• Journal of Biosystems Engineering
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• 제14권1호
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• pp.16-23
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• 1989

An oscillating potato digger for power tillers was designed and constructed to evaluate the effects of vibration on potato digging. Changing the levels of amplitude, frequency, and travel speed, 16 combinations of such parameters were tested in the potato field. The measured variables were harvesting loss and damage, and storing loss of the mechanically harvested potatoes. It was observed that the operation of the digger blade was good with amplitude of 12 mm, frequency of 9.67 Hz, and travel speed of 0.87 km/hr. Under these conditions the harvesting loss and damage were 3.18 % and 0.67 % that are very lower than those of 6.83 % and 9.83 % of traditional harvesting method. The operating efficiency of the experimental digger under optimum operating conditions was about 552 $m^2$ per hour which was about 20 times higher than 27.2 $m^2$ per man per hour of traditional harvest.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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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.

• Smart Structures and Systems
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• 제10권3호
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• pp.299-312
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• 2012

The authors' research efforts recently led to the development of a customized wireless control unit which receives the real-time feedbacks from the sensors, and elaborates the consequent control signal to drive the actuator(s). The controller is wireless in performing the data transmission task, i.e., it receives the signals from the sensors without the need of installing any analogue cable connection between them, but it is powered by wire. The actuator also needs to be powered by wire. In this framework, the design of a power management unit is of interest only for the wireless sensor stations, and it should be adaptable to different kind of sensor requirements in terms of voltage and power consumption. In the present paper, the power management efficiency is optimized by taking into consideration three different kinds of accelerometers, a load cell, and a non-contact laser displacement sensor. The required voltages are assumed to be provided by a power harvesting solution where the energy is stored into a capacitor.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.425-428
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• 2017

본 논문에서는 진동 에너지를 이용하여 에너지를 수확하는 전파 정류 하베스팅 회로를 설계하였다. 설계된 회로는 저전압에서도 전력효율이 우수하도록 Beta-Multiplier를 이용하여 Body-Bias technique을 Negative Voltage Converter에 적용하였으며, Comparator를 Bulk-Driven type으로 설계하였다. 제안된 회로는 $0.35{\mu}m$ CMOS 공정으로 설계하였으며, 설계된 회로의 칩 면적은 $931{\mu}m{\times}785{\mu}m$이다.

• 한국정보통신학회논문지
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• 제24권8호
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• pp.1113-1116
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• 2020

In the EH-WSN(Energy Harvesting Wireless Sensor Network), the routing protocol must consider the power condition of nodes such as residual power and energy harvesting rate. Many EH-WSN studies have emphasized the power aspect and make the urgency of sensed data less important. However, in applications such as environmental monitoring, stability and latency become more important issues than power efficiency for urgent data. In this paper, we designed a routing protocol that can set path according to data urgency. To this end, relay nodes are determined considering the urgency of date. Nodes with poor power do not participate in routing when normal data is generated, so that urgent data can be transmitted reliably with low latency. The performance of the proposed routing protocol is analyzed by computer simulation.

• 유기물자원화
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• 제13권2호
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• pp.98-106
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• 2005

지렁이 사육상으로부터 지렁이를 분리, 수확할 수 있는 지렁이 유인장치를 개발하기 위해서 사육상에서의 지렁이 개체군 동태, 유인물질 및 유인틀내 철망의 mesh 크기, 덮개재질 등에 따른 지렁이 유인효율을 조사하였다. 지렁이 사육상에서 줄지렁이의 최고밀도는 약 $5kg/m^2$이었으며 최고밀도 도달한 이후에는 $4.4{\sim}5.0kg/m^2$의 밀도를 유지하였다. 유인틀내 철망의 mesh 크기는 7mm정도가 적정하였으며 유인틀 덮개는 표면은 매끄럽고 수분을 잘 머금을 수 있는 재질이 적당하였다. 유인틀내에 유인제를 사용하는 경우가 사용하지 않는 경우보다 유인효과가 현저히 높았으며, 유인틀내 유인제량이 많을수록, 유인틀 설치 기간이 길어질수록 지렁이 유인량이 많아졌다. 유인제로서는 분쇄된 배껍질이 제지슬러지보다 우수하였는데 이는 유인제내 당도의 차이에 기인하는 것으로 판단된다. 그러나 현장에서 사용할 수 있을 만큼 충분한 량의 배껍질을 공급하기가 어려우므로 그 대용으로서 설탕물(10%)을 유인물질로 이용하는 방안이 제시될 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술회의 초록집
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• pp.7-7
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• 2010

Energy harvesting from the environment has been of great interest as a standalone power source of wireless sensor nodes for Ubiquitous Sensor Networks(USN). In particular, the piezoelectric energy harvesting from ambient vibration sources has intensively researched because it has a relatively high power density comparing with other energy scavenging methods. Through recent advances in low power consumption RF transmitters and sensors, it is possible to adopt a micro-power energy harvesting system realized by MEMS technology for the system-on-chip. However, the MEMS energy harvesting system has some drawbacks such as a high natural frequency over 300 Hz and a small power generation due to a small dimension. To overcome these limitations, we devised a novel power generator with a spiral spring structure as shown in the figure. The natural frequency of a cantilever could be decreased to the usable frequency region (under 300 Hz) because the natural frequency depends on the length of a cantilever. In this study, the natural frequency of the energy harvester was a lower than a normal cantilever structure and sufficiently controllable in 50 - 200 Hz frequency region as adjusting weight of a proof mass. Moreover, the MEMS energy harvester had a high energy conversion efficiency using a shear mode ($d_{15}$) is much larger than a 33 mode ($d_{33}$) and the energy conversion efficiency is proportional to the piezoelectric constant (d). We expect the spiral type MEMS power generator would be a good candidate for a standalone power generator for USN.

• ALGAE
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• 제39권2호
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• pp.109-127
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• 2024

High production and efficient harvesting of microalgae containing high omega-3 levels are critical concerns for industrial use. Aeration can elevate production of some microalgae by providing CO₂ and O₂. However, it may lower the production of others by generating shear stress, causing severe cell damage. The mixotrophic dinoflagellate Gymnodinium smaydae is a new, promising microalga for omega-3 fatty acid production owing to its high docosahexaenoic acid content, and determining optimal conditions and methods for high omega-3 fatty acid production and efficient harvest using G. smaydae is crucial for its commercial utilization. Therefore, to determine whether continuous aeration is required, we measured densities of G. smaydae and the dinoflagellate prey Heterocapsa rotundata in a 100-L semi-continuous cultivation system under no aeration and continuous aeration conditions daily for 9 days. Furthermore, to determine the optimal conditions for harvesting through centrifugation, different rotational speeds of the continuous centrifuge and different flow rates of the pump injecting G. smaydae + H. rotundata cells into the centrifuge were tested. Under continuous aeration, G. smaydae production gradually decreased; however, without aeration, the production remained stable. Harvesting efficiency and the dry weights of omega-3 fatty acids of G. smaydae + H. rotundata cells at a rotational speed of 16,000 rpm were significantly higher than those at 2,000-8,000 rpm. However, these parameters did not significantly differ at injection pump flow rates of 1.0-4.0 L min^-1. The results of the present study provide a basis for optimized production and harvest conditions for G. smaydae and other microalgae.

• 한국정보통신학회논문지
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• 제15권11호
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• pp.2457-2464
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• 2011

본 논문에서는 압전 소자를 이용한 진동에너지 하베스팅 회로를 설계하였다. 압전소자의 전력-전압 특성을 이용하여 최대 전력을 부하로 전달하기 위한 MPPT(Maximum Power Point Tracking) 제어 기능을 구현하였다. MPPT 제어 회로는 압전소자의 출력 단에 연결된 전파 정류회로의 개방회로 전압을 주기적으로 샘플링하여 최대 가용전력이 생성되는 지점을 추적하고 이를 부하로 전달하는 역할을 한다. 제안된 진동에너지 하베스팅 회로는 $0.18{\mu}m$ CMOS 공정으로 설계하였다. 모의실험 결과 설계된 회로의 최대 전력 효율은 91%이고, pad를 제외한 칩 면적은 $700{\mu}m{\times}730{\mu}m$이다.

• 한국정보통신학회논문지
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• 제16권11호
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• pp.2487-2494
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• 2012

본 논문에서는 MPPT 제어 기능을 갖는 열에너지 하베스팅 회로를 설계하였다. MPPT(Maximum Power Point Tracking) 제어는 열전소자의 개방회로전압과 MPP 전압간의 관계를 이용하였으며 열전소자의 개방회로전압을 주기적으로 샘플링 함으로써 이를 이용해 MPPT 기준전압을 생성하여 이를 기준으로 부하로의 에너지 공급을 제어한다. 모의실험 결과 94%의 최대 전력 효율을 보였다. 제안된 열에너지 하베스팅 회로는 $0.35{\mu}m$ CMOS 공정으로 설계하였으며 설계된 칩 면적은 PAD를 제외하고 $1168.7{\mu}m{\times}541.3{\mu}m$이다.