• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.549-550
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• 2006

The corrosion performance of a powder metallurgical aluminum alloy in aeronautical environments was studied for both as sintered and heat treated states. Sintered samples were obtained by uniaxial pressing of an Al-Cu-Mg prealloyed powder followed by liquid phase sintering. The heat treatments applied were T4 and T6. Corrosion behaviour was assessed by means of potentiodynamic polarization. Results for the equivalent commercial wrought counterpart, AA2024-T3, are also presented for comparison. Similar corrosion performance was observed for both as sintered and AA2024-T3 samples, while corrosion resistance of the PM materials was improved by the heat treatment, especially in the T4 state.

• The Journal of Pediatrics of Korean Medicine
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• v.38 no.3
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• pp.29-52
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• 2024

Objective This study aimed to evaluate the effect of herbal medicines on alopecia areata (AA). Methods We searched 10 Korean, English, Japanese, and Chinese databases for studies published until April 3, 2024. Randomized controlled trials (RCTs) assessing the effect of herbal medicines on AA were included. The Cochrane risk of bias tool was used to evaluate the quality of the studies. A meta-analysis was conducted according to outcome measurements, such as total effective rate (TER), full recovery rate, and recurrence rate, using the Review Manager software. Results Seventeen RCTs were included in this study, and the TER in the treatment group was 1.48 times higher than that in the control group [Risk ratio (RR): 1.48, 95% confidence interval (CI): 1.40~1.55, I² = 43%]. The full recovery rate was 2.25 times higher in the treatment group [RR: 2.25, 95% CI: 1.62~3.12, I² = 53%], and the recurrence rate was 0.22 times lower, than that of the control group [RR: 0.22, 95% CI: 0.070~0.68, I² = 0%]. Four studies reported that there were no adverse events. Four studies reported mild gastric discomfort, a mild increase in alanine aminotransferase (ALT), and constipation in the treatment group. Conclusions Our meta-analysis showed that herbal medicines are significantly effective in treating AA. However, owing to the low quality of the included studies, future clinical studies are required to determine their potential for clinical applications.

• Herbal Formula Science
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• v.32 no.1
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• pp.51-61
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• 2024

Objectives : This study induced oxidative stress in HepG2 cells by treating them with AA+iron and investigated the effects of forsythia suspensa extract on this stress, as well as elucidated the molecular mechanisms underlying its hepatoprotective effects. Methods : To confirm the antioxidative effects of FSE, HepG2 cells were induced with AA+iron to induce oxidative stress, followed by MTT assay. Additionally, the effect of FSE in reducing the increased ROS levels and mitochondrial damage induced by AA+iron in HepG2 cells was confirmed using FACS. Furthermore, western blot analysis were conducted to investigate the molecular mechanisms underlying the hepatoprotective effects of FSE. Results : FSE increased the decreased cell viability induced by AA+iron. Additionally, FSE normalized the expression of apoptosis-related proteins induced by AA+iron. The elevated ROS levels in HepG2 cells induced by AA+iron were reduced by FSE, and the increase in Rh123-negative cells induced by AA+iron was attenuated by FSE. Moreover, FSE activated the protein expression of AMPK and its related phosphorylating enzymes, LKB1 and ACC. Furthermore, FSE activated YAP and its upstream phosphorylating enzyme, LATS1. Conclusions : These results demonstrate that FSE has an inhibitory effect on oxidative stress induced by AA+iron and may have potential hepatoprotective effects.

• Food Science and Preservation
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• v.31 no.2
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• pp.315-323
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• 2024

This study aims to confirm the anti-inflammatory activities of acemannan and aloesin, which have been studied for various efficacies at various mixed sample ratios. The mixed samples were mixed at a ratio of 1:1 (AA-1), 1:2 (AA-2), 1:3 (AA-3), 2:1 (AA-4), and 3:1 (AA-5). Seven samples were evaluated for their cytotoxic ability on macrophages, and the results showed that all cell viability was over 90% at a concentration of 100 ㎍/mL. First, due to the NO production inhibitory activity, a better inhibitory effect was achieved when using a mixed sample rather than a single material. Afterward, the activity of inhibiting the production of PGE₂, TNF-α, and IL-6 was confirmed using a mixed sample. It was confirmed that AA-2 had the best inhibitory activity on producing PGE2, TNF-α, and IL-6 rather than AA-1, AA-3, AA-4, and AA-5. For this reason, experiments were conducted using AA-2 to determine the protein expression levels of iNOS and COX-2, which are inflammation-related proteins. It was confirmed that AA-2 inhibited iNOS and COX-2 protein expression by 25.01% and 27.27%, respectively, compared to the LPS-alone treatment group. In conclusion, the mixed sample of acemannan and aloesin is judged to have anti-inflammatory activity and can potentially to be used as a functional material.

• Herbal Formula Science
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• v.32 no.1
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• pp.99-109
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• 2024

Objectives : In this study, we investigated the cytoprotective effect of Eriobotrya japonica L. (EJ) extract against Arachidonic acid (AA)+iron-induced oxidative stress. Methods : To confirm the cytoprotective effect of EJ against AA+iron-induced oxidative stress in HepG2 cells, it was evaluated by MTT assay, immunoblot anaylsis, and Calcein-AM/propidium iodide (PI) staining. Additionally, the mechanism of action of the cytoprotective effect was evaluated through molecular mechanisms. Results : EJ (100 ㎍/mL) inhibited Arachidonic acid (AA)+iron-induced cell death in a concentration-dependent manner. It also inhibited AA+iron-induced mitochondrial dysfunction and ROS production. EJ activated the LKB1-AMPK signaling pathway. Conclusions : In conclusion, EJ has the ability to protect liver cells from oxidative stress, indicating that it is related to AMPK-LKB1 signaling pathways.

• Journal of Animal Science and Technology
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• v.66 no.1
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• pp.145-155
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• 2024

This study was conducted to determine the effects of amino acid (AA) supplementation in low-protein (LP) diets on growth performance and nitrogen (N) excretion. A total of 175 7-day-old Ross 308 male broilers, with a mean body weight (BW) of 165 g (standard deviation = 11.2 g), were grouped into five blocks by BW and allocated to seven treatments according to a randomized complete block design with five replicate cages at five birds per cage. Dietary treatments comprised a control diet containing 20.0% crude protein (CP) and six LP diets containing either 18.5% or 17.0% CP. These LP diets were supplemented with either no AA supplementation, indispensable AA, or both indispensable and dispensable AA (glutamic acid and glycine). Birds were fed experimental grower diets from day 7 to 21 and then commercial finisher diets until day 28. During the grower period (day 7 to 21), birds fed LP diets supplemented with indispensable AA exhibited greater (p < 0.05) BW, body weight gain (BWG), feed intake (FI), and gain-to-feed ratio (G:F) than birds fed LP diets without crystalline AA and were comparable to birds fed the control diet. During the finisher period (day 21 to 28), birds fed LP diets supplemented with indispensable AA showed greater (p < 0.05) BW than birds fed LP diets without crystalline AA, and their growth performance was comparable to birds fed the control diet. Throughout the overall period, supplementing indispensable AA in LP diets resulted in elevated (p < 0.05) BWG, FI, and G:F more than those of LP diets without crystalline AA and were comparable to those of the control diet. Supplementing indispensable AA in LP diets decreased amount and coefficient of N excretion as much as the control diet. Dispensable AA supplementation in LP diets did not influence growth performance and N excretion. In conclusion, supplementing indispensable AA in LP diets maintains growth performance and N excretion until the dietary CP lowers from 20.0% to 17.0% during the grower period. As long as dietary CP is above 17.0%, dispensable AA may not be deficient in LP diets during the grower period.

• Journal of Marine Life Science
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• v.9 no.1
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• pp.22-32
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• 2024

The purpose of this study was to determine the effect of external biologger attachment methods on the blood parameters and attachment efficiency of spotted sea bass Lateolabrax maculatus (mean body weight 2630.8 g). The fish were tagged using four different external attachment methods with dummy biologgers: no attachment (control), anchor attachment (AA), monofilament attachment (MA), and silicon tube attachment (SA), each with triplicates. Blood indices and biologger attachment efficiency were assessed on days 1, 7, 14, 28, 56, and 84 after attachment. The concentrations of hematocrit, Na⁺, Cl^-, glutamic pyruvic transaminase and total protein, and the activity of superoxide dismutase in blood were not affected by the external attachment method of biologger. The concentrations of glutamic oxaloacetic transaminase (day 1 of attachment), hemoglobin (day 56) and total cholesterol (day 56 and 84) in AA group, the concentrations of glucose and cortisol (day 14) and total cholesterol (day 84) in MA group showed significantly higher than those of control (p<0.05). During the experiment period, the SA group had no differences from the control in all blood properties. The biologger attachment efficiencies of the AA, MA, and SA groups after 84 days were 0.0%, 33.3%, and 100.0%, respectively. These results indicate that the optimum external biologger attachment method under our experimental conditions is SA type.

• Transactions of Materials Processing
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• v.16 no.8
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• pp.582-589
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• 2007

This paper is related to an analysis on the surface expansion in backward can extrusion process using spherical punches. It is generally known that the backward can extrusion process usually experiences severe normal pressure and heavy surface expansion. This is a reason why the backward can extrusion process is one of most difficult operations among many forging processes. Different punch nose radii have been applied to the simulation to investigate the effect of punch nose radius on the surface expansion, which is a major effort in this study. AA 2024 aluminum alloy is selected as a model material for investigation. Different frictional conditions have also been selected as a process parameter. The pressure applied on the punch has been also investigated since heavy surface expansion as well as high normal pressure on the tool usually leads to severe tribological conditions along the interface between material and tool. The simulation results are summarized in terms of surface expansion at different reduction in height, deformation patterns including strain distributions and maximum pressure exerted on the workpiece and punch, the effect of punch nose radius and the frictional condition on the surface expansion and the location and magnitude of maximum pressure exerted, respectively.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.148-158
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• 2019

The corrosion protection of AA2024 PPy coated samples doping with nanosized metal oxides, including $TiO_2$ and $CeO_2$ nanoparticles and $Nd_2O_3$ nanorods, during exposure to the solutions of 0.1 M $H_2SO_4$ and 3.5% NaCl was evaluated by electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques. The nanorods of $Nd_2O_3$ were synthesized by cathodic pulse electrochemical deposition technique. The barrier properties of the different PPy coatings containing nanosized metal oxides immersed in $H_2SO_4$ solution were ranked as follows: $Nd_2O_3$ > $TiO_2$ > $CeO_2$. Therefore, the $Nd_2O_3$ coating sample provided the highest corrosion protection at any time of immersion up to 72 hours after immersing in $H_2SO_4$ solution. On the other hand, the $CeO_2$ coating sample displayed the best anticorrosive properties among the other coating samples after immersion in NaCl solution up to 28 days. This is due to the inhibition effect of cerium ions on aluminum alloys at near-neutral solutions.

• Journal of the Korean institute of surface engineering
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• v.57 no.1
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• pp.8-13
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• 2024

Anodizing of Al6061 alloy was conducted in two different electrolytes of 20% sulfuric acid and 8% sulfuric acid + 3 % oxalic acid solutions at a constant current or decreasing current density conditions, and its dielectric breakdown voltage was measured. The surface morphology of anodic oxide films was observed by TEM and thermal treatment was carried out at 400 ℃ for 2 h to evaluate the resistance of the anodic oxide films to crack initiation. The anodic oxide film formed in 8% sulfuric acid + 3 % oxalic acid solution showed higher dielectric breakdown voltage and better resistance to crack initiation at 400 ℃ than that formed in 20% sulfuric acid solution. The dielectric breakdown voltage increased 6 ~12% by applying decreasing current density comparing with a constant current density.