• Journal of Biosystems Engineering
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• v.39 no.4
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• pp.290-298
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• 2014

Purpose: To ascertain the increase of the farm income that predominantly relies on human resources by mechanizing Welsh onion harvesting, a tractor-mounted Welsh onion harvester was developed in this study. Method: An experiment for evaluating harvesting performance was performed for the developed Welsh onion harvester in an actual Welsh onion farm. The harvest performance was evaluated at the tractor running speeds of 5.0 cm/s, 11.4 cm/s and 15.8 cm/s, by comparing the operating efficiency, harvest rate, and damage rate of the Welsh onion harvester. Results: The performance of the harvester was rated as very good, with a 100% harvest rate, regardless of tractor running speed. Furthermore, it is shown that work efficiency of the harvester is expected to increase as the running speed increases. Nonetheless, the damage rate of the harvested Welsh onions at running speeds 5.0 cm/s, 11.4 cm/s, and 15.8 cm/s, increased correspondingly and proportionally to speeds from 4.55% to 6.53% and to 11.29%. The residual amount of soil on the harvested Welsh onions was about 0.24% of their weight showing excellent soil-removal performance of the harvester. Conclusion: The developed Welsh onion harvester is believed to improve the labor productivity and cultivation environment of Welsh onion farmhouses by the mechanization of the harvesting process that is currently associated with the largest amount of labor hours.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.184-189
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• 2016

Recently, due to limitation of $CO_2$ gas emission and increase of demand to reduce energy consumption, lots of researches are conducted to harvest wasted heat energy with a thermoelectric module to produce electricity by Seebeck effect. This study was conducted to analyze characteristics of the thermoelectric module to apply for a heat energy harvesting device. Thermoelectric module composed of bismuth telluride was tested with various temperature conditions to analyze thermoelectric behavior of the module. Power generation efficiency of the thermoelectric module for various temperature condition was analysed with both experimental and theoretical methods. From the results, an optimum condition to harvest wasted heat energy with the thermoelectric module more efficiently was proposed.

• Composites Research
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• v.34 no.6
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• pp.400-405
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• 2021

In this study, a composite material frame was designed to increase the energy harvesting efficiency of polyvinylidene fluoride (PVDF) ribbon harvesters which are installed inside smart shoes. In order to minimize the amount of deformation in the load direction of the frame, it was designed using carbon continuous fiber composites and its complex shaped structure was manufactured using a 3D printer. In order to calculate the amount of deformation of the insole and midsole of the shoes under the condition of the load generated during walking, the insole and midsole were modeled using the distributed spring elements. Using finite element analysis, the elongation of ribbon-type harvesters mounted on smart shoes was calculated during walking. It is expected that the predicted elongation of the harvester can be utilized to increase the energy harvesting efficiency of smart shoes.

• Science of Emotion and Sensibility
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• v.21 no.3
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• pp.141-150
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• 2018

The purpose of this study is to investigate three-dimensional embroidery techniques for creating conductive fabric materials. Such techniques can increase the efficiency of energy harvesting by increasing the fabric's area during rubbing and brushing. We also investigate the fabric structure of the triboelectric energy harvesting type. Two experiments were conducted for this purpose. In Experiment I, the three-dimensional embroidery technique(satin technique, file technique) and the conductive fabric material(copper-based MPF, nickel-based MPF) were selected as the main variables affecting the efficiency of triboelectric energy harvesting from the human body. Four samples were fabricated according to a combination of two variables. In Experiment II, the harvesters fabricated by the three-dimensional embroidery method showing the highest efficiency were subjected to brushing processes and the voltages generated after processing were analyzed. As a result, in both conductive fabric materials, the pile embroidery fabric structure showed a higher efficiency than the satin structure. These results show the triboelectric energy harvesting principle, which is proportional to the charge density and the generated voltage. It can be seen that the structure of pile embroidery fabric with a large friction area is advantageous for increasing efficiency compared to satin embroidery-fabric structure with a relatively small friction area. Moreover, the energy harvesting efficiency after brushing was higher than that before processing due to the increased friction area, and it was found that the brushing method is advantageous for increasing the triboelectric-energy harvest.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.3
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• pp.261-266
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• 1984

To determine the optimum harvesting methods for high yield and quality, harvesting time were tested from 30 to 45 days after heading with five days intervals, using combine, binder and knap-sack type reaper (KSTR) in harvesting machines. Under the consideration of moisture contents of grain, operating time, grain loss, harvesting cost and quality, the optimum time of barley harvesting for mechanization was 35 to 40 days after heading. Combine and binder were recommended as the suitable machines for barley harvest in the operating efficiency and harvesting cost.

• Smart Media Journal
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• v.8 no.2
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• pp.21-28
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• 2019

Recent research on energy harvesting wireless sensor networks focuses on the development of techniques to solve the limited energy resource problem and to extend the whole network life efficiently. Energy harvesting technology can increase the lifetime of a network, but data transmission becomes unavailable when it harvests energy from radio frequency, resulting longer network delay with respect to the increased time in energy harvesting. Therefore, building energy harvesting wireless sensor network should consider the possible network delay as well as the network lifetime problem. In this paper, we propose a new MAC protocol that minimizes end-to-end network delay by adjusting the data transmission time for a packet based on estimating the energy for data transmission along with the amount of traffic flowing into the network and harvested energy. For this goal, it engineers an energy management mechanism that adjusts the sleep time of the network by measuring energy harvesting time. In addition, with simulation results it shows that the proposed MAC protocol improves the performance in terms of energy consumption and end-to-end delay, compared to the existing MAC protocols.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.1
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• pp.51-56
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• 2012

This paper reports the generation efficiency and the thermal performance of a thermoelectric generator (TEG) harvesting energy from the waste heat of high power electronic components. A thermoelectric (TE) model containing thermal boundary resistances is used to predict generation efficiency and junction temperature of a high power electronic component. The predicted results are verified with measured values, and the discrepancy between prediction and measurement is seen to be moderate. The verified TE model predicts generation efficiencies, junction temperatures of the component, and temperature differences across a TEG at various source heat flows associated with various electrical load resistances. This study explores effects of the load resistance on the generation efficiency, the temperature difference across a TEG, and the junction temperature.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.6
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• pp.2686-2708
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• 2020

This paper investigates the energy efficiency of energy harvesting (EH) bidirectional cooperative sensor networks, in which the considered system model enables the uplink information transmission from the sensor (SN) to access point (AP) and the energy supply for the amplify-and-forward (AF) relay and SN using power-splitting (PS) or time-switching (TS) protocol. Considering the minimum EH activation constraint and quality of service (QoS) requirement, energy efficiency is maximized by jointly optimizing the resource division ratio and transmission power. To cope with the non-convexity of the optimizations, we propose the low complexity iterative algorithm based on fractional programming and alternative search method (FAS). The key idea of the proposed algorithm first transforms the objective function into the parameterized polynomial subtractive form. Then we decompose the optimization into two convex sub-problems, which can be solved by conventional convex programming. Simulation results validate that the proposed schemes have better output performance and the iterative algorithm has a fast convergence rate.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.11
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• pp.890-897
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• 2014

This work investigated the electromechanical performance of a cantilevered vibration energy harvester incorporating the single crystal PMN-PZT, manufactured with the most recent technology of solid-state single crystal growth. The performances of single crystal PMN-PZTs with two different crystallographic axes such as [011] and [001] are compared with those of PZT ceramics. From the investigations, it is shown that the [001]-poled PMN-PZT is advantageous for the excitations containing single dominant frequency component, while the single crystal [011]-$d_{32}$ is superior in terms of the energy storage density and energy conversion efficiency.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.407-410
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• 2009

A piezoelectric device which converts mechanical vibration energy into electrical energy is able to harvest energy and the usable energy is mW ${\sim}$ W, hence a converter is necessary to acquire the energy efficiently. Various limited conditions should be considered for the design of AC/DC converter for energy harvesting of a piezoelectric device supplying small amount of energy. In addition to simple structure, compact size, light weight and high efficiency, the energy harvesting AC!DC converter should adopt the technique of self operating, in which only the harvested energy from the piezoelectric device is available. This paper proposes new AC/DC resonant boost converter to harvest efficiently electrical energy from mechanical vibration energy, analyzes the operating characteristics of the converter and proves its feasibility for energy harvester with PSPICE simulation and experiment.