• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.5
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• pp.504-508
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• 2022

Single crystal gallium oxide (Ga₂O₃) has been an emerging material for power semiconductor applications. However, the defect distribution of Ga₂O₃ substrates needs to be carefully characterized to improve crystal quality during crystal growth. We analyzed the type and the distribution of defects on commercial (-201) Ga₂O₃ substrates to get a basic standard prior to growing Ga₂O₃ crystals. Etch pit technique was employed to expose the type of defects on the Ga₂O₃ substrates. Synchrotron white beam X-ray topography was also utilized to observe the defect distribution by a nondestructive manner. We expect that the observation of defect distribution with three-dimensional geometry will also be useful for other crystal planes of Ga₂O₃ single crystals.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.34-41
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• 1998

To oxide film, $A1_2O_3,\;Ta_2O_5$ and $ZrO_2$, coated on stainless steel (SUS410, SUS304) and pure Fe using RF magnetron sputtering method, the corrosion resistance on oxide coatings was studied using electrochemical measurement. Also, the adherence between film and substarte was studied. The adherence index ( $\chi$ ) was determined by the measure of micro hardness test. In this paper, we know that oxide film coated on SUS304 have better corrosion resistance than that coated on SUS410. In oxide film, the difference of corrosion resistance due to crystal structure have not been showed. In evaluating defect area rate of ceramic coated materials, CPCD method can be used effectively. In the micro-hardness test, with $1{\mu}m$ thickness film, it has only one the value of $\chi$. Above $2{\mu}m$ thickness film, however, get another value of $\chi$ as the cracks in film. The oxide film adhere well on the mild materials such as pure steel than high intensity materials like stainless.

• Tribology and Lubricants
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• v.31 no.3
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• pp.125-140
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• 2015

In this paper, we present the results of the wear analysis of journal bearings on a stripped-down single-cylinder engine during start-up and coast-down by motoring. We calculate journal bearing wear by using a modified specific wear rate considering the fractional film defect coefficient and load-sharing ratio for the asperity portion of a mixed elastohydrodynamic lubrication (EHL) regime coupled with previously presented graphical data of experimental lifetime linear wear in radial journal bearings. Based on the calculated wear depth, we obtain a new oil film thickness for every crank angle. By examination of the oil film thickness, we determine whether the oil film thickness at the wear scar region is in a mixed lubrication regime by comparing dimensionless oil film thickness, h/σ, to 3.0 at every crank angle. We present the lift-off speed and the crank angles involved with the wear calculation for bearings #1 and #2. The dimensionless oil film thickness, h/σ, illustrates whether the lubrication region between the two surfaces is still within the bounds of the mixed lubrication regime after scarring of the surface by wear. In addition, we present in tables the asperity contact pressure, the real minimum film thickness at the wear scar region, the modified specific wear rate, and the wear angle, α, for bearings #1 & #2. To show the real shape of the oil film at wear scar region, we depict the actual oil film thickness in graphs. We also tabulated the ranges of bearing angles related with wear scar. We present the wear volume for bearings #1 and #2 after one turn-on and turn-off of the engine ignition switch for five kinds of equivalent surface roughness. We show that the accumulated wear volume after a single turn-on and turn-off of an ignition switch normally increases with increasing surface roughness, with a few exceptions.

• Journal of Chest Surgery
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• v.17 no.1
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• pp.94-100
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• 1984

The purpose of present study is to investigate the significance of preoperative evaluation with perfusion lung scintigraphy in patients with lung cancer. Lung scans with the use of macroaggregated human serum albumin labeled with technetlum-99m were carried out in 35 patients with lung cancer before thoracotomy at Seoul National University Hospital during the period from November 1981 to September 1983. The relationship between size of the perfusion defect as seen by perfusion lung scan and size of the mass lesion as seen radiologically was correlated with the presence of regional adenopathy and resectability. Among patients with a larger perfusion defect than mass lesion on chest X-ray film.86% were found to have regional lymph node involvement with 29% resectability, whereas among patients in whom a larger defect was not present only 14% had such extension of the disease with 93% resectability. The relative pulmonary arterial perfusion of affected lung was calculated from the counts of radioactivity recorded from affected lung on both anterior and posterior scans expressed as a percentage of the total counts in the scan. The mean relative pulmonary arterial perfusion of the inoperable group [34\ulcorner%] is significantly different from both that of the pneumonectomy group [39\ulcorner%] and that of the lobectomy group [48\ulcorner%].(p<0.01)

• Journal of the Korean Society for Precision Engineering
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• v.13 no.2
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• pp.68-75
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• 1996

More accurate inspection method for facilities of nuclear power plants is required to guarantee the continuous and stable energy supply. The portion of inspection for pipes and pressure vessels is relatively big in the power plants. Conventional inspection methods using ultrasonic wave, x-ray and eddy current for nondestructive testing in nuclear power plants have been performed as the method of contact with objects to be inspected. With this reason these methods have been taken relatively much time, money and manpower. And the area to be inspected is limited by the location of probe or film. These difficulties make the inspection into a time-consuming work. We propose an optical defect detection method using phase shifting realtime holographic interferometry. This method has an advantage that the inspection can be performed at a time for relatively wide area illuminated by the laser beam, a coherent light source and can help an inspector recognize not only defects but also the high stressed areas. In this paper we show that the quantitative measurement using holographic interferometry and image processing for defect in pressure vessels is possible.

• Journal of Information Display
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• v.10 no.4
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• pp.202-205
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• 2009

An automated circuit repair system was developed for enhancing the yield of nondefective liquid crystal panels, focusing on the resist patterns on the circuit material layer of thin-film transistor (TFT) substrates prior to etching. The developed system has an advantage over the parallel conventional system: In the former, the repair conditions depend on the type of resist whereas in the latter, the repair parameters must be fine-tuned for each circuit material. The developed system consists of a resist pattern defect inspection system and a pattern repair system for short and open defects. The repair system performs fine corrections of abnormal areas of the resist pattern. The open-repair system is equipped with a syringe to dispense resist. To maintain a stable resist diameter, a thermal insulator was installed in the syringe system. As a result, the diameter of the dispensed resist became much more stable than when no thermal insulator was used. The resist diameter was kept within the target of $400{\pm}100{\mu}m$. Furthermore, a prototype system was constructed, and using a dummy pattern, it was confirmed that the system worked automatically and correctly.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.271-271
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• 2013

The defect states of a Ar-sputtered SiO2 surface on Si (001) were investigated using Auger electron spectroscopy (AES) and reflection electron energy loss spectroscopy (REELS). The REELS spectra at the primary electron energy of 500 eV showedthat three peaks at 2.5, 5.1, and 7.2 eV were found within the band gap after sputtering. These peaks do not appear at the primary electron energies of 1,000 and 1,500 eV, which means that the defect states are located at the extreme surface of a SiO2/Si thin film. According to the calculations, two peaks at 7.2 and 5.1 eV are related to neutral oxygen vacancies. However, the third peak at 2.5 eV has never been previously reported and the theories proposed that this defect state may be due to Si-Si bonding. Our Auger data showed that a peak for Si-Si bonding at 89 eV appears after Ar ion sputtering on the surface of the sample, which is consistent with the theoretical models.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.2
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• pp.166-171
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• 2016

Nickel silicide is main issue in Polycrystalline silicon Thin Film Transistor (TFT) which is made by Metal Induced Lateral Crystallization (MILC) method. This Nickel silicide acts as a defect center, and this defect is one of the biggest reason of the high leakage current. In this research, we fabricated polycrystalline TFTs with novel method called Edge Cut (EC). With this new fabrication method, we assumed that nickel silicide at the edge of the channel region is reduced. Electrical properties are measured and trap state density also calculated using Levinson & Proano method.

• Journal of Information Display
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• v.12 no.3
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• pp.121-124
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• 2011

The mechanism for lattice-shaped mura defects was proposed by characterizing the electro-optic properties of liquid crystal (LC), which showed different transmission properties between the normal and mura defect areas. An increase in the mura defect rate was observed when the dotted LC in the one drop filling (ODF) was exposed for a longer time. The dotted LC droplet at the edge evaporated more rapidly than that in the center. This resulted in a higher concentration of polar singles at the edge of the dotted LC droplet, leading to a higher ${\Delta}n$ value and higher transmittance. This implies that the reductio of the exposure time of the dotted LC to air plays a critical role in decreasing the occurrence of lattice-shaped mura defects in ODF.

• Tribology and Lubricants
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• v.23 no.4
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• pp.143-148
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• 2007

The surface defects of an aluminum tube for an OPC drum have been analyzed using a scanning microscopy(SEM) and an energy dispersive X-ray analyze.(EDX). The SEM/EDX system, which may provide good information on the surface defects and their distributions, provides an optical diameter of an impurity and a chemical composition. These are strongly related on the coated film thickness and quality of an OPC drum, which is a key element of a toner cartridge for a laser printer. The experimental results show that the local deformations, scratch wear, and flaws are produce the non-uniform coating layers, which may be removed by a manufacturing process of an aluminum tube. The major parameters on the coating quality of an OPC drum are the impurities of an aluminum tube such as silicon, oxygen, calcium, carbon, sulphur, chlorine, and others. These impurities may be removed by an ingot molding, extrusion and drawing, quality control, and packing processes with a strict manufacturing technology.