• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.1
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• pp.58-64
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• 2003

A mechanical press joining was investigated in ender for joining A1-5052 sheets for automobile body weight reduction. Static tensile and fatigue tests were conducted using tensile-shear specimens for evaluation of fatigue strength of the joint. During Tox joining process for A1-5052 plates, using the current sheet thickness and punch diameter, the optimal applied punching force was found to be 32 kN under the current joining condition. For the static tensile-shear experiment results, the fracture mode is classified into interface fracture mode, in which the neck area fractured due to influence of neck thickness, and pull-out fracture mode due to influence of plastic deformation of the joining area. And, during fatigue tests for the A1-5052 tensile shear specimens, interface failure mode occurred in the region of low cycle. The fatigue endurance limit approached to 6 percents of the maximum applied load, considering fatigue lifetime of $2.5\times10^6$ cycles.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.607-610
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• 2004

It is still not sufficient for the famous embedded software test methods such as Finite State Machine, Software Cost Reduction and model coverage based test case generation, to pinpoint where bugs hang around and to figure out what makes the bugs. A new approach to ameliorate the drawbacks is proposed in this paper. In the approach, we define a generic model for embedded software. And we also define failure mechanism for embedded software, and a way to generate test cases based on it.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.396-401
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• 1995

Epoxy coated reinforcing steels (ECRs) were acquired from ten sources and coatings from each source were initially characterized in terms of defects, thickness, solvent extraction weight loss and hardness. Testing involved exposure in three aqueous solutions at elevated temperature (8$0^{\circ}C$) and in chloride-contaminated concrete slabs under outdoor exposure, It was found that the density and size of coating defects was the promary factor affecting ECR performance. The equivalent circuit analysis using electrochemical impedance spectroscopy (EIS) data indicated that the impedance response for well-performing ECR specimens showed no signs of active degradation at the interface although diffusional processes similar to those noted for poorly performing bars occurred here. Experimental results also indicated a relationship between corrosion behavior and bar source. Weight loss upon solvent extraction correlated with impedance reduction from hot water exposure. Coating defects during most of the tests, especially in high pH solutions containing chloride ions. ECRs with excessive coating defects, either initially present or ones which developed in service, performed poorly in every test category regardless of source. Forms of coating failure were extensive rusting at defects, blistering, wet adhesion loss, cathodic delamination, underfilm corrosion and coating cracks. These occurred sequentially or concurrently, depending on the condition of the ECR and nature of the environment

• Journal of Applied Tourism Food and Beverage Management and Research
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• v.9
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• pp.273-302
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• 1998

INTERNATIONAL MONITORY FUNDS wave swept the Economic structural insolvency lies one upon another with low growth, low trust, low prices, low interest and low employment as[2 down 3 up] phenomenons have been distinguished and low enterprise a control of structures due to forecasting 200 million unemployment, including 600 million unemployed the head of a family population have a difficulty in their life. Only way to give them hope is through the commencement of an enterprises to have 2nd career development. But end of 1995, 467,00 dining out companies have been established and recently business are in depression. There are many business conditions of change of business or reduce operations, if unemployment populations of 5%, 100,000 peoples doing the commencement of an enterprises, enormous number of dining out companies will be increased and the competition will be fierce, especially those who have short knowledge and experience doing the commencement of an enterprises have high failure than success which will give a problems to society. Our study is to make the commencement of an enterprise to reducing the faiure and to be successful for main point to successful commencement of an enterprise, the established can self capability and mental condition, the main important factor is types of industry selection, successful and those established who takes this conditions will very carefully inspect various matters by scientifically and rationally mind industrys propulsion graphs and open official fixture graphs will framing detail factors. One by inspect the reduction of failure, and successful commencement of an enterproses mind industry have been studied.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.4
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• pp.395-401
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• 2017

Energy absorption capabilities and failure modes of circular tubes made of glass/epoxy with two trigger mechanisms were evaluated. Three types of glass/epoxy tubes were fabricated using a hand lay-up method with unidirectional and woven fabric prepregs tapes, and a filament winding method. The one end of the fabricated tubes was machined for the bevel trigger and tulip trigger. Then, crush tests were conducted at 10 mm/min loading speed, wherein the glass/epoxy tubes were crushed by a brittle fracturing mode combined with fragmentation and lamina-splaying modes. The UD glass/epoxy tubes with a bevel trigger and the filament winded tubes with a tulip trigger showed the maximum and minimum specific energy absorptions, respectively, with a difference of 9.3%. The tube with a tulip trigger exhibited a maximum reduction of 5.7% in the initial peak load; the tube with a bevel trigger showed a maximum increase of 2.9% in the specific energy absorption.

• Journal of Astronomy and Space Sciences
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• v.15 no.2
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• pp.459-473
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• 1998

As the satellite system becomes more complex, the probability of unpredictable failures may be increased due to design inadequacy, experience deficiency, lack of problem recognition. Poor quality control, improper testing, and workmanship fault. Consequently, these problems can lead to the reduction or end of the satellite mission lifetime. This article addresses general satellite failure modes and factors influencing satellite mission life. The mission life factors of LEO sun-synchronous KOMPSAT spacecraft are investigated, in which its mission life is predicted based on these factors. Since the end of mission due to random failures is not predictable, the predictable mission life factors such as power budget, propellant budget, battery charging/discharging cycle, radiation effects payload reliability, single point failure, and redundancy are primarily investigated.

• Structural Engineering and Mechanics
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• v.66 no.4
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• pp.445-452
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• 2018

In this paper the effects of particle size and model scale of concrete have been investigated on point load index, tensile strength, and the failure processes using a PFC2D numerical modeling study. Circular and semi-circular specimens of concrete were numerically modeled using the same particle size, 0.27 mm, but with different model diameters of 75 mm, 54 mm, 25 mm, and 12.5 mm. In addition, circular and semi-circular models with the diameter of 27 mm and particle sizes of 0.27 mm, 0.47 mm, 0.67 mm, 0.87 mm, 1.07 mm, and 1.27 mm were simulated to determine whether they can match the experimental observations from point load and Brazilian tests. The numerical modeling results show that the failure patterns are influenced by the model scale and particle size, as expected. Both Is(50) and Brazilian tensile strength values increased as the model diameter and particle sizes increased. The ratio of Brazilian tensile strength to Is(50) showed a reduction as the particle size increased but did not change with the increase in the model scale.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.6
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• pp.291-299
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• 2014

There has been an increasing demand for introducing a base isolation system to secure the seismic safety of a nuclear power plant. However, the design criteria and the safety assessment methodology of a base isolated nuclear facility are still being developed. A performance based design concept for the base isolation system needs to be added to the general seismic design procedures. For the base isolation system, the displacement responses of isolators excited by the extended design basis earthquake are important as well as the design displacement. The possible displacement response by the extended design basis earthquake should be limited less than the failure displacement of the isolator. The failure of isolators were investigated by an experimental test to define the ultimate strain level of rubber bearings. The uncertainty analysis, considering the variations of the mechanical properties of isolators and input ground motions, was performed to estimate the probabilistic distribution of the isolator displacement. The relationship of the displacement response by each ground motion level was compared in view of a period elongation and a reduction of damping. Finally, several examples of isolator parameters are calculated and the considerations for an acceptable isolation design is discussed.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.27-36
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• 2013

LEM (Limit Equilibrium Method) based programs are commonly used for the designs of soil nailing as a slope reinforcement. However, there is a drawback that the interaction between ground and soil nailing is not properly reflected in those programs, which needs to be solved. For economical constructions and designs, research is also required on the support pattern of soil nailing. In this study, therefore, reinforcement effects of soil nailing were compared and analyzed by performing finite difference analyses which could properly consider the interaction between ground and soil nailing. As a result, when the angle from slope to nail is $90^{\circ}$, failure slip surface becomes the largest and thus the factor of safety becomes maximum.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.9
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• pp.915-923
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• 2007

Rubber hoses for automobile radiators are apt to be degraded and thus failed due to the influence of contacting stresses of air and coolant liquid under thermal and mechanical loadings. The aging behaviors of the skin part of the hoses due to thermo-oxidative and electro-chemical stresses were experimentally analyzed. Through the thermo-oxidative aging test, it was shown that the surface hardness IRHD(International Rubber Hardness Degrees) of the rubber increased with a considerable reduction of failure strain as the aging time and temperature increased. On account of the penetration of coolant liquid into the skin part influenced by the electro-chemical degradation(ECD) test the weight of the rubber hose increased, whereas their failure strain and IRHD hardness decreased. The hardness of the hose in the side of the negative pole was the most deteriorated at the test site of the hose skin just below the coolant surface.