• Korean Journal of Environmental Agriculture
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• v.40 no.2
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• pp.73-82
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• 2021

BACKGROUND: The successful management of jujube trees depends on maintaining a balance between reproductive and vegetative growth. In general, heading cuts of trunk stimulate rather vegetative growth, but could decrease flower initiation. This study was conducted to establish a heading-back pruning severities at planting in the one year old 'Daeneung' jujube whip nursery tree by investigating vegetative growth and fruit yield. METHODS AND RESULTS: The heading back pruning severity was assigned as 5 different ranges as follow: one bud (TR-10, heading back pruning was 10 cm above the ground), three buds (TR-30), five buds (TR-50), seven buds (TR-70), and nine buds (TR-90) were left of scion. The number of buds on whip trunk was correlated to the central leader length and increment of trunk cross-sectional area, negatively, and to the tree height and canopy volume, positively. The yields in the TR-50 treatment were higher about 2 times than other treatments. The fruit diameter was not significantly different among the treatments. CONCLUSION: These results indicated that the optimum location of heading-back pruning in one year old 'Daeneung' jujube tree was 50 cm above the ground as evaluated by the balance of reproductive and vegetative growth.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.183-183
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• 2017

In the early part of rice growth, root volume primarily limits the amount of plant-accessible nitrogen (N). Therefore, knowledge of the root development is important for modeling N uptake of rice. The timing when the volume of rhizosphere cover the whole soil is also important to carry out timely top dressing. However, information about initial root expansion and associated N uptake is limited due to intrinsic technical difficulties in assessing below-ground processes. Some studies, however, showed a close relationship between below-ground root and above-ground leaf development, suggesting a possibility that above-ground attributes could serve as surrogates for the root processes. In this study, we investigated the relationship between below-ground and above-ground development of rice. Field experiments were conducted where we cultivated Koshihikari (a leading cultivar in Japan) for four different cropping schedules in 2012. In 2016, Gimbozu (HEG4) and three flowering time mutant lines of Gimbozu (X61 (se13), HS276 (ef7), DMG9 (se13, ef7)) were examined for a single season. Experiments were performed with three replications in a completely randomized design. We monitored ammonium-N concentration ([NH4+-N]) in soil solution by repeatedly taking samples from a porous tubing (10-cm long) vertically inserted at the most distant point from surrounding rice hills. Samples were taken in triplicate (= triplicate tubes) and every three days from transplanting in each experimental unit. For above-ground attributes, leaf area index (LAI) was measured in 2012, whereas soil coverage ratio was estimated by image processing in 2016. Results showed that [NH4+-N] increased gradually after transplanting and then rapidly decreased from a certain day. This distinct drop in [NH4+-N] informed us the timing at which the rice root system reached the point of porous tubing and thus essentially covered the whole soil volume. The LAI at the dropping point was about 0.43 regardless of the cropping schedules in 2012 experiment. In 2016, the coverage ratio at the N dropping point was within the range of 0.12 to 0.19 for four genotypes having different growth durations. In addition, the coverage ratios at seven weeks after the transplanting showed a good correspondence to LAI across the four genotypes. We therefore conclude that both LAI and coverage ratio may serve as robust indicators for root development and might be useful to estimate the timing when the root system fully cover the soil volume. Results obtained here will also contribute to develop models that can predict not only above-ground canopy development but also associated below-ground processes.

• Proceedings of the KSRS Conference
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• v.1
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• pp.512-515
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• 2006

Forest stand height and volume are important indicators for management purpose as well as for the environmental analysis. Shuttle Radar Topography Mission (SRTM) is backscattered over forest canopy and DSM can be acquired from such scattering characteristic, while National Elevation Dataset (NED) provides bare earth elevation data. The difference between SRTM and NED is estimated as tree height, and it is correlated with forest parameters, it is correlated with forest parameters, including average DBH, Trees per acre, net BF per acre, and total Net MBF. Especially, among them, net Board Foot(BF) per acre is the index that well represents forest volume. The Project site was Douglas-fir dominating plantation area in the western Washington an the northern Oregon in the U.S. This study shows a relationship of high correlation between the forest parameters and the product from SRTM, NED, and ETM+. This research performs multi regression analysis and regression tree algorithm, and can get more improved relationship between several parameters.

• Korean Journal of Remote Sensing
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• v.22 no.5
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• pp.427-431
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• 2006

Forest stand height and volume are important indicators for management purpose as well as for the environmental analysis. Shuttle Radar Topography Mission (SRTM) is backscattered over forest canopy and DSM can be acquired from such scattering characteristic, while National Elevation Dataset (NED) provides bare earth elevation data. The difference between SRTM and NED is estimated as tree height, and it is correlated with forest parameters, it is correlated with forest parameters, including average DBH, Trees per acre, net BF per acre, and total Net MBF. Especially, among them, net Board Foot(BF) per acre is the index that well represents forest volume. The Project site was Douglas-fir dominating plantation area in the western Washington an the northern Oregon in the U.S. This study shows a relationship of high correlation between the forest parameters and the product from SRTM, NED, and ETM+. This research performs multi regression analysis and regression tree algorithm, and can get more improved relationship between several parameters.

• Journal of Biosystems Engineering
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• v.26 no.5
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• pp.431-440
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• 2001

Generated agri-chemical droplets by orchard sprayers are evaporated regenerated and transported along wind streams. The droplets are deposited to targets after changing their sizes, affecting the retention of droplets. An orchard sprayer, designed for spraying grapevines was studied on the spatial distribution of droplet size. The experimental variables were spray direction (0, 22.5, 45, 67.5 and 90˚), distance(2.5, 3.0 and 3.5 m) and fan speed (2,075 and 3,031 rpm). Droplet sizes were converted and analyzed from spray stains, sampled using water sensitive papers. The number median diameter (NMD) increased with an increase of the distance due to disappeared fine droplets (<50 ㎛): however, the volume median diameter (VMD) decreased due to shrunken large droplets (>100 ㎛). Fast fan speed delivered large droplets to 3.5 m, but the spatial distributions of NMD and VMD were not uniform. Slower fan speed decreased the possibility of evaporation and drift; therefore, plenty of droplets were maintained up to 3.0 m. The upward blasting distance was limited within 3 m, but the limit to the ground level was extended to 3.5 m. Concentrated wind and droplets to the ground level should be redistributed to upper canopy direction, leading more uniform deposits. High speed wind and system pressure should be avoided because of generating fine droplets, which would be disappeared and drifted away.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.332-335
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• 2008

Newly developing SAR (Synthetic Aperture Radar) sensors commonly include high resolution X-band those data are expected to contribute various applications. Recent few studies are presenting potential of X-band SAR data in forest related application. This study tried to investigate the relationship between forest stand parameters and multi-band SAR normalized backscattering. Multi-band SAR data was radiometric corrected to compare signal from different forest stand condition. Then correlation coefficients were estimated between attribute of forest stand map and normalized backscattering coefficients. Although overall correlation coefficients are not high, only X-band shows strong relationship with DBH class than other bands. The signal of C- and L-band is composed of a large number of discrete tree components such as leaves, stems, even background soil. In forest, strength of radar backscattering is affected by complex parameters. Further study might be considered more various forest stand parameters such as canopy density, stand height, volume, and biomass.

• Horticultural Science & Technology
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• v.33 no.2
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• pp.155-165
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• 2015

Well-feathered (over 10 feathers) 'Fuji'/M.9 apple trees were planted at $3.0{\times}1.0m$ and trained to slender spindle with 2.5 m height or to tall spindle with 3.5 m height, and the vegetative growth, productivity, and fruit quality of two training systems were compared for 8 years. The canopy volume of the tall spindle trees surpassed that of the slender spindle trees 4 years after planting and was 25% larger than that of the slender spindle trees 5 years after planting. The accumulated yield over 8 years for the tall spindle system was 14% higher than that of the slender spindle system. Alternate bearing and incidence of marssonina blotch were observed in both treatments after 5 years of planting. There was often vegetative imbalance in the trees however, the degree of yield loss and vegetative imbalance of the tall spindle trees was lower than those of the slender spindle trees. Soluble solid content and fruit red color of the tall spindle trees were higher than that of the slender spindle trees in 5 year after planting, resulting from increased light penetration in the canopy due to even distribution of lateral branches and from fruit bearing in different height locations of the trees. In conclusion, increasing the tree height to about 3.5 m using slender spindle 'Fuji'/M.9 apple trees planted with over 333 trees per 10a led to better light penetration, yield and fruit quality compared to a conventional wide training system with the slender spindle.

• Korean Journal of Environment and Ecology
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• v.25 no.5
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• pp.639-648
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• 2011

We recorded the movement of wildbirds nine times at Hoam 1st Tunnel, Kkachisan Park, Deungneung pass to compare the movement between eco-corridor and neighboring crossing road from June to September, 2006. Among three areas, birds did not prefer the eco-corridor at pass type such as Kkachisan Park and Deungneung pass, however number of species and individuals were high at the eco-corridor at Hoam 1st Tunnel. Over 90m width and the slope location of eco-corridors can be beneficial for wild birds to enhance the movement along eco-corridors between isolated two patches. Average foliage volume under two meters showed the relation with bush nesters, and that from 7 to 8m had the highest relationship with canopy nesters. In Seoul city, target species should be considered at the construction of eco-corridors according to site characteristics, but Paradoxornis webbianus could be suggested as a main target species at eco-corridors. To enhance the movement of diverse wildbirds, we would implement that eco-corridors could be located at the slope area with the size of 1ha (over 90m width), eco-corridors could be planted and managed with the high foliage volume of shrub layer under twometers and canopy layer over 8 meters.

• Journal of the Korean Solar Energy Society
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• v.29 no.5
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• pp.35-44
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• 2009

In this study, boiling heat transfer coefficients(HTCs) and critical heat flux(CHF) are measured on a smooth square flat copper heater in a pool of pure water with and without carbon nano tubes(CNTs) dispersed at $60^{\circ}C$. Tested aqueous nanofluids are prepared using multi-walled CNTs whose volume concentrations are 0.0001, 0.001, 0.01, and 0.05%. For dispersion of CNTs, polyvinyl pyrrolidone(PVP) is used in distilled water. Pool boiling HTCs are taken from $10kW/m^2$ to critical heat flux for all nanofluids. Test results show that the pool boiling HTCs of the nanofluids are lower than those of pure water in entire nucleate boiling regime. On the other hand, critical heat flux is enhanced greatly showing up to 200% increase at volume concentration of 0.001% CNTs as compared to that of pure water. This is related to the change of surface characteristics by the deposition of CNTs. This deposition makes a thin CNT layer on the surface and the active nucleation sites of heat transfer surface are decreased due to this layer. The thin layer acts as the thermal resistance and also decreases the bubble generation rate resulting in a decrease in pool boiling HTCs. The same layer, however, maintains the nucleate boiling even at very high heat fluxes and reduces the formation of large vapor canopy at near CHF resulting in a significant increase in CHF.

• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.626-648
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• 2021

Domestically, demands for multi-purpose performance venues which accommodate various performance genres have increased. However, those venues have limited capability and confined to a primary performance. The present work investigated various methods for controlling the acoustics of room for required performance genres by reviewing aurally presented and published materials. The method of varying the acoustics of a space is called Variable Acoustics, and adjusted in either passive and active ways. Passive control encompasses variable absorption, variable volume, coupled volume, and canopy reflectors, where the acoustics of a room is controlled in an architectural way. Active control includes In-line, Regenerative, and Hybrid systems where the acoustics of a room is manipulated electronically. The mechanism and application of each passive control system in existing venues are reviewed and their pros and cons are discussed. Also, the concept of each active systems and product applications are looked at through literature reviews. Lastly, some considerations that need to be taken into in the planning and design stage of a multi-purpose hall using Variable Acoustics are suggested.