• Research in Plant Disease
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• v.29 no.3
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• pp.304-309
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• 2023

Wilted and water-soaked lesion symptoms were observed on cucumbers in greenhouses located in Daejeon, Chungcheongnam-do, Korea, in June 2021. A bacterial strain, designated KNUB-04-21, was isolated from the cucumbers, which was subsequently identified as Pectobacterium brasiliense through a phylogenetic analysis based on sequences of the 16S rRNA region, dnaX, leuS, and recA genes. The biochemical characteristics of KNUB-04-21 were also similar to those of P. brasiliense through investigation using the API ID 32 GN system. The pathogenicity of KNUB-04-21 was confirmed by inoculating it into healthy cucumber plants. The reisolated strains were also found to be same to the original strain. To our knowledge, this is the first report of P. brasiliense being identified as the causative agent of cucumber soft rot in Korea.

• International Journal of Korean Welding Society
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• v.1 no.2
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• pp.30-35
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• 2001

Nowadays, repair welding on in-service natural gas pipeline is a matter of primary concern of gas company. The main purpose of this study is to investigate the effects of welding conditions on the allowable heat input for crack-free welds and welds without burn-through onto in-service natural gas pipeline. First of all, single pass weld bead on plates of the various thickness was deposited to evaluate the penetration of weld metal, the depth of heat affected zone and the hardness of repair weld under various welding conditions. Also, finite element analysis has been conducted to validate experimental results of bead-on plate welds and to develop appropriate model for repair welding. The welding experiments of bead-on-plate weld confirmed the influence of plate thickness, heat input and welding process on safety. And, the finite element model was demonstrated by comparing experimental results. The agreement between the computed and measured values was shown to be generally good. Therefore, It is possible to predict the safety of repair welding under various welding conditions with experimental results and finite element analysis model.

• Research in Plant Disease
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• v.29 no.4
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• pp.452-458
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• 2023

In the Goesan region, located in Chungcheongbuk-do, Korea, a significant outbreak of soft rot infections was documented in August 2021, affecting fruits of Momordica charantia, commonly known as bitter melon or bitter gourd. The symptoms included a noticeable transition to yellowing in the affected fruits, eventually leading to their collapse. The bacterial strain KNUB-09-21 was isolated from the diseased fruits. Molecular analysis, using the sequences of the 16S rRNA region and three housekeeping genes (dnaX, recA, and leuS), along with the results of compound utilization in the API ID 32 GN system, provide strong evidence for the identification of the isolate KNUB-09-21 as Pectobacterium brasiliense. The pathogenicity of strain KNUB-09-21 on M. charantia was confirmed through a controlled inoculation test. Within two days, inoculated fruits displayed soft rot symptoms closely resembling those observed in naturally affected fruits. This is the first report of soft rot on M. charantia in Korea.

• Transactions of Materials Processing
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• v.33 no.3
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• pp.208-213
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• 2024

Ni-based superalloys have exceptional performance in high-temperature strength, corrosion resistance, etc, and it has been widely used in various applications that require corrosion resistance at high-temperature operations. However, the relatively expensive cost of the Ni-based superalloys is one of the major hurdles. The corrosion-resisted alloy(CRA) clad materials can be a cost-effective solution. In this study, finite element analysis of the hot rolling process for manufacturing of the Alloy 625/API X65 steel CRA clad plates is conducted. The stress-strain curves of the two materials are measured in compressive tests for various temperature and strain rate conditions, using the Gleeble tester. Then, strain hardening behavior is modeled following the modified Johnson-Cook model. Finite element analysis of the hot rolled cladding process is performed using this strain rate and temperature dependent hardening model. Finally, the thickness ratio of the CRA and base material is predicted and compared with experimental values.

• Research in Plant Disease
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• v.30 no.1
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• pp.88-94
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• 2024

In July 2021, symptoms of soft rot were observed on the stems of Ficus carica in Yeongam, Jeollanamdo, Korea. To accurately diagnose the cause, infected stem was collected and bacterial strain was isolated. Among these, the pathogenic strain KNUB-08-21 was identified as Pectobacterium aroidearum through 16S rRNA gene sequencing and phylogenetic analysis based on the concatenated sequences of the dnaX, leuS, and recA genes. The affiliation of the isolate with this bacterial species was also confirmed by its biochemical characteristics obtained using API ID 32 GN system. Artificial inoculation confirmed the strain's pathogenicity in figs, causing significant damage to both stems and fruits. To our knowledge, this is the first report of P. aroidearum causing soft rot disease in F. carica in Korea.

• Korean Journal of Veterinary Research
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• v.16 no.1
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• pp.11-25
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• 1976

Studies on pathogenicities and developmental stages of Nosema apis (Zander, 1909) were carried out through artificial infection to Nosema free honey bees with various levels of spores isolated from local honey bee colony. The results obtained were summarized as follows: 1. The clinical symptoms were observed as dysentery, enteritis of mid-gut (enlargement and decoloration), crawling posture and shortening of the longevity of worker bees in the rearing honey bee colony inoculated with the spores. 2. Number of spores harvested from laboratory rearing honey bees were progresively increased to 4 weeks after inoculation. The regression equations and coefficients of correlations to various spore levels were as follows in each treatment colony. Colony 1. ($$1,000{\times}10^4spores/ml$$) $$y_{c1}=471{\times}10^{4}x+454{\times}10^4(r=0.65^*$$) Colony 2. ($$500{\times}10^4spores/ml$$) $$y_{c2}=340{\times}10^{4}x+207.8{\times}10^4(r=0.99^{**}$$) Colony 3. ($$100{\times}10^4spores/ml$$) $$y_{c3}=150{\times}10^{4}x+84.2{\times}10^4(r=0.99^{**}$$) Colony 4. ($$10{\times}10^4spores/ml$$) $$y_{c4}=13.8{\times}10^{4}x+13{\times}10^4(r=0.98^{**}$$) 3. Average longevity of worker bees artificially infected with Nosema apis was shortened as 21.7~43.8% compare to the control. (p<.05, p<.01) 4. The spores which were isolated from honey bee colony infected with Nosema disease were ovoid or spherical form, and measured, as a rule, from $4.7{\mu}m$ to $6.1{\mu}m$ (mean $5.3{\mu}m$) in length and from $2.4{\mu}m$ to $3.2{\mu}m$ (mean $2.9{\mu}m$) in width. 5. In the mid-gut of honey bees, the spore was progresively germinated and became trophozoite stage. The trophozoites were grown to meronts and their binary fission were begun. The divided two sporoblasts were developed to the spores which had elastic membrane. The new spores were shed in excreta of honey bees 10~15 day after inoculation at $25{\pm}2$ centigrade. 6. The ultrastructure of spore membrane consisted of three layers, such as, outer, middle and inner layer. The sporoplasm consisting lamellar structure occupied only anterior part of the spore and was often extended to posterior direction where definite vacuoles and a polar filament was able to detect.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.61-70
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• 2008

In this research, load-transfer-function method was selected, because that is widely used in geotechnical engineering among the analysis methods to verify the behavior of load-lateral displacement. Lateral loading test of field scale was conducted, this measured data was analyzed. From the analysis, the model of load-lateral displacement was suggested. The test results were studied and compared to the commercial programs, 'LPILE', which contain the load transfer functions proposed before. By analysis of measure data of load-lateral displacement that expressed to several functions, $y=ae^{bx}$ model was the simplest and applicable to the field. In that case a value converged about 1.3, b value had a tendency to converge about 0.02. From the comparison analysis between measured data and load transfer function by 'LPILE', it is examined that if the lateral load is small, calculated displacements of them show a similar value compared to measured values. Furthermore, the bigger lateral loads, the bigger calculated values compared to the measured data. If the results are compared by Matlock-Reese method and Matlock-API method, Matlock-Reese method shows result of safe side because lateral displacement is calculated greatly relatively.

• Journal of Ocean Engineering and Technology
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• v.17 no.2
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• pp.34-39
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• 2003

Recent deepwater offshore structures in the Gulf of Mexico utilize butt welded tubular joints. Application of a welded tubular joint includes tendons, production risers, and steel catenary risers. Fatigue life assessment of these joints becomes more critical, as the structures to which they are attached are allowed to undergo cyclic and sometimes large displacements around an anchored position. Estimation of the fatigue behavior of these tubular members in the design stage is generally condrcted by using S-N curves, as specified in the codeds and standards. Applying the stress concentration factor of the welded structure to the S-N approach often results in a very conservative assessment, because the stress field acting on the tubular has a non-uniform distribution through the thickness. Fatigue life analysis using fracture mechanics has been applied in the design of the catenary risers. This technology enables the engineer to establish proper requirements on weld quality and inspection acceptance criteria to assure satisfactory structural integrity during its design life. It also provides guidance on proper design curves and a methodology for accounting for the effects of non-uniform stress distribution through the wall thickness. Still, there is inconsistency when designing tubular joints using a conventional S-N approach and when specifying weld flaw acceptance criteria using fracture mechanics approach. This study developed fatigue curves that are consistent with both the S-N approach and the fracture mechanics approach. Accounting for non-uniform stress distribution and threshold stress intensity factor were key parameters in relating both approaches. A series of S-N curves, generated from the fracture mechanics approach, were compared to the existing S-N curves. For flat plate butt joint, the S-N curve generated from fracture mechanics matches with the IIW class 100 curve when initial crack depth was 0.5 mm (0.02 ). The new curves for tubular joint agree very well with the experimental results. The comparison also indicated the degree of conservatism built into the API X design curve.

• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.1-6
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• 2011

It is required to construct the pipelines to eliminate pressure drop at the end of transmission line under limitation of maximum operation pressure of 6.86 MPa, however, it highly costs to build the pipelines and takes time-consuming job. Higher operation pressure compared to current operating pressure has been considered to resolve the problem of pressure drop without modification of the existing pipelines and facilities. As a result of the integrity evaluation, the existing pipelines can be operated up to 7.85 MPa in terms of wall thickness and have higher Charpy impact energy than required value in the ASME B31.8. However, Increment of operation pressure gives rise to increase potential impact area if the pipelines burst due to third party damages.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.6 no.1
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• pp.69-74
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• 2003

Recent deepwater offshore structures in the Gulf of Mexico utilize butt welded tubular joints. Application of a welded tubular joint includes tendons, production risers, and steel catenary risers. Fatigue life assessment of these joints becomes more critical, as the structures to which they are attached are allowed to undergo cyclic and sometimes large displacements around an anchored position. Estimation of the fatigue behavior of these tubular members in the design stage is generally conducted by using S-N curves, as specified in the codes and standards. Applying the stress concentration factor of the welded structure to the S-N approach often results in a very conservative assessment, because the stress field acting on the tubular has a non-uniform distribution through the thickness. Fatigue life analysis using fracture mechanics has been applied in the design of the catenary risers. This technology enables the engineer to establish proper requirements on weld quality and inspection acceptance criteria to assure satisfactory structural integrity during its design life. It also provides guidance on proper design curves and a methodology for accounting for the effects of non-uniform stress distribution through the wall thickness. Still, there is inconsistency when designing tubular joints using a conventional S-N approach and when specifying weld flaw acceptance criteria using fracture mechanics approach. This study developed fatigue curves that are consistent with both the S-N approach and the fracture mechanics approach. Accounting for non-uniform stress distribution and threshold stress intensity factor were key parameters in relating both approaches. A series of S-N curves, generated from the fracture mechanics approach, were compared to the existing S-N curves. For flat plate butt joint, the S-N curve generated from fracture mechanics matches with the IIW class 100 curve when initial crack depth was 0.5 mm (0.02). The new curves for tubular joint agree very well with the experimental results. The comparison also indicated the degree of conservatism built into the API X design curve.