[en] In order to trace the reaction sequence during conventional solid-state reaction in BaO-xSm₂O₃-4.5TiO₂ (0.0≤x≤1.25) system, of which the phase development process is not clearly known, different barium sources of BaCO₃ and BaTiO₃ were used as starting materials. From the analysis of X-ray powder diffraction (XRD) patterns, different secondary phases could be identified depending on the barium source used, which might mean that the equilibrium phases in BaO-xSm₂O₃-4.5TiO₂ system are very difficult to be synthesized. When BaTiO₃ was used as a raw material, because the precursor provides short diffusion paths of ions, the system revealed less secondary phases that was considered to be closer to the equilibrium state. The microwave dielectric properties of the sample used BaTiO₃ showed superiority accordingly. Microstructure and dielectric properties were examined and discussed in terms of secondary phase development

[en] Dual-function interferometer is one of interferometers that have all features of ESPI (Electronic Speckle Pattern Interferometry) and shearography in one interferometer setup. The deformation of an object is directly obtained by ESPI while the slope of the deformation of an object is obtained by shearography. If the results of shearography are divided by shearing amount and integrated by numerical analyzing, then finally the reconstructed deformation of an object that is the same as the results directly obtained by ESPI can be measured by shearography. In this study, Cu-thin plate is used as specimen and its out-of-plane deformation is measured by ESPI and shearography setup of the dual-function interferometer. Each of the results obtained by ESPI and shearography is compared by using numerical integration to the result of shearography. From this study, it is confirmed that the reconstructed deformation results obtained by numerical integration good agrees with the results obtained by ESPI.

[en] The strain distribution measurement for wall thinned pipe bends by ESPI is presented. Defect types observed in the steel piping in the Nuclear Power Plants (NPP) are the crack at the weld part and the wall thinning defect in the pipe bends. Especially, the wall thinning defects in the pipe bends due to the Flow-Accelerated Corrosion (FAC) is a main type of defects observed in the carbon steel piping system. ESPI is one of the optical non-destructive testing methods and can measure the stress and the strain distribution of the object subjected by the tensile loading or the internal pressure. In this paper, the strain distribution of the wall thinned pipe bends due to the internal pressure will be measured by ESPI technique and the results are discussed. From the results, the size of the wall thinning defect can also be measured approximately

[en] In this study, the deformation of wall thinning elbow is measured and the position of the internal thinning defect is found out by shearography. Shearography is an optical method which has applied to nondestructive testing (NDT) and the strain/stress and deformation analysis. This technique has the merit of the directly measuring the first derivative of displacement with sensitivity which can be adjusted by handling the tilt mirror in the interferometer. In this paper, we tested carbon steel pipe locally wall thinned and loaded internal pressure and the shearography was applied to measure the out-of-plane deformation of wall thinning elbow and to investigate the internal thinning defect of it. From the results, it was confirmed that this technique is proper to the practical application on the pipe line system with internal defect

[en] District Heating(DH) plant is one of major facility can be used to reduce environmental pollution. The DH pipes transmit the heat and prevent heat loss during transportation, which consists of supply and return pipes, and each pipe is operated under different temperature fluctuation condition. The objectives of this paper are to systematize data processing of transition temperature and investigate its effects on fatigue life of DH pipes. As a result, reliable fatigue life evaluation procedures as well as a relational database management system were established and successfully applied to Korean DH pipes

[en] A District Heating(DH) system supplies environmentally-friend heat and is appropriate for reduction of energy consumption and/or air pollutions. The DH transmission pipe, composed of supply and return pipes, has been used to transmit the heat and prevent heat loss during transportation. The two types of pipes are operated at a temperature of 75∼115 .deg. C and 40∼65 .deg. C, respectively, with an operating pressure of less than 1.568MPa. The objectives of this paper are to systematize data processing of transition temperature and investigate its effects on fatigue life of DH pipes. For the sake of this, about 5 millions temperature data were measured during one year at ten locations, and then available fatigue life estimation schemes were examined and applied to quantify the specific thermal fatigue life of each pipe. As a result, a relational database management system as well as reliable fatigue life evaluation procedures is established for Korean DH pipes. Also, since the prototypal evaluation results satisfied both cycle-based and stress-based fatigue criteria, those can be used as useful information in the future for optimal design, operation and energy saving via setting of efficient condition and stabilization of water temperature