• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.1093-1100
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• 2018

Fast progress in miniaturization and reducing power consumption of semiconductors for wearable devices makes it possible to develop extremely small wearable systems for various application services. This results recent wearable applications to be powered from extremely low-power energy harvesters based on solar, piezo, and TENG sources. In most cases, the harvesters generate power in non-linear manner. Therefore, we implemented and experimented the device platforms to utilize natural frequency of around 3Hz. We also designed two-stage power storages and high efficiency conversion platform to consider such non-linear power harvesting sources. The experiment showed power generation of about 4.67mW/min from these non-linear sources with provision of stable energy storages.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.1
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• pp.319-333
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• 2022

In order to enhance system energy efficiency, bidirectional link resource allocation strategy in GFDM-based multiuser SWIPT systems is proposed. In the downlink channel, each SWIPT user applies power splitting (PS) receiver structure in information decoding (ID) and non-linear energy harvesting (EH). In the uplink channel, information transmission power is originated from the harvested energy. An optimization problem is constructed to maximize weighted sum ID achievable rates in the downlink and uplink channels via bidirectional link power allocation as well as subcarriers and subsymbols scheduling. To solve this non-convex optimization problem, Lagrange duality method, sub-gradient-based method and greedy algorithm are adopted respectively. Simulation results show that the proposed strategy is superior to the fixed subcarrier scheme regardless of the weighting coefficients. It is superior to the heuristic algorithm in larger weighting coefficients scenario.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.1
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• pp.225-234
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• 2019

By using the Triboelectric nanogenerators, known as TENG, we can take advantages of high conversion efficiency and continuous power output even with small vibrating energy sources. Nonlinear energy extraction techniques for Triboelectric vibration energy harvesting usually requires synchronized active electronic switches in most electronic interface circuits. This study presents a nonlinear energy harvesting with high energy conversion efficiency to harvest and save energies from human active motions. Moreover, the proposed design can harvest and store energy from sway motions around different directions on a horizontal plane efficiently. Finally, we conducted a comparative analysis of a multi-mode energy storage board developed by a silicon-based piezoelectricity and a transparent TENG cell. As a result, the experiment showed power generation of about 49.2mW/count from theses multi-fully harvesting source with provision of stable energy storages.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.5
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• pp.559-565
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• 2010

In this study we propose noise energy harvesting for green infrastructure development. In this regard, infrastructures such as railroad, subway, and road are taken into consideration as sources of noise which provides energy through certain wave forms. As the need of recycling noise energy became reasonable due to the increase of infrastructure usage, the capacity and property of our noise energy generating device, which uses electromagnetic induction for electricity generation, are analysed in this paper. Consequently, the outcomes of this experiment show the fact that maximum electricity is generated from the device at a specific point of noise frequency, and the relation between air pressure caused by noise and the electricity generated by the device is in a specific proportional form either linear or non-linear. The major points of developing noise energy generating device in order to apply it into social infrastructure are discussed in this paper as well.

• Journal of Magnetics
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• v.16 no.2
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• pp.150-156
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• 2011

Magnetoelectric (ME) transducers were originally intended for magnetic field sensors but have recently been used in vibration energy harvesting. In this paper, a new broadband vibration energy harvester has been designed and fabricated to be efficiently applicable over a range of source frequencies, which consists of two cantilever beams, two magnetoelectric (ME) transducers and a magnetic circuit. The effects of the structure parameters, such as the non-linear magnetic forces of the ME transducers and the magnetic field distribution of the magnetic circuit, are analyzed for achieving the optimal vibration energy harvesting performances. A prototype is fabricated and tested, and the experimental results on the performances show that the harvester has bandwidths of 5.6 Hz, and a maximum power of 0.25 mW under an acceleration of 0.2 g (with g = $9.8\;ms^2$).

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.6
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• pp.619-624
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• 2015

Owing to miniaturization and low-power electronics, mobile, implanted, and wearable devices have become the main trends of electronics during the past decade. There has been much research regarding energy harvesting to achieve battery-free or self-powered devices. The optimal design problems of a double-pendulum kinetic-energy harvester from human motion are studied in this paper. For the given form factor, the weight of the harvester, and the known human excitation, the optimal design problem is solved using a dynamic non-linear double-pendulum model and an electric generator. The average electrical power was selected as the performance index for the given time period. A double-pendulum harvester was proven to be more efficient than a single-pendulum harvester when the appropriate parameters were used.

• Smart Structures and Systems
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• v.16 no.4
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• pp.579-591
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• 2015

This paper investigates a magnetoelectric (ME) vibration energy harvester that can scavenge energy in arbitrary directions in a plane as well as wide working bandwidth. In this harvester, a circular cross-section cantilever rod is adopted to extract the external vibration energy due to the capability of it's free end oscillating in arbitrary in-plane directions. And permanent magnets are fixed to the free end of the cantilever rod, causing it to experience a non-linear force as it moves with respect to stationary ME transducers and magnets. The magnetically coupled cantilever rod exhibits a nonlinear and two-mode motion, and responds to vibration over a much broader frequency range than a standard cantilever. The effects of the magnetic field distribution and the magnetic force on the harvester's voltage response are investigated with the aim to obtain the optimal vibration energy harvesting performances. A prototype harvester was fabricated and experimentally tested, and the experimental results verified that the harvester can extract energy from arbitrary in-plane directions, and had maximum bandwidth of 5.5 Hz, and output power of 0.13 mW at an acceleration of 0.6 g (with $g=9.8ms^{-2}$).