• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.8 no.2
• /
• pp.86-93
• /
• 1999

Ceramic/metal bonded joints have led to increasing use of structural materials such as automobiles and heat engines. A method of strength evaluation focussing on fracture criterion of mixed mode was investigated in {{{{ {Si }_{3 } {N }_{4 } }}}}/metal bonded joint, Also Fracture toughness tests of {{{{ {Si }_{3 } {N }_{4 } }}}}/metal bonded joints with an interface crack were carried out and the stress intensity factors of these joints were analyzed by boundary element method. Form the results the fracture criterion and method of strength evaluation by the fracture toughness were proposed in {{{{ {Si }_{3 } {N }_{4 } }}}}/Metal bonded joints

• Journal of the korean Society of Automotive Engineers
• /
• v.3 no.3
• /
• pp.30-38
• /
• 1981

The fatigue characteristics of Si-Mn spring steel (AISI 9260-H, JIS SUP-6) were investigated on several heat treatment conditions. Repeated impact loads of 10kg-cm and 15kg-cm energy were applied with a cam roller drop hammer type impact fatigue testing machine. Specimens were oil-quenched, and tempered at 350.deg. C, 450.deg. C and 500.deg. C, respectively. Results obtained in these experiments are summarized as follows.; 1) The fatigue life of the specimen is decreased as the magnitude of constant impact energy is increased, regardless of heat treatment. 2) Generally, the fatigue life of the specimen is decreased as the tensile strength of the materials is increased. 3) Within the limit of these experiments, the fatigue life showed abrupt decrease at the tempering temperature of about 400.deg. C 4) The fatigue life is increased as the initial value of applied stress intensity factor(K$_{1}$) is decreased. This tendency is apparent for the low tensile strength materials.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.9
• /
• pp.1590-1596
• /
• 2016

In this paper, catenary wires were analyzed aging through the experiment about a new product and a test sample in accordance with temperature changes from long-term use. In case of the contact wire, the maximum load was reduced within 7% and the tensile strength showed a reduced within 6.7% compared with a new reference standard $110mm^2$. 19 Strands of messenger wire have a little more than a standard value, but result data on tensile test were less than the reference value about stranded wire. Also parts among 49 strands of dropper was found to be smaller than the reference value and it appeared greatly increasing intensity as toward the center of the strand.

• Advances in concrete construction
• /
• v.1 no.2
• /
• pp.121-136
• /
• 2013

Tension tests were carried out to investigate the effect of the corrosion pattern on the ductility of tension bars extracted from a 26-year-old corroded reinforced concrete beam. The tensile behavior of corroded bars with different corrosion patterns was examined carefully, as were two non-corroded bars extracted from a 26-year-old control beam. The results show that corrosion leads to an increase in the ratio of the ultimate strength over the yield strength, but reduces the ultimate strain at maximum force of the reinforcement. Both the corrosion pattern and the corrosion intensity play an important role in the ductile properties. The asymmetrical distribution of the corrosion around the surface is a decisive factor, which can influence the ultimate strain at maximum force more seriously.

• Proceedings of the KIEE Conference
• /
• 1988.11a
• /
• pp.179-182
• /
• 1988

This study is to investigate the adhesive strength of composite material's interface on the experimental methode of tree growth in the material. The results are as fellows 1) The irradiations of ultrasonic energy cause the mechanical vibration in the polymer composite materials of fluid state, so then bring about physical dispersion and heat form inorganic materials, being supposed to produce chemical crosslinking reaction, decreasing of voids between filler and matrix. 2) The characterics of the breakdown are increased by using coupling agent in the composite material. 3) As the intensity of ultrasonic energy and its irradiated time are larger, the tree inception and break-down voltages increase and the tree growing is slower. so we obtain that the interface adhesive force tan be strengthened by the irradiation of ultrasonic energy.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.10a
• /
• pp.339-343
• /
• 1995

In assessing the performance of structures such as bridges. the load intensity, load effect analysis and strength parameters are not known with certainty. The aim of structural reliability theory is to account for the uncertainties in evaluating the strength of structural systems or in the calibration of safety factors in structural design codes. The intend of structural reliability theory is to characterize these uncertainties and allow for consistent and rational safety decisions. In this study the rational model considering the live load applied to bridge will be introduced. using the structural reliability theory.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.11a
• /
• pp.224-225
• /
• 2005

The lightness of components required on marine and shipbuilding industry is requiring high strength of components. In particular, fatigue failure phenomena, which happen in metal, bring on danger in human life and property. Therefore, antifatigue failure technology takes an important part of current industries. In this study, it was investigated about endurance and fatigue crack propagation rate of according to stress ratio of SMAW commonly using for welding structures in present. Fatigue crack propagation rate(da/dN) of low load(R=0.1) was lower than of high load(R=0.6) for piping weld. And in stage I, ${\Delta}$Kth, the threshold stress intensity factor of the weld under heavy load is higher than under small load. Fatigue life shows more improvement in the weld of stress ratio R=0.l than in the weld of stress ratio R=0.6.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.17 no.1
• /
• pp.98-105
• /
• 2008

In this paper, the system for monitoring process of aluminum laser welding was developed using the light signal emitted from the plasma which comes from interaction between material and laser. Photodiode for monitoring system was selected based on the spectrum analysis of light from plasma and keyhole. Behavior of plasma and keyhole was analyzed through the sensor signals. Value of sensor signal represented the light intensity and fluctuation of signal indicated the stability of plasma and keyhole. For the relation between welding condition and sensor signals, the input power and weld geometry greatly effected on the average of each sensor signals. Using the feature values of signals, estimation model for tensile strength of weld was formulated with neural network algorithm. Performance of this model was verified through coefficient of determination and average error rate.

• Fashion & Textile Research Journal
• /
• v.11 no.3
• /
• pp.481-487
• /
• 2009

The purpose of this study is to improve the defects of dyeable polypropylene(DPP) fabric by heat setting and to describe the change of physical properties of DPP fabrics. The thermosetting was carried out in autoclave from 100 to $140^{\circ}C$ temperature range for 2 min. In this study, we investigated the effect of the thermosetting temperatures on the structural, thermal, mechanical properties(e.g., the strength and elongation) and dyeability of DPP fabrics. The melting energy(J/g), the tensile strength was found to increase with increasing temperature of thermosetting. The diffraction peak at Bragg angle($2{\theta}$) about $13.8^{\circ}$ were very strong and diffraction intensity increased with increasing thermosetting temperatures. And d-spacing and half-width decreased with increasing thermosetting temperatures. On the other hand, the dyeability(K/S) and crease recovery decreased with an increasing thermosetting temperatures.

• Journal of the Korean institute of surface engineering
• /
• v.45 no.1
• /
• pp.31-36
• /
• 2012

In order to improve the mechanical roperties of the Gangjin celadon $BaTiO_3$ was added into the raw materials of celadon matrix. Through SEM and XRD analysis the structural changes were observed and the hardness values were measured. We could confirm that the mechanical strength considerably increased in the $BaTiO_3$ added celadon through the measurement of hardness values. The increase of mechanical strength values in the celadon may result from the compositional change in the microstructure such as grain boundary area through EDAX analysis. We might suggest a fundamental idea to improve the mechanical intensity of the celadon.