• Tribology and Lubricants
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• v.27 no.5
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• pp.264-268
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• 2011

In this study, we examined the friction characteristics of a dimple pattern on a carbon nitride coating. The study was conducted with a hexagonal array 40 ${\mu}m$ dimple pattern on a steel bearing containing a CNx coating. The area density of the dimple patterns were varied between 5% and 25%, the speed was varied from 0.06-0.26 m/s, and the load was varied between 20-100N. In general, we found that as the velocity increased, the friction coefficient increased. Furthermore, the friction coefficient was lowest at a load of 40N. The friction coefficient of the non-coated specimen was 0.025-0.15; on the other hand, the friction coefficient of the coated specimen was 0.002-0.02. Thus, we determined that the coated materials could reduce the friction coefficient by a factor of 7.5.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.4
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• pp.321-326
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• 2005

Chemical mechanical polishing(CMP) process is essential technology to be applied to manufacturing the dielectric layer and metal line in semiconductor devices. It has been known that overpolishing in CMP depends on pattern selectivity as a function of density and pitch, and use of fixed abrasive pad(FAP) is one method which can improve the pattern selectivity. Thus, dishing & erosion defects can be reduced. This paper introduces the manufacturing technique of FAP using hydrophilic polymers with swelling characteristic in water and explains the self-conditioning phenomenon. When applied to tungsten blanket wafers, the FAP resulted in appropriate performance in point of uniformity, material selectivity and roughness. Especially, reduced dishing and erosion was observed in CMP of tungsten pattern wafer with the proposed FAP.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.17-20
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• 1998

Thermal behavior of Flow Pattern Defect (FPD) and Large Pit (LP) in Czochralski Silicon crystals was investigated by applying high temperature ($\geq$1100$^{\circ}C$) annealing and non-agitation Secco etching. For evaluation of the effect of LP upon device performance / yield, DRAM and ASIC devices were fabricated. The results indicate that high temperature annealing generates LPs whereas it decreases FPD density drastically, and LP does not have detrimental effects on the performance /

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.715-718
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• 2004

In this paper, we studied the characteristics of new polishing pad, which can apply W-CMP process for global planarization of multi-level interconnection structure. The hardness and density were measured as a function of groove pattern. Also, we compared the pore size through the SEM photograph. Finally, we investigated the CMP characteristics with five different kind of groove pattern sample. Through the above results, we can select optimum groove pattern, so we can expect to begin home product of polishing pad.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.16 no.4
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• pp.383-391
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• 1987

An experimental investigation has been conducted to determine the flow pattern for two-component , two-phase mixtures which flow vertically upwards in concentric annuli based on the measurement for the local void fraction and the distribution of the local void fraction in various radial locations in the annular gap. The annular test section consists of a lucite outer tube whose inside diameter is 38mm and a stainless steel rod, The rod diameter is either :2mm,16mm or 20mm. It is demonstrated that the probability density function of the fluctuations in void fraction may be used as an flow pattern indicator and the local void fraction distribution depends on the flow pattern and radial location in the annular passage.

• The Research Journal of the Costume Culture
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• v.9 no.5
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• pp.759-769
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• 2001

The principal purpose of this study is focused on the fabrics used in Kaya period by investigating the imprinted fabrics on the remains of the old tomb of Dohang-ri and Jeesan-dong which were built around the late 4th century to the late 6th century. Most of the remains are plain weaved, however there is one remain that 4-end complex gauze with patterned, and the other is weaved with geometrical pattern which were plain weave with 2 · 1 twill and 3 · 1 twill. The imprinted fabrics that had twists had S twists only. Of all the fabrics that were examined, the most loose one had the density of 8 × 6/cm, the most fine fabric had the weft density of 91.8 strands/cm and the warp density cannot be counted. It is No. 416 of Doharg-ri tomb that has the highest ratio of density as 3.15. All the fabrics observed by SEM and Polarizing Microscope are hemp.

• Journal of Ocean Engineering and Technology
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• v.18 no.5
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• pp.22-28
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• 2004

This study constructed a 3D real-time numerical model that predicts the water quality and movement characteristics of the inner bay, considering the characteristics of the wind-driven current and density current in estuaries, generated by the river discharge from the Hyeong-san river and oceanic water of the Eastern sea. The numerical model successfully calculated the seawater circulation current of Yeong-il Bay, using the input conditions oj the real-time tidal current, river discharge, and weather conditions during March 2001. This study also observed the wind-driven current and density current in estuaries that are effected by the seawater circulation pattern of the inner bay. We investigated and analyzed each impact factor, and its relationship to the water quality of Yeong-il bay.

• Journal of Astronomy and Space Sciences
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• v.33 no.3
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• pp.207-210
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• 2016

Under the assumption of the presence of a medium-scale E × B drift vortex of plasma in the daytime midlatitude F region, and using a simplified ionospheric model, we demonstrate that the E × B drift produces noticeable perturbations in the horizontal distribution of the plasma density in the upper F region. The pattern of ion density perturbations shows two separate medium scale domains of enhanced and reduced ion density with respect to the background. The E × B drift does not produce multiple small-scale ion density irregularities through plasma mixing because of the suppression effect of the field-aligned ambipolar plasma diffusion.

• Korean Journal of Ecology and Environment
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• v.43 no.4
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• pp.513-517
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• 2010

The diel swarming of Moina macrocopa and the relationship between environmental factors were evaluated in a shallow reservoir. The littoral density of Moina macrocopa maintained low from night to noon, reached maximum density at the afternoon with compact swarms at the waters' edge, and dispersed after sunset. The recruitment of Moina macrocopa and changes of water temperature (r=0.709, p<0.001) and juvenile fish density (r=0.511, p=0.002) in the littoral zone showed a significant positive relationships. After the induction of diel horizontal migration toward littoral zone, therefore, direct juvenile fish predation pressure should be induced Moina macrocopa swarming.

• Journal of Communications and Networks
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• v.11 no.5
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• pp.455-463
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• 2009

We consider the challenges of finding good puncturing patterns for rate-compatible low-density parity-check code (LDPC) codes over additive white Gaussian noise (AWGN) channels. Puncturing is a scheme to obtain a series of higher rate codes from a lower rate mother code. It is widely used in channel coding but it causes performance is lost compared to non-punctured LDPC codes at the same rate. Previous work, considered the role of survived check nodes in puncturing patterns. Limitations, such as single survived check node assumption and simulation-based verification, were examined. This paper analyzes the performance according to the role of multiple survived check nodes and multiple dead check nodes. Based on these analyses, we propose new algorithm to find a good puncturing pattern for LDPC codes over AWGN channels.