• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.4
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• pp.229-233
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• 2015

In this paper, in order to develop outstanding Pb-free piezoelectric composition ceramics, the $(Na_{0.525}K_{0.443}Li_{0.037})(Nb_{0.883}Sb_{0.08}Ta_{0.037})O_3+0.3wt%Bi_2O_3+0.4wt%Fe_2O_3+xwt%CuO$ (x= 0~0.8 wt%)(abbreviated as NKL-NST) lead-free piezoelectric ceramics have been synthesized using the ordinary solid state reaction method. The effects of CuO-doping on the structure and electrical properties of the NKL-NST ceramics were systematically studied. The results show that the ceramics exhibit a pure perovskite structure with orthorhombic phase at room temperature, and secondary phase was found in the ceramics. The 0.4 wt%CuO added ceramics sintered at $950^{\circ}C$ showed the optimum properties of piezoelectric constant($d_{33}$), planar piezoelectric coupling coefficient(kp) and mechanical quality factor(Qm) : $d_{33}=213$[pC/N], kp= 0.43, Qm= 423,respectively.

• Corrosion Science and Technology
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• v.9 no.6
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• pp.247-253
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• 2010

The characteristics of selective oxidation prior to hot-dip galvanizing with the annealing atmosphere dew point and chemical composition in dual-phase steels and their effect on the inhibition layer formation relevant to coating adhesion have been studied using a combination of electron microscopic and surface analytical techniques. The annealed and also galvanized samples of 3 kinds of Si/Mn ratios with varied amounts of Si addition were prepared by galvanizing simulator. The dew point was controlled at soaking temperature $800^{\circ}C$ in 15%$H_2$ -85%$N_2$ atmosphere. It was shown that good adhesion factors were mainly uniformity of oxide particle distribution of low number density and low Si/Mn ratio prior to hot-dip galvanizing. Their effect was the greatly reduced coating bare spots and the formation of uniform inhibition layer leading to good adhesion of Zn overlay. The mechanism of good adhesion is suggested by two processes: the formation of inhibition layer on the oxide free surface uncovered with no $SiO_2$-containing particles in particular, and the inhibition layer bridging of oxide particles. The growth of inhibition layer was enhanced markedly by the delayed reaction of Fe and Al with the increase of Si/Mn ratio.

• Corrosion Science and Technology
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• v.23 no.4
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• pp.278-282
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• 2024

Recently, hot rolled galvanized steel is widely used in automotive parts. As the paradigm of the automotive market has changed from fossil fuel vehicle to electric vehicle, the automotive industry needs more high-strength steels to reduce weights of automobiles. However, because high-strength steel contains high solute carbon, it is expected to have a risk of stretcher-strain on the surface due to dislocation trapping by solute [C] and [N]. Generally, galvanized steel is supposed to pass through a furnace around the temperature of Zinc pot to increase material temperature. Otherwise, the inhibition layer could not be formed. However, solute carbon and nitrogen are volatile enough to move around the furnace temperature. Moreover, the ratio of ferrite phase and precipitated Fe3C can be variable, resulting in yield point elongation related to the stretcher strain. Furthermore, the quality of the galvanized surface can be affected by a high temperature of the furnace. Although a relatively hot rolled galvanizing line furnace has a lower temperature than an annealing line furnace, it can affect various quality aspects. In other words, this paper aims to determine how these phenomena appear concerning furnace temperature.

• Korean Journal of Microbiology
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• v.41 no.1
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• pp.81-86
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• 2005

One of the endoglucanases, F-I-III, was purified from the culture filtrate of T. sp. C-4 through procedures including chromatography on Sephacryl S-200, DEAE-Sepharose A-50, and Chromatofocusing on Mono-P (FPLC). The molecular weight of the enzyme was determined to be about 56,000 Da by SDS-PAGE, and pI of 4.9 by analytical isoelectric focusing. F-I-III showed the highest enzyme activity at $55^{\circ}C$, and the pH optimum of the enzyme was 5.0. There was no loss of activity when the enzyme was incubated at $50^{\circ}C$ for 24 hours. The specific activity of the enzyme F-I-III toward the CMC was 315.4 U/mg. The Km value for $PNPG_2$ of F-I-III was 2.69 mM. N-terminal sequence of F-I-III was analyzed to be QPGTSTPEVHPKKLTTYK. It showed $95\%$ of homology to that of EGI from T. reesei. The presence of some metal ions (1 mM) had only a little effect on CMCase activity. The treatment of the reducing agents resulted in the increase of endoglucanase activity.

• Archives of Pharmacal Research
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• v.18 no.2
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• pp.90-99
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• 1995

The effect of protein kinase C inhibitors, sturosporine and 1-(5-isoquinolinyl sulfonyl)-2-methyl piperazine(H7) on in vitro differentiation of erythroid progenitor cells which were isolated from spleens of mice infected with the anemia-inducing strain of Friend virus were examined. Erythropoietin-mediated differentitation of erythroid progenitor cells, as determined by the incorporation of $^{59}Fe$ into protoporphyrin, was inhibited by staurosporine and H7 in a concentration -dependent manner. Scatchard analysis of the $^3H-phorbol-12$, 13-dibutyrate binding to erythroid progenitor cells revealed that at the high affinity sites the dissociation constant was 22nM and the maximum number of $^3H-phorbol-12$, 13-dibutyrate binding to erythroid progenitor cells revealed that at the high affinity sites the dissociation constant was 22nM and the maximum number of $^3H-phorbol-12$, 13-dibutyrate binding sites per cell was approximately $3.7\times10^5$. Cytosonic protein kinase C was isolated from erthroid progenitor cells and then purified by sequential column chromatogrphy. Two isoforms of protein kinase C were found. Photoaffinity labeling of the purified protein kinase C samples with $^3H-phorbol-12$12-myristate 13-acetate followed by analysis of SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and autofluorography showed radiolabeled 82-KDa pepticles. Rediolabeling of the 82-KDa peptides with $^3H-phorbol-12$myristate 13-acete was almost completely blocked by excess unlabeled phorbol 12-myristate 13-acetate was almost 12-muristate 13-acetate-promoted phosphorylation with the puyrified protein kinase C samples showed that the phosphorylation of 82-KDa peptides was increased as the concentration of phorbol 12-myristate 13-acetate was increased from $10^{-8}M{\;}to{\;}10^{-4}$M. In light of the findings that erythroid progenitor cells possessed an abundance of protein kinase C and that stauroporine and H7 inhibited erythroid differentiation, it seemed likely that protein kinase C would play a role in the erythroid progenitor cell development.

• Horticultural Science & Technology
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• v.29 no.3
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• pp.195-200
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• 2011

The growth, yield and quality of Sedum sarmentosum between soil and hydroponic cultivation were compared to produce high-quality shoots in summer season. The plants were collected from four places in Korea and cultivated in a plastic film house with 50% shading. A 1:1:1 mixtures of sand, upland soil and substrate (N-P-K: 330-220-400 $mg{\cdot}L^{-1}$) was used for soil cultivation, and a nutrient film technique (NFT) with Yamazaki-lettuce nutrient solution used for hydroponics. After 30 days of cultivation, plant height ranged from 18.4 to 21.8 cm and showed no significant difference between soil and hydroponic cultivation. Number of shoot, leaf length, leaf width, number of leaf, fresh weight, and dry weight significantly increased in hydroponics compared to those in soil cultivation. Fresh and dry weights in hydroponics were greater in 'Gunsan' and 'Wando' collections than those in other collections. Stem diameter and compression-force significantly increased in soil cultivation rather than hydroponics with significant differences among collections. However there were no significant differences in shoot bitterness and vitamin C content between cultivation methods or among the collections. Most mineral contents except Fe in hydroponics were higher than those in soil cultivation. K, Na, Zn contents in hydroponics were over 2 times higher than those in soil cultivation.

• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.93-103
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• 2011

Precipitation behavior of high-nitrogen duplex Fe-24Cr-7Mn-4Ni-4Mo-0.43N stainless steel aged at $850^{\circ}C$ was investigated using scanning transmission electron microscopy. Based on the analyses of selected area diffraction patterns, four kinds of precipitates (intermetallic sigma (${\sigma}$) and chi (${\chi}$), $Cr_2N$ and secondary austenite) were identified. At the ferrite/austenite phase boundary, the ${\sigma}$ phase and secondary austenite were formed via ${\alpha}{\rightarrow}{\gamma}+{\sigma}$ eutectoid reaction. The precipitation of $Cr_2N$ occurred at the austenite grain boundary as well as the interior of the ferrite. The intermetallic ${\chi}$ phase also formed within the ferrite and showed a cube-cube orientation relationship with the ferrite. Further aging produced a lamellar structure composed of $Cr_2N$ and austenite along the ferrite/austenite boundary and enhanced the precipitation of the ${\chi}$ phase. The crystallographic features of the precipitates were also examined in terms of the orientation relationship with the austenite or ferrite matrix.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.50 no.1
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• pp.13-26
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• 2024

Objectives: The aim of this study was to perform a comparative analysis of the ultrastructural and chemical composition of sialoliths, tonsilloliths, and antroliths and to describe their growth pattern. Materials and Methods: We obtained 19 specimens from 18 patients and classified the specimens into three groups: sialolith (A), tonsillolith (B), and antrolith (C). The peripheral, middle, and core regions of the specimens were examined in detail by histology, micro-computed tomography (micro-CT), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and transmission electron microscopy (TEM). Results: In the micro-CT, group A showed alternating radiodense and radiolucent layers, while group B had a homogeneous structure. Group C specimens revealed a compact homogeneous structure. Histopathologically, group A showed a laminated, teardrop-shaped, globular structure. Group B demonstrated degrees of immature calcification of organic and inorganic materials. In group C, the lesion was not encapsulated and showed a homogeneous lamellar bone structure. SEM revealed that group A showed distinct three layers: a peripheral multilayer zone, intermediate compact zone, and the central nidus area; groups B and C did not show these layers. The main elemental components of sialoliths were O, C, Ca, N, Cu, P, Zn, Si, Zr, F, Na, and Mg. In group B, a small amount of Fe was found in the peripheral region. Group C had a shorter component list: Ca, C, O, P, F, N, Si, Na, and Mg. TEM analysis of group A showed globular structures undergoing intra-vesicular calcification. In group B, bacteria were present in the middle layer. In the outer layer of the group C antrolith, an osteoblastic rimming was observed. Conclusion: Sialoliths had distinct three layers: a peripheral multilayer zone, an intermediate compact zone and the central nidus area, while the tonsillolith and antrolith specimens lacked distinct layers and a core.

• Korean Journal of Microbiology
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• v.33 no.1
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• pp.15-21
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• 1997

We studied the characteristics of extracellular autolysins from Moraxella sp. CK-1 which has been known to lyse the cyanobacterial cell walls. This bacterium excreted autolysins from the early exponential growth phase. These enzymes showed optimal action condition of 60-$70^{\circ}C$ and pH 9.0. Whereas $Na^{+}$, $K^{+}$ and $Li^{+}$ ions exhibited positive effect on the enzyme activity, $Ba^{2+}$, $Mg^{2+}$, $Ca^{2+}$ and $Mn^{2+}$ ions exhibited negative effect. Especially, $Fe^{2+}$ and $Cu^{2+}$ ions almost completely suppressed the activity. Four extracellular autolysins of 30, 32, 38 and 41 kDa were detected in renaturing SOS-PAGE gel containing 0.2% heat-killed Micrococcus luteus cells as substrate. Among these 4 autolysins, 2 enzymes of 32 and 41 kDa distributed in the culture medium throughout the experimental time, but the 38 kOa enzyme diminished and 30 kOa began to appear at mid-exponential growth phase. When SOS-insoluble peptidoglycan of M. luteus was treated with the autolysins of Moraxella sp. CK-l, the concentration of free amino groups in reaction mixture increased. This indicates that the autolysins are N-acetylmuramyl-L-alanine amidase or endopeptidase.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.4
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• pp.434-442
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• 1988

This study has been made to investigate the influences of organic matter on the soil composition, nitrogen fixing organism, soil enzyme activity and nitrogen fixing activity in the paddy rice rhizosphere when rice and barley straw were applied. The results are summarized as follows: 1. The pH in the submerged soil was increased from ear formation stage to harvesting. 2. In the rhizosphere, $Fe^{{+}{+}}$ content was decreased according to the growing stage, while increased in the nonrhizosphere. 3. In the initial stage, rhizosphere was higher than nonrhizosphere but in the late stage nonrhizosphere was higher than rhizosphere on the $NH_4-N$ content. 4. In the submerged soil, rhizosphere was higher than nonrhizosphere, on the concentration of glucose and pentose. 5. Changes of the number of nitrogen fixing organism in whole soil was not high. 6. Generally, rhizosphere was higher than nonrhizosphere on the soil enzyme activity such as phosphatase, ${\beta}$-glucosidase, and protease. 7. Acetylene-reducing activity was the highest in the tillering stage, and rhizosphere, Samgang (high-yielding variety) were higher than nonrhizosphere. Dongjin (general variety) respectively. 8. In the submerged soil applied barley straw, acetylene-reducing activity was slightly higher than rice straw in the initial stage.