• Journal of the Korean Institute of Gas
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• v.4 no.1 s.9
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• pp.33-39
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• 2000

Stress intensity factor after penetration was discussed experimentally using long surface pre-cracked specimens of aluminum alloy 5083. The propagation behavior evaluation of long surface crack by equation proposed at penetration of short surface crack could be need modification to evaluate precisely because the error was high as aspect ratio is little. The modification of stress intensity factor with consideration of aspect ratio at penetration of long surface crack can be analyzed the behavior of crack penetration quantitatively.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.852-858
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• 2012

This paper describes evaluation results of the wind power penetration limit (WPPL) and the wind energy penetration (WEP) in the Mongolian central power system (MCPS). A wind power plant (WPP) in a power system possesses an output power limit because the power system must maintain a balance between the generation and consumption of electricity at all times in order to achieve an adequate level of quality. The instantaneous penetration limit (IPL) of wind generation at a load is determined as the minimum of the three technical constraints: the minimum output, the ramp rate capability, and the spinning reserve of the conventional generating units. In this paper, a WPPL is defined as the maximum IPL divided by the peak load. A maximal variation rate (VR) of wind power is a major factor in determining the IPL, WPPL, and WEP. This paper analyzes the effects of the maximal VR of wind power on the WPPL, WEP, and capacity factor (CF) in the MCPS. The results indicate that a small VR can facilitate a large amount of wind energy while maintaining a high CF with increased wind power penetration.

• Journal of Ocean Engineering and Technology
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• v.8 no.1
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• pp.41-49
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• 1994

The leak-before-break(LBB) design on the large structures such as ship's hull, tank structure, pressure vessels etc. is one of the most inportant subjects for the evaluation and the assurance of safety. In these structures, various loads are acting. In some structural members, therefore, out-of-plane stress due to bending often may become with in-plane stress due to stretching. In the present report, the characteristics of fatigue life and peneration behaviour from a surface cracked plate under combined tension and bending have been studied experimentally and analytically by using eccentricity. Estimation of fatigue crack growth was done with the Newman-Raju formula before penetration, and with the stress intensity factor after penetration proposed by the author. Calculated aspect ratio showed the good agreement with the experimental result. It was also found that particular crack growth behaviour and crack shape after penetration can be satisfactorily evaluated using the K solution proposed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.848-852
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• 2007

Many numerical analysis tools for predicting penetration speed of sheet pile are thought to be unreliable because they overestimate penetration speed for shallow depth of penetration. In order to overcome the defects of numerical analysis, lateral vibration model of sheet pile was suggested and energy consumption due to lateral vibration of sheet pile was estimated. Also, load reduction factor which explains reduction of vibratory driving force due to lateral vibration was introduced.

• International Journal of Korean Welding Society
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• v.3 no.1
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• pp.8-16
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• 2003

A major concern in Gas Metal Arc (GMA) welding process is the determination of welding process variables such as wire diameter, gas flow rate, welding speed, arc current and welding voltage and their effects on the desired weld bead dimensions and shape. To successfully accomplish this objective, 81 welded samples from mild steel AS 1204 flats adopting the bead-on-plate technique were employed in the experiment. The experimental results were used to develop a mathematical model to predict the magnitude of bead geometry as follows; weld bead width, weld bead height, weld bead penetration depth, weld penetration shape factor, weld reinforcement shape factor, weld bead total area, weld bead penetration area, weld bead reinforcement area, weld bead dilution, length of weld bead penetration boundary and length of weld bead reinforcement boundary, and to establish the relationships between weld process parameters and bead geomery. Multiple regression analysis was employed for investigating and modeling the GMA process and significance test techniques were applied for the interpretation of the experimental data.

• Korean Journal of Computational Design and Engineering
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• v.18 no.5
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• pp.367-373
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• 2013

In this study, the penetration characteristic from the cubic and cylindrical penetrator consisting of tungsten material with the velocity of 2,300 m/s is evaluated and the penetration possibility into the target is confirmed. The design of shape and size of penetrator is directly related to space and weight of the warhead. AUTODYN-3D simulation is used to study the penetration effect of penetrator. The purpose of numerical analysis is to verify the penetration characteristic with various L/D penetrator. The penetration performance of penetrator with identical weight due to the shape is also confirmed. The cylindrical and cubic penetrator has enough penetration energy on constant target body. Because the possibility of 2'nd penetration is important factor after 1'st penetration into target body, residual velocity of residual mass must be existed as much as possible. As geometrical shape ratio increases, penetration performance is confirmed to improve.

• Advances in concrete construction
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• v.7 no.2
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• pp.75-85
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• 2019

The present study is focused on the mechanical and durability properties of ternary blended cement concrete mix of different grades 30 MPa, 50 MPa and 70 MPa. Three mineral admixtures (fly ash, silica fume and lime sludge) were used as a partial replacement of cement in the preparation of blended concrete mix. The durability of ternary blended cement concrete mix was studied by exposing it to acids HCl and $H_2SO_4$ at 5% concentration. Acid mass loss factors (AMLF), acid strength loss factor (ASLF) and acid durability factor (ADF) were determined, and the results were compared with the control mix. Chloride ions penetration was investigated by conducting rapid chlorination penetration test and accelerated corrosion penetration test on control mix and ternary blended cement concrete. From the results, it was evident that the usage of these mineral admixtures is having a beneficiary role on the strength as well as durability properties. The results inferred that the utilization of these materials as a partial replacement of cement have significantly enhanced the compressive strength of blended concrete mix in 30 MPa, 50 MPa and 70 MPa by 42.95%, 32.48% and 22.79%. The blended concrete mix shown greater resistance to acid attack compared to control mix concrete. Chloride ion ingress of the blended cement concrete mix was low compared to control mix implying the beneficiary role of mineral admixtures.

• Journal of the Korea Computer Industry Society
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• v.9 no.3
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• pp.137-142
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• 2008

The major influence factor on chloride penetration into concrete structures is chloride ion concentration. In this study, chloride penetration analyses with chloride ion concentration were carried out by the developed program. Also, the service life of concrete structures was predicted. The penetration depth was 32mm in case that chloride ion concentration wad 600ppm. It was shown that the service life of concrete structures with 40mm cover depth was 167 years even though they had been exposed at chloride ion concentration 600ppm during 100 years.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.29-38
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• 1997

Crack penetration behavior by fatigue crack propagation and measurements of AE before-and-after crack penetration were examined using SS41 steel plate. Experimental crack shape of SU type was in good agreement with calculated shape rather than S type. Crack propagation behavior on the front surface appears not to change markedly after penetration. However, crack growth on the back surface appears to accelerate as reported by author. As a crack propagates, AE occurred heavily just before penetration. Then, it decreases and crack is penetrating. A transition from plane strain to plane stress was observed by fractographic study. At this time, separation of fracture surface was shown which affects AE occurrence.

• Journal of Korean Society of Steel Construction
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• v.10 no.3 s.36
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• pp.497-508
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• 1998

The objective of this study is to examine fatigue behavior of as-welded butt-welded joints with incomplete penetration from fatigue tests. The test results are the following. In static tests, tensile strength and yield strength of butt-welded joints are constant regardless of incomplete penetration. And in fatigue tests, fatigue strength of fully penetrated butt-welded joints satisfies fatigue limits, prescribed in Korean Specifications and JSSC, respectively. The results show that as the magnitude of incomplete penetration increases, fatigue strength decreases. In fractured surfaces, full and incomplete penetration specimen show different shapes, it is because that stress concentration factor vary with structural geometry in bead toe and root tip, and certify in FEM analysis. This study suggests that defects such as incomplete penetration from welding must be avoided in order to attain the sufficient life of steel structures.