• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.2
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• pp.116-121
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• 2024

The meats of tuna Thunnus albacares and swordfish Xiphias gladius are ideal for fish patty production, offering high nutrition and other health benefits. Although red fish meat, including tuna, is added for cost-effectiveness, swordfish white meat is also used, as its aroma resembles that of market-sold beef patties. Here, we assessed the different blending ratios of tuna red meat and swordfish white meat (60:40, 40:60, 20:80, and 0:100) to find the optimal combination for fish patty production. Regarding color, the heated fish patties exhibited increased redness (a*) and yellowness (b*) compared with those of non-heated ones, with similar brightness (L*). The heated patties also scored higher concerning hardness, springiness, gumminess, and chewiness. A higher proportion of swordfish white meat resulted in a softer texture, particularly in patties with a ratio of 40% red meat to 60% white meat. Considering the results of the texture comparison analysis, it is recommended that the texture be improved by increasing the physical property "softness." Sensory evaluations revealed that the addition of white meat led to increased scores in terms of smell, beef taste, texture, and elasticity. These results suggest that swordfish white meat, with improved overall quality, is a suitable raw material for fish patties. Accordingly, the recommended ratio of 20% tuna red meat to 80% swordfish white meat is optimal for fish patty production.

• Food Science and Preservation
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• v.30 no.2
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• pp.358-368
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• 2023

Euonymus alatus (Thunb.) Sieb., also known as the arrow tree in Korea, is a plant in East Asia used in traditional medicine and food. In particular, the wings of E. alatus are rich in phenolic compounds. This study evaluated the antioxidant, α-glucosidase inhibition, and anti-cancer activities of E. alatus wing extracts. The radical and hydrogen peroxide scavenging acitvities and reducing the power of 1,000 ㎍/mL E. alatus wing extracts, were similar to those of the positive control (0.1% BHT, 0.1% α-tocopherol). In addition, ethanol and methanol extract at 250 ㎍/mL showed 95.70 and 94.99% of α-glucosidase inhibition activity, respectively. The ethanol extract of E. alatus wings had the highest total polyphenol and flavonoid contents (867.8 mg% and 521.7 mg%, respectively). The E. alatus wing extracts significantly decreased the cell viability of LNCaP human prostate cancer cells (p<0.001), MDA-MB-231 human breast cancer cells (p<0.001), and HT-29 human colon cancer cells (p<0.001) in a dose-dependent manner. However, there was no significant effect on B16 mouse melanoma cells. Notably, the ethanol extracts showed higher cancer cell growth inhibitory activity in LNCaP and HT-29 cells than the other extracts. These results suggest that E. alatus wing extracts could have significant clinical applications, and our results can be used as basic data for future functional food material development.

• Journal of the Korean Applied Science and Technology
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• v.40 no.4
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• pp.856-867
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• 2023

Due to the increase in fine dust caused by environmental pollution, oxidative damage and aging of the skin are accelerated. In this study, the antioxidant, hyaluronic acid, filaggrin, MMP-1, and ROS level of selected herbal extracts were evaluated to confirm the protective efficacy of keratinocytes treated PM10. As a result, the antioxidant capacity of 1,1-diphenyl-2-picrylhydrazyl(DPPH), 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid(ABTS), and FRAP assay increased in a concentration-dependent manner. Keratinocytes the group treated with 300 ㎍/ml of PM10, hyaluronic acid and filaggrin decreased by more than 50%, and increased in the group treated with extracts of Alpinia officinarum, Ulmus macrocarpa, and Ulmus macrocarpa but decreased when the extract was treated, which is evaluated as inhibiting the degradation of collagen and elastin. In addition, in the case of ROS measurement using zebrafish embryos, it was confirmed that the extract was reduced when the extract was treated 25 ㎍/ml, the intensity of fluorescence similar to the negative control was shown, confirming that the production of ROS was significantly reduced. Through this study, the selected oriental medicinal materials, Alpinia officinarum, Ulmus macrocarpa, and Ulmus macrocarpa, protect the skin from fine dust. It is thought that it can be used as an anti-aging product for skin improvement as a material that can be improved or improved.

• Journal of Forest and Environmental Science
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• v.40 no.2
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• pp.90-98
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• 2024

This study analyzes the characteristics of sound-absorbing materials made from forest by-products of the deciduous tree species Zelkova serrata (Z. serrata) by evaluating their sound absorption performance. Accordingly, sound-absorbing materials with varying sample thicknesses, leaf sizes, and drying conditions were fabricated. The sound absorption properties were measured using the impedance tube method via middle-type measurement tube (100 Hz-3,200 Hz). The sound absorption properties were evaluated using the average sound absorption coefficient (ASAC), which was calculated from the measured sound absorption coefficients at 250 Hz, 500 Hz, 1,000 Hz, and 2,000 Hz. The ASAC value significantly improved as the leaf size increased to 0.5×0.5 cm², 1.0×1.0 cm², and 2.0×2.0 cm². The ASAC values under the two drying conditions were similar. There was no significant difference in ASAC according to the leaf size under the air-dried leaf condition, with a thickness of 2.50 cm. The highest ASAC value according to the sound-absorbing material thickness was 0.47 at a thickness of 2.50 cm and leaf size of 2.0×2.0 cm² under the air-dried leaf condition. In addition, the variation in ASAC was 0.23, indicating that the sound absorption performance according to leaf thickness was more significant than the difference in absorption properties according to leaf size. A sound absorption coefficient (SAC) of 0.4 or higher was observed across the measurable frequency band (100 Hz-3,200 Hz). Furthermore, the SAC values with respect to leaf size and thickness were close to 1 in the high-frequency range above 2,000 Hz. Therefore, it is considered that sound-absorbing materials using Z. serrata leaves are advantageous in the field of absorbing noise in a high-frequency band of 2,000 Hz or more, and it is better to manufacture a thickness of 2.50 and 2.0×2.0 cm².

• Steel and Composite Structures
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• v.50 no.6
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• pp.705-720
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• 2024

Analyzing the collapse behavior of thin-walled steel structures holds significant importance in ensuring their safety and longevity. Geometric imperfections present on the surface of metal materials can diminish both the durability and mechanical integrity of steel shells. These imperfections, encompassing local geometric irregularities and deformations such as holes, cavities, notches, and cracks localized in specific regions of the shell surface, play a pivotal role in the assessment. They can induce stress concentration within the structure, thereby influencing its susceptibility to buckling. The intricate relationship between the buckling behavior of these structures and such imperfections is multifaceted, contingent upon a variety of factors. The buckling analysis of thin-walled steel shell structures, similar to other steel structures, commonly involves the determination of crucial material properties, including elastic modulus, shear modulus, tensile strength, and fracture toughness. An established method involves the emulation of distributed geometric imperfections, utilizing real test specimen data as a basis. This approach allows for the accurate representation and assessment of the diversity and distribution of imperfections encountered in real-world scenarios. Utilizing defect data obtained from actual test samples enhances the model's realism and applicability. The sizes and configurations of these defects are employed as inputs in the modeling process, aiding in the prediction of structural behavior. It's worth noting that there is a dearth of experimental studies addressing the influence of geometric defects on the buckling behavior of cylindrical steel shells. In this particular study, samples featuring geometric imperfections were subjected to experimental buckling tests. These same samples were also modeled using Finite Element Analysis (FEM), with results corroborating the experimental findings. Furthermore, the initial geometrical imperfections were measured using digital image correlation (DIC) techniques. In this way, the response of the test specimens can be estimated accurately by applying the initial imperfections to FE models. After validation of the test results with FEA, a numerical parametric study was conducted to develop more generalized design recommendations for the stainless-steel shell structures with the initial geometric imperfection. While the load-carrying capacity of samples with perfect surfaces was up to 140 kN, the load-carrying capacity of samples with 4 mm defects was around 130 kN. Likewise, while the load carrying capacity of samples with 10 mm defects was around 125 kN, the load carrying capacity of samples with 14 mm defects was measured around 120 kN.

• Journal of the Korean Association of Geographic Information Studies
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• v.27 no.1
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• pp.41-51
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• 2024

If an underground accident occurs, the cause must be quickly identified and human and material damage reduced. The Underground Accident Investigation Committee is responsible for identifying the causes of accidents and preparing response plans to prevent similar accidents from occurring in the future. The law stipulates that the Underground Accident Investigation Committee can operate from a minimum of 6 months to a maximum of 9 months after an accident occurs. However, the operation schedule of the Underground Accident Investigation Committee seems difficult to cite the accident investigation report to the construction project currently in progress at the same time project. In this study, the Underground Accident Investigation Committee seeks to establish a strategy for developing technology that can shorten data collection and analysis, which previously took 3 months, to less than 1 month. As a result of the research, five areas of technology development identified, ground data collection and transmission technology, ground safety data generation technology, digital twin-based underground safety analysis and visualization technology, digital twin-based geo-ambulance construction and operation technology, and digital twin-based geo-ambulance standardization and legal system. research was able to be conducted. If the proposed technology is developed, it is expected to contribute to reducing accident scenes through faster decision making than before.

• Resources Recycling
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• v.33 no.3
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• pp.30-37
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• 2024

In this study, we investigated the separability of vanadium and tungsten from spent SCR (Selective Catalytic Reduction) catalyst leach solution by reduction of vanadium and solvent extraction using Alamine 336 and conducted experiments to optimize process conditions. It is difficult to separate vanadium and tungsten due to their similar chemical behavior, but tungsten can be selectively extracted from acidic solution when vanadium extraction is prevented by reducing anionic pentavalent vanadium to cationic tetravalent vanadium. The results showed that NaHSO₃ was most suitable as a reducing agent, and the extraction efficiency of vanadium decreased and the separation efficiency increased as the amount of reducing agent added, reaction time, and temperature increased. When reducing NaHSO₃ 1.5 eq, 60 min, and 60℃, which are optimal conditions of reduction, vanadium and tungsten were effectively separated with vanadium extraction efficiency of 5.8%, tungsten extraction efficiency of 99%, and separation factor of vanadium and tungsten of 7,564.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.185-196
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• 2006

Fracture toughness is a material property for crack initiation and propagation in fracture mechanics. For mode I fracture toughness measurement in concrete, RILEM committees 89-FMT proposed three-point bend tests based on the two-parameter fracture model. But, there is no proposed test method as a standard for mixed mode test for now. And RILEM three-point bend test procedure is complicate. Therefore, in this study, brazilian disks of various size were designed as the concrete with a similar specified concrete strength and maximum size of coarse aggregate($G_{max}$) were respectively 20mm and 40mm. And mode I fracture toughness of brazilian disks was compared with that of RILEM three-point bend test. As a result, it was suggested appropriate size(thickness, diameter) and notch length ratio of brazilan disk on the $G_{max}$. And it was verified that stress intensity factors for mixed mode can be easily calculated with the disk specimen. Stress intensity factors of a concrete brazilian disk were evaluated with finite element analysis and five terms approximation for comparison.

• Korean Journal of Environment and Ecology
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• v.38 no.4
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• pp.405-415
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• 2024

The bioacoustics generated in urban parks contribute to the overall sound diversity of a city, creating a harmonious acoustic environment and maintaining the balance of the soundscape. However, due to the rapid urbanization process, the acoustic environment in urban parks is continuously deteriorating due to increased noise. In this study, we present an approach to monitoring the acoustic environment of urban parks by analyzing the soundscape of Namsan Urban Natural Park in Seoul. Acoustic data were collected continuously for one month from August 2021 in four facility districts of the study site using autonomous recording units, and a total of 2,784 hours of sound material were obtained. We also compared soundscape characteristics over time in each district using acoustic indices (ACI, ADI, BI, NDSI) representing soundscape complexity, acoustic diversity, degree of bioacoustics, and anthropogenic disturbance. The results showed that acoustic indices related to bioacoustics varied between districts, but most indices showed similar variation patterns due to the influence of anthropogenic sounds. In particular, regional differences closed during periods of high bird activity but not during periods of high human activity. We suggest that considering both acoustic characteristics and multiple acoustic indices is necessary for managing the soundscape of urban parks. The results of this study are expected to provide essential data for assessing the health of urban ecosystems based on soundscapes and to be used for monitoring the acoustic environment of urban parks.

• Tunnel and Underground Space
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• v.34 no.5
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• pp.554-570
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• 2024

In this study, a field test was conducted to determine the effect of reinforcement around the insert on the wear damage of the pickcutter. Prior to the field test, a linear cutting test was conducted on the reinforced pickcutter and unreinforced pickcutter to determine the effect of the pickcutter reinforcement on the cutter force, and the capacity of the roadheader was checked based on the results. The cutter force analysis showed that the average normal force and cutting force were similar regardless of the reinforcement, but the maximum normal force and cutting force showed a large standard deviation depending on the reinforcement. From the torque review, it was determined that a depth of penetration of 6 mm or less using the average cutting force and 4 mm or less using the maximum cutting force was appropriate. In the wear damage analysis, the number of used pickcutters, the number of pickcutters with inserts retained, the number of cases of uneven wear, and the difference in weight between before and after use showed that the reinforced pickcutters outperformed the unreinforced pickers by 16% to 28%. From these results, we can conclude that pickcutter reinforcement has a significant impact on the durability of the pickcutter. However, the cost of reinforcing pickcutters is higher than that of unreinforced pickcutters due to material costs and additional processes, so it is necessary to consider the effect of performance improvement and cost.