• Polymer(Korea)
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• v.35 no.1
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• pp.1-6
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• 2011

Pressurized high temperature plastic resin flows into the cavity of mold and is solidified in injection molding process. Residual stress is being developed in injection molded part because of high temperature variations and high pressure. Developed residual stress relaxes as time goes. Consequently this makes part deformed and deteriorates quality of product. A measurement method of residual stress for injection molded transparent articles has been investigated using photoelasticity. Light, a composite of electromagnetic waves, is purified into a single wave by a polarized film. When this wave passes through the specimen, birefringence is developed according to the level of residual stress in the specimen and color fringed pattern appears after the second polarized film. Residual stress in the injection molded transparent flat a part has been measured quantitatively using the color fringed pattern. Optical characteristics have been a part also predicted by computer simulation and compared with experimental results.

• Animal Systematics, Evolution and Diversity
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• v.20 no.1
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• pp.31-37
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• 2004

Some hydromedusae were collected from the coasts of Seogwipo(Jejudo Island), Hoenggando Island and Ilsanhaesuyokjang(Ulsan), Korea on July 11, 1985; July 23, 1990 and July 16, 1994. They were identified into Aequorea coerulescens (Brandt, 1838) of the order Leptomedusae, and Physalia physalis utriculus La Martiniere, 1829 of the Siphonophora, respectively. The unique morphological characteristics of A. coerulescens are smooth even surface of exumbrella, large mouth with 60 highly fringed oral lobes, shallow stomach, 120 simple radial canals and flat beret-shaped bell. In P. physalis utriculus its morphological characteristics are a triangular large pneumatophore with very low or rudimentary crest, a ribbon like long slender main tentacle, siphon-shaped gastrozooid with mouth, finger-shaped dactylozooid and branched gonozooid with gonophores. P. physalia. utriculus is the Pacific form and distinguished from the Atlantic form, P. p. physalis which has a much larger pneumatophore with high crest, numerous large main tentacles, and compact arrangement of basal and ventral cormidia. As a result of this work the Korean hydromedusan fauna consists of 15 species of five orders.