• The Korean Journal of Malacology
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• v.26 no.3
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• pp.235-244
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• 2010

Ultrastructural characteristics of the testis and spermatogenesis of Crassostrea gigas were investigated by Transmission and Scanning Electron microscope observations. The testis is a diffuse organ consisting of branching acini containing differentiating germ cells in a variety of stages. The acinus is surrounded by an intermitent layer of myoepithelial cells andis divided into subcompartments that are partially separated by pleomorphic accessory cells which remain in close contact with germ cells until late stages of development. these accessory cells contain a large quantity of glycogen particles and lipid droplets in the cytoplasm. Therefore, it is assumed that they are involved in the supplying of the nutrients for germ cell development, while any phenomena associated with phagocytosis of undischarged, residual sperms by lysosomes could be find in the cytoplasm of the accessory cells. The morphology of the spermatozoon has a primitive type and is similar to those of other bivalves. Mature spermatozoa consist of broad, cap-shaped acrosomal vesicle, subacrosomal material (containing axial rod embedded in a granular matrix), a oval nucleus showing deeply invaginated anteriorly, two triplet substructure centrioles surrounded by four spherical mitochondria, and satelite fibres appear to the distal centriole and plasma membrane. Spermatozoa of C. gigas resemble to those of other investigated ostreids. In particular, the anterior region of the acrosomal vesicle is transversely banded. It is assumed that differences in this acrosomal substructure are associated with the inability of fertilization between the genus Crassostrea and other genus species in Ostreidae. Therefore, we can use sperm morphology in the resolution of taxonomic relationships within the Ostreidea. The spermatozoon is approximately $42-47{\mu}m$ in length including an oval sperm nucleus (about $0.91{\mu}m$ in length), an acrosome (about $0.42{\mu}m$ in length) and tail flagellum ($40-45{\mu}m$). The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9 + 2 structure. These morphological charateristics of acrosomal vesicle belong to the family Ostreidae in the subclass Pteriomorphia.

• Proceedings of the Ginseng society Conference
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• 2002.10a
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• pp.502-508
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• 2002

The strains of Panax ginseng C.A. Mey., P. quinquefolius L. and selected strains P. ginseng-B, P.ginseng-A, P. quinquefolius-C were investigated. Activities of SOD, catalase and peroxydase were determined by methods of Fridovich et al. (1979), Komov et al.(1975), Bovaird et al.(1982) respectively. Activities of SOD, catalase, peroxydase were investigated every day 5 in cycle of cultivation. For P. ginseng it was the 35 days, P. quinquefolius the 70 days, P. quinquefolius-C 90 days. P. ginseng-B 90 days, P. ginseng-A 60 days. The P. quinquefolius, P. quinquefolius-C, P. ginseng-B had clear differentiation and developed tracheid elements, which are absent in strain of P. ginseng. The peaks of protein content for P. ginseng (4.5 units/g) and for P. quinquefolius (3.5 units/g) were on day 10 and remained unchanged till the last cultivation. The strain P. ginseng-A had two peaks of protein content (2.5 mg/g) on day 15 and on day 30. For P. ginseng-B strain these peaks were on day 5 and day 40 (3.5 mg/g). Peroxydase activity peak (60 units/g) in P. ginseng strain was on day 10. This activity in P. ginseng-B had two peaks on day 15 and day 35 and reached 95 units/g , increasing to 150 units/g to day 80. In strain of P. ginseng-A was only one maximum of this activity -130 units/g on day 45. In P. quinquefolius peroxydase activity was 103 units/g on day 40, increasing to 135 units/g to day 90. For P. quinquefolius-C this activity peak was 136 units/g on day 60. Peroxydase activities for the upper and lower layers of biomass was different and varied considerably from 28-35 units/g in lower to 270-290 units/g for upper layer. The SOD activity had two peaks in P. ginseng strain the 80 units/g and the 70 units/g on day 20 and day 35 respectively. Activity of SOD in P. quinquefolius strain reached 53 units/g on day 40 and increased up to 83 units/g to day 60.The similar increase of SOD activity was marked for P. ginseng-B to 85 units/g on day 90. In P. ginseng strain the 6 molecular isoforms SOD was defined. One of them with RfO,6 was determined in all days of cycle, three other (Rf-0.43; 0.54;0.80) only on day 10 and day 20. The isoform of SOD with Rf-0,29 was detected only on day 10 and with Rf-0,35 only on day 35. The catalase activity decreased in all strains to the last days of cultivation. The changes of SOD, catalase and peroxydase activities reflect the differences between the strains of Panax ginseng and Panax quinquefolius and their selected forms. The correlation between maximum life span of strains and activities of their antioxydant enzymes were detected.

• Nuclear Engineering and Technology
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• v.49 no.5
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• pp.1044-1062
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• 2017

The construction project of the Kijang research reactor (KJRR), which is the second research reactor in Korea, has been launched. The KJRR was designed to use, for the first time, U-Mo fuel. Plate-type U-7 wt.% Mo/Al-5 wt.% Si, referred to as U-7Mo/Ale5Si, dispersion fuel with a uranium loading of $8.0gU/cm^3$, was selected to achieve higher fuel efficiency and performance than are possible when using $U_3Si_2/Al$ dispersion fuel. To qualify the U-Mo fuel in terms of plate geometry, the first miniplates [HANARO Miniplate (HAMP-1)], containing U-7Mo/Al-5Si dispersion fuel ($8gU/cm^3$), were fabricated at the Korea Atomic Energy Research Institute and recently irradiated at HANARO. The PIE (Post-irradiation Examination) results of the HAMP-1 irradiation test were analyzed in depth in order to verify the safe in-pile performance of the U-7Mo/Al-5Si dispersion fuel under the KJRR irradiation conditions. Nondestructive analyses included visual inspection, gamma spectrometric mapping, and two-dimensional measurements of the plate thickness and oxide thickness. Destructive PIE work was also carried out, focusing on characterization of the microstructural behavior using optical microscopy and scanning electron microscopy. Electron probe microanalysis was also used to measure the elemental concentrations in the interaction layer formed between the U-Mo kernels and the matrix. A blistering threshold test and a bending test were performed on the irradiated HAMP-1 miniplates that were saved from the destructive tests. Swelling evaluation of the U-Mo fuel was also conducted using two methods: plate thickness measurement and meat thickness measurement.

• Food Science and Preservation
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• v.11 no.1
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• pp.63-70
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• 2004

The antimicrobial substances from Rhodiola sachalinensis were extncted, isolated and identified. The highest level of antimicrobial activity and its yield were obtained in methanol extract. The minimum inhibition concentrations of the methanol extract were 500 $\mu\textrm{g}$mL on agar plate and 100 $\mu\textrm{g}$mL in broth media for four gram positive and four gram negative microbials. The methanol extract was fractionated by n-hexane, chloroform, ethyl ether, ethyl acetate, and butanol, orderly. The separate was developed on the TLC plate with different solvent system ratio of chloroform and methanol. Nine substances were isolated from chloroform and methanol mixture(9:1, v/v). Among them, three isolates showed antimicrobial activity. Three substances separated by HPLC were identified by GC/MS(EI) spectrum and $^1$H, /sup13/C-NMR spectrum. They were gallic acid, (-)-epicatechin and kaempferol. The antimicrobial activities of each substances were shown gallic acid, (-)-epicatechin, kaempferol orderly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.319-325
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• 2018

The use of 3D printing (Additive Manufacturing) technology has expanded from initial model production to the mass production of parts in the industrial field based on the continuous research and development of materials and process technology. As a representative polymer material for 3D printing, the polyamide-based material, which is one of the high-strength engineering plastics, is used mainly for manufacturing parts for automobiles because of its light weight and durability. In this study, the specimens were fabricated using Selective Laser Sintering, which has excellent mechanical properties, and the flexural characteristics were analyzed according to the temperature of the two types of polyamide 12 and glass bead reinforced PA12 materials. The test specimens were prepared in the directions of $0^{\circ}$, $45^{\circ}$, and $90^{\circ}$ based on the work platform, and then subjected to a flexural test in three test temperature environments of $-25^{\circ}C$, $25^{\circ}C$, and $60^{\circ}C$. As a result, PA12 had the maximum flexural strength in the direction of $90^{\circ}$ at $-25^{\circ}C$ and $0^{\circ}$ at $25^{\circ}C$ and $60^{\circ}C$. The glass bead-reinforced PA12 exhibited maximum flexural strength values at all test temperatures in the $0^{\circ}$ fabrication direction. The tendency of the flexural strength changes of the two materials was different due to the influence of the plane direction of the lamination layer depending on the type of stress generated in the bending test.

• Journal of Life Science
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• v.29 no.1
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• pp.90-96
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• 2019

The objective of this study was to evaluate the potential of Diospyros malabarica stem extract, a natural materials, in oral health material. With this aim in mind, thin layer chromatography (TLC), TLC-bioautography, high-performance liquid chromatography (HPLC), electrospray ionization-mass spectrometry (ESI-MS), scanning electron microscopy (SEM), and real-time qPCR were performed. The antibacterial activity of D. malabarica stem extract against Streptococcus mutans KCTC3065 was confirmed in an n-hexane fraction with low polarity. The molecular weight of the antibacterial compound was estimated to be 188 by ESI-MS analysis. The inhibitory effects of the extract on biofilm formation and gene expression related to biofilm formation of S. mutans were determined by SEM and real-time PCR analysis. The extract inhibited the formation of S. mutans biofilms at D. malabarica stem extract concentrations of 1 mg/ml, as shown by SEM. The real-time PCR analysis showed that the expression of the gtfC gene, which is associated with biofilm formation, was significantly decreased in a dose-dependent manner. Based on the above results, it can be concluded that D. malabarica stem extracts, a natural materials, can be used in oral health products to suppress the formation of biofilms by inhibiting tooth adhesion of S. mutans, a causative agent of dental caries.

• Journal of Digital Convergence
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• v.17 no.1
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• pp.209-217
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• 2019

In this paper, the purpose of this paper is to lay the foundation for the search system by using and building an online search engine suitable for the search domain and enabling search, conversion, integration and sharing of information. It is to use the ontology to infer hierarchical relationships, deduce objects based on that layer, and extract attributes to search areas that are relevant to the data that the user wants. In order to search for information in this way, the information search system was implemented by entering key words related to 'qualifications'. The implemented system arranged the meaning and relationship of each attribute online so that the general public can search information quickly, easily, and accurately. In addition, the implementation results were compared with two different search engines. Comparable search engines are Naver and Daum, the two major search engines. The search engine of this study, which was built using an ontology suitable for the search domain to perform searches using the semantic web, was evaluated to have excellent results. However, it is thought that a more formalized online location is necessary to increase the accuracy and reliability of search engines and to include more comprehensive categories of search terms.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.1
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• pp.15-28
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• 2019

In accordance with the decommissioning plan for the Kori Unit 1 NPP, the reactor coolant system will be chemically decontaminated as soon as possible after permanent shutdown. This study developed the chemical decontamination process though the development project of decontamination technology of reactor coolant system and dismantled equipment for NPP decommissioning, which has been carried out since 2014. In this study, Oxidation/reduction process was conducted using system decontamination process development equipment of lab scale and was divided into unit and continuous processes. The optimal process time was derived from the unit process, and decontamination agent and the number of process were derived through the continuous processes. Through the unit process, the oxidation process took 5 hours and the reduction process took 4 hours. As optimum decontamination agent, the oxidizing agent was $200mg{\cdot}L^{-1}$ Permanganic acid + $200mg{\cdot}L^{-1}$ Nitric acid and the reducing agent was $2000mg{\cdot}L^{-1}$ Oxalic acid. In the case of the number of processes, all oxide films were removed during the two-cycle chemical decontamination process of STS304 and SA508. In the case of Alloy600, all oxide films were removed when chemical decontamination was performed for three cycles or more.

• Korean Journal of Plant Resources
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• v.34 no.5
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• pp.491-501
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• 2021

This study was carried out to investigate the occurrence of seedlings of Korean fir (Abies koreana) in Korean fir forest located on the eastern slope of Mt. Halla National Park. Between June and August in 2016, the systematic sampling method was applied to 125 plots of 5 m × 5 m quadrats and field survey was came out to measure the characteristics of sites and understory vegetation. Correlation analysis was applied to the variables quantified from the data collected. Total number of flora found at the study site is 31 in families, 44 in genera, and 56 in species. The main lower layer vegetation was investigated such as Jeju dwarf bamboo, Toothed club moss (Lycopodium serratum), Pacific fir moss (Lycopodium chinense), Climbing hydrangea (Hydrangea petiolaris) etc. Among these plant species, the vegetation which had a high positive correlation with the frequency and the coverage of seedlings of Korean fir were Jeju dwarf bamboo, Toothed club moss and Pacific fir moss.

• Journal of Soil and Groundwater Environment
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• v.26 no.5
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• pp.20-28
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• 2021

Perfluorinated compounds(PFCs), an emerging environmental pollutant, are environmentally persistent and bioaccumulative organic compounds that possess a toxic impact on human health and ecosystems. PFCs are distributed widely in environment media including groundwater, surface water, soil and sediment. PFCs in contaminated solid can potentially leach into groundwater. Therefore, understanding PFCs partitioning between the aqueous phase and solid phase is important for the determination of their fate and transport in the environment. In this study, the sorption equilibrium batch and kinetic experiment of PFCs were carried out to estimated the sorption coefficient(K_d) and the fraction between aqueous-solid phase partition, respectively. Sorption branches of the PFDA(Perfluoro-n-decanoic acid), PFNA(Perfluoro-n-nonanoic acid), PFOA(Perfluoro-n-octanoic acid), PFOS(Perfluoro-1-octane sulfonic acid) and PFHxS(Perfluoro-1-hexane sulfonic acid) isotherms were nearly linear, and the estimated K_d was as follow: PFDA(1.50) > PFOS(1.49) > PFNA(0.81) > PFHxS(0.45) > PFOA(0.39). The sorption kinetics of PFDA, PFNA, PFOA, PFOS and PFHxS onto soil were described by a biexponential adsorption model, suggesting that a fast transport into the surface layer of soil, followed by two-step diffusion transport into the internal water and/or organic matter of soil. Shorter times(<20hr) were required to achieve equilibrium and fraction for adsorption on solid(F₁, F₂) increased with perfluorinated carbon chain length and sulfonate compounds in this study. Overall, our results suggested that not only the perfluorocarbon chain length, but also the terminal functional groups are important contributors to electrostatic and hydrophobic interactions between PFCs and soils, and organic matter in soils significantly affects adsorption maximum capacity than kinetic rate.