• Journal of Convergence for Information Technology
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• v.11 no.7
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• pp.264-271
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• 2021

In this study, the antioxidant and anti-inflammatory properties of Sargassum patens extracts were identified. Antioxidant experiments included polyphenol concentration measurements, flavonoid concentration measurements, DPPH experiments, ABTS experiment NO experiments, and FRAP experiments. For polyphenols, 18.99±0.69 mg/g was shown. Flavonoids showed 11.89±1.16 mg/g. The DPPH experiment showed an antioxidant function of 19.78 mg ascorbic acid/g extract, the ABTS experiment showed an antioxidant function of 63.64 mg ascorbic acid/g extract, and the NO experiment showed an antioxidant function of 7.966 mg ascorbic acid/g extract. In FRAP, 1 mg of the moxibustion extract showed a reduction of 2.089 ㎍ of ascorbic acid. In the meantime, cell experiments showed cytotoxicity and anti-inflammatory functions against inflammation induced by LPS. In cytotoxicity experiments, Sargassum patens extracts showed a cell survival rate of more than 80% at all concentrations, and an inflammatory inhibition of 30.64±0.23% at a concentration of 100 ㎍/mL. These results indicate that Sargassum patens extract is available as an anti-inflammatory cosmetic material.

• Tribology and Lubricants
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• v.34 no.6
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• pp.241-246
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• 2018

This research addresses the improvement of tribo-systems, specifically regarding the reduction of friction and wear through tribo-coupling between tetrahedral amorphous carbon (ta-C) with different types of counterpart materials, namely bearing steel (SUJ2), tungsten carbide (WC), stainless steel (SUS304), and alumina ($Al_2O_3$). A second variable in this project is the utilization of different values of duct bias voltage in the deposition of the ta-C coating - 0, 5, 10, 15, and 20 V. The results of this research are expected to determine the optimum duct bias and best counter materials associated with ta-C to produce the lowest friction and wear. Results obtained reveal that the tribo-couple between the ta-C coating and SUJ2 balls produces the lowest friction coefficient and wear rate. In terms of duct bias changes, deposition using 5 V produces the most optimum tribological behavior with lowest friction and wear on the tribo-system. In contrast, the tribo-couple between ta-C with a WC ball causes penetration through the coating surface layer and hence high surface delamination. This study demonstrates that the most effective ta-C coating duct bias is 5 V associated with SUJ2 counter material to produce the lowest friction and wear.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.2
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• pp.55-62
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• 2021

This study aims to reduce the rancid odor generated during the fermentation process of kimchi by inserting zinc oxide (ZnO) into an inorganic porous material with a high surface area to decompose or adsorb the fermentation odor. ZnO activated by the presence of moisture exhibits decomposition of rancid odors. Mixed with Titanium dioxide (TiO₂), a photocatalyst. To manufacture the packaging liner used in this study, NaOH, ZnCl₂, and TiO₂ powder were placed in a tank with diatomite and water. The sludge obtained via a hydrothermal ultrasonication synthesis was sintered in an oven. After being pin-milled and melt-blended, the powders were mixed with linear low-density polyethylene (L-LDPE) to make a masterbatch (M/B), which was further used to manufacture liners. A gas detector (GasTiger 2000) was used to investigate the total amount of sulfur compounds during fermentation and determine the reduction rate of the odor-causing compounds. The packaging liner cross-section and surface were investigated using a scanning electron microscope-energy dispersive X-ray spectrometer (SEM-EDS) to observe the adsorption of sulfur compounds. A variety of sulfur compounds associated with the perceived unpleasant odor of kimchi were analyzed using gas chromatography-mass spectrometry (GC-MS). For the analyses, kimchi was homogenized at room temperature and divided into several sample dishes. The performance of the liner was evaluated by comparing the total area of the GC-MS signals of major off-flavor sulfur compounds during the five days of fermentation at 20℃. As a result, Nano-grade inorganic compound liners reduced the sulfur content by 67 % on average, compared to ordinary polyethylene (PE) foam liners. Afterwards SEM-EDS was used to analyze the sulfur content adsorbed by the liners. The findings of this study strongly suggest that decomposition and adsorption of the odor-generating compounds occur more effectively in the newly-developed inorganic nanocomposite liners.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.9
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• pp.199-206
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• 2019

Experimental study on the durability characteristics to examine the feasibility of concrete with high water-tightness and self-healing performance to minimize maintenance of concrete for artificial ground is as follows. 1) When blending agent, swelling agents, and curing accelerator were added on the ternary system cement with blast-furnace slag fine particles and fly ash to give a self-healing property, higher blending strengths by 82% at design standard strength of 24MPa and by 74% at design strength of 30MPa, respectively could be obtained. 2) The permeability test for the specimens having high water-tightness and no shrinkage showed that the permeability was reduced at maximum of 98%. However, the permeability was decreased as the design strength was increased, showing the reduction rate of 87% at the design strength of 50MPa. 3) The depth of carbonation of blast-furnace slag and fly ash was increased in all the specimens compared with those of OPC only. However, as the material age was increased, carbonation penetration depth was decreased compared with the reference blend. 4) Compared with the reference blending using only OPC, the freeze-thaw resistance was higher in the case of blending with 40% of blast-furnace slag and 10% of fly ash at the design standard strength of 50MPa. In addition, the freeze-thaw resistance in general was superior in the design standard strength of 50MPa with the lower water-binder ratio (W/B) as compared with the design standard strength of 24MPa and 30MPa with the high water-binder ratios.

• Steel and Composite Structures
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• v.37 no.6
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• pp.711-731
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• 2020

This paper deals with free vibration of FG sandwich annular sector plates on Pasternak elastic foundation with different boundary conditions, based on the three-dimensional theory of elasticity. The plates with simply supported radial edges and arbitrary boundary conditions on their circular edges are considered. The influence of carbon nanotubes (CNTs) waviness, aspect ratio, internal pores and graphene platelets (GPLs) on the vibrational behavior of functionally graded nanocomposite sandwich plates is investigated in this research work. The distributions of CNTs are considered functionally graded (FG) or uniform along the thickness of upper and bottom layers of the sandwich sectorial plates and their mechanical properties are estimated by an extended rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. The core of structure is porous and the internal pores and graphene platelets (GPLs) are distributed in the matrix of core either uniformly or non-uniformly according to three different patterns. The elastic properties of the nanocomposite are obtained by employing Halpin-Tsai micromechanics model. A semi-analytic approach composed of 2D-Generalized Differential Quadrature Method (2D-GDQM) and series solution is adopted to solve the equations of motion. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. Some new results for the natural frequencies of the plate are prepared, which include the effects of elastic coefficients of foundation, boundary conditions, material and geometrical parameters. The new results can be used as benchmark solutions for future researches.

• Journal of Microbiology and Biotechnology
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• v.32 no.9
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• pp.1146-1153
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• 2022

Many probiotic species have been used as a fermentation starter for manufacturing functional food materials. We have isolated Bifidobacterium animalis subsp. lactis LDTM 8102 from the feces of infants as a novel strain for fermentation. While Glycine max has been known to display various bioactivities including anti-oxidant, anti-skin aging, and anti-cancer effects, the immune-modulatory effect of Glycine max has not been reported. In the current study, we have discovered that the extract of Glycine max fermented with B. animalis subsp. lactis LDTM 8102 (GFB 8102), could exert immuno-modulatory properties. GFB 8102 treatment increased the production of immune-stimulatory cytokines in RAW264.7 macrophages without any noticeable cytotoxicity. Analysis of the molecular mechanism revealed that GFB 8102 could upregulate MAPK2K and MAPK signaling pathways including ERK, p38, and JNK. GFB 8102 also increased the proliferation rate of splenocytes isolated from mice. In an animal study, administration of GFB 8102 partially recovered cyclophosphamide-mediated reduction in thymus and spleen weight. Moreover, splenocytes from the GFB 8102-treated group exhibited increased TNF-α, IL-6, and IL-1β production. Based on these findings, GFB 8102 could be a promising functional food material for enhancing immune function.

• Computers and Concrete
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• v.29 no.1
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• pp.15-29
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• 2022

Concrete-filled steel tubes (CFSTs) are increasingly used as composite sections in structures owing to their excellent load bearing capacity. Therefore, predicting the mechanical behavior of CFST sections under axial compression loading is vital for design purposes. This paper presents the first study on the nonlinear analysis of heated CFSTs with high-strength concrete core containing steel fiber and waste tire rubber under axial compression loading. CFSTs had steel fibers with 0, 1, and 1.5% volume fractions and 0, 5, and 10% rubber particles as sand alternative material. They were subjected to 20, 250, 500, and 750℃ temperatures. Using flow rule and analytical analysis, a model is developed to predict the load bearing capacity of steel tube, and hoop strain-axial strain relationship, and axial stress-volumetric strain relationship of CFSTs. An elastic-plastic analysis method is applied to determine the axial and hoop stresses of the steel tube, considering elastic, yield, and strain hardening stages of steel in its stress-strain curve. The axial stress in the concrete core is determined as the difference between the total experimental axial stress and the axial stress of steel tube obtained from modeling. The results show that steel tube in CFSTs under 750℃ exhibits a higher load bearing contribution compared to those under 20, 250, and 500℃. It is also found that the ratio of load bearing capacity of steel tube at peak point to the load bearing capacity of CFST at peak load is noticeable such that this ratio is in the ranges of 0.21-0.33 and 0.31-0.38 for the CFST specimens with a steel tube thickness of 2 and 3.5 mm, respectively. In addition, after the steel tube yielding, the load bearing capacity of the tube decreases due to the reduction of its axial stiffness and the increase of hoop strain rate, which is in the range of about 20 to 40%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.7
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• pp.105-112
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• 2021

Reduction of weld distortions and increase in productivity are some of the major goals of the shipbuilding industry. To address these issues, many researchers have attempted to apply new welding processes. In the shipbuilding industry, steel is the candidate material of choice owing to its good weldability. However, conventional welding techniques are not feasible for avoiding welding problems. Tip-rotating arc welding is one of the high-efficiency welding process that has several advantages, such as high welding speed, high melting rate, low heat input, and less distortion. The present study investigates the influence of the welding variables on the weld characteristics of tip-rotating arc welding. Welding was performed using EH36 as the base metal and SM-70s as the filler metal, which are widely used in shipbuilding. Basic experiments were conducted to understand the effects of the major welding variables, such as welding and tip-rotating speeds. The distortion and mechanical properties of the optimal welding conditions were used to evaluate the tip-rotating arc welding performance. Consequently, the feasibility of the tip-rotating arc welding process for joining steel components was investigated, so that the optimized welding conditions could be applied directly to ship body welding to enhance the quality of the welded joints.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.182-192
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• 2022

Brittle feature is one of the fracture behaviors of structure s and has a great influence on the seismic performance of structure materials. The load velocity acts as one of the main causes of brittle fracture, and in particular, in situations such as earthquakes, a high load velocity acts on buildings. However, most of the seismic performance evaluation of the domestic and external steel connections is conducted through static experiments. Therefore, there is a possibility that brittle fracture due to factors such as degradation of material toughness and reduction of maximum deformation rate due to high load velocity during an earthquake was not sufficiently considered in the existing seismic performance evaluation. This study conducts a static test at a low load velocity according to the existing experimental method and a dynamic test at a high load velocity using a shaking table, respectively. It compares and analyzes the fracture shape and structural performance according to the results of each experiment, and finally analyzes the effect of the load velocity size on the seismic performance of the connection.

• Food Science of Animal Resources
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• v.43 no.1
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• pp.124-138
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• 2023

This study was carried out to determine the effects of adding pistachio shell (PIS), pomegranate hull (POM), and olive pulp (OP) to the diet on milk amino acid and fatty acid parameters in Awassi sheep. In the study, 40 head of Awassi sheep, which gave birth at least twice, were used as animal material. Sheep were fed a control diet without added byproducts (CON), rations containing PIS, POM, and OP. Milk amino acid profile was determined by liquid chromatography-tandem mass spectrometry, milk fatty acid gas chromatography-flame ionization detection device. There was a dramatic reduction in alanine, citrulline, glutamine, glutamic acid, glycine, leucine, ornithine and alphaaminoadipic acid in the research groups. In the PIS group, argininosuccinic acid, gammaminobutyric acid, beta-alanine and sarcosine; In the POM group, asparagine, gammaminobutyric acid, beta-alanine, and taurine; In the OP group, a significant positive increase was found in terms of alanine, histidine, gammaminobutyric acid, and taurine amino acids. The applications in the study did not have a statistically significant effect on the ratio of short, medium and long chain fatty acids in milk (p>0.05). In the presented study, it was determined that PIS, POM, and OP, which were added to the sheep rations at a rate of 5%, caused significant changes in the milk amino acid profiles. In this change in milk amino acid profiles, the benefit-harm relationship should be considered.