• Journal of the Korean Society for Precision Engineering
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• v.29 no.1
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• pp.48-55
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• 2012

Pressure vessels in vehicle industries, power plants, and chemical industries are often affected by flaw and defect generated inside the pressure vessels due to production processes or being used. It is very important to detect such internal defects of pressure vessel because they sometimes bring out serious problems. In this paper, an optical defect detection method using digital shearography is used. This method has advantages that the inspection can be performed at a real time measurement and is less sensitive to environmental noise. Shearography is a laser-based technique for full-field, non-contacting measurement of surface deformation (displacement or strain). The ultimate goal of this paper is to detect flaws in pressure vessels and to measure the lengths of the flaws by using unwrapping, phase images which are only obtained by Phase map. Through this method, we could decrease post-processing (next processing). Real length of a pixel can be calculated by comparing minimum and maximum unwrapping images with shearing angle. Through measuring several specimen defects which have different lengths and depths of defect, it can be possible to interpret quantitatively by calculating gray level.

• Archives of Plastic Surgery
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• v.41 no.6
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• pp.673-678
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• 2014

Background The depth of graft harvest and the residual dermis available for reepithelization primarily influence the healing of split-skin graft donor sites. When the thigh region is chosen, the authors hypothesize based on thickness measurements that the anterolateral region is the optimal donor site. Methods Full-thickness skin specimens were sampled from the anteromedial, anterior, and anterolateral regions of human cadavers. Skin specimens were cut perpendicularly with a custom-made precision apparatus to avoid the overestimation of thickness measurements. The combined epidermal and dermal thicknesses (overall skin thickness) were measured using a digital calliper. The specimens were histologically stained to visualize their basement membrane, and microscopy images were captured. Since the epidermal thickness varies across the specimen, a stereological method was used to eliminate observer bias. Results Epidermal thickness represented 2.5% to 9.9% of the overall skin thickness. There was a significant difference in epidermal thickness from one region to another (P<0.05). The anterolateral thigh region had the most consistent and highest mean epidermal thickness ($60{\pm}3.2{\mu}m$). We observed that overall skin thickness increased laterally from the anteromedial region to the anterior and anterolateral regions of the thigh. The overall skin thickness measured $1,032{\pm}435{\mu}m$ in the anteromedial region compared to $1,220{\pm}257{\mu}m$ in the anterolateral region. Conclusions Based on skin thickness measurements, the anterolateral thigh had the thickest epidermal and dermal layers. We suggest that the anterolateral thigh region is the optimal donor site for split-skin graft harvests from the thigh.

• Tribology and Lubricants
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• v.31 no.1
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• pp.1-5
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• 2015

In this study, we apply an ultrasonic nanocrystal surface modification (UNSM) technique to radial journal bearings (JBs) and disks made of SUJ2 and SCM440, respectively. We investigate frictional properties of untreated and UNSM-treated specimens using a ball-on-disk tester. We construct the Stribeck curve at the boundary, under mixed and full hydrodynamic lubrication conditions for the specimens using friction data obtained from JB tests. The friction at the boundary lubrication condition and the transition period to mixed lubrication condition on the UNSM-treated specimens is reduced, which improves the service life of JBs. The major effects of this reduction in the three lubrication regimes can be explained in the terms of improved mechanical properties and the presence of micro dimples. Moreover, we estimate the friction and fatigue properties of SCM440 specimens using a ball-on-disk specimen under dry and oil-lubricated conditions. Friction test results reveal that the UNSM-treated specimens show lower friction coefficient than the untreated specimens under both dry and oil-lubricated conditions. We evaluate the fatigue properties of SCM440 specimens by calculating the Hertzian stress with respect to the failure cycles. Fatigue tests results also reveal that the UNSM-treated specimens possess a longer fatigue life than the untreated specimens. The improved properties are effective in increasing the energy efficiency of bearings.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.130-140
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• 2018

An AU-composite beam based on U-shaped steel beams and steel plate anchors of type A was developed. The composite beam reduced the height of the building floor and construction cost. In addition, it decreased the length of construction work, and improved the flexural strength and stiffness as a form of tubes. In this study, AU-composite beams were tested directly and their performance was evaluated through bending experiments. The strength of the specimens was increased initially by linear loads and reached a maximum strength due to destruction of the concrete slab. All of the experiments showed more than 85% of the maximum stress and performed gentle movement. In addition, there was good composite behavior with the steel plate anchor that had excellent composite effects and reached full strength until the maximum strength was reached. When the thickness of the steel plate was increase, the flexural stiffness and strength of the specimen were improved. Therefore, the flexural strength of AU-composite beams can be estimated using the flexural strength formula according to the KBC 2016.

• Progress in Superconductivity
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• v.5 no.1
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• pp.70-74
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• 2003

We fabricated cube textured Ni substrate for YBCO coated conductor and evaluated the effects of processing parameters on microstructural evolution and texture formation. Ni-rods as an initial specimen were prepared by two different methods, i.e., powder metallurgy(PM) and plasma arc melting(PAM). Subsequently, the rods were cold rolled to 100 $\mu\textrm{m}$ thick substrate and annealed at temperatures of $700∼1200^{\circ}C$. The texture of the substrate was characterized by pole-figure. It was observed that the texture of substrate made by P/M did not significantly varied with annealing temperature of 600∼$l100^{\circ}C$ and the full-width at half-maximums (FWHM) of both in-plane and out-of-plane were 9$^{\circ}$∼$10^{\circ}$. On the other hand, the texture of substrate made by PAM was more dependent on the annealing temperature and the corresponding values were $9^{\circ}$ ∼$13^{\circ}$ at the temperature range. In addition, recrystallization twin texture, (221)＜221＞, was formed as the temperature increased further. OM profiles showed that the grain size of substrate made by P/M was smaller than that made by PAM and this difference was correlated to the microstructure of initial specimens.

• Journal of the Korean Institute of Gas
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• v.17 no.1
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• pp.19-25
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• 2013

The joining methods of steel structures of gas facilities, bridges, ships etc. by welding are composed mostly of T-type or cruciform fillet welding and full penetration or partial penetration according to the uses and the shape of the structures. In this study, it was examined the characteristics of fatigue crack according to penetration depth in relation to material thickness in the cruciform fillet welded joints. From the results, it was investigated the safe design stresses within the range of infinite life. When the LOP length is long the range of infinite life is small with root failure and when the LOP length is short the range of infinite life is large with teo failure. For the specimen of material thickness, 20mm welded by 3 pass compared with 10mm, 15mm welded by 2 pass, the fatigue strength and the range of infinite life was more improved by increasing of notch toughness from formation of micro-ferrite acicular structure.

• Journal of Korean Society of Steel Construction
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• v.15 no.1
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• pp.25-31
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• 2003

This research aimed to experimentally and theoretically investigate the moment strength of deck plates. A moment experiment was carried out using a full-scale 14 specimen. To prevent local buckling, the point load was applied at 1/4 points. After the experiment, theoretical analysis was conducted and the differences between various codes were identified. The experimental results were compared with AISI (the American Iron and Steel Institute), EC (Euro Code) 3, and KS (Korea Standard) codes. Analysis results are summarized as follows: (1) the failure mode was influenced by local buckling at the midpoint of the beam and/or at the intermediate loading point: (2) if yielding first occurred at the tension side, the moment strength would increase as the plastic reservation of the tension zone acted: (3) the experimental results were closest to the EC3 codes in which the partial plastic reservation was considered; (4) statistical evaluation based on the EC3 Annex Z showed that the partial resistance safety coefficient calculated applying to the EC3 formula, $^{\circ}{_M}$, was placed within 1.1 which was the target value of EC3 code; and (5) the analytical power of AISI and KS codeswere expected to improve into the level of EC3 codes if the concept of plastic reservation of the tension side would be introduced to them.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.711-723
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• 2012

Structural tests were performed to investigate the structural performance of concrete-filled steel tube column using different strength steels in their flange and web with high-strength steel HSA800 and mild steel SM490, respectively. The test parameters included the strength of column flange and infill concrete, and effect of concrete infill. Connection between different grade steels were welded using the electrode appropriate for mild steel and verified its performance. To evaluate the behavior of test specimens, eccentric loading tests were performed and the results were compared with the prediction by current design codes. Axial load and moment carrying capacity of test specimens increased with the yield strength of compression flange and weld fracture occurred after the specimen shows full strength. The prediction result for axial load-bending moment relationship and effective flexural stiffness gave good agreement with the test result.

• The Korean Journal of Cytopathology
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• v.15 no.2
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• pp.101-105
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• 2004

Fine needle aspiration (FNA) cytological examination is an appropriate method for the evaluation of pulmonary nodules. In major types of lung cancer, Its diagnostic accuracy is quite high. However, it is sometimes difficult, using this technique, to differentiate between some unusual phenotypes including adenosquamous carcinoma, bronchioloalveolar carcinoma (BAC), neuroendocrine tumor, mucoepidermoid carcinoma, and sclerosing hemangioma. Here, we present a case involving extremely well differentiated adenosquamous carcinoma, mimicking benign lesions, such as pulmonary scar and adenomatoid malformation with squamous metaplasia. The patient was a 68-year-old man presenting with a solitary pulmonary nodule$(1.6\times1.6cm)$, which was incidentally found at the periphery of the right lower lobe. FNA revealed some clusters of glandular cells with minimal atypia, in addition to squamous cells at a nearly full maturational state. Histological examination verified the cytological diagnosis on a lobectomy specimen. The tumor exhibited a well differentiated adenocarcinoma component, mimicking the bronchioles in scarred lung tissue. and a well differentiated squamous cell carcinoma component, mimucking the squamous cell nests of adenoacanthoma, in the other organs. In the present case, the possibility of adenosquamous carcinoma should have been considered if squamous cells were seen in the FNA from the peripheral pulmonary nodule, even though they appeared to be benign.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.21-27
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• 2011

A nano-porous structure of tin oxide was prepared using an anodic oxidation process and the sample's electrochemical properties were evaluated for application as an anode in a rechargeable lithium battery. Microscopic images of the as-anodized sample indicated that it has a nano-porous structure with an average pore size of several tens of nanometers and a pore wall size of about 10 nanometers; the structural/compositional analyses proved that it is amorphous stannous oxide (SnO). The powder form of the as-anodized specimen was satisfactorily lithiated and delithiated as the anode in a lithium battery. Furthermore, it showed high initial reversible capacity and superior rate performance when compared to previous fabrication attempts. Its excellent electrode performance is probably due to the effective alleviation of strain arising from a cycling-induced large volume change and the short diffusion length of lithium through the nano-structured sample. To further enhance the rate performance, the attempt was made to create porous tin oxide film on copper substrate by anodizing the electrodeposited tin. Nevertheless, the full anodization of tin film on a copper substrate led to the mechanical disintegration of the anodic tin oxide, due most likely to the vigorous gas evolution and the surface oxidation of copper substrate. The adhesion of anodic tin oxide to the substrate, together with the initial reversibility and cycling stability, needs to be further improved for its application to high-power electrode materials in lithium batteries.