• Journal of The Geomorphological Association of Korea
• /
• v.24 no.4
• /
• pp.1-12
• /
• 2017

This study tried to reconstruct paleovegetation environments during the late Holocene with pollen analysis from archeological trenches at the right bank of Geumgang in Sejong-si. The lower hills was dominantly covered with pine trees, while alder trees and hygrophytes extended on the floodplain since 2,000yr BP. The pollen composition of Alnus dominance in the floodplain during the times is different from the general charateristics of Korean peninsula. Such a phenomenon is thought to be influenced by the fluvial process on the floodplain in the middle reaches of Geumgang around Sejong-si. Mihocheon and some tributaries join to Geumgang around Sejong-si, and the channel of Geumgang becomes narrow around the boundary between Sejong-si and Gongju-si. This narrow channel could attribute to the formation of extensive floodplain around Sejong-si. Moreover, human impacts such as agriculture appear continuously since 1,800yr BP.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2011.12a
• /
• pp.183-183
• /
• 2011

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.111-112
• /
• 2007

Silicon nitride (SiN) 박막을 플라즈마 응용화학기상법을 이용하여 증착하였다. SiN박막의 전하밀도는 일반화된 회귀 신경망과 유전자 알고리즘을 이용하여 모델링하였다. PECVD 공정은 Box Wilson 실험계획표를 이용하여 수행하였다. $SiH_4$ 유량변화에 따른 온도의 영향은 미미하였다. 그러나, 저 전력에서의 온도증가 (또는 저온에서의 전력의 증가)에 따라 전하밀도는 급격히 상승하였으며, 이는 [N-H]의 증가에 기인하는 것으로 해석되었다. $SiH_4$ 유량의 증가 (또는 고온에서의 전력의 증가)에 따라 전하밀도는 감소하고 있으며, 이는 [Si-H]의 증가에 기인하는 것으로 이해된다.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2015.11a
• /
• pp.135-135
• /
• 2015

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.221-222
• /
• 2008

In Crystalline Si solar cells, Anti-Reflection Coating is contribute to improvement in energy conversion efficiency due to decrease of optical loss and recombination owing to surface passivation. Porous Si is formed electrochemical etching that uses chemical solution and anodization etching. So It gives that advantage in rapid process time and without high cost equipment. In this paper, We compare Porous Si with $SiO_2$/SiNx ARC and analyze that by anti-reflection coating.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2012.11a
• /
• pp.173-173
• /
• 2012

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.206-206
• /
• 2010

본 연구에서는 신경망을 이용하여 SiN 박막의 특성을 예측하는 모델을 개발하였다. 신경망으로는 일반화된 회귀 신경망 (generalized regression neural network-GRNN)을 이용하였고, GRNN 모델의 예측수행은 유전자 알고리즘 (genetic algorithm-GA)을 이용하여 최적화 하였다. 개발된 모델을 이용하여 증착률과 굴절률 및 균일도를 공정변수의 함수로 예측하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.309-309
• /
• 2010

Silicon Nitride(SiN) 박막을 펄스드 플라즈마 응용화학기상법을 이용하여 저 소스전력의 $SiH_4-N_2$ 플라즈마에서 증착하였다. Duty ratio의 변화에 따른 이온에너지와 굴절률의 변화를 고찰하였다. 저이온에너지는 증착률과 강한 상관성을 보였다. 이온에너지 변수의 증착률에의 영향은 신경망 모델을 이용하여 고찰하였다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.211.1-211.1
• /
• 2014

Recently, the scaling of conventional planar NAND flash devices is facing its limits by decreasing numbers of electron stored in the floating gate and increasing difficulties in patterning. Three-dimensional vertical NAND devices have been proposed to overcome these issues. Atomic layer deposition (ALD) is the most promising method to deposit charge trap layer of vertical NAND devices, SiN, with excellent quality due to not only its self-limiting growth characteristics but also low process temperature. ALD of silicon nitride were studied using NH3 and silicon chloride precursors, such as SiCl4[1], SiH2Cl2[2], Si2Cl6[3], and Si3Cl8. However, the reaction mechanism of ALD silicon nitride process was rarely reported. In the present study, we used density functional theory (DFT) method to calculate the reaction of silicon chloride precursors with a silicon nitride surface. DFT is a quantum mechanical modeling method to investigate the electronic structure of many-body systems, in particular atoms, molecules, and the condensed phases. The bond dissociation energy of each precursor was calculated and compared with each other. The different reactivities of silicon chlorides precursors were discussed using the calculated results.

• Korean Journal of Metals and Materials
• /
• v.47 no.10
• /
• pp.660-666
• /
• 2009

The consolidation of mechanical alloyed $Ti_5Si_3$ powder by electro-discharge-sintering has been investigated. A single pulse of 2.5 to 8.0 kJ/0.34 g was applied to each powder mixture using 300 and $450{\mu}F$ capacitors. A bulk-like solid with $Ti_5Si_3$ phase has been successfully fabricated by the discharge with an input energy of more than 2.5 kJ in less than $160{\mu}sec$. Micro-Vickers hardness was found to be higher than 1350, which is significantly higher than that of a conventional high temperature sintered sample. The formation of $Ti_5Si_3$ and consolidation occurred through a fast solid state diffusion reaction.