• Journal of Biomedical Engineering Research
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• v.44 no.5
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• pp.336-345
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• 2023

The present study was designed to evaluate changes in neuromuscular properties and the structural and qualitative characteristics of muscles during submaximal isometric contractions at low-to-relatively vigorous target forces and to determine their influence on force steadiness (FS). Thirteen young adult males performed submaximal isometric knee extensions at 10, 20, 50, and 70% of their maximal voluntary isometric contraction using their non-dominant legs. During submaximal contractions, we recorded force, EMG signals from vastus medialis (VM), vastus lateralis (VL), and rectus femoris (RF), and ultrasound images from the distal RF (dRF). Force and EMG standard deviation (SD) and coefficient of variation (CV) values were used to measure FS and EMG steadiness, respectively. Muscle thickness (MT), pennation angle (PA), echo intensity (EI), and texture features were calculated from ultrasound images to assess the structural and qualitative characteristics of the muscle. FS, neuromuscular properties, and texture features showed significant differences across different force levels. Additionally, there were significant differences in EMG_CV among the quadriceps at the 50% and 70% force levels. The results of correlation analysis revealed that FS had a significant relationship with EMG_CV in VM, VL, and RF, as well as with the texture features of dRF. This study's findings demonstrate that EMG steadiness and texture features are influenced by the magnitude of the target force and are closely related to FS, indicating their potential contribution to force output control.

• IMMUNE NETWORK
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• v.22 no.6
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• pp.48.1-48.13
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• 2022

With the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, which are randomly mutated, the dominant strains in regions are changing globally. The development of preclinical animal models is imperative to validate vaccines and therapeutics against SARS-CoV-2 variants. The objective of this study was to develop a non-human primate (NHP) model for SARS-CoV-2 Delta variant infection. Cynomolgus macaques infected with Delta variants showed infectious viruses and viral RNA in the upper (nasal and throat) and lower respiratory (lung) tracts during the acute phase of infection. After 3 days of infection, lesions consistent with diffuse alveolar damage were observed in the lungs. For cellular immune responses, all macaques displayed transient lymphopenia and neutrophilia in the early stages of infection. SARS-CoV-2 Delta variant spike protein-specific IgM, IgG, and IgA levels were significantly increased in the plasma of these animals 14 days after infection. This new NHP Delta variant infection model can be used for comparative analysis of the difference in severity between SARS-CoV-2 variants of concern and may be useful in the efficacy evaluation of vaccines and universal therapeutic drugs for mutations.

• Journal of Korean Society on Water Environment
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• v.40 no.2
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• pp.67-78
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• 2024

The introduction of a significant amount of phosphorous into aquatic environments can lead to eutrophication, which can in turn result in algal blooms. For the effective management of watersheds and the prevention of water quality problems related to nonpoint organic matter (OM) sources, it is essential to pinpoint the predominant OM sources. Several potential OM sources were sampled from upper agricultural watersheds, such as fallen leaves, riparian reeds, riparian plants, paddy soil, field soil, riparian soil, cow manure, and swine manure. Stream samples were collected during two storm events, and the concentrations of dissolved organic carbon (DOC) and phosphorous (DOP) from these OM sources and stream samples were assessed. DOM indicators using fluorescence spectroscopy, including HIX, FI, BIX, and EEM-PARAFAC, were evaluated in terms of their relevance in discerning DOM sources during storm events. Representative DOM descriptors were chosen based on specific criteria, such as value ranges and pronounced differences between low and high-flow periods. Consequently, the spectral slope ratio (S_R) paired with fluorescence index (FI) using end-member mixing analysis (EMMA) proved to be suitable for estimating the contribution of organic carbon (OC). The contribution of each organic phosphorous (OP) in stream samples was determined using the phosphorous-to-carbon (P/C) ratio in conjunction with the OC contribution. Notably, OP derived from swine manure in stream samples was found to make the most dominant contribution, ranging from 61.3% to 94.2% (average 78.1% ± 12.7%). The results of this research offer valuable insights into the selection of suitable indicators to recognize various OM sources and highlight the main sources of OP in forested-agricultural watersheds.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.2
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• pp.41-47
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• 2024

In this study, the resistance characteristics of semi-insulating SiC single crystals grown using the PVT method were investigated, considering the purity level of SiC source powders used in PVT growth and the cooling procedure after crystal growth. Two β-SiC powders with different purities were employed, and the cooling rate after growth was adjusted to achieve various resistance values. 4-inch HPSI-SiC ingots were grown using the PVT method, utilizing SiC powders with low nitrogen concentration and relatively high nitrogen concentration. These ingots were then subjected to different cooling procedures to modify the cooling rate. Transmission/absorption spectra and crystal quality of the grown crystals were analyzed through UV/VIs/NIR spectroscopy and X-ray rocking curve analysis, respectively. Additionally, electrical properties were investigated through non-contact resistivity analysis to identify the dominant factors influencing resistivity properties.

• Composites Research
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• v.37 no.4
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• pp.325-329
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• 2024

To accurately predict airbag deployment during a collision, the mechanical properties of polymer materials at high strain rates according to temperature should be considered. In this study, the mechanical properties of TPO and polypropylene were measured at high strain rates via split-Hopkinson pressure bar tests under various environmental temperatures ranging from -35 to 85℃. Through this, tensile strength and failure strain were derived for each strain rate. As the polymer phase moves toward the high strain rate region, the β-transition becomes dominant, resulting in a non-linear increase in tensile strength in the Eyring plot. Additionally, an airbag module impact simulation was conducted to verify the effects of strain rate on airbag deployment using the LS-DYNA software. It was found that the TPO and polypropylene airbag deployment could be accurately predicted using the strain-rate-dependent mechanical behavior rather than quasi-static properties alone.

• Korean journal of applied entomology
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• v.43 no.4 s.137
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• pp.267-273
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• 2004

To select indicator insects, the abundance of which is one of the major criteria for the evaluation of agricultural environment, was designated and monitored in the three sites (Hongcheon A, B, and Yangpyeong) from 2001 to 2003. Characteristics of rice cultivation are usual cultivation with 2 or 3 times sprayed chemical agents per year in Hongcheon A site, duck cultivation with non-sprayed chemical agent, green manure and mowing in Hongcheon B site, and pond snail with non-sprayed chemical agent, green manure and mowing in Yangpyeong site. Dominant floral species are Digitaria ciliaris (Retz.) Koel., Persicaria thunbergii (Siebold & Zuccarini) H. Gross, Echinochioa crus-galli (L.) Beauvois, and Humulus scandens (Lour.) Merr. in Hongcheon A site, Digitaria ciliaris (Retz.) Koel., Persicaria thunbergii (Siebold & Zuccarini) H. Gross, and Echinochloa crus-galli (L.) Beauvois in Hongcheon B site, and Digitaria ciliaris (Retz.) Koel., Setaria viridis (L.) Beauv., and Persicaria langiseta (De Btuyn) Kitagawa in Yangpyeong site. Degree of green naturality (DGN) was higher in Hongcheon B site (2.0) and Yangpyeong site (3.6) than in Hongcheon A site (1.6). Number of species and individual of insects collected in the three sites were abundant on August and September. The species diversity was higher in Hongcheon B and Yangpyeong than in Hongcheon A. And Coleoptera was dominant in the all sites. The dominance index (DI) was the lowest, but diversify index (H'), evenness index (E) and richness index (RI) were the highest in Hongcheon B site. Based on three results, indicator insects for the evaluation of agricultural environment were selected as Dolichus halensis in Hongeheon A site, as Pheropsophus. javanus and Polionemobius mikado in Hongcheon B and Yangpyeong sites.

• Childhood Kidney Diseases
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• v.12 no.1
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• pp.30-37
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• 2008

Purpose: The present study is an investigation of the progression and prognosis of acute intrinsic renal failure in neonates and children with a diagnosis of acute renal failure or other diseases on admission. Methods: This research is based on a retrospective analysis conducted on 59 patients(male: female=2.2:1) diagnosed with acute intrinsic renal failure between January 2000 and June 2006 at Busan Paik Hospital. The clinical diagnostic criteria of acute renal failure used was serum creatinine <1.2 mg/dL, oliguria with urine output$\leq$0.5 mL/kg/hr and anuria with urine output <50 mL per day. Results: Among those placed under investigation, 7 patients were neonates, 10 patients were 2 months-2 years old, 12 patients were 3-6 years old, 21 patients were 7-12 years old and 9 patients were 13-16 years old. It took 3.1${\pm}$2.8 days on average until the diagnosis was made. The urine output distribution was 21 persons for the oliguria group, and 36 persons for the non-oliguria group, and 2 persons for the anuria group. For the underlying causes, 30 persons were classified in the primary renal disease group, 14 persons in the infection group, 9 persons in the malignancy group, and 6 persons were categorized in another group. As for age distribution, the infected group was predominantly neonates, whereas the dominant age ranges for the primary renal disease and infection categories were 2 months to 2 years old. Also, the primary renal disease was dominant among older children, aged 3 and up. No difference was detected according to seasonal prevalence. However, there was a high morbidity rate among hemolytic uremic syndrome diagnosed in the summer. Peritoneal dialysis was used to treat 4 patients. It took 10.0${\pm}$6.7 days until the patients improved. 18 patients died. The non-oliguria group's mortality rate was lower than other groups. There was a high mortality rate in the neonates and malignancy group. Conclusion: Acute renal failure in childhood seems to take a better clinical course than in adulthood when there is an early diagnosis and proper treatment of underlying diseases.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.678-688
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• 2021

This study was conducted to provide growth characteristics and stand information in preparation for natural regeneration method and silvicultural treatment of seed tree method in Korean red pine stands by using the field inventoried data 18 years after the seed tree regeneration method in 2001 and analyzing the stand and sapling characteristics. The study area was located in the Research Forest of Kangwon National University, Chuncheon-si, Gangwon-do. In November 2018, we collected tree measurement factors, such as diameter at breast height (DBH), height, crown class, stem quality, tree age, and annual height increment on the established plots. We calculated the basal area, volume, height-diameter ratio (HD ratio), and additional stand density variables such as the relative density and %stocking to analyze the managed stands. The number of mother trees was 58 trees/ha, with a 17.7% stocking level, whereas the number of saplings was 2,330 trees/ha, with a 79.0% stocking level. In germination, the age distribution of saplings ranged from 2001 to 2007, with most belonging to 15-16 years. The development condition of saplings was 10 cm in DBH and 8 m in height. DBH and height were higher as the crown class is more dominant, and this difference was statistically significant in the analysis of variance and Duncan's multiple comparison test (p<0.0001). HD ratio ranged mostly between 80% and 90%, and more than 95% of sapling stems were of high quality, with a straight, unbroken top, non-sweep, and non-diseased stem. On average, the annual height increment of saplings was 21.9 cm at 1 year, 43.3 cm at 5 years, 54.3 cm at 10 years, and 64.3 cm at 15 years. The overall height growth with age increased smoothly. According to the analysis of covariance, the annual height growth by crown class differed significantly. The regression analysis parameters revealed that annual height growth increased with age and dominant crown class.

• Korean Journal of Environment and Ecology
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• v.21 no.5
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• pp.400-414
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• 2007

This study has analyzed the vegetation structure to suggest a vegetation ecological restoration model by using the case of the afforestation for erosion control area with Pinus koreaiensis and Betula platyphylla, etc., on the hills of the Young-in mountains after its great fire in 2000. Of the area having a dimension of $1,152,404.3m^2$ selected as a survey site for the existing vegetation, the forest fire area accounted for 69.2% among which, brushwoods accounted the most for 24.67%. As a result of analysis of the 27 surveyed unit plots[unit dimension: $100m^2$] set up in consideration of the existing vegetation pattern and damaged state from the forest fire, the surveyed area was classified into 10 communities. Shrub layer's vegetation was found to be dominant in forest fire areas and the surveyed sites were classified into 5 plant communities, i.e. P. koraiensis community, Quercus variabilis community, P. thunbergii community, Q. serrata community, B. platyphylla community in forest fire areas, while non-forest fire areas were classified into 5 plant communities, such as P. densiflora community, Q. acutissima community, Q. serrata community, Q. mongolica-Q. serrata community, B. platyphylla community. Species diversity of forest fire areas was $0.3679{\sim}0.5907$ and that of non-forest fire areas was $0.5728{\sim}0.8865$. In addition, the number of the species in the forest fire areas was $5{\sim}8$ and that of non-forest areas was $8{\sim}12$; however, the population of forest fire areas$(156{\sim}456)$ was higher than that of non-forest fire areas$(61{\sim}227)$. In the analysis of growth density per layer$[of\;100m^2]$, there appeared $1{\sim}8$ trees of Q. mongolica and $3{\sim}5$ trees of Q. serrata in the upper layer species; $2{\sim}4$ trees of Q. serrata and one tree of Q. mongolica in the canopy layer. As for the characteristics of soil, acidity of forest fire areas was pH 5.45 and that of non-forest fire was pH 5.25. By setting up the middle D.B.H range of Q. mongolica-Q. serrata community as the vegetation restoration model, planting species, planting density and planting models are suggested.

• Clean Technology
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• v.30 no.1
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• pp.37-46
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• 2024

Environmental problems caused by plastic waste have been continuously growing around the world, and plastic waste is increasing even faster after COVID-19. In particular, PP and PE account for more than half of all plastic production, and the amount of waste from these two materials is at a serious level. As a result, researchers are searching for an alternative method to plastic recycling, and plastic pyrolysis is one such alternative. In this paper, a numerical study was conducted on the pyrolysis behavior of non-condensable gas to predict the chemical reaction behavior of the pyrolysis gas. Based on gas products estimated from preceding literature, the behavior of non-condensable gas was analyzed according to temperature and residence time. Numerical analysis showed that as the temperature and residence time increased, the production of H₂ and heavy hydrocarbons increased through the conversion of the non-condensable gas, and at the same time, the CH₄ and C₆H₆ species decreased by participating in the reaction. In addition, analysis of the production rate showed that the decomposition reaction of C₂H₄ was the dominant reaction for H₂ generation. Also, it was found that more H₂ was produced by PE with higher C₂H₄ contents. As a future work, an experiment is needed to confirm how to increase the conversion rate of H₂ and carbon in plastics through the various operating conditions derived from this study's numerical analysis results.