• Mycobiology
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• v.42 no.4
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• pp.405-408
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• 2014

Leaf spot disease was observed in sesame (Sesamum indicum L.) during 2009 and 2010 in Korea. The pathogen was identified as Alternaria simsimi based on morphological and cultural characteristics. The morphological identification was well supported by phylogenetic analysis of the ribosomal DNA-internal transcribed spacer region. A. simsimi isolates caused spot symptoms on leaves and stems of sesame plants 2 wk after artificial inoculation, which were similar to those observed in the field. This is the first record of leaf spot disease in Korea caused by A. simsimi.

• Korean journal of applied entomology
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• v.39 no.4
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• pp.259-266
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• 2000

This study was carried out to investigate the status of spot damage by fruit piercing pests and the kinds of these pests on yuzu (Citrus junos) fruit in Koheung, the most chief producing district of yuzu fruit in Korea, from ’97 to ’99. The extent of spot damage by fruit piercing pests on yuzu was increasing in recent years. This damage of fruits was severe in the lower canopy than the high one from ground and intercropping groves between yuzu trees had a greater damage to compare with single cropping of yuzu. Spot damage of yuzu fruit was occurred mainly from late September to early November when yuzu fruit is enlarging and coloring yellow. The blackish concave spot on yuzu fruit surface was appeared in 3 days after introduction of Riptortus clavatus into a netted cage containing one yuzu fruit and the diameters of this spot was 8.3 mm. At 10 days after introduction, this spot changed into milky-white with 9.2 mm diameters. One concave spot has contained oil cells by 17.7 and its external appearances has unchanged until harvest. The kinds of piercing pests of yuzu fruit were investigated with 3 orders, 16 families and 37 species. These pests were classified by 11 species of bugs, 5 species of hoppers and 21 species of moths. Among them, dominant species were Physopelta gutta, Halyamorpha halys, Empoasca vitis, Aedia leucomelas, Agrotis tokionis, etc. Macroglossum bombylans and Acherontia s쇼x are newly confirmed species as the fruit piercing moths in Korea.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.314-318
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• 2004

This research is conducted to investigate weldability characteristics with various welding conditions on the 4 lap spot welded joint of structural steel sheets in automobile. The relationship between the tensile-shear strength and the indentation depth has been investigated to evaluate the weldability and the optimum welding conditions. The welding current and the welding time have a greatly affect to the tensile-shear strength compared to the electrode force. It was found that the indentation depth has a relatively close relationship with the expulsion occurrence. The optimum welding conditions were proposed for the 4 lap spot welded joint.

• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.43-49
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• 2002

In this Paper, the mechanical behavior of two reかangular plates spot-welded under free vibration is investigated in detail. The focus of the analysis is to evaluate the effect of thickness of reinforced plates with equivalent thickness. The results of this the investigation are compared with detailed finite element analysis end experiments of the plates spot-welded for various parameters, such as aspect ratio, arm ratio, and distance ratio of spot-welding Points. The conclusion obtained are as followed. 1. The effect thickness due to spot-weld is very large, such as 55% in comparison with area ratio of spot-welding joint is just 4.52%. 2 The effect of thickness with respect to the distance ratio is maximized when the distance ratio is 0.4.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.27-33
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• 1997

Spot welding has been used in the sheet metal jointing processes because of its high productivity and convenience. In this study, effects of welding conditions on the fatigue life and prediction methods of fatigue life of spot welded joint have been studded . Fatigue life was estimated by stress index parameter considering multiaxial stresses. Fatigue tests were conducted with the tensile-shear specimens using SPCC. Fatigue life of spot welded joint was influenced by welding currents and was predicted exactly with taking into account StageIII.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.4
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• pp.347-355
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• 2005

We investigate the distribution of central spot and the encircled energy in order to assess the performance of central obstructed optical system having central obstruction, when the central obstruction and the degree of truncated Gaussian amplitude of incident beam change. When the radius of central obstruction increases the radius of central spot on the image plane decreases, and when the degree of truncated Gaussian amplitude of incident beam increases the radius of central spot on the image plane increases. As the central obstruction and the degree of truncated Gaussian amplitude of incident beam increase, the depth of focus increases and the encircled energy of central spot decreases. We know from theses results that the effect of Gaussian factor is small as the central obstruction increases. These results was applied to develope the large optical reflection system.

• Journal of Mechanical Science and Technology
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• v.17 no.4
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• pp.501-510
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• 2003

The spot welded sections of automobiles such as the hat and double hat section members, absorb the most of the energy during the front-end collision. The purpose of this study was to analyze the collapse characteristics of spot welded section members with respect ttl the pitch or spot welds on flanges. through impact experiments and computation for para-closed sections and perfectly closed sections. The hat shaped section members were tested at the impact collapse velocities of 4.72 m/sec, 6.54 m/sec and 7.19 m/sec and double hat shaped section members were tested at the impact collapse velocities of 6.54 m/sec, 7.19 m/sec and 7.27 m/sec. A commercial LS-DYNA3D was used to simulate the collapse behavior of the hat and double hat shaped section members. The validity of the simulation was to be proved by comparing the simulation results and the experimental results.

• Transactions of Materials Processing
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• v.24 no.4
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• pp.256-263
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• 2015

Electric resistance spot welding has been used to join overlapped steel sheets in automotive bodies. Recently to reduce weight in automotive vehicles, non-ferrous metals are being used or considered in car bodies for hoods, trunk lids, doors parts, etc. Various welding processes such as laser welding, self-piercing rivet, friction stir welding are being used. In the current study, a new electric resistance heated friction stir spot welding is suggested for the spot welding of non-ferrous metals. The welding method can be characterized by three uses of heat -- electric resistance heating, friction stir heating and conduction heating of steel electrodes -- for the fusion joining at the interfacial zone between the two sheets. The welding process has variables such as welding current, diameter of the steel electrodes, revolutions per minute (rpm) of the friction stir pin, and the insert depth of the stir pin. In order to obtain the optimal welding variables, which provide the best welding strength, many experiments were conducted. From the experiments, it was found that the welding strength could be reached to the required production value by using an electrode diameter of 10mm, a current of 7.6kA, a stirring speed of 400rpm, and an insert depth of 0.8mm for the electric resistance heated friction stir spot welding of 5052 aluminum 1.5mm sheets.

• Journal of the Korean Graphic Arts Communication Society
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• v.25 no.1
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• pp.81-94
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• 2007

Recently, the trend in the printing industry includes shorter run lengths and with fast turnaround times. As new markets have made it possible to produce small quantities of high-quality color products at affordable price, the general commercial printing meets the customer's diverse demand by using spot color besides process four colors. Especially, by using spot color for printing the enterprise's logo or specific color, we can see the effect of printing is getting better. With the combination of the right software, ink, media, and device can be treated as a digital proofer for spot color printing, providing significant time and cost savings compared to conventional procedures. The objective of this study is to investigate the quality of spot color proofs printed by ink-jet and dye sublimation proofer using ICC-based color management system. An Epson Stylus Color 3000 ink-jet proofer combined with Best Color Proof XXL RIP was tested for glossy and matte paper. 3M Rainbow dye sublimation proofer was examined using 3M Rainbow controller ver. 4.1 RIP on the manufacturer recommended proofing paper. ICC profiles were generated for each device using ECI 2002 visual target and evaluated for the accuracy of process 4 color reproduction. The test charts consisting of Pantone color 1140 was selected to test the quality of spot color reproduction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.567-580
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• 2000

This paper proposes an integrated approach, which is independent of specimen geometry and loading type, for predicting the fatigue life of spot welded specimens. We first establish finite element models reflecting the actual specimen behaviors observed on the experimental load-deflection curves of 4 types of single spot welded specimens. Using finite element models elaborately established, we then evaluate fracture parameter J-integral to describe the effects of specimen geometry and loading type on the fatigue life in a comprehensive manner. It is confirmed, however, that J-integral concept alone is insufficient to clearly explain the generalized relationship between load and fatigue life of spot welded specimens. On this ground, we introduce another effective parameter $J_e$ composed of $J_I$, $J_{II}$, $J_{III}$, which has been demonstrated here to more sharply define the relationship between load and fatigue life of 4 types of spot welded specimens. The crack surface displacement method is adopted for decomposition of J, and the mechanism of the mixed mode fracture is also discussed in detail as a motivation of using $J_e$.