• Korean Journal of Plant Tissue Culture
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• v.21 no.2
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• pp.123-129
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• 1994

The potency of adventitious root initiation was investigated in relation with germination days and ike end of culture days healed with root induction medium on the initiation of adventitious roots from explants of soybean (Glycine max L.) cotyledon. Also, the changes in the pattern of protein profiles related with adventitious mot initiation have been examined by two-dimensional polyauyl-amide gel elecoophoresis during the germination and the initiation of adventitious roots. The potency of adventitious root initiation from germinated cotyledons was high after 4 days, and adventitious roots were initiated from after 4 days and very high after 6 days healed with mot induction medium There was a reproducible quantitative change in 34 specific protein spots during germination and adventitious root initiation. A necessary basic protein for adventitious root initiation with rotative molecular weight of 27 kD was induced during the germination. And three basic protein groups with relative molecular weight 22 kD, 23 kD and 33 kD, and two acidic protein groups with relative molecular weight 27kD and 29 kD were induced during the initiation of adventitious roots.

• Journal of The Korean Society of Grassland and Forage Science
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• v.27 no.4
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• pp.229-234
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• 2007

To select the most proper soil for root initiation from stem cuts of Birdsfoot trefoil (Lotus corniculatus L.), eight-week-old stem cuts were cultured on three types of soil [commercial bed soil, decomposed granite (DCG), and river sand] for one month. The results showed that the root initiation ratios on DCG (77.8%) and river sand (70.0%) were relatively high, but the ratio on commercial bed soil (41.1%) was very low. To examine the effect of rare earth (RE) and Indole-3-Butyric Acid (IBA) on root initiation from stem cuts of Birdsfoot Trefoil, stem cuts were cultured on two types of soil (DCG and river sand) with treatment of RE and IBA for one month. The root initiation ratios turned out to be 90.0% (DCG with 60 ppm of RE), 80.0% (river sand with 20 ppm of RE), 96.7% (DCG with 40 ppm of IBA), and 96.7% (river sand with 40 ppm of IBA). These results suggested that the most efficient way for root initiation of Birdsfoot trefoil was to culture the stem cuts on river sand or DCG over 30 days with IBA treatment (40 ppm).

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.5
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• pp.740-745
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• 1987

For the prediction of the crack growth initiation from a blunt notch or a precrack in a prestrained material under plane strain tension and small-scale yielding conditions, a microscopic fracture criterion is proposed in terms of the crack tip opening displacement(COD) needed for the attainment of fracture strain at a microstructural distance. Smooth blunting of a crack tip with an initial root radius is assumed, and strain distributions on the crack-line axis are calculated at each deformation stage until the distributions against an original distance normalized to the COD are insensitive to an initial root radius. This case of no initial-root-radius effect is taken as for a sharp crack tip, on which the criterion is applied to determine the characteristic length of material from a critical COD for a fatigue-precracked specimen. The predicted COD at the fracture initiation from a crack with an initial root radius or a prestraining shows reasonable agreement with experimental values.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.253-255
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• 2005

It has been well known that ductile fracture of steels are accelerated by triaxial stresses. The characteristics of ductile crack initiation in steels are evaluated quantitatively using two-parameters criterion based on equivalent plastic strain and stress triaxiality. The present study focuses on the effects of strength mismatching, which can elevate plastic constraint due to heterogeneous plastic straining, on critical condition to initiate ductile crack from notch root using equivalent plastic strain and stress triaxiality. In this study evaluate the criterion for ductile crack initiation in strength mismatch specimen effect of location of notch root.

• Journal of Welding and Joining
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• v.23 no.6
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• pp.87-92
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• 2005

It has been well hewn that ductile fracture of steels is accelerated by triaxial stresses. The characteristics of ductile crack initiation in steels are evaluated quantitatively using a two-parameters criterion based on equivalent plastic strain and stress triaxiality. The present study focuses on the effects of strength mismatch, which can elevate plastic constraint due to heterogeneous plastic straining, on the critical condition for ductile fracture initiation usinga two-parameter criterion. Fracture initiation testing has been conducted under static loading using notched round bar specimens which had different notch locations. This study provides the fundamental clarification of the effect of strength mismatching and effect of notch location on the critical condition to ductile crack initiation from notch root using fuite element method and ultrasonic-mechatronics system. The critical condition of ductile crack initiation from notch root of strength mismatched tensile specimens under static loading appeared to be almost the same as those of homogeneous tensile specimens with circumferential sharp notch specimen. Also, the effect of notch location in mismatched specimens was estimated using finite element(FE) analyses.

• Journal of The Korean Society of Grassland and Forage Science
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• v.21 no.1
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• pp.31-34
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• 2001

When root initiation ratio of cut Italian ryegrass (Lolium multiflorum Lam.) stems was examined in several medium conditions containing different IBA concentration, most higher root initiation ratio was confirmed at 1.0 mg/$\ell$ of IBA and the ratio was 37.5%. When cut Italian ryegrass stems were treated in cold chamber at 4$^{\circ}C$ for 40 days and incubated in growth chamber at 26$^{\circ}C$ for 1 month, the root iniation result was 0.0% at MS-0 medium, 8.3% at MS-0.5IBA medium, 37.5% at MS-1.0IBA medium, 16.7% at MS-1.5IBA medium and 12.5% at MS-2.0IBA medium.

• Journal of The Korean Society of Grassland and Forage Science
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• v.21 no.1
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• pp.35-38
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• 2001

When root initiation ratio of cut Birdsfoot trefoil (Lotus corniculatus L.) stems was examined in several medium conditions containing different IBA concentration, the higher IBA contration of medium was elucidated superior then lower IBA concentration. Highest root initiation ratio was confirmed at 2.5 mg/$\ell$ of IBA and the ratio was 90~95%. When the stems from regenerated shoots from callus were treated at 8 kinds of medium for 12 days, the root iniation result was 9 (45%) at 1/2 SH-0 medium, 10 (50%) at SH-0 medium, 10 (50%) at SH-0.5IBA medium, 10 (50%) at SH-1.0IBA medium, 13 (65%) at SH-1.5IBA medium, 14 (70%) at SH-2.0IBA medium, 19 (95%) at SH-2.5IBA medium and 14 (70%) at SH-3.0IBA medium.

• Journal of The Korean Society of Grassland and Forage Science
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• v.21 no.1
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• pp.27-30
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• 2001

When root initiation ratio of cut alfalfa (Medicago sativa L.) stems was examined in several medium conditions containing different IBA concentration, Highest root initiation ratio was confirmed at 1.0~1.5 mg/$\ell$ of IBA and the ratio was 70~75%. When the stems from regenerated shoots from callus were treated at 8 kinds of medium for 10 days, the root iniation result was 10 (50%) at 1/2 SH-0 medium, 10 (50%) at SH-0 medium, 12 (60%) at SH-0.5IBA medium, 15 (75%) at SH-1.0IBA medium, 15 (75%) at SH-1.5IBA medium. 10 (50%) at SH-2.0IBA medium, 9 (45%) at SH-2.5IBA medium and 8 (40%) at SH-3.0IBA medium.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.145-150
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• 2002

It has been well known that ductile fracture of steels is accelerated by triaxial stresses. The characteristics of ductile crack initiation in steels are evaluated quantitatively using two-parameters criterion based on equivalent plastic strain and stress triaxiality. It has been demonstrated by authors using round-bar specimens with circumferential notch in single tension that the critical strain to initiate ductile crack from specimen center depends considerably on stress triaxiality, but surface cracking of notch root is in accordance with constant strain condition. In order to evaluate the stress/strain state in the specimens, especially under dynamic loading, a thermal, elastic-plastic, dynamic finite element (FE) analysis considering the temperature rise due to plastic deformation has been carried out. This study provides the fundamental clarification of the effect of strength mismatching, which can elevate plastic constraint due to heterogeneous plastic straining, loading mode and loading rate on critical condition to initiate ductile crack from notch root using equivalent plastic strain and stress triaxiality based on the two-parameter criterion obtained on homogeneous specimens under static tension. The critical condition to initiate ductile crack from notch root for strength mismatched bend specimens under both static and dynamic loading would be almost the same as that for homogeneous tensile specimens with circumferential sharp notch under static loading.

• Journal of Welding and Joining
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• v.26 no.6
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• pp.97-102
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• 2008

It is well known that there exist two typical fatigue crack initiation locations in ship structures: one is the weld toe and the other is the weld root where partial penetration weld is performed. In particular, it is important for fillet weldments to avoid weld root cracking in order to prevent catastrophic failure particularly in ship structures. Therefore detail considerations are required for cruciform joints with partial penetration when there is a possibility of weld root crack initiation. For these reasons, fatigue tests on welded joints were performed in this study. Concept of stress intensity factor(SIF) by means of fracture mechanics is applied for predicting fatigue life of fillet welded joints.