• 대한공업교육학회지
• /
• v.32 no.1
• /
• pp.134-152
• /
• 2007

This study deals with the development of computer program which can restrict students to access to the unallowable web sites during the Internet based class. Our suggested program can find the student's access list to the unallowable sites, display it on the teacher's computer screen. Through the limitation of the student's access, teacher can enhance the efficiency of class and fulfill his educational purpose for the class. The use of our results leads to the effective and safe utilization of the Internet as the teaching tools in the class. Meanwhile, the typical method is to turn off the LAN (Local Area Network) power in order to limit the student's access to the unallowable web sites. Our program has been developed on the Linux operating systems in the small network environment. The program includes following five functions: the translation function to change the domain name into the IP(Internet Protocol) address, the search function to find the active students' computers, the packet snoop to capture the ongoing packets and investigate their contents, the comparison function to compare the captured packet contents with the predefined access restriction IP address list, and the restriction function to limit the network access when the destination IP address is equal to the IP address in the access restriction list. Our program can capture all passing packets through the computer laboratory in real time and exactly. In addition, it provides teacher's computer screen with the all relation information of students' access to the unallowable sites. Thus, teacher can limit the student's unallowable access immediately. The proposed program can be applied to the small network of the elementary, junior and senior high school. Our research results make a contribution toward the effective class management and the efficient computer laboratory management. The related researches provides teacher with the packet observation and the access limitation for only one host, but our suggested program provides teacher with those for all active hosts.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.351-351
• /
• 2006

The possible interactions between cyclodextrins and biodegradable polyesters were investigated. The hydrophobicity of cyclodextrin could be varied with the methyl substitution of host CD, and the possibility of IC formation and the types of interaction between respective CDs and polyesters were subsequently changed. Further, the effect of cyclodextrins on the morphological change of biodegradable polymer was shown to depend on the degree of IC formation between cyclodextrin and biodegradable polymer as well as on the type of interaction between respective CDs and polyesters. That is, the enhancement and/or the restriction of the crystallization of P(3HB) were observed by the incorporation of various kind of cyclodextrins with different cavity size and hydrophobicity.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 1995.06b
• /
• pp.21-25
• /
• 1995

;Bacterial blight caused by Xanthomonas oryzae pv. Olyzae is one of the most important diseases of rice. Host resistance, which relies on single, dominant resistance genes, is the only reliable method to control the disease at present. Pathogenic variation of the bacteria has been shown to follow the deployment of resistance genes in commercial cultivars. Information on the factors and the mechanisms for genetic variation of this pathogen is limited. Further, we have no clear evidence of whether population variability is due to sexual recombination or to variation introduced by mutations or intragenic recombination in a clonally maintained population.(omitted)itted)

• Korean Journal of Microbiology
• /
• v.25 no.1
• /
• pp.52-56
• /
• 1987

The evidences that Lam B protein of E. coli is used as a receptor for infections of bacteriophage N4 as well as bacteriophage lambda were obtained from the following experimental results. First, all of the isolated lambda resistant dlones possessing foreign DNA fragments in the plasmids were also resistant to bacteriophage N4, but not to bacteriophage $\phi$ 80, T4 and T7. Second, when the plasmid DNA was treated with various restriction enzymes and ligated to delete the total or a portion of the foreign DNA fragments, the deleted plasmids lost the resistant activities to lambda and N4, simultaneously. Third, after amplification of Lam B protein about 200 times by inducing the protein using maltose as a sole carbon source, the host E. coli became sensitive to both lambda and N4.

• The Korean Journal of Food And Nutrition
• /
• v.6 no.4
• /
• pp.314-321
• /
• 1993

We have cloned the Bacillus cellulyticus K-12 avicelase (Avi, E.C.3.2.1.4) gene (ace A) In E. coli. This was accompanied by using the vector PT7T3U 19 and Hind W -Hind m libraries of Bacillus cellulyticus K-12 chromosomal inserts created in 5.cofi. The Libraries were screened for the expression of avicelase by monitoring the immunoreaction of the anti-avicelase (immunoscreening). Positive clones (Ac-3, Ac-5, and Ac-7) contained the identical 3.5kb Hind III fragment as determined by restriction mapping and Southern hybridization, and expressed avicelase efficiently and constituvely using its own promoter in the heterologous host. From the immunoblotting analysis, a polypeptide which showed a CMCase activity with an Mr of 54000 was detected.

• Korean journal of applied entomology
• /
• v.36 no.1
• /
• pp.96-104
• /
• 1997

A silkworm Bombyx mori genomic DNA library was constructed from polyphagous J111 strain and unpolyphagous $C_3$ strain to develop the genomic study by DNA makers. Genomic DNAs of two strains were digested with restriction enzyme EcoRI and ligated into pUC18. The ligated plasmids were transferred into E. coli host strain DH5$\alpha$. When the genomic DNAs were hybridized with insert DNAs from transformant, could be categorized from hybridization patterns to three groups as high repetitive sequence, moderately repetitive sequence, and low-copy number sequences. A total of 219 clones containing single or low-copy number sequence inserts were examined for any polymorphisms between two strains of J111 and $C_3$. Forty six clones showed RFLPs and 10 of these clones were used as a probe of analysis of $F_2$ population derived from crossing between J111 and $C_3$ strain. The genetic inheritance tested with each clones will be important tools to construct the genetic map of the silkworm, Bombyx mori.

• Microbiology and Biotechnology Letters
• /
• v.14 no.2
• /
• pp.161-168
• /
• 1986

A 1.95Kb Sau3Al fragment coding for $\alpha$-amylase from Bacillus amyloliquefaciens was isolated by the shotgun method using Escherichia coli as a host. The genome of Bacillus amyloliquefaciens was partially digested with the restriction endonuclease Sau3Al and joined to plasmid YRp7 cleaved with the restriction endonuclease BamHI. The $\alpha$-amylase gene present in a 1.95Kb insert was stably maintained and expressed in Escherichia coli. The amount of $\alpha$-amylase activity produced by Escherichia coli containing the hybrid plasmid pEA24 was about 65% of the activity produced by the donor Bacillus amyloliquefaciens strain. The properties of $\alpha$-amylase produced by Escherichia coli were very similar to those produced by Bacillus amyloliquefaciens as based on optimum temperature, pH, and effect of CaCl$_2$ concentration. About 70% of the $\alpha$-amylase produced by Escherichia coli was localized in the periplasmic space, whereas the remaining enzyme was localized in the inner part of the cell.

• Research in Plant Disease
• /
• v.29 no.4
• /
• pp.420-424
• /
• 2023

In 2020, within the Dongbaekdongsan area in Jeju Island, a Septobasidium sp. associated with a felt disease in Castanopsis sieboldii (Makino) Hatus. ex T. Yamaz. & Mashiba was identified. The symptom included the presence of brown, thin, and silk-like mycelial mats attached to the tree's bark, displaying variations in size from large to small. To induce hyphal growth, the samples collected were incubated in a moist chamber, and the newly formed hyphae were subjected to genomic DNA extractions. The nucleotide sequences of the internal transcribed spacer and small subunit rDNA genes were determined, and molecular characteristics among the isolates were investigated through polymerase chain reaction-based restriction fragment length polymorphism analysis. This Septobasidium sp. exhibited distinct morphological and phylogenetic features compared to those that were previously reported in South Korea. Consequently, this strain is taxonomically classified as a provisionally novel species of Septobasidium. Furthermore, the observed felt disease exhibited a high degree of host specificity, as it was exclusively identified in C. sieboldii without occurrence in other tree species at the time of observation.

• Journal of Sericultural and Entomological Science
• /
• v.38 no.1
• /
• pp.36-41
• /
• 1996

Recombinant baculoviruses having expanded host range were selected by coinfection of Autographa california NPV and Bombyx mori NPV into Sf-9 and BmN-4 insect cell lines. In order to determine the polyhedra morhplogy of RecS-A6, one of a recombinant baculovirus, polyhedra of RecS-A6 produced in insect cells were observed by phase contrast microscope and scanning electron microscope. The results revealed that the recombinant baculovirus had a various polyhedra morphology which was different from its parental viruses, suggesting that the various morhpology of recombinant baculovirus with an expanded host range was due to the genetic recombination of viral genome. To analyze the genomic recombinantion of the recombinant baculoviruses, genomic DNAs of two parent viruses and RecS-A6 were digested with restriction endonuclease and subjected to agarose gel electrophoresis. Southern blot analysis revealed that RecS-A6 has two polyhedrin gene of AcNPV and BmNPV in a viral genome. Polyhedral protein of recombinant baculovirus was analysed by SDS-PAGE. The result showed that molecular weight of polyhedral protein of RecS-A6 containing two polyhedrin gene of AcNPV and BmNPV was as the 31 kDa band of AcNPV and 30 kDa band of BmNPV.

• The Journal of the Korean Society for Microbiology
• /
• v.34 no.6
• /
• pp.519-532
• /
• 1999

Helicobacter pylori is a causative agent of type B gastritis and plays a central role in the pathogenesis of gastroduodenal ulcer and gastric cancer. To elucidate the host-parasite relationship of the H. pylori infection on the basis of molecular biology, we tried to evaluate the genomic diversity of H. pylori. An ordered overlapping bacterial artificial chromosome (BAC) library of a Korean isolate, H. pylori 51 was constructed to set up a genomic map. A circular physical map was constructed by aligning ApaI, NotI and SfiI-digested chromosomal DNA. When the physical map of H. pylori 51 was compared to that of unrelated strain, H. pylori 26695, completely different restriction patterns were shown. Fifteen known genes were mapped on the chromosome of H. pylori 51 and the genetic map was compared with those of strain 26695 and J99, of which the entire genomic sequences were reported. There were some variability in the gene location as well as gene order among three strains. For further analysis on the genomic diversity of H. pylori, when comparing the genomic structure of 150 H. pylori Korean isolates with one another, genomic macrodiversity of H. pylori was characterized by several features: whether or not susceptible to restriction digestion of the chromsome, variation in chromosomal restriction fingerprint and/or high frequency of gene rearrangement. We also examined the extent of allelic variation in nucleotide or deduced amino acid sequences at the individual gene level. fucT, cagA and vacA were confirmed to carry regions of high variation in nucleotide sequence among strains. The plasticity zone and strain-specific genes of H. pylori 51 were analyzed and compared with the former two genomic sequences. It should be noted that the H. pylori 51-specific sequences were dispersed on the chromosome, not congregated in the plasticity zone unlike J99- or 26695-specific genes, suggesting the high frequency of gene rearrangement in H. pylori genome. The genome of H. pylori 51 shows differences in the overall genomic organization, gene order, and even in the nucleotide sequences among the H. pylori strains, which are far greater than the differences reported on the genomic diversity of H. pylori.