• 한국작물학회지
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• 제47권3호
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• pp.157-160
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• 2002

삼백초의 근경 수확방법을 인력수확에서 생력기계화 수확기술로 개선코자 트랙터부착 굴취기 등 4종의 수확기기의 기계수확 효율을 비교, 검토하였던 바 그 결과를 요약하면 다음과 같다. 1. 총생력시간은 인력에 비하여 경운기 경운 60%, 경운기부착 굴취기 64%, 트랙터부착 굴취기 67%절감되었다. 2. 근경의 손실율은 인력수확 13.9%, 경운기 경운 11.7%, 경운기부착 굴취기 9.8%, 트랙터부착 굴취기 5.1%로 기계수확에서 낮았다. 3. 상품 근경수량은 인력수확 3,032 kg/10a에 비하여 경운기 경운은 248 kg 감소하였으나, 경운기부착 굴취기와 트랙터부착 굴취기는 56kg, 320kg각각 증가되었으며, 총 근경수량은 인력수확에 비하여 기계수확에서 3-10%증가되었는데, 트랙터부착 굴취기는 10%의 증가로 가장 높은 수량을 보였다. 4. 경제성은 인력수확에 비하여 기계수확에서 13-27%높았으며, 트랙터 부착 굴취기는 27%로 가장 높았다. 5. 트랙터부착 굴취기는 생력효율, 상품수량, 총 근경수량 그리고 경제성에서 가장 높거나, 많은 것으로 나타나 적용가능성이 가장 높은 것으로 나타났다.

• 수산경영론집
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• 제46권2호
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• pp.59-74
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• 2015

This study aims to estimate optimal harvesting production, fishing efforts, and stock levels of yellow croaker caught by the offshore Stow Net and the offshore Gill Net fisheries using the current value Hamiltonian method and the surplus production model. As analyzing processes, firstly, this study uses the Gavaris general linear model to estimate standardized fishing efforts of yellow croaker caught by the above multiple fisheries. Secondly, this study applies the Clarke Yoshimoto Pooley(CY&P) model among the various exponential growth models to estimate intrinsic growth rate(r), environmental carrying capacity(K), and catchability coefficient(q) of yellow croaker which inhabits in offshore area of Korea. Thirdly, the study determines optimal harvesting production, fishing efforts, and stock levels of yellow croaker using the current value Hamiltonian method which is including average landing price of yellow croaker, average unit cost of fishing efforts, and social discount rate based on standard of the Korean Development Institute. Finally, this study tries sensitivity analysis to understand changes in optimal harvesting production, fishing efforts, and stock levels of yellow croaker caused by changes in economic and biological parameters. As results drawn by the current value Hamiltonian model, the optimal harvesting production, fishing efforts, and stock levels of yellow croaker caught by the multiple fisheries were estimated as 19,173 ton, 101,644 horse power, and 146,144 ton respectively. In addition, as results of sensitivity analysis, firstly, if the social discount rate and the average landing price of yellow croaker continuously increase, the optimal harvesting production of yellow croaker increases at decreasing rate and then finally slightly decreases due to decreases in stock levels of yellow croaker. Secondly, if the average unit cost of fishing efforts continuously increases, the optimal fishing efforts of the multiple fisheries decreases, but the optimal stock level of yellow croaker increases. The optimal harvest starts climbing and then continuously decreases due to increases in the average unit cost. Thirdly, when the intrinsic growth rate of yellow croaker increases, the optimal harvest, fishing efforts, and stock level all continuously increase. In conclusion, this study suggests that the optimal harvesting production and fishing efforts were much less than actual harvesting production(35,279 ton) and estimated standardized fishing efforts(175,512 horse power) in 2013. This result implies that yellow croaker has been overfished due to excessive fishing efforts. Efficient management and conservative policy on stock of yellow croaker need to be urgently implemented.

• 스마트미디어저널
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• 제4권1호
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• pp.25-32
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• 2015

Powering wireless sensors with energy harvested from the environment is coming of age due to the increasing power densities of both storage and harvesting devices and the electronics performing energy efficient energy conversion. In order to maximize the functionality of the wireless sensor network, minimize missing packets, minimize latency and prevent the waste of energy, problems like congestion and inefficient energy usage must be addressed. Many sleep-awake protocols and efficient message priority techniques have been developed to properly manage the energy of the nodes and to minimize congestion. For a WSN that is operating in a strictly energy constrained environment, an energy-efficient transmission strategy is necessary. In this paper, we present a novel transmission priority decision scheme for a heterogeneous body sensor network composed of normal nodes and an energy harvesting node that acts as a cluster head. The energy harvesting node's decision whether or not to clear a normal node for sending is based on a set of metrics which includes the energy harvesting node's remaining energy, the total harvested energy, the type of message in a normal node's queue and finally, the implementation context of the wireless sensor network.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.429-432
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• 2017

본 논문에서는 고성능 비교기를 이용한 전파정류 애너지 하베스팅 회로를 설계하였다. 설계된 회로는 크게 Negative Voltage Converter, Active Diode단으로 나뉜다. 그리고 Active Diode단에 포함된 비교기는 3-stage 형태로 구현 하였으며 Pre-amplification, Decision circuit, Output buffer단으로 나뉜다. 이 비교기는 Propagation delay를 줄이고 하베스팅 회로의 전압 및 전력 효율을 향상 시키는 것이 주된 목적이다. 제안된 회로는 Magna $0.35{\mu}m$ CMOS 공정으로 설계하였으며, 모의실험을 통해 동작을 검증하였다. 설계된 에너지 하베스팅 회로의 칩 면적은 $612{\mu}m{\times}444{\mu}m$이다.

• 드라이브 ㆍ 컨트롤
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• 제21권2호
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• pp.65-71
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• 2024

In this study, we suggested a key-point detection method for robot harvesting of oriental melon. Our suggested method could be used to detect the detachment part and major composition of oriental melon. We defined four points (harvesting point, calyx, center, bottom) based on tomato with characteristics similar to those of oriental melon. The evaluation of estimated key-points was conducted by pixel error and PDK (percentage of detected key-point) index. Results showed that the average pixel error was 18.26 ± 16.62 for the x coordinate and 17.74 ± 18.07 for the y coordinate. Considering the resolution of raw images, these pixel errors were not expected to have a serious impact. The PDK score was found to be 89.5% PDK@0.5 on average. It was possible to estimate oriental melon specific key-point. As a result of this research, we believe that the proposed method can contribute to the application of harvesting robot system.

• 한국전기전자재료학회논문지
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• 제24권5호
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• pp.416-421
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• 2011

Nowadays, the increasing demands upon mobile devices such as wireless sensor networks and the recent advent of low power electrical devices such as MEMS make such renewable power sources attractive. A vibration-driven MEMS lead zirconate titanate $Pb(Zr,Ti)O_3$ (PZT) cantilever device is developed for energy harvesting application. This paper presents a piezoelectric based energy harvester which is suitable for power generating from conventional vibration and has in providing energy for low power electron ic devices. The PZT cantilever is used d33 mode to get the electrical power. The PZT cantilever based energy harvester with the dimension of 7 mm${\times}$3 mm${\times}$0.03 mm is fabricated using micromachining technologies. This PZT cantilever has the mechanical resonance frequency with a 900 Hz. With these conditions, we get experimentally the 37 uW output power from this device with the application of 1g acceleration using the 900 Hz vibration. From this study, we show the feasibility of one of energy harvesting candidates using PZT based structure. This PZT energy harvester could be used for various applications such a batteryless micro sensors and micro power generators.

• 한국전기전자재료학회논문지
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• 제27권11호
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• pp.740-745
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• 2014

ZnO nanowires were grown by hydrothermal synthesis process and piezoelectric poly vinylidene fluoride (PVDF) was then coated on top of the ZnO-nanowires by spray-coating technique. The composite layer of ZnO-nanowires/PVDF was applied to an energy harvesting device based on piezoelectric-conversion mechanism. A defined mechanical force was given to the nanogenerator device to evaluate their electric power generation characteristics, where output current density and voltage were examined. Electric power generation property of the ZnO-nanowires/PVDF based nanogenerator device was compared to that of the nanogenerator device with ZnO-nanowires as single active layer. Effect of the ZnO-nanowires on improvement of power generation was discussed to examine its feasibility for the nanogenerator device.

• 문화기술의 융합
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• 제6권3호
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• pp.361-367
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• 2020

본 논문은 초소형 디바이스 분야에서 사용될 수 있는 배터리가 없는 초저전력 자가발전 협업 신경망 시스템을 제공하는 디바이스에 대하여 설명한다. 본 디바이스는 외부에서 전력을 공급하지 않더라도 동작하며, 다른 신경망과 협업하여 대규모의 신경망 구축이 가능하다. 해당 디바이스는 에너지 하베스팅 모듈을 탑재하고 있어 공간적 제약 없이 어느 곳에서나 자가발전을 이용하여 사용이 가능하며, 디바이스 내부의 신경만을 가지고도 동작할 수 있지만 상황에 따라 네트워크를 통해 대규모의 신경망의 일부로 사용하는 것도 가능하다.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2019년도 제60차 하계학술대회논문집 27권2호
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• pp.159-160
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• 2019

일반적인 FOCV MPPT는 VOC와 VMPP와의 관계인 ${\alpha}$를 외부에서 지정해준다. 하지만 외부환경 (조도나 온도)에 따라서 태양전지의 ${\alpha}$값이 변화할 가능성이 있다. 본 논문에서는 저전력 IoT 센서의 구동을 위한 태양열 에너지 하베스팅을 위해 IV Curve를 이용한 태양전지 전력 계싼회로를 제안한다. IV Curve를 이용한 태양전지 전력을 직접 계산하여 FOCV MPPT를 개선함으로써 보다 높은 효율의 MPPT가 가능하고 외부환경의 변화에도 충분히 Maximum Power Point Tracking이 가능해지게 된다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권1호
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• pp.319-333
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• 2022

In order to enhance system energy efficiency, bidirectional link resource allocation strategy in GFDM-based multiuser SWIPT systems is proposed. In the downlink channel, each SWIPT user applies power splitting (PS) receiver structure in information decoding (ID) and non-linear energy harvesting (EH). In the uplink channel, information transmission power is originated from the harvested energy. An optimization problem is constructed to maximize weighted sum ID achievable rates in the downlink and uplink channels via bidirectional link power allocation as well as subcarriers and subsymbols scheduling. To solve this non-convex optimization problem, Lagrange duality method, sub-gradient-based method and greedy algorithm are adopted respectively. Simulation results show that the proposed strategy is superior to the fixed subcarrier scheme regardless of the weighting coefficients. It is superior to the heuristic algorithm in larger weighting coefficients scenario.