• Korean Journal of Environment and Ecology
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• 제38권2호
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• pp.169-177
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• 2024

This study investigated whether population dynamic analysis based on the height characteristics of Abies nephrolepis was feasible. It was necessary because existing population dynamic analyses based on age and diameter at breast height (DBH) made it difficult to reflect the slow growth characteristics of Abies nephrolepis in harsh environments of high altitudes. The limitations of population dynamics analysis based on the age and DBH distribution of Abies nephrolepis in Seoraksan, Odaesan, and Taebaeksan National Parks, where Abies nephrolepis populations are representative, were verified, and the characteristics of height growth were investigated to comprehensively analyze whether a vertical structure based on height could reveal the population dynamics. The result of this study showed some limitations in understanding the population dynamics of Abies nephrolepis based on age distribution due to practical difficulties in sampling all trees and variations in age distribution within the same community depending on factors such as light conditions. Moreover, it was challenging to differentiate the distribution of DBH classes at fine levels, making it difficult to reflect the rapid growth characteristics of Abies nephrolepis when light conditions become suitable after prolonged stays in smaller DBH classes under shade conditions. However, a comprehensive analysis of the height characteristics of Abies nephrolepis revealed that the density corresponding to the population dynamic characteristics of Abies was high and adequately reflected the predominant tree death at similar height stages, as well as the U-shaped population dynamics at the lower stratum. Moreover, it was possible to identify a transition point in height values under shaded conditions, where the annual growth of Abies nephrolepis individuals in the lower stratum increases significantly, indicating that Abies nephrolepis individuals can escape from competition with other shrubs and undergo vigorous growth only at this height level. Therefore, this study confirmed that a vertical structure based on height can be utilized to understand the population dynamics of Abies nephrolepis in high altitudes, and it is expected that future studies on height characteristics can intuitively reveal the maintenance status of Abies nephrolepis populations in the field.

• Journal of the Korean earth science society
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• 제45권2호
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• pp.157-171
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• 2024

The purposes of this study were: (1) to revalidate the revised Systems Thinking Measuring Instrument (Re_STMI) reported by Lee et al. (2024) among Vietnamese high school students and (2) to investigate the differences in systems thinking abilities between Korean and Vietnamese high school students. To achieve this, data from 234 Vietnamese high school students who responded to translated Re_STMI consisting of 20 items and an Scale consisting of 20 items were used. Validity analysis was conducted through item response analysis (Item Reliability, Item Map, Infit and Outfit MNSQ, DIF between male and female) and exploratory factor analysis (principal axis factor analysis using Promax). Furthermore, structural equation modeling was employed with data from 475 Korean high school students to verify the latent mean analysis. The results were as follows: First, in the item response analysis of the 20 translated Re_STMI items in Vietnamese, the Item Reliability was .97, and the Infit MNSQ ranged from .67 to 1.38. The results from the Item Map and DIF analysis align with previous findings. In the exploratory factor analysis, all items were loaded onto intended sub-factors, with sub-factor reliabilities ranging from .662 to .833 and total reliability at .876. Confirmatory factor analysis for latent mean analysis between Korean and Vietnamese students yielded acceptable model fit indices (χ²/df: 2.830, CFI: .931, TLI: .918, SRMR: .043, RMSEA: .051). Lastly, the latent mean analysis between Korean and Vietnamese students revealed a small effect size in systems analysis, mental models, team learning, and shared vision factors, whereas a medium effect size was observed in personal mastery factors, with Vietnamese high school students showing significantly higher results in systems thinking. This study confirmed the reliability and validity of the Re_STMI items. Furthermore, international comparative studies on systems thinking using Re_STMI translated into Vietnamese, English, and other languages are warranted in the context of students' systems thinking analysis.

• Food Science and Preservation
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• 제30권1호
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• pp.146-154
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• 2023

To develop a multi-functional ingredient, the bioconversion of katsuobushi protein was optimized using Bacillus subtilis HA and Lactobacillus plantarum KS2020. The Dendropanax morbiferus extract (DME) culture with protease activity (102 unit/mL) was prepared by B. subtilis with 2% glucose and 1% skim milk through one day of alkaline fermentation. Katsuobushi protein was effectively hydrolyzed by the DME culture at 60℃ for 3 hours, resulting in a tyrosine content of 156.85 mg%. Subsequently, a second lactic acid fermentation was carried out with 10% monosodium glutamate (MSG) using L. plantarum KS2020 to produce higher levels of GABA. Following co-cultivation for three days, DME exhibited a pH of 8.3 (0% acidity). After seven days, the viable cell count of L. plantarum increased to 9.33 CFU/mL, but viable Bacillus cells were not detected. Taken together, a multi-functional ingredient with enriched GABA, peptides, probiotics, and umami flavor was developed through lactic acid fermentation using hydrolyzed katsuobushi protein. These results indicate that katsuobushi protein could be used as a byproduct to produce a palatable protein hydrolysate using alkaline-fermented DME culture as a proteolytic enzyme source.

• Food Science and Preservation
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• 제30권1호
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• pp.88-97
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• 2023

As livestock consumption in Korea has been gradually increasing, the quality of the final products has been improved to meet this increased demand. In particular, maintaining the water holding capacity (WHC) and minimizing the drip loss during the thawing of frozen meat are of utmost importance. This study investigated the physicochemical properties of frozen pork subjected to thawing under different conditions: at room temperature (20℃, under air), at a low temperature (4℃ refrigerator, under air), under water (20℃, under water in a vacuum bag), under microwave (microwave-thawing, 260 W), and under low-pressure tumbling (20℃, 0.015 bar, tumbling). The shortest thawing time for frozen pork was recorded upon low-pressure tumbling thus indicating a fast heat transfer. The lowest drip loss (0.2%) and highest WHC (94.5%) were also recorded under this condition. A significantly higher drip loss was observed upon microwave- (1.0%) and water-thawing (1.2%), which resulted in the lowest WHC in microwave thawing (87.2%). The highest total count of aerobic bacteria and coliform group were observed upon room temp thawing while the low pressure tumbling and thawing resulted in the lowest aerobic bacteria (1.90 log CFU/g) and coliform (0.78 log CFU/g) count. Consequently, thawing by low pressure tumbling afforded the best food quality.

• Food Science and Preservation
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• 제31권1호
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• pp.149-160
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• 2024

Dextran is a glucose homo-polysaccharide with a predominantly α-1,6 glycosidic linkage of microbial source and is known to be produced primarily by lactic acid bacteria. However, it can also be obtained through the dextran dextrinase of acetic acid bacteria (Gluconobacter oxydans). The dextrin-based dextran was obtained from rice starch using G. oxydans fermentation of rice hydrolysate, and its properties were studied. Both dextrin- and rice hydrolysate-added media maintained the OD value of 6 after 20 h of incubation with acetic acid bacteria, and the gel permeation chromatography (GPC) analysis of the supernatant after 72 h of incubation confirmed that a polymeric material with DP of 480 and 405, which was different from the composition of the substrate in the medium, was produced. The glucose linkage pattern of the polysaccharide was confirmed using the proton nuclear magnetic resonance (¹H-NMR) and the increased α-1,4:α-1,6 bond ratio from 0.23 and 0.13 to 1:2.37 and 1:4.4, respectively, indicating that the main bonds were converted to α-1,6 bonds. The treatment of dextrin with a rat-derived alpha-glucosidase digestive enzyme resulted in a slow release of glucose, suggesting that rice hydrolysate can be converted to dextran using acetic acid bacteria with glycosyltransferase activity to produce high-value bio-materials with slowly digestible properties.

• Food Science and Preservation
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• 제30권5호
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• pp.833-846
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• 2023

Onions are essential vegetables for Koreans' diet and have various physiological activities. However, problems arise every year due to the imbalance between production and demand. Therefore, in this study, nutritional and functional components, and antioxidant activity were analyzed for each growth period in order to utilize onions at the disposal period. Whole onions harvested before June showed higher values of general ingredients, inorganic ingredients, organic acids, spiraeoside, quercetin, total chlorophyll, and antioxidant activity than bulbs harvested in June. On the other hand, the free sugar content was higher in the bulb of the harvest season in June than in whole onions. The total thiosulfinate content was similar to that of whole onions and bulbs in the early stages of growth. In addition, as a result of comparing the flavonoid compound and antioxidant activity of each onion variety, whole onions harvested at 25 weeks were higher in content than onion bulbs harvested in June. In conclusion, onions before the harvest season in June had excellent utilization value as food. Harvesting before 21 weeks is desirable for growing onions with excellent nutritional value, while harvesting after 23 weeks is recommended for excellent functional components and antioxidant activity in onions.

• Food Science and Preservation
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• 제30권6호
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• pp.1095-1106
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• 2023

This study investigated the anti-oxidative and anti-inflammatory effects of Aster glehni (AG) extract in RAW 264.7 cells and Caenorhabditis elegans. The total polyphenol and flavonoid contents were higher in the ethanol extracts than in the hot water extracts. As a result of measuring the moisture contents (%) and extraction yields (%) of AG and drying A. glehni for processing (DAG), 70% ethanol, which has the highest percentage of extraction yield, was selected as the final solvent. DPPH radical scavenging activity showed higher antioxidant activity of ethanol extracts of DAG than AG. The cytotoxicity assay of the AG or DAG ethanol extracts was treated at different concentrations (25, 50, and 100 ㎍/mL), and cell viability rates were higher than 80% at all concentrations. The LPS-stimulated nitric oxide (NO) production in RAW 264.7 was significantly reduced at all concentrations of AG and DAG groups. As a result of measuring the gene expression of iNOS, which induces NO production, the AG or DAG group decreased by 33% and 32%, compared with the phosphate buffer saline (PBS) group. Under inflammatory stress conditions, the survival rate of C. elegans treated with AG or DAG ethanol extract with LPS showed concentration-dependent improvement in survival rate compared with the PBS group. Considering these results, AG could potentially be developed as an antioxidant and anti-inflammatory functional food material.

• Journal of the Korean Society of Radiology
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• 제83권6호
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• pp.1342-1353
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• 2022

Purpose We compared the radiation dose and image quality between the 2nd generation and the 3rd generation dual-source single-energy (DSSE) and dual-source dual-energy (DSDE) CT of the abdomen. Materials and Methods We included patients undergoing follow-up abdominal CT after partial or radical nephrectomy in the first 10 months of 2019 (2nd generation DS CT) and the first 10 months of 2020 (3rd generation DS CT). We divided the 320 patients into 4 groups (A, 2nd generation DSSE CT; B, 2nd generation DSDE CT; C, 3rd generation DSSE CT; and D, 3rd generation DSDE CT) (n = 80 each) matched by sex and body mass index. Radiation dose and image quality (objective and subjective qualities) were compared between the groups. Results The mean size-specific dose estimation of 3rd generation DSDE CT group was significantly lower than that of the 2nd generation DSSE CT (42.5%, p = 0.013) and 2nd generation DSDE CT (46.9%, p = 0.015) groups. Interobserver agreement was excellent for the overall image quality (intraclass correlation coefficient [ICC]: 0.8867) and image artifacts (ICC: 0.9423). Conclusion Our results showed a considerable reduction in the radiation dose while maintaining high image quality with 3rd generation DSDE CT as compared to the 2nd generation DSDE CT and 2nd generation DSSE CT.

• Journal of Korean Society of Disaster and Security
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• 제17권1호
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• pp.9-16
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• 2024

In Korea, as disasters become larger and more complex, there is a trend of shifting from a focus on response and recovery to a focus on prevention and preparedness. In order to prevent and prepare for disasters, each local government manages disaster management resources by stockpiling them. However, although disaster management resources are stored in individual warehouses, they are managed by department rather than by warehouse, resulting in insufficient management of disaster management resources due to the heavy workload of those in charge. In order to intensively manage these disaster management resources, an integrated disaster management resource management center is established and managed at the metropolitan/provincial level. In the case of Gangwon-do, the subject of this study, a warehouse is rented and operated as an integrated disaster management resource management center. When leasing an integrated management center, there is the inconvenience of having to move the location every 1 to 2 years, so it is deemed necessary to build a dedicated facility in an available site. To select a location candidate, network analysis was used to measure access to and use of facilities along interconnected routes of networks such as roads and railways. During network analysis, the Location-Allocation method, which was widely used in the past to determine the location of multiple facilities, was applied. As a result, Hoengseong-gun in Gangwon-do was identified as a suitable candidate site. In addition, if the integrated management center uses our country's logistics system to stockpile disaster management resources, local governments can mobilize disaster management resources in 3 days, and it is said that it takes 3 days to return to normal life after a disaster occurs. Each city's disaster management resource stockpile is 3 days' worth per week, and the integrated management center stores 3 times the maximum of the city's 4-day stockpile.

• Journal of the Korean Society of Radiology
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• 제81권2호
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• pp.365-378
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• 2020

Purpose This study was performed to determine whether the T1 relaxation time of gadoxetic acid-enhanced liver MR imaging is useful for detecting and staging liver fibrosis in patients with chronic liver disease. Materials and Methods One hundred and three patients with suspected focal liver lesion underwent MR imaging and Fibroscan. Fibroscan was chosen as the reference standard for classifying liver fibrosis. T1 relaxation times were acquired before (preT1), 20 minutes after (postT1) contrast administration, and reduction rate of T1 relaxation time (rrT1) on transverse 3D VIBE (volumetric interpolated breath-hold examination) sequence using 3T MR imaging. The optimal cut-off values for the fibrosis staging were determined with ROC analysis. Results PreT1 and postT1 increased and rrT1 decreased constantly with increasing severity of liver fibrosis according to the METAVIR score (F0-F4). There were statistically significant differences between F2 and F3 in preT1 (F2, 836.0 ± 74.7 ms; F3, 888.6 ± 77.5 ms, p < 0.05) and between F3 and F4 in postT1 (F3, 309.0 ± 80.2 ms; F4, 406.6 ± 147.7 ms, p < 0.05) and rrT1 (F3, 65.4 ± 7.7%; F4, 57.3 ± 11.4%, p < 0.05). ROC analysis revealed that combination test (preT1 + postT1) was the best test for predicting liver fibrosis. Conclusion PreT1 and postT1 increased constantly with increasing severity of liver fibrosis. T1 mapping in gadoxetic acid-enhanced liver MR imaging could be a helpful complementary sequence to determine the liver fibrosis stage.