• Title/Summary/Keyword: Electrification

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Relationship between declining oil use and electrification (탈석유화와 전기화의 관계 분석)

  • Choi, Hyo-Yeon;Kim, Sun-Young;Yoo, Seung-Hoon
    • Journal of Energy Engineering
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    • v.23 no.2
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    • pp.119-124
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    • 2014
  • After the oil crisis in 1970s, many countries have tried to reduce oil dependency. Especially, in Korea, rapid declining oil consumption has speedily brought to electrification and a surge in electricity demand. This paper attempts to estimate the relationship between declining oil use and electrification in Korea using OECD panel data covering from 1985 to 2011. To this end, random effect model and fixed effect model are employed. The increase in the ratio of energy oil to total energy consumption by 10%p leads to reduce the electricity demand by about 15%. This result can be useful information to cope with the recent crisis of electric power. In addition, industrial sector is ranked in forth the ratio of industrial electricity use to total electricity use according to the result of comparative analysis of electricity consumption by use in OECD countries. Therefore, industrial sector should be treated as the main target of demand-side management policies for electricity.

Evaluation of h-BN Nanoflakes/Polyimide Composites for a Triboelectric Nanogenerator (육방정질화붕소 나노플레이크/폴리이미드 복합체를 이용한 마찰전기 나노발전기 평가)

  • Park, Sunyoung;Byun, Doyoung;Cho, Dae-Hyun
    • Tribology and Lubricants
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    • v.37 no.4
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    • pp.125-128
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    • 2021
  • A means of enhancing the performance of triboelectric nanogenerators (TENGs) is increasing the differences in work functions between contacting materials. Hexagonal boron nitride (h-BN) exhibits excellent mechanical properties and high chemical stability as well as a high work function. As a result, engineers in the field of energy harvesting have envisioned using h-BN in the electrification layer in TENGs. For the industrial application of h-BN in TENGs, large-scale production is necessary, and h-BN is generally exfoliated and dispersed in various solvents. In this study, we evaluate the performance of a TENG with h-BN nanoflakes in the polyimide (PI) layer. To synthesize a PI composite containing h-BN nanoflakes, h-BN powders are exfoliated and dispersed in poly(amic acid) (PAA), which is the precursor of PI. Then, h-BN dispersion is spin-coated onto the PI film and cured for 2 h under 300℃. This composite material can then be used for the electrification layer in TENGs. Below the electrification layer, an aluminum foil is placed and used as an electrode. When the contact and separation processes with polyethylene terephthalate are repeated, the fabricated TENG shows a maximum power density of 190.8 W/m2. This study shows that h-BN is a promising material for enhancing the performance of the electrification layer in TENGs.

Charge Distribution of Submicron Particles Charged by Spray Electrification or Corona Discharge (분무 및 코로나 방전에 의해 대전된 서브마이크론 입자의 대전량 분포)

  • Lee, Jae-Bok;Bae, Gwi-Nam;Hwang, Jeong-Ho;Lee, Gyu-Won
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.1
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    • pp.124-132
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    • 2001
  • This paper reports on the charge distribution measurements of submicron particles for three different charging mechanisms, which are spray electrification, bipolar ionization and corona discharge process, respectively. The number of elementary charges per particle was investigated by classifying and counting of a discrete mobility class. Charge distribution measurements were performed with NaCl particles generated from a collision atomizer for 0.01, 0.1, 1% NaCl solutions. Experimental results show than charge level of atomized NaCl particles is high and decreases with increasing the dissolved ion concentration. The charge level of the atomized NaCl particles can be reduced to that o Boltzmann equilibrium conditions by the bipolar ionization(Po(sup)210 bipolar ionizer). The charge level on NaCl particles passing through the corona discharge reactor is much higher than those of atomized or bipolar ionized NaCl particles. The evaluation of these measurements results in charge distribution of the submicron particles.

Real-time condition assessment of railway tunnel deformation using an FBG-based monitoring system

  • Zhou, Lu;Zhang, Chao;Ni, Yi-Qing;Wang, Chung-Yue
    • Smart Structures and Systems
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    • v.21 no.5
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    • pp.537-548
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    • 2018
  • A tunnel deformation monitoring system is developed with the use of fiber Bragg grating (FBG) sensing technique, aiming at providing continuous monitoring of railway tunnel deformation in the long term, and early warning for the rail service maintainers and authorities to avoid catastrophic consequences when significant deformation occurs. Specifically, a set of FBG bending gauges with the ability of angle measurement and temperature compensation is designed and manufactured for the purpose of online monitoring of tunnel deformation. An overall profile of lateral tunnel displacement along the longitudinal direction can be obtained by implementing an array of the FBG bending gauges interconnected by rigid rods, in conjunction with a proper algorithm. The devised system is verified in laboratory experiments with a test setup enabling to imitate various patterns of tunnel deformation before the implementation of this system in an in-service high-speed railway (HSR) tunnel.

A Techno-Economic Feasibility Analysis on LVDC Distribution System for Rural Electrification in South Korea

  • Afamefuna, David;Chung, Il-Yop;Hur, Don;Kim, Ju-Yong;Cho, Jintae
    • Journal of Electrical Engineering and Technology
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    • v.9 no.5
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    • pp.1501-1510
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    • 2014
  • Low voltage direct current (LVDC) distribution system is a suitable techno-economic candidate which can create an innovative solution for distribution network development with respect to rural electrification. This research focuses on the use of LVDC distribution system to replace some of KEPCO's existing traditional medium voltage alternating current (MVAC) distribution network for rural electrification in South Korea. Considering the technical and economic risks and benefits involved in such project, a comparative techno-economic analysis on the LVDC and the MVAC distribution networks is conducted using economic assessment method such as the net present value (NPV) on a discounted cash flow (DCF) basis as well as the sensitivity analysis technique. Each would play a role in an economic performance indicator and a measure of uncertainty and risk involved in the project. In this work, a simulation model and a computational tool are concurrently developed and employed to aid the techno-economic analysis, evaluation, and estimation of the various systems efficiency and/or performance.