• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.65 no.2
• /
• pp.151-155
• /
• 2020

This study was conducted to determine the effects of the selection of an appropriate sowing method in on ginseng growth, and the results are as follows. SAS (semi-automatic sower), commonly used by direct seeding farms, provides fast operation speed but results in high labor cost, while (Hooper Seeder Sowing) offers fast operation speed and high germination rate, but leads to increased laborer's fatigue. Daily working area per sower was 6,611 ㎡ for a motor type, and the operation time to sow 3,305 ㎡ was 15 hours for broadcast planting, and 8 hours for SAS. The germination rate of 1-year-old ginseng according to direct seeding was 69.1% for the treatment plot under broadcast planting, followed by 66.4% and 67.3% for manual sower and hoop sower, respectively, and the germination rate of SAS was the lowest at 64.2%. In addition, there were no differences in shoot and root growth of 1-year-old ginseng among the sowing methods. Therefore, the sowing method can be chosen depending on the economic size of ginseng farmers. That broadcast sowing (BS) is appropriate for small scale farmers, while motor-driven seeder sowing (MDS) for direct seeding is more suitable for large scale farmers.

• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.612-619
• /
• 2002

The dynamic behavior of Al-Mg alloys plasma was very unstable and this instability was closely related to the unstable motion of keyhole during laser irradiation. The keyhole fluctuated both in size and shape and its fluctuation period was about 440 ${\mu}{\textrm}{m}$. This instability has been estimated to be caused by the evaporation phenomena of metals with different boiling point and latent heats of vaporization. Therefore, the authors have conducted the spectroscopic diagnostics of plasma induced in the pulsed YAG laser welding of Al-Mg alloys in air and argon atmospheres. In the air environment, the identified spectra were atomic lines of Al, Mg, Cr, Mn, Cu, Fe and Zn, and singly ionized Mg line, as well as strong molecular spectrum of AlO, MgO and AIH. It was confirmed that the resonant lines of Al and Mg were strongly self-absorbed, in particular in the vicinity of pool surface. The self-absorption of atomic Mg line was more eminent in alloys containing higher Mg. These facts showed that the laser-induced plasma was relatively a low temperature and high density metallic vapor. The intensities of molecular spectra of AlO and MgO were different each other depending on the power density of laser beam. Under the low power density irradiation condition, the MgO band spectra were predominant in intensity, while the AlO spectra became much stronger in higher power density. In argon atmosphere the band spectra of MgO and AlO completely vanished, but AlH molecular spectra was detected clearly. The hydrogen source was presumably the hydrogen solved in the base Metal, absorbed water on the surface oxide layer or H$_2$ and $H_2O$ in the shielding gas. The temporal change in spectral line intensities was quite similar to the fluctuation of keyhole. The time average plasma temperature at 1 mm high above the surface of A5083 alloy was determined by the Boltzmann plot method of atomic Cr lines of different excitation energy. The obtained electron temperature was 3, 280$\pm$150 K which was about 500 K higher than the boiling point of pure aluminum. The electron number density was determined by measuring the relative intensities of the spectra1lines of atomic and singly ionized Magnesium, and the obtained value was 1.85 x 1019 1/㎥.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.23 no.1
• /
• pp.51-57
• /
• 2013

We have applied mechanical alloying (MA) to produce Heusler $Fe_2VAl$ thermoelectric alloy using a mixture of elemental $Fe_{50}V_{25}Al_{25}$ powders. An optimal milling and heat treatment conditions to obtain the single phase of Fe2VAl compound with fine microstructure were investigated by X-ray diffraction and differential scanning calorimetry (DSC) measurement. The $Fe_{50}V_{25}Al_{25}$ MA sample ball-milled for 60 hours exhibits a bcc ${\alpha}$-(Fe,V,Al) solid solution. Single phase of Heusler $Fe_2VAl$ compound can be obtained by MA of $Fe_{50}V_{25}Al_{25}$ mixture for 60 hours and subsequently heated up to $700^{\circ}C$. Sintering of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies at $900{\sim}1000^{\circ}C$ under 60 MPa. The Vickers hardness of bulk sample sintered at $1000^{\circ}C$ was high value of Hv 870. All compact bodies have a high relative density above 90 % with metallic glare on the surface.

• Journal of Korean Society of Forest Science
• /
• v.101 no.2
• /
• pp.175-184
• /
• 2012

This study was conducted to develop new mattress systems with vegetation base materials for protecting stream bank and rapid rehabilitation. Vegetation base materials are primarily compounded with fine soil, organic composts and peat moss as plant fibers, a water retainer and a soil improver. Peat moss can usually provide necessary natural fibers and organic materials in soil. Especially, peat moss can absorb up to 25 times its own weight in water and is therefore valued as a water retainer to prevent drying effect of vegetation base materials which can harm the growth of vegetation in mattresses. Normally mattress systems resist the lateral earth pressures or stream power by their own weight. Therefore, filled materials must have suitable weight, compressive strength and durability to resist the loading, as well as the effects of water and weathering. In this project, 100 to 200-mm clean, hard stones were basically specified, and about 50-mm rubbles were also used. Test application of new mattress system carried out in the stream bank of a small stream in the Gwangreung experimental forest, belonging to Korea Forest Research Institute (KFRI) in December 16th, 2006. As a result of the monitoring of vegetation coverage of test application plots (each plot size is 4 by 2 m), the coverage of all plots reached 100% in the end of May, 2007 (approximately 50 days passed after the first gemination of vegetation). The coverage of the plots using big hard stones and organic composts and the plots containing peat moss increased more rapidly. The results show that peat moss is effective to retain soil moisture and establish more sound environment for vegetation gemination.

• Journal of Korean Society of Forest Science
• /
• v.70 no.1
• /
• pp.72-76
• /
• 1985

Populus alba ${\times}$ P. glandulosa cuttings in nursery bed were inoculated with mycelium of ectomycorrhizal fungus, Pisolithus tinctorius (Pt) to evaluate effectiveness of the fungus in growth stimulation of poplar. Pt was cultured in 1l glass bottles with vermiculite-peatmoss mixture moistened with modified Melin-Norkrans' solution. The nursery bed was arranged for microplots of $1{\times}2m$ in size and fumigated with methyl bromide before inoculation and cutting placement. Fifty cuttings were placed in each microplot and two treatments (fumigation only and fumigation plus Pt inoculation) were replicated three times. At the end of the first growing season, inoculated plants grew 19% faster in height and produced 49% more dry weight (above-ground portion) than uninoculated plants. Survival rate of inoculated cuttings was also improved by 20% over that of uninoculated cuttings. Inoculated cuttings developed abundant fine root system with golden brown zigzag tips. In the middle of September a sporocarp of Pt was produced from an inoculated plot, suggesting successful establishment of mycorrhiza between poplar and Pt fungus.

• Journal of Navigation and Port Research
• /
• v.38 no.2
• /
• pp.185-191
• /
• 2014

With the 500th anniversary commemoration of Gerard Mercator's birth in 2012 now passed, there is the possibility that his name will fade back into obscurity. This would be both unfair and pitiful, because Gerard Mercator's name should be highly regarded as one of the principal contributors to navigational science and the promotion of marine safety. An accomplished cartographer, in 1569 Mercator published a remarkable 18-folio world map, depicting the then-known world in a new format with straight rhumb lines. While this distorted the size of land masses, particularly in higher latitudes, this new projection made navigation much easier for now all sailors had to do was to draw a straight line between two points to plot their course. Mercator clearly had this navigational benefit in mind, though his contemporaries did not immediately recognize its value. It wasn't until after Mercator's death, when Edward Wright (1599) and Henry Bond (1645) used and explained the new projection and demonstrated the use of straight rhumb lines in navigation that the Mercator projection became the standard for sea charts. Today, 450 years later of his death, electronic charts still rely on the projection Mercator invented and developed, confirming his position as a giant in the history of navigation. This paper introduces his life and work, detailing the importance of the 1569 world map and its contribution to navigational science and safety.

• Korean Journal of Agricultural Science
• /
• v.9 no.2
• /
• pp.494-506
• /
• 1982

The community structure and dynamic succession of forest were determinated on the quadrat plots selected randomly at the Mt. Bomun. The plot size was $20{\times}20m$, and analysis of vegetation and soil 'data we re adapted reciprocal averaging(RA) ordination method. 1. The numbers of tree species were twenty, and dominant species were Quercus variabilis, Pinus densiflora, Alnus hirsuta, and Pinus rigida. 2. The forest of Mt. Bomun was found to be composed of Pinus rigida community and Quercus-Pinus community through RA ordination method. 3. The community of Quercus variabilis was assumed to be dominant in the succession of forest. 4. The soil factors, such as total-N, $NO_3$, $NH_4^+$, $P_2O_5$, organic matter, C. E. C., pH, $K^+$, $Ca^{{+}{+}}$ and $Mg^{{+}{+}}$, were analyzed. Total-N, $NO_3^-$, $NH_4^+$, and $P_2O_5$ were assumed to be the main factors of the soil.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.207-207
• /
• 2017

The proso millet is vulnerable to lodging due to high plant height and shallow root. A lodging results in a hard mechanical harvesting and yield loss. One of solutions on this problem is inhibition of internode elongation. The objective of this study was to set up use time and dose of prohexadium-calcium, is growth inhibitor. The experimental variety was Ibaekchal. The experiment design was a split-plot design with three replications. The treatments were as follow: Main-plots were 25 and 35 day after sowing(DAS) as use time and sub-plots were 0%, 50%, 100%(diluted solution of 1000 times, $1000{\ell}\;ha^{-1}$), 150% as dose. The amount of nitrogen, phosphate and potassium fertilization were 90, 70, $80kg\;ha^{-1}$, respectively. The size of high ridge and plant spacing were $90{\times}30cm$ and $60{\times}15cm$, respectively. Proso millet was sown on June 9, 2016 by hands and was adjusted at 2 plant per hill. The growth survey of vegetative growth stage was conducted at 1 day before treatment and with one week interval after treatment. Data were collected: (1) grain yield: weight of grain in $kg\;ha^{-1}$, (2) 1000 grain weight: average weight of 1000 grain, (3) plant height: distance from soil to top of panicle or leaf in cm, (4) ear length: distance from top of stem to top of ear in cm, (5) stem diameter: diameter of second internode (6) degree of lodging: percentage of lodging area, etc. Analyses of variance were performed using R version 3.3.1(https://www. r- project. org). The Duncan's multiple range test(DMR) was used to separate treatment means at P < 0.05. There was a significant difference in plant height and number of stem among the use time and dose of prohexadium-calcium during vegetative growth stage. At 25 DAS, the difference with no treatment increased until 25 day after treatment and decreased since then. The difference in number of stem increased until 18 day and decreased since 25 day. At 35 DAS, the difference with no treatment in plant height and number of stem increased until 22 day after treatment and decreased since then. We assumed that the effect of prohexadium-calcium was inhibition of internode elongation and promotion of tillering, continued untel 25day after treatment. At 25 DAS, the degree of lodging deceased to 100%, 30%, 10% and 0% as dose increased. At 35 DAS, the degree of lodging decreased to 100%, 20%, 0% and 0% as dose increased. At 25 DAS, the yield was 2910, 2710, 3190, $2310kg\;ha^{-1}$ among dose. At 35 DAS, the yield was 2750, 2630, 2220, $2050kg\;ha^{-1}$. We recommend that the optimum use time and dose of prohexadium-calcium for proso millet is 1000 times diluted solution of $1000{\ell}$ per ha at 25 day after sowing.

• Journal of Korean Society of Forest Science
• /
• v.87 no.3
• /
• pp.383-390
• /
• 1998

The purpose of this study was to evaluate the effect of new materials with forest topsoil for hydroseeding measures that is environmentally and ecologically stable revegetation measures on rock cut-slopes. Field hydroseeding experiment was used with a completely randomized design at highway rock cut-slopes in April, 1997. Results obtained in this study were summarized as follows: Particle size distribution of 3 mixed-soil materials that consisted of forest topsoil, decomposed granite soil, compost, sludge, and bottom ash did not show a significant difference. As appending the amount of forest topsoil, soil bulk density was increased. Soil hardness was slightly increased in early period, and then decreased with the flourishing of plants. The number of individuals increased, more than $3,000seedlings/m^2$, after 1 month, and it was decreased as time passes because of competition between the seeded species and the naturally emerged species. In addition to the seeded species, seeding plot has more than 6 species (Rubus crataegifolius, Eleusine indica, Erigeron canadensis, Lycopersicon esculentum var. cerasiforme, etc.) per $m^2$ were naturally appeared in the first year. From the viewpoint of species diversity promotion, the capability of using forest topsoil as seed bank sources was high. In order to apply in the field, the investigation and analysis of topsoil availability (quantity and quality of seed source, soil texture and organic composition) should be carried out before-hand.

• Journal of Korean Society of Forest Science
• /
• v.69 no.1
• /
• pp.28-35
• /
• 1985

To estimate the aboveground biomass of Pinus rigida and Pinus rigida ${\times}$ taeda 22-year-old plantations, the experimental plots of $200m^2$ in size located in Kwangju of Jeonlanam-do were selected. Nine sample trees selected at each plot taking account of DBH distribution were felled and the diagram of oven-dry weight distribution of stem, branch, and needle for each 1m segment was constructed. The logarithmic regression equations between dry weight of each component (stems, branches, and needles) and the variable of $(DBH)^2{\cdot}H$ were obtained. The aboveground standing crops was estimated to be as much as 71.61 and 142.32 tons of dry matter per hectare in P. rigida and P. rigida ${\times}$ taeda stand respectively. The net production was estimated as 10.81 and 10.46 t/ha/yr and the net assimilation rate 1.32 and 1.00 kg/kg/yr in P. rigida and P. rigida ${\times}$ taeda stand respectively. And the efficiency of needles to produce stem was 0.97 and 0.81 kg/kg/yr in same order.