• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.5
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• pp.680-688
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• 1986

In order to obtain the optimal estimation method of fracture toughness of dual phase steel in which martensitic phase encapsulated islands of ferritic phase, the stretched zone (SZ) method and the R-curve method of the JSME S 001 was discussed. The results obtained are as follows. (1) The $J_{IC}$ values estimated by the SZ method are overestimated as compared with those by the R-curve method. (2) The $J_{IC}$ by the R-curve method decreases with the increase of the ferrite grain size and the martensite hardness. (3) The overestimation of $J_{IC}$ by the SZ method is due to the continuous plastic blunting of ferrite after the formation of stable crack which affects the critical stretched zone width.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1672-1679
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• 2002

This paper provides an engineering J estimation equation for cylinders with finite internal axial surfacecracks under internal pressure. The proposed equation is the J estimation equation based on deformation plasticity using Ramberg-Osgood (R-O) materials. Based on detailed 3-D FE results using deformation plasticity, plastic influence functions for fully plastic J components are tabulated for practically interesting ranges of the mean radius-to-thickness ratio, the crack depth-to-length ratio, the crack depth-to-thickness ratio. the strain hardening index for the R-O material, and the location along the semi-elliptical crack front. Based on tabilated plastic influence functions, the J estimation equation along the crack front is proposed and validated for R-O materials. Good agreements between the FE results and the proposed J estimation provide confidence in the use of the proposed method to elastic-plastic fracture mechanics of pressurized piping.

• Journal of KSNVE
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• v.17 no.3 s.87
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• pp.4-11
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.441-442
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• 2008

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1262-1265
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• 2004

To increase the performance of the light diffusion films, we controlled the three dimensional microstructure of the organic fillers(beads). The refractive index, the size distribution and the three dimensional distribution of beads play an important role to determine the performance of light diffusion films for the backlight unit of TFT-LCD.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1398-1401
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• 1987

• 한국초전도학회:학술대회논문집
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• v.13
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• pp.66-66
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• 2003

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.3
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• pp.269-274
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• 2002

We introduce (${\tau}_i$, ${\tau}_j$) fuzzy (r,s)-semiclosures and (${\tau}_i$, ${\tau}_j$)-fuzzy (r,s)-semiinteriors. Using the notions, we investigate some of characteristic properties of fuzzy pairwise (r,s)-semicontinuous, fuzzy pairwise (r,s)-semiopen and fuzzy pairwise (r,s)-semiclosed mappings.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.171-172
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• 2006

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.57-57
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• 2004