• The Journal of Korean Academy of Prosthodontics
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• v.30 no.2
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• pp.135-154
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• 1992

This study was performed to analyze bond strength, the alterations of the interfaces between metal films which are populary used and considered to contribute to the chemical reaction with porcelain, according to constant ion- beam- mixing, and the relation between interfacial chemical reactions and bond strength in metal/porcelain specimens. For this study, three seperate metals : selected-gold, indium and tin were chosen ; each to be bonded to a seperate body porcelain. Bonding occurs when the metal is deposited to the body porcelain using a vacuum evaporator. The vacuum evaporator used $10^{-5}\sim10^{-6}$ Torr vacuum states for the evaporation of various metals (Au, Sn, In). Ion-beam-mixing of the porcelain/metal interfaces caused reactions when the Ar+ was implanted into thin films using a 80 KeV accelerator. These ion-beam-mixed specimens were then compared with an unmixed control group. An analysis of bond strength and ionic changes between the the metal and porcelain was performed by electron spectroscopy of chemical analysis (ESCA) and scratch test. The finding led to the following conclusions : 1. Light microscopic views of the scratch test : The ion-beam-mixed Au/porcelain specimen showed narrower scratched streams than the unmixed specimen. However, the Sn/porcelain, In/porcelain specimens showed no differences in the two conditions. 2. Acoustic emissions in scratch tests : The ion-mixed Au/porcelain, In/porcelain specimens showed signals closer to the metal/porcelain interfaces than unmixed specimens. Conversely, the ion-mixed Sn/porcelain specimen showed more critical signals in superficial portions than unmixed specimens. 3. After ion- beam-mixing, the Au/porcelain specimen showed apparently increased bond strength, and the In/porcelain specimen showed very slightly increased bond strength. However, the Sn/porcelain specimen showed no differences between ion mixed specimen and the unmixed one. 4. ESCA analysis : The ion-beam-mixed Au/porcelain specimen showed a higher peak separated value (4.3eV) than that of the unmixed specimen(3.65eV), the ion-beam-mixed In/porcelain specimen showed a higher peak separated value (9.43eV) than that of the unmixed specimen(7.6eV) and the ion-beam-mixed Sn/porcelain specimen showed a higher peak separated value (8.79eV) than that of the unmixed specimen(8.5eV). 5. Interfacial changes were observed in the ion-mixed Au/porcelain, In/porcelain and Sn/porcelain specimens. Especially, significant interfacial changes were measured in the ion- mixed Sn/porcelain specimen. Tin dioxide(SnO2) and a combination of pure tin and tin dioxide (Sn+SnO2) were produced. 6. In the Au/porcelain specimen, the interfacial chemical reaction showed increased bond strength between gold and porcelain substrate. But, in the In/porcelain, Sn/porcelain specimens, interfacial chemical reactions did not affected the bond strength between metal and porcelain substrate. Especially, bonding strength on the ion mixed Sn/porcelain specimen showed the least amount of difference.

• Advances in Traditional Medicine
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• v.1 no.1
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• pp.8-27
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• 2000

Components of extracellular matrix and the matrix-degrading enzymes are some of the key regulators of tumor metastasis and angiogenesis. Hyaluronic acid (HA), a matrix glycosaminoglycan, is known to promote tumor adhesion and migration, and its small fragments are angiogenic. Until now, we have compared levels of hyaluronidase, an enzyme that degrade HA, in normal adult prostate, benign prostate hyperplasia and prostate cancer tissues and in conditioned media from epithelial explant cultures, using a substrate (HA)-gel assay and ELISA-like assay (Kim et al., unpublished results). The present review described an overall characterization of hyaluronidases and its application to human diseases. The hyaluronidases are a family of enzymes that have, until recently, deed thorough explication. The substrate for these enzymes, hyaluronan, is becoming increasingly important, recognized now as a major participant in basic processes such as cell motility, wound healing, embryogenesis, and implicated in cancer progression. And in those lower life forms that torment human beings, hyaluronidase is associated with mechanisms of entry and spread, e.g. as a virulence factor for bacteria, for tissue dissection in gas gangrene, as a means of treponema spread in syphilis, and for penetration of skin and gut by nematode parasites. Hyaluronidase also comprises a component of the venom of a wide variety of organisms, including bees, wasps, hornets, spiders, scorpions, sh, snakes and lizards. Of particular interest is the homology between some of these venom hyaluronidases and the enzyme found in the plasma membrane of mammalian spermatozoa, attesting to the ancient nature of the conserved sequence, a 36% identity in a 300 amino acid stretch of the enzyme protein. Clearly, hyaluronidase is of biological interest, being involved in the pathophysiology of so many important' human disorders. Greater effort should be made in studying this family of enzymes that have, until recently, been overlooked. Also, oriental medical application of the hyaluronidase will be discussed with respect to inhibition and suppression of inflammation and malignacy.

• Journal of Mushroom
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• v.15 no.1
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• pp.25-30
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• 2017

'Baekseung', a new variety of Flammulina velutipes, was bred by mating two monokaryotic strains isolated from KMCC 4210 and KMCC 4216 in the Mushroom Research Division, Baekseung ARES in 2016. The Baekseung and Uri1ho strains showed fast mycelial growth and mycelial density on malt extract agar media after 7 days of incubation. The spawn running period on the sawdust substrate required a cultivation period and temperature of 30 days and $25^{\circ}C$, respectively, for primordia formation where in fruiting body development occurred from $11{\pm}1days$ at $14^{\circ}C$ and $14{\pm}1days$ at $7^{\circ}C$. The length of the pilei and stipes of the Baekseung harvested in optimal stag were $11.3{\pm}0.4$ and $89.2{\pm}7.1mm$, respectively, whereas the values for Uri1ho were $10.7{\pm}1.0$ and $91.3{\pm}20.8mm$, respectively. The yield of the Baekseung and Uri1ho strain grown on the sawdust substrate was $153.7{\pm}12.5$ and $139.8{\pm}17.8g$, respectively, per 850 ml in bottle cultivation. The inferred tree exhibited a phylogenetic relationship between the Korean white fruiting body strains of Baekseung, Uri1ho and Fv-14-a-38, Fv-14-a-51, and the Japanese white fruiting body-forming strains of KMCC 4226, and these were confirmed to be genetically related.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.249-249
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• 2013

Surface-enhanced Raman spectroscopy (SERS) is a sensitive approach to detect and to identify a variety of molecules. To enhance the Raman signal, optimization of the gap between nanostructures is quite important. One-dimensional materials such as nanowires, nanotubes, and nanograsses have great potential to be used in SERS due to their unique sizes and shape dependent characteristics. In this study we investigate a simple way to fabricate SERS substrates based on randomly grown copper oxide (CuO) nanowires. CuO nanograss is fabricated on pre-cleaned Cu foils. Cu oxidized in an ammonium ambient solution of 2.5 M NaOH and 0.1 M $(NH_4)_2S_2O_8$ at $4^{\circ}C$ for 10, 30, and 60 minutes. Then, Cu(OH)2 nanostructures are formed and dried at $180^{\circ}C$ for 2 h. With the drying process, the Cu(OH)2 nanostructure is transformed to CuO nanograss by dehydration reaction. CuO nanograss are grown randomly on Cu foil with the average length of 10 ${\mu}m$ and the average diameter of a 100 nm. CuO nanograsses are covered by Ag with various thicknesses from 10 to 30 nm using a thermal evaporator. Then, we immerse uncoated and Ag coated CuO nanowire samples of various oxidation times in a 0.001M methanol-based 4-mercaptopyridine (4-Mpy) in order to evaluate SERS enhancement. Raman shift and SERS enhancement are measured using a Raman spectrometer (Horiba, LabRAM ARAMIS Spectrometer) with the laser wavelength of 532 nm. Raman scattering is believed to be enhanced by the interaction between CuO nanograss and Ag island film. The gaps between Ag covered CuO nanograsses are diverse from <10 nm at the bottom to ~200 nm at the top of nanograsses. SERS signal are improved where the gaps are minimized to near 10s of nanometers. There are many spots that provide sufficiently narrow gap between the structures on randomly grown CuO nanograss surface. Then we may find optimal enhancement of Raman signal using the mapping data of average results. Fabrication of CuO nanograss based on a solution method is relatively simple and fast so this result can potentially provide a path toward cost effective fabrication of SERS substrate for sensing applications.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1211-1215
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• 1999

Fluorinated amorphous carbon (a-C:F) films were prepared by an electron cyclotron resonance chemical vapor deposition (ECRCVD) system using a gas mixture of $C_2F_6$ and $CH_4$ over a range of deposition temperature (room temperature ~ 300$^{\circ}C$). 500$^{\AA}C$ thick DLC films were pre-deposited on Si substrate to improve the strength between substrate and a-C:F film. The chemical bonding structure, chemical composition, surface roughness and dielectric constant of a-C:F films deposited by varying the deposition temperature were studied with a variety of techniques, such as Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), atomic force microscopy (AFM) and capacitance-voltage(C-V) measurement. Both deposition rate and fluorine content decreased linearly with increasing deposition temperature. As the deposition temperature increased from room temperature to 300$^{\circ}C$, the fluorine concentration decreased from 53.9at.% down to 41.0at.%. The dielectric constant increased from 2.45 to 2.71 with increasing the deposition temperature from room temperature to 300$^{\circ}C$. The film shrinkage was reduced with increasing deposition temperature. This results ascribed by the increased crosslinking in the films at the higher deposition temperature.

• Journal of the Korean institute of surface engineering
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• v.56 no.3
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• pp.192-200
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• 2023

Graphene, a two-dimensional material, has shown great potential in a variety of applications including microelectronics, optoelectronics, and graphene-based batteries due to its excellent electronic conductivity. However, the production of large-area, high-quality graphene remains a challenge. In this study, we investigated graphene growth on electrolytic copper foil using thermochemical vapor deposition (TCVD) to achieve a similar level of quality to the cold-rolled copper substrate at a lower cost. The combined effects of pre-annealing time, graphenized temperature, and partial pressure of hydrogen on graphene coverage and domain size were analyzed and correlated with the roughness and crystallographic texture of the copper substrate. Our results show that controlling the crystallographic texture of copper substrates through annealing is an effective way to improve graphene growth properties, which will potentially lead to more efficient and cost-effective graphene production. At a hydrogen partial pressure that is disadvantageous in graphene growth, electrolytic copper had an average size of 8.039 ㎛², whereas rolled copper had a size of 19.092 ㎛², which was a large difference of 42.1% compared to rolled copper. However, at the proper hydrogen partial pressure, electrolytic copper had an average size of 30.279 ㎛² and rolled copper had a size of 32.378 ㎛², showing a much smaller difference of 93.5% than before. This observation suggests this potentially leads the way for more efficient and cost-effective graphene production.

• Journal of Mushroom
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• v.22 no.2
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• pp.67-72
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• 2024

In this study, we investigated the microbial community of oyster mushrooms at different growth stages at the species level. Gram-positive bacteria were predominant in the presterilized medium. On the other hand, Gram-negative bacteria were predominant in the culture-completed medium, post-harvest medium, and fruiting bodies. In addition, Pseudomonas tolaasii, which is known to cause disease in mushrooms, was confirmed in the cultured medium, post-harvest medium, and fruiting bodies, and it was determined that the mycelium culture stage was contaminated, and the reason why no disease occurred was Sphingobacterium psychroaquaticum. It was confirmed that this was because the growth of Pseudomonas tolaasii was suppressed by producing a component called tolacin. As a result of confirming the diversity of microorganisms, it was confirmed that the presterilization medium contains a variety of microorganisms compared to other growth stages, and the diversity decreases in the order of culture completion medium, fruiting body, and post-harvest medium. showed a trend. As a result of microbial similarity analysis, it was confirmed that the cultured medium and the post-harvest medium showed similar microbial communities, and in the case of fruiting bodies, there were some similarities but overall differences.

• The Korean Journal of Mycology
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• v.48 no.2
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• pp.95-102
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• 2020

This study was carried out to develop a new method of cultivation of 'Hwadam' a new variety of Lentinula edodes, to improve fruiting body productivity and reduce labor. To determine the optimum filter number for box cultivation, L. edodes were assessed for their cultural characteristics and mushroom yield. During spawn running of L. edodes in the box, the temperature gradually increased to the highest value of 25.8℃, 23.7℃, and 23.0℃ on day 18 for the four filter, two filter, and no treatment groups, respectively. Oxygen concentration displayed an opposite trend to carbon dioxide concentration, reaching the lowest value on day 21. The oxygen concentration progressively increased as more filters were used (5.4%, 8.2%, and 8.9% treatment with no, two, and four filters, respectively. Growth of L, edodes in the box resulted in the highest yield (2,228 g/7kg substrate) and biological efficiency (70.7%) using four filters. The biological efficiency of the four filter treatment was 29.4% higher compared to bag cultivation (41.3%). Further studies are necessary to verify stable productivity of fruiting bodies through repeated cultivation.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.2
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• pp.137-142
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• 2004

In this study, a simple procedure is described for patterning biotin on a glass substrate and then selectively immobilizing proteins of interest onto the biotin-patterned surface. Microcontact printing (CP) was used to generate the micropattern of biotin and to demonstrate the selective immobilization of proteins by using enhanced green fluorescent protein (EGFP) as a model protein, of which the C-terminus was fused to a core streptavidin (cSA) gene of Streptomyces avidinii. Confocal fluorescence microscopy was used to visualize the pattern of the immobilized protein (EGFP-cSA), and surface plasmon resonance was used to characterize biological activity of the immobilized EGFP-cSA. The results suggest that this strategy, which consists of a combination of $\mu$CP and cSA-fused proteins. is an effective way for fabricating biologically active substrates that are suitable for a wide variety of applications. one such being the use in protein-protein assays.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.391-392
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• 2012

Graphene is a perfectly two-dimensional (2D) atomic crystal which consists of sp2 bonded carbon atoms like a honeycomb lattice. With its unique structure, graphene provides outstanding electrical, mechanical, and optical properties, thus enabling wide variety of applications including a strong potential to extend the technology beyond the conventional Si based electronic materials. Currently, the widespread application for electrostatically switchable devices is limited by its characteristic of zero-energy gap and complex process in its synthesis. Several groups have investigated nanoribbon, strained, or nanomeshed graphenes to induce a band gap. Among various techniques to synthesize graphene, chemical vapor deposition (CVD) is suited to make relatively large scale growth of graphene layers. Direct growth of graphene on hexagonal boron nitride (h-BN) using CVD has gained much attention as the atomically smooth surface, relatively small lattice mismatch (~1.7％) of h-BN provides good quality graphene with high mobility. In addition, induced band gap of graphene on h-BN has been demonstrated to a meaningful value about ~0.5 eV.[1] In this paper, we report the synthesis of grpahene / h-BN bilayer in a chemical vapor deposition (CVD) process by controlling the gas flux ratio and deposition rate with temperature. The h-BN (99.99％) substrate, pure Ar as carrier gas, and $CH_4$ are used to grow graphene. The number of graphene layer grown on the h-BN tends to be proportional to growth time and $CH_4$ gas flow rate. Epitaxially grown graphene on h-BN are characterized by scanning electron microscopy, atomic force microscopy, and Raman spectroscopy.