• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.269-275
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• 2000

The fretting wear characteristics of TiN coated Zircaloy-4 tube were investigated experimentally The fretting wear experiment was performed using TiN coated Zircaloy-4 tube as the fuel rod cladding material and uncoated Zircaloy-4 tube as one of grids. TiN coating is probably one of the most frequently and successfully used PVD coatings for the mitigation of fretting wear. In this study, TiN coating by PVD was employed for improvement of Zircaloy-4 tube fretting characteristics. The fretting tester was designed and manufactured for this experiment. TiN coated Zircaloy-4 tube was used as the moving specimen, uncoated ZircaBoy-4 tube as the stationary one. The number of cycles, slip amplitude and normal load were selected as main factors of fretting wear. The results of this research showed that the wear volume of TiN coated Zircaloy-4 tube increased as number of cycles, normal load and slip amplitude increase but the quantity of volume was lower than the case of uncoated Zircaloy-4 tube pairs.

• Steel and Composite Structures
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• v.21 no.2
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• pp.429-442
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• 2016

The aim of this paper is to determine temperature and stress distributions in a ceramic based on Partially Stabilized Zirconia coated steel piston crown by using plasma spraying for improving performance of a marine diesel engine. Effects of coating constituent and thickness on temperature and stress distributions were investigated including comparisons with results from an uncoated piston by means of finite element method namely ANSYS. Temperature developed at the coated surface is significantly higher than that of the uncoated piston. The maximum stress components occur between bond coat and adjacent ceramic layer. Provided that coating thickness is constant as 0.5 mm, when numbers of layers increase, magnitude of the normal stress decrease about 34.1% on the base metal surface according to uncoated piston, but the base metal surface temperature of the steel piston increase about 13.1%.

• Applied Microscopy
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• v.42 no.3
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• pp.147-150
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• 2012

A recently introduced helium ion microscopy (HIM) was employed to observe uncoated pine leaf specimens. Adult leaves were collected from the seedlings of Pinus densiflora and P. rigida, air-dried at room temperature, and observed by HIM without metal coating. Ovoid or round stomata and distinct Florin rings could be discerned. The epicuticular waxes were present in the epistomatal chambers and Florin rings of stomata on the leaf surface. The epicuticular waxes were mostly straight, cylindrical, and ca. 1 ${\mu}m$ in length. The epistomatal chambers of P. rigida were filled with the epicuticular waxes, whereas those of P. densiflora were not filled with the epicuticular waxes. Based on their micromorphology, the epicuticular wax structures of the pine species were identified as tubules. These results suggest that the HIM could be used for the investigation of the plant stomata and epicuticular waxes of uncoated plant leaves. Due to the smaller ion probe and interaction volume, the HIM has advantages over conventional field emission scanning electron microscopy in terms of image resolution and charge neutralization.

• BMB Reports
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• v.31 no.4
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• pp.384-390
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• 1998

DNA fragments (51-587 bp) were separated by capillary electrophoresis using entangled polymer, hydroxyethylcellulose, in uncoated fused silica capillary columns. The factors affecting the separation of DNA fragments with hydroxyethylcellulose media were evaluated, i.e., the concentration of buffer and entangled polymer, effects of additives (methanol, ethidium bromide, EDTA), temperature, and injection methods. Maximum performance was obtained by adding 5% methanol in 0.5% hydroxyethylcellulose solution at $30^{\circ}C$. Addition of methanol in polymer media increased the resolution of small size DNA fragments (< 100 bp). On the other hand, addition of ethidium bromide and EDTA, which are commonly used in conventional DNA separation, reduced the resolution of DNA fragments in the polymer solution. It turns out that the separation behavior of DNA in entangled polymer is more sensitive to the running condition compared to that in polyacrylamide gel-filled capillary, but the reproducibility of DNA separation in entangled polymer is reliable.

• Journal of the Semiconductor & Display Technology
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• v.14 no.2
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• pp.47-52
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• 2015

In this paper, the performance of uncoated- and Titanium nitride aluminium TiAlN-PVD coated- carbide twist drills were investigated when drilling aluminium alloy, Al 6061. This research focuses on the optimization of drilling parameters using the Taguchi technique to obtain minimum surface roughness and thrust force. A number of drilling experiments were conducted using the L9 orthogonal array on a CNC vertical machining center. The experiments were performed on Al 6061 material l blocks using uncoated and coated HSS twist drills under dry cutting conditions. Analysis of variance(ANOVA) was employed to determine the most significant control factors. The main objective is to find the important factors and combination of factors influence the machining process to achieve low surface roughness and low cutting thrust force. From the analysis of the Taguchi method indicates that among the all-significant parameters, feed rate are more significant influence on surface roughness and cutting thrust than spindle speed.

• Tribology and Lubricants
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• v.11 no.5
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• pp.66-70
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• 1995

In this investigation, a controlled-environment tribological test device has been used to study the friction coefficients of several grades of commercially-available coated and uncoated cemented carbide cutting tools in a dry air environment at different environmental chamber pressures. Tests were run in the block-on-ring configuration. The results suggest that the friction coefficient is sensitive to the level of air present, with a noticeable rise in friction coefficient with decreasing pressure or increasing vacuum level. The uncoated cemented carbide sufaces resulted in the highest friction values, whereas the coated grades yielded somewhat lower values even after the coating was removed. The results suggest the importance of friction control in the design of coatings for metal removal processes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.251-252
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• 2006

Tensile and anisotropy test were performed to evaluate the mechanical properties of coated and uncoated steel. These results were used to predict the deference of formability between two sheets. Cup-drawing test was performed to verify formability of two sheets. Also, Cup-drawing test could predict the coefficient of friction and the forming limit. Finite Element Method of cup-drawing was performed to assess the deference between two sheets considering frictional characteristics. This result was compared with the former results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.440-443
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• 2005

Recently the usage of galvanealed steel sheet was increased in order to protect corrosion in automobile industry. So, the alternative of steel sheet was investigated in a point of formability. Generally it was known that uncoated steel sheet has better mechanical properties than coated steel sheet. But, contrary results were sometimes occurred in workplace. This reason is the effect of friction. In this study, the formability of steel sheet considering friction characteristics was investigated with tensile test, cup drawing test and finite element method.

• YAKHAK HOEJI
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• v.33 no.6
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• pp.324-332
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• 1989

Drug release from sulfanilamide granules coated with a polyelectrlyte complex of sodium tripolyphosphate and chitosan was studied. The coating film thickness increased with increasing concentration of chitosan in the coating solution and the drug release rates of the coated granules were significantly reduced comparing with those of the uncoated granules. $T_{50%}$ of the uncoated granules was 6 minutes, but those of the granules coated with chitosan-sodium tripolyphosphate from 0.5, 0.7, and 0.9% (w/v) chitosan-HCl solution were 27, 135, and 180 minutes, respectively in distilled water. In dissolution medium at pH 6.8, $T_{50%}$ of the uncoated granules was 4 minutes, but those of the granules coated with chitosan-sodium tripolyphosphate from 0.5, 0.7, and 0.9(w/v)% chitosan-HCl solution, were 32, 135, and 160 minutes, respectively.

• Journal of Korean Society of Steel Construction
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• v.23 no.1
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• pp.51-59
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• 2011

Although an uncoated CFT column with a high axial-force ratio can be used to secure fire resistance for two hours or less in low-rise buildings, it does not satisfy the three-hour-long fire resistance required in high-rise buildings. Accordingly, so that the uncoated CFT column could be used for high-rise buildings, additional measures for the improvement of its fire resistance should be proposed. In this regard, the use of a Double CFT column as a measure for improving the fire resistance of the uncoated CFT column was proposed in this paper. A fire resistance test was conducted on an uncoated CFT column and a Double CFT column in real scale, under a load. Through such test, the effect of the Double CFT column on fire resistance was evaluated and then compared with that of a variant shape of the cross-section of a steel column.