• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.263-263
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• 2007

In the future, self-contained sensors and processing units will need on-board, renewable power supplies to be truly autonomous. One way of supplying such power is through energy harvesting, processes by which ambient forms of energy are converted into electricity. One energy harvesting technique involves converting kinetic energy, in the form of vibrations, into electrical energy through the use of piezoelectric materials. Researchers are currently investigating how piezoelectric materials can be used to harvest power. This study examines the use of auxiliary structures, consisting of a mechanical fixture and a lead zirconate/lead titanate (PZT) piezoelectric element, which can be attached to any boundary conditions vibrating beam of the any boundary conditions. Adjusting various boundary conditions of these structures can maximize the strain induced in the attached PZT element and improve power output.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.925-928
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• 2013

In this paper, we propose a relay-based wireless power transmission scheme in order to solve the problems of an existing wired power transmission for energy harvesting system. The proposed scheme can be transferred electromagnetic induction-based wireless power transmission by placing a 4-way coils in the energy block. We confirm the reliability of the electricity transmission through the relay control algorithm. Consequently, the proposed scheme can extend the transmit receive paths of transmission power.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.6-10
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• 2015

RF energy harvesting technology is a promising technology for generating the electrical power from ambient RF signal to operate low-power consumption devices(eg. sensor) in wireless communication networks. This paper, motivated by this and building upon existing CR(Cognitive Radio) network model, proposes a optimal control policy for RF energy harvesting CR networks model where secondary users that have low power consumption harvest ambient RF energy from transmission by nearby active primary users, while periodically sensing and opportunistically accessing the licensed spectrum to the primary user's network. We consider that primary users and secondary users are distributed as Poisson point processes and contact with their intended receivers at fixed distances. Finally we can derive the optimal frame duration, transmission power and density of secondary user from the proposed model that can maximize the secondary users's throughput under the given several conditions and suggest future directions of research.

• Journal of IKEEE
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• v.21 no.1
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• pp.66-69
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• 2017

In recent year, energy harvesting technologies from the ambient environments such as light, motion, wireless waves, and temperature again a lot of attraction form research community [1-5] due to its efficient solution in order to substitute for conventional power delivery methods, especially in wearable together with on-body applications. The drawbacks of battery-powered characteristic used in commodity applications lead to self-powered, long-lifetime circuit design. Thermoelectric generator, a solid-state sensor, is useful compared to the harvesting devices in order to enable self-sustained low-power applications. TEG based on the Seebeck effect is utilized to transfer thermal energy which is available with a temperature gradient into useful electrical energy. Depending on the temperature difference between two sides, amount of output power will be proportionally delivered. In this work, we illustrated a low-input voltage energy harvesting circuit applied discontinuous conduction mode (DCM) method for getting an adequate amount of energy from thermoelectric generator (TEG) for a specific wearable application. With a small temperature gradient harvested from human skin, the input voltage from the transducer is as low as 60mV, the proposed circuit, fabricated in a $0.6{\mu}m$ CMOS process, is capable of generating a regulated output voltage of 4.2V with an output power reaching to $40{\mu}W$. The proposed circuit is useful for powering energy to battery-less systems, such as wearable application devices.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.533-536
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• 2016

This paper describes a vibrational energy harvesting circuit with MPPT control. A high-performance AC-DC converter of which the efficiency is improved by using body-bias technique and bulk-driven technique is proposed and applied for the vibrational energy harvesting circuit design. MPPT (Maximum Power Point Tracking) control function is implemented using the linear relationship between the open-circuit voltage of a vibrational device and its MPP voltage. The designed MPPT control circuit traces the maximum power point by periodically sampling the open circuit voltage of a vibrational device, makes the reference voltages using sampled voltage and delivers the maximum available power to load. The proposed circuit is designed with a $0.35{\mu}m$ CMOS process, and the chip area is $1.21mm{\times}0.98mm$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.182-187
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• 2009

In this paper, the power management module of wireless sensor node is designed and fabricated utilizing RF energy from reader antenna of commercial RFID system, which is mainly categorized in the energy harvesting. For this, the rectenna and the high efficient boost converter is designed to get the DC power from RF power for the charging the battery. When the RF power from RFID reader antenna is 1.2[W], the DC power of 3.1[mW] at the distance of 1[m] and 1[mW] at 5.5[m] are obtained. Considering the connection to the battery, the boost converter for enhancing the conversion efficiency is designed. The conversion efficiency at the distance of 4[m] is 79.3[%] and the harvested power is 1.36[mW] which is actually used for the charging the battery. This value is available in the wireless sensor networking.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.346-349
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• 2013

This paper describes a triple-input energy harvesting circuit using solar, vibration and thermoelectric energy with MPPT(Maximum Power Point Tracking) control. The designed circuit employs MPPT control to harvest maximum power available from a solar cell, PZT vibration element and thermoelectric generator. The harvested energies are simultaneously combined and stored in a storage capacitor, and then managed and transferred into a sensor node by PMU(Power Management Unit). MPPT controls are implemented using the linear relation between the open-circuit voltage of an energy transducer and its MPP(Maximum Power Point) voltage. The proposed circuit is designed in a CMOS 0.18um technology and its functionality has been verified through extensive simulations. The designed chip occupies $945{\mu}m{\times}995{\mu}m$.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.9
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• pp.4220-4241
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• 2017

For the downlink energy-harvesting small cell network, this paper proposes an interference management algorithm based on distributed coalitional game. The cooperative interference management problem of the energy-harvesting small cells is modeled as a coalitional game with transfer utility. Based on the energy harvesting strategy of the small cells, the time sharing mode of the small cells in the same coalition is determined, and an optimization model is constructed to maximize the total system rate of the energy-harvesting small cells. Using the distributed algorithm for coalition formation proposed in this paper, the stable coalition structure, optimal time sharing strategy and optimal power distribution are found to maximize the total utility of the small cell system. The performance of the proposed algorithm is discussed and analyzed finally, and it is proved that this algorithm can converge to a stable coalition structure with reasonable complexity. The simulations show that the total system rate of the proposed algorithm is superior to that of the non-cooperative algorithm in the case of dense deployment of small cells, and the proposed algorithm can converge quickly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.620-626
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• 2023

Energy harvesting technology, which converts wasted energy sources in everyday life into usable electric energy, is gaining attention as a solution to the challenges of charging and managing batteries for the driving of IoT sensors, which are one of the key technologies in the era of the fourth industrial revolution. Hybrid energy harvesting technology involves integrating two or more energy harvesting technologies to generate electric energy from multiple energy conversion mechanisms. In this study, a hybrid energy harvesting device called TMPPEG (thermo-magneto-piezoelectric-pyroelectric energy generator), which utilizes low-grade waste heat, was developed by incorporating PVDF polymer piezoelectric components and optimizing the system. The variations in piezoelectric output and thermoelectric output were examined based on the spacing of the clamps, and it was found that the device exhibited the highest energy output when the clamp spacing was 2 mm. The voltage and energy output characteristics of the TMPPEG were evaluated, demonstrating its potential as an efficient hybrid energy harvesting component that effectively harnesses low-grade waste heat.

• Journal of Drive and Control
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• v.20 no.4
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• pp.107-114
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• 2023

Garlic is one of the major seasoned vegetables in Korea along with peppers and onions. Although it is a major cash crop, the aging population of farmers and rising labor and production costs are cited as the reasons for the decreasing production. Accordingly, it is necessary to introduce and spread garlic cultivation mechanization technology to reduce the input labor demand. In this study, conducted a field demonstration in Jeollanam-do using garlic harvesting machinery. In addition, it was intended to improve the mechanization rate of garlic harvesting by deriving factors that can apply to garlic harvesting machines in Jeollanam-do and investigating regional adaptability. As a result of the analysis, it was found that the harvesting performance of the garlic harvester and garlic collector in Jeollanam-do met the agricultural machine test standards. In addition, as a result of calculating the input effect of the mechanized work system compared to the conventional garlic harvesting work system, it was found that there was a labor-saving effect of 96.02%.