Seok Joong Kim

Parallel genetic algorithms for the earliness-tardiness job scheduling problem with general penalty weights

Abstract The purpose of this paper is to develop parallel genetic algorithms for a job scheduling problem on a single machine. The objective of the scheduling is to minimize the total generally weighted earliness and tardiness penalties from a common due date. A binary representation scheme is employed for coding job schedules into chromosomes. Parallel subpopulations are constructed by considering only jobs that can be processed first in the schedule. Three important genetic algorithm operators; reproduction, crossover and mutation are implemented by reflecting the problem-specific properties. The efficiency of the parallel genetic algorithm is illustrated with computational results.

Synthesis and characterization of polyaniline–polycarbonate composites prepared by an emulsion polymerization

Abstract Electrically conductive polymer composite, polyaniline (PANI)–dodecylbenzene sulfonic acid (DBSA)/polycarbonate (PC), was prepared by an inverted emulsion polymerization in which DBSA played both roles of surfactant and dopant. Fourier transform infrared (FT-IR) spectroscopy for the composite showed the existence of hydrogen bonding between PANI and PC which caused the increase of glass transition temperature with PANI content. Moreover, the electrical conductivity increased around the glass transition temperature because the PANI chains contacted more frequently and facilitated the electron transfer through the hydrogen bonding between PANI and PC. In addition, it was proved by mechanical property that tensile strength of the composite decreased with PANI content because PANI functioned as a defect in PC matrix and the tensile modulus continuously increased because PANI had a higher rigidity of molecules.

Electrical conductivity change of polyaniline–dodecyl benzene sulfonic acid complex with temperature

Polyaniline–dodecylbenzene sulfonic acid (PAn–DBSA) complex was thermally treated and its conductivity and structure change were investigated. The conductivity increased linearly from 1.1 × 10−4 to 3.0 × 10−1 S/cm on thermal heating until 140°C, but decayed above 200°C. The increase was caused by an additional thermal doping resulting from an increasing mobility of undoped dopants. After the thermal doping, the formation of the layered structure of PAn–DBSA is made. The decrease was caused by the thermal decomposition of dopants. The conductivity changes at a high temperature was strongly dependent on the nature of the dopant. The results were confirmed by means of X-ray patterns and Fourier transform infrared spectra obtained in the heating and cooling processes of polyaniline.

Annealing effect on the electrochemical property of polyaniline complexed with various acids

The annealing effect on the electroactivity of polyaniline (PAn) complexed with various acids has been investigated. The polyaniline—p-toluene sulfonic acid complex (PAn—pTSA) and polyaniline—hydrochloric acid complex (PAn—HCl) show decreased electroactivities with annealing temperature, but the polyaniline—dodecylbenzene sulfonic acid complex (PAn—DBSA) shows an increase in electroactivity up to an annealing process of 150°C, and then a decrease at an annealing process of 180°C. The increase of the electroactivity for PAn—DBSA can be explained by an additional thermal doping of undoped DBSA with annealing. The electrical conductivities at a high temperature of 230°C are in the order of PAn—pTSA > PAn—DBSA > PAn—HCl. PAn—pTSA shows the highest conductivity because pTSA shows the most thermal stability. Decreased conductivity at a high temperature may be due to the dedoping and structural change that cannot be recovered by redoping.

Electrochemical properties of dodecylsulfate-doped polypyrrole films in aqueous solution containing NH4Cl and ZnCl2

Abstract Dodecylsulfate-doped polypyrrole (PPy) films were electrochemically synthesized in aqueous solution containing sodium dodecylsulfate. In order to examine the applicability of the films to electrode materials, the electrochemical properties and charge-discharge properties were investigated in the aqueous solution containing 0.4 M NH 4 Cl and 0.1 M ZnCl 2 . From cyclic voltammetric and chronoamperometric results, it was concluded that the good electrochemical reversibility was due to the fast mobilities of NH 4 + and Cl − instead of the dodecylsulfate trapped in the polymer matrix. The charge-discharge tests of the Zn/(NH 4 Cl, ZnCl 2 )/PPy cell showed an open-circuit voltage of 1.3 V after 80 min, specific capacity of 59 Ah kg −1 and energy density of 77 Wh kg −1 .

A design of multi-layered location registration areas in microcellular systems

Multi‐layered location registration areas are considered to minimize the control signals at boundary cells in the microcellular systems. The decision of multi‐layered location registration (LR) areas is formulated as an integer programming problem by examining the regional subscriber densities, traffic flows and call arrival rates. By relaxing the constraints of forward and reverse control channels the problem is decomposed into a number of subproblems each of which corresponds to a layer. Each subproblem is solved via a modified graph partitioning algorithm. Feasible LR areas are obtained by considering the two relaxed constraints. Computational experiments are performed in a system with 80 microcells to investigate the performance of the proposed multi‐layer scheme. The simulation results indicate that the two‐layer scheme generally outperforms the one‐layer and three‐layer methods in view of control signals.

pH effect on the electrochemical redox reaction of disulfide with polyaniline film electrode in organic solution

Abstract 2,5-Dimercapto-1,3,4-thiadiazole/polyaniline (DMcT/PAn) composite electrode is prepared by DMcT electrochemical oxidation on PAn film electrode in DMcT solution with a different pH. The electroactivity, DMcT concentration profile in the PAn film and the in situ resistivity of the composite are investigated in the electrolyte solution with or without DMcT. The composite film prepared in acidic condition shows higher current density and better electroactivity than those prepared under neutral and basic conditions because the protons may contribute to the protonation of PAn film. When DMcT/PAn composite is transferred into the solution without DMcT, it has enhanced electroactivity such as an anodic peak shift to a lower potential and increased cathodic current. The enhancement of electroactivity is considered to be caused by the increase of ion diffusion coefficient and the decrease of electrical resistivity. The ion diffusivity increases due to the detachment of excess DMcT from the film and the resistivity decreases by the dissociation of DMcT from the imine group of PAn.

Electrochemical properties of dodecylbenzenesulfonic acid doped polyaniline film in various organic electrolyte solutions

Summary form only given. For an electroactive polyaniline the microstructure formation of the film and the role of surfactant in electrochemical redox process were investigated by cyclic voltammetry, ac impedance spectroscopy and x-ray diffraction pattern. Polyaniline doped with surfactant was prepared by emulsion polymerization in the presence of dodecylbenzene sulfonic acid (PAn-DBSA). Electrochemical reversibility, cyclic stability, capacitance, and redox reactivity were studied in various organic electrolyte solutions containing LiClO/sub 4/ and their properties were explained by the mobility of Li/sup +/ cations for charge neutrality in the film. According to the results of X-ray diffraction patterns, the electrochemical redox process changed the microstructure of PAn-DBSA film and the DBSAs were stacked in double layer structure in tile film.