Economic feasibility of growing herbaceous biomass energy crops in Iowa

Depletion of natural energy resources and environmental degradation caused by current energy resources (fossil fuels) have rekindled interest in energy availability and developing environmentally benign and renewable alternative energy resources. In addition, the reduced productive capacity of soil and environmental problems in rural areas caused by the loss of topsoil has created interest in ways to conserve soil;These concerns have generated considerable attention on the production of herbaceous energy crops on marginal land as a possible solution to meeting future energy demands, addressing environmental concerns, and reducing soil erosion;This research suggests that herbaceous energy crops, especially switchgrass, can be grown productively with minimal erosion, and produced at costs only somewhat higher than fossil fuels. They also have good soil conservation properties on the marginal land in Iowa

Condensation of preformed charge density waves in kagome metals

Charge density wave (CDW) is a spontaneous spatial modulation of electric charges in solids whose general microscopic descriptions are yet to be completed. Layered kagome metals of $A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs) provide a unique chance to realize its emergence intertwined with dimensional effects as well as their special lattice. Here, based on a state-of-the-art molecular dynamics simulation, we uncover that the phase transition to charge ordered states in kagome metals is a condensation process of incoherently preformed CDWs. We demonstrate that charge modulation first preforms on each kagome layer at a well defined temperature but its phase fluctuation proliferates across the entire layers with a $10^5$ times slower frequency than typical phonon vibrations until reaching its freezing temperature. We find that the fluctuation is not random but confined to a limited number of states as a consequence of unavoidable degeneracy in stacking layered charge orders. As the size of interfacial alkali atom increases, the fluctuating phases are shown to counterbalance the condensation of orderings, resulting in a maximized transition temperature for RbV$_3$Sb$_5$. Our results resolve several controversial observations on their CDW formations and highlight a crucial role of interlayer interactions for the charge ordering in kagome metals

Proto-type installation of a double-station system for the optical-video-detection and orbital characterisation of a meteor/fireball in South Korea

We give a detailed description of the installation and operation of a double-station meteor detection system which formed part of a research & education project between Korea Astronomy Space Science Institute and Daejeon Science Highschool. A total of six light-sensitive CCD cameras were installed with three cameras at SOAO and three cameras at BOAO observatory. A double-station observation of a meteor event enables the determination of the three-dimensional orbit in space. This project was initiated in response to the Jinju fireball event in March 2014. The cameras were installed in October/November 2014. The two stations are identical in hardware as well as software. Each station employes sensitive Watec-902H2 cameras in combination with relatively fast f/1.2 lenses. Various fields of views were used for measuring differences in detection rates of meteor events. We employed the SonotaCo UFO software suite for meteor detection and their subsequent analysis. The system setup as well as installation/operation experience is described and first results are presented. We also give a brief overview of historic as well as recent meteor (fall) detections in South Korea. For more information please consult http://meteor.kasi.re.kr .Comment: Technical/instrumentation description of a professional meteor detection system, 23 pages, 20 figures (color/monochrome), 5 tables, submitted to the Journal of Korean Astronomical Society (JKAS, http://jkas.kas.org/, http://jkas.kas.org/history.html

Time Delay Effect on the Love Dynamical Model

We investigate the effect of time delay on the dynamical model of love. The local stability analysis proves that the time delay on the return function can cause a Hopf bifurcation and a cyclic love dynamics. The condition for the occurrence of the Hopf bifurcation is also clarified. Through a numerical bifurcation analysis, we confirm the theoretical predictions on the Hopf bifurcation and obtain a universal bifurcation structure consisting of a supercritical Hopf bifurcation and a cascade of period-doubling bifurcations, i.e., a period doubling route to chaos.Comment: To appear in Journal of Korean Physical Societ

Nano-mechanical behavior of ultra-stable amorphous metallic thin films

Metallic glass has amorphous structure that behave mechanically like solids but show catastrophic failure due to shear band propagation induced by short range order structure, and they are generally produced by quenching. Recently, it is observed that the slower cooling rate provides the larger time available for atoms to rearrange structure before freezing in glassy state, leading to glass transition temperature and thermal stability. These glasses with enhanced thermal stability synthesized by controlled cooling rate make it useful in various field such as mechanical or oxidation protection material. However, mechanical behavior for metallic glass with extraordinary thermodynamic and kinetic stability has not been studied. In this research, we developed a ultrastable metallic glass thin film by physical vapor deposition process at ambient temperature. Thermal stability is investigated using acceleration testing. Mechanical properties are measured using in-situ tensile testing and discuss thermal stability and fracture behavior dependent on compositio

Interpolation for molecular dynamics simulations: from ions in gas phase to proteins in solution

The interpolation technique has shown many promises for simulating chemical dynamics with quantum chemical accuracy at molecular mechanics speed. This is achieved by constructing analytic potential energy surfaces with quantum chemical information at multiple conformational points, without assuming any functional form for the potentials. Here, we briefly review the course the method was developed over the past few decades, with a special focus on the activities in Korea. We also describe its strengths and weaknesses toward describing condensed phase chemical dynamics with the present implementations. Perspectives for future developments toward increasing applicability are discussed as concluding remarks. (c) 2015 Wiley Periodicals, Inc.1122Ysciescopu