• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.2
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• pp.179-185
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• 2000

The purpose of this study was to develop an osteogenic, biodegradable material using polymer and BMP. It was designed to have structural function and be moldable, for the reconstruction of load bearing areas and deformities of various configurations. Bone apatite was added to Poly(L-lactide)(PLLA) and made porous for osteoconductability and ease of BMP loading. The materials, with or without BMP purified from porcine bone matrix, were evaluated in cranial bone defect models in rats for biocompatibility and bone regeneration capability. The following results were obtained: The PLLA-BMP material with BMP added to the polymer showed 30% healing of cranial bone defects in rats during the 2 weeks to 3 months period of observation. The moldable PLLA agent without BMP also showed 25% bone healing capacity. Although new bone formation was incomplete in the critical size defect of rat cranium, it can be concluded that the unique moldability of those agents makes them useful for the reconstruction of various bone defects and maxillofacial deformities.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.05a
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• pp.48-64
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• 2002

The primary recognized health risk from common deficiencies in glucose-6-phosphate dehydrogenase (G6PD), a cytoprotective enzyme for oxidative stress, is red blood cell hemolysis. Here we show that litters from untreated pregnant mutant mice with a hereditary G6PD deficiency had increased prenatal (fetal resorptions) and postnatal death. When treated with the anticonvulsant drug phenytoin, a human teratogen that is commonly used in pregnant women and causes embryonic oxidative stress, G6PD-deficient dams had higher embryonic DNA oxidation and more fetal death and birth defects. The reported G6PD gene mutation was confirmed and used to genotype fetal resorptions, which were primarily G6PD deficient. This is the first evidence that G6PD is a developmentally critical cytoprotective enzyme for both endogenous and xenobiotic-initiated embryopathic oxidative stress and DNA damage. G6PD deficiencies accordingly may have a broader biological relevance as important determinants of infertility, in utero and postnatal death, and teratogenesis.-Nicol, C. J., Zielenski, J., Tsui, L.-C., Wells, P. G. An embryoprotective role for glucose-6-phosphate dehydrogenase in developmental oxidative stress and chemical teratogenesis.

• Industrial Engineering and Management Systems
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• v.9 no.3
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• pp.251-261
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• 2010

This article demonstrated the application of the Fuzzy Data Envelopment Analytical Hierarchy Process (FDEAHP) to evaluate the root causes of critical defect problems occurring in the production of liquid medicine. The methodology of the research began by collecting the defect data by using Check Sheets, and ranking the significant problems by using a Pareto Diagram. Two types of major problems were found to occur, including glass fragments in the medicine and damaged lid threads. The causes of each problem were then analyzed by using Cause and Effect Diagrams. The significant causes were ranked by FDEAHP under three criteria, Severity (S), Occurrence (O) and Detection (D), followed by the framework of the FMEA Technique. Two causes with the highest Final Weight (FW) of each problem were selected to be improved, such as installing auxiliary equipment, using the Poka-Yoke system, setting the scale of the shaft and lathing the bushes of each bottle size. The results demonstrated a reduction in defects from 3.209% to 1.669% and showed that improving a few significant root causes, identified by an experienced decision maker, was sufficient to reduce the defect rate.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.1
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• pp.40-45
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• 2019

Unlike the welded pipes in the primary system of light water nuclear power plants being periodically inspected with in-Service inspection program, relatively small pipes with the outer diameter less than 2 inch have not been regularly inspected to date. However, after several failure reports on the occurrence of critical crack-like defects in small pipes, inspection for the small pipes has been more demanded because it could cause the provisional outage of nuclear power plants. Nevertheless, there's no particular method to examine the small pipes having access limitations for inspection due to various reasons; inaccessible area, excessive radiation exposure, hazardous surrounding, and etc. This study is to develop a reliable inspection technique using torsional and flexural modes of guided wave to detect defects that could occur in inaccessible area. The attribute of guided wave that can travel a long distance enables to inspect even isolated range of the pipe from accessible location. This paper presents a case study of the evaluation test on 3/4" small-bore pipes with guide wave method. The test result demonstrates the crack signal behavior and assures possibility to detect the crack signal in a flexural mode, which is clearly distinguishable from the symmetric structure signal in a torsional mode.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.117-122
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• 2019

Pipes are widely used in various industries such as automobile, anti-vibration devices, factories and ship building. Chamfering is one of the most critical processes in pipe manufacturing which removes burrs of the pipes for better surface quality. In most cases, the defects of the chamfered surface are originated from the structural vibrations of the chamfering machine. In this study, the dynamic characteristics of a chamfering machine have been analyzed though the experiment and the computer simulation. And the effects of the design parameters affecting the stability of the machine have been investigated to stabilize the machine structure and further to reduce structural vibrations. The result shows that design alterations to stabilize the machine can suppress the defects of the machined surface as well as the vibrations during chamfering.

• BMB Reports
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• v.56 no.4
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• pp.240-245
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• 2023

Glial cells play important roles during neurogenesis and in maintaining complex functions of the nervous system. Here, we report the characterization of a gene, Sdr, which contains a putative insulin-like growth factor receptor domain and is required to maintain critical nervous system functions in Drosophila. Sdr is expressed in glial cells during embryonic and larval stages of development, but its role in adult flies is poorly understood. As insulin signaling is important throughout the lifespan in human, we investigated the Sdr's role in adult flies. Our results demonstrate that Sdr is expressed on surface glial cells that surround the nervous system. Mutation of Sdr did not affect development but caused defects in locomotion and lifespan. Sdr mutants also showed increasingly severe defects in the blood-brain- and blood-retina-barriers as they aged. Therefore, we suggest a novel role of Sdr in maintaining the integrity of the blood-brain- and blood-retina-barriers in adult flies.

• Journal of Ocean Engineering and Technology
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• v.27 no.3
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• pp.61-66
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• 2013

This paper presents the results of finite element simulations of elastic wave propagation in an underwater steel plate and the verification of a proposed method utilizing elastic wave-based damage detection. For the simulation and verification, we carried out the following procedures. First, three-dimensional finite element models were constructed using a general purpose finite element program. Second, two types of damages (mechanical defects and deteriorations) were applied to the underwater steel plate and three parameters (defect location, defect width, and depth) were considered to adjust the severity of the applied damages. Third, elastic waves were generated using the oblique incident method with a Gaussian tone burst, and the response signals were obtained at the receiving point for each defect or deterioration case. In addition, the received time domain signals were analyzed, particularly by measuring the magnitudes of the maximum amplitudes. Finally, the presence and severity of each type of damage were identified by the decreasing ratios of the maximum amplitudes. The results showed that the received signals for the models had the same global pattern with minor changes in the amplitudes and phases, and the decreasing ratio generally increased as the damage area increased. In addition, we found that the defect depth was more critical than the width in the decrease of the amplitude. This mainly occurred because the layout of the depth interfered with the elastic wave propagation in a more severe manner than the layout of the width. An inverse analysis showed that the proposed method is applicable for detecting mechanical defects and quantifying their severity.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.6
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• pp.591-597
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• 2001

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.

• Progress in Superconductivity and Cryogenics
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• v.22 no.3
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• pp.7-12
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• 2020

Electromechanical properties of REBCO CC tapes are known to be limited by defects (cracks) that form in the brittle REBCO layer. These defects could be inherently acquired during the CC tapes' manufacturing process, such as slitting, and which can be initiated at the CC tapes' edges. If propagated and long enough, they are believed to cause critical current degradation and can substantially decrease the delamination strength of CC tapes. Currently, commercially available CC tapes from various manufacturers utilize different growth techniques for depositing the REBCO layers on the substrates in their CC tapes preparation. Their epitaxial techniques, unfortunately, cannot perfectly avoid the formation of particles, in which sometimes acts as current blocking defects, known as outgrowths. Collective research regarding the composition, size, and formation of these particles for various CC tapes with different deposition techniques are particularly uncommon in a single study. Most importantly, these particles might interact in one way or another to the existing cracks. Therefore, systematic investigation on the interactions between the cracks' development mechanism and particles on the REBCO superconducting layers of practical CC tapes are of great importance, especially in the design of superconducting devices. Here, a proper etching process was employed for the CC tapes to expose and observe the REBCO layers, clearly. The scanning electron microscope, field emission scanning microscope, and energy-dispersive x-ray spectroscopy were utilized to observe the interactions between cracks and particles in various practical CC tapes. Particle compositions were identified whether as non-superconducting or superconducting and in what manner it interacts with the cracks were studied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.352-357
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• 2020

This study was performed to solve the quality problems of forging propeller shaft components in the marine diesel engines during the final cooling process and provide reasonable guidelines to increase the production of forging products. Residual hydrogen existing on the inside of forging products begins to diffuse and accumulates at the pores, micro-fissures, and grain boundaries as the temperature of forging products begins to decrease and reaches a critical temperature range, and finally transforming into internal defects. These defects were easily found near the surface of products after milling the surface of forging products. In this work, four types of forging products (shaft flange, shaft journal, thrust shaft, and propeller shaft) were chosen to evaluate the temperature history of products during the cooling process, employing non-linear numerical analyses with the ANSYS program. The times elapsed to reach 250 ℃ after cooling were approximately 9 ~ 23 hours for each forging product. These times can be used as cooling process guidelines on the quality and productivity of products after heat treatment.