• Smart Structures and Systems
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• 제19권6호
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• pp.615-624
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• 2017

This paper experimentally investigates the feasibility of harvesting vibration energy from whistles using piezoelectric materials. The end goal of this research is to generate sufficient power from the whistle to power a small radio transmitter to relay a basic signal - for example, a distress call. First, the paper discusses the current literature in energy harvesting from acoustic resonance. Next, the concept of an active whistle is presented. Next, results from energy harvesting experiments conducted on conventional and ultrasonic whistles undergoing human-actuation and actuation by a pressure-regulated air supply are presented. The maximum power density of the conventional whistle actuated by a human at 100 dB sound pressure level is $98.1{\mu}W/cm^3$.

• 제어로봇시스템학회논문지
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• 제15권12호
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• pp.1184-1191
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• 2009

Energy harvesting from environment can make the energy constrained systems such as sensor networks to sustain their lifetimes. However, environmental energy is highly variable with time, location, and other factors. Unlike the existing solutions, we solved this problem by allowing the sensor nodes with mobilizer to move in search of energy and recharge from remote energy station. In this paper we present and analyze a new harvesting aware framework for mobile sensor networks with remote energy station. The framework consists of energy model, motion control system and data transfer protocol. Among them, the objective of our data transfer protocol is to route a data packet geographically towards the target region and at the same time balance the residual energy and the link connectivity on nodes with energy harvesting. Our results along with simulation can be used for further studies and provide certain guideline for realistic development of such systems.

• 전기학회논문지P
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• 제67권3호
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• pp.137-142
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• 2018

Energy harvesting technology is drawing attention as a means of collecting various eco-friendly energy and accumulating residual energy. Recently, differential power processing (DPP) is being developed as part of energy harvesting. This is being studied as a solution to the loss of power generation between power modules and the problems caused by module small losses depending on the size of power production. In this paper, we propose the necessity of the DPP by comparing and analyzing energy harvesting related module integration system and power supply efficiency of DPP. The power efficiency of the converter and the power difference between the wind power and the photovoltaic power supply have been changed to demonstrate the effectiveness of the proposed system.

• Journal of Biosystems Engineering
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• 제25권6호
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• pp.511-516
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• 2000

The strength of the connecting joint of boxthorn(Lycium chinense Mill) fruits to tree twigs was determined experimentally at several pulling angles(0$^{\circ}$, 15$^{\circ}$, 30$^{\circ}$,45$^{\circ}$and 60$^{\circ}$) and at different harvesting seasons from August to November 1999 using an universal testing machine. The detachment force of mature fruits of boxthorn decreased as the pulling angle increased and varied with the harvesting season. The detachment force however did not gradually decreased as the harvesting season advanced due to difference of maturity of fruits from one harvesting season to another. Among three varieties of boxthron Cheongyang gugija Cheongyang native and Cheongyang ＃2, the maximum detachment force was 1.24 N at the pulling angle of zero degree. The highest detachment forve(1.29 N) of mature fruits of boxthorn appeared at the harvesting season of August, 1999.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.925-926
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• 2014

The purpose of this study is intended to improve the efficiency of energy harvesting through the optimal design of the PZT system and the electrical system. To improve the efficiency of energy harvesting, it is necessary to increase the output voltage generated from the PZT. In this study, first the mounting position and shape of the PZT which is attached to the cantilever were optimized. Second electric circuit was optimized by using a series connection of a circuit and the electrical resonance frequency. As a result, we improve the output voltage about 5V.

• 한국물환경학회지
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• 제31권3호
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• pp.328-333
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• 2015

In this study, Mg-Sericite was used as a flocculant to harvest freshwater microalgae, Chlorella. vulgaris. Mg-Sericite separated successfully >95% of the C. vulgaris at the following optimal parameters: Mg/Si mol ratio 1.25 to 1.50, mixing time of 20 min and settling time of 20 min. The harvesting efficiency was pH dependent. The highest harvesting efficiency ($99{\pm}0.3%$) was obtained at Mg/Si mol ratio 1.5 and pH 9 to 11. These results indicated that a biopolymer, Mg-Sericite, can be a promising flocculant due to its high efficiency, low dose requirements, short mixing and settling times. This harvesting method is helpful to lower the production cost of algae for biodiesel.

• Journal of Biosystems Engineering
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• 제24권1호
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• pp.1-8
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• 1999

In this study, the physical properties of live garlic at the harvesting season were measured and analyzed as a fundamental study for developing a garlic harvester. A universal testing machine and a machine vision system were used to obtain mechanical and morphological properties of live garlic, respectively. The moisture content of live garlic at the harvesting season was 50% higher than that of dried garlic. The root of live garlic elongated greatly with respect to the applied tensile force. The relationship between the projected area and the weight of a bulb of live garlic was linear. Such a feature would be applied to develop an effective garlic harvester or garlic quality grader. Other useful physical properties of live garlic at the harvesting season were represented in the study.

• 한국통신학회논문지
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• 제42권1호
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• pp.149-152
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• 2017

본 논문에서는 에너지 하베스팅 (Energy Harvesting) 기술을 적용한 BLE (Bluetooth Low Energy) 비콘에서 전력 관리를 위한 PMIC (Power Management IC)의 출력 전압을 일정하게 유지하기 위한 방안을 연구하였다. 에너지 하베스팅 장치에서 제공되는 에너지를 확보하고 저장하기 위한 축전 장치로 캐패시터를 사용하였고, 주어진 Advertising Interval에서 BLE 모듈에 일정한 전압을 제공하기 위한 최적의 캐패시턴스를 분석하였다.

• ETRI Journal
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• 제39권6호
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• pp.803-812
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• 2017

A decode-and-forward system with an energy-harvesting relay is analyzed for the case when an arbitrary number of independent interference signals affect the communication at both the relay and the destination nodes. The scenario in which the relay harvests energy from both the source and interference signals using a time switching scheme is analyzed. The analysis is performed for the interference-limited Nakagami-m fading environment, assuming a realistic nonlinearity for the electronic devices. The closed-form outage probability expression for the system with a nonlinear energy harvester is derived. An asymptotic expression valid for the case of a simpler linear harvesting model is also provided. The derived analytical results are corroborated by an independent simulation model. The impacts of the saturation threshold power, the energy-harvesting ratio, and the number and power of the interference signals on the system performance are analyzed.

• Journal of Electrochemical Science and Technology
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• 제1권2호
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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.