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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society for Nondestructive Testing
Journal Basic Information
Journal DOI :
The Korean Society for Nondestructive Testing
Editor in Chief :
Volume & Issues
Volume 21, Issue 6 - Dec 2001
Volume 21, Issue 5 - Oct 2001
Volume 21, Issue 4 - Aug 2001
Volume 21, Issue 3 - Jun 2001
Volume 21, Issue 2 - Apr 2001
Volume 21, Issue 1 - Feb 2001
Selecting the target year
The Characteristics of Ultrasonic Signals for Detecting Micro-Defects in Ti-6Al-4V Alloy
Choi, Sang-Woo ; Lee, Joon-Hyun ; Kubota, M. ; Murakami, Y. ;
Journal of the Korean Society for Nondestructive Testing, volume 21, issue 6, 2001, Pages 591~597
Ti alloy is used for essential parts of aircraft for high temperature environment. Although Ti alloy has excellent performance in regard to mechanical properties, it is difficult ot find fatigue cracks by nondestructive ultrasonic inspection due to its two-phase microstructure, which consists of hard alpha and beta phases. Sound energy reflected from microstructural features in the component produces a background inspection noise which is seen even when no defects are present. This noise can inhibit the detection of critical internal defects such as pores cracks or inclusions. To obtain fundamental data on ultrasonic inspection of Ti alloy, ultrasonic testing was performed using a specimen with small drill holes and ultrasonic wave propagation velocites were measured.
Reliability Evaluation of Semiconductor using Ultrasound
Jang, Hyo-Seong ; Ha, Job ; Jhang, Kyung-Young ;
Journal of the Korean Society for Nondestructive Testing, volume 21, issue 6, 2001, Pages 598~606
Recently, semiconductor packages trend to be thinner, which makes difficult to detect defects therein. A preconditioning test is generally performed to evaluate the reliability of semiconductor packages. The test procedure includes two scanning acoustic microscope (SAM) tests at the beginning and end of the entire test, in order to help detect physical defects such as delaminations and package cracks. In particular, of primary concern are package cracks and delaminations caused by moisture absorbed under ambient conditions. This paper discusses the failure mechanism associated with the moisture absorbed and encapsulated in semiconductors, and the use SAM to detect failures such as tracks and delaminations grown during the preconditioning test.
Models of Reliability Assessment of Ultrasonic Nondestructive Inspection
Park, I.K. ; Park, U.S. ; Kim, H.M. ; Park, Y.W. ; Kang, S.C. ; Choi, Y.H. ; Lee, J.H. ;
Journal of the Korean Society for Nondestructive Testing, volume 21, issue 6, 2001, Pages 607~611
Ultrasonic inspection system consist of the operator, equipment and procedure. The reliability of results in ultrasonic inspection is affected by its ability. Furthermore, the reliability of nondestructive testing is influenced by the inspection environment, materials and types of defect. Therefore, it is very difficult to estimate the reliability of NDT due to the various factors. In this study, the probability of detection by logistic probability model and Monte Carlo simulation is used for the reliability assessment of ultrasonic inspection. The utility of the NDT reliability assesment is verified by the analysis of the data from round robin test nth these models.
Ultrasonic Characteristics of Internal Planar Defects of a Hot Forged Al-Si Alloy Part
Lee, Seok-Won ; Joun, Man-Soo ; Lee, Joon-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 21, issue 6, 2001, Pages 612~617
A nondestructive evaluation technique for detecting internal defects of an hot forged Al-Si alloy part is established in this study. Ultrasonic characteristics of various internal planar defects are investigated by experiments for establishing a reliable test procedure. The effect of the angle between ultrasonic energy propagation directions and planar defects on the ultrasonic signal configuration is evaluated in the pulse-echo technique. A characteristic of ultrasonic signal for the internal planar defect located near the edge is also evaluated. The applicability of the through-transmission technique is also discussed. Reliability of the presented approach is validated by the destructive testing for more than 500 specimens.
Reliability Estimation of High Voltage Ceramic Capacitor by Failure Analysis
Yang, Seok-Jun ; Kim, Jin-Woo ; Shin, Seung-Woo ; Lee, Hee-Jin ; Shin, Seung-Hun ; Ryu, Dong-Su ; Chang, Seog-Weon ;
Journal of the Korean Society for Nondestructive Testing, volume 21, issue 6, 2001, Pages 618~629
This paper presents a result of failure analysis and reliability evaluation for high voltage ceramic capacitors. The failure modes and failure mechanisms were studied in two ways in order to estimate component life and failure rate. The causes of failure mechanisms for zero resistance phenomena under withstanding voltage test in high voltage ceramic capacitors molded by epoxy resin were studied by establishing an effective root cause failure analysis. Particular emphasis was placed on breakdown phenomena at the ceramic-epoxy interface. The validity of the results in this study was confirmed by the results of accelerated testing. Thermal cycling test for high voltage ceramic capacitor mounted on a magnetron were implemented. Delamination between ceramic and epoxy, which might cause electrical short in underlying circuitry, can occur during curing or thermal cycle. The results can be conveniently used to quickly identify defective lots, determine
life estimation each lot at the level of inspection, and detect major changes in the vendors processes. Also, the condition for dielectric breakdown was investigated for the estimation of failure rate with load-strength interference model.
Non-destructive Reliability Evaluation of Electronic Device by ESPI
Yoon, Sung-Un ; Kim, Koung-Suk ; Jo, Seon-Hyung ; Kang, Ki-Soo ;
Journal of the Korean Society for Nondestructive Testing, volume 21, issue 6, 2001, Pages 630~633
This paper propose electronic speckle pattern interferometry(ESPI) for reliability evaluation of electronic device. Especially, vibration problem in a fan of air conditioner, motor of washing machine and etc. is important factor to design the devices. But, it is difficult to apply previous method, accelerometer to the devices with complex geometry. ESPI, non-contact measurement technique applies a commercial fan of air conditioner to vibration analysis. Vibration mode shapes, natural frequency and the range of the frequency are decided and compared with that of FEM analysis. In mechanical deign of new product, ESPI adds weak point of previous method to supply effective design information.
Fabrication Process and Reliability Evaluation of Shape Memory Alloy Composite
Lee, Jin-Kyung ; Park, Young-Chul ; Lee, Kyu-Chang ; Choi, Il-Kook ; Lee, Joon-Hyun ;
Journal of the Korean Society for Nondestructive Testing, volume 21, issue 6, 2001, Pages 634~641
Shape memory alloy has been used to improve the tensile strength of composite by the occurrence of compressive residual stress in matrix using its shape memory effect. In order to fabricate shape memory alloy composite, TiNi alloy and A16061 were used as reinforcing material and mix, respectively. In this study, TiNi/A16061 shape memory alloy composite was made by using hot press method. However, the specimen fabricated by this method had the bonding problem at the boundary between TiNi fiber and Al matrix when the load was applied to it. A cold rolling was imposed to the specimen to improve the bonding effect. It was found that tensile strength of specimen subjected to cold rolling was more increased than that of specimen which did not underwent cold rolling. In addition, acoustic emission technique was used to quantify the microscopic damage behavior of cold rolled TiNi/A16061 shape memory alloy composite at high temperature.
Environmental Testing for Precision Parts and Instruments
Choi, Man-Yong ; Park, Jeong-Hak ; Yun, Kyu-Tek ;
Journal of the Korean Society for Nondestructive Testing, volume 21, issue 6, 2001, Pages 642~649
Precision parts and instruments are tested to evaluate performance in development-process and product-step to prement a potential defect due to a failure design. In this paper, Environmental test technology, which is the basis of reliability analysis, is introduced with examples of test criterion, test method for products, encoder and traffic signal controller, and measuring instruments. Recently, as the importance of the environmental test technology is recognised. It is proposed that tranining of test technician and technology of jig design and failure analysis are very essential.
Numerical Design of Shielded Encircling Probe for RFEC Testing of Nuclear Fuel Cladding Tube
Shin, Young-Kil ; Shin, Sang-Ho ;
Journal of the Korean Society for Nondestructive Testing, volume 21, issue 6, 2001, Pages 650~657
This paper explains the process of designing a shielded encircling remote field eddy current (RFEC) probe to inspect nuclear fuel cladding tubes and investigates resulting signal characteristics. To force electromagnetic energy from exciter coil to penetrate into the tube, exciter coil is shielded outside by laminations of iron insulated electrically from each other. Effects of shielding and the proper operating frequency are studied by the finite element analysis and the location for sensor coil is decided. However, numerically simulated signals using the designed probe do not clearly show the defect indication when the sensor passes a defect and the other indication appeared as the exciter passes the defect is affected by the shape of shielding structure, which demonstrates that the sensor is directly affected by exciter fields. For this reason, the sensor is also shielded outside and this shielding dramatically improves signal characteristics. Numerical modeling with the finally designed probe shows very similar signal characteristics to those of inner diameter RFEC probe. That is, phase signals show almost equal sensitivity to inner diameter and outer diameter defects and the linear relationship between phase signal strength and defect depth is observed.
Effect of Surface Flaw Type on Ultrasonic Backscattering Profile
Kwon, Sung-D. ; Yoon, Seok-S. ;
Journal of the Korean Society for Nondestructive Testing, volume 21, issue 6, 2001, Pages 658~662
The classification of surface flaw types was performed on the basis of angular dependence of backscattered ultrasound. The copper line adhered on the surface, cower line filled in groove, pure groove and the normal edge were adopted as various surface flaw patterns of glass specimen. A backward longitudinal profile was formed probably by the longitudinal wane scattering at and near 1st critical angle. The wave trains at the peak angles of the backward radiation profiles showed different shapes according to the superposition ratio of scattered and leaky waves. The asymmetry of the backward radiation profile arose due to the scattering effect of flaw. The additive resonance effect of copper line appeared in the left side of the profile. The peak angles of both the longitudinal and radiation profiles were shifted toward small angle by the scattering effect.