Chonbuk National University

About: Chonbuk National University is a education organization based out in Jeonju, South Korea. It is known for research contribution in the topics: Apoptosis & Graphene. The organization has 14820 authors who have published 28884 publications receiving 554131 citations.

Supersymmetry parameter analysis : SPA convention and project

Abstract: High-precision analyses of supersymmetry parameters aim at reconstructing the fundamental supersymmetric theory and its breaking mechanism. A well defined theoretical framework is needed when higher-order corrections are included. We propose such a scheme, Supersymmetry Parameter Analysis SPA, based on a consistent set of conventions and input parameters. A repository for computer programs is provided which connect parameters in different schemes and relate the Lagrangian parameters to physical observables at LHC and high energy e(+)e(-) linear collider experiments, i.e., masses, mixings, decay widths and production cross sections for supersymmetric particles. In addition, programs for calculating high-precision low energy observables, the density of cold dark matter (CDM) in the universe as well as the cross sections for CDM search experiments are included. The SPA scheme still requires extended efforts on both the theoretical and experimental side before data can be evaluated in the future at the level of the desired precision. We take here an initial step of testing the SPA scheme by applying the techniques involved to a specific supersymmetry reference point.

Micro electrochemical milling

Abstract: In this paper, electrochemical machining (ECM) for fabricating micro structures is presented. By applying ultra short pulses, dissolution of a workpiece can be restricted to the region very close to an electrode. Using this method, 3D micro structures were machined on stainless steel. Good surface quality of the structures was obtained in the low concentration electrolyte, 0.1 M H2SO4. In ECM, when the machining depth increases, structures taper. To reduce the taper, a disc-type electrode is introduced. By electrochemical milling, various 3D micro structures including a hemisphere with 60 µm diameter were fabricated.

In situ synthesis of the reduced graphene oxide–polyethyleneimine composite and its gas barrier properties

Abstract: The ternary roles of polyethyleneimine (PEI) as a reducing agent, a surface modifier and a polymer host have been presented to fabricate reduced graphene oxide (RGO) based composite films with improved gas barrier property. The PEI functionalized RGO dispersion is prepared and filtered to fabricate thin films with a brick and mortar structure. The simultaneous reduction and functionalization of graphene oxide (GO) by PEI are confirmed by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy analysis. The good dispersion of graphene sheets in the PEI matrix and the layered structure is confirmed by X-ray diffraction and field emission scanning electron microscopy analyses. Thermogravimetric analysis also confirms the removal of oxygen functionalities from GO and the attachment of PEI chains to the RGO sheets. The electrical conductivity of the RGO film is found to be 492 S m−1 at low content of PEI (PEI : GO = 0.02 : 1), and increasing the PEI content leads to a decrease in the electrical conductivity of the films. In contrast, the water dispersibility and gas barrier properties increase with increasing PEI content in the composite film.

Metal-organic framework derived Co3O4/MoS2 heterostructure for efficient bifunctional electrocatalysts for oxygen evolution reaction and hydrogen evolution reaction

Abstract: Fabrication of highly efficient, sustainable and low-cost nonprecious metal oxide for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is exceedingly challenging and warranted for overall water splitting. Herein, we synthesized cobalt nanoleaves metal-organic framed work (MOF) on nickel foam substrate with uniform growth. After calcination of Co-MOF, molybdenum disulfide nanosheets is grown by a facial hydrothermal method. The as-prepared heterostructure (Co3O4/MoS2) can act as bifunctional electrocatalysts for overall water splitting. Under optimized condition, synthesized Co3O4/MoS2 heterostructure catalyst exhibited excellent catalytic activity for both OER and HER in 1 M KOH solution with a current density of 20 mA cm−2 at overpotential of 230 mV for OER and 205 mV for HER (@ j = 10 mA cm−2) and Tafel slopes of 45 and 98 mV dec-1, respectively. The superior catalytic activity for both OER and HER arises from the unique heterostructure of Co3O4/MoS2 and the synergistic effects of Co3O4 and MoS2.

Unrelated parallel machine scheduling with setup times using simulated annealing

Abstract: This paper presents a scheduling problem for unrelated parallel machines with sequence-dependent setup times, using simulated annealing (SA). The problem accounts for allotting work parts of L jobs into M parallel unrelated machines, where a job refers to a lot composed of N items. Some jobs may have different items while every item within each job has an identical processing time with a common due date. Each machine has its own processing times according to the characteristics of the machine as well as job types. Setup times are machine independent but job sequence dependent. SA, a meta-heuristic, is employed in this study to determine a scheduling policy so as to minimize total tardiness. The suggested SA method utilizes six job or item rearranging techniques to generate neighborhood solutions. The experimental analysis shows that the proposed SA method significantly outperforms a neighborhood search method in terms of total tardiness.