• Journal of The Korean Society of Grassland and Forage Science
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• v.21 no.4
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• pp.225-232
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• 2001

In order to identify the optimum seeding rate of Jeju barnyard grass (Echinochloa crusgalli var. fiurnentacea(Roxb) Wight), 15, 20, 25, 30, 35 and 40 kilograms per a hectare were planted in April 16, 2000, respectively. The growth characterization, the yield and chemical composition were then investigated in June 28(1st cutting) and August 30(2nd cutting), 2000. According to increasing the seeding rate, plant height(155.5 to 162 cm), the yield of fresh forage(61 to 73 MT/ha), dry matter forage(11.9 to 16.9 MT/ha), crude protein(0.9 to 1.6 MT/ha), and TDN(6.1 to 9.7 MT/ha) were gradually increased until the seeding furrow, 35 kg/ha. In 40 kg/ha of seeding furrow, however, those results were decreased than that of the former seeding furrow. The contents of crude protein(7.4 to 10.4%), ether extract(3.3 to 5.2%), nitrogen free extract(46.4 to 47.8%), and TDN(52.1 to 60.4%) were also similar to those of the plant heights and the each yield excepted the seeding furrow, 40 kg/ha. Namely, the each results about the contents increased in 40kg/ha of seeding furrow. According to increasing the seeding rate, the stem diameter, number of leaves, number of withering leaves, and fresh weight were gradually decreased. The contents of crude fiber(30.3 to 27.5%) and crude ash(12.7 to 9.0%) were also decreased These results showed that the optimum seeding rate for the best of the feed production was the seeding furrow, 35 kg/ha.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.145-153
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• 1995

Effects of lime application levels(0, 10, 50, 100, and 300kg/10a) on three alfalfa cultivars(Dekalb brand 120, Pike, Pioneer brand 5929) were analyaed with respect to the growth, dry matter yield, and inorganic composition of the plants at three cutting periods. Major chemical properties of the soils were also analyzed. Response of the plant height to the lime application level was variable among the cultivars, showing the order of 50>100>300>10>0kg/10a in Dekalb brand 120, 50>100>10>300>0kg/10a in Pike, and 10>50>300>0>100kg/10a in Pioneer brand 5929. The order of dry matter yield response to the lime application level was 50>300>100>10>0kg/10a in Dekalb brand 120, 50>10>300>100>0kg/10a in Pike, and 50>100>10>0>300kg/10a in Pioneer brand 5929. Total dry matter yields at 50kg/10a lime application level were higher than those at any other levels in all the cultivars. Neither a specific pattern nor a significant change in inorganic composition of the plant was found for the lime application levels and cutting times, Soil chemical properties and composition remained with little change after the experiment except the soil pH, which was increased with the lime application level.

• Journal of Practical Agriculture & Fisheries Research
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• v.13 no.1
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• pp.71-82
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• 2011

This study was conducted to investigate the effect of stem node number, pinching time and growth retardants on the growth of Coreopsis spp. and Dianthus spp. Thy day of seedings are not passed period of 4 weeks after seedlings in the Cutting number and the days seedlings of joint experiments of Coreopsis spp. 2 node ranches treatment of Coreopsis spp. are reasonable valuable as ornamental pot product. Pinching time of Coreopsis spp. was more effectiveis on lateral and growth inhibition in the two times pinching treatment. It is observed that plant growth inhibitors was affected the growth of Coreopsis spp. It is observed that B-9 treatment is the effective plants growth and differentiation, especially the 2 times treatment with 4,000 ppm was the most effective. On the other hand, CCC treatment showed significant differences. B-9 treatment of Coreopsis spp was more effectived than the other treatment. Pinching and plant growth inhibitors of Dianthus spp. was not good the growth and plant height. Compared with B-9 4,000 ppm 2 times and control increased leaves extremely. it confirmed that the things are positively affective.

• Journal of Korean Society of Forest Science
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• v.1 no.1
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• pp.22-29
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• 1962

(1) The objects of this study are to observe the possibility of regenerating a young merchantable pitch pine stand by sprouts and to compare the growth trend of sprouts with that of seedlings of same age grown under the almost same circumstances. (2) A plot of 20 year old pitch pine plantation, i.e. 200 trees on 0.1 ha of average D.B.H. 14 cm was clearcut at 20 cm above ground in April, 1945. By the late spring of that year sixty per cent of the cut stumps had sprouted. (3) Fourty to eighty sprouts were found on each stump (maximum:412 sprouts) at the first, but many of them had gradually died out leaving only four to five sprouts per stump by the time of three years after cutting. At that time only one vigorous sprout was left per stump by eliminating the weaker ones. (4) The sprouts, as they grew, started to cover the old stumps with new tissues developed from lower part of sprouts;consequently forming new root systems from the base of new tissues, and they appeared to be seedlings. When the age of sprouts was thirteen years old, the old stumps were completely decayed away and the reproduced stand from sprouts was averaged at 9.7 cm in D.B.H. and at 5.5m in height. (5) When the age of sprouts was thirteen years old, the sprouts exceeded the seedlings in both of total present growth and mean annual increment in height, volume, D.B.H. and basal area, but the seedlings began to exceed the sprouts in current annual increment of height, volume, D.B.H. and basal area at about ten years of age. The rates of increment of the seedling in height, volume, ect. were larger than those of sprouts except when they were one to four years old. From above facts, the following may be concluded: (1) In regenerating a pitch pine stand by sprouts, the lower the stump height, the better the result. (2) If no light limit exists, regenerating a pitch pine stand by sprouts is well possible even at the age of 20 year. (3) Pitch pine reproduction started from sprouts exceeds the seedlings of same age in growth under the almost same circumstances until they get ten years of age.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.1
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• pp.69-89
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• 1981

Stevia (Stevia rebaudiana Bertoni) is a perennial herb widely distributed in the mountainous area of Paraguay. It belongs to the family Compositae and contains 6 to 12 percent stevioside in the leaves. Stevioside is a glucoside having similar sweetening character to surgar and the degree of sweetness is approximately 300 times of sugar. Since Korea does not produce any sugar crops, and the synthetic sweetenings are potentially hazardous for health, it is rather urgent to develop an economical new sweetener. Consequently, the current experiments are conducted to establish cultural practices of stevia, a new sweetening herbs, introduced into Korea in 1973 and the results are summarized as followings: 1. Days from transplanting of cuttings to the flower bud formation of 6 stevia lines were similar among daylengths of 8, 10 and 12 hours, but it was much greater at daylengths of 14 or 24 hour and varietal differences were noticable. All lines were photosensitive, but a line, 77013, was the most sensitive and 77067 and Suweon 2 were less sensitive to daylength. 2. Critical daylength of all lines seemed to be approximately 12 hours. Growth of plants was severely retarded at daylengths less than 12 hours. 3. Cutting were responded to short daylength before rooting. Number of days from transplanting to flower bud formation of 40-day old cuttings in the nursery bed was 20 days and it was delayed as duration of nursery were shorter. 4. Number of days from emergence to flower bud formation was shortest at short day treatment from 20 days after emergence. It was became longer as initiation of short day treatment was earlier or later than 20 days. 5. Plant height, number of branches, and top dry weight of stevia were reduced as cutting date was delayed from March 20 to May 20. The highest yield of dry leaf was obtained at nursery duration of 40-50 days in march 20 cutting, 30-40 days in April 20 cutting, and 30 days in May 20 cutting. 6. An asymptotic relationship was observed between plant population and leaf dry weight. Yield of dry leaf increased rapidly as plant population increased from 5,000 to 10,000 plants/10a with a reduced increasing rate from 10,000 to 20,000 plants/l0a, and levelled off at the plant population higher than 20,000 plants/l0a. 7. Stevia was adaptable in Suweon, Chengju, Mokpo and Jeju and drought was one of the main factors reducing yield of dry leaf. Yield of dry leaf was reduced significantly (approximately 30%) at June 20 transplanting compared to optimum transplanting. 8. Yield of dry leaf was higher in a vinyl house compared to unprotected control at long daylength or natural daylength except at short day treatment at March 20. Higher temperature ill a vinyl house does not have benefital effects at April 20 transplanting. 9. The highest content of stevioside was noted at the upper leaves of the plant but the lowest was measured at the plant parts of 20cm above ground. Leaf dry weight and stevioside yield was mainly contributed by the plant parts of 60 to 120cm above ground but the varietal differences were also significant. 10. Delayed harvest by the time of flower bud formation increased leaf dry weight remarkably. However, there were insignificant changes of yield as harvests were made at any time after flower bud formation. Content of stevioside was highest at the time of flower bud formation and earlier or later harvest than this time was low in its content. The optimum harvesting time determined by leaf dry weight and stevioside content was the periods from flower bud formation to right before flowering that would be the period from September 10 to September 15 in Suweon area. 11. Stevioside and rebaudioside content in the leaves of Stevia varieties were ranged from 5.4% to 14.3% and 1.5% to 8.3% respectively. However, no definit relationships between stevioside and rebaudioside were observed in these particular experiments.

• Journal of Korean Society of Forest Science
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• v.109 no.2
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• pp.179-188
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• 2020

Weeding refers to the process of removing weeds around crop trees, which cause competition in nutrients, moisture, and light, and has a great effect on the early growth and survival of crop trees for establishing forest resources. This study was conducted to find out the timing and method of weeding that is the most suitable for the major afforestation species in national forests. We investigated (1) weeding time and frequency for each afforestation species and (2) the height of crop trees and the length of weeds. Up to 99% weeding operation was carried out until 5 years following afforestation. Pinus densiflora, Larix kaempferi, Chamaecyparis obtusa, Prunus sargentii, and Betula platyphylla plantations accounted for more than 70% of the total weeding sites. Once-a-year weeding process was conducted from late June to late July (67%), and twice-a-year weeding process was the highest in June-August by 31%. Most species were shorter than the weeds until the first and second year of planting, but the height of the crop trees was higher than that of the weeds by 48% in average from the third year. Therefore, from the third year of afforestation, except for some species, it is possible to reduce the cost of weeding operations while reducing nutrient competition by the weeds through the removal of weed sprouts, mainly woody weeds, rather than clear cutting. This study contributes to efficiently develop forest resource establishment while reducing operational costs through a detailed weeding schedule and species-specific method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.677-686
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• 2016

A thermal power plant is the first CFBC (Circulating Fluidized Bed Combustion) power plant consisting of 2 boilers-1 turbine. The optimal height of a stack needs to be approximately 156 meters in the case of this thermal power plant; however, the thermal power plant sites satisfy a function and reduce the construction cost by using mountains in the sites after cutting the ground and locating an integrated office and chimney at an altitude of 70 meters thereby lowering the height of the stack to 86 meters. In addition, the integrated office, which has a combined stack style with a unique design, is constructed by connecting with 2 stacks and disposing the office and an observatory in the space between them. Therefore, this study examined the design concept that fulfils the structural, functional, and aesthetic factors, harmoniously by joining the integrated office and the stack, which are disparate, and investigated special construction methods (Slip Form, Steel Inner Flue & Lift-up) through which heterogeneous architectures are structurally, functionally, and aesthetically constructed.

• Korean Journal of Plant Resources
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• v.16 no.2
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• pp.99-108
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• 2003

This study was carried out to make a standard criteria for protection and maintenance of the big and old trees in Ansung city, Kyonggi Prvince. There have been found 6 vegetative species cultivated in this area, which are Zelkova serrata, Gingko biloba, Kalopanax pictus, Pyrus ussuriensis var. macrostipes, Pyrus ussuriensis var. acidula, Pinus densiflora, etc. The Zelkova serrata tree is the major species among them and about 73.5％ in the population of the big and old trees in this area. The DBH (diameter at brest height) of them is 1.5-1.9m in 29.4% of whole population and the tree height is 10-l4m in 47.1%. The estimate age of 7 trees is more than 500 years old and they were 20.6％ of the whole population. Interesting point is that about 64.7％ of these trees in this area have own succeed story in terms of folk religion, object of worship, taboo, legend or secret. This study has also revealed that many fowls, small animals and epiphyte inhabited with the big and old trees have been found. However, 97.1％ of them are in danger from the plant disease and noxious insects or cutting damage of branches, but no management has been taken. More over, 85.3％ of the whole investigated big and old trees have been in the poor condition for percolation or aeration because the area around them has been payed with asphalt or concrete.

• Journal of Korean Society of Forest Science
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• v.99 no.1
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• pp.153-162
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• 2010

Abies holophylla Maxim. is a shade tolerant species that has potential to be used for continuous cover forestry system. Stand structure and natural regeneration of A. holophylla stands in Yong-In area located in the central part of Korea was investigated to estimate the self sustainability of A. holophylla plantation. Species composition, diameter at breast height (DBH) and height distribution of trees larger than 2 cm DBH were measured in ten stands in three study sites of Jeongsu-ri, Daedae-ri, and Hodong. Species and coverage of shrub layer, and A. holophylla seedlings were also investigated. While A. holophylla in non-managed stands (Jengsuri and Daedae-ri study sites) had the importance value of 40% and showed continuous diameter and age distribution, A. holophylla in Hodong site had narrow bell-shaped DBH distribution mostly concentrating between 25-35 cm DBH classes, and single canopy structure. Abies holophylla stands in Hodong have experienced occasional thinning and selective cutting. The correlation coefficient between age-DBH was significant but low ($R^2$=0.2, P=0.03), and similar aged A. holophylla had diverse DBH values. Continuos DBH distribution and multi-canopy structure of A. holophylla stands in Jeongsu-ri site show that natural regeneration of A. holophylla has been continuously occurred in this area. Seedling density of A. holophylla was between 2000 and 33000/ha, however, the number of trees in 2-5 cm DBH class was only 40-150 trees/ha, implying that the survival rate of seedlings is not high. Continuous natural regeneration and 0.6 cm/year of diameter growth rate of A. holophylla indicate that this area could be an appropriate habitat for this species, and A. holophylla plantation in this region seem to persist suggesting the possibility of managing the stands for continuous cover forestry system as well as selective harvesting practices.

• Journal of Korean Society of Forest Science
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• v.87 no.2
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• pp.173-178
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• 1998

Twelve Camellia sinensis populations were studied to investigate the biomass distribution related to stand structure. With increasing mean age of the population, mean root collar diameter increased, while mean height, density and root collar area had no correlation with the age. The result of dimension analysis after cutting the sample trees showed that dry weights of stems +branches and root were exponentially increased and dry weights of current leaves and twigs were linearly increased with increasing root collar diameter. However, the dry weight of older leaves was not related to the root collar diameter. The range of total biomass was 1,162~11,474kg/ha and the range of current leaf biomass was 165~1,341kg/ha. The range of T/R ratio was 1.5~2.8. The biomass of stems+branches and root were significantly correlated with the root collar area of the population and were not significantly correlated with the mean age, mean root collar diameter and density of the population. The biomass of current leaves and twigs were significantly correlated with the root collar area and density of the population.