• Annals of Clinical Neurophysiology
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• v.9 no.2
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• pp.43-50
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• 2007

Analysis of intraepidermal nerve fibers using skin biopsy is a recently developed technique, providing diagnostic information on small fiber neuropathies. The specimens are obtained by 3 mm punch biopsy, which is safe and minimally invasive. Immunohistochemical staining by Protein gene product (PGP) 9.5 demonstrate not only intraepidermal nerve fibers but dermal structures, such as sweat gland and erector papillae. Up to now, many studies agree that intraepidermal nerve fiber density is dramatically reduced in various sensory neuropathies. The utility of density measure was confirmed with high sensitivity in the diagnosis of sensory neuropathy, comparable to sural nerve biopsy or quantitative sensory testing. Besides quantitative methods, morphological changes like axonal swelling and fragmentation can be used as predegenerative markers. This article reviews the technique of skin biopsy and clinical and experimental usefulness of skin biopsy in diagnosing and monitoring peripheral neuropathies.

• Geomechanics and Engineering
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• v.24 no.4
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• pp.337-348
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• 2021

Brillouin Optical Frequency Domain Analysis (BOFDA) is a distributed fiber optic sensing (DFOS) technique that has unique advantages for performance monitoring of piles. However, the complicated production process and harsh operating environment of offshore PHC pipe piles make it difficult to apply this method to pile load testing. In this study, sensing cables were successfully pre-installed into an offshore PHC pipe pile directly for the first time and the BOFDA technique was used for in-situ monitoring of the pile under axial load. High-resolution strain and internal force distributions along the pile were obtained by the BOFDA sensing system. A finite element analysis incorporating the Degradation and Hardening Hyperbolic Model (DHHM) was carried out to evaluate and predict the performance of the pile, which provides an improved insight into the offshore pile-soil interaction mechanism.

• Restorative Dentistry and Endodontics
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• v.45 no.4
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• pp.43.1-43.9
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• 2020

A variety of therapeutic modalities can be used for the endodontic treatment of a traumatized tooth with internal root resorption (IRR). The authors present a case report of the successful restoration of a traumatized upper central incisor that was weakened due to severe IRR and subsequent periapical lesion formation. A 20-year-old female patient was referred to our clinic with severe internal resorption and subsequent periapical pathosis destroying the buccal bone wall. Root canal treatment had been initiated previously at another dental practice, but at that time, the patient's condition could not be managed even with several treatments. After cone-beam computed tomography imaging and proper chemomechanical cleaning, the tooth was managed with a mineral trioxide aggregate plug followed by root canal filling using short fiber-reinforced composite, known as the Bioblock technique. This report is the first documentation of the use of the Bioblock technique in the restoration of a traumatized tooth. The Bioblock technique appears to be ideal for restoring wide irregular root canals, as in cases of severe internal resorption, because it can uniquely fill out the hollow irregularities of the canal. However, further long-term clinical investigations are required to provide additional information about this new technique.

• Composites Research
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• v.17 no.1
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• pp.47-54
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• 2004

Vacuum hot pressing has been used for the development of titanium metal matrix composites using foil-fiber-foil technique. Subsequent micro-mechanical characteristics of the composites are then investigated by means of several experimental methods. The levels of consolidation, together with mechanism based failure processes of the materials have been analyzed by employing a thermo-acoustic emission technique. As shown by the results, fiber strength degradation occurs during the consolidation, and particularly residual stresses results from the thermal expansion mismatch between fiber and matrix materials during cooling process are incorporated in the changes of mechanical properties of the finished products. In industrial applications, both qualitative and quantitative evaluations of the material-mechanical characteristics are particularly important, and therefore must be included in process development. The present paper represents a methodology by which this can be achieved.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.2
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• pp.275-282
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• 2002

Tensile residual stress happen by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite(MMC). In this study, TiNi fiber was used to solve the tensile residual stress as the reinforced material. TiNi fiber improves the tensile strength of composite by occurring compressive residual stress in matrix using shape memory effect of it. Pre-strain was added to generate compressive residual stress inside TiNi/A16061 composite. It was also evaluated the effect of compressive residual stress corresponding to pre-strains variation. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain difference of TiNi/A16061 shape memory alloy composite.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.104-108
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• 2004

A simple dispersion measurement technique has been demonstrated by using a self-seeding laser oscillation of a Fabry-Perot laser through a closed loop. The optical pulses of different wavelengths emitted from the Fabry-Perot laser travel down an optical fiber and the group velocity difference between the pulses due to the chromatic dispersion of the optical fiber is measured through the self-seeding laser oscillation process. The dispersion parameter of the optical fiber is calculated from the measured group velocity difference. The performance of the proposed technique has been confirmed experimentally and the accuracy of dispersion parameter measurement was comparable to that of commercial instruments with expensive equipment and components. The repeatability of the proposed method was better than 0.5%.

• Smart Structures and Systems
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• v.14 no.3
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• pp.307-325
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• 2014

A newly developed method based on energy is presented to study the damage pattern of FRP material. Basalt fiber reinforced polymer (BFRP) is employed to monitor the damage under fatigue loading. In this study, acoustic emission technique (AE) combined with scanning electronic microscope (SEM) technique is employed to monitor the damage evolution of the BFRP specimen in an approximate continuous scanning way. The AE signals are analyzed based on the wavelet transform, and the analyses are confirmed by SEM images. Several damage patterns of BFRP material, such as matrix cracking, delamination, fiber fracture and their combinations, are identified through the experiment. According to the results, the cumulative energy (obtained from wavelet coefficients) of various damage patterns are closely related to the damage evolution of the BFRP specimens during the entire fatigue tests. It has been found that the proposed technique can effectively distinguish different damage patterns of FRP materials and describe the fatigue damage evolution.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.2
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• pp.157-167
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• 1994

This study was conducted to analyze the relationship between the types of fiber and its content and the levels of airborne fiber concentrations at eight parking lots where sprayed insulation material was found on the walls and ceilings. Also this study was designed to find the relationship between the levels of airborne fiber concentrations and such variables as air current, humidity, total exhaust volume, surface condition of insulation material and building age. The results obtained were as follows : 1. No significant correlation was found between the levels of airborne tiber concentration and the building age, air current, humidity, total exhaust volume, space and the number of traffics. 2. A significant correlation was found between the levels of airborne fiber concentration and the MMMF content of the insulation material(r=0.7594). However, no significant correlation was found between the levels of airborne fiber concentration and total fiber content of insulation material. 3. The differences of the airborne fiber concentrations among Cateogory 1, 2 and 3 classified by the degrees of surface insulation material maintenance were very significant. 4. Two bulk samples contained 30% crodicolite and 1% anthophylite. The MMMFs, in all parking lots, included mineral wool, cellulose fiber, trace cellulose fiber, trace tiber glass and vermiculite. 5. The mean value and the range of airborne fiber concentrations at 8 parking lots were $0.0239{\pm}0.0095f/cc$ and 0.0054-0.0447 f/cc, respectively. The fiber concentrations of 35 out of 38 samples(92%) were over 0.01 f/cc which is the Environment Administration's recommended asbestos level for the underground space. This study suggests that most of building insulation materials used in Korea, contain MMMF and sometimes asbestos. Currently, MMMF pollution levels may exceed the Environment Administration's recommended level for underground space. It has been found that airborne fiber concentrations increased significantly with MMMF content and with the maintenance condition of surface material. Therefore, it is recommended that a proper management technique should be developed and immediately implemented since the conditions of surface material will be gradually deteriorated due to building age and usage. Since health hazards of the MMMF, similar to those of asbestos, are being gradually acknowledged, a proper management technique which is applicable to control total airborne fiber concentrations, both asbestos and MMMF, be developed and an acceptable indoor air standard be promulgated as early as possible.

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.372-373
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• 2004

• Proceedings of the Korean Fiber Society Conference
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• 1993.06b
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• pp.173-177
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• 1993