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제방 환경 조건에서 베타글루칸-잔탄검 계열 바이오폴리머가 식물 생장 및 경쟁에 미치는 영향
정형순(Hyungsoon Jeong),신혜지(Haeji Shin),장하영(Ha-young Jang),김은석(Eunsuk Kim) 응용생태공학회 2020 Ecology and resilient infrastructure Vol.7 No.3
최근 미생물 유래 베타클루칸과 잔탄검을 주성분으로 하는 바이오폴리머는 제방 사면을 안정화할 뿐 만 아니라, 하천 식생의 생장을 촉진하는 친환경 신소재로 활발히 연구되고 있다. 그러나 다양한 환경요인과 개체간 경쟁관계가 존재하는 제방 환경에서 바이오폴리머가 식물 군집에 주는 영향은 알려져 있지 않다. 따라서 본 연구에서는 바이오폴리머의 실제적인 생태성 평가를 목적으로, 바이오폴리머가 식물 생장 촉진에 미치는 영향을 제방 환경에서 확인하고, 경쟁관계가 식물 군집 형성에 미치는 영향을 고려하여 경쟁조건에 따른 바이오폴리머 효과도 조사하였다. 연구 목적을 위하여 4종의 식물종 (돌피, 수크령, 익모초 그리고 큰금계국)을 대상으로 전라남도 담양군 삼지교 부근의 자연 제방 (20 m x 10 m)에서 종내/종간 경쟁 조건에 따른 바이오폴리머 효과를 실험하였다. 바이오폴리머 처리는 바이오폴리머 분말, 물, 일반 상토를 일정 비율로 혼합한 바이오폴리머 혼합토를 화분에 채우거나 일반상토 화분의 표면에 3 cm 두께로 도포하는 방법이 사용되었다. 경쟁 조건과 관계없이 바이오폴리머 처리로 대상 식물종들의 뿌리 생육이 촉진되었고 잎의 건중량 대비 엽면적이 감소하였다, Ehgks 수크령의 총 생물량과 지상부 건중량이 증가하였다. 대상종들의 총생물량과 지상부 건중량은 경쟁조건에서 대조구에 비해 감소하였지만, 이러한 경쟁 효과는 모든 바이오폴리머 처리군에서 유사하게 나타났다. 따라서 바이오폴리머는 토양과 혼합되었을 때 일부 식물종의 생장을 촉진시키지만, 식물의 경쟁능력에는 영향을 주지 않는 것으로 보인다. A biopolymer based on microorganism-derived β-glucan and xanthan gum is being studied as a new eco-friendly material that stabilizes the riverbank slope, and also promotes vegetation growth. However, it is still inconclusive whether biopolymers have a positive effect on plant performance in the riverbanks which are subjected to various climatic factors and plant competitions. For a practical ecological evaluation of the biopolymers, their effect on plant growth promotion was studied in a natural environment. Considering the relationship between competition and plant community formation, the effects of biopolymers on competition were also investigated. For four plant species (Echinochloa crus-galli, Pennisetum alopecuroides, Leonurus japonicus, and Coreopsis lanceolata), the biopolymer effects under intra/interspecific competition were tested at the riverbank (20 m × 10 m) near Samjigyo Bridge in Damyang-gun, Jeollanam-do. A biopolymer powder was mixed with water and commercial soil following the manufacturer’s recommendations. The soil mixed with the biopolymer was filled in a pot or applied to the surface of the commercial soil with a thickness of 3 cm. Across the competition treatments, the biopolymer treatment promoted root growth of the target plant species and decreased the specific leaf area. The total biomass and shoot dry weight of P. alopecuroides increased in response to the biopolymer treatment. The competition treatment decreased the total biomass and shoot dry weight compared to the case without competition. Notably, such a competitive effect was similar in all the biopolymer treatments. Thus, biopolymers, when mixed with soil, promote the growth of some plant species, but do not appear to affect the competitive ability of plants.
Temperature Dependence of Electron Mobility in Uniaxial Strained nMOSFETs
Wookyung Sun,Hyungsoon Shin 대한전자공학회 2014 Journal of semiconductor technology and science Vol.14 No.2
The temperature dependence of strainenhanced electron mobility in nMOSFETs is investigated by using a self-consistent Schrodinger-Poisson solver. The calculated results suggest that vertical compressive stress is more efficient to maintain the strain-enhanced electron mobility than longitudinal tensile stress in high temperature condition.
A new weight redistribution technique for electron-electron scattering in the MC simulation
Kim, Jongchol,Shin, Hyungsoon,Lee, Chanho,Park, Y.J.,Min, Hong Shick IEEE 2004 IEEE transactions on electron devices Vol.51 No.9
A novel technique for the weight redistribution after the electron-electron scattering between weighted electrons in the weighted ensemble Monte Carlo simulation is proposed. By generating an additional electron after each electron-electron collision the conservation of energy, momentum and charge is guaranteed, which has not been possible in the previously reported methods. The proposed technique has been successfully applied to an ideal gas simulation. Based on the new model, the tail carrier behavior due to the electron-electron scattering in the n<SUP>+</SUP>-doped silicon is studied.
Temperature Dependence of Electron Mobility in Uniaxial Strained nMOSFETs
Sun, Wookyung,Shin, Hyungsoon The Institute of Electronics and Information Engin 2014 Journal of semiconductor technology and science Vol.14 No.2
The temperature dependence of strain-enhanced electron mobility in nMOSFETs is investigated by using a self-consistent Schr$\ddot{o}$dinger-Poisson solver. The calculated results suggest that vertical compressive stress is more efficient to maintain the strain-enhanced electron mobility than longitudinal tensile stress in high temperature condition.
Evanescent-Mode Analysis of Short-Channel Effects in MOSFETs
Jiyeong Lee,Hyungsoon Shin 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.44 No.1
The short channel effects (SCE) of bulk MOSFETs with super-steep retrograded channels (SSR), fully-depleted SOI, and double-gate MOSFETs have been analyzed using device simulations and a scaling-length () analysis. It is found that the minimum channel length should be larger than 5 and that the depletion thickness of the SSR should be around 30 nm in order to be applicable to 70-nm CMOS technology. A high-kappa dielectric shows a limitation in scaling due to the drain- field penetration through the dielectric unless the equivalent SiO2 thickness is very thin. The SSR gives the smallest SCE of the three structures considered.
Analytic Model of Spin-Torque Oscillators (STO) for Circuit-Level Simulation
Ahn, Sora,Lim, Hyein,Shin, Hyungsoon,Lee, Seungjun The Institute of Electronics and Information Engin 2013 Journal of semiconductor technology and science Vol.13 No.1
Spin-torque oscillators (STO) is a new device that can be used as a tunable microwave source in various wireless devices. Spin-transfer torque effect in magnetic multilayered nanostructure can induce precession of magnetization when bias current and external magnetic field are properly applied, and a microwave signal is generated from that precession. We proposed a semi-empirical circuit-level model of an STO in previous work. In this paper, we present a refined STO model which gives more accuracy by considering physical phenomena in the calculation of effective field. Characteristics of the STO are expressed as functions of external magnetic field and bias current in Verilog-A HDL such that they can be simulated with circuit-level simulators such as Hspice. The simulation results are in good agreement with the experimental data.
Sun, Wookyung,Choi, Sujin,Shin, Hyungsoon The Institute of Electronics and Information Engin 2014 Journal of semiconductor technology and science Vol.14 No.5
The substrate doping concentration dependence of strain-enhanced electron mobility in (110)/<110> nMOSFETs is investigated by using a self-consistent Schr$\ddot{o}$dinger-Poisson solver. The electron mobility model includes Coulomb, phonon, and surface roughness scattering. The calculated results show that, in contrast to (100)/<110> case, the longitudinal tensile strain-induced electron mobility enhancement on the (110)/<110> can be increased at high substrate doping concentration.
Read margin analysis of crossbar arrays using the cell-variability-aware simulation method
Sun, Wookyung,Choi, Sujin,Shin, Hyungsoon Elsevier 2018 Solid-state electronics Vol.140 No.-
<P><B>Abstract</B></P> <P>This paper proposes a new concept of read margin analysis of crossbar arrays using cell-variability-aware simulation. The size of the crossbar array should be considered to predict the read margin characteristic of the crossbar array because the read margin depends on the number of word lines and bit lines. However, an excessively high-CPU time is required to simulate large arrays using a commercial circuit simulator. A variability-aware MATLAB simulator that considers independent variability sources is developed to analyze the characteristics of the read margin according to the array size. The developed MATLAB simulator provides an effective method for reducing the simulation time while maintaining the accuracy of the read margin estimation in the crossbar array. The simulation is also highly efficient in analyzing the characteristic of the crossbar memory array considering the statistical variations in the cell characteristics.</P>
Feasibility Study on Spin-Transfer-Torque based Magnetic-Tunnel-Junction Element as a Memory Cell
YeonHee Park,Seungyeon Lee,Hyungsoon Shin,Seungjun Lee 대한전자공학회 2008 ICEIC:International Conference on Electronics, Inf Vol.1 No.1
Commercialization of Magnetic Random Access Memory (MRAM) is getting very promising by recent introduction of Spin Transfer Torque (STT) switching technology. In this paper, characteristics of an STT-based Magnetic-Tunnel-Junction(MTJ) element have been studied to examine the feasibility of its use as a giga-scale memory element. The switching principle of STT-based memory cell is compared with that of a conventional MRAM cell. Constraints on characteristics of STT-based MTJ element are derived based on the analysis of peripheral circuits for read and write operations. The measurement data reported in the literature are analyzed to verify if they meet the derived constraints. The results show some of the data belong to operating criteria whereas the others need a little improvement in terms of Iwrite/Iread ratio and Jwrite.