Chun-Ho Kim

Evaluation of feeder monitoring parameters for incipient fault detection using Laplace trend statistic

This paper focuses on a systematic and cumulative statistical approach for identifying symptom parameters of incipient faults in distribution feeders. The proposed method aims at providing a tool for evaluating and identifying the best and highly correlated parameters to the faults so that they could be used for incipient fault detection and feeder condition monitoring. The Laplace test statistic is adopted for trend analysis of the event log of candidate parameters and applied to actual feeder event data for online detection and monitoring purposes.

Beneficial effect of aligned nanofiber scaffolds with electrical conductivity for the directional guide of cells

Abstract Conducting polymer-based scaffolds receive biological and electrical signals from the extracellular matrix (ECM) or peripheral cells, thereby promoting cell growth and differentiation. Chitin, a natural polymer, is widely used as a scaffold because it is biocompatible, biodegradable, and nontoxic. In this study, we used an electrospinning technique to fabricate conductive scaffolds from aligned chitin/polyaniline (Chi/PANi) nanofibers for the directional guidance of cells. Pure chitin and random and aligned Chi/PANi nanofiber scaffolds were characterized using field emission scanning electron microscope (FE-SEM) and by assessing wettability, mechanical properties, and electrical conductivity. The diameters of aligned Chi/PANi nanofibers were confirmed to be smaller than those of pure chitin and random nanofibers owing to electrostatic forces and stretching produced by rotational forces of the drum collector. The electrical conductivity of aligned Chi/PANi nanofiber scaffolds was ~91% higher than that of random nanofibers. We also studied the viability of human dermal fibroblasts (HDFs) cultured on Chi/PANi nanofiber scaffolds in vitro using a CCK-8 assay, and found that cell viability on the aligned Chi/PANi nanofiber scaffolds was ~2.1-fold higher than that on random Chi/PANi nanofiber scaffolds after 7 days of culture. Moreover, cells on aligned nanofiber scaffolds spread in the direction of the aligned nanofibers (bipolar), whereas cells on the random nanofibers showed no spreading (6 h of culture) or multipolar patterns (7 days of culture). These results suggest that aligned Chi/PANi nanofiber scaffolds with conductivity exert effects that could improve survival and proliferation of cells with directionality.

Substance-P and transforming growth factor-β in chitosan microparticle-pluronic hydrogel accelerates regenerative wound repair of skin injury by local ionizing radiation

Clinical irradiation therapy for cancer could increase the risk of localized wound complications. This study was conducted to evaluate the potential use of a chitosan microparticle‐pluronic F127 (CSMP‐PF) hydrogel complex containing bioactive molecules, substance P and transforming growth factor‐β1, to regeneratively repair skin damaged by local ionizing radiation (IR). The BALB/c/bkl mice were locally irradiated to their limbs with a single 40 Gy dose of Co‐60 γ rays to induce a skin injury. The morphological characteristics of the chitosan microparticles were analysed by scanning electron microscopy. The amounts of bioactive molecules taken up and released by the CSMP‐PF hydrogel complex were measured. Haematoxylin and eosin staining of IR‐damaged skin showed acanthosis and hyperkeratosis in the epidermis; and damage to hair follicles/skin appendages and adipose tissue, as well as panniculus carnosus, in the dermis. Injection of the CSMP‐PF hydrogel complex into IR‐damaged skin resulted in skin repair, suggesting that the complex has potential for use in the regenerative repair of IR‐damaged skin.