• Journal of Korea Society of Industrial Information Systems
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• v.22 no.6
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• pp.71-84
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• 2017

Over the past decade, we have witnessed Serious Debates in MISQ and Other Journals Between Two Camps that have Differing Views on the use of Causal Indicators to Measure Constructs. There is the Camp that advocates Causal Indicators (ADVOCATE) and the Camp that opposes Their Usage (OPPONENT). The Debates have been primarily centered on the OPPONENT's Argument that the Meaning of a Latent Variable is determined by its Outcome Variables. However, Little Effort has been made to Validate the ADVOCATE's Dispute (Against the OPPONENT's Arguments) that the Meaning of a Latent Variable is decided by its Causal Indicators if there is no Misspecification. Our Study precisely examines the Integrity of the Argument. For this, we empirically examine how the two Primary Psychometric Properties-Comprehensiveness and Interrelationship-of Causal Indicators Influence Theory Testing between Latent Variables through Three Different Tests (i.e., Comprehensive Test, Interrelationship Test, and Mixed Test). Conducted on Two Different Datasets, Our Analysis Consistently Reveals that Structural Path Coefficients are Hardly Sensitive to the Changes (i.e., Misspecification) in the Properties of Causal Indicators. The Discovery offers Important Evidence that the Sound Theoretical Logic of a Causal Model is not in Sync with the Empirical Mechanism of Parameter Estimation. This Underscores that a Latent Variable Formed by Causal Indicators is empirically an elusive notion that is Difficult to Operationalize. As Our Results have Significant Implications on the Integrity of Numerous IS studies which have conducted Theory or Hypothesis Testing Using Causal Indicators, we strongly advocate Open Discussions among Methodologists regarding Our Findings and Their Implications for Both Published IS Research and Future Practices.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1732-1741
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• 2020

The structural integrity of welded joints in the reactor pressure vessel (RPV) is directly related to the safety of nuclear power plants. The RPV is made from SA508-III steel in a pressurized water reactor. In this study, we investigated the effects of temperature on the tensile and fracture toughness properties of Chinese SA508-III welded joint in different sampling areas in order to provide reference data for structural integrity assessments of RPVs. The specimens used in tensile and fracture toughness tests were fabricated from the base metal (BM), weld metal (WM), and the heat-affected zone (HAZ) in the welded joint. The representative testing temperatures included the ambient temperature (20 ℃), upper shelf temperature (100 ℃), and service temperature (320 ℃). The results showed that temperature greatly affected the fracture toughness (JIC) values for the SA508-III welded joint. The JIC values for BM and HAZ both decreased remarkably from 20 ℃ to 320 ℃. The fracture morphologies showed that the BM and HAZ in the welded joint exhibited fully ductile fracture at 20 ℃, whereas partial cleavage fracture was mixed in ductile fracture mode at 100 ℃ and 320 ℃. The WM exhibited the ductile and cleavage fracture mixed mode at various temperatures, and the JIC values showed slight changes.

• Smart Structures and Systems
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• v.21 no.6
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• pp.761-776
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• 2018

Guided wave testing is a reliable and safe method for pipeline inspection. In general, guided wave testing employs a circumferential array of piezoelectric transducers to clamp on the pipe circumference. The sensitivity of the operation depends on many factors, including transducer distribution across the circumferential array. This paper presents the sensitivity analysis of transducer array for the circumferential characteristics of guided waves in a pipe using finite element modelling and experimental studies. Various cases are investigated for the outputs of guided waves in the numerical simulations, including the number of transducers per array, transducer excitation variability and variations in transducer spacing. The effect of the dimensions of simulated notches in the pipe is also investigated for different arrangements of the transducer array. The results from the finite element numerical simulations are then compared with the related experimental results. Results show that the numerical outputs agree well with the experimental data, and the guided wave mode T(0,1) presents high sensitivity to the notch size in the circumferential direction, but low sensitivity to the notch size in the axial direction.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.3
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• pp.278-286
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• 2011

The on-line monitoring for the wall thinning in secondary system has been considered one of main issues for the safety of nuclear power plants. To establish the on-line monitoring technique for the pipe wall thinning, the development of the ultrasonic transducer working in high-temperature is very important. In this investigation, the magnetostrictive transducer is concerned for high temperature condition up to $300^{\circ}C$. The magnetostrictive transducer has many advantages such as high working temperature, durability, cost-effectiveness, and shear waves, most of all. A thin Fe-Co alloy patch whose Curie temperature is over $900^{\circ}C$ was employed as a ferromagnetic material for magnetostriction. Wave transduction experiments in various temperature were carried out and the effect of bias magnets was considered together with the dry coupling performance of the transducer. From experimental results, consequently, it was found that the magnetostrictive transducer works stable even in high temperature up to $300^{\circ}C$ and can be a promising method for the on-line monitoring of the wall thinning in nuclear power plants.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.4
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• pp.321-329
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• 1998

Structural integrity of nuclear components is important for a safe operation of nuclear power plants. Therefore, nuclear power plants require to perform reliable, periodic inservice inspections. Korea Electric Power Company(KEPCO) operates the entire Korean nuclear power plants. Since nuclear power plant safety and the associated inservice inspection(ISI) are under the plant owner's responsibility, Korea Electric Power Research Institute(KEPRI), the R&D division of KEPCO, has established the ISI NDE Total Support system(TSS) for an efficient performance of ISI tasks, and initiated both key ISI NDE technology development program and traing & qualification system development program for an independent ISI operation. This paper describes details of these programs.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1051-1055
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• 2003

Aluminum carbody for rolling stocks is light and perfectly recycled, but includes severe defects which are very dangerous to fatigue strength. Structural integrity assessment for the carbody by static load test has been performed up to date. In this study, to evaluate fatigue strength of the aluminum carbody of urban transit unit. a testing method to simulate dynamic loading condition was proposed and the fatigue strength of the carbody was evaluated. The dynamic load test results showed that the alternating stress ranges were different from the estimated ranges based on the static test results. Excessive stress ranges at the center are thought to come from the flexible motion of the carbody. published fatigue test data for aluminum components, but variation of alternating acceleration along the length due to flexibility of carbody yielded unexpected results. Because fatigue strength based on the static test results may be overestimated at the center, modification of testing method is necessary.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1407-1413
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• 2011

In this paper, the structural design for composite blade was performed and full scale structural test was conducted to verify the structural design and integrity of composite blade. Firstly, FE analysis was performed using commercial software ABAQUS under conditions of rated wind speed and Case H in IEC 61400-2. Lay-up sequence and ply thickness were designed based on FE results. And to verify the structural design, full scale structural test was conducted according to IEC 61400-2 under identical loading conditions of FE analysis. Finally, the force-deflection and local strain behavior of composite blade were evaluated.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2661-2665
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• 2011

In order to evaluate the structural integrity of a GFRP composite bogie frame due to flying railway ballast, the low velocity impact test and compressive test after impact was conducted for glass fiber/epoxy 4-harness satin woven laminate composites applied to skin part of a bogie frame. The impact test was performed using a instrumented impact testing system with energy levels of 5J, 10J and 20J and the designed impactor based on typical railway ballast shapes such as sphere, cube and cone to simulate the ballasted track environments. The compressive strength was tested to according to ASTM D7137 to evaluate the degradation of mechanical property of impact damaged laminate composites. The results showed that the damage area and the degradation of compressive strength after impact for laminate composites was increased with increase in impact energy for all ballast shapes and was particularly most influenced by cone ballast shape.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.254-257
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• 2004

Fiber placement system (FPS) carries out an advanced composites process which orients high strength reinforcing fibers in specific directions. The process includes wet winding, thermoset tape winding, thermoset prepreg placement and thermoplastic prepreg placement. FPS have the advantage of tape laying and filament winding with computer control and software. Using FPS can reduce costs, cycle times, structural weight, and handwork/rework when manufacturing composite parts. The sleeve extension is a part of the helicopter rotator systems. In this study, The sleeve extension composites were manufactured using FPS and tensile properties of this composites were characterized using universal testing machine(UTM).

• Journal of the Korean Society of Safety
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• v.12 no.2
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• pp.3-16
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• 1997

In modern high performance engineering applications, the structural integrity of materials and structures are quite often evaluated using fracture mechanics. This evaluation in turn requires information on the flaw geometry (location, type, shape, size, and orientation). The ultrasonic nondestructive evaluation (NDE) method is one technique that is commonly used to provide such information. Flaw classification (determination of the flaw type ) and flaw sizing (prediction of the flaw shape, orientation and sizing parameters) are very important issues for quantitative ultrasonic NDE. In this paper new approaches to both classification and sizing of flaws are described together with extensive review of previous works on both topics. In the area of flaw classification, a methodology is developed which can solve classification problems using probabilistic neural networks, and in the area of flaw sizing, a time-of-flight equivalent (TOFE) sizing method is presented. The techniques proposed here are in a form that can be used directly in many practical applications to quantitative estimates of the flaw's significance.