• Journal of the Korean Applied Science and Technology
• /
• v.39 no.5
• /
• pp.710-719
• /
• 2022

This study attempted to investigate the possibility of Passiflora caerulea extract as a cosmetic material by measuring its antioxidant activities and melanin biosynthesis-inhibiting effects. For this, the substance was extracted with 70% ethanol, and ABTS radical scavenging activities were measured, using the TEAC assay. In addition, cell viability through the neutral red assay, ROS inhibition and inhibition of melanin biosynthesis were analyzed, and the results found the followings: In terms of ABTS radical scavenging activities of the extract, dose-dependent scavenging activities were observed. In trolox used as a positive control group and 0.1 mg/mL, similar radical scavenging activities were found. The production of ROS through CFDA was inhibited in a dose-dependent fashion. Furthermore, inhibition of melanin biosynthesis induced by 𝛼-MSH was confirmed. Therefore, it is reasonable to conclude that Passiflora caerulea extract has a potential as a cosmetic ingredient.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.55 no.2
• /
• pp.91-101
• /
• 2022

In this study, we analyzed the compositional characteristics of Melosira nummuloides mass-cultured using Jeju lava seawater. M. nummuloides showed the highest growth rate when cultured for 14 days at 17-20℃ and 15,000 lx. Proximate composition of raw-material (RM) and freeze-dried M. nummuloides (FM) showed high ash content (65-72%), while ethanol-extracted M. nummuloides (EM) had low ash and high lipid contents. The predominantly occurring mineral, Si, was 334 g/kg in RM and 269 g/kg in FM, but EM contained only 1.97 g/kg. The ratio of essential amino acids was similar in RM (38.93%) and FM (36.89%) lower in EM (17.83%), but branched chain amino acids required for muscle metabolism was high (63.40%). The polyunsaturated fatty acids of EM (34.74%) was 11% more than that in RM (23.81%), and the ratio of omega-6 to omega-3 fatty acids was 1:3.6. Furthermore, the concentration of total chlorophyll was higher by 5.15 times (62.32 mg/g) and that of fucoxanthin by 7.06 times (11.02 mg/g) in EM than in RM (12.11, 1.56 mg/g, respectively). The mass cultivation and filtration of M. nummuloides using lava seawater has high prospects of commercialization as a competitive bio silica, cosmetic and healthy functional food material.

• Journal of the Korea Convergence Society
• /
• v.12 no.4
• /
• pp.87-94
• /
• 2021

While the shielding substances of radiation shields in medical institutions are beginning to be replaced by environmentally friendly materials, radiation protection according to the shielding properties of environmentally friendly substances is becoming an important factor rather than the existing lead shielding properties. Tungsten and barium sulfate are representative shielding materials similar to lead, and are made in sheets or fiber form with eco-friendly materials. Ytterbium is an impermeable material used as a fluorine compound in the dental radiation field. This study aims to evaluate the shielding performance in the x-ray shielding area by comparing the shielding properties of ytterbium by energy band and that of existing eco-friendly materials. When three types of shielding sheets were fabricated and tested under the same process conditions, the shielding performance of the medical radiation area was about 5 % difference from tungsten. Furthermore, shielding performance was superior to barium sulfate. In the cross-sectional structure of the shielding sheet, there was a disadvantage that the arrangement of particles was not uniform. Ytterbium oxide showed sufficient potential as a medical radiation shielding material, and it is thought that it can improve the shielding performance by controlling the particle arrangement structure and particle size.

• Steel and Composite Structures
• /
• v.44 no.1
• /
• pp.33-47
• /
• 2022

This paper presents a finite element model for predicting the monotonic behaviour of bolted endplate joints connecting steel-concrete composite walls and steel beams. The demountable Hollo-bolts are utilised to facilitate the quick installation and dismantling for replacement and reuse. In the developed model, material and geometric nonlinearities were included. The accuracy of the developed model was assessed by comparing the numerical results with previous experimental tests on hollow/composite column-to-steel beam joints that incorporated endplates and Hollo-bolts. In particular, the Hollo-bolts were modelled with the expanded sleeves involved, and different material properties of the Hollo-bolt shank and sleeves were considered based on the information provided by the manufacture. The developed models, therefore, can be applied in the present study to simulate the wall-to-beam joints with similar structural components and characteristics. Based on the validated model, the authors herein compared the behaviour of wall-to-beam joints of two commonly utilised composite walling systems (Case 1: flat steel plates with headed studs; Case 2: lipped channel section with partition plates). Considering the ease of manufacturing, onsite erection and the pertinent costs, composite walling system with flat steel plates and conventional headed studs (Case 1) was the focus of present study. Specifically, additional headed studs were pre-welded inside the front wall plates to enhance the joint performance. On this basis, a series of parametric studies were conducted to assess the influences of five design parameters on the behaviour of bolted endplate wall-to-beam joints. The initial stiffness, plastic moment capacity, as well as the rotational capacity of the composite wall-to-beam joints based on the numerical analysis were further compared with the current design provision.

• Korean Journal of Agricultural Science
• /
• v.49 no.3
• /
• pp.397-405
• /
• 2022

Castor oil cake is widely used as a raw material for organic fertilizers (OF) in Korea. Compared to other fertilizer raw materials, it is highly dependent on imports. In terms of replacing raw materials, dehydrated food waste powder (FDP) and castor oil cake have similar nutritional content, and if 30% is replaced, about 20% of the raw material cost can be saved. However, few studies on the effects on crop growth and soil properties when organic fertilizer and dry food waste powder are mixed and applied to the soil have been reported. The effects of an organic fertilizer made by mixing the commercial available organic fertilizer with dehydrated food waste (OF + FDP) on soil properties and the growth of two types of leafy vegetables (lettuce and young radish) were evaluated and compared with the performance of OF. The fresh weights of lettuce and young radish were the highest with OF amendment and stood at 114.3 and 119.0 g·plant^-1, respectively. These were followed by OF + FDP amendment, which produced 103.1 and 109.6 g·plant^-1, respectively. Compared to the control, OF and OF + FDP increased the lettuce fresh weights by about 69% and 52%, respectively, while the fresh weights of the radish were increased by about 223% and 207%, respectively. The soil pH, EC, total carbon content, and organic matter content in OF and OF + FDP increased. The mixture of dehydrated food waste powder and organic fertilizers is expected to improve soil quality and facilitate stable production of crops and contribute to the substitution of imported organic fertilizer raw materials.

• Advances in concrete construction
• /
• v.14 no.2
• /
• pp.93-102
• /
• 2022

In this study, limestone powder (LS) and fly ash (FA) were used as powder materials in self-compacting concrete (SCC) in increasing quantities in addition to cement, so that the two powders commonly used in the production of SCC could be compared in the same study. Considering the reduction of the maximum aggregate size in SCC, 10 mm or 16 mm was selected as the coarse aggregate size. The properties of fresh concrete were determined by slump flow (including T₅₀₀ time), V-funnel and J-ring experiments. The experimental results showed that as the amount of both LS and FA increased, the slump flow also increased. The increase in powder material had a negative effect on V-funnel flow times, causing it to increase; however, the increase in FA concretes was smaller compared to LS ones. The increase in the powder content reduced the amount of blockage in the J-ring test for both aggregate sizes. As the hardened concrete properties, the compressive and splitting strengths as well as the modulus of elasticity were determined. Longitudinal and transverse deformations were measured by attaching a special frame to the cylindrical specimens and the values of Poisson's ratio, initiation and critical stresses were obtained. Despite having a similar W/C ratio, all SCC exhibited higher compressive strength than NVC. Compressive strength increased with increasing powder content for both LS and FA; however, the increase of the FA was higher than the LS due to the pozzolanic effect. SCC with a coarse aggregate size of 16 mm showed higher strength than 10 mm for both powders. Similarly, the modulus of elasticity increased with the amount of powder material. Inelastic properties, which are rarely found in the literature for SCC, were determined by measuring the initial and critical stresses. Crack formation in SCC begins under lower stresses (corresponding to lower initial stresses) than in normal concretes, while critical stresses indicate a more brittle behavior by taking higher values.

• Journal of Software Assessment and Valuation
• /
• v.17 no.2
• /
• pp.31-38
• /
• 2021

In order to analyze the similarity of the source code object material, the source code on both sides must be able to be compiled and executed. In particular, in the case of hardware-integrated software, it is necessary to check whether the hardware interface matches. However, currently, the source code is provided in an incomplete state which is not original of source code used in developing steps. The complainant confirms that the executing characteristics are similar to their own in the expression and function of the output, and request an evaluation. When a source code compilation error occurs during the evaluation process, the experts draw a flowchart of the source code and applies the method of tracing the code flow for each function as indirect method. However, this method is indirect and the subjective judgment is applied, so there is concern about the contention of objectivity in the similarity evaluation result. In this paper, the problems of unverified source code similarity analysis and improvement directions are dealt with, through the analysis cases of source code disputes applied to embedded systems.

• Journal of Conservation Science
• /
• v.38 no.4
• /
• pp.301-313
• /
• 2022

We made a Korean white porcelain or Joseon Baekja jar and based on the raw materials used and reproductions of each stage, we aimed to compare and analyze the physicochemical changes of the raw materials such as clay at each manufacturing stage, as well as identify the characteristics and correlations. Although the basic main components of clay and glaze material are similar, their texture becomes denser in the process of bisque firing pottery (Chobeol-pyeon) and glaze firing pottery (Jaebeol-pyeon), and we confirmed that in addition to the tendency of increasing vitrification, low-temperature minerals such as mica and illite gradually disappeared, while high-temperature minerals such as cristobalite were newly created. This phenomenon has also been verified by the rapid decrease in absorption rate while the change in specific gravity was small. In addition, the color was greatly affected by the firing atmosphere, and the yellow-red chromaticity of the raw materials was higher during bisque firing but showed a rapidly decreasing characteristic during glaze firing. The value of magnetic susceptibility, which is related to iron (Fe) component, showed a tendency to decrease in glaze firing pottery. CT images were confirmed as a method that can indirectly estimate the change in the material properties of the object step-by-step for the entire object. In conclusion, the study of manufacturing stages of reproduction can provide basic data for scientific research on the estimation of porcelain and pottery making technology and changes in raw materials.

• Journal of the Korean Society of Radiology
• /
• v.16 no.4
• /
• pp.419-425
• /
• 2022

In the medical field, lead aprons are used to protect the human body from radiation. However, lead is a heavy metal that is harmful to the human body and the environment, so various shield are being developed. In this study, bismuth, which has a similar atomic number to lead, was set as a new material and the absorption rate according to thickness in the same energy region was compared and evaluated through Monte Carlo simulation. The same tendency was confirmed when the thickness of the lead shield was 0.25 mm, the thickness of the bismuth was 0.3 mm, when the lead was 0.50 mm, the bismuth was 0.60 mm, and when the lead was 0.75 mm, the bismuth was 0.90 mm. Therefore, it is reasonable to replace lead with bismuth in the shield material.

• Fashion & Textile Research Journal
• /
• v.24 no.6
• /
• pp.801-811
• /
• 2022

In this study, we constructed a database of dyeing concentrations of all reactive dyes used for dyeing linen according to the thickness of the linen fabric and attempted to improve the reproducibility of the dyeing process for the commercialization of linen fabric materials. Linen fabric is a natural cellulose material that is comfortable and suitable for eco-friendly trends. It is a typical summer material with excellent breathability and thermal conductivity, quick moisture absorption and dissipation, and a cool touch. Dyeability and fastness were evaluated depending on the thickness of the linen fabric using a monochlorotriazine (MCT) reactive dye and bifunctional yellow, red, and blue dyes. All three colors of the MCT reactive dye and bifunctional dyes exhibited a darker shade as the fiber thickness of the marker increased. Fastness to washing was excellent at grades 4-5 or higher, regardless of the color of the dye and the number of linen fabrics. Although some color-fastness differences were noted, with the color change occurring most frequently with blue color, the fastness variations with dye type were mostly similar. The results of this study are expected to facilitate the selection of reactive dyes according to the thickness of the linen fabric based on the basic data from the laboratory, which will aid in the mass production of linen fabric and benefit the fashion industry.