• 한국전기전자재료학회논문지
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• 제24권6호
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• pp.515-518
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• 2011

In this work, we designed and fabricated a multilayer thin film Pb(Zr,Ti)$O_3$ cantilever with a Si proof mass for low frequency vibration energy harvesting applications. A mathematical model of a mu lti-layer composite beam was derived and applied in a parametric analysis of the piezoelectric cantilever. Finally, the dimensions of the cantilever were determined for the resonant frequency of the cantilever. W e fabricated a device with beam dimensions of about 4,930 ${\mu}M$ ${\times}$ 450 ${\mu}M$ ${\times}$ 12 ${\mu}M$, and an integrated Si proof mass with dimensions of about 1,410 ${\mu}M$ ${\times}$ 450 ${\mu}M$ ${\times}$ 450 ${\mu}M$. The resonant frequency, maximum peak voltage, and highest average power of the cantilever device were 84.5 Hz, 88 mV, and 0.166 ${\mu}Wat$ 1.0 g and 23.7 ${\Omega}$, respectively. The dimensions of the cantilever were determined for the resonance frequency of the cantilever.

• 한국연초학회지
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• 제22권2호
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• pp.114-122
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• 2000

This study was carried out to investigate the changes in the composition of essential oils for the improvement of air-curing process of burley tobacco leaves. From the essential oils isolated from the cured tobacco leaves by steam distillation method, 90 compounds including 15 acids and esters, 19 alcohols, 23 aldehydes and ketones, 19 hydrocarbons, and 14 miscellaneous compounds, could be identified by gas chromatography and gas chromatography-mass spectrometry. Among them, acids and esters were gradually decreased during the progress of curing after harvesting. A rapid increase in alcohol content was observed in the earlier stage of curing, but thereafter, decrease followed until the end of curing However, aldehyde and ketone groups were continuously increased during curing and were 3 times higher in quantity after curing than at the harvesting time. The concentration of hydrocarbons was increased in the earlier stage of curing, but gradually decreased from the middle stage. The miscellaneous compounds were continuously increased in content until the end stage of curing, with rapid increased in the earlier stage of curing.

• 한국산림과학회지
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• 제105권4호
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• pp.456-462
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• 2016

본 연구는 임도의 목재수확작업에서의 활용효과에 대한 실증적 구명을 위해 5개 지방산림청 8개 경영계획구의 실행자료를 토대로 목재수확작업에서의 임도시설 전 후의 접근성 변화와 비용절감 효과를 분석하였다. 분석 결과, 임도 및 공도로부터 500 m 이내 목재수확 작업의 사업실행 면적은 임도 시설 전 평균 25.2%에서 시설 후 평균 88.3%로 약 3.5배 증가하였으며, 임도 시설에 따른 목재수확작업 비용 절감효과는 평균 308천원/km/년인 것으로 나타났다. 이에 임도시설이 목재수확작업을 위한 접근성 개선 및 작업비용 절감효과가 큰 것으로 나타났으며, 임도 시설확충을 위한 지속적 정책추진이 필요할 것으로 판단된다.

• 드라이브 ㆍ 컨트롤
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• 제16권4호
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• pp.74-79
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• 2019

In this study, an edible fresh corn harvest testing machine was designed and manufactured. And harvesting performance was analyzed through the field test. The testing machine is of the tractor attached type. It is connected to the tractor PTO shaft to transfer power to the each part of the harvesting machine. And it harvests fresh corn by one row through the processes of cutting, stem crushing, detaching, and collecting. The performance test was performed at PTO speed (540, 750, 1050 rpm, respectively), working speed (0.1, 0.15, 0.2 m/s, respectively), and cropping cultivation (row spacing·hill spacing 70·25 cm, 70·40 cm, 90·30 cm, respectively). The performance test was repeated three times in the 15 m section. The detachment loss ratio, uncollected crop ratio, damage ratio, and harvest ratio were analyzed. As a result of the performance test, it was analyzed that the PTO speed 540 rpm, running speed of 0.1 m/s, and row spacing·hill spacing 70·40 cm were the optimal condition.

• 한국식품영양학회지
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• 제27권2호
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• pp.194-202
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• 2014

This study investigates the chemical compositions of Aster koraiensis Nakai essential oils and the quantitative changes of major terpene compounds according to various harvesting times. The essential oils obtained by hydrodistillation from the aerial parts of Aster koraiensis Nakai are being analyzed by GC and GC-MS. The essential oil compositions of Aster koraiensis Nakai are characterized byhigher contents of sesquiterpene compounds. Ninety-seven volatile flavor compounds are being identified in the essential oils from Aster koraiensis Nakai harvested in 2010, and caryophyllene oxide (8.38%), aristolene (7.08%), epiglobulol (5.57%), and ethyl furanone (4.73%) are the most abundant compounds. Ninety-five compounds are identified in the essential oils from the plants harvested in 2011, and aristolene (11.56%), calarene (9.33%), phytol (8.28%), ethyl furanone (7.63%), and epiglobulol (7.18%) are the most abundant compounds. Ninety-five compounds are being identified in the essential oils from the plants harvested in 2012, and calarene (15.3%), aristolene (14.24%), ethyl furanone (7.21%), phytol (6.98%) are the major compounds. The contents of aristolene, ${\alpha}$-caryophyllene, ${\alpha}$-muurolene, ${\alpha}$-calacorene, aromadendrene oxide, and calarene increase significantly from 2010 to 2012. The contents of ${\alpha}$-cubebene, isocaryophyllene, and diepi-${\alpha}$-cedrene epoxide decrease significantly from 2010 to 2012. The quantitative changes of aristolene and calarene according to harvesting time can be served as a quality index of the Aster koraiensis Nakai essential oils.

• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.593-601
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• 2020

This study was conducted to analyze the physical strain with heart rate monitor in timber harvesting operations in order to reduce occupational accidents. The timber harvesting activities are manual cutting(felling, limbing and bucking) with a chainsaw and extraction by cable yarder. The study took place on Japanese larch stand. The average height was 26m and average diameter at breast height(DBH) was 3 7cm. The havest unit was gentle slope to steep slope. Results showed that the heart rate increases for chocking, felling, limbing and bucking were 94.0%, 87.9%, 84.8% and 56.4% respectively. The rate of Work Load Index was higher in the limbing(61.4%) activity than other activities chocking(55.2%), felling(54.1%) and bucking(32.1%). During 50% working heart rate test it was found that limbing(1.09), chocking(1.05) and felling(1.04) was exposed to high work intensity compared to bucking(0.83). The results showed that maximum acceptable work times(felling, chocking and limbing) were 2.30 hour, 1.85 hour and 1.60 hour respectively. To avoid occupational accidents, timber harvest workers may use a suitable working hour schedule to felling, chocking, limbing.

• Journal of Biosystems Engineering
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• 제43권4호
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• pp.296-302
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• 2018

Purpose: The aim of this study was to determine appropriate threshing and selection conditions for sorghum harvesting using a rice combine-harvester. Methods: Sorghum harvesting performance was tested using an actual rice combine. Through this test, the grain loss rate and the composition of crops according to the engine and fan speeds of the combine were investigated. Furthermore, the optimal threshing and selection conditions were determined by carrying out a harvest test based on the opening size factor of the concave in a test field. Results: The grain loss rate for the sorghum using a concave ($18{\times}18mm$) of the rice combine was the lowest at 0.1% at a chaffer angle of $40^{\circ}$, engine speed of 2000 rpm, and fan speed of 20 m/s, but the sorting sieve clogged frequently. Furthermore, as the engine speed and fan speed increased, the grain loss rate also increased. The sorghum harvesting test results of the combine according to the concave opening size showed that the grain loss rate was 0.5% at a driving speed of 0.5 m/s, with a concave opening diameter of 13 mm, a chaffer angle of $40^{\circ}$, a concave sieve oscillation frequency of 4.8 Hz, a fan speed of 20 m/s, and an engine speed of 2000 rpm. Conclusions: Findings showed that sorghum could be harvested using a head feeding rice combine.

• 전자공학회논문지SC
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• 제48권2호
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• pp.15-21
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• 2011

본 논문에서는 $0.35{\mu}m$ CMOS 공정을 이용하여 태양 에너지 하베스팅을 위한 에너지 관리 시스템을 설계하였다. 태양 에너지 관리 시스템은 ISC(Integrated Solar Cell), voltage booster, MPPT(Maximum Power Point Tracker) control unit으로 구성된다. ISC의 개방전압은 약 0.5V이고, 단락 전류는 약 $15{\mu}A$이다. Voltage booster는 뒷단에 약 1.5V로 승압된 전압을 공급한다. MPPT control unit은 ISC가 MPP점에 도달 하였을 때, load로 전력이 전달될 수 있도록 pMOS 스위치를 동작시킨다. SEMU(Solar Energy Management Unit)의 크기는 패드를 포함하여 $360{\mu}m{\times}490{\mu}m$이다. ISC의 면적은 $500{\mu}m{\times}2000{\mu}m$이다. 제작된 칩을 측정한 결과 설계된 SEMU가 ISC에서 수확된 에너지에 대해 MPPT control 동작을 제대로 수행하는 것을 확인하였다. 측정된 MPP 전압범위는 약 370mV∼420mV이다.

• Journal of Biosystems Engineering
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• 제38권4호
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• pp.240-247
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• 2013

Purpose: This study was conducted to develop a rubber-crawler type vehicle as a traveling device for harvesting water-dropwort cultivated in water contained paddy rice field in winter season. Methods: A commercial rubber-crawler type vehicle was used to investigate application of rubber crawler to the paddy rice field as preliminary test. As the result of the preliminary test, a both prototype traveling device with rubber crawlers for a water-dropwort harvest was designed with inclination of $45^{\circ}$ at the front-end and rear-end of crawler under the basic water depth of 0.6 m in the paddy rice field. The device was fabricated and attached to the experimental harvesting test devices on the front of the prototype vehicle. The size of the prototype crawler vehicle with a harvesting part is $2,800{\times}1,460{\times}1,040 $ (mm) ($L{\times}W{\times}H$) with weight of 9.21 kN (maximum). Sizes of the crawler of prototype vehicle are ground contact length of 900 mm, width of 180 mm, height of 1,070 mm and distance between center to center of crawlers of 720 mm. The side-overturn angle of the prototype was $26.4^{\circ}$. Results: Driving performance of the prototype vehicle in water contained paddy field were good at both forward and reverse (backward) directions as weights were applied. The drawbar pull and the maximum sinking depth of the prototype vehicle were 3.5 kN and 0.13 m respectively at water depth of 0.5 m, when the weight and bearing capacity of the prototype rubber crawler in the paddy field were 8.51 kN and 26.3 $kN/m^2$, respectively. Conclusions: Results of the driving test performance of the prototype crawler in paddy rice field at the water depth of 0.5 m were satisfactory. The prototype had enough drawbar pull and driving ability in the deep water contained paddy field.

• 한국작물학회지
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• 제27권2호
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• pp.123-129
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• 1982

답리작 맥류 재배지대에 있어서 수량과 품질등이 저하되지 않으면서 조기에 수확할 수 있는 안전 한계기를 구명하고자 백동과 올밀을 공시하여 출수후 25일부터 5일 간격으로 6회 수확하였던 바 그 결과를 요약하면 다음과 같다. 1. 백동에 있어서 립장은 출수후 20일, 립폭은 30일, 립후는 35일경에 최대에 달하였으며, 올밀은 이보다 5일 정도 각각 늦은 경향이었다. 2. 1,000립중이 일정하게 되어 생리적 성숙기로 볼 수 있는 시기는 백동은 출수후 35일경, 올밀은 40일경이었으며, 수량도 이 시기에 가장 많았다. 3. 백동과 올밀에 있어서 수중에 대한 입중비율은 출수후 7일에는 57%와 74%, 수축비율은 7%와 15%로서 올밀이 백동보다 현저히 높았으나, 성숙기에는 서로 비슷하였으며, 이삭의 각 기관별 대 수중비율이 일정하게 되는 시기는 백동은 출수후 35일, 올밀은 40일경이었다. 4. 곡립 수분함량은 등숙초기에는 65% 정도로 거의 일정하였으나 25일 이후는 일당 평균 1.8%씩 직선적으로 감소하였는데, 콤바인 수확작업이 가능한 시기는 백동은 출수후 40일, 올밀은 44일경으로 이때의 수분함량은 28%정도이었다. 5. 미탈부비율은 조기수확할수록 높았는데 이 비율이 5%이하로 되는 실용적 수확한계기는 백동은 출수후 40일 올밀은 45일경이었다. 6. 상맥립(2.8mm이상)을 얻을 수 있는 시기는 백동은 출수후 35일경, 올밀은 40일경이였으며, 단백질함량과 식미를 고려한 수확적기는 백동은 출수후 30~40일경, 올밀은 35~45일이었다. 7. 수량이 최대에 달하는 수확시기는 백동은 출수후 35일(745kg/10a), 올밀은 40일 (838kg/10a)이었고, 이보다 1일 앞당겨 수확함에 따라 수량은 3.9%와 4.4%씩 각각 감수되었다. 8. 이상을 종합하면 백동은 출수후 35일, 올밀은 40일경이 수량과 품질요인면에서 본 안전 조기 수확한계기로 여겨지며 콤바인 이용시는 이보다 5일정도 늦게 수확하는 것이 적합하였다