• International Journal of Aeronautical and Space Sciences
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• 제16권3호
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• pp.407-417
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• 2015

Recently, piezo-aeroelastic energy harvesting has received greater attention. In the present study, a piezo-aeroelastic energy harvester using a nonlinear trailing-edge flap is proposed, and its nonlinear aeroelastic behaviors are investigated. The energy harvester is modeled using a piezo-aeroelastic model of a two-dimensional typical section airfoil with a trailing-edge flap (TEF). A piezo-aeroelastic analysis is carried out using RL and time-integration methods, and the results are verified with the experimental data. The linearizing method using a describing function is used for the frequency domain analysis of the nonlinear piezo-aeroelastic system. From the linear and nonlinear piezo-aeroelastic analysis, the limit cycle oscillation (LCO) characteristics of the proposed energy harvester with the nonlinear TEF are investigated in both the frequency and time domains. Finally, the authors discuss the air speed range for effective piezo-aeroelastic energy harvesting.

• 한국위성정보통신학회논문지
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• 제10권2호
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• pp.10-13
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• 2015

본 논문에서는 네트워크 에너지 하베스팅 효율 향상을 위한 새로운 사용자 정보 피드백 알고리즘을 제안한다. 제안된 알고리즘은 방사되는 에너지 대비 수신되는 하베스팅 에너지 양의 증가폭을 중요한 하베스팅 파라미터인 임계점 와 비교하고 에너지 하베스팅 유저를 결정하는데 중점을 둔다. 이 방법을 이용하면 비효율적으로 방사되는 에너지 낭비를 막아 전체 네트워크의 에너지 하베스팅 효율을 증가 시킨다. 본 논문의 실험결과는 사용자 피드백 알고리즘을 이용해서 계산된 네트워크 유저의 하베스팅 에너지 양의 증가폭을 임계점 =15%와 비교해서 에너지 하베스팅 유저를 결정했을 때 전체 네트워크의 에너지 하베스팅 효율이 가장 높게 증가한 다는 것을 입증하였다.

• 한국작물학회지
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• 제45권1호
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• pp.55-58
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• 2000

Germination of sweet and super sweet corn is lower than normal corn due to the higher sugar and lower starch contents of kernels. Sweet corn seeds are easily deteriorated in the field under the unfavorable condition, therefore it is important to identify the optimal harvesting time for seed production. This trial was conducted to investigate the responses of germination percentage of shrunken-2(sh2), brittle(bt), sugary(su), and sugary enhancer(se) hybrids in relation to harvesting dates. Eight hybrids of four different gene sweet corns were harvested at 15, 20, 25, 30, 35, 40, 45, and 50 days after silking(DAS). Germination test was performed using paper towel method. Mean germination percentages across eight hybrids showed the highest value at 45 DAS. There were significant differences among genes and within gene for germination. Shrunken-2 hybrid Mecca was higher than su hybrids for germination, indicating that sh2 would not be poorer than su Late harvesting beyond the optimal harvesting date might not be desirable because of more lodging and ear rots. Theoretical optimal harvesting date estimated from the regression equation was 40.9 DAS, however, practical date for harvesting would be a few days later than the estimated date if seedling vigor might be considered. Kernel dry weight per ear showed similar response to germination. Regression equation showed the highest kernel dry weight at 40.7 DAS. Significant correlations between kernel dry weight and germination were observed, impling that kernel dry matter accumulation would be an important factor for germination.

• 한국작물학회지
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• 제51권spc1호
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• pp.224-228
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• 2006

남부지역에서 고품질의 택사를 생산하기 위하여 적정 수확시기와 적정 건조온도를 검토하기 위하여 2004년부터 2006년까지 택사 선월종과 용전종을 공시하여 실험을 수행하였는데 그 결과를 요약하면 다음과 같다. 1. 첫 서리(초상) 후 22일 만인 12월 29일에 수확함으로서 선월종과 용전종이 수량성이 가장 높았고 품질에서도 회전식 박피기에서 박피한 결과 완전한 백색의 택사로 광택이 뚜렷하여 우수하였다. 2. 택사 수확 후 건조기 내에서 1주야로 7일간 $35-40^{\circ}C$ 건조할 때에 알맹이 택사(껍질이 벗겨진 박피된 택사)의 수량성이 가장 높았고 품질에서도 완전한 백색의 택사로 광택이 뚜렷하여 우수하였다. 따라서 택사의 품질 향상을 위해서는 첫 서리(초상)후 29일에 수확하고 건조는 $35-40^{\circ}C$ 건조기 내에서 1주일 건조함이 타당하리라고 생각된다.

• Journal of Biosystems Engineering
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• 제2권1호
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• pp.56-80
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• 1977

This experimental work was conducted in order to find out the optimum time of harvest of Japonica-type (Akibare) and Indica-type(Tong-il) rice variety for three harvesting systems by investigating the harvesting losses and milling quality. The study was also concerned about the nature and amount of grain losses incurred during the each sequence of post-harvest technologies, and based on these result, a modification of existing systems giving a minimum grain loss was attempted. Binder, combine, and traditional systems were tested in this study and five grain moisture levels were disposed according to the decrease of grain moisture . The results are summarized as follows ; 1. The total losses of Akibare variety were ranged from 1.1 to 1.5 per cent for the traditional harvesting system , 2.1 to 4.8 per cent for the harvesting system by use of binder, and 2.8 to 4.3 per cent for the harvesting system by use of combine as the grain moisture content was reduced from 24 to 15 percent. Milling recovery of the harvesting system by use of binder, 74.8 ∼75.7 percent, was a little higher as it was compared to that of traditional harvesting system, 74.3 ∼75.0per cent, and that of the harvesting system by use of combine, 73.8 ∼75.0 per cent. Head rice recovery of mechanically dried paddy samples was higher than that of sun-dried paddy samples. 2. The total losses of Tong-il variety were ranged from 3.8 to 5.0 per cent for the traditional harvesting system, 5.2 to 10.0 percent for the system by use of binder, and 3.0 to 5.0 per cent for the system by use of combine as the grain moisture was reduced from 28 to 16 per cent. 3. Milling recovery of Tong-il variety harvested by the traditional harvesting system was 72.3 ∼73.6 percent and it was lower when compared to that of 72.3∼75.0 per cent harvested by binder, and 73.0∼74.6 percent harvested by combine. 4. Head rice recovery of Tong-il variety harvested by the traditional harvesting system (58.

• 한국작물학회지
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• 제58권1호
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• pp.28-35
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• 2013

Anthocyanin pigments from three pigmented rice varieties, Hongjinju, Sintoheugmi and Josaengheugchal pigmented by black color, were quantified to evaluate effects of transplanting and harvesting time during seed development. Hongjinju, a rice variety of grains pigmented by red color, contains only two kinds of anthocyanins, delphinidin and cyanidin. Meanwhile, delphinidin, cyanidin, and pelargonidin were identified in Sintoheugmi and Josaengheugchal. Anthocyanidin contents in pigmented rice variety Hongjinju under different planting times were decreased with prolonged harvesting times. The Sintoheukmi showed that cyanidin content was the highest among analyzed pigments during seed development. Two anthocyanins (cyanidin and pelargonidin) in Josaengheugchal recorded highest contents at 20 days after heading in three transplanting times. Cyanidin content was also slightly increased with prolonged transplanting time. Total anthocyanidin contents in Hongjinju were always lower than that of Sintoheukmi and Josaengheukchal. In two rice varieties, Sintoheugmi and Josaengheugchal, $a^*$ values were commonly slightly decreased by late transplanting and harvesting times. Changes of $a^*$ and $b^*$ values in waxy rice varieties, Sintoheugmi and Josaengheugchal varied more than those in Hongjinju. In Josaengheugchal, early harvesting before maturity showed lower brown rice yield and late harvesting in the each transplanting times resulted in highest brown rice yield.

• 대한기계학회논문집B
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• 제35권9호
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• pp.955-960
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• 2011

본 연구에서는 실시간 무선 철도시스템 모니터링을 위하여 열차 주행에 따라 발생하는 열 및 진동 에너지를 전기자원화 하는 신재생 에너지 개념의 전력원인 자가발전 구동 기술에 대한 철도시스템 적용 가능성을 확인하였다. 이를 위해 실제 주행 중인 고속열차를 이용하여 철도차량의 운행환경 하에서 발생하는 열에너지와 진동에너지를 실측하여, 주행 중 이들 에너지 발생량 및 변화를 분석하고 이를 통해 진동 및 열 에너지를 이용하는 자가발전 모듈의 예측 전력량을 계산하고, 이 전력량에 대한 이 모니터링 시스템 적용 가능성에 대한 연구를 수행하였다.

• Journal of Biosystems Engineering
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• 제7권2호
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• pp.36-44
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• 1983

Farm population was rapidly decreasing due to shift of the people from farm sector to the non-farm sector caused by the economic growth of the country. Especially, a great shortage of farm labor in busy farming period in June and October is becoming a serious problem in maintaining or promoting land productivity. The peak of labor requirement in summer is caused by rice transplanting and barley harvesting. In order to reduce the restrictions imposed on farm management by the concurrence of labor requirement and the lack of labor, the experimental study for mechanization of barley harvesting has been carried out in the fields. 1. The machines for barley harvesting were knap-sack type reapers, windrow reaper (power tiller attachment), binder and combine. The order of higher efficiency of machine for barley harvesting was combine, binder, windrow reaper (WR), knapsack type reaper 1(KSTR1), and knap sack type reaper 2(KSTR2; mist and duster attachment). 2. The ratio of grain loss for the manual, binder, and combine plot was about four percent of total field yield. 3. The total yield of barley in 35 days and 40 days harvesting after heading were 514 kg and 507kg per 10 ares respectively. The yield of 35 days-plot was higher than other experimental plots. 4. The lowest yield was recorded in 30 days-plot due to the large quantity of immatured grains and having lighter 1000-grain weight. The ratio of immatured grains was 2.66 percent and 1000-grain weight was 29.4 grams. 5. The total harvesting cost of the windrow reaper was 10,178 won per 10 ares. It was the lowest value compared to other machines. The next were combine, binder, KSTR1, KSTR2, and manual in sequence. As a result, the optimum time of barley harvesting for mechanization was 35-40 days after heading. Combine, binder, and windrow reaper were recommended as the suitable machines for barley harvesting in the work efficiency. However, in total harvesting cost, the windrow reaper was the most promising machine for barley harvesting.

• 한국작물학회지
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• 제53권2호
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• pp.125-130
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• 2008

본 연구는 주요 조생종 콩의 생육과 종실품질 및 수량을 비교하여 남부지방 다모작 재배농가의 조생종 콩 품종선택에 활용하고자 전남 나주(위도 35^{\circ}04'N, 경도 126^{\circ}54'E)에서 6월 15일에 파종하여 수행하였다. 큰올콩과 화성풋콩은 성숙기가 9월 12일로 빨라 작부체계 도입에 유리할 뿐만 아니라 종실품질과 수량이 양호하였다. 그리고 새올콩과 신록콩은 성숙기가 9월 20일 전.후로 조금 늦으나 종실품질이 좋고 수량이 많았다. 따라서 콩 후작물을 9월 중순에 파종하고자 할 때는 큰올콩과 화성풋콩이, 9월 하순에 파종하고자 할 때는 새올콩과 신록콩이 유리하였다. 그리고 주요 조생종 콩의 조기수확에 따른 종실품질과 수량성 등을 검토하여 조기수확 한계기를 구명하고자 수행하였다. 큰올콩은 수확적기(9월 12일)보다 6일전(9월 6일)에 수확할 때 입중, 수량, 종실품질 등이 적기수확과 차이가 없었다. 한편 새올콩은 수확적기(9월 24일)보다 6일전(9월 18일)에 수확할 때 입중, 수량, 종실품질 등이 적기수확과 차이가 없다. 따라서 큰올콩과 새올콩의 안정적인 조기수확 한계기는 수확적기 6일 전이다.

• 한국위성정보통신학회논문지
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• 제11권2호
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• pp.55-59
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• 2016

기존 무선에너지 하비스팅시스템에서 유저는 하나의 Hybirid-AP (H-AP)로부터 에너지와 정보를 동시에 받았다. 하지만 무선에너지 하비스팅은 거리가 멀수록 감쇄가 심하기 때문에 H-AP에서 거리가 먼 유저들은 낮은 하비스팅 효율 가진다 (이중 근거리/원거리 문제). 이러한 문제를 해결하기 위해서 본 논문은 Power beacon (PB)을 통해 유저에게 별도의 파워를 공급하는 비결합 무선에너지 하비스팅 네트워크를 시스템 모델로 사용하였다. 이 논문의 주된 목적은 다양한 제약 조건과 Quality of service (QoS), 그리고 Quality of harvested power (QoP)를 만족하면서 목적 함수인 Energy efficiency (EE)를 최대화 하는 것이다. 제안된 시스템은 라그랑지안 쌍대 분해법 이론을 기반으로 EE 최대화를 위한 최적의 시간 스케줄링 알고리즘을 제안한다. 이 알고리즘을 통해 프레임 분해 요소, H-AP의 송신파워, 그리고 PB의 송신파워의 최적 값과 EE의 최대값을 구할 수 있다. 모의 실험 결과는 제안된 알고리즘으로 파라미터가 최적 값으로 빠르게 수렴하고 제안된 모델의 성능이 기존의 시스템 모델보다 우수하다는 것을 증명한다.