• Journal of Korea Port Economic Association
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• v.27 no.3
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• pp.1-12
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• 2011

The effect of real exchange rate changes on trade balance is called the J-curve effect. That is, after real depreciation, the trade balance will deteriorate in the short run and improve in the long run. Specially, import and export prices respond with little or no decline in volume. Assuming a zero initial trade balance and dominance of the exporter currency in invoicing trade contracts, the trade balance continues to deteriorate in the medium term. Over time, the relative price-induced volume effect comes to dominate the price effect and the trade balance improves. This pattern of the trade balance adjustment is commonly referred to as the J-curve effect. This study examines the effects of changes in the exchange rate on the Korean port trade balance to China. The empirical results indicate that whilst there is J-curve effect in the short-run, but in the long-run, the real depreciation of the Korean won has positive impact on port trade balance to China.

• Journal of Ocean Engineering and Technology
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• v.12 no.1
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• pp.65-75
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• 1998

The fracture resistance curve is one of most important and design techniques employed in nuclear pressure vessel structures. This study is to evaluate the J-R curve characteristics for the SA508C-3 by the unloading compliance method and load rato analysis. The effect of strain aging for the exponential correlation of the J-R curve in this metal are investigated at room temperature, 20$0^{\circ}C$ and 30$0^{\circ}C$. The load ratio analysis method can evaluate the J-R curve by using the simple tension load-displacement curve only without the repeat of the unloading and loading. Therefore, the analysis by the proposed load ratio method has a merit, in comparison with the unloading compliance method, which can measure the crack length without the precision measurement equipment.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.153-163
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• 2000

The size effect on fracture toughness was investigated by introducing $J-A_2$ theory. For this application,small size specimens were chosen to establish $J-A_2$ assessment curve with FEM analysis. Two-dimensional FEM analysis was conducted with plane strain model using ABAQUS by domain integral method to calculate both crack tip stress and fracture toughness which were used to establish $J-A_2$ curve. The assessment curve predicted the fracture toughness of large specimens very well when compared to the test values. The results showed good prediction for deep crack specimen, though there were acceptable deviations in shallow cracked specimens, presumably caused by constraint effect. When the curve applied to reactor vessel in order to predict end of life fracture toughness with assumption of on-power pressure test condition, it provided the reasonable pressure compared to the existing design value. Better predictions would be possible if more test data were available.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.2963-2971
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• 2000

In order to obtain more realistic fracture resistance curve, research is currently underway to introduce new parameter and to quantify the constraint effect. The objective of this study is to investigate the relationship between the constraint effect of a size(plane size and thickness) and the fracture resistance curve. In this paper fracture toughness tests were performed with various plane size and various thickness of specimens in two materials. The test results showed that the effects of plane size in th4 J-R curve were significant and the curve was risen with an increase in plane size. However, relatively weak influence was observed form the change of the specimen thickness and size. The stress fields near the crack tip of th specimen is close to the HRR field according to increasing the plane size and Q stress appears different value according to material properties and the plane size.

• Journal of Ocean Engineering and Technology
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• v.8 no.2
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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.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.488-503
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• 1999

The present paper considers the constraint effect on J-R curves under the two-parameter $J-A_2$ controlled crack growth within a certain amount of crack extension. Since the parameter $A_2$ in $J-A_2$ three-term solution is independent of applied loading under fully plasticity or large-scale defor-mation $A_2$ is a proper constraint parameter uring crack extension. Both J and $A_2$ are used to char-acterize the resistance curves of ductile crack growth using J as the loading level and $A_2$ are used to char-acterize the resistance curves of ductile crack growth using J as the loading level and A2 as a con-straint parameter. Approach of the constraint-corrected J-R curve is proposed and a procedure of transferring the J-R curves determined from standard ASTM procedure to non-standard speci-mens or real cracked structures is outlined. The test data(e.g. initiation toughness JIC and tearing modulus $T_R$) of Joyce and Link(Engineer-ing Fracture Mechanics 1997, 57(4) : 431-446) for single-edge notched bend[SENB] specimen with from shallow to deep cracks is employed to demonstrate the efficiency of the present approach. The variation of $J_{IC}$ and $T_R$ with the constraint parameter $A_2$ is obtained and a con-straint-corrected J-R curves is constructed for the test material of HY80 steel. Comparisons show that the predicted J-R curves can very well match with the experimental data for both deep and shallow cracked specimens over a reasonably large amount of crack extension. Finally the present constraint-corrected J-R curve is used to predict the crack growth resistance curves for different fracture specimens. over a reasonably large amount of crack extension. Finally the present constraint-corrected J-R curve is used to predict the crack growth resistance curves for different fracture specimens. The constraint effects of specimen types and specimen sizes on the J-R curves can be easily obtained from the constrain-corrected J-R curves.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.14-21
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• 2001

SG-365 steel is an important material End used for manufacturing a pressure vessel and gas piping. In this investigation, the elastic plastic fracture toughness of this material is evaluated by the unloading compliance method according to the ASTM E8l3-97 and E1152-97 method on the smooth and side groove In specimens. The effect of smooth and side groove is studied on the elastic plastic fracture toughness. The side grooved specimen is very useful in estimation of the $J_{IC}$. Because it is much easier than the smooth specimen to the onset of the ductile tearing by the R curve method. Besides. it improves the accuracy of toughness values, decreases the scattering of them and crack tunneling effect and shear lip by the side groove.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.4
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• pp.441-450
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• 1983

A reasonable J-resistance curve determination procedure is suggested by correcting the amount of overestimation in J-value whose effect becomes significant when crack grows. Experiments using compact tension specimens of an alloy steel (SCM4, K.S. Designation) are performed. The value of J estimated according to this procedure is compared with that as obtained from the method by Merkle and Corten. The conditions for J controlled crack growth proposed by Hutchinson and Paris are examined for the material used here. It appears that J resistance curve, which is independent of crack ratio can be obtained for those specimens satisfying the conditions of J controlled crack growth.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1567-1574
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• 2001

In order to operate an RPV safely it is necessary to keep the pressure-temperature (P-T) limit during the heatup and cooldown process. While the ASME Code provides the P-T limit curve for safe operation, this limit curve has been prepared under conservative assumptions In this paper the effects of conservative assumptions involved in the P-T limit curve specified in the ASME Code Sec. XI were investigated. Three different parameters the crack depth the cladding thickness and the cooling rate, were reviewed based on 3-D finite element analyses. Also the constraint effect on P-T limit curve generation was investigated based on J- T approach. It was shown that the crack depth and the constraint effect change the safe region in P-T limit curve significantly Therefore it is recommended to prepare a more precise P-T limit curve based on finite element analysis to obtain P-T limit for safe operation of an RPV.

• Journal of Ocean Engineering and Technology
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• v.15 no.3
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• pp.75-80
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• 2001

The elastic plastic fracture toughness of this material is evaluated by the an unloading compliance method according to the ASTM E813-97 and E1152-97 method on the smooth and side groove 1CT specimens. The effect of smooth and side groove is studied on the material tearing modulus and characterizes the crack tip field under the plane stress and strain. SG-365 steel is observed that J-R curve and Tmat value decrease as 0%, 20%, 30%, and 40%. The 40% side grooved specimen is very useful in estimation of the $J_IC$. Because it is much easier than the smooth specimen to the onset of the ductile tearing by the R curve method. Besides. it improves the accuracy of toughness values, decreases the scattering the them and tunneling and shear lip by the side groove. Applicability of tearing modulus($T_J$ proposed by paris et al as instability panameter for this material is investigated.