• Computational Structural Engineering
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• v.6 no.3
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• pp.113-123
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• 1993

Most of the ship structures and offshore structures are constructed through the welding and they are always subjected to variable loads. In this study, fatigue and stress concentration of the various types of welding connections due to the variable loads are investigated by using numerical approach, and comparisons between numerical analysis and experiments are performed. Fillet weld, full penetration weld and partial penetration weld characteristics are studied by using parameters such as penetration length, welding leg length, size and penetration angle. Based on this study, it is suggested that the fillet welding can be replaced with the penetration welding in some cases. The results of this study can be used as guidelines for actual welding problems in the shipyards.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.248-253
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• 2000

This paper presents parametric study of long-rod penetration. Influences of yield stress of penetrator and target material on the penetration results such as crater size and penetrator residual length are contemplated. Numerical experiments are carried out with varying the value of static yield stress of materials. Lagrangian explicit code NET2D was used to perform parametric study. Element eroding algorithm was used to properly simulate long-rod penetration. Analytic and empirical model of long-rod penetration and Taylor test are used to explain the relationships of parameter and simulation results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.384-394
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• 2005

Important characteristics of impinging sprays intersected by a strongly convective gaseous cross flows were experimentally investigated. The breakup processes due to different Weber and Reynolds numbers of liquid and gas streams were visually examined with quantitative measurements of breakup lengths, penetration heights, and droplet sizes. Snapshot images and spay data evidenced that, at lower jet Reynolds number the breakup processes portrays the atomization profiles similar to typical column breakup of single orifice jet. At higher jet Reynolds numbers, disintegration of jet stream is significantly expedited by strong momentum transported from strongly convective gaseous stream. The breakup length and penetration height decreased as the convective flow increase. From the bottom the wall up, the SMD measured the centerline increase. The maximum SMD appeared the top of the SMD distribution

• Journal of Mechanical Science and Technology
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• v.16 no.1
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• pp.24-31
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• 2002

The leak-before-break (LBB) behaviors of a structural component under high and low fatigue loads are an important problem in nuclear power plants, liquid nitrogen gas tankers and chemical plants. This paper is an experimental study to evaluate the crack opening behavior after penetration for plate and pipe specimens. Crack opening displacement after penetration under low fatigue load could be satisfactorily determined at the center of the plate thickness regardless of the specimen size. In the case of high fatigue load, it is shown that the crack opening displacement at the center of a penetrated crack carl be derived using the gross stress, $\sigma$/sug G/, and the front surface crack length, a$\_$s/, together with the back surface crack length, a$\_$b/.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.395-406
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• 2005

Important characteristics of swirl sprays intersected by a strongly convective gaseous cross flows were experimentally investigated. The breakup processes due to different Weber and Reynolds numbers of liquid and gas streams were visually examined with quantitative measurements of breakup lengths, penetration heights, and droplet sizes. Snapshot images and spray data evidenced that, at lower jet Reynolds number the breakup processes portrays the atomization profiles similar to typical column breakup of single orifice jet. At higher jet Reynolds numbers, disintegration of jet stream is significantly expedited by strong momentum transported from strongly convective gaseous stream. The breakup length and penetration height decreased as the convective flow increase. From the bottom the wall up, the SMD measured the centerline first increases and then decreases before again increasing.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3852-3859
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• 2021

This paper presents experimental and numerical analysis results regarding the effects of an incomplete penetration defect on the fatigue lives of socket welded pipes. For the experiment, four-point bending fatigue tests with various defect geometries (defect depth and circumferential length) were performed, and test results are presented in terms of stress-life data. The results showed that for circumferentially short defects, the fatigue life tends to increase with increasing crack depth, but for longer defects, the trend becomes the opposite. Finite element analysis showed that for short defects, the maximum principal stress decreases with increases in crack depth. For a longer defect, the opposite trend was found. Furthermore, the maximum principal stress tends to increase with an increase in defect length regardless of the defect depth.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.129-130
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• 2004

The stainless steel sheet which is one of primary barrier components for membrane on LNG ship is ordinarily welded by either TIG or PAW. The weld shapes of acceptant tolerance for membrane construction are scripted by G.T.T.(Gaztransport ＆ Technigaz)‘s rules such as penetration depth, weld throat and weld length etc. This paper presents relationship between weld metal shear strength and weld penetration formed with plasma arc welding. The results show penetration depth is not decisive factor on shear strength, but weld throat and length.

• Journal of the Korean Wood Science and Technology
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• v.39 no.3
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• pp.252-257
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• 2011

Tests were carried out on domestic wood samples to modify the formula which had previously been developed to predict the withdrawal strength of screw on the face of lumber. Screw sizes were No. 6, 8 and 10 used in this study. Predicted equations were fitted to the results of different length of No. 8 wood screw. The withdrawal strength of screws was enabled to predicted as a function of screw diameter, depth of penetration, and specific gravity of wood. Predicted equation was under-predicted the withdrawal strength of 25 and 30 mm length of screw within 5% and over-predicted withdrawal strength of 18 and 38 mm length of screw.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.5
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• pp.550-556
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• 2012

In this study, a series of ballistic experiments have been performed to investigate the protection mechanism of some inert reactive cassettes against shaped charge jet. Three kinds of material were tested as a core material of the inert cassettes, i.e. one of rubber materials, a high modulus and high strength composite material used for ballistic protection and a mixture of energetic materials. Parameters such as deformation of the cassettes, occurrence time of jet distortion, leading jet length and residual penetration depth were investigated from the experiments and they were compared to each other quantitatively according to the jet incidence angles. The results show that the increment of cassette deformation caused jet distortion to occur early and jet distortion brought decrease of the length of leading jet. Then the decrease of the length of leading jet accompanied the decrease of residual penetration depth.

• Journal of the Korea Furniture Society
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• v.26 no.2
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• pp.179-185
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• 2015

A study was carried out to observe the 1% aqueous safranine solution flow speed in longitudinal and radial directions of softwood G. biloba, ring-porous wood A. altissima, and diffuse- porouswood D. kaki. In radial direction, ray cells and in longitudinal direction tracheids, vessel and wood fiber were considered for the measurement of liquid penetration speed at less than 12% moisture contents (MC). The length, lumen diameter, pit diameter, end wall pit diameter and the numbers of end wall pits determined for the flow rate. The liquid flow in the those cells was captured via video and the capillary flow rate in the ones were measured. Vessel in hardwood species and tracheids in softwood was found to facilitate prime role in longitudinal penetration. Radial flow speed was found highest in ray parenchyma of G. biloba. Anatomical features like the length and diameter, end-wall pit numbers of ray parenchyma were found also responsible fluid flow differences. On the other hand, vessel and fiber structure affected the longitudinal flow of liquids. Therefore, the average liquid penetration depth in longitudinal tracheids of G. biloba was found the highest among all cells considered in D. kaki and A. altissima.