• Korean Journal of Environment and Ecology
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• v.24 no.6
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• pp.638-647
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• 2010

This study was performed in order to analyze influences the actual vegetation between the communities of Pinus densiflora and Quercus mongolica in southern Korea to the species composition of the seed bank in the top soil. The soil samples were collected from the studied plots and transported to the Experimental Glasshouse at Department of Landscape Architecture, Yeungnam University and examined the germinated species individual numbers with species composition and germinated individual numbers by species. The overall germination status was the highest in the herbaceous layers than the layers of tree, sub-tree and shrub, respectively. There were no significantly different between numbers of species and individuals and between actual vegetation and seed bank in the two communities. The woody species marked in the seed bank as a pioneer or edge species than in the two communities which are in the stage of mid or late successional species. Although the plant species in the herbaceous layers was highly influenced to the species composition of the seed bank, but no significantly different was showed within the same forest zone and latitudes of Korean peninsula. As the pioneer or edge species of the actual vegetation possibly will be higher the buried in the top soil layer and this phenomenon will influence overall species composition in the seed bank population.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.350-350
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• 2011

ZnO는 II-VI족 화합물 반도체로서 3.37 ev의 band gap energy와 60 mv의 exciton binding energy를 가지며 차세대 소자로 다양한 분야에서 연구되어지고 있다. ZnO 박막과는 다르게 ZnO nano structure는 효율성과 특성 향상의 이점으로 태양전지와 투명전극 소자에 많은 연구가 되고 있으며 UV 레이저, 가스센서, LED, 압전소자, Field Emitting Transistor (FET) 등 다양한 응용분야에서 연구되고 있다. 본 연구에서는 유리 기판 위에 RF Magnetron sputtering법을 이용해 ZnO buffer layer를 다양한 두께(~1,000${\AA}$)로 증착한 뒤, Zn powder (99.99%)를 지름 2inch 석영관 안에 넣어 Thermal furnace장비를 이용하여 Thermal Evaporation법으로 약 500$^{\circ}C$에서 30분 동안 촉매 없이 성장 하였다. 수직성장된 ZnO 나노 구조체의 특성을 전계방출주사전자현미경(SEM), X-선 회절패턴(XRD), UV-spectra를 이용하여 분석하였다. SEM 분석을 통하여 ZnO buffer layer위에 성장된 ZnO 나노 구조체는 직경이 약 ~50 nm, 길이가 ~2 um까지 성장을 보였으며, XRD 측정결과, ZnO 우선 성장 방향(002)을 확인하였다. 두 가지 측정을 통하여 ZnO buffer layer의 유무에 따라 성장 특성이 향상되었음을 확인하였으며, 이는 buffer layer가 seed 역할을 한 것으로 사료된다. UV-spectra 측정을 통하여 가시광 영역(400~780 nm)에서 60%대의 투과도를 보여 가시광 영역에서 투명성을 요구하는 전자 소자 및 광소자 등에 적용 가능성을 확인하였다. 이 연구를 통하여 우수한 투과도를 가지며 유리 기판위에 수직성장된 ZnO 나노구조체는 태양전지와 플렉서블 디스플레이 등 다양한 활용 분야를 제시할 수 있다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.6
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• pp.442-446
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• 2005

This study was conducted to obtain basic information on the utilization of wheat flour for good organoleptic evaluation score. Wheat seed was milled by Buhler test mill. Volatile flavor compounds of five milling fractions such as Break $I{\cdot}II (B_1+B_2)$, Reduction I ($R_1$), Reduction II ($R_2$), Bran and Short were determined and their differences were discussed. There was significant difference in quantity of flavor compounds but no difference in qualitative composition among milling fractions. The outer layer of wheat endosperm ($R_2$ layer) showed higher amount of m-xylene and n-butanol in volatile flavor com­pounds compared with inner endosperm layer ($B_1,\;B_2,\;R_1$). The $R_2$ layer showed quantitatively higher composition of major flavor compounds than inner endosperm layer ($B_1,\;B_2,\;R_1$). This result points out that the $R_2$ layer exhibited stronger flavor than $B_1,\;B_2$, and Rl layers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.48-48
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• 2009

최근 나노광전소자 응용에 큰 관심을 받는 물질인 산화물 나노선은 앞으로 불어 올 나노소재 시대를 여는 선두 물질이다. 이러한 산화물 나노선 가운데 가장 큰 관심을 받는 물질로는 산화아연 나노선을 들 수 있다. 삼화아연 나노선은 상온에서 큰 엑시톤 결합에너지 및 큰 밴드갭을 가지고 있으며 투명성 및 소자구동시 안정성을 지니고 있어 그 응용이 기대된다. 하지만 이러한 나노선을 이용한 광전소자 응용은 bottom-up 방식을 기초로 한 대면적 소자제작이 어렵다. 이러한 bottom-up 방식의 나노소자 제작에서 필요한 나노선 성장기술은 금속 catalyst 없이 대면적 성장, 나노선 수직어레이, 나노선의 고온성장, 기판 사이에 발생하는 자발적 계면층 제거 등으로 대표된다. 또한 나노선의 결정성 및 광특성 향상을 위해서는 고온성장이 불가피한데, 실리콘 기판과 같이 격자상수 불일치도가 큰 기판에서는 나노선 성장이 이루어지지 않고 다시 탈착되어 구조물이 성장되지 않는다. 본 연구에서는 선택적 삼원계 단결정 씨앗층을 이용하여 길이/직경 비가 매우 향상된 MgZnO 나노와이어를 interfacial layer 없이 수직으로 고온에서 성장하여 산화물 전계방출 에미터로서의 가능성을 확인하였다.

• Electrical & Electronic Materials
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• v.28 no.2
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• pp.25-33
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• 2015

Ruthenium (Ru) thin films were grown on thermally-grown $SiO_2$ substrates by atomic layer deposition (ALD) using a sequential supply of four kinds of novel zero-valent Ru precursors, isopropyl-methylbenzene-cyclohexadiene Ru(0) (IMBCHDRu, $C_{16}H_{22}Ru$), ethylbenzen-cyclohexadiene Ru(0) (EBCHDRu, $C_{14}H_{18}Ru$), ethylbenzen-ethyl-cyclohexadiene Ru(0) (EBECHDRu, $C_{16}H_{22}Ru$), and (ethylbenzene)(1,3-butadiene)Ru(0) (EBBDRu, $C_{12}H_{16}Ru$) and molecular oxygen (O2) as a reactant at substrate temperatures ranging from 140 to $350^{\circ}C$. It was shown that little incubation cycles were observed for ALD-Ru processes using these new novel zero-valent Ru precursors, indicating of the improved nucleation as compared to the use of typical higher-valent Ru precursors such as cyclopentadienyl-based Ru (II) or ${\beta}$-diketonate Ru (III) metallorganic precursors. It was also shown that Ru nuclei were formed after very short cycles (only 3 ALD cycles) and the maximum nuclei densities were almost 2 order of magnitude higher than that obtained using higher-valent Ru precursors. The step coverage of ALD-Ru was excellent, around 100% at on a hole-type contact with an ultra-high aspect ratio (~32) and ultra-small trench with an aspect ratio of ~ 4.5 (top-opening diameter: ~ 25 nm). The developed ALD-Ru film was successfully used as a seed layer for Cu electroplating.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.357.2-357.2
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• 2014

Ruthenium (Ru) 박막은 우수한 화학적 열적 안정성 및 높은 일함수(4.7eV) 특성으로 인해 20 nm급 이하의 차세대 DRAM capacitor의 전극 물질 및 Cu metalization을 위한 seed layer로 각광을 받고 있다. Ru박막의 나노스케일 정보전자소자로의 적용을 위해서는 두께제어가 용이하고 3D 구조에서 우수한 단차 피복 특성을 갖는 atomic layer deposition (ALD)을 이용한 박막 형성이 필수적이다. 이에 본 연구에서는 ALD 방법을 이용하여 0가의(cymene) (1,5-hexadiene) Ru (0) (C16H24Ru) 전구체를 합성, ALD 방법을 이용하여 우수한 초기성장거동을 갖는 Ru 박막을 증착 하였다. 형성된 Ru 박막의 표면 형상, 두께, 밀도를 주사전자현미경(Scanning electron microscopy)과 X-선 반사율 측정(X-ray reflectometer)으로 조사하였다. 또한 전기적 특성을 4침법(four-point-probe)으로 측정하였고, 박막의 화학적 조성과 결정성의 정보를 X-선 광전자분광법(X-ray photoelectron spectroscopy)과 X-선 회절(X-ray diffraction)을 이용하여 확인하였다.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.6
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• pp.36-50
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• 2009

To suggest the native plants combination for restoration of the dissected sloping area, the plant communities of thirty seven quadrats from five localities of mid-southern part of Korean peninsula were surveyed from 2007 to 2008. Their flora, vegetation structure, and dominant species based on the importance value were investigated. And the soil characters (pH, moisture content, water holding capacity, and organic matter) of each dominant species were analyzed. Also, germination tests were performed to check the stability of restored native plants using seed chips. As a result, 79 native plants were suggested for the dissected sloping area : 20 trees and subtrees for the upper layer, 18 shrubs and vines for the middle layer, and 41 herbs for the lower layer, taken together their flora, dominant species, vegetation structure, soil condition, germination test, flowering period.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.6
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• pp.546-549
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• 2007

As a rule, high temperature superconducting coated conductors have multi-layered buffers consisting of seed, diffusion barrier and cap layers. Multi-buffer layer deposition requires longer fabrication time. This is one of main reasons which increases fabrication cost. Thus, single buffer layer deposition seems to be important for practical coated conductor process. In this study, a single layered buffer deposition of $CeO_2$ for low cost coated conductors has been tried using thermal evaporation technique. 100 nm-thick $CeO_2$ layers deposited by thermal evaporation were found to act as a diffusion layer. $1\;{\mu}m-thick$ SmBCO superconducting layers were deposited by thermal co-evaporation on the $CeO_2$ buffered Ni-5%W substrate. Critical current of 90 A/cm was obtained for the SmBCO coated conductors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.240-241
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• 2007

In general, high temperature superconducting coated conductors have intermediary buffers layer consisting of seed, diffusion barrier and cap layers. Simplification of the oxide materials buffer architecture in the fabrication of high temperature superconducting coated conductors is required because the deposition of multi-layers buffer architecture leads to a longer manufacturing time and a higher cost process of coated conductors. Thus, single buffer layer deposition seems to be important for practical coated conductor manufacturing process. In this study, a single gradient layered buffer deposition process of YZO for low cost coated conductors has been tried using DC reactive sputtering technique. About several thick YZO gradient single buffer layers deposited by DC co-sputtering process were found to act as a diffusion layer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1794-1798
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• 2004

We present a fabrication method of high aspect ratio 100nm-scale nickel stamper using e-beam writing for the injection molding of optical grating patterns. Conventional nickel stamper is fabricated by nickel electroplating process which is followed by seed layer deposition. In this paper, we have used chrome coated blank mask without anti-reflection layer of CrON in order to simplified electroplating process. In experimental study, we have optimized electron-beam dosage for 100nm-scale optical grating patterns with 2.5-aspect ratio, and fabricated nickel stamper using above grating patterns as PR mold. Fabricated nickel stamper have showed height of 240$\pm$20nm and width of 116$\pm$6nm.