• The Plant Pathology Journal
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• v.18 no.6
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• pp.342-344
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• 2002

Apple scar skin viroid (ASSVd) has been one of the most destructive diseases in Korean apple orchards. Symptoms of the scar skin viroid disease were detected in various apple cultivars, namely, Sansa, Fuji, Chukwang, Miki-Life, Hongro, and Songbongeum cultivated in the southern part of Korea. The RNA molecules were extracted from the apples bearing dapple apple symptoms with the application of CF-11 RNA extraction method. The purified RNAs were used for the synthesis of cDNA with RT-PCR. The PCR products were cloned and sequenced. The viroid RNA molecules from the six different cultivars bearing the dapple symptos showed the same nucleotide sequences as that of the Korean strain of ASSVd（ASSVd-K). ASSVd-K was detected from apple orchards in Kunwi, Sangju, Uiseong, Yeong-yang, Andong, and Youngduk in Gyeongbuk Province in 2001, and in Muju in Jeonbuk Province in 2002. As the viroid disease could be propagated vegetatively, it can be widely transmitted gradually in Korea.

• International Journal of Industrial Entomology and Biomaterials
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• v.15 no.2
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• pp.93-100
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• 2007

After a serial study on the therapeutic efficacy of the powdery silkworm for diabetics was positively resulted in, many powdery silkworm products were on the market in Korea. Up to now, however, no causal method is available to discriminate the strain of silkworms that is a major ingredient for manufacturing powdery silkworm, even though the quality of the powdery silkworm differs greatly by source and origin of strains. We previously were successful in identifying 25 silkworm strains kept in Korea using nine intronic sequences. In this study, we tested the utility of the nine intronic sequences to distinguish the most widely reared silkworm strains originated from Korea and China. Two intron regions, PTTH Intron3 and PTTH Intron3, showed a substantial sequence divergence (mean sequence divergence of 3.13% in PTTH Intron3 and 4.99% in PTTH Intron3). These two intronic sequences provided no identical sequences among the seven strains tested. Thus, these sequences each along can be used to discriminate the seven strains tested in this study. Furthermore, other intron regions, except for VDP Intron4 allowed us to discriminate $2{\sim}4$ strains by strain-specific unique insertion/deletion or substitution.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.235-239
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• 1994

In this paper, the fatigue behaviour of typical axisymmetric forward extrusion die is investigated and extrusion process is analyzed by the rigid-plastic finite element method and elasto-plastic finite element method. To approach the crack problem involving crack initiation and propagation in extrusion die, LEFM(Linear Elastic Fracture Mechanics) is introduced and singular element which models stress.strain singularity in the crack tip vincity has been used to obtain an accurate stress intensityu factor values and other results. Form the displacement around the crack tip the stress intensity factor and the effective stress intensity factor at the beginning of the die inlet radius has been calculated. Applying proper fatigue crack propagation criterion such as Paris/Erdogan fatigue law to this data the angle and direction of fatigue crack growth has been simulated and these are compared with some experimental results. Using the computed crack growth rate, fatigue life of the extrusion die has been evaluated.

• Microbiology and Biotechnology Letters
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• v.38 no.1
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• pp.24-31
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• 2010

For the research of the natural marine antioxidant, an antioxidant-producing marine actinomycetes was isolated from sea water in Jeju coastal area. The strain was identified based on 16S rDNA sequencing, the morphology by a method of scanning electron microscopy, physiological and biochemical characteristics and cellular fatty acid analysis. The isolated strain ACT-18 was gram positive, aerobic, non-motile spores. Substrate mycelia are dark green and yellow gray aerial mycelia. The cell size of the strain was $0.5{\sim}1.0\;{\mu}m$. 16S rDNA sequence analysis showed that were Gram-positive bacteria grouped on Streptomyces sp. Results of cellular fatty acid analysis showed that major cellular fatty acids were $C_{15:0}$ anteiso (39.33%), $C_{16:1}$ cis 9 (11.96%), $C_{16:0}$ (13.08%) and $C_{17:0}$ anteiso (10.99%). The antioxidant activity of methanol extract from Streptomyce sp. ACT-18 was evaluated by measuring 1,1-diphenyl- 2-picrylhydrazyl (DPPH), hydroxyl, and alkyl radical scavenging activity using an electron spin resonance (ESR) spectrometer. DPPH radical scavenging activity of SBME (Streptomyces Broth Methanol Extract) A-18 was 46% at 0.1 mg/mL. Hydroxyl radical scavenging activity of SBME A-18 was 63% at 0.1 mg/mL. Alkyl radical scavenging activity of SBME A-18 was 39% at 0.1 mg/mL.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.6 s.237
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• pp.815-821
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• 2005

Biaxial low cycle fatigue test was carried out to predict fatigue life under combined axial-torsional-loading condition which is that of in-phase and out-of-phase for CF8M cast stainless steels. Fatemi-Socie(FS) parameter which is based on critical plane approach is not only one of methods but also the best method that can predict fatigue life under biaxial loading condition. But the result showed that, biaxial fatigue life prediction by using FS parameter with several different parameters for the CF8M cast stainless steels is not conservative but best results. So in this present research, we proposed new fatigue life prediction parameter considering effective shear stress instead of FS parameter which considers the maximum normal stress acting on maximum shear strain and its effectiveness was verified.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.114-119
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• 2004

Endbeam is an important structural member of freight bogie for the support of service loading. In general, more than 25 years' durability is necessary. However, endbeam occur fatigue fracture in dynamic stress concentration location because comparatively strength and stiffness are low. Therefore, structure analysis is performed to evaluate structural problem of endbeam and local strain range as durability analysis. The number of cycles is extracted concerning the bogie in operation by measurement dynamic stress time history on critical part which is crack initiation in actual fact. At this time rainflow cycle counting is used to consider change of stress for operating condition. Based on the fatigue life curves and the stress analysis, the fatigue life of the endbeam is predicted and compared with the experimentally determined fatigue life, resulting in a fairly good correlation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.724-730
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• 2010

A load cell is a converter that generates voltage signals when a certain force is effected in a given direction. An essential measurement device for electronic scales that indicate weight by numbers. These load cells are being applied in various areas such as daily life, distribution, laboratory and industrial. Recently the study to manufacture load cells in a more simple method while increasing performance is being persisted. In this study based on the comparison of load cells manufactured through single surface processing using strain gauges. Those manufactured through dual surface processing using strain gauges. Ultimately persist a more simple method of load cell manufacturing while increasing its performance. The elements that were compared were linearity, hysteresis, creep and eccentricity which are short tenn performance factors. The conclusion was that single surface processing showed almost identical data as that of dual surface processing, and the load cell error rate(0.005%) also excess regulation. The manufacturing time was shortened while mass-production was possible. Which indicates a development in the weighing industry.

• Journal of Ocean Engineering and Technology
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• v.13 no.1 s.31
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• pp.1-10
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• 1999

The engine exhaustive valve became essential as the important element. The dissimmilar welding method of exhaustive valve head to stem was asked for manufacturing the engine exhaustive valve, for which the electric resistance are welding has been conventionally used, resulting in poor quality of the welded joint. In this paper, not only the development of optimizing of friction welding with more reliability and more applicability but also the development of in-process real-time weld qudlity(such as strength and toughness) evaluation technique by acoustic emission for friction welding of the engine exhaustive valve(SUH3-SUH35 dissimilar steels) were perfomed. The high temperature(500, 500, 600$^{circ}$C) creep properties prediction of the friction welded joint of SUH3-SUH35 was investigated relating to the initial strain meethod(ISM) as a new approach, resulting in obtaining an experimental equation of creep life prediction.

• Composites Research
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• v.31 no.6
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• pp.332-339
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• 2018

Fiber metal hybrid laminate (FML) can be used as an economic material with superior mechanical properties and light weight than conventional metal by bonding of metal and FRP. However, there are disadvantages that it is difficult to predict fracture behavior because of the large difference in properties depending on the type of fiber and lamination conditions. In this paper, we study the failure behavior of hybrid materials with laminated glass fiber reinforced plastics (GFRP, GEP118, woven type) in Al6061-T6 alloy. The Al alloys were coated with GFRP 1, 3, and 5 layers, and fracture behavior was analyzed by using a static test and a low cycle fatigue test. In the low cycle fatigue test, strain - life analysis and the total strain energy density method were used to analyze and predict the fatigue life. The Al alloy did not have tensile properties strengthening effect due to the GFRP coating. The fatigue hysteresis geometry followed the behavior of the Al alloy, the base material, regardless of the GFRP coating and number of coatings. As a result of the low cycle fatigue test, the fatigue strength was increased by the coating of GFRP, but it did not increase proportionally with the number of GFRP layers.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.911-917
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• 2010

In this study, we performed structural and fatigue analyses of the engine exhaust manifold that was subjected to thermo-mechanical cyclic loading. The methodologies used in this study are based on an approach in which the techniques for modeling the exhaust system, the temperature-dependent properties of the material, and thermal cyclic loading are taken into consideration and a reliable strategy is adopted for failure prediction. An application example shows that at an elevated temperature, considerable compressive plastic deformation is observed and that at a low temperature, tensile stresses remain in those parts of the test exhaust manifold where failure is observed. In order to predict fatigue life, mechanical damage is determined on the basis of the stress.strain hysteresis loops by using the classical Coffin.Manson equation and by adopting a method in which the dissipated plastic energy is taken into consideration.