechanical tests showed comparable stability between the tested plates. Conclusion: Multiple attempts at applying the interlocking 3D miniplate resulted in increased comfort and reduced application time. These findings indicate that, despite its novelty, the interlocking 3D miniplate is relatively straightforward to apply and has a short learning curve. However, surgeons must have specific qualifications to ensure proper training and minimize errors during placement.

• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.5
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• pp.41-50
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• 2024

An increasing pattern of extreme rainfall recently affected the rural infrastructures with catastrophic damage, especially the overtopping of a fill dam embankment in the Republic of Korea. The overtopping was caused by the sudden increase in reservoir water level over the dam crest level, and it was not easy work to predict a priori because of its non-linear behavior. Fuzzy time series (FTS) is a fuzzy-logic inference procedure and is suited to apply to non-linear prediction methods such as machine learning. This study used the Wangshin reservoir and Goesan-dam cases, which experienced overtopping in 2023 and 2022, respectively. Wangshin Reservoir was a typical agricultural fill dam and needed to stack more available data, with only the daily storage rate (water level) of 7 years, starting on 2 May 2016. Therefore, we used Goesan-dam data to select appropriate variables and compare the analysis result, which was stacked with about 17 years of records. The analyses adapted LSTM to compare with FTS. As a result, the reservoir water level was applied to predict the overtopping water level, and it was shown that the FTS method could predict the actual water levels effectively according to the result of comparison with LSTM. Then, the FTS method was expected to predict reservoir water level a priori to make appropriate countermeasures on overtopping events as one of the alternatives.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.279-288
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• 2016

Stable Isotope Analysis(SIA) of carbon and nitrogen is useful tool for the understanding functional roles of target organisms in biological interactions in the food web. Recently, mixing model based on SIA is frequently used to determine which of the potential food sources predominantly assimilated by consumers, however, application of model is often limited and difficult for non-expert users of software. In the present study, we suggest easy manual of R software and package SIAR with example data regarding selective feeding of crustaceans dominated freshwater zooplankton community. We collected SIA data from the experimental mesocosms set up at the littoral area of eutrophic Chodae Reservoir, and analyzed the dominant crustacean species main food sources among small sized particulate organic matters (POM, <$50{\mu}m$), large sized POM (>$50{\mu}m$), and attached POM using mixing model. From the results obtained by SIAR model, Daphnia galeata and Ostracoda mainly consumed small sized POM while Simocephalus vetulus consumed both small and large sized POM simultaneously. Copepods collected from the reservoir showed no preferences on various food items, but in the mesocosm tanks, main food sources for the copepods was attached POM rather than planktonic preys including rotifers. The results have suggested that their roles as grazers in food web of eutrophicated reservoirs are different, and S. vetulus is more efficient grazer on wide range of food items such as large colony of phytoplankton and cyanobacteria during water bloom period.

• The Journal of Engineering Geology
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• v.18 no.1
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• pp.55-68
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• 2008

At present underground structures such as road tunnels, railway tunnels, underground petroleum storages and radioactive waste storages are being constructed in numerous places in Korea. For the construction of underground structrues, it should be accounted for natural factors (geology, hydrogeology, soil, vegetation, topography and drainage patterns) and human-social factors (land use, urbanization, population, culture and transportation). Especially, hydrogeology should be regarded as an important factor for evaluating the safety of underground structures and their impact to groundwater system around the structures. This study aimed to recognize hydrogeological characteristics of shallow formations in the area from Dongrae crossway to Seo-Dong where 45 boreholes were drilled for the construction of Line-3 subway in Busan Megacity. Slug tests for unsaturated and saturated zones were conducted on 30 boreholes in the study area. From the result of the slug tests, it was identified that average zonal hydraulic conductivity in the unsaturated zone was higher than that in the saturated zone. Besides, the slug test result in the saturated zones may reflect hydraulic properties of the upper most part of the saturated zones.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.5
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• pp.480-496
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• 2017

CMAQ (Community Multiscale Air Quality)-HDDM (High-order Direct Decoupled Method) simulations with MICS-Asia 2010 and INTEX-B 2006 emissions inventories were performed to investigate the impact of Chinese $NO_x$ and VOC emissions on 1-hr ozone concentrations over South Korea during May to July in 2014. Chinese $NO_x$ and VOC emissions in MICS-Asia 2010 were 60% higher and 100% lower than those in INTEX-B 2006 during the simulation period. It makes the ratio of Chinese VOC to $NO_x$ emissions in INTEX-B 2006 (Case 1) is 3.2 times higher than that in MICS-Asia 2010 (Case 2). When the observed period mean 1-hr ozone concentration averaged across 106 air monitoring sites in the SMA (Seoul Metropolitan Area) was 37.6 ppb, the modeled values were similar to each other; 37.3 ppb for Case 1, and 40.4 ppb for Case 2. Both cases show that daily maximum 1-hr ZOC (Zero-Out Contribution) of Chinese $NO_x$ and VOC emissions were as high as 55 ppb and 35 ppb for the episode respectively. Correlation coefficients between ZOC of Chinese $NO_x$ and VOC emissions and the SMA daily maximum 1-hr ozone were 0.49~0.69. It indicates that Chinese emissions occasionally affect the SMA daily ozone peaks. On the other hand, Case 2 predicted 7 ppb and 1 ppb higher ZOC of Chinese $NO_x$ and VOC emissions than Case 1, when simulated ozone in the SMA is over 80 ppb. It implies that upwind $NO_x$ emissions would be more important than upwind VOC emissions for the long-range transport of ozone in Northeast Asia.

• Journal of Microbiology and Biotechnology
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• v.26 no.11
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• pp.1951-1964
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• 2016

1,4-Dioxane-degrading bacterial consortia were enriched from forest soil (FS) and activated sludge (AS) using a defined medium containing 1,4-dioxane as the sole carbon source. These two enrichments cultures appeared to have inducible tetrahydrofuran/dioxane and propane degradation enzymes. According to qPCR results on the 16S rRNA and soluble di-iron monooxygenase genes, the relative abundances of 1,4-dioxane-degrading bacteria to total bacteria in FS and AS were 29.4% and 57.8%, respectively. For FS, the cell growth yields (Y), maximum specific degradation rate ($V_{max}$), and half-saturation concentration ($K_m$) were 0.58 mg-protein/mg-dioxane, $0.037mg-dioxane/mg-protein{\cdot}h$, and 93.9 mg/l, respectively. For AS, Y, $V_{max}$, and $K_m$ were 0.34 mg-protein/mg-dioxane, $0.078mg-dioxane/mg-protein{\cdot}h$, and 181.3 mg/l, respectively. These kinetics data of FS and AS were similar to previously reported values. Based on bacterial community analysis on 16S rRNA gene sequences of the two enrichment cultures, the FS consortium was identified to contain 38.3% of Mycobacterium and 10.6% of Afipia, similar to previously reported literature. Meanwhile, 49.5% of the AS consortium belonged to the candidate division TM7, which has never been reported to be involved in 1,4-dioxane biodegradation. However, recent studies suggested that TM7 bacteria were associated with degradation of non-biodegradable and hazardous materials. Therefore, our results showed that previously unknown 1,4-dioxane-degrading bacteria might play an important role in enriched AS. Although the metabolic capability and ecophysiological significance of the predominant TM7 bacteria in AS enrichment culture remain unclear, our data reveal hidden characteristics of the TM7 phylum and provide a perspective for studying this previously uncultured phylotype.

• Journal of Korean Society of Forest Science
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• v.99 no.4
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• pp.597-602
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• 2010

The most basic matter to establish forest carbon circulation village is statistic on greenhouse gas emissions. But currently, although there is statistic on greenhouse gas emissions in the level of city or province, there is not statistic on greenhouse gas emission in village unit. According to the results, The model area is located in Seobyeok-ri, Chunyang-myeon, Bonghwa-gun, Gyeongsangbuk-do, the total $CO_2$emissions caused by energy used in the model area was $1,755tCO_2$. Heating accounts for 55% of total emissions followed by 23% for power and 22% for vehicles. The model area emitted $572tCO_2$ due to rice growing and livestock raising, accounting for approximately 24.5% of total $CO_2$ emissions. It is expected that a reduction of as much as $884tCO_2$ emissions will be made from the current $964tCO_2$ to a level of 1/12th that amount, or $80tCO_2$ by replacing heating energy currently used in the model area with wood bioenergy such as wood chips or pellets. In addition, carbon emission reduction is expected for both heating and power by replacing the power consumption in houses, buildings, and street lights with solar power.