• Research in Plant Disease
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• v.29 no.3
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• pp.295-298
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• 2023

During a disease survey conducted in April 2022, we observed severe gray mold symptoms on inflorescences of mango trees (Mangifera indica) grown in a vinyl greenhouse in Jeju, Korea. The symptoms occurred on the flowers and peduncles, on which a lot of gray molds were formed. The incidence of gray mold on the inflorescences in the vinyl greenhouse ranged from 10% to 40%. Three fungal isolates were obtained from the lesions and identified as Botrytis cinerea based on their morphological characteristics and phylogenetic analysis. All isolates of B. cinerea were tested for their pathogenicity to inflorescences of mango trees through artificial inoculation. The pathogenicity of the isolates was confirmed on the flowers and peduncles. The symptoms induced by the isolates were similar to those on the inflorescences of mango trees observed in the disease survey. This is the first report of B. cinerea causing gray mold in mango in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1014-1020
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• 2012

This paper focuses on the development of a supporting S/W tool that can minimize designer's manual operations and errors in metal mold design based on a 3D solid model. The scope in this work includes the offset surface modeling, the computation of the padding force, the generation of material table, the decision of hole position, the estimation of the size of raw material, which are the essential parts of press die and mold design in automotive industry. The proposed system has been developed as a plug-in type using Pro/E API and Visual C++ in order to put the system into the menu functions of Pro/E which is one major 3D CAD systems in the manufacturing industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.554-558
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• 2006

To meet the need for trained work force from the industries, industry-oriented education for students majoring in die & mold in university level is required. If the new university graduates with creativity and high technology could be put right into the work places without training at the work sites, that will lead to remove the wasting factor in education and reinforce the competitiveness of Korea's technology power. Industries would be satisfied with the trained workforce from universities and the rate of employment will be increased. To meet the needs from industries and universities, die & mold design engineering curriculum tailored for industries is developed.

• Design & Manufacturing
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• v.13 no.4
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• pp.17-22
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• 2019

Currently, studies on weight reduction and fuel efficiency increase are the most important topics in the automotive industry and many studies are under way. Among them, weight reduction is the best way to raise fuel efficiency and solve environmental pollution and resource depletion. Materials such as aluminum, magnesium and carbon curing materials can be found in lightweight materials. Among these, research on improvement of bonding technology and manufacturing method of materials and improvement of material properties through study of ultrahigh strength steel sheet is expected to be the biggest part of material weight reduction. As the strength of the ultra hight strength steel sheet increases during forming, it is difficult to obtain the dimensional accuracy as the elastic restoring force increases compared to the hardness or high strength steel sheet. It is known that the spring back phenomenon is affected by various factors depending on the raw material and processing process. We have conducted analytical evaluations and studies to analyze the springback that occurs according to the cross-sectional shape of the ultra high tensile steel sheet.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.3
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• pp.267-273
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• 2001

In this study, the survival rate of fiber is investigated by nozzle size difference in injection/mold sides. The survival rate of fiber is influenced about the nozzle size differ. Also, The mechanical properties of short carbon glass fiber reinforced polypropylene are experimentally measured as functions of fiber volume fraction and nozzle size difference. These mechanical properties are compared with the survival rate of fiber and fiber volume fraction using image analysis after pyrolytic decomposition. The survival rate of fiber as well as fiber volume fraction is influenced by injection processing condition, the used materials, mold conditions and nozzle sides difference, etc, In particular, the survival rate of fiber is great influenced when injection/mold nozzle sides are different more than that of the same. Consequently, the mechanical properties of short carbon/glass fiber reinforced polypropylene arc improved as the nozzle sides are the same in injection mold sides.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.76-81
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• 2019

In the mold-manufacturing field, various methods of advanced production technology are being used in the production of industrial-grade gear pulleys. Among the current methods are injection molding, hoop molding, insight molding, two-material molding, compound-mold molding, as well as engineering plastic mold. Currently, casting pulleys are inexpensive because they are produced in small quantities. However, they produce complications during the manufacturing process, are very unreasonable for mass production, and are disadvantageous in cost competitiveness. Pulleys are divided into hundreds of kinds and thousands of kinds, so the production methods vary. As these pulleys are made of a single material by a casting and welding method, they are not manufactured using injection molds consisting of different materials. In this research, pulleys, shafts, and reinforced plastic materials were incorporated using ANSYS software, and a low-cost, lightweight technology was applied for trial production with optimum design and extrusion technology.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1371-1379
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• 2003

RP&M (Rapid Prototyping and Manufacturing) is the most appropriate technology for the small-lot production system, because the production cycle is getting shorter owing to various needs of the consumer. In this paper, rapid tooling technology is applied to the casting process. The casting process has the ability to reflect complicated shapes in one process. But it has not been widely used to make a die and mold because of the poor surface quality caused by air bubbles on the surface of the casting product. In this study, the porous casting mold is fabricated from a mixture of plaster and water-soluble binder. The porous casting mold can improve the characteristics of casting products with the help of the vacuum sealed casting process. The vacuum sealed casting process is an advanced technology that removes the air bubbles between the porous casting mould and the liquid metal, thus making the surface of the casting product finer. The purpose of this paper is to develop a high quality shoe mold using porous casting mold and to apply the RP&M technology to the shoe industry.

• Journal of Korea Foundry Society
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• v.29 no.5
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• pp.238-243
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• 2009

This study has been carried out to investigate the cooling ability improvement of diecasting mold by decompression cooling system. The decompression cooling system was applied to the new/used oil pump cover molds. The temperature of the surface mold applied the decompression cooling system fell to 15 degrees, especially in case of the used mold. The defect ratio of the oil pump cover manufactured by decompression cooling system has decreased from 2.8 percent to 0.2 percent. According to the results of the cooling ability improvement of diecasting mold by decompression cooling system, the decompression degree and supply pressure were set up the control item to apply the decompression cooling system to the diecasting mold in the industry field.

• Design & Manufacturing
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• v.13 no.1
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• pp.25-30
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• 2019

This paper presents the design strategy for the optimal RTM molds of Carbon Fiber Reinforced Plastic (CFRP) by carbon fiber draping and resin flow simulation. First, the mold shape and molding condition were determined considering the undercut and die face of the product in the draping simulation, which made the preliminary shape of the product by compressing the carbon fiber. After that, the diffusion behavior during the injection of resin in the mold was predicted by the resin flow simulation. Finally, the optimal mold shape was designed by selecting the locations of resin injection port and vent based on total results of simulations. In this paper, the mold of automotive side mirror case was selected as the representative product. Also, the actual mold was manufactured based on the simulation design to confirm the practicality of it. This study is expected to contribute to the industry as a technology to improve the reliability and productivity of CFRP producted by RTM process.

• Design & Manufacturing
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• v.2 no.1
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• pp.33-38
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• 2008

As consumer in optics, electronics, aerospace and electronics industry grow, the demand for ultra precision aspherical surface lens increases higher. Precision turning with single-diamond tools has a long history of development for fabrication of optical quality surfaces since the advent of aerostatic rotary spindles and precise linear motion guide ways. To enhance the precision and productivity of ultra precision aspherical surface micro lens, the following specification of ultra precision grinding system is required: the highest rotational speed of the grinder is 100,000rpm and its turning accuracy is $0.1{\mu}m$, positioning accuracy is $0.1{\mu}m$. The development process of the grinding system for the ultra precision aspherical surface micro lens for optoelectronics industry is introduced. In the work reported in this paper, an intelligent grinding system for ultra precision aspherical surface machining was designed by considering the factors affecting the surface roughness and profiles accuracy. An aerostatic form was adopted to build the spindle of the workpiece and the spindle of grinder and ultra precision LM guide way was adopted in this system. And this paper deals with mirror grinding of an aspheric surface micro lens by resin bonded diamond wheel and spherical lens of BK7. It results was that a form accuracy of $0.6{\mu}m$ P-V and a surface roughness of $0.006{\mu}m$ Rmax.