• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.4
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• pp.278-285
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• 1991

The authors propose to use the slot system in order to improve of the efficiency for the cambered otter boards. The experiment is divided into 2 parts, one is the efficiency model test, and the other is the visualization model test. The hydrodynamic characteristics of the model otter boards were tested by efficiency model test to measure the shearing, drag force of the models and visualization test using hydrogen bubble method to observe the streak-line and time-line of flow around the models, and milk spout method to observe the separation zone in the wake behind the models. This study tested for 5 models such ad without slot, slot position 0.2C, 0.4C, 0.6C and 0.8C. The results obtained are as follows: \circled1 The maximum C sub(L) of model otter board with slot position 0.6C in attack angle 27$^{\circ}$ was the highest of all models, it's value was 1.59. \circled2 In general, the L/D ratio of the one slot otter boards were 16~28% higher than otter board without slot. \circled3 The slot position 0.6C was better than any other slot position, and it's conformed by visiualization. \circled4 As to the model otter board with slot position 0.6C, flow speed of the back side was faster 1.3 to 1.7 times than in the front side. \circled5 The size of the separated zone in case of the model otter board with 0.6C was smaller than that of any other models.

• The Plant Pathology Journal
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• v.18 no.4
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• pp.192-198
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• 2002

Mixed infections of two economically important viruses, Turnip mosaic virus(TuMV) in the family Potyviridae and Ribgrass mosaic virus(RMV) in the genus Tobamo-virus, were studied ultrastructurally on oriental cabbage. TuMV-ACl8 (alpine isolate in Korea) induced chlorotic spots on inoculated leaves of both ‘SSD63’ inbred line known as susceptible to TuMV, and ‘Tambok’ commercial cultivar, known as resistant to the virus, in the early stages of infection. TuMV-C5 (Taiwan isolate) caused severe mosaic and malformation on the upper leaves of ‘SSD63’, and necrotic spots in both inoculated and upper leaves of ‘Tambok’. RMV-CA1 (oriental cabbage isolate from alpine in Korea) induced vein chlorosis, leaf malformation, and midrib necrotic streak in the upper leaves of both ‘SSD63’ and ‘Tambok’. Both oriental cabbages infected with a combination of TuMV-ACl8 and RMV-CA1 showed synergistic symptoms of severe yellowing, severe mosaic, and necrotic spot or vein necrosis on their leaves. A combination of TuMV-C5 and RMV-CA1 produced synergistic symptoms only in ‘SSD63’. In ‘Tambok’ infected with the combination of TuMV-C5 and RMV-CA1, the number of necrotic spots on the inoculated leaves was one half lesser than that on singly infected with TuMV-C5. A few necrotic spots progressed systemically. In cells infected with a combination of TuMV-ACl8 and RMV-CA1 or TuMV-C5 and RMV-CA1, the particles of the two viruses made nonagon-like rings(NLR); one TuMV particle was surrounded loosely by nine RMV particles. Two unrelated viruses of TuMV and RMV were compacted in the central part of the spiral aggregates(SA) that was induced strikingly in cells by the mixed infections. The SA showed NLR in its center of the cross-sectioned side. Many particles of RMV of Tobamovirus were closely associated with Potyvirus-characteristic cylindrical inclusions. The SAs in the mixed infections were formed easily by the Potyvirus of TuMV-ACl8 or -C5 isolates.

• IMMUNE NETWORK
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• v.1 no.1
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• pp.61-69
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• 2001

Background: To determine the molecular structure of type II collagen-specific T-cell receptors associated with rheumatoid arthritis (RA). Methods: We generated CII-specific T-cell lines of 8 RA patients by prolonged in vitro culture with bovine CII (bCII) and the immunogenic peptide (256-270) of human CII. The proliferation response towards CII stimulation was measured from the uptake of 3H-thymidine. Changes in the secretion of Th 1 and Th2 cytokines in the culture supernatent were measured by ELISA. The TCR clonotypes of these T-cells were examined by RT-PCR/SSCP analyses of all 22 $V_{\beta}$ chains. Results: T-cells from patients' tissue exhibited strong proliferation index upon CII stimulation, which was maintained up to 6 months in the culture. The secretion of INF-$\gamma$from these T-cells increased along with the duration of culture time, while the amount of IL-4 production did not show significant changes. The SSCP band patterns of patients' T-cells appear as discrete bands unlike the smeary streak produced from normal samples. Some SSCP bands, each representing selected expansion of a TCR containing certain subtype of $V_{\beta}$ peptides, appeared to be identical in more than one patients. Among these, the expansion of SSCP band representing the $V_{\beta}$ 14 CDR3 region persisted after switching the antigen to the immunogenic human peptide (256-270). Conclusion: CII-reactive T-cells expressing distinct CDR3 motifs are selectively expanded in the peripheral blood and synovial fluid of RA patients, and their persistent proliferation upon CII stimulation, as well as the production Th 1-type cytokines, may play pivotal roles in RA pathogenesis.