• Korean Journal of Environmental Biology
• /
• v.37 no.1
• /
• pp.31-41
• /
• 2019

The toxic dinoflagellate Gymnodinium catenatum isolated from the southern coast of Korea was described under light and scanning electron microscopy, and its large subunit (LSU) rDNA was sequenced. In addition, the effects of temperature and salinity on its growth were investigated. The cells of G. catenatum, as viewed under the electronic microscope, were green-brown color, $38.1-77.4{\mu}m$ in length and $26.1-40.8{\mu}m$ in width. The epicone was conical, while the hypocone was trapezoidal. The nucleus was located at the central part of the cell. The apical groove was horseshoe-shaped and small pores were irregularly distributed on the cell surface. Molecular phylogeny based on LSU rDNA gene sequences showed that the Korean G. catenatum and previously reported species formed a monophyletic clade within Gymnodinium sensu stricto clade. The maximum growth rate of $0.37day^{-1}$, was obtained at $25^{\circ}C$ and 35 psu, and the maximum cell density of $1,073cells\;mL^{-1}$, was observed at $20^{\circ}C$ and 25 psu. However, G. catenatum did not grow at temperature < $15^{\circ}C$ and < $30^{\circ}C$. These results suggest that environmental conditions of summer and autumn in the southern coast of Korea may be favorable for the growth of G. catenatum.

• Korean Journal of Heritage: History & Science
• /
• v.49 no.2
• /
• pp.158-171
• /
• 2016

The observation and analysis results of 9 glass bead samples collected from Oc Eo site in Vietnam, an outport of the ancient port city Funan in East Asia, are as follows. The type of glass beads is round, the colors are reddish brown, greenish blue, green, black and purplish blue, and the chemical composition is soda glass group. This means that they are similar in type, color and chemical compositions to glass beads from the ancient Korean peninsula. There are limitations in data because the glass beads are not from excavation investigation but from earth surface investigation. But it is significant that similar making technique and chemical composition are being observed in both the glass beads from Oc Eo and those of Korea. According to "Nihon Shoki" Kinmeiki, Baekje king sent Funan's goods and 2 slaves to Japan in 543. It is clear that there were direct or indirect exchanges between Baekje and Funan. The possibility has grown that glass beads could be included among goods.

• Korean Journal of Heritage: History & Science
• /
• v.36
• /
• pp.267-297
• /
• 2003

The plain coarse pottery from the Unjeonri Bronze Age relic sites in the Cheonan, Korea were studied on the basis of clay mineralogy, geochemistry and archaegeological interpretations. For the research, the potteries are utilized at the analysis for 6 pieces of plain coarse potteries. Color of the these potteries are mainly light brown, partly shows the yellowish brown to reddish brown. The interior, surface and inside of the pottery appear as different colors in any cases. Original source materials making the Unjeonri potteries are used of mainly sandy clay soil with extreme coarse grained irregularly quartz and feldspar. The magnetic susceptibility of the Unjeonri pottery range from 0.20 to 1.20. And the Unjeonri soil's magnetic susceptibility agree almost with 0.20 to 1.30. In the same magnetization of soil and pottery, the results revealed that the Unjeonri soil and low material of pottery are same produced by identical source materials. The Unjeonri potteries and soil are very similar patterns with all characteristics of soil mineralogy, geochemical evolution trend. The result seems to be same relationships between the behavior and enrichment patterns on the basis of a compatible and a incompatible elements. Consequently, the Unjeonri potteries suggest that made the soil to be distributed in the circumstance of the relic sites as the raw material are high in a greater part. In the Unjeonri soil, the kaolinite is common occurred minerals. However, in the Unjeonri pottery, the kaolinite was not detected in all broken pieces. The kaolinite was presumed to destroy crystal structure during the firing processes of over $550^{\circ}C$. The quartz is phase transition from ${\alpha}$-quartz to ${\beta}$-quartz at $573^{\circ}C$, but the Unjeonri pottery did not investigated any phase transition evidences of quartz. The chorite was detected within the mostly potteries and soils. As the results, the Unjeonri potteries can be interpreted by not experiencing a firing temperature over $800^{\circ}C$. The colloidal and cementing materials between the quartz and low materials during the heating did not exist in the internal part of the potteries. An any secondary compounds by heating does not appear within the crack to happen during the dry of the pottery. The hyphae group are kept as it is with the root tissue of an organic matters to live in the swampy land. In the syntheses of all results, the general firing condition to bake and make the Unjeonri pottery is presumed from $550^{\circ}C$ to $800^{\circ}C$. However, the firing condition making the Unjeonri pottery can be different firing temperature partially in one pottery. Even, the some part of the pottery does not take a direct influence on the fire.

• Journal of Conservation Science
• /
• v.37 no.2
• /
• pp.167-178
• /
• 2021

For the preservation and efficient content sharing of 5 volumes (2,866 pages) of Yu Kil-Chun's book published in 1971, which provides an important collection of data for the study of modern Korean history during the late 19th century (enlightenment period of Joseon dynasty). The books were purchased and its preservation status investigated and documented electronically by scanning for permanent preservation of content and to determine the condition of preservation at the time of documentation. The degree of deterioration and damage, such as discoloration, hardening, breakage, and damage in these 50 years old modern printed books was quantified through image analysis and made attempts to visualize the damaged areas. It was observed that the degree of deterioration and damage depended on the material and the surface condition of the paper used, the degree of exposure to light, and the storage environment. The comparison of the preservation status at the time of the photographing (or scanning) and judgment as to whether or not the image under investigation was artificially modified was accomplished by comparing the electronically documented images of Seoyugyeonmun (西遊見聞) in Volume 1 of Yu Kil-Chun's works with images provided on other websites. Practical problems encountered while considering the effective preservation of electronically documented data and publicly sharing it, in the course of this study, with other academic researchers around the world were also summarized.

• Journal of the Korean Geotechnical Society
• /
• v.37 no.2
• /
• pp.5-17
• /
• 2021

The Moon has been an attractive planet as an outpost for deep space exploration since He-3 and water ice which can be used as energy resources were discovered. In-Situ Resource Utilization (ISRU) construction material fabrication method is required for sustainable space planet exploration. In this paper, the possibility of microwave sintering technology for construction material fabrication was evaluated using lunar regolith that can be easily collected from the Moon surface. Experimental assessment of the influence factors on microwave sintering was conducted using a hybrid sintering system for efficient processing. The heat distribution in the furnace was observed using thermal paper that is coated with a material formulated to change color when exposed to heat. Based on this result, sintered cylindrical KLS-1s with a diameter of 1 cm and a height of 2 cm were fabricated. Densities were measured for the sintered KLS-1s under rotating turntable conditions that have an effect of microwave dispersion. The more dielectrics were arranged, the more microwaves were dispersed reducing the heat concentration, and thus a uniformity of sintered KLS-1s was enhanced.

• Journal of dental hygiene science
• /
• v.21 no.2
• /
• pp.96-103
• /
• 2021

Background: We aimed to investigate the effect of Citrous limon extract (CLE) on oxidative stress-induced cytotoxicity and nitric oxide (NO) generation and the tooth bleaching effect of CLE as a substitute for hydrogen peroxide (H₂O₂) and determine the feasibility and application of CLE as a safe and effective natural tooth bleaching agent. Methods: The protective effect of CLE on H₂O₂-induced cytotoxicity in Raw264.7 macrophages was investigated by the MTT assay. The inhibitory effect of CLE on the generation of H₂O₂-induced NO was confirmed by the NO assay, and the changes in inducible nitric oxide synthase (iNOS) protein expression were confirmed by western blotting. Stained bovine teeth were treated with/without 15% and/or 35% CLE and H₂O₂, 15% sodium bicarbonate (NaHCO₃) for 3 hours, and were irradiated with/without bleaching light (BL) for 15 minutes. The color change of the treated bovine tooth surface was measured using a colorimeter. Results: The viability of Raw264.7 cells treated with each concentration of CLE and 500 μM H₂O₂ significantly increased as CLE increased, and NO generation and iNOS protein expression were significantly reduced in cells treated with 300 ㎍ CLE+/500 μM H₂O₂+ and 300 ㎍ CLE+/500 μM H₂O₂+/150 ㎍ NaHCO₃+. The bleaching effect of 35% CLE+ was higher than that of 15% CLE+ and 15% NaHCO₃+, and the effect was similar to that of 15% H₂O₂+. The 35% CLE+/15% NaHCO₃+ showed the greatest bleaching effect and was higher than that of the groups irradiated with the BL. The greatest bleaching effect was observed with 35% CLE+/15% NaHCO₃+, followed by 35% H₂O₂+/BL+. Conclusion: CLE inhibited oxidative stress-induced cytotoxicity and NO generation in Raw264.7 cells and, could replace H₂O₂, which causes side effects and risks in teeth breaching treatment. It showed greatest teeth bleaching effect when combined with NaHCO₃. CLE is an effective and safe natural tooth bleaching substitute.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.37 no.4
• /
• pp.177-185
• /
• 2021

Clinical applications of translucent zirconia as well as traditional zirconia (3 mol% yttria stabilized tetragonal zirconia polycrystal, 3Y-TZP) are increasing. For this reason, studies on factors affecting the optical properties of dental zirconia have been continuously reported. The optical effect of dental zirconia may vary depending on the yttria content, the thickness of the prosthesis, the sintering process, polishing, glazing and cementation in laboratory and clinical procedures. Increasing the yttria concentration can reduce the masking effect. Translucency decreases as the thickness of the restoration increases, but the required thickness may vary depending on the properties of the zirconia block. The high-speed sintering method can shorten the manufacturing time, but in some cases, the translucency of the prosthesis may decrease. In addition, the optical properties can be affected by the surface roughness of zirconia and the polishing process. The use of an appropriate colored cement can help with the masking effect of zirconia and can be useful for color matching for more esthetic results.

• Journal of Bio-Environment Control
• /
• v.31 no.4
• /
• pp.393-400
• /
• 2022

Postharvest quality of sweet pepper fruits was mainly defined as external appearance, i.e., shape, fruit weight and surface color. These quality traits tend to involve esthetic appeal, it disregards gustatory properties and nutritional value. However, comparative studies according to the marketability of sweet pepper fruits are insufficient. This study was carried out to compare the physicochemical components, antioxidant activity and carotenoid contents of marketable and unmarketable sweet pepper fruits (Capsicum annuum L.). Physicochemical components (proximate composition, minerals and total phenolic contents) and antioxidant activities using various methods were investigated. The proximate composition values (%) of marketable and unmarketable fruits were: moisture (90.28 and 90.29), ash (0.74 and 0.26), crude protein (0.67 and 0.72), crude lipid (0.38 and 0.32). There were no significant differences in antioxidant activity, while total phenolic content was higher in marketable fruit. Carotenoids contents were 29.3 ± 2.6 and 31.9 ± 2.9 ㎍·g^-1 in marketable and unmarketable fruits respectively, and identified β-carotene, violaxanthin, neoxanthin, and zeaxanthin. Lutein and capsaicin were not detected. In this study, potential value of unmarketable sweet pepper fruit could be identified to be applied as a food ingredient and functional food material.

• Journal of Life Science
• /
• v.32 no.5
• /
• pp.355-361
• /
• 2022

Melanin pigments are the main cause of skin color. They are produced in melanocytes and then transferred to keratinocytes, which eventually gives the skin surface a variety of colors. Although many skin-lightening or depigmenting agents have been developed, the demand for materials to reduce pig- mentation is still increasing. Here, we tried to find materials for skin-lightening or depigmentation using natural compounds and found that mistletoe (Viscum album var. coloratum) extracts (ME) had an inhibitory effect on tyrosinase activity. As a result, ME significantly reduced pigmentation in human primary melanocytes. In addition, a promoter reporter assay revealed that ME inhibited the transcription of microphthalmia-associated transcription factor (MITF), melanophilin (MLPH), tyrosinase-related protein-2 (TRP-2), and tyrosinase (TYR) genes in HM3KO melanoma cells. In addition, ME decreased the protein level for pigmentation-related molecules, such as TYR and TRP-1. Furthermore, it markedly inhibited the melanogenesis of zebrafish embryos, an in vivo evaluation model for pigmentation. To elucidate the action mechanism of ME, we investigated its effects on intracellular signaling. Eventually, the ME dramatically decreased the phosphorylation of the cAMP responsive element binding protein (CREB), AKT, and ERK. The data suggest that ME may inhibit the melanogenesis pathway by regulating the signaling pathway related to pigmentation. Taken together, these data propose that ME can be developed as a depigmenting or skin-lightening agent.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.22 no.2
• /
• pp.121-127
• /
• 1977

Leaf burning due to nitrofenapplication was characterized as brown color spot appearing on the leaf sheath and blade. The spots predominantly appeared around 5-7 cm high above soil surface regardless of different particle size, formulation, application method, or water level. Magnitude and frequency of burn spots increased somewhat as the granular size gets finer, by higher water level, or in transplanted rice compared to directly sown rice when applied at 7 leaf-stage, but there was no indication of increase in leaf burning due to clinging of floating dust to rice plant. When collections from local distributor's stock of TOK 7G, a granular formulation of nitrofen, were analyzed for particle size composition, 98.9% by weight ranged between 9 to 35 meshes, and only about 0.08% by weight was of particles finer than 100 mesh.