• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.255-255
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• 2010

Recently, nonvolatile memories (NVM) of various types have been researched to improve the electrical performance such as program/erase voltages, speed and retention times. Also, the charge trap memory is a strong candidate to realize the ultra dense 20-nm scale NVM. Furthermore, the high charge efficiency and the thermal stability of SiC nanocrystals NVM with single $SiO_2$ tunnel barrier have been reported. [1-2] In this study, the SiC charge trap NVM was fabricated and electrical properties were characterized. The 100-nm thick Poly-Si layer was deposited to confined source/drain region by using low-pressure chemical vapor deposition (LP-CVD). After etching and lithography process for fabricate the gate region, the $Si_3N_4/SiO_2/Si_3N_4$ (NON) and $SiO_2/Si_3N_4/SiO_2$ (ONO) barrier engineered tunnel layer were deposited by using LP-CVD. The equivalent oxide thickness of NON and ONO tunnel layer are 5.2 nm and 5.6 nm, respectively. By using ultra-high vacuum magnetron sputtering with base pressure 3x10-10 Torr, the 2-nm SiC and 20-nm $SiO_2$ were successively deposited on ONO and NON tunnel layers. Finally, after deposited 200-nm thick Al layer, the source, drain and gate areas were defined by using reactive-ion etching and photolithography. The lengths of squire gate are $2\;{\mu}m$, $5\;{\mu}m$ and $10\;{\mu}m$. The electrical properties of devices were measured by using a HP 4156A precision semiconductor parameter analyzer, E4980A LCR capacitor meter and an Agilent 81104A pulse pattern generator system. The electrical characteristics such as the memory effect, program/erase speeds, operation voltages, and retention time of SiC charge trap memory device with barrier engineered tunnel layer will be discussed.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.45-51
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• 2010

We measured the temperature of target surface inducing by various physical phenomenon on magnetron sputtering target and confirmed the possibilities if the temperature distribution could affect plasma and deposited thin film. The target of magnetron sputtering has two types: round type and rectangular type. In a rectangular target, the concentrated discharge area by corner effect by magnetic field and non-uniform erosion of target are generated. And we found the generation of non-uniform temperature distribution on the target surface from this. This area was $10{\sim}20^{\circ}C$ higher than non-sputtering area. And if particles are generated during sputtering process, they were $20^{\circ}C$ higher than the area where is higher than non-sputtering area. These effects result in non-uniformity of thin films, crack of ceramic target, and shortening target life by non-uniform erosion.

• Food Science and Preservation
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• v.20 no.3
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• pp.317-322
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• 2013

This study was conducted to investigate the effects of pretreatment and different packaging methods on the physicochemical properties of cold vacuum-dried peaches. All the dried peach samples were stored such as $N_2$ gas substitution, vacuum and passive packaged with polyethylene (PE) film and oriented polypropylene (OPP)/aluminum (Al)/PE film at $40^{\circ}C$ for 50 days. The weight change, pH, soluble solids content, titratable acidity, soluble solid-acid ratio (SS/TA), delta E, browning degree and phenolic compounds were analyzed. The weight change and pH were lower in the 0.1% vitamin C-treated group and were significantly lowest in the vacuum-treated OPP/AL/PE. The soluble solids content and the SS/TA were higher in the non-treated groups than in the vitamin C-treated groups. According to the packaging methods, the $L^*$ values were higher in the vacuum, $N_2$ gas and passive package, in that order. In addition, the browning degree and the delta E value were lower in the pretreated groups and significantly lowest in the vacuum-treated OPP/AL/PE with 0.1% vitamin C group. The phenolic compounds were high for the pretreated groups, according to the packaging methods (vacuum > $N_2$ gas> passive), and the OPP/AL/PE was significantly higher than the PE. These results suggest that different packaging materials and pretreatment methods affected the quality of the dried peaches, and the vacuum-OPP/AL/PE film packaging group showed a high quality.

• Geotechnical Engineering
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• v.9 no.1
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• pp.45-58
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• 1993

Paper drain method is one of the methods used for the improvement of soft clay as hydraulic fill sites or the seaside industrial complex. This method adopts a card board as the drain materials instead of sand piles in sand drain method. In this paper 3 types of drain board are used to fond out the characteristics of consolidation by vacuum consolidation model test. So does the no drain board test. This test causes the reduction of pore water pressure to promote the settlement without change of ground water level. Conclusively, the vacuum consolidation shows 3-dimensional behaviors and pore water pressure reaches a negative value in a short time. In addition, it is expected to have a comparatively good consolidation effect using non -woven board, and vacuum loading results in increasing the shear strength at the bottom and top of call layers.

• Resources Recycling
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• v.27 no.1
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• pp.92-105
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• 2018

The present study was carried out to find a suitable drying method for measuring non-evaporable water contents of various hydraulic inorganic materials. In Part 1 of the paper, the case Ordinary Portland cement is discussed. Various drying methods including vacuum and oven drying, and an ignition, were used for the OPC paste and mortar having different w/c. The sole vacuum drying under room temperature led a fluctuation on measurement of hydration degree, while the sole oven drying also yielded unwanted hydration promotion at the early age. A combination of the vacuum and oven drying was considered as a suitable drying method for the OPC case.

• Journal of the Korean Vacuum Society
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• v.7 no.1
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• pp.1-4
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• 1998

We have developed an extreme high vacuum (XHV) system using a new combination pump cpmposed of a suitably shaped NEG(Non-Evaporable Getters) in the body of a sputter-ion pump (SIP). The stainless-steel test chamber was used which had been well oxidized at $450^{\circ}C$ and already yielded XHV with a turbomolecular pumping system. The pressure was measured by a Leybold extractor gauge (EXG,limit:1~$2{\times}10^{-12}$torr, but in the ultimate pressure regionthe EXG shows an unusual sign as $-0.{\times}10^{-12}$ torr which indicates much lower pressure range than its available lower limit. These results are mainly due to the high pumping speed of NEG for hydrogen. Furthermore, use of the SIP combined with the NEG as a XHV pumping system implies the potential for actualization of the surface analysis under XHV environment, and allows one to have a chance tp meet a new world in nanometer science and technology.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.283-283
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• 2012

Sn/In은 금속 특징상 semimetal로 구분되어 지며 증착 두께가 적을수록 Island 구조를 가지며 높은 저항을 가져 비전도 특성을 가지는 금속으로 알려져 있다. 이런 특성이 산업적으로 IT기기의 Decoration에 적용되어 Sn/In을 증착하여 비전도(NCVM: Non Conductive Vacuum Metallization) 증착 Inmold Film으로 활용되고 있다. 비전도 특성은 IT기기의 안테나 성능에 영향을 주기 때문에 Sn/In 박막의 두께에 따른 전기적 특성을 관찰하였다. 또한 Sn/In의 증착 두께에 따라 Inmold Film의 증착감 및 색상 차이가 발생하는 것을 색차계를 통하여 확인할 수 있었다. Sn/In 증착은 Source를 이용하여 Electron beam 방법으로 PET/증착프라이머 Film 위에 Sn/In 박막을 증착 하였으며 증착 조건에 따라 Sn/In 박막특성에 미치는 영향을 연구하였다. 그리고 SEM측정을 통하여 증착조건에 따른 박막의 Morphology도 확인하였다.

• Transactions of Materials Processing
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• v.22 no.3
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• pp.171-177
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• 2013

Vacuum-assisted thermoforming is one of the critical steps for successful application of film insert molding (FIM) to make parts of complex shape. If the thickness distribution of the formed film is non-uniform, then cracking, deformation, warpage, and wrinkling can easily occur at the injection molding stage. In this study, the simulation of thermoforming was performed to predict the film thickness distribution, and the results were compared with experiments. Uniaxial tensile tests with a constant crosshead speed for various high temperatures were conducted to investigate the stress-strain behavior. An instance of yielding occurred at the film temperature of $90^{\circ}C$, and the film stiffness increased with increasing crosshead speed. Two types of viscoelastic models, G'Sell model, K-BKZ model, were used to describe the measured stress-strain relationship. The predicted film thickness distributions were in good agreement with the experimental results.

• Journal of Technologic Dentistry
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• v.32 no.4
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• pp.337-340
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• 2010

Purpose: This study was performed to compare sintering conditions for fabrication of porous Ti implant. Methods: The porous Ti implant samples were fabricated by sintering of spherical Ti powders in vacuum and atmosphere conditions. Surface morphology, composition and phase were analyzed by FE-SEM, EDX and XRD. Results: Sintered Ti implant in the vacuum consisted of particles connected in three dimensions by clear necking without excessive oxide layers. However, sintered Ti implant in atmosphere was formed excessive oxide layers with non-stoichiometric compounds. Conclusion: The porous Ti implant can be sintered in vacuum condition preferably.

• Journal of Power System Engineering
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• v.17 no.1
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• pp.36-41
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• 2013

A study of the possible axisymmetric modes that propagate at low frequencies in buried, water-filled pipes is presented. It is well known that for a vacuum-pipe-vacuum system the sole non-torsional axisymmetric mode that exists at low frequencies is the fundamental L(0,1) mode. When a pipe is filled with water and still surrounded by a vacuum it is also known that another mode then appears which at low frequencies is characterized by predominantly axial water-borne displacements. In addition to these modes. this paper explores two other, less well known axisymmetric modes whose exitence depends on the acoustic properties of the outer medium that surrounds a pipe. The predicted characteristics of these modes are presented and the likelihood of them propagating over any significant distance in a buried water pipe is discussed.