• Food Science and Preservation
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• v.13 no.5
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• pp.538-542
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• 2006

Physicochemical properties and positional distribution of Hallabong Tangor (Citrus Kiyomi ${\times}$ ponkan) cultivated in heated greenhouse were investigated. About 90% of Hallabong produce fruit within the range of $250{\sim}400g$ fruit weight on a tree, larger fruits were mainly consisted of $400{\sim}450g$ in M16A, a variant species of Hallabong, due to younger tree and fruit thinning. Nevertheless fruit sizes of M16A were larger than Hallabong, and peel thickness of M16A (3.29 mm) was thinner than that of Hallabong (3.51 mm). Hardness of m6h was 994.69g-force, compared to 832.8 g-force of Hallabong on the average. Soluble solids and acid content of Hallabong were $12.20{\sim}12.98^{\circ}Brix$ and $1.08{\sim}1.14%$, while those of M16A were $1.48{\sim}12.63^{\circ}Brix$ and $0.92{\sim}1.00%$, respectively. Vitamin C content of Hallabong was $71.30{\sim}78.77 mg/100 g$, compared to $64.40{\sim}68.01mg/100g$ in M16A. Soluble solid in the part of stem was lower than that of end part among the same segment. Fruit size in the upper part of the tree was larger, the peel was thicket and flesh ratio was lower than the middle or lower part. However, soluble solids and acid content were high, due to cumulative sunshine during cultivation.

• Korean Journal of Agricultural Science
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• v.49 no.3
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• pp.421-430
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• 2022

Crop load management in apple trees is important for achieving optimum productivity and crop value. Hence, we investigated the influence of different crop loads on the fruit quality, mineral content, and yield of the 'RubyS' apple variety. After 4 weeks of full bloom, the crop load was adjusted by hand thinning to different (5, 10, and 15 fruits·cm^-2) trunk cross-sectional areas (TCSA), representing low, medium, and high crop loads. The low crop load increased the fruit size and weight, the development of the red-blushed area, and the peel color a^* at harvest; however, it reduced the total number of fruits·tree^-1 and yield compared with that of the other crop loads. The medium crop load improved the fruit weight, flesh firmness, and soluble solids content and reduced the fruits·tree^-1 but did not affect the fruit size and yield. However, there were no significant differences in the titratable acidity and starch index among the crop loads. The fruit mineral content (phosphorus and potassium) was higher in the low and medium crop loads compared to the high crop load. However, the nitrogen, calcium, and magnesium contents in the fruits were not affected by the crop loads. Overall, this study suggests that a low crop load improves the fruit size and weight, but its effect on the quality and fruit mineral content is similar to that of a medium crop load. Therefore, the optimum crop load level for the 'RubyS' apple trees was approximately 10 fruits·cm^-2 TCSA.

• Journal of Korean Society of Forest Science
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• v.108 no.4
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• pp.574-581
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• 2019

The present study analyzed the productivity and cost of winching operations for evaluating the efficiency of a tractor-attached winch in a Pinus densiflora thinning site located in the Yangyang County of Gangwon-do. The mean yarding distance and mean timber volume were 29 m and 0.15 ㎥, respectively. In the 95 cycles of yarding operations, the uphill and downhill yarding operations constituted 51% and 49%, respectively, of the total yarding operations. The productivity of the uphill yarding operation was 2.28 ㎥/h, and the productivity of the downhill yarding operation was 1.89 ㎥/h. The findings of this study revealedthat productivity would increase by 0.5 ㎥/h when the rate of utilization of the machine is increased to 80% by reducing the operational delay time. The cost of the downhill yarding operation was 44,116 KRW/㎥, whereas that of the uphill yarding operation was 53,369 KRW/㎥. The difference in cost resulted from the difference in the number of yarding stems (stems/cycle). Furthermore, the results of the multiple linear regression equation developed for predicting the yarding operation times showed that productivity was significantly affected by working conditions such as yarding distance (m), the number of stems per cycle (stems/cycle), and the terrain slope (%) in the uphill and downhill yarding operations. Further research is required for developing an accurate prediction model equation according to a yarding direction.

• Journal of Korean Society of Forest Science
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• v.95 no.6
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• pp.729-734
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• 2006

This paper aimed to suggest decision-making method for forest management planning using integer programming. Thus, the study examined 85 stands consisting of Korean pine, Japanese larch and oak stands-all of which were at the most suitable time for tending, selection thinning, commercial thinning and final cutting-in the experimental forest of Kangwon National University. The forest management model comprised one objective function, maximizing harvest volume in each stand according to tree species and the kinds of practices, and seven constraints: frequency and stands of practices, minimum and maximum yields, even yields, maximum production, and decision-making varialbes. Besides, the entire period intended by the study was 10 years, divided into 5 management periods. In conclusion, the forest management planning model using integer programming proved that among 85 stands, forest practices were conducted over 68 stands (202.8 ha), producing the total harveted volume of $20,000m^3$, while the rest was reserved. This case study could help make decisions on whether and when the forest practices and harvests could be done in a specific condition.

• Journal of Korea Water Resources Association
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• v.55 no.12
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• pp.1065-1076
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• 2022

The purpose of this study was to investigate the effect of the expansion and withering of Salix subfragilis communities on the water quality in Namgang Dam reservoir. The distribution area of the Salix subfragilis communities was 0.12 km² in 2003 for the first time, but it was 3.58 km² in 2019, which has increased rapidly by about 30 times in 16 years. However, in 2013, the distribution area has decreased by 0.17 km² due to long-term immersion in high turbidity, and self-thinning in Salix subfragilis communities. The lake characteristics of reservoir showed a combination of lake type and river type in terms of average water depth, watershed area/lake surface area ratio, water residence time, flushing rate, and stratification. From the result of analyzing long-term changes in lake water quality, COD, TP, and chlorophyll-a in Salix subfragilis communities were significantly larger than those in the three points located in the central part of reservoir. In particular, the fact that the value of chlorophyll-a showed the maximum value in winter rather than summer, unlike the trend of the three points in the Namgang Dam water quality monitoring network, is thought to have occurred internally rather than externally. It can be estimated that one cause of this deterioration of the water quality in Namgang Dam reservoir is the huge amount of nutrients generated in the decomposition process of by-products such as fallen leaves, branches and withered trees in Salix subfragilis communities.

• Korean Journal of Environmental Agriculture
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• v.42 no.3
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• pp.239-252
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• 2023

Most apple trees in South Korea are grafted on M.9 and M.26 rootstocks; however, these rootstocks are susceptible to fire blight. Although M.7 rootstocks are moderately resistant to fire blight, they tend to exhibit excessive vigor, which is unsuitable for high-density planting, unless weak cultivars are used. This study investigated the vegetative growth, yield, and fruit quality of apple trees grafted onto M.7, M.9, or M.26 rootstocks to assess the feasibility of establishing high-density apple orchards domestically using the M.7 rootstock a period of seven years (1-7 years after planting). Rootstocks were tested using three cultivars with contrasting induced vigor and harvesting times: vigorous and late-maturing 'Fuji,' moderate vigor and middle-maturing 'Hongro,' and low vigor and early-maturing 'Sansa.' The planting density was maintained constant, with 190 trees per 10 a. Primary thinning (leaving only the king fruit on clusters) was performed, whereas secondary thinning (controlling crop load) was not. Vegetative growth, accumulated yield per 10 a, and yield efficiency varied depending on cultivars and rootstocks; however, the cultivars had a more notable effect on fruit quality than the rootstocks. Biennial bearing often occurred in the M.26 rootstock. 'Fuji'/M.7 was overly vigorous for high-density planting. The fruit quality and accumulated yield per 10 a of M.7 were similar to those of M.9 with the 'Hongro' and 'Sansa' cultivars. In particular, 'Hongro'/M.7 did not show tree vigor reduction due to heavy crop load, and the degree of biennial bearing in 'Sansa'/M.7 was not particularly high. These results indicated that high-density apple planting using the M.7 rootstock was achievable using the 'Hongro' and 'Sansa' cultivars.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.1
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• pp.1-19
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• 2022

The Geumgang Pine (Pinus densiflora) Forest in Sogwang-ri, Uljin has traditionally been a pine tree protection area (prohibited forest) for timber production purposes, and is now designated and managed as a protected area for forest genetic resource conservation by the Korea Forest Service. This study, we analyzed topographical characteristics, existing vegetation, tree age, and plant community structure, and proposed a sustainable management method for the Geumgang Pine (Pinus densiflora) Forest in Sogwang-ri, Uljin for timber havesting purposes. The topographical characteristics of the target area were 36.7% ridges and 38.7% valleys; the ratio of ridges to valleys was similar, and the slopes formed 24.7% of the total area. The types of pine forest communities are divided into six types based on the progress of pine forest renewal, the competition with other species such as deciduous broadleaf trees, and the formation of layered structures. It has been confirmed that the age of the large-diameter pine trees (40~60cm in diameter) is approximately 60~70 years, which is relatively low. As a result of the analysis of the relative importance percentage and layered structure, differences depended on the progress of the pine forest renewal project, and not only the maintenance of the pine forest, but also the creation of a secondary growth forest, the density adjustment of pine trees, and the active management of competitive trees. The average basal area by the community was 12,642.1~25,424.4cm² for the tree layer and 1.8~1,956.5cm² for the low tree layer based on a quadrat of 400m². The difference in the basal area appeared to depend on the size and number of trees forming the tree layer and the degree of pine forest renewal (the degree of time elapsed after thinning pine trees). The average number of species that appeared in each community was 8.7-20.3; there were many species located in valleys, and the type competes with deciduous broadleaf trees due to the lack of management. The diversity of species ranged from 0.6915-1.0942, and was evaluated as low compared to pine communities in central temperate zones. In this paper, we determined the management goals of Geumgang Pine (Pinus densiflora) Forest in Sogwang-ri, Uljin to produce timber with high economic value, and suggested efficient vegetation management for continuous afforestation, the establishment of a timber production system, and improvement of wood production as a management direction.

• Korean Journal of Plant Resources
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• v.21 no.1
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• pp.5-11
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• 2008

This study examined the characteristics of Pinus thunbergii community that forms a windbreak forest around the coast of Gwanmaedo located in Jodo-myeon, Jindo-gun, Jeollanamdo which is located in the south-western areas of Korea from December 2005 to April 2007 and to suggeste the ecological management methods of coastal windbreak areas. P. thunbergii community, a coastal windbreak forest of Gwanmaedo, was classified into disturbance, growth, mixture, stability, and back mountain vegetation according to major companions species and vegetation types. P. thunbergii community of disturbance and growth vegetation needs active management through tree thinning, mowing, weeding out, use of rest space, and felling sick pine trees. P. thunbergii community of mixture, stability, and back mountain vegetation needs active preservation of a coastal windbreak to restore natural vegetation by making a windbreak walk and a forest buffer zone and inducing vegetation succession. Accordingly, in this study, ecological management methods were suggested according to the actual state of distribution by habitat characteristics of coastal windbreak areas such as management of beaches and surrounding area of idle lands, restoration of back wetlands, inhibition of foreign plants, maintenance of diversity of species and habitats, and prevention of aging and spread of damage from insects.

• Journal of Korean Society of Forest Science
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• v.109 no.2
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• pp.202-210
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• 2020

This study investigated the optimal levels of stand density control considering the stability of Larix kaempferi stands. A stand density management diagram was developed from 259 sample plots. Based on these data, we determined an optimal level of the stand density control by identifying the relationship between the relative yield index (Ry) and height-to-diameter ratio. The estimated r-square (R²) of the stand density management diagram is 0.600. The analysis of the relationship between Ry and the slender tree incidence showed that when the stand density exceeded a certain threshold and the ratio of slender trees rapidly increased. The critical value of Ry was 0.63. The results of this study are expected to contribute to the establishment of stand management strategies that can reduce damage from natural causes, such as wind and snow, and to develop stand practice systems for the improved productivity of commercial forests.

• Journal of the Korea Furniture Society
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• v.25 no.4
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• pp.345-352
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• 2014

This study was carried out to develop eco-friendly wood street lamp (EFWSL) by using wood resources stacked in the forests after tree tending operations which were mostly abandoned, but economical as renewable wood resources for developing the wood coated street lamps with the effects of cost reduction and their attractive appearances. This study has led to the development of key compact structures of street-lighting wood poles (shaft) using laminated timber. The core technique in this study is related with producing the more stable wood poles (shaft) with the hole inside than wood poles exposed under the natural environment through applicable process to protect the wood from bursting and splitting. We also comprehensively developed the method to conserve the timber durability of wood shaft and connect the wood shaft with groove, race way to be located in the groove, locking ring, current stabilizer connected to the groove and luminaire support arm, base and hand-hole which was partly used in combination with steel materials and wood. Also we increased the utilization of abandoned and stacked woods after thinning in the forests such as Pinus densiflora, Larix leptolepis, and Pinus koraiensis plantations by maximizing the value of these natural wood resources as main materials of eco-friendly street lightings with the effects of cost reduction and attractive appearances and also the expectation of advertising effects of street lightings developed in this study.