• Journal of Forest and Environmental Science
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• v.38 no.4
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• pp.256-262
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• 2022

The timing of seed harvesting is an important decision in the management of seed orchards because it affects seed quality and yield. To investigate the effect of cone harvest time on seed quality and determine the optimal harvesting time, cones were regularly collected in seven times and germination tests were performed at each harvest time in two clonal seed orchards of Chamaecyparis obtusa. As cones developed, the percentage of seed germination increased before cone moisture content began to decrease significantly. The moisture contents of cones were highest at the first collection as 68.3% and 67.3% in Jeju and Gochang seed orchards respectively. At this time, germination speed was slowest, indicating poor seed vigour. The highest germination was found at the second stage in Jeju (36.5%) and at the seventh stage in Gochang (28.6%) seed orchard. The germination speed increased as cone moisture content decreased. Additionally, changes of seed vigour differed among the developmental stages in both seed orchards. Consequently, the optimal cone harvest time of C. obtusa seed orchards in Jeju was early September when high germination percentage was obtained. In Gochang seed orchards, late October was optimal cone harvest time when the germination speed was fast and the cone moisture content decreased.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.10
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• pp.1540-1546
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• 2017

In piezoelectric device applications, it is important to improve a system efficiency because of the low generated power. In this paper, an optimal driving method is proposed to improve a system efficiency for a piezoelectric energy harvesting system. The proposed method considers disappear energy in input capacitors and the converter efficiency according to the input voltage magnitude to minimize energy losses. Experimental results based on various energy generation cases verify that the proposed method significantly improves the system efficiency; the efficiency is approximately 9.97% higher than that of the conventional method.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.300-300
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• 2017

'Saemimyeon' a Tongil-type rice variety (Indica ${\times}$ Japonica), which contains high amylose contents is suitable for rice noodle production. Nowadays, the major parts of rice processing industry that includes products like rice flour and noodles are expected to partially replace wheat flour market. The volume of rice noodle market is getting bigger and can contribute to the rice surplus and farmer's income. This study was carried out to promote productivity and flour-making quality of 'Saemimyeon' by finding the most suitable transplanting and harvesting times. The transplanting days used were May $10^{th}$, May $17^{th}$, May $24^{th}$, May $31^{th}$, June $7^{th}$ and June $14^{th}$ and the planting distance used was 30 x 12cm. In addition, harvesting time was determined by days after heading time (40, 45, 50, 55 and 60 days). The field experiment was conducted at the experimental field in Miryang (Southern plain area of Korea) from 2015 to 2016. Our results suggest that the optimum transplanting days were from May $24^{th}$ to May $31^{th}$ which resulted to an average yield of 748~751kg/10a. Interestingly, yield was sharply decreased below 700kg/10a before May $10^{th}$ and after June $7^{th}$. The average grain filling rate before May $31^{th}$ was more than 83% but it declined to 75% after June $7^{th}$. The average temperature ranges from heading time to harvesting time was $ 21\sim25^{\circ}C$ and the estimated optimal temperature was $23.4^{\circ}C$ which is similar to May $24^{th}$ by regression equation. We found that the optimal harvest time was 45~50 days after heading time. It is hypothesized that low temperature at seed maturation time caused the lower grain filling rate therefore 'Saemimyeon' need to be transplanted before May $31^{th}$ for higher productivity. We found no statistical variation in amylose contents among experimental plots (28.2~30.4%). We conclude that the productivity of 'Saemimyeon' highly depends on temperature that is critical for grain filling stage controlled by transplanting time.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.2
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• pp.174-179
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• 2015

This experiment was conducted to determine the optimal harvesting time for barley and wheat grain for the production of fermented grain feeds, and to investigate their fermentation quality according to harvesting time. As a result, grain moisture content was decreased with late harvest, whereas spike weight ratio and 1000 grain weight were increased with prolonged period after heading. Grain yielding was increased with late harvesting time significantly at p<0.05. Crude protein content was increased with late harvesting time, but crude fiber content was decreased. Crude fat and ash content were slightly decreased, but not statistically significant. Comparing the effects of fermentation on feed value of winter cereal grain, the approximate compositions were slightly increased after fermentation, but the difference was not significant. Fermentations resulted in increasing the pH value of winter cereal grain silage with late harvesting time, but decreasing the lactic acid content (p<0.05). No significant difference was found in acetic acid, and butyric acid was not detected. Considering the quantity and quality of fermentation, barley and wheat can be used for winter cereal grain silage when they were harvested at 35 days and 40-45 days after heading, respectively.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.3
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• pp.215-218
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• 2012

We have carried out the experiment to investigate optimal drainage time of barley seeding synchronized with rice harvesting in paddy field. Number of emerged barley seedling on moist paddy field was less than that of common paddy field. It is very hard to plow using combine owing to long time to work on wet condition compared to drying condition of paddy field. According to the drainage time, growth and yield of barley were not significantly different. However, late drainage time decreased the spikes per $m^2$. Rice yield and 1,000 husked rice grain weight were not significant depending on drainage times at 15 days, 20 days and 25 days before barley seeding. The range of 1,000 husked rice grain weight was 21.7~22.2 g on different drainage conditions. In results, on considering of soil hardness and time of labor, the optimal contents of soil moisture was about 33%. This study reveals that drainage time at 20 days before barley seeding is proper to increase seedlings and yield.

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.299-310
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• 1994

This study was carried out to examine the optimal road spacing and road density to minimize the total harvesting cost(road construction cost plus yarding cost) for mechanized yarding system to roadside by one - and two-stage two-way in Forestry build-up region. Chunchon-kun, Kangwon-do. The estimated road construction costs were ranged from ten million won to sixty million won per km. The results have indicated that cable crane was appropriate for yarding machine by one-stage, two-way, and estimated optimal road spacing was 1,698m~4,192m, averaged 3,087m, and road density was 3.44m/ha~8.44m/ha, and averaged 5. 12m/ha. In hilly terrain, combination of medium yarder and Logging bogie was suited to yarding machine by two-stage, two-way, and calculated optimal road spacing was 1,483m~3,481m, averaged 2,589m, and road density was 4.05m/ha~9.46m/ha, averaged 5.90m/ha. In steep terrain, combination of medium yarder and jinsung winch was suited, and estimated optimal road spacing was 1,693m~3,982m, averaged 2,960m, and road density was 3.68m/ha~8.64m/ha, averaged 5.38m/ha.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.429.1-429.1
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• 2002

In the patients with hematologic and solid tumors. clinical application of peripheral blood stem cells (PBSCs) increases to reconstitute hematopoiesis after high-dose chemotherapy. To mobilize PBSCs. the hematopietic growth factors have been widely used as single treatment or after chemotherapy. The important issue in the collection of PBSCs is to predict their potential capability to reconstitute hematopoiesis. which depends on optimal time of leukapheresis and the quantity of collected PBSCs. (omitted)

• KSBB Journal
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• v.29 no.3
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• pp.220-224
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• 2014

Flocculation is known one of the effective methods for harvesting microalgae. This study was aimed to optimize the flocculation condition for decreasing the amounts of flocculant and obtaining the highest yield of algal biomass. To achieve this goal, it was optimized the flocculant concentration, reaction pH and the concentration of cell density for harvest using response surface methodology (RSM). The flocculation of microalgae, Spirogyra varians, was carried out using inorganic flocculant polyaluminium chloride. By the RSM result, the optimal flocculation condition was calculated 5 ppm of polyaluminum chloride, pH 7.5 and 0.33 of optical cell density at $OD_{640}$. The obtained recovery yield of S. varians was 97.6% at the optimal condition.

• Journal of applied mathematics & informatics
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• v.27 no.5_6
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• pp.1411-1427
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• 2009

We propose a model based on Lotka-Volterra dynamics with two competing spices which are affected not only by harvesting but also by the presence of a predator, the third species. Hyperbolic and linear response functions are considered. We derive the conditions for global stability of the system using Lyapunov function. The optimal harvest policy is studied and the solution is derived in the interior equilibrium case using Pontryagin's maximal principle. Finally, some numerical examples are discussed. The nature of variations in the two prey species and one predator species is studied extensively through graphical illustrations.