• Advances in nano research
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• v.12 no.6
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• pp.567-581
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• 2022

The free and forced vibration in addition to electric energy harvesting of a piezoelectric disk resting on two-parameter foundation modeled by modified couple stress as well as Kirchhoff plate theory is probed. The governing equations and boundary conditions are obtained using Hamilton's principle. Then, the free and forced vibration are solved using numerical solutions, generalized differential quadrature method (GDQM) and Newmark-beta method. The forced vibration is resulted from a base excitation load. Also, the possible voltage which can be harvested from this system is obtained using generalized integral quadrature method. The validity of the formulation and solution procedure is confirmed using a compassion study. The impact of parameters such as length effect, inner to outer radius ratio, and foundations parameters on the free and forced vibration as well as energy harvesting is investigated in detail. This paper can be a basis for future studies in the area of piezoelectric harvesters in small scales.

• Advances in nano research
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• v.14 no.1
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• pp.27-43
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• 2023

This article investigates the energy harvesting characteristics of a magneto-electro-elastic (MEE) cantilever beam reinforced with carbon nanotubes (CNT) under transverse vibration. To this end, the well-known lumped parameter model is used to represent the coupled multiphysics problem mathematically. The proposed system consists of the MEE-CNT layer on top and an inactive substrate layer at the bottom. The substrate is considered to be made of either an isotropic or composite material. Basic laws such as Gauss's Law, Newton's Law and Faraday's Law are used to arrive at the governing equations. Surface electrodes across the beam are used to harvest the electric potential produced, together with a wound coil, for the generated magnetic potential. The influence of various distributions of the CNT and its volume fraction, substrate material, length-to-thickness ratio, and thickness ratio of substrate to MEE layer on the energy harvesting behaviour is thoroughly discussed. Further, the effect of external resistances and changes in substrate material on the response is analysed and reported. The article aims to explore smart material-based energy harvesting systems, focusing on their behaviour when reinforced with carbon nanotubes. The results of this study may lead to an improved understanding of the design and analysis of CNT-based smart structures.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.2
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• pp.115-122
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• 2004

This study was conducted to investigate the effect of the seeding and harvesting dates on the growth characteristics, dry matter yield and quality of com for silage in alpine area(altitude 800m a.s.l.) of National Livestock Research Institute from 2001 to 2002. The experiment was arranged in a split plot design with three replications. Main plots consisted of three seeding dates, 10 May, 20 May and 30 May. Sub plots consisted of harvesting dates, 15 September, 25 September and 5 October. Tassel height of com was decreased with seeding dates, 30 May, 10 May and 20 May in order, and harvesting date of 5 October was apt to be high. Ear height of com was decreased with seeding dates, 20 May, 30 May, and 10 May in order, and harvesting date of 15 September was the lowest of all treatments. Ear rate of com was decreased with late seeding dates, and it was the highest with harvesting date of 5 October. Dry matter yield was decreased with late seeding dates(P<0.05), and it was increased with late harvesting regardless of seeding dates(P<0.05). Crude protein content of com stover was increased with late seeding dates, and that of com ear was the highest with seeding date of 20 May. And crude protein contents of com stover and ear were the highest with harvesting date of 15 September. NDF contents of com stover and ear were the highest with seeding date of 10 May and 20 May, respectively, and NDF content of com stover was the highest with seeding date of 10 May and there was no difference among treatments in NDF content of ear. ADF content of com stover was 42.1 to 42.6% regardless of seeding dates, and that of com ear was the highest with seeding date of 30 May. ADF content of com stover and ear was increased with early harvesting date excepting for harvesting date of 20 May. These results indicate that 20 May and 25 September would be the optimum seeding date and harvesting date, respectively, for dry matter yield and nutritive value of silage com in alpine area.

• Journal of Biosystems Engineering
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• v.5 no.1
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• pp.51-57
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• 1980

It is desirable to increase the diameter of rice bundle harvested by Japanese reaper binder recently introduced into Korean farmers , since it is too small for stalking in the field for preliminary drying prior to threshing operation which is dominant procedure in rice harvesting . Accordingly, this study was conducted to analyze the effect of the size of rice-bundle on the performance of binder and self-feeding thresher. The results are summarized as follows : 1. The diameter of rice-bundle could be increased from $\phi$80-98 to $\phi$105.0-125.4 while the number of rice bundles per 10 a were reduced to 1200 from 1600. The time required for harvesting 10 a of rice was 81 minutes in small size bundles and 84 minutes in large size bundles and no statistical difference was obtained. 2 .The grain loss due to discharge and cutting were slightly increased with large size bundle compared to the small size but no statistical difference was obtained. The precision of operation and drying rate was not significantly different between small and large size bundles. 3. The unthreshed losses were the same between large and small sizes of rice bundles when self-feeding thresher was used. When 8 PS engine was used , continuous operation was possible for small size bundles , but 1.5seconds of time interval was necessary for large size buldles. 4. The consumption of binding twine was reduced to 603 from 820 meters with the larger bundles , and the labour requirement for stalking rice bundles in the field was also reduced to 1.83 form 2.50 man-hour per 10 a Therefore, harvesting cost can be reduced up to 26.5 percent by increasing the bundle size.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.87-96
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• 2011

According to adverse effects of ecosystems due to a bulk of fossil fuel consumption, utilization of sustainable and renewable energy is required. In this paper, converting the energy crisis into an opportunity of new growth is expected by converting heat energy in asphalt pavement into electric power using thermoelectric effect. For this, experiments of inserting heat collector pipe and thermoelectric element into asphalt were performed, and the electric power of heat energy harvesting was measured for development of efficient harvesting system of heat energy. As the results of experiments, electric conversion of average 19.86W per day is possible at $1m^2$ conversion area at a depth of 5cm, and possibility of this system was confirmed. Consequently, a systematic "Green Road" using sustainable heat energy source in asphalt pavement simultaneously with environmental maintenance and econovic growth was suggested.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.73-84
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• 2015

Electricity generation using fossil fuels has caused environmental pollution. To solve this problem, research on new renewable energy sources (solar, wind power, geothermal heat, etc.) to replace fossil fuels is ongoing. These devices are able to generate power consistently. However, they have many weaknesses, such as high installation costs and limits to possible setup environments. Therefore, an active study on piezoelectric harvesting technology that is able to surmount the limitations of existing energy technologies is underway. Piezoelectric harvesting technology uses the piezoelectric effect, which occurs in crystals that generate voltage when stress is applied. Therefore, it has advantages, such as a wider installation base and lower technological costs. In this study, a piezoelectric harvesting device imitating seaweed, which has a consistent motion caused by fluid, is used. Thus, it can regenerate electricity at sea or on a bridge pillar, which has a constant turbulent flow. The components of the device include circuitry, springs, an electric generator, and balancing and buoyancy elements. Additionally, multiphysics analysis coupled with fluid, structure, and piezoelectric elements is conducted using COMSOL Multiphysics to evaluate performance. Through this program, displacement and electric power were analyzed, and the actual performance was confirmed by the experiment.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.187-190
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• 2005

This study was conducted to investigate the plant growth and seed yield between rain-shelter plastic house and out-door cultivation, and analysed the effect of harvesting time on seed quality. In rain-shelter plastic house cultivation, emergence date was 3 days and flowering date was 8 days earlier than out-door cultivation. Seed yield of rain-shelter plastic house cultivation was increased $25\%$ compared to out-door cultivation and it's more beneficial than out door cultivation. The crude fat content was higher and seed was whiter and better quality in rain-shelter plastic house cultivation than out-door cultivation. In out-door cultivation, the crude fat content was steadily increased until 40 days after full bloom, but the seed color was getting dark which was harvested at 30 days after full bloom and the color was turn to the dark brown when the seed was harvested at 40 days after full bloom. Harvesting of safflower seed's quality is best between 20 days and 30 days after full bloom.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.64-67
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• 1980

Field experiments were conducted to determine the optimum harvesting time and to evaluate the effect of Diquat spray in late seeded sesame, cultivar 'Suweon 9'. Sesame seed yield reached a plateau from Sept. 18 harvest when seed number was maximum. Thousand seed wt. increased to Sept. 29 harvest. As harvesting was delayed moisture content of capsule decreased and capsule dehiscence increased. Capsule dehiscence did not start until its moisture content dropped below 70%. Optimum harvesting might begin from the time which moisture content of capsule dropped below 70%, leaf senescence reached upper node, and 50% of capsules lost green. About 5% increase in seed weight after defoliation was estimated to be translocation from capsule wall. Diquat spray with 0.3% and 0.5% (v/v) solution of commercial Reglone (20%in A.I.) decreased rapidly capsule moisture content and promoted seed shattering. Dehiscence in 90% capsules was noted at seven days after Diquat spray. Diquat spray as a harvest aid could accelerate sesame desiccation up to 2 wks from normal field condition.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.159-166
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• 2011

Green house gas emissions are increasing as development of the industrial economy of the international community. Many countries in the world are endeavoring to reduce green house gas emissions under severe climate change. In order to protect grobal warming, government is trying to reduce green gas emissions under "Low Carbon Green Growth Policy" and investing climiate-firendly industries such as renewable energy harvesting. Renewable energy has been rapidly developing as a result of investment for development technology of using natural energy such as solar, wind, tidal, etc. There are lots of waste energy in the road space. However, nobody is not interested in waste energy from the road space. This paper present a fundamentally experimental study of energy harvesting technique to use waste energy in the road. The waste energy in the road is covered a pressure and impact of vehicles on the road, the radiant heat from asphalt pavement, road noise and vibration etc. In this study, an energy harvesting device using piezoelectric element is proposed and various tests are conducted to investigate a characteristic of this device as function of impact loading based on piezoelectric effect behavior. This paper shows the energy harvesting results of the device using domestic piezoelectirc element as a function of impact load size and pavement types.

• Journal of Korean Society of Forest Science
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• v.111 no.4
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• pp.644-650
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• 2022

Aralia elata (Miq.) SEEM is a deciduous shrub that has attracted attention as a high-income forest product. To improve the efficiency of cultivation and increase income, productivity according to the pruning period and annual pruning after harvesting Aralia elata shoots was analyzed. The optimal time was determined by pruning five times at 2-week intervals from 6 days after shoot harvesting. To investigate the pruning effect, pruning was performed at 30 cm from the ground in the first year after planting. From the second year after planting, branches grown for 1 year were pruned to 10 cm, and the annual shoots and branches were compared. Thenumber of first pruned branches after 6 days was 1.3-2.1 times higher after shoot harvesting than at other times, and the shoot characteristics were 1.2-1.7 times better than those at other periods. The faster the pruning, the better the quality of the harvested shoots. Annual pruning produced high-quality shoots (approximately 1.5 cm in diameter and 16 cm in length) from the second year after planting, and it was possible to increase productivity by inducing generation of branches capable of harvesting shoots. Annual pruning also made it possible to maintain easy shoot harvesting at approximately150 cm. These results showed that it was efficient to perform Aralia elatapruning as early as approximately 6 days after shoot harvesting. Pruning enabled production ofuniform-quality shoots every year and increasedthe yield of the trees.