• Journal of the Korean Ceramic Society
• /
• v.39 no.9
• /
• pp.846-850
• /
• 2002

A PMN-PT-BT/Ag composite was prepared by surface modification with MgO sol with hoping to suppress silver's migration during sintering. The mixture of PbO, $N_2O_5,\;TiO_2\;with\;Mg(NO_3)_2$ instead of MgO was ball milled, the solvent was removed and then the dried powders were calcined at 950$^{\circ}C$/1h. The calcined powder were treated with 3.0 mol% $Ag_2O$ and 1.0 wt% MgO sol and calcined at 550$^{\circ}C$/1h. The dielectrics sintered at 1000$^{\circ}C$/4h under a flowing oxygen showed the density of 7.84g/$cm^3$, the room temperature dielectric constant of 18400, the dielectric loss of 2.4%, the specific resistivity of $0.24{\times}10^{12}{\Omega}{\cdot}cm$. It also showed the bending strength of $120.7{\pm}11.26$ MPa and the fracture toughness of $0.87{\pm}0.002\;MPam^{1/2}$ which were comparable to commercial PZT. The microstructure sonsisted of grains of ∼4${\mu}m$. SEM and SIMS analysis showed that Ag grew as ∼1${\mu}m$ and excess MgO as ∼0.5${\mu}m$.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.4A
• /
• pp.565-571
• /
• 2008

Recently, the evaluation technique using NDT (Nondestructive Technique : NDT) is widely utilized because it makes little damage on RC (Reinforced Concrete : RC) structures. The techniques using electromagnetic properties (EM properties) are also attempted for the evaluation of the performance of concrete which is nonmetallic. For the economic manufacturing of concrete material, sea-sand is often used as aggregate, however, chloride ion in concrete has direct effects on steel corrosion and EM properties. In this study, OPC mortar specimens with 5 different chloride amount (0.0, 0.6, 1.2, 2.4, and $3.6kg/m^3$) and 3 different water-cement ratios (45%, 55%, and 65%) are prepared in order to investigate the EM properties corresponding to concrete properties. The EM properties of conductivity and dielectric constant are measured in the frequency range over 0.2~20 GHz. To facilitate the comparison of EM properties with chloride content, average values are taken respectively for the conductivity and dielectric constant measured over the 5~20 GHz frequency range. According to the results of this experiment, dielectric constant and conductivity are increased with lower W/C ratio and larger amount of chloride content.

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• v.12 no.2
• /
• pp.140-149
• /
• 2009

Purpose: Helicobacter pylori infection is probably acquired in childhood and persists as an asymptomatic infection for decades in most individuals. It is unclear why only a minority of those infected develop a clinical manifestation, even in childhood, such as peptic ulcer disease. H. pylori infection activates local immune responses and causes lymphocyte infiltration in the gastric mucosa. We have previously reported that both T and B cells in the lamina propria play important roles in the local immune response of H. pylori-infected children. The aim of this study was to investigate the association between H. pylori genotypes and gastric mucosal lymphocytes. Methods: Twenty-five H. pylori-infected children (10 with peptic ulcer disease and 15 with gastritis) were enrolled in this study. We investigated the genotypes (cagA, cagE, vacA, and babA2) and evaluated the association with clinical manifestations, histopathology, and gastric mucosal lymphocytes. Results: The prevalence of cagA, cagE, vacA s1m1, and babA2 was 80%, 60%, 84%, and 88%, respectively. The most prevalent (68%) combination of cagA, vacA, and babA2 genotypes was cagA+/vacA s1m1+/babA2+. H. pylori genotypes were not associated with clinical manifestations, histopathology, or gastric mucosal lymphocytes. Conclusion: There was no association between the cagA, cagE, vacA, or babA2 status and gastric mucosal lymphocytes. The role of the host immune response in relation to H. pylori genotypes and disease potential in children needs further studies.

• Horticultural Science & Technology
• /
• v.17 no.4
• /
• pp.473-475
• /
• 1999

This study was carried out to restore the fertility by suppression of male sterility-induced gene using an antisense construct. Tobacco (cv. Petit Havana SR1) was transformed with the binary vector containing a GBAN215-6 promoter, an antisense diphtheria toxin (DTx-A) gene (pKDA215b) and a hygromycin resistant gene. Seventy-six confirmed transgenic plants regenerated from leaf disks were designated as the $R_0$ generation and selfed to produce the $R_1$ generation. From the inheritance study, five $R_1$ lines with multiple copies of the antisense construct were selected and selfed to identify homozygosity for the antisense construct. In order to restore fertility and finally to select restore lines, five $R_2$ lines with multiple copies of the antisense construct were crossed with male sterile plants. From these crosses, three different phenotypes have been observed: completely restored, partially restored, and not restored pollens, and otherwise tobacco plants were phenotypically same as normal plants. These plants were scored for the degree of restoration and selected for further study.

• Clinical and Experimental Pediatrics
• /
• v.49 no.9
• /
• pp.983-986
• /
• 2006

Purpose : The purpose of this study was to investigate the presence of Bartonella henselae DNA, which is known as an etiologic agent of lymphadenitis, in fleas from dogs. Methods : The Bartonella henselae infection was investigated in 42 fleas from 22 dogs in Korea. By using seminested PCR targeting pap31 gene, B. henselae DNA was amplified from fleas. Results : B. henselae DNA was detected in seven fleas (7 of 42 fleas, 16.7 percent) from four dogs (4 of 22 dogs, 18.2 percent). To confirm these findings, we performed sequencing and identified the seven PCR products. Sequence analysis revealed that six sequences belonged to Huston-1 genogroup and one sequence to Marseille genogroup. Conclusion : These results may suggest that dogs could be an important source of B. henselae infection in children in Korea. This is the first report about the detection of B. henselae in fleas from dogs in Korea.

• Journal of Life Science
• /
• v.27 no.1
• /
• pp.89-94
• /
• 2017

DNA sequences of the intergenic spacer 1 and intergenic spacer 2 of the nineteen plants belonging Vitis genus were collected from the Genbank. DNA sequences of the same regions of Vitis thunbergii var. sinuata and Ampelopsis brevipedunculata var. heterophylla, both common plants in Korea, were not available in Genbank. Those two plants were collected, their genomic DNA encoding 18S rRNA, intergenic spacer 1, 5.8S rRNA, intergenic spacer 2 and part of 28S rRNA amplified and DNA sequence determined. DNA sequences of twenty-one plants including two Korean plants were aligned by the Multiple sequence comparison by log-expectation(MUSCLE) algorithm and the alignment was used to calculate neighbor-joining tree and pairwise distance. The results indicate DNA sequences of the two Korean plants are highly homologous with each other, but they are quite distantly related to the other Vitis plants. Distant relationship of the two Korean plants with the other Vitis plants might be due to independent evolution of those two plants in geographically isolated environment. Those two Korean plants are classified in different genera based on the morphology, one in Vitis genus and the other in Ampelopsis genus, providing another example of discrepancy between morphological and genetic classification.

• Journal of Genetic Medicine
• /
• v.6 no.2
• /
• pp.146-154
• /
• 2009

Multiplex ligation dependent probe amplification (MLPA) is a PCR-based method to detect gene dosage. Since its introduction, MLPA has been used to test a large number of genes for major deletions or duplications. Genetic testing, as a diagnostic tool for genetic disease, has been used primarily to identify point mutations, including base substitutions and small insertions/deletions, using PCR and sequence analysis. However, it is difficult to identify large deletions or duplications using routine PCR- gel based assays, especially in heterozygotes. The MLPA is a more feasible method for identification of gene dosage than another routine PCR-based methods, and better able to detect deleterious deletions or duplications. In addition to detection of gene dosage, MLPA can be applied to identify methylation patterns of target genes, aneuploidy during prenatal diagnoses, and large deletions or duplications that may be associated with various cancers. The MLPA method offers numerous advantages, as it requires only a small amount of template DNA, is applicable to a wide variety of applications, and is high-throughput. On the other hand, this method suffers from disadvantages including the possibility of false positive results affected by template DNA quality, difficulties identifying SNPs located in probe sequences, and analytical complications in quantitative aspects.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.9
• /
• pp.744-750
• /
• 2013

In this paper, we proposed new type of an artificial magnetic conductor(AMC) structure, which has a high impedance surface for realizing the meta-material characteristics. The designed AMC structure set a goal of 3.2GHz, and the reflector, which consists of periodically arrayed AMCs is fabricated and measured. The high impedance improves the reflection coefficient, decreases the system size and interference, and increases the antenna performance. The structure has embodied the high impedance by the thickness and relative permitivity of the dielectric substrate and the design configuration without the metallic via hole which connects the AMC to the GND. The bandwidth is 150% broader than the similar AMC structures. Also, the distance between the antenna and the AMC reflector is decreased by ${\lambda}/10$ as working as the metal(PEC) reflectors. The antenna radiation characteristics are 3dB increased at 10mm away from reflector by measurement. The proposed reflector could be inserted in the portable mobile devices, and the antenna's performance has improved by the reflector. The specific absorption rate is dramatically decreased over 94% because the back radiation of the antenna is shielded.

• Korean Journal of Microbiology
• /
• v.55 no.2
• /
• pp.103-111
• /
• 2019

DNA methylation is involved in diverse processes in bacteria, including maintenance of genome integrity and regulation of gene expression. CcrM, the DNA methyltransferase conserved in Alphaproteobacterial species, carries out $N^6$-adenine or $N^4$-cytosine methyltransferase activities using S-adenosyl methionine as a co-substrate. Celeribacter marinus IMCC12053 from the Alphaproteobacterial group was isolated from a marine environment. Single molecule real-time sequencing method (SMRT) was used to detect the methylation patterns of C. marinus IMCC12053. Gibbs motif sampler program was used to observe the conversion of adenosine of 5'-GANTC-3' to $N^6$-methyladenosine and conversion of $N^4$-cytosine of 5'-GpC-3' to $N^4$-methylcytosine. Exocyclic DNA methyltransferase from the genome of strain IMCC12053 was chosen using phylogenetic analysis and $N^4$-cytosine methyltransferase was cloned. IPTG inducer was used to confirm the methylation activity of DNA methylase, and cloned into a pQE30 vector using dam-/dcm- E. coli as the expression host. The genomic DNA and the plasmid carrying methylase-encoding sequences were extracted and cleaved with restriction enzymes that were sensitive to methylation, to confirm the methylation activity. These methylases protected the restriction enzyme site once IPTG-induced methylases methylated the chromosome and plasmid, harboring the DNA methylase. In this study, cloned exocyclic DNA methylases were investigated for potential use as a novel type of GpC methylase for molecular biology and epigenetics.

• Korean Journal of Plant Resources
• /
• v.36 no.4
• /
• pp.290-298
• /
• 2023

Several members of the genus Broussonetia are woody plants with high-quality cellulose fibers and are used to make a traditional type of Korean paper known as Hanji. Three of these species, Broussonetia kazinoki, Broussonetia monoica, and Broussonetia papyrifera, are found in the Korean Peninsula. Because it is challenging to distinguish different Broussonetia species based on morphology alone, we have developed a set of insertion/deletion (InDel) markers for genetic identification of these species. From twenty-two Broussonetia samples collected throughout Korea, we selected six for next-generation sequencing analysis. InDel marker candidates were identified by comparing this sequence information with the B. kazinoki chloroplast genome sequence. The marker candidates were used to screen the genomes of the twenty-two Broussonetia plants, and five useful chloroplast-based InDel markers were identified. Detailed genotyping using these five markers showed that the twenty-two plants of the genus Broussonetia could be clustered into five groups, verifying that the markers developed here can be used for breeding, identification, and analysis of species in the genus Broussonetia.