• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.744-751
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• 1993

A prototype motorised hand-held mango harvester was designed and fabricated at the faculty of Engineering , University of Agriculture Malaysia. The harvester is aimed at reducing the harvesting operation time, improving the working comfort during the operation and increasing the harvesting capacity. The mango harvester consists of gripping and detaching devices, a power transmission shaft with a 12 V battery operated motor and an aluminium pole together with a collecting chute. Preliminary observation on the harvester's performance showed significant and satisfactory results. It was found out that the magno harvester was capable of harvesting on an average six seconds for each fruit detachment. Further study is being conducted to improve the efficiency and capacity of the mango harvester.

• Journal of Drive and Control
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• v.21 no.2
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• pp.23-29
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• 2024

Potatoes are one of the world's four major crops, and domestic consumption is currently increasing in Korea. However, the mechanization rate of potatoes is very low, and especially, harvesting is the most labor-intensive task in potato production. In Korea, potato-collecting work depends on manpower, so it is necessary to develop a gathering-type harvester that can be used for processes from digging to harvesting. Therefore, in this study, a self-propelled-type potato harvester was developed, and its performance was analyzed to mechanize harvesting. The potato harvester was developed to have a crawler-type driving part with a 60 hp diesel engine and consisted of a digging part that digs potatoes from the ground, a vertical transporting part that transfers the dug potatoes to the height of the collection bag, a separating part that separates debris, such as stones and soil, and a collecting part that loads the collection box. A field test of the potato harvester was conducted, and performance was evaluated by the damage, loss, and debris mixing proportions, which were 2.5%, 2.8%, and 2.6%, respectively. The working capacity was 1.2 h/10 a. The economic analysis results showed that the cost of harvesting work could be reduced by 12.7% compared to manual harvesting.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.670-675
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• 2018

There is a growing interest in EH-WSN (energy-harvesting wireless sensor networks) that can solve power problems in wireless sensor networks. In EH-WSN, on-off duty cycling is being studied in order to balance energy harvesting and consumption. However, the urgency of the sensed data and the energy harvesting rate in the environmental monitoring EH-WSN are important factors to determine the network performance. Therefore, it is necessary to control the duty-cycle period according to the importance of the sensed data and the energy harvesting rate in addition to simply maintaining the balance of the power. In this paper, we analyze the problem of on-off duty cycling in EH-WSN for environmental monitoring and propose an adaptive duty-cycle scheduling scheme considering the priority of sensed data and energy harvesting rate, where the priority of sensed data determined by sensed value and changing rate. The performance of scheduling scheme was analyzed by computer simulations.

• Journal of Electrochemical Science and Technology
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• v.1 no.2
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• pp.69-74
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• 2010

Methodologies to improve photovoltaic performance of dye-sensitized solar cell (DSSC) are reviewed. DSSC is usually composed of a dye-adsorbed $TiO_2$ photoanode, a tri-iodide/iodide redox electrolyte and a Pt counter electrode. Among the photovoltaic parameters of short-circuit photocurrent density, open-circuit voltage and fill factor, short-circuit photocurrent density is the collective measure of light harvesting, charge separation and charge collection efficiencies. Internal quantum efficiency is known to reach almost 100%, which indicates that charge separation occurs without loss by recombination. Thus, light harvesting efficiency plays an important role in improvement of photocurrent. In this paper, technologies to improve light harvesting efficiency, including surface area improvement by nano-dispersion, size-dependent light scattering efficiency, bi-functional nano material, panchromatic absorption by selective positioning of three different dyes and transparent conductive oxide (TCO)-less DSSC, are introduced.

• Journal of Drive and Control
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• v.16 no.4
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• pp.74-79
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• 2019

In this study, an edible fresh corn harvest testing machine was designed and manufactured. And harvesting performance was analyzed through the field test. The testing machine is of the tractor attached type. It is connected to the tractor PTO shaft to transfer power to the each part of the harvesting machine. And it harvests fresh corn by one row through the processes of cutting, stem crushing, detaching, and collecting. The performance test was performed at PTO speed (540, 750, 1050 rpm, respectively), working speed (0.1, 0.15, 0.2 m/s, respectively), and cropping cultivation (row spacing·hill spacing 70·25 cm, 70·40 cm, 90·30 cm, respectively). The performance test was repeated three times in the 15 m section. The detachment loss ratio, uncollected crop ratio, damage ratio, and harvest ratio were analyzed. As a result of the performance test, it was analyzed that the PTO speed 540 rpm, running speed of 0.1 m/s, and row spacing·hill spacing 70·40 cm were the optimal condition.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.4
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• pp.243-250
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• 2020

Energy harvesting is a recent technology involving the harvest and utilization of extremely small surrounding energy. Energy harvesting research is conducted in various fields. Triboelectric nanogenerators (TENGs) are energy harvesting technologies that use static electricity generated by physical movement or friction. Although TENGs generate output power in microwatt levels, they experience high internal impedance compared with other energy harvesting generators, thereby making the continuous transfer of electric power to loads difficult. This study proposes a power management system for TENGs that consists of three stages, that is, an AC/DC rectifier, an impedance coupler switch with a capacitor bank, and a DC/DC converter. In addition, the selection method of the AC/DC rectifier and DC/DC converter is proposed to maximize the amount of power transferred from energy harvesting areas. Furthermore, the impedance coupler switch and capacitor bank are discussed in detail. The validity and performance of the proposed three-stage power management system for TENGs are verified using a prototype system.

• 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 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%.

• 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.

• Korean Journal of Agricultural Science
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• v.33 no.2
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• pp.159-166
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• 2006

Threshing loss was increased due to dropping of the threshing efficiency when the 4 row head-feed combine harvested 5 row rice to improve harvesting performance of a combine. Reasonable design criteria were examined to determine the ranges of both of feed rate and the length of threshing drum for the 4 row head-feed combine being used as a 5-row combine. Harvesting performance increased as working width or working speed increased, it resulted in 15% increase when the working width increased from 4 row to 5 row. Harvesting operations of the 4 row combine performed normally in the 4 row rice in threshing loss less than 1%, however, threshing loss increased to 2.25% in the 5 row due to poor threshing efficiency. The length of threshing drum was increased from 710 mm to 810 mm as well as the speed of crop feed chain was increased from 0.61 m/s to 0.75 m/s so as to improve the poor threshing efficiency resulted from the enlarged working width from the 4 row to the 5 row, which would decrease threshing loss less than 1%.