• 전기학회논문지P
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• 제65권2호
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• pp.84-87
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• 2016

This paper deals with Energy Harvesting using a part of physical energy which is generated by pulldown actions. From a point of energy harvesting view, though it is difficult to regenerate constant energy during pulldown exercise unlike cyclic exercise and running machine exercise, it is possible to regenerate some energies to charge batteries for mobile phones. To investigate possibility of energy harvesting during pulldown exercise, a voltage regulation experiment was performed with a converter circuit and a motor which is attached to the exercise equipment. And we conclude that energy harvesting is possible although its small quantity during pulldown exercises.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.354-362
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• 2000

In Korea, researches on year-round leaf vegetables production system are in progress, most of them focused on environmental control. Therefore, automation technologies for harvesting, transporting, and grading are in great demand. A robot system for harvesting lettuces, composed of a 3-DOF (degree of freedom) manipulator, an end-effector, a lettuce feeding conveyor, an air blower, a machine vision system, six photoelectric sensors, and a fuzzy logic controller, was developed. A fuzzy logic control was applied to determine appropriate grip force on lettuce. Leaf area index and height were used as input variables and voltage as an output variable for the fuzzy logic controller. Success rate of the lettuce harvesting was 94.12%, and average harvesting time was approximately 5 seconds per lettuce.

• Journal of Biosystems Engineering
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• 제25권1호
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• pp.63-70
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• 2000

In Korea, researches for year-round leaf vegetables production system are in progress and the most of them are focused on environment control. Automation technologies for harvesting , transporting and grading need to be developed. This study was conducted to develop harvesting process automation system profitable to a competitive price. 1. Manipulator and end-effector are to be designed and fabricated , and fuzzy logic controller for controlling these are to be composed. 2. The entire system constructed is to be evaluated through a performance test. A robot system for harvesting a lettuce was developed. It was composed of a manipulator with 20DOF (degrees of freedom) an end-effector, a lettuce feeding conveyor , an air blower , a machine vision device, 6 photoelectric sensors and a fuzzy logic controller. A fuzzy logic control was applied to determined appropriate grip force on lettuce. Leaf area index and height index were used as input parameters, and voltage was used as output parameter for the fuzzy logic controller . Success rate of the lettuce harvesting system was 93.06% , and average harvesting time was about 5 seconds per lettuce.

• International Journal of Aerospace System Engineering
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• 제2권1호
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• pp.47-52
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• 2015

The transient phenomenon of self-powered energy-harvesting is assessed using a bond-graph method. The bond-graph is an energy-based approach to describing physical-dynamic systems. It shows power flow graphically, which helps us understand the behavior of complicated systems in simple terms. Because energy-harvesting involves conversion of power in mechanical form to the electrical one, the bond-graph is a good tool to analyze this power flow. Although the bond-graph method can be used to calculate the dynamics of combining mechanical and electrical systems simultaneously, it has not been used for harvesting analysis. We demonstrate the usability and versatility of bond-graph for not only steady analysis but also transient analysis of harvesting.

• 센서학회지
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• 제19권4호
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• pp.313-319
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• 2010

Vibration energy harvesting is an attractive technique for potential powering of low power devices such as wireless sensors and portable electronic applications. Most energy generator developed to date are single vibration frequency based, and while some efforts have been made to broaden the frequency range of energy harvester. In this work, The effect of energy harvesting were investigated at various vibration frequencies, vibration beams, vibration point and test masses. The maximum output voltage of the bimorph piezoelectric cantilever was shifted according to vibration point. Vibration frequency with maximum output voltage decreased with the increasing length of vibration beam and increasing test mass. The sample with vibration beam length 0.5 L generated a peak output voltage of 32 $V_{rms}$ and shows a 45 % increase in voltage output in comparison to the corresponding original bimorph. It was found that a piezoelectric bimorph has a possibility to be as the energy harvesting cantilever, which is successfully tuned over a vibration frequency range to enable a maximum harvesting energy.

• Macromolecular Research
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• 제15권3호
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• pp.272-279
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• 2007

• 대한의생명과학회지
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• 제26권4호
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• pp.376-382
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• 2020

This study was the change of compound and bioactivity were analyzed by different harvesting time (May, August, and November) of Suaeda japonica Makino. The total polyphenol and flavonoid contents of S. japonica were the highest at about 22.81 mg GAE/g and 4.56 mg QE/g, respectively, in the S. japonica harvested in Nov. Also, the contents of quercetin, showed the highest content in Nov harvested S. japonica. In addition, the antioxidative activity of each extract from S. japonica changed depending on harvesting time. For S. japonica harvested in Nov showed the highest DPPH and ABTS radical scavenging activity. From the NO inhibition assay, the S. japonica harvested in Nov had shown the highest anti-inflammatory effects. Therefore, consideration of the optimal harvesting time for S. japonica could be an important factor attributing to its natural antioxidant and anti-inflammatory properties and the optimal harvesting time was confirmed especially to be in Nov.

• 한국전자통신학회논문지
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• 제13권1호
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• pp.153-162
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• 2018

웨어러블 디바이스의 서비스 제공을 위한 지속 가능한 전원에 대한 요구가 높아짐에 따라 에너지 하베스팅의 중요성이 증대되고 있다. 본 연구는 마찰소자를 고려한 다중 에너지 하베스팅 플랫폼인 EH-P를 개발하였다. 높은 전압과 낮은 전류를 가진 하베스팅 소자에 전압을 낮추면서 전류를 높일 수 있는 스위치 회로 제시하였다. PV와 TENG의 상호보완적 구성을 통해 실내 환경에서 짧은 시간동안 MCU가 동작할 수 있는 전압과 전류를 제공할 수 있었다. 결과적으로 제안된 플랫폼을 통해 웨어러블 플랫폼을 동작시키고, 제작된 웨어러블 디바이스에서 전체 소모 전력 요구량의 29%를 제공함으로써 웨어러블 디바이스 사용시간(device life time)을 증가시킬 수 있었다. 이 논문에 제시된 결과는 멀티플 하베스터 플랫폼에서 웨어러블 하베스팅 애플리케이션의 활용을 위한 발전 소자의 가능성을 보여주었다.

• Journal of Semiconductor Engineering
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• 제1권1호
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• pp.13-30
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• 2020

Radio frequency (RF) energy harvesting technology have become a reliable and promising alternative to extend the lifetime of power-constrained wireless networks by eliminating the need for batteries. This emerging technology enables the low-power wireless devices to be self-sustaining and eco-friendly by scavenging RF energy from ambient environment or dedicated energy sources. These attributes make RF energy harvesting technology feasible and attractive to an extended range of applications. However, despite being the most reliable energy harvesting technology, there are several challenges (especially power conversion efficiency, output DC voltage and sensitivity) poised for the implementation of RF energy harvesting systems. In this article, a detailed literature on RF energy harvesting technology has been surveyed to provide guidance for RF energy harvesters design. Since signal strength of the received RF power is limited and weak, high efficiency state-of-the-art RF energy harvesters are required to design for providing sufficient DC supply voltage to wireless networks. Therefore, various designs and their trade-offs with comprehensive analysis for RF energy harvesters have been discussed. This paper can serve as a good reference for the researchers to catch new research topics in the field of RF energy harvesting.

• Journal of Biosystems Engineering
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• 제43권4호
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• pp.311-319
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• 2018

Purpose: The aim of this study is to develop a small combine for harvesting miscellaneous cereal crops. Methods: A prototype small combine was designed and constructed. Its specifications and basic performance were investigated. Results: The prototype small combine for harvesting miscellaneous cereal crops was designed and constructed to reflect similar specifications as those of the conventional combine. The prototype small combine comprises a diesel engine with the rated power/speed of 22.0 kW/2,600 rpm, three-stage primary and two-stage speed range transmission shifts, and a double acting threshing part. The maximum travel speeds of the prototype combine are approximately 0.72 m/s, 2.50 m/s, 0.30 m/s at the low, high speed range shifts in the forward direction, and while traversing in the reverse direction, respectively. The minimum radius of turning was approximately 1.50 m. In a static lateral overturning test, the prototype combine overturned neither to the right nor to left on a $30^{\circ}$ slope. The results of an oilseed rape harvesting test included the maximum operating speed of 0.32 m/s, the grain loss ratio of approximately 9.0%, and the effective field capacity of approximately 10.3 a/h. Additionally, among the outputs in grain outlet, the whole grains, damage grains, and materials other than grain (MOG) ratios accounted for 97.4%, 0.0%, and 2.6%, respectively. Conclusions: The prototype small combine for harvesting miscellaneous cereal crops indicates good driving ability and stability. The results of the oilseed rape harvesting test reveal that the harvesting performance must be enhanced such that the separating and cleaning parts are more suitable for each type of crop, thus reducing grain loss and foreign substances among the outputs in grain outlet. An improved small prototype combine could be used effectively to mechanize the harvesting of miscellaneous cereal crops in small family farms or semi-mountainous areas.