Jeong-Ki Lee

Simultaneous measurements of the ultrasonic wave velocity and thickness of a solid plate made from one side of the plate

A new method is proposed for the simultaneous measurement of the ultrasonic wave velocity and the thickness of a solid plate with access from only one side. A line-contact transmitter and a line-contact receiver were placed on the same side of the specimen, and the times of flight were measured for varying distance between the transducers. The ultrasonic wave velocity and the thickness of the specimen can be simultaneously determined from the relationship between the time of flight and the ultrasonic beam path. A least-squares fitting routine was employed to increase the accuracy of the measurements. Experimental results for several specimens of different materials as well as different thicknesses show good agreement with those measured by conventional methods.

Phased array simulation for evaluation of weld in offshore chain

Offshore chain may have the flaws such as the lack of fusion in the weld. The ultrasonic testing (UT) has performed to detect the lack of fusion in the weld. The conventional UT has been performed by the pulse-echo and/or tandem method; the probe is positioned on the straight part with cylindrical surface but has not completely secured the reliability of the flaw detection in the offshore chain. Phased array ultrasonic testing (PAUT) can generate the ultrasonic focused beam and sweep the ultrasonic beam with multiple angles, so it is possible to inspect the wide area on a fixed probe position. Therefore, PAUT can inspect the full area of the weld in the offshore chain as moved with single array probe in a finite area. The phased array probe is positioned off the straight part with the spherical surface. And, the procedure of PAUT and the criteria of the detection and sizing of the flaw are not established. In this study, ultrasonic beam generated with array probe in offshore chain is simulated with CIVA simulation software, and sound pressure distribution is analyzed for establishing the criteria of the flaw sizing.

Comparison of slowness curves of Lamb wave with elastic moduli and crystal structure in silicon wafers

[100], [110] and [111] single crystal silicon wafers are employed as specimens. Varying incident angle and rotating specimen, leaky Lamb wave (LLW) from immersed wafer were detected. Analyzing signal of LLW from various propagation directions and phase velocities of each specimen, slowness curves were obtained and they showed unique symmetry with various symmetric axis. Slowness curves were compared with elastic moduli of each wafer. They showed same symmetry as crystal structures. Also, slowness curves showed expected pattern and values that can be inferred from elastic moduli. This assures that drawing slowness curve is one way to examine crystal structures of anisotropic solids. In addition, skew symmetry of slowness curve was observed for all specimens, and it requires further discussion about crystal structure of silicon crystal.

SAT0376 Predictive Significance of CCL21 and CXCL13 Levels in the Minor Salivary Glands of Patients with SjÖgren's Syndrome

Objectives Chemokines, which control inflammatory cell migration, have been shown to play important roles in the inflammatory processes associated with Sjögrens Syndrome (SS). CCL21 and CXCL13 within the lymphocytic infiltrate characteristic of the condition have been reported to contribute to ectopic lymphoneogenesis. In the current study, we investigated whether the laboratory and clinical manifestations of SS patients were associated with CCL21 and CXCL13 expression levels in the minor salivary gland. Methods We obtained sociodemographic data on a total of 106 SS patients, documented glandular and extraglandular manifestations of the disease, performed minor salivary gland biopsies, and analyzed laboratory findings. EULAR index values of SS disease activity (ESSDAI values) at the time of biopsy, and SS disease damage index (SSDDI) values, were also noted. An immunohistochemical approach was used to (semiquantitatively) measure the expression levels of CCL21 and CXCL13 in the minor salivary glands. Results The minor salivary glands of SS patients stained positively for CCL21 and CXCL13 in 46.2% (49/106) and 70.7% (75/106) of all cases, respectively. Higher-level expression of CCL21 was associated with an elevated ESR, an increased IgG level, elevated anti-SS-A and -SS-B titers, a higher focus score, and a greater ESSDAI value at the time of biopsy. Higher-level expression of CXCL13 was associated with an elevated ESR, an increased IgG level, elevated anti-SS-A and -SS-B titers, a rise in the level of rheumatoid factor, a higher focus score, and a greater ESSDAI value at the time of biopsy. In patients with extraglandular manifestations of SS, the prevalence of lymphadenopathy tended to rise with an increase in the level of CCL21. Conclusions The expression levels of CCL21 and CXCL13 within the lymphocytic infiltrates of SS patients were associated with several laboratory features of the disease, lymphadenopathy, and the extent of clinical disease activity. CCL21 and CXCL13 levels should serve as useful markers predicting SS disease activity and prognosis. Disclosure of Interest None declared

Experimental Verification and Analysis for Ability of Defect Detection with Angle for Axis Direction of Guided Wave Using Magnetostrictive Sensor

In this paper we induced it by using disperse which is wave analysis program developed by Imperial College of United Kingdom. In this paper we sent and received longitudinal mode and torisional mode of guided wave using magnetostrictive sensor for test plate of mock-up with artificial defect of 90°, 75° 60° for axis direction of pipe. We review each characteristics of each mode compare with Vpp along with angle for axis direction of received defect signal.

Safety Evaluation of Molten Steel Carrier by Using Instrument Indentation Technique

Because a molten steel carrier is used in high-temperature and corrosive environments, erosion and corrosion decrease the thickness of the structure and expand the vent hole for emitting gas generated from refractory bricks. This increases the stress throughout the structure and introduces a significant stress concentration around the vent hole. In addition, the high-temperature environment degrades mechanical properties such as the yield and tensile strengths. These problems seriously affect the safety of the structure. In this study, the safety of a 10-year-old structure was evaluated by analyzing the stress distribution and measuring the mechanical properties of the structure. The mechanical properties were directly measured on the structure surface using the instrument indentation technique.

Technique for Measurements of Elastic Wave Velocities and Thickness of Solid Plate from Access on Only One Side

A novel method is proposed for the simultaneous measurement of longitudinal and transverse wave velocities and the thickness of isotropic solid plates from access on only one side. Line contact transducers were placed on the same side of the specimen, and waveforms were acquired at various distances between the transducers. Longitudinal wave velocity and the thickness of the specimen can be simultaneously determined from the relationship between the transit time of the longitudinal wave mode and the ultrasonic beam path. A least-squares fitting method was employed to increase the accuracy of measurements. Transverse wave velocity also can be determined from the transit time of the mode-converted transverse wave and the corresponding beam path determined by Snells law. Experimental results for several specimens of different materials as well as different thicknesses show good agreement with those measured by conventional methods.