• 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.

• 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 Medicinal Crop Science
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• v.26 no.6
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• pp.464-470
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• 2018

Background: Ginseng produced by hydroponics can be cultivated without using agricultural chemicals; thus, it can be used as a raw materials for functional foods, medicines, and cosmetics. This study aimed to determine the optimal harvesting time to obtain the highest levels of ginsenoside and ginseng, as this was not previously unknown. Methods and Results: One-year-old organic ginseng seedlings were transplanted and cultivated using hydroponics for 150 days in a venlo-type greenhouse, using ginseng nursery bed soil and a nutrient solution ($NO_3{^-}-N$; 6.165, P; 3.525, K; 5.625, Ca; 4.365, Mg; 5.085, S; $5.31mEq/{\ell}$). Ginsenoside content and fresh and dry weights were higher at 120 days after transplanting than at 30, 60, 90, and 150 days. Total ginsenoside content was 11.86 times higher in the leaf and stem than in the root at 120 days after transplanting. Ginsenosides F1, F2, F3, and F5 were detected in ginseng leaves and stems. These chemical compounds are known to be effective in altering skin properties, including whitening, anti-inflammation, and anti-aging. Conclusions: Optimal harvesting time for ginseng cultivated using hydroponics was 120 days after transplanting when the biomass and ginsenoside content were highest.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1679-1685
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• 2022

In this paper, we propose an optimal multi-hop transmission scheme to maximize the end-to-end data rate from the source to the destination node in a wireless powered communication network. The frame structure for multi-hop transmission is presented to transmit multi-hop data while harvesting energy. Then, the transmission time of each node that maximizes the end-to-end transmission rate is determined through mathematical analysis in consideration of different harvested energy and link quality among nodes. We derive an optimization problem through system modeling of the considered wireless powered multi-hop transmission, and prove that there is a global optimal solution by verifying the convexity of this optimization problem. This analysis facilitates to find the optimal solution of the considered optimization problem. The proposed optimal multi-hop transmission scheme maximizes the end-to-end rate by allocating the transmission time for each node that equalizes the transmission rates of all links.

• 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.

• The Journal of Korea Robotics Society
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• v.15 no.2
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• pp.100-106
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• 2020

In the agricultural field, interests in research using robots for fruit harvesting are continuously increasing. Dual arm manipulators are promising because of its abilities like task-distribution and role-sharing. To operate it efficiently, the task sequence must be planned adequately. In our previous study, a collision-free path planning method based on a genetic algorithm is proposed for dual arm manipulators doing tasks cooperatively. However, in order to simplify the complicated collision-check problem, the movement between tasks of two robots should be synchronized, and thus there is a problem that the robots must wait and resume their movement. In this paper, we propose a heuristic algorithm that can reduce the total time of the optimal solution obtained by using the previously proposed genetic algorithm. It iteratively desynchronizes the task sequence of two robots and reduces the waiting time. For evaluation, the proposed algorithm is applied to the same work as the previous study. As a result, we can obtain a faster solution having 22.57 s than that of the previous study having 24.081 s. It will be further studied to apply the proposed algorithm to the fruit harvesting.

• 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 the Korea Society of Computer and Information
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• v.29 no.1
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• pp.1-9
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• 2024

This paper proposes an integration of the ED-H scheduling algorithm, known for optimal real-time scheduling, with the LoRaEnergySim simulator. This integration facilitates the simulation of interactions between real-time scheduling algorithms for tasks with time constraints in Class-A LoRaWAN Class-A devices using a super-capacitor-based energy harvesting system. The time and energy characteristics of LoRaWAN status and state transitions are extracted in a log format, and the task model is structured to suit the time-slot-based ED-H scheduling algorithm. The algorithm is extended to perform tasks while satisfying time constraints based on CPU executions. To evaluate the proposed approach, the ED-H scheduling algorithm is executed on a set of tasks with varying time and energy characteristics and CPU occupancy rates ranging from 10% to 90%, under the same conditions as the LoRaEnergySim simulation results for packet transmission and reception. The experimental results confirmed the applicability of co-simulation by demonstrating that tasks are prioritized based on urgency without depleting the supercapacitor's energy to satisfy time constraints, depending on the scheduling algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.504-521
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• 2016

Recently, energy harvesting technology has been integrated into wireless sensor networks to ameliorate the nodes' energy limitation problem. In theory, the wireless sensor node equipped with an energy harvesting module can work permanently until hardware failures happen. However, due to the change of power supply, the traditional hierarchical network routing protocol can not be effectively adopted in energy harvesting wireless sensor networks. In this paper, we improve the Low-Energy Adaptive Clustering Hierarchy (LEACH) protocol to make it suitable for the energy harvesting wireless sensor networks. Specifically, the cluster heads are selected according to the estimation of nodes' harvested energy and consumed energy. Preference is given to the nodes with high harvested energy while taking the energy consumption rate into account. The utilization of harvested energy is mathematically formulated as a max-min optimization problem which maximizes the minimum energy conservation of each node. We have proved that maximizing the minimum energy conservation is an NP-hard problem theoretically. Thus, a polynomial time algorithm has been proposed to derive the near-optimal performance. Extensive simulation results show that our proposed routing scheme outperforms previous works in terms of energy conservation and balanced distribution.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4223-4239
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• 2016

In this paper, we consider an amplify-and-forward (AF) full-duplex relay network (FDRN) using simultaneous wireless information and power transfer, where a battery-free relay node harvests energy from the received radio frequency (RF) signals from a source node and uses the harvested energy to forward the source information to destination node. The time-switching relaying (TSR) protocol is studied, with the assumption that the channel state information (CSI) at the relay node is imperfect. We deliver a rigorous analysis of the outage probability of the proposed system. Based on the outage probability expressions, the optimal time switching factor are obtained via the numerical search method. The simulation and numerical results provide practical insights into the effect of various system parameters, such as the time switching factor, the noise power, the energy harvesting efficiency, and the channel estimation error on the performance of this network. It is also observed that for the imperfect CSI case, the proposed scheme still can provide acceptable outage performance given that the channel estimation error is bounded in a permissible interval.