• 한국안전학회지
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• 제12권3호
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• pp.45-51
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• 1997

To evaluate the elastic-plastic fracture toughness by this modified offset method, the origin of J-R curve is set with drawing the blunting line on the maximum point of the negative crack growth and R curve is modified by adding the blunting factor of the experimented point on the R curve. The elastic-plastic fracture toughness $J_{IC]$ of A5083-H112 material by the modified offset method we 44kN/m on the smooth CT specimens.

• 한국해양공학회지
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• 제8권2호
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• pp.38-46
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• 1994

The method of JSME S001-83 and ASTM E813-87 have been adapted for evaluation of the elastic-plastic fracture toughness J sub(IC) of SB41 steel. This SB41 steel have the characteristics of low-stength CT specimens. The test results obtained have been considered and compared on the basis of resulted data from two kinds of methods(JSME S001-83, ASTM E813-87) and two kinds of specimen configurations(smooth, side-grooved). On the basis of results from consideration and comparison, the difficulties for its application were presented in case when the standard ASTM E813-87 method was employed for the measurement of J sub(IC) in SB41 steel. A modified method was applied for measuring J sub(IC) in SB41 steel that it used the blunting line real-measured by experiment instead of the standard blunting line theoretically determined, and the result from that procedure was analyzed and the usefulness of that method was examined and considered.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.704-708
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• 1996

The elastic dynamic crack curving could be obtained by controlling the loading rate, the initial crack-tip blunting to store much energy before crack initiation and the magnitude of reflected wave from finite boundaries. However there is no theoretical and experimental elastic-plastic dynamic curving study. This paper proposes a specimen geometryfor a study of dynamic elastic-plastic crack curving and presents a preliminary result. The specimen has a blunt physical crack tip on a side, and a round notch tip on the other side. From the experiment using this specimen, it is found that the narrow plastic zone ahead of the round notch tip produces the change of load direction and anti-symmetricity of the dynamic isochromatics, and each result causes the crack curving phenomenon. After a certain time, as the elastic-plastic crack gets close to the round notch tip near, the degree of the crack curving get larger. The elastic reack curving propagates more sensitively to the surround of crack tip than the plastic crack curving does. The cynamic elastic-plastic crack curving is found to be proportional to the CTOA(the crack tip opening angle). The dynamic elastic-plastic crack may propagate in the direction perpendicular to the loading. An apparant strip yield zone which is similar to the Dugdale strip yield zone is noted ahead of the physical crack tip.

• 대한기계학회논문집
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• 제13권4호
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• pp.653-659
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• 1989

본 연구에서는 실험방법과 해석방법 등의 차이가 Ｊ$_{IC}$ 값에 미치는 영향을 고찰하여 보았으며, E 813-81법으로 해석된 Ｊ$_{IC}$ 값으로 환산하는 방법을 제안하고 몇 가지 재료와 환경에서 그 오차를 검토하였다.하였다.

• 한국해양공학회지
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• 제7권2호
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• pp.91-102
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• 1993

The elastic-plastic fracture thoughness J sub(IC) of Nuclear Reactor Vessel Steel(SA 508-3) which has high toughness was discussed at temperatures RT, $-20^{\circ}C$, $200^{\circ}C$ and 1/2/CT specimen was used for this study. Especially the two methods recommended in ASTM and JSME were compared. It was difficult to find J sub(IC) by ASTM R-curve method with the specimen used for this research, while JSME R-curve method yielded good result. The stretched zone width menthod gave slightly larger J sub(IC) values than those by the R-curve method for SA 508-3 steel.

• 대한기계학회논문집
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• 제9권5호
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• pp.564-571
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• 1985

본 논문에서는 미시조직인자를 변화시킨 마르텐사이트-페라이트 복합조직강을 준비하여 균열선단 및 안정영역의 파괴양상과 파괴저항과의 관계를 검토하였다.

• 한국해양공학회지
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• 제8권2호
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• pp.157-165
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• 1994

Effect of an accelerated iso-thermal aging (375 degree C x 66days, 375 degree C x 200days) on elastic-plastic fracture resistance curve were examined in SA533B low alloy steel. Fracture toughness test are conducted by unloading compliance method at room temperature. But the apparent negative crack growth phenomenon, usually arise in partial unloading compliance test. The phenomenon of negative crack growth may be eliminated by the offset technique. There is no effect of aging on J sub(IC) and dJ/da in iso-thermal aged (375 degree C x 66 days) specimen, but there is very little effect in iso-thermal aged (375 degree C x 200 days) specimen.

• 한국해양공학회지
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• 제9권1호
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• pp.111-119
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• 1995

The elastic-plastic fracture toughness($J_{IC}$) and fracture resistance (J-R curve) of SA508-3 alloy steel used for nuclear reactor pressure vessel are investigated by using CT-type specimens. Fracture toughness tests are conducted by unloading compliance method and multiple specimen method at room temperature, -2$0^{\circ}C$ and 20$0^{\circ}C$. The apparent negative crack growth phenomenon which usually arises in partial unloading compliance test is well known. The negative crack growth phenomenon in determining J sub(IC) or J-R cure from partial unloading compliance experiments may be eliminated by the offset technique. In this study, the evaluation of $J_{IC}$ multiple specimen method recommended by the JSME gives the most reliable results by using half-size CT(similar-type) specimens.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.238-243
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• 2000

The effect of the temperature, the fatigue and the test speed on DEN(double edged notch) specimen which was made by the pp-rubber composites during fracture was stuied. DEN specimen was made on PP-rubber composites through the injection molding. With increasing temperature the fracture strength is linearly decrease and the fracture energy is first increase by $0^{\circ}C$ and after that decrease. In the same temperature the fracture strength during increasing the notch radius is hardly increase. The fracture behaviour at low and high test speed is different entirely. At high test speed plastic region is small and fracture behaviour was seen to brittle fracture tendency. The deformation mechanism of polypropylene-rubber composites during fracture was studied by SEM fractography. A strong plastic deformation of the matrix material ahead of the notch/crack occured. The deformation seem to be enhanced by a thermal blunting of the notch/crack.

• 대한두경부종양학회지
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• 제39권2호
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• pp.23-26
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• 2023

Lower lip reconstruction in cases with a full-thickness defect over one-third of the vermilion is challenging. Numerous conventional techniques have been applied with unsatisfactory surgical outcomes because of microstomia and oral commissure blunting due to shortened horizontal lip length. Herein, we present a case in which a full-thickness lower lip defect of more than one-third of the horizontal lip length was covered with a novel mucosal roofing flap reconstruction to minimize the loss of horizontal lip length and to preserve mouth opening. No recurrences or metastases were observed during 3 years and 6 months of follow-up, with horizontal lower lip length maintained and mouth opening of 2.5 finger breadths.