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Author

Jinyi Lee

Bio: Jinyi Lee is an academic researcher from Chosun University. The author has contributed to research in topics: Nondestructive testing & Hall effect sensor. The author has an hindex of 14, co-authored 83 publications receiving 660 citations.


Papers
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Journal ArticleDOI
TL;DR: Linearly integrated Hall sensors (LIHaS) on a wafer to minimize these waves and to improve the probability of crack detection was proposed in this paper. But, this method is not suitable for the case where the sensors are bonded at different gradients and heights on the PCB.
Abstract: Magnetic flux leakage testing (MFLT), which measures the distribution of a magnetic field on a magnetized specimen by using a magnetic sensor such as a Hall sensor, is an effective nondestructive testing (NDT) method for detecting surface cracks on magnetized ferromagnetic materials. A scan-type magnetic camera, based on the principle of MFLT, uses an inclined Hall sensor array on a printed circuit board (PCB) to detect small cracks at high speed. However, the wave forms appear in a direction perpendicular to the scan because the sensors are bonded at different gradients and heights on the PCB despite careful soldering. In this paper, we propose linearly integrated Hall sensors (LIHaS) on a wafer to minimize these waves and to improve the probability of crack detection. A billet specimen is used to determine the effectiveness of the LIHaS in multiple crack detection.

37 citations

Journal ArticleDOI
TL;DR: In this paper, a conductive silver paste for low sintering temperature was prepared by mixing two commercial silver powders with different particle size of 0.8μm and 1.6μm, and nanoparticles of 20-50nm.

37 citations

Journal ArticleDOI
TL;DR: In this article, a scan-type magnetic camera, which uses two linearly integrated Hall sensor arrays (LIHaS) on a wafer, and a small yoke-type magnetizer, which is positioned on the back of the LIHaS, is used to detect small cracks on express train wheels.
Abstract: A new and unique nondestructive testing (NDT) system able to detect a crack with high-speed and high spatial resolution, is urgently required for inspecting small cracks on express train wheels. We, in this paper, propose a scan-type magnetic camera, which uses two linearly integrated Hall sensor arrays (LIHaS) on a wafer, and a small yoke-type magnetizer, which is positioned on the back of the LIHaS. Two of the LIHaS (hereafter, differential-type LIHaS) are arrayed in parallel. The differential Hall voltages from each sensor in the scanning direction are obtained and amplified. We can achieve high-speed NDT by using the differential-type LIHaS because of the ?VH/?x value, which provides the most important crack information, can be obtained without buffering or calculation. We verified the effectiveness of this new and unique method by examination of cracks in the wheel specimen model. (A) Reprinted with permission from Elsevier.

35 citations

Journal ArticleDOI
TL;DR: In this article, a dipole model method was proposed to estimate the shape and volume of a crack on a paramagnetic metal specimen. But this method is not suitable for non-structural evaluation.
Abstract: Nondestructive evaluation (NDE) is an important methodology for quantifying cracks in engineering structures. In this paper, we propose a dipole model method (DMM) for NDE. The method is used to simulate an alternating magnetic field around a crack on a paramagnetic metal specimen and to estimate the shape and volume of the crack. This method enables faster and simpler evaluation of crack size than the traditional analytical methods. The DMM performance was verified by comparing the simulation results with the experimental results obtained using an AC-type magnetic camera.

31 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a dipole model (DM) to simulate the distribution of an alternating magnetic field around a crack on a paramagnetic material, and verified the simulation results by comparing them to the experimental results obtained by using Magneto-Optical/Eddy Current Imager system.
Abstract: A magnetic or an electrical field applied to a metallic specimen will be distributed according to the properties of the crack in the specimen. Researchers have used the finite element method (FEM) to simulate the distribution of an alternating magnetic field around a crack on a paramagnetic material. However, the simulation using this method becomes complex and time-consuming depending on the degree of accuracy desired. In this paper, we suggest a new, easier method, using dipole model (DM). The simulated results from this new method are verified by comparing them to the experimental results obtained by using Magneto-Optical/Eddy Current Imager system.

29 citations


Cited by
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Journal ArticleDOI
28 Feb 2011-Sensors
TL;DR: An overview of the fundamentals and main variables of eddy current testing is included, and the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems are described.
Abstract: Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future.

683 citations

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TL;DR: In this article, the authors reviewed the recent achievements of nanocellulose from the view point of material extraction and the composite processes to some extended important applications, including energy storage, flexible electronics, and smart materials.
Abstract: Cellulose, the chain of glucose residues easily obtained from nature, is the most common natural polymer. Owing to its own unique material properties, compared to the conventional usage, nanocellulose (NC) with a crystalline structure can be considered to be used in various industrial applications. As a novel sustainable future material, we review the recent achievements of NC from the view point of material extraction and the composite processes to some extended important applications. While the mechanical properties of NCs and the energy consumption during their composite processing are the key considerations, their application potentials have never been limited to mechanical or commodity products as conventional celluloses. In the latter part of this review, emerging engineering applications of NCs such as energy storage, flexible electronics, and smart materials will be further discussed for readers searching future high-end eco-friendly functional materials. Also some suggestions for potential applications will be also discussed.

373 citations

Journal ArticleDOI
Yan Shi1, Chao Zhang1, Rui Li1, Rui Li2, Maolin Cai1, Guanwei Jia1 
10 Dec 2015-Sensors
TL;DR: The main principles, measurement and processing of MFL data, the identification of the leakage magnetic signal is discussed, and future developments in pipeline MFL detection are predicted.
Abstract: Magnetic flux leakage (MFL) detection is one of the most popular methods of pipeline inspection. It is a nondestructive testing technique which uses magnetic sensitive sensors to detect the magnetic leakage field of defects on both the internal and external surfaces of pipelines. This paper introduces the main principles, measurement and processing of MFL data. As the key point of a quantitative analysis of MFL detection, the identification of the leakage magnetic signal is also discussed. In addition, the advantages and disadvantages of different identification methods are analyzed. Then the paper briefly introduces the expert systems used. At the end of this paper, future developments in pipeline MFL detection are predicted.

227 citations

Journal ArticleDOI
TL;DR: In this paper, the thermal expansion coefficient of the relevant alloy at the temperatures involved is investigated and a review of existing sources of data for this property is presented. And the implications of the available data and measurement techniques are discussed.
Abstract: Metallurgical operations at elevated temperatures, such as those that involve solidification and/or mechanical deformation, can be critically influenced by the thermal stresses and strains that result from expansion and contraction of the material as a function of temperature. With the increasing use of computer-based process models for these operations, there arises a greater need for quantitative data on the thermal expansion coefficient of the relevant alloy at the temperatures involved. After briefly reviewing some existing sources of data for this property, the various techniques for its measurement at elevated temperatures are then described. These include mechanical dilatometry, optical imaging and interference systems, x-ray diffraction methods and electrical pulse heating techniques. Finally the implications, for process modelling, of the available data and measurement techniques are discussed.

204 citations