• Journal of Forest and Environmental Science
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• v.29 no.1
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• pp.81-89
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• 2013

Nowadays, excessive using of fossil fuel contributes to global warming. Also, this phenomenon increases steadily. Therefore forest biomass from logging residues has received attention. The goal of this study was to determine the sustainability and economic feasibility of forest-biomass energy source. Accordingly, forest biomass resource was calculated, and harvesting and transporting machines which can be used in investing area were chosen, when using forest biomass as energy source. And then through these data, the harvesting cost was decided. The forest biomass resource calculated, thinned trees and logging residues, was 37,330.23 $m^3$ and 14,073.60 ton, respectively. When harvesting timber in each sub-compartment, the average thinned trees yield was 120.73 $m^3$, and tree logging residues was 402.80 ton. The use of tower yarder as harvesting and transporting equipments in study area was 85.4% and 66.7%, respectively, in up hill and down hill yarding. The average harvesting cost of biomass in the possibility area of timber yarding operation was expensive as 81,757 won/$m^3$, 85,434 won/m3 and 50,003 won/ton, respectively, in thinned trees and logging residue. If using data from this research analysis, tree could be felled by choosing sub-compartment.

• Journal of Forest and Environmental Science
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• v.24 no.1
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• pp.1-14
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• 2008

Clearcutting has been the dominant harvesting method in British Columbia (representing 95% of the total area harvested annually). However forest managers are increasingly recommending the use of alternative silvicultural systems and harvest methods, including various types of partial cutting, to meet ecological and social objectives. In this study we compared harvesting productivity and harvesting costs between treatments through detailed and shift level time studies in 300-350 year-old Interior Cedar-Hemlock stands in British Columbia, Canada. Recommendations for improving operational planning/layout and the implementation of clearcut and partial cutting silvicultural systems were made. Harvesting costs varied in the ground-based clearcut treatments from $10.95/$m^3$ - $15.96/$m^3$ and $16.09/$m^3$ - $16.93/$m^3$ in the group selection treatments. The ground-based group retention treatment had a cost of $13.39/$m^3$, while the cable clearcut had a cost of $15.70/$m^3$. An understanding of the traditional and alternative wood products that could be derived from the harvested timber was imperative to increasing the amount of merchantable volume and reducing the corresponding harvesting costs. Stand damage was greatest in the group selection treatments; however, mechanized felling showed an increase in stand damage over manual felling while grapple skidding showed a decrease in skidding damage compared to line skidding.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3735-3740
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• 2012

In this paper, the performance of power generation for the energy harvesting block with a combination of piezoelectric technology and electromagnetic technology among various energy harvesting technologies was investigated. The goal of this study is to evaluate on the applicability of our developed energy harvesting block into the field of urban & housing. First, we carried out a finite element vibration analysis and evaluated the performance of power generation for the multi-layer energy harvester at laboratory scale. Second, we described the features of our developed prototype module that includes amplification technologies to improve power density per module and evaluated the performance of power generation for the energy harvesting block in a variety of ways. Finally, we suggested the direction for the improvement of the energy harvesting block module.

• Food Science and Preservation
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• v.30 no.5
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• pp.811-821
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• 2023

This study investigated the storability of onions according to manual and mechanical harvesting. Moreover, we simulated the onion-to-onion impact during the mechanical harvesting process and investigated the storability after artificially subjecting the onions to impact treatment. The onion harvesting methods included hand plucking + manual collection, digger + manual, and digger + mechanical collection. The maximum impact height during the mechanical harvesting process was 0.5 m. Immediately after harvesting, no significant difference in the bruise and wound rate among the harvesting methods was observed. Any increased bruise or wound rate because of mechanical harvesting was presumed to be influenced by soil conditions, such as the presence of gravel, and machine operation factors. Furthermore, the storability during the 8.5 months storage showed no significant difference according to the harvesting methods. In treatments by simulating the impacts during the mechanical harvesting process, the impact heights were 0.0 m (0.0 J), 0.25 m (0.86 J), 0.5 m (1.72 J), and 0.75 m (2.57 J), each performed once, and four times at the same position (3.43 J) and four times at different positions (3.43 J) at 0.25 m. Throughout all the treatments, there were no significant differences in the storability during the 8.5 months storage period.

• Bulletin of the Korean Mathematical Society
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• v.52 no.4
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• pp.1069-1076
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• 2015

In this paper, a two species competitive model with stage structure and harvesting is investigated. By using the differential inequality theory, some new sufficient conditions which ensure the permanence of the system are established. Our result supplements the main results of Song and Chen [Global asymptotic stability of a two species competitive system with stage structure and harvesting, Commun. Nonlinear Sci. Numer. Simul. 19 (2001), 81-87].

• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.387-401
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• 2006

This paper deals with the problem of a ratio-dependent prey- predator model with combined harvesting. The existence of steady states and their stability are studied using eigenvalue analysis. Boundedness of the exploited system is examined. We derive conditions for persistence and global stability of the system. The possibility of existence of bionomic equilibria has been considered. The problem of optimal harvest policy is then solved by using Pontryagin's maximal principle.

• Bulletin of the Korean Chemical Society
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• v.25 no.3
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• pp.343-344
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• 2004

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.385-395
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• 2007

The dynamics of a prey-predator system, where predator population has two stages, juvenile and adult with harvesting are modelled by a system of delay differential equation. Our analysis shows that, both the delay and harvesting effort may play a significant role on the stability of the system. Numerical simulations are given to illustrate the results.

• Korean Journal of Medicinal Crop Science
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• v.5 no.3
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• pp.232-236
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• 1997

This experiment was conducted to determinate the optimum harvesting time of Carthami Flos and grain in safflower. In dry Carthami Flos yields harvested at different days after flowering, threre was no significant difference between 2 days and 4 days, however, yield harvested at 6 days was decreased significantly compared with 2 days after flowering. As the harvesting time were delayed, lightness (L') and redness (a') of dry Carthami Flos were decreased but yellowness (b') of that was increased. Color differences (${\Delta}E'ab$) of dry Carthami Flos between harvesting days after flowering were not visible between 4 days and 6 days but between those (4 days and 6 days) and 2 days were visible. As the result, the optimum harvesting time of Carthami Flos was 4 days after flowering. Grain yields and its components were affected by not harvesting Carthami Flos but grain harvesting time. Threre was no significant difference in number of grain per flower head, percentage of ripened grain between grain harvesting time. However, weight of 1000 grains and grain yields increased until 20 days after flowering. As a conclusion, the optimum harvesting time was 4 days after flowering for Carthami Flos and 20 days for grain regardless Carthami Flos harvesting time.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.172-178
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• 2006

The dynamics of bacterial populations belonging to $\alpha\;\beta\;\gamma-subclass$ proteobacteria, Cytophaga-Flavobacterium (CF) group and sulfate reducing bacteria (SRB) in water column of the middle reaches of Nakdong River depending on sediment harvesting were analyzed by fluorescent in situ hybridization (FISH) at sediment harvesting site (near the Seongju bridge) and non-sediment harvesting site (near the Gumi bridge). In addition, some physico-chemical parameters such as temperature, pH, $chi-\alpha$ and electrical conductivity were measured. Regarding the number of total cell counts, cells stained by DAPI, there were no substantial quantitative differences between both sites, but those fluctuation at sediment Harvesting site was greater. And also the ratios of CFgroup and SRB to total cell counts tend to increase at sediment harvesting site with higher $chl-\alpha$, maybe due to the resuspension of sediment into water column. But the total proportion of all determined bacterial populations to total cell counts were greater at non-sediment harvesting site, compared with those at sediment harvesting site. Since the detectibility of bacteria by FISH depends on their metabolic activity, those lower proportion at the sediment harvesting site implies that sediment harvesting may lead to malfunction of those bacteria respect to nutrient recycling and subsequently negative effects on microbial food web.