• Journal of the Korean Society for Heat Treatment
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• v.32 no.5
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• pp.201-211
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• 2019

Low carbon steel (S20C steel) and SPCC steel sheet have been austenitic nitrided at $700^{\circ}C$ in a closed pit type furnace by changing the flow rate of ammonia gas and heat treating time. When the flow rate of ammonia gas was low, the concentration of residual ammonia appeared low and the hardness value of transformed surface layer was high. The depth of the surface layer, however, was shallow. With increasing the concentration of residual ammonia by raising up the ammonia gas flow, both the depth of the surface layer and the pore depth increased, while the maximum hardness of the surface layer decreased. By introducing a large amount of ammonia gas in a short time, a deep surface layer with minimal pores on the outermost surface was obtained. In this experiment, while maintaining 10~12% of residual ammonia, the flow rate of inlet ammonia gas, 7 liter/min, was introduced at $700^{\circ}C$ for 1 hour. In this condition, the thickness of the surface layer without pores appeared about $60{\mu}m$ in S20C steel and $30{\mu}m$ in SPCC steel plate. Injecting additional methane gas (carburizing gas) to this condition played a deteriorating effect due to promoting the formation of vertical pores in the surface layer. For $1^{st}$ transformed surface layer for S20C steel, maintaining 10~12% residual ammonia condition via austenitic nitriding process resulted in ${\varepsilon}$ phase with relatively high nitrogen concentration (just below 4.23 wt.%N) among the mixed phases of ${\varepsilon}+{\gamma}$. The ${\varepsilon}$ phase was formed a specific orientation perpendicular to the surface. For $2^{nd}$ transformed layer for S20C steel, ${\gamma}$ phase was rather dominant (just above 2.63 wt.%N). For SPCC steel sheet, there appeared three phases, ${\gamma}$, ${\alpha}(M)$ and weak ${\varepsilon}$ phase. The nitrogen concentration would be approximately 2.6 wt.% in these phases condition.

• Korean Journal of Clinical Laboratory Science
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• v.53 no.1
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• pp.81-87
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• 2021

The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide. T2DM is one of the most common types of diabetes and is caused by increased insulin resistance and reduced insulin secretion. Peroxisome proliferator-activated receptor γ coactivator 1 alpha (PPARGC1A) is a master modulator of mitochondrial biogenesis and of gluconeogenesis in liver. In this study, we analyzed genetic polymorphisms of PPARGC1A gene in a middle-aged Korean population with T2DM. Using the genotype data of 736 T2DM cases and 4544 healthy controls obtained from the Korean Association Resource (KARE), we analyzed genetic correlations between single nucleotide polymorphisms (SNPs) of PPARGC1A and T2DM. Fifteen SNPs of PPARGC1A demonstrated a statistically significant association with T2DM. Of these, rs10212638 exhibited the strongest correlation with T2DM (P-value=0.015, OR=1.29, CI=1.05~1.59), and the minor G allele of PPARGC1A increased the risk of T2DM. This is the first study to report a significant association between genetic polymorphisms in PPARGC1A and T2DM and suggests that SNPs of PPARGC1A display genetic correlations to the etiology of T2DM.

• Korean Journal of Food Science and Technology
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• v.54 no.2
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• pp.155-162
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• 2022

This study investigated the immunostimulatory effect of enzymatic porcine placental hydrolyzate (EPPH) in cyclophosphamide (Cy)-treated rats. This effect of EPPH prevented Cy-induced decreases in body, spleen, and thymus weights and natural killer (NK) cell activity. The numbers of immune cells, such as white blood cells, granulocytes, and lymphocytes, and mid-range absolute counts were significantly higher compared to the control group. The levels of tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, IL-2, IL-12, and immunoglobulin G (IgG) were notably reduced by Cy, while EPPH prevented these effects. Histopathological analysis of spleen samples revealed the protective effect of EPPH against Cy-induced immunosuppression. The findings demonstrate that EPPH can alleviate immunosuppression by cell viability, tissue damage, and regulation of the levels of cytokines. EPPH may have value as a component of immunostimulatory agents or an ingredient in functional foods.

• The Korea Journal of Herbology
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• v.29 no.2
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• pp.39-45
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• 2014

Objectives : The purpose of this study was to investigate antiaging and antioxidant effects on cultured human skin fibroblast with 80% ethanol extracts of plants including of stem of Dendropanax morbifera, Corni fructus and Lycii Fructus. Methods : An ethanol extract of three medicinal plants including stem of Dendropanax morbifera, Corni fructus and Lycii Fructus. Extracts were assessed to determine the mechanism of antioxidant and antiaging activities. Antioxidant activity of extract was evaluated by two different assays as 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and super oxide dismutase (SOD) like activities. These extracts were tested for cell viability on HS68 skin fibroblast by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. We investigated the effects of Ultraviolet-B irradiation on cytotoxicity, type 1 collagen, elastin level and oxidative damage in cultured human skin fibroblast (HS68). Recently, many studies have reported that elastin is also involved in inhibiting or repairing wrinkle formation, although collagen is a major factor in the skin wrinkle formation. Results : The extracts obtained dose-dependently increased the scavenging activity on DPPH radical scavenging activity and SOD like activity. The extracts of complex herbal medicine showed low cytotoxicity as more than 100% cell viability in 100ppm/ml concentration. HS68 fibroblasts were survived 70% at 120 $mJ/cm^2$ UVB irradiation and treated tumor necrosis factor (TNF)-alpha. The levels of aging factors and cytotoxicity were decreased by ethanol extract of complex herbal medicine. Conclusions : These results suggest that ethanol extracts of complex medicinal plants of including of stem of Dendropanax morbifera, Corni fructus and Lycii Fructus may have value as the potential antioxidant and antiaging medicinal plant.

• Journal of Wetlands Research
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• v.24 no.2
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• pp.69-82
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• 2022

In this study, we investigated the bacterial community structure in organic rice-fish mixed farming paddy soil by using high-throughput sequencing technology. The results showed that compared with the organic rice cultivated soil, the content of AP (available phosphorus) increased by 310.23 % and the content of OM (organic matter) increased by 168.83%. The most abundant phyla in paddy soils were Proteobacteria, Bacteriodetes, and Chloroflexi, whose relative abundance was above 47.83%. Among the dominant genera, the relative abundance of Limisphaera in paddy soils was observed. Alpha diversity indicated that the bacterial diversity of paddy soils was similar among each other. The bacterial community structure was affected by the relative abundance of bacteria, not the species of bacteria. Principal Coordinated Analysis (PCoA) results showed that the bacterial communities in organic rice-fish mixed farming soil and organic paddy soil were correlated to each other; the bacterial community structure was distinctively grouped by four different systems (paddy soil under organic rice-fish mixed farming system, organic rice cultivation, and conventional rice cultivation), where the first two are closely related to each other than the third one. The results provide basal support for organic agri-cultivation while improving an ecological value at the same time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.638-646
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• 2023

Recently, active research has been conducted to enhance the power characteristics and thermal stability of lithium-ion batteries (LiBs) by modifying separators using a ceramic coating method. However, since the thermal properties and surface features of the separator vary depending on the characteristics of the ceramic powders applied to the separator, it is crucial to manufacture ceramic powders optimized for the separator's performance. In this study, we evaluated the characteristics of three types of α-alumina (A-1, A-2, and A-3) produced with varying dispersant contents and milling times, in addition to commercial α-alumina (AES-11). Subsequently, the optimized powders (A-3) were coated onto the separator using an aqueous binder for comparison with the characteristics of an AES-11 coated separator and an uncoated PE separator. The A-3 coated separator improved electrolyte wettability with a low contact angle (44.69°) and increased puncture strength (538 gf). Furthermore, it exhibited excellent thermal stability, with a shrinkage value of 5.64% when exposed to 140℃ for 1 hour, compared to the AES11 coated separator (6.09%) and the bare PE separator (69.64%).

• Journal of fish pathology
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• v.36 no.2
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• pp.277-286
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• 2023

Korean rockfish, Sebastes schlegelii, is a representative bony fish that belongs to the family Scorpaenidae and the order Scorpaeniformes. It has high ecological and economic value and is widely cultivated in many East Asian countries, including South Korea, Japan and China. One of streptococci, Streptococcus iniae, is Gram-positive cocci with a negative reaction for catalase and oxidase. The Korean rockfish shows clinical signs when infected with S. iniae, such as body darkening, bleeding, enlarged kidneys, blurred eyes, abdominal distension, etc., ultimately leading to death. The Korean rockfish causes significant economic losses every year in South Korea due to streptococcosis. In this study, we identified bacteria from the fish using polymerase chain reaction and conducted analyses of hemolytic activity and biochemical tests using API 20 STREP and API ZYM systems. Results of confirming the hemolytic activity (n=4) observed in alpha-type hemolysis (25%), beta-type hemol- ysis (50%), and gamma-type hemolysis (25%) of isolates. The biochemical test results exhibited sig- nificant variation among S. iniae. Additionally, we performed intraperitoneal injection with S. iniae in the fish and analyzed the phylogenetic tree using housekeeping genes of S. iniae, including cpsD, arcC, glnA, groEL, gyrB, mutS, pheT, prkC, rpoB, and tkt, via multilocus sequence typing (MLST). The lethal dose (LD₅₀) showed strong pathogenicity, such as 3.34 × 10 colony-forming unit (CFU)/ml for 23FBStr0601 strain and 7.16 × 10 CFU/ml for 23FBStr0602 strain. 23FBStr0603 strain showed relatively low pathogenicity at 1.73 × 10⁵ CFU/ml. The strains 23FBStr0601 and 23FBStr0602, which showed strong pathogenicity, clustered into one monophyletic group. The 23FBStr0603 strain showed weak pathogenicity and formed a monophyletic group with KCTC 3657.

• Korean Journal of Medicinal Crop Science
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• v.11 no.3
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• pp.236-245
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• 2003

The study was performed for elucidating angiotensin converting enzyme (ACE) inhibitory activity and comparing antioxidative activity of Panax ginseng extracts prepared at different conditions. Total phenolic content, inhibitory activity on ACE and antioxidative effects were tested on 10 ethanolic extracts and correlation coefficient between total phenolic content and physiological activity was calculated. Yield and total phenolic content of 50% ethanolic extract prepared at $85^{\circ}C$ exhibited the highest value as 42.52% and 0.82%, respectively. Among the fractions obtained from 50% ethanolic extract prepared at room temperature, water fraction showed the highest value in yield as 72.08% and ethyl acetate fraction did in total phenolic content as 6.59%. In the test on ACE inhibitory activity, 50% ethanolic extract obtained at room temperature indicated the strongest effect of 93.8% which was higher than 85.2% of commercialized ACE inhibitor and solvent fractions showed potent inhibitory activity in order of hexane fraction, diethyl ether fraction, ethyl acetate fraction, butanol fraction and water fraction at concentration of $4000{\mu}g/ml$. 50% Ethanolic extract prepared at $85^{\circ}C$ had the most potent inhibition effect on human LDL oxidation as 78.2% at $200{\mu}g/ml$ and the other extracts also did above 60%. Diethyl ether fraction and ethyl acetate fraction showed strong inhibition activity $(34.38%{\sim}78.13%)$ on LDL oxidation at concentration of $10{\sim}200\;{\mu}g/ml$. From the statistical analysis via SAS program, correlation coefficient between total phenolic content and ACE inhibitory effect was 0.6353 at P<0.05. Conclusively, this report showed that the most efficient extraction condition for elevating inhibitory activity on ACE and LDL oxidation, phenolic content and yield from Panax ginseng was 50% ethanol extraction at room temperature or high temperature condition. And Panax ginseng would be used for preventing hypertension or atheroscrelosis for man via inhibitory action on ACE and LDL oxidation.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.503-510
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• 2012

Microwave radar can penetrate cloud cover regardless of weather conditions and can be used day and night. Especially a A ground-based polarimetric scatterometer operating at multiple frequencies can continuously monitor the crop conditions. We analyzed scattering characteristics of rice and soybean using pauli decomposition method. Surface scattering (${\alpha}$) is the dominant component over the entire stages for all bands and pauli decomposition value was the highest for L-band. Double bounce scattering (${\beta}$) and volume scattering (${\gamma}$) were approximately equal for C-band and volume scattering was higher than double bounce scattering for X-band in rice field. In soybean, double bounce scattering becomes higher than volume scattering during the R2 stage (DOY 224) and there was a significant difference between the two components after the R4 stage (DOY 242) for L-band. The maximum growth stage of soybean can also be detected using L-band double bounce scattering. The peak of double bounce effect coincides with the peak of growth biophysical variables on DOY 271. We found that pauli decomposition can provide insight on the relative magnitude of different scattering mechanisms during the rice and soybean growth cycle.

• Journal of Fisheries and Marine Sciences Education
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• v.26 no.5
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• pp.935-940
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• 2014

To investigate effect of on sexual maturation in spotted seabass, Lateolabrax maculatus the sexual maturation, photoperiods were established to natural photoperiod, 9L:15D, 11L:13D, 13L:11D and 15L:9D. After rearing for 90 days from August 11 to November 10, gonadosomatic index (GSI) and hormones were analyzed. In the female, GSI was $1.07{\pm}0.09%$ in the natural photoperiod, $1.93{\pm}0.06%$ in 9L:15D, while the GSI of male was $0.75{\pm}0.05%$ in the natural photoperiod, $1.89{\pm}0.12%$ in 9L:15D and $0.22{\pm}0.05%$ in 15L:9D and the lowest in 15L:9D, respectively. The blood estradiol (E2) of female was $226.0{\pm}13.6pg/ml$ in the natural photoperiod, and the highest value of $296.3{\pm}15.0pg/ml$ in 9L:15D. The male $17{\alpha}20{\beta}OHP$ was similar to the female with $196.3{\pm}17.0pg/ml$ in the natural photo period and $133.0{\pm}15.5pg/ml$ in 9L:15D. The testosterone (T) of male was $259.3{\pm}33.1pg/ml$ in the natural photoperiod, but the hightest value of $370.5{\pm}27.5pg/ml$ in 9L:15D. These results provide basic information from sexual maturation of spotted seabass.