• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.399-406
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• 1990

This paper is studied to know corrosive wear mechanism of STS304 steel on atmospherical temperature against mating material as the same. The corrosive test was carried out by rubbing the annular surface of two test pieces in distilled water and NaCl aqueous solution. The corrosive wear mechanism was investigated by S.E.M. The experimental results show that there is one Lcr transferring from severe wear to mild wear on change of NaCl concentration and atmospherical temperature, and which is the other still remaining in server wear state. It was found that the critical sliding distance Lcr shorten with increasing NaCl concentration but it is longer with ascending atmospherical temperature and the mild wear state still continues under the condition of high generation rate and elimination rate of the corrosive product. Considering upon the result, the model of corrosive wear mechanism is proposed.

• Proceedings of the KWS Conference
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• 2003.05a
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• pp.193-195
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• 2003

Micro-structure and shear properties with reflow conditions, reflow temperature and time, for In-48Sn solder on BGA package were examined at the temperature between 140 and 170$^{\circ}C$ for 10 to 3600sec. With increasing reflow temperature and time, the thickness of intermetallic compound formed between solder and pad increased. Shear test indicated shear force increased in the range to a critical value of reflow time, and decreased over a critical reflow time. With increasing reflow temperature and time, the crater occurred on fracture surface because of a increase of crater by voids and IMC particles precipitated in solder.

• 전기의세계
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• v.23 no.6
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• pp.49-55
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• 1974

Amorphous semiconductor from As 30 Te 48 Ge 10 Si 12 was prepared, and studied electron microscopy, X-ray analysis and resistivity measurement. It's resistivity is 1.56*10$^{6}$ .ohm.-cm when small ampule is used for preparing sample it is found that no phase separation has occurced by electron microscopy, and that phase transition temperature is 232.deg. C by differential Thermal Analysis. The specimen showed threshold switching that the low resistance state occur at critical electric field and the resistance recover at low applied field. Critical electric field of the switching is 10$^{5}$ V/cm at room temperature. Threshold voltage secreace exponentially with increasing ambient temperature and at that each voltage resistance of the switching device increase exponentially. According to the series resistance and applied vottage current slope on the V-I curve is varied. When applied voltage is decreased after switching, the resistance of the switching device is increased. By this result the origin of the switching is the Joule's heating.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.1061-1067
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• 2005

The resonant frequency modulation of $YBa_2Cu_3O_{7-x}$ meander lines has been investigated as functions of optical pulse energy and temperature by using a network analyzer. The frequency-domain measurements are performed by controlling both the resonant frequency and the frequency width. The meander lines, configured in a microstrip geometry, are illuminated by optical pulses from an actively mode-locked Nd:YAG laser. The variation of the resonant frequency shows a quadratic dependence on the reduced optical pulse energy $P/P_c$, where $P_c$ is defined as the critical optical pulse energy at which resonance signal has disappeared. As for the dependence on temperature, the results are in good agreement with the previously reported data.

• Journal of Korean Association for Spatial Structures
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• v.4 no.1 s.11
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• pp.87-95
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• 2004

This paper shows the study on the capacity of H-shape column at elevated temperature in fire. The main parameters are temperatures, slenderness ratios and load ratios. The physical properties of steel material at elevated temperatures are according to EC3 Part 1.2. The critical temperature of local buckling at elevated temperatures are lower when the yield strength of the material is higher, and when the ratios of width-thickness of plates are larger. The evaluation capacity of uniformly heated steel cloumns were considered to axial forces, moments of strong axis and weak axis to the LRFD.

• Steel and Composite Structures
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• v.9 no.2
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• pp.89-101
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• 2009

This paper presents a simplified model to study post-buckling behaviours of the axially restrained steel column at elevated temperatures in fire. The contribution of axial deformation to the curvature of column section is included in theoretical equations. The possible unloading at the convex side of the column when buckling occurs is considered in the stress-strain relationship of steel at elevated temperatures. Parameters that affect structural behaviours of the axial restrained column in fire are studied. The axial restraint cause an increase in the axial force before the column buckles; the buckling temperature of restrained columns will be lower than non-restrained steel columns. However, the axial force of a restrained column decreases after the column buckles with the elevation of temperatures, so make use of the post-buckling behaviour can increase the critical temperature of restrained columns. Columns with temperature gradient across the section will produce lower axial force at elevated temperatures.

• Steel and Composite Structures
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• v.12 no.2
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• pp.129-147
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• 2012

In this paper, the thermal buckling analysis of rectangular composite laminated plates is investigated using the Differential Quadrature (DQ) method. The composite plate is subjected to a uniform temperature distribution and arbitrary boundary conditions. The analysis takes place in two stages. First, pre-buckling forces due to a temperature rise are determined by using a membrane solution. In the second stage, the critical temperature is predicted based on the first-order shear deformation theory. To verify the accuracy of the method, several case studies were used and the numerical results were compared with those of other published literatures. Moreover, the effects of several parameters such as aspect ratio, fiber orientation, modulus ratio, and various boundary conditions on the critical temperature were examined. The results confirm the efficiency and accuracy of the DQ method in dealing with this class of engineering problems.

• Steel and Composite Structures
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• v.46 no.5
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• pp.637-647
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• 2023

Nonlinear free vibration and stability responses of a carbon nanotube reinforced composite beam under temperature rising are investigated in this paper. The material of the beam is considered as a polymeric matrix by reinforced the single-walled carbon nanotubes according to different distributions with temperature-dependent physical properties. With using the Hamilton's principle, the governing nonlinear partial differential equation is derived based on the Euler-Bernoulli beam theory. In the nonlinear kinematic assumption, the Von Kármán nonlinearity is used. The Galerkin's decomposition technique is utilized to discretize the governing nonlinear partial differential equation to nonlinear ordinary differential equation and then is solved by using of multiple time scale method. The critical buckling temperatures, the nonlinear natural frequencies and the nonlinear free response of the system is obtained. The effect of different patterns of reinforcement on the critical buckling temperature, nonlinear natural frequency, nonlinear free response and phase plane trajectory of the carbon nanotube reinforced composite beam investigated with temperature-dependent physical property.

• Tribology and Lubricants
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• v.9 no.1
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• pp.16-21
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• 1993

A method has been developed to measure the surface temperature in a sliding tribosystem. The determination of the surface temperature was inferred from the temperature of hot spots which were generated by frictional heat. The temperature of hot spots was determined by regressing those digitized data on Gecim-Winer's theoretical model. The experimental results are discussed considering the important factors such as PV and frictional heat. The surface temperature rise is related to the thermal conductivity in low PV range. As PV increases, it reaches nearly constant value called the critical temperature.

• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.43-43
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• 2008