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 & Nanofiber. The organization has 14820 authors who have published 28884 publications receiving 554131 citations.

The Late Permian to Triassic Hongseong-Odesan Collision Belt in South Korea, and Its Tectonic Correlation with China and Japan

Abstract: We propose a new correlation of Middle Triassic (ca. 230 Ma) eclogites from the Hongseong area of the southwest Gyeonggi Massif, South Korea, with the Dabie-Sulu collision belt of China. Late Permian (ca. 257 Ma) mangerites that intrude the Odesan area in the eastern part of the Gyeonggi Massif show geochemical characteristics of collisional tectonic settings, implying that the Hongseong collision belt extends to the Odesan area. In the Higo terrain of southernmost Japan, sapphirine-bearing granulites and related high-temperature metamorphic rocks reveal ca. 245 Ma ultrahigh-temperature (UHT) metamorphic conditions. This metamorphism is well matched with the 245 ± 10 Ma UHT metamorphism estimated for spinel granulite in the Odesan area, suggesting that the Dabie-Sulu collision zone continues through the Hongseong-Odesan belt into the Higo area and that Paleozoic subduction complexes in southwest Japan represent an eastern extension of the Dabie-Sulu collision belt. The Paleozoic subduction complexes in Ja...

Lead-Free Perovskite Nanowire-Employed Piezopolymer for Highly Efficient Flexible Nanocomposite Energy Harvester.

Abstract: In the past two decades, mechanical energy harvesting technologies have been developed in various ways to support or power small-scale electronics. Nevertheless, the strategy for enhancing current and charge performance of flexible piezoelectric energy harvesters using a simple and cost-effective process is still a challenging issue. Herein, a 1D-3D (1-3) fully piezoelectric nanocomposite is developed using perovskite BaTiO3 (BT) nanowire (NW)-employed poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) for a high-performance hybrid nanocomposite generator (hNCG) device. The harvested output of the flexible hNCG reaches up to ≈14 V and ≈4 µA, which is higher than the current levels of even previous piezoceramic film-based flexible energy harvesters. Finite element analysis method simulations study that the outstanding performance of hNCG devices attributes to not only the piezoelectric synergy of well-controlled BT NWs and within P(VDF-TrFE) matrix, but also the effective stress transferability of piezopolymer. As a proof of concept, the flexible hNCG is directly attached to a hand to scavenge energy using a human motion in various biomechanical frequencies for self-powered wearable patch device applications. This research can pave the way for a new approach to high-performance wearable and biocompatible self-sufficient electronics.

The effect of molecular weight and the linear velocity of drum surface on the properties of electrospun poly(ethylene terephthalate) nonwovens

Abstract: In this study, we evaluated the effect of the molecular weight of the polymer on electrospun poly(ethylene terephthalate) (PET) nonwovens, and their mechanical properties as a function of the linear velocity of drum surface. Polymer solutions and electrospun PET nonwovens were characterized by means of viscometer, tensiometer, scanning electron microscope (SEM), wide angle X-ray diffraction measurement (WAXD) and universal testing machine (UTM). By keeping the uniform solution viscosity, regardless of molecular weight differences, electrospun PET nonwovens with similar average diameter could be obtained. In addition, the mechanical properties of the electrospun PET nonwovens were strongly dependent on the linear velocity of drum surface. From the results of the WAXD scan, it was found that the polymer took on a particular molecular orientation when the linear velocity of drum surface was increased. The peaks became more definite and apparent, evolving from an amorphous pattern at 0 m/min to peaks and signifying the presence of crystallinity at 45 m/min.