• 한국재료학회지
• /
• 제22권4호
• /
• pp.202-206
• /
• 2012

$CoSi_2$ was formed through annealing of atomic layer deposition Co thin films. Co ALD was carried out using bis(N,N'-diisopropylacetamidinato) cobalt ($Co(iPr-AMD)_2$) as a precursor and $NH_3$ as a reactant; this reaction produced a highly conformal Co film with low resistivity ($50\;{\mu}{\Omega}cm$). To prevent oxygen contamination, $ex-situ$ sputtered Ti and $in-situ$ ALD Ru were used as capping layers, and the silicide formation prepared by rapid thermal annealing (RTA) was used for comparison. Ru ALD was carried out with (Dimethylcyclopendienyl)(Ethylcyclopentadienyl) Ruthenium ((DMPD)(EtCp)Ru) and $O_2$ as a precursor and reactant, respectively; the resulting material has good conformality of as much as 90% in structure of high aspect ratio. X-ray diffraction showed that $CoSi_2$ was in a poly-crystalline state and formed at over $800^{\circ}C$ of annealing temperature for both cases. To investigate the as-deposited and annealed sample with each capping layer, high resolution scanning transmission electron microscopy (STEM) was employed with electron energy loss spectroscopy (EELS). After annealing, in the case of the Ti capping layer, $CoSi_2$ about 40 nm thick was formed while the $SiO_x$ interlayer, which is the native oxide, became thinner due to oxygen scavenging property of Ti. Although Si diffusion toward the outside occurred in the Ru capping layer case, and the Ru layer was not as good as the sputtered Ti layer, in terms of the lack of scavenging oxygen, the Ru layer prepared by the ALD process, with high conformality, acted as a capping layer, resulting in the prevention of oxidation and the formation of $CoSi_2$.

• 한국토양비료학회지
• /
• 제45권1호
• /
• pp.9-15
• /
• 2012

This study was performed to produce basic data for silty reclaimed tidal lands and to develop techniques of environmentally-friendly utilization in agricultural system. We chose the two sites in Saemangeum reclaimed tidal lands, one (Site I) has been treated with cultivating green manure and conducting the desalinization process through submergence since April, 2007 and the other (Site II) has been under natural condition without artificial treatment. In situ and ex situ physic-chemical properties were determined and comparisons were made for soil profiles examined at these two sites in April 2009. Surface soil of Site I had lower EC and higher field saturated hydraulic conductivity than those of Site II, uncultivated land. Especially, exchangeable sodium content was lowest in Site I Ap1 layer than in other layers. This is probably due to flooding desalination and green manure cultivation. Besides, Ap1 and A2 layers of soil profile in Site I showed brighter soil color and more root observation than those of Site II. This is probably due to green manure cultivation. By the large, for high cash upland crops and intensive agricultural use of silty reclaimed tidal land, site-specific soil ripening such as flooding desalination and green manure cultivation could be useful.

• 한국토양환경학회지
• /
• 제2권1호
• /
• pp.99-107
• /
• 1997

본 연구에서는 일련의 회분식 규모의 실험을 통해 소수성 유기오염물질로 오염된 토양에 토양세척기법을 적용함에 있어서 필요한 최적의 운전조건을 도출하고 세척후 분리된 상등액중에 포함된 유기오염물질 및 세척제를 유기용매를 이용하여 효율적으로 분리.회수하기 위한 방안을 모색하고자 하였다. 사용된 계면활성제는 토양과 결합될 우려가 적은 비이온계 계면활성제중 독성이 거의 없으며 국내에서 대량 생산되어 수급이 원활한 계면활성제를 선별하여 소수성 유기오염물질인 n-dodecane(4,000mg/kg dny Soil)으로 오염된 토양에 대해 세척시간, 계면활성제 용액의 농도, 진탕비, 온도 등에 따른 세척효율의 변화를 조사하였다. 실험결과 계면활성제의 HLB(hydrophile-liphophile balance)값이 MSR(molar solubility ratio) 값과 함께 토양세척시 중요한 변수로 작용하였다. HLB값이 낮아 유탁액을 형성하지 못하는 OA-5나 sophorolipid는 10% 이내의 극히 낮은 세척효율을 보였다. 그러나 안정된 유탁액을 형성하는 HLB값 범위내에서는 소수성 유기오염물질에 대한 액상실험에서의 용해도가 큰 계면활성제가 유리하였다. 높은 HLB값을 갖는 OA-14는 OA-9 보다 안정된 유탁액을 형성하지만 용해도에 대한 지표인 MSR값이 OA-9보다 작아 약 20%정도의 낮은 세척효율을 보였다. 안정된 유탁액을 형성하는 동시에 용해도가 높은 OA-9용액이 단독으로 쓰일 때는 최대 60%정도의 세척효율을 보였다. 또한 OA-9세척유출수로부터 유기용매인 벤젠을 이용하여 anthracene을 회수하고자 하는 경우, 세척유출수의 온도를 $30^{\circ}C$, pH는 2로 조절하는 것이 회수 효율 측면에서 바람직하다.

• Plant Biotechnology Reports
• /
• 제2권3호
• /
• pp.191-198
• /
• 2008

Germplasm characterization and evolutionary process in viable populations are important links between the conservation and utilization of plant genetic resources. Here, an investigation is made, based on molecular and biochemical techniques for assessing and exploiting the genetic variability in germplasm characterization of taro, which would be useful in plant breeding and ex situ conservation of taro plant genetic resources. Geographical differentiation and phylogenetic relationships of Indian taro, Colocasia esculenta (L.) Schott, were analyzed by random amplified polymorphic DNA (RAPD) and isozyme of seven enzyme systems with specific reference to the Muktakeshi accession, which has been to be proved resistant to taro leaf blight caused by P. colocasiae. The significant differentiations in Indian taro cultivars were clearly demonstrated by RAPD and isozyme analysis. RAPD markers showed higher values for genetic differentiation among taro cultivars and lower coefficient of variation than those obtained from isozymes. Genetic differentiation was evident in the taro accessions collected from different regions of India. It appears that when taro cultivation was introduced to a new area, only a small fraction of genetic variability in heterogeneous taro populations was transferred, possibly causing random differentiation among locally adapted taro populations. The selected primers will be useful for future genetic analysis and provide taro breeders with a genetic basis for selection of parents for crop improvement. Polymorphic markers identified in the DNA fingerprinting study will be useful for screening a segregating population, which is being generated in our laboratory aimed at developing a taro genetic linkage map.

• Proceedings of the National Institute of Ecology of the Republic of Korea
• /
• 제3권3호
• /
• pp.129-138
• /
• 2022

Reintroduction programs have been promoted across the world to recover and rehabilitate endangered birds through ex situ captive breeding and releasing to the nature. The ultimate aims of these reintroduction programs are recovery of sustainable populations in natural habitats. To ensure the success of the reintroduction programs, it is necessary to examine the followings in order to increase the success rate of releasing along with the development of captive breeding techniques: 1) Adequate habitat provision, 2) adaptability of captive-bred individuals, 3) survivability of released individuals, and 4) social interest and will. Before releasing captive-bred individuals, it should be reviewed whether there are habitats in which the limiting factor is removed, and assessed their long-term safety. The quantity and quality of the released individuals must be considered to increase the chances for mate selection, maintain genetic diversity, and acquire the ability to adapt to the wild. The release method must be decided in consideration of characteristics of the target habitats and individuals, and rational means such as careful observation, evaluation, and feedback must be provided throughout the release process. For the long-term success of recovery projects, social awareness, sustainable support, and related experts are needed. Satisfying these criteria can help to increase the success rates of reintroduction programs. For the bird reintroduction program in the future, the feasibility of the methods and procedures must be closely reviewed before starting.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제11권6호
• /
• pp.8-17
• /
• 2006

현장비원위치(Ex-situ) 공법 적용이 불가능한 부지에서, 디젤로 오염된 오염 토양과 지하수를 동시에 복원하기 위하여 과산화수소를 이용한 현장원위치 화학적 산화법(chemical oxidation)과 공기분사법(air-sparging)을 연계한 복합 복원 공정의 정화 효율 규명을 위한 실내 실험을 실시하였다. TPH 농도가 2,401 mg/kg(A 토양)과 9,551 mg/kg(B 토양)인 두 종류의 현장 오염 토양을 대상으로 과산화수소용액을 이용한 화학적 산화법의 디젤 제거 효율 규명을 위한 배치(회분식) 실험 결과, 과산화수소 50% 용액에 의해 토양 초기 TPH 농도의 18%와 15%까지 감소하였다. 과산화수소 용액 20%를 이용한 칼럼 세정 실험 결과, 세정에 의해서 A 토양과 B 토양의 경우 각각 초기 TPH 양의 78%와 72%가 제거되었다. 칼럼 실험에서 과산화수소의 산화반응에 의해 완전 분해되어 무기가스상(주로 $CO_2$과 $H_2O$)으로 제거된 양까지 고려한다면, 과산화수소용액이 오염 토양과 접촉하면서 충분한 산화과정을 거쳐 대부분의 유류가 토양으로부터 제거되었음을 알 수 있었다. 공기분사법을 이용한 디젤 오염 지하수 정화 실험의 경우, TPH 농도가 820 mg/L인 고농도의 인공 지하수 경우에도 공기분사 72시간 이내에 폐수배출허용기준인 5 mg/L 보다 낮아져, 디젤 제거 효율이 매우 높은 것으로 나타났다. 다만, 오염 토양 내 다량의 디젤 자유상이 존재하는 경우 토양으로부터 지하수로의 지속적인 자유상 디젤의 질량 이동에 의하여, 공기분사법의 지하수 정화 효율은 매우 낮았다. 마지막으로, 과산화수소를 이용한 현장원위치 화학적 산화법과 공기분사법을 연계한 복합 공정의 디젤 정화 효율을 규명하는 박스 실험을 실시하였다. 토양 내 자유상 디젤을 먼저 제거하기 위해 과산화수소 용액을 이용한 토양세정법을 실시한 후, 토양 내 TPH가 제거 되는 정도에 따라 후차적으로 공기분사법을 적용함으로써 토양 및 지하수로부터 디젤을 효과적으로 제거할 수 있었다. 20% 과산화수소 용액의 23 L 세정과 2,160 L의 공기분사에 의해 토양의 TPH 농도는 9,551 mg/kg에서 390 mg/kg으로 낮아졌으며, 오염 지하수의 TPH 농도도 5 mg/L 이하로 낮출 수 있었다. 본 실험들에서 얻어진 결과를 바탕으로 실제 현장에서 대단위 공정을 운영하는데 필요한 복원 공정의 최적 조건들을 도출해 낼 수 있으리라 판단되며, 유류로 오염된 토양 뿐 아니라 오염 지하수까지 동시에 정화할 수 있는 복합 공정 개발을 위한 중요한 기술 자료로 이용될 수 있을 것으로 판단된다.

• Applied Science and Convergence Technology
• /
• 제23권6호
• /
• pp.309-316
• /
• 2014

A large particle accelerator requires an ultrahigh vacuum (UHV) system of average pressure under $1{\times}10^{-7}$ Pa for mitigating the impact of beam scattering from the residual gas molecules. The surface inside the beam ducts should be controlled with an extremely low thermal outgassing rate under $1{\times}10^{-9}Pa{\cdot}m^3/(s{\cdot}m^2)$ for the sake of the insufficient pumping speed. To fulfil the requirements, the aluminum alloys were adopted as the materials of the beam ducts for large accelerator that thanks to the good features of higher thermal conductivity, non-radioactivity, non-magnetism, precise machining capability, et al. To put the aluminum into the large accelerator vacuum systems, several key technologies have been developed will be introduced. The concepts contain the precise computer numerical control (CNC) machining process for the large aluminum ducts and parts in pure alcohol and in an oil-free environment, surface cleaning with ozonized water, stringent welding process control manually or automatically to form a large sector of aluminum ducts, ex-situ baking process to reach UHV and sealed for transportation and installation, UHV pumping with the sputtering ion pumps and the non-evaporable getters (NEG), et al. The developed UHV technologies have been applied to the 3 GeV Taiwan Photon Source (TPS) and revealed good results as the expectation. The problems of leakage encountered during the assembling were most associated with the vacuum baking which result in the consequent trouble shootings and more times of baking. Then the installation of the well-sealed UHV systems is recommended.

• 한국산학기술학회논문지
• /
• 제17권9호
• /
• pp.641-646
• /
• 2016

화석 연료의 연소 과정에서 발생하는 그을음 입자의 형상은 작은 구형입자들이 군집체를 이루고 있는 프랙탈 형상을 하고 있기에 기존 Rayleigh나 Mie 탄성 광 산란 이론으로 분석하는 것에는 한계가 있다. 본 논문에서는 Rayleigh-Debye Gans(RDG) 산란 이론을 적용하여 프랙탈 차원을 가지는 미세 입자의 형상을 효과적으로 해석할 수 있는 과정을 자세히 묘사하였다. 이소옥탄 확산 화염에서 발생하는 그을음 입자를 열 영동 채취법을 이용하여 채집한 후, 투과전자현미경을 이용하여 그을음 입자의 형상을 관찰하였다. RDG 산란 이론을 적용하여, 그을음 입자의 프랙탈 형상을 조사 하였고, 그을음 개별 입자의 직경, 입자 수밀도 및 부피 분율을 산출하였다. 이러한 결과들은 그을음의 성장 과정에서는 뚜렷한 증감 경향을 보이진 않았으나, 그을음 산화 과정에선 전부 뚜렷하게 감소하는 경향을 보였다. 본 연구에서 RDG 산란 이론을 이용하여 도출한 그을음 군칩체의 프랙탈 차원은 약 1.82로 이는 기존의 유사연구 결과와 동일하며, 화석연료의 종류에 상관없이 생성된 모든 그을음 입자에 동일한 값을 갖는 것으로 사료된다.

• 한국토양비료학회지
• /
• 제48권2호
• /
• pp.105-118
• /
• 2015

This study was carried out to investigate the effects of profile disturbance with different artificial accumulation history on physico-chemical properties of soil under plastic film house. The investigations included soil profile description using soil column cylinder auger F10cm x h110cm, in situ and laboratory measurements of soil properties at five sites each at the cucumber (Site Ic ~ Vc) and grape (Site Ig ~ Vg) plastic film houses with artificial soil accumulation. The sites except sites Ic, IVc, IVg and Vg, belong to ex-paddy area. The types of accumulates around root zone included sandy loam soil for 3 sites, loam soil for 1 site, saprolite for 2 sites, and multi-layer with different accumulates for 3 sites. Especially, Site IIg has mixed plow zone (Ap horizon) with original soil and saprolite, whereas disturbed soil layers of the other sites are composed of only external accumulates. The soil depth disturbed by artificial accumulation ranged from 20 cm, for Site IIg, to whole measured depth of 110 cm, for Site IVc, Vc, and Site IVg. Elapsed time from artificially accumulation to investigation time ranged from 3 months, Site IIc, to more than 20 years, Site Vg, paddy-soil covering over well-drained upland soil during land leveling in 1980s. Disturbed top layer in all sites except Site Vg had no structure, indicating low structural stability. In situ infiltration rate had no correlation with texture or organic matter content, but highest value with highest variability in Site IIIc, the shortest elapsed time since sandy loam soil accumulation. Relatively low infiltration rate was observed in sites accumulated by saprolite with coarse texture, presumably because its low structural stability in the way of weathering process could result in relatively high compaction in agro-machine work or irrigation. In all cucumber sites, there were water-transport limited zone with very low permeable or impermeability within 50 cm under soil surface, but Site IIg, IIIg, and Vg, with relatively weak disturbance or structured soil, were the reverse. We observed the big change in texture and re-increase of organic matter content, available phosphate, and exchangeable cations between disturbed layer and original soil layer. This study, therefore, suggest that the accumulation of coarse material such as saprolite for cultivating cash crop under plastic film house might not improve soil drainage and structural stability, inversely showing weaker disturbance of original soil profile with higher drainage.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.131-131
• /
• 2013

A single-layer graphene has been uniformly grown on a Cu surface at elevated temperatures by thermally processing a poly(methyl methacrylate) (PMMA) film in a rapid thermal annealing (RTA) system under vacuum. The detailed chemistry of the transition from solid-state carbon to graphene on the catalytic Cu surface was investigated by performing in-situ residual gas analysis while PMMA/Cu-foil samples being heated, in conjunction with interrupted growth studies to reconstruct ex-situ the heating process. The data clearly show that the formation of graphene occurs with hydrocarbon molecules vaporized from PMMA, such as methane and/or methyl radicals, as precursors rather than by the direct graphitization of solid-state carbon. We also found that the temperature for vaporizing hydrocarbon molecules from PMMA and the length of time the gaseous hydrocarbon atmosphere is maintained, which are dependent on both the heating temperature profile and the amount of a solid carbon feedstock are the dominant factors to determine the crystalline quality of the resulting graphene film. Under optimal growth conditions, the PMMA-derived graphene was found to have a carrier (hole) mobility as high as ~2,700 cm2V-1s-1 at room temperature, superior to common graphene converted from solid carbon.