• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.3
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• pp.151-162
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• 2013

Studies of the distribution of micro-phytoplankton community and chlorophyll a concentration have focused on the vertical profiles of marine environmental factors such as water temperature, salinity, sigma-t, light intensity, and dissolved oxygen in the continental slope on the east parts of East China Sea in the early summer of 2009. Water temperature showed a gradual reduction according to the depth. While the salinity was low in the surface layer showing a mixed down to the relatively subsurface layer, it was increased with an increase in the depth at the middle and bottom layers showing a maximum value at 150~200 m followed by a decreasing aspect afterwards, although the change was not large. The change of sigma-t was governed by the water temperature, and gradually increased in the surface layer with an increase in the depth, showing a value higher than in the surface layer by about 3 $kg/m^3$ at the bottom layer. Although the intensity of light was exponential reduced in the surface layer, the compensation depth was located at the depth of about 80m. The vertical profiles of chlorophyll a concentration was governed by the intensity rather than the changes in water temperature or salinity, exhibiting a maximum value at the compensation depth corresponding to 1% in the surface light intensity. The micro-phytoplankton communities consisted of 56 genera 103 species showing a relatively variety, while the standing crop was also changed to 112.0~470.0 cells/L in the pelagic environment, showing a maximum chlorophyll a concentration. Although a variety of dominant species appear at low dominance without dominant species appearing with a right-wing point in the phytoplankton communities, the silicoflagellate, Otactis otonaris at the station A and the dominance of 26% due to Leptocylindrus mediterraneus at the station C have been judged to be unusual. For community analysis of infinitesimal creatures such as phytoplankton of oligotrophic waters through the present study, ecology studies through vertical sample collection agreeing with the results of continuous observation such as identification of vertical distribution in a marine environment or of maximum chlorophyll layers have been considered rather than a survey method with intervals of a given depth such as surface, subsurface, middle and bottom layers.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.12-19
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• 1999

CERES-rice, a rice growth simulation model, was used in conjunction with daily weather data to figure out the spatial variation of the phenology and yields of paddy rice at 168 rice cultivation zone units(CZU) of Kyunggi Province in 1997. Two sets of cultivar specific coefficients, which represent early and mid-season maturing varieties, were derived from field experiments conducted at two crop experiment stations. The minimum data set to run the model for each CZU (daily maximum and minimum temperature, solar irradiance, and rainfall) was obtained by spatial averaging of existing 'Digital Map of Korean Climate'(Shin et al., 1999). Soil characteristics and management information at each CZU were available from the Rural Development Administration. According to a preliminary test using 5 to 9 years field data, trends of the phasic development(heading and physiological maturity), which were obtained from the model adjusted for these coefficients, were in good agreement with the observed data. However, the simulated inter-annual variation was somewhat greater than the reported variation. Rough rice yields of the early maturing cultivar calculated by the model were comparable with the reported data in terms of both absolute value and inter -annual variation. But those of the mid season cultivar showed overestimation. After running the simulation model runs with 1997 weather data for 168 CZU's, rough rice yields of the 168 CZU's calculated by the model were aggregated into corresponding 33 counties by acreage-weighting to facilitate direct comparison with the reported statistics from the Ministry of Agriculture and Forestry. The simulation results were good at 22 out of the 26 counties with reportedly increasing yield trend with respect to the past 9 years average.

• Journal of the Korean Wood Science and Technology
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• v.34 no.3
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• pp.90-98
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• 2006

The purpose of this study was to estimate natural dyeing properties of Korean traditional paper (Hanji). Korean traditional paper, which made from bleached bast fiber pulp of Broussonetia kazinoki was used as base paper. As dyestuffs, hot water extractives of Phellodendron amurense bark, Rosa multiflora leaf and stalk, and Rubia cordifolia root and methanol extractives of Lithospermum erytrorhizon root were used. $Al_2(SO_4)_3$ and $Fe(OH)(CH_3COO)_2$ 0.5% solution were used as mordant. Soybean juice (10%), chitosan (0.1%), and skim milk (2%) solutions were used as auxiliary dyeing agents. Accelerated aging treatments of natural dyed Korean traditional papers were undergone at following conditions: exposure temperature, $80^{\circ}C$ relative humidity, 60%; wavelength, 340 nm; UV irradiance, $0.67W/m^2/nm$ exposure time, 24, 48, and 72 hours. Colors, color difference, and color fastness were examined for estimation of natural dyeing characteristics. The auxiliary dyeing agents treated Korean traditional papers were more superior the dyeing effectiveness about dyestuffs than untreated Korean traditional papers. The dyeing effectiveness of soybean juice treated Korean traditional paper was superior to the others. The color fastness of Korean traditional paper, which was dyed with Rubia cordifolia root extractives, was most inferior to the others.

• Journal of Bio-Environment Control
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• v.9 no.3
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• pp.156-160
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• 2000

The Plasma film treated with a high electric voltage was developed to enhance flow down of condensation drops on inside plastic film. Arch type greenhouse framed with iron pipe of 25mm diameter defand 1.5mm thickness were covered with either the developed plasma film or surfactant film(control). Green pepper seedlings raised for 40 days in plug trays were transplanted at a density of 110cm by 30cm in each greenhouse. The mount of condensational water on film surface, generated by 7$0^{\circ}C$ water bath chimney systems and flew down, was collected and measured. The amount of collected water after 150 minutes was 2.56 mL.100c $m^{-2}$ and 0.94mL.100c $m^{-2}$ , respectively, in the plasma film and surfactant film-covered greenhouses. The amount of condensational water drops attached on the cover at 08:20 a.m. at 60 days filter covering was 0.34mL.100c $m^{02}$ and 0.32mL.100c $m^{-2}$ , respectively, in the plasma film- and surfactant film-covered greenhouses. Solar irradiance transmitted into greenhouse was 2.0% higher in the greenhouse covered with the plasma film tan that in the greenhouse covered with the surfactant film. Air temperature in the plasma film-covered greenhouse was higher than the surfactant film-covered greenhouse by 0.5$^{\circ}C$. However, there was no difference in relative humidity between the two greenhouse. Plant height, leaf area, dry weight and early yield showed no significant differences.s.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.239-246
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• 2021

Characteristics of hydrodynamics and heat absorption by gas in a directly-irradiated fluidized bed particle receiver (50 mm-ID X 150 mm high) of SiC particles have been determined. Solid holdups of SiC particles show almost constant values with increasing gas velocity. Fine SiC particles (SiC II; dp=52 ㎛, ρs=2992 kg/㎥) showed low values of relative standard deviation of pressure drop across bed but high solids holdups in the freeboard region compared to coarse SiC particles (SiC I; dp=123 ㎛, ρs=3015 kg/㎥). The SiC II exhibited higher values of temperature difference normalized by irradiance due to the effect of additional solar heat absorption and heat transfer to the gas by the particles entrained in the freeboard region in addition to the efficient thermal diffusion of the solar heat received at bed surface. Heat absorption rate and efficiency increased with increasing the gas velocity and fluidization number. The SiC II showed maximum heat absorption rate of 17.8 W and thermal efficiency of 14.8%, which are about 33% higher than those of SiC I within the experimental gas velocity range.

• Journal of Bio-Environment Control
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• v.10 no.3
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• pp.141-147
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• 2001

To compare to the optical and physical properties of covering materials for plastic greenhouse, EVA(ethylene vinyl acetate, 0.08 mm), polyorefine antifog (0.1 mm), fluoric (0.06 mm), diffused (0.15 mm), polyorefine antidrop (0.15 mm) and PET (polyethylene terephthalate, 0.5 mm) films were used. The small greenhouse (5.4$\times$18.5$\times$2.9 m, W$\times$L$\times$H) investigated during 3 years form 1997 to 1999. After covering materials were used for greenhouse covering during 30 months, UV (300-400 nm) transmittances of diffused film and PET were appeared from 25 to 26%, while those of fluoric film and the other films were 76% and from 63 to 67%. For PAR (photosynthetically active radiation, 400-700 nm), the transmittances of fluoric, antidrop, PET, antifog, EVA, and diffused film were 86.5%, 80.5%, 76.3%, 75.5%, 74.1% and 61.9% respectively. The losses of PAR transmittance of EVA and the antidrop film during period between 7 days and 30 months were higher value 12% and lower value 6% than any other film. Under the canopy of tomato plants, light intensities of the diffused film and the antifog film were 2.5 times and 1.4 times higher than those of PET. Tensile resistances of fluoric film at the break point were the higher than those of antifog film and diffused film. While impact resistance of the antidrop film was the highest value, but the fluoric film was the lowest. Air temperature inside the greenhouse for the day showed to be changed the similar light transmittance of the films. But the increasing order of air temperature for the night was PET, fluoric, antidrop, diffused, antifog and EVA film. Especially, air temperature in the PET was 4$^{\circ}C$ higher than that in the EVA. Solar radiations of the fluoric film, the antidrop film, PET and antifog film in the greenhouse were 32%, 15%, 11% and 4% higher than those of PET. However, those of the diffused film was 7% less than PET.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.286-292
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• 2019

This study aimed to investigate the suitable of layer on growth of six baby leaf vegetables using existing facilities and equipment in rice seedling nursery. Three kinds of Lactuca(lettuce 'Jinppallola' and 'Romain white', and indian lettuce), two of Brassica(tatsoi and red tatsoi) and amaranth were used as the materials. After sowing, the rice seedling tray was placed in multi bench system($L120{\times}W60{\times}H195cm$, 10th floor), which were low(1st) layer above 15cm, middle(4th) layer above 115cm and high(7th) layer above 175cm apart from ground. Irrigation was sprayed 2~3 times a day using a automatic irrigation system. The growth characteristics and leaf color were investigated when leaf vegetables were reached the optimum size(within 10cm of plant height). During the culture periods(29th Jun.~31th Jul. 2017), daytime average temperature was $27.4{\sim}28.3^{\circ}C$ regardless of layers but solar irradiance was higher in the high-layer than low and middle-layer of 37% and 22%, respectively. The leaf length, leaf width and number of leaves in middle and high-layer have a tendency to increase but, fresh weight was different according to the layer. When the correlation between accumulation radiation and growth was analyzed, all of growth factor of Amaranth showed a high correlation and other cultivars showed correlation with each growth factors. As a result, It is suitable that amaranth and red tatsoi for high-layer, Indian lettuce and tatsoi for middle and high-layer and 'Romain white' for middle-layer. The growth of red lettuce 'Jinppallola' was good at low layer, but leaf color expression was poor. So the high layer is suitable for 'Jinppallola'.

• Journal of Bio-Environment Control
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• v.32 no.2
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• pp.157-164
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• 2023

Codonopsis lanceolata (S. et Z.) Trautv. is mainly cultivated in Korea and China as a medicinal crop. C. lanceolata is difficult to produce plug seedlings in the summer, because C. lanceolata has a low germination rate and is vulnerable to high temperatures. Cold treatment is effective in breaking dormancy of seeds and increasing the germination rate. Shading cultivation can control the solar irradiance received by plants and reduce the damage by high temperatures and strong light. This study was conducted to examine the appropriate cold treatment period for the improving germination of C. lanceolata, and shading level during the summer seedling period. Cold treatment experiments were conducted for 0 (control), 1, 2, 3, and 4 weeks at 4℃ before sowing. In the shading experiment, C. lanceolata was grown for 45 days with 0 (non-treatment), 45, 75% shading levels. Cold treatment for one week significantly improved the germination energy. The plant height, leaf area, and fresh and dry weights of C. lanceolata seedlings were significantly increased under the 45% shading level. Total root length, root surface area, and the number of root tips were significantly higher in shading treatment (45 and 75%) than in non-treatment. The C. lanceolata seedling's compactness and Dickson's quality index were the highest at 45% shading level. Therefore, these results recommended sowing C. lanceolata after cold treatment for one week at 4℃, and 45% shading level could stably culture C. lanceolata plug seedlings during the high temperature period.

• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.251-262
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• 2010

In order to provide quantitative control of the standard products of Geostationary Ocean Color Imager (GOCI), on-board radiometric correction, atmospheric correction, and bio-optical algorithm are obtained continuously by comprehensive and consistent calibration and validation procedures. The calibration/validation for radiometric, atmospheric, and bio-optical data of GOCI uses temperature, salinity, ocean optics, fluorescence, and turbidity data sets from buoy and platform systems, and periodic oceanic environmental data. For calibration and validation of GOCI, we compared radiometric data between in-situ measurement and HyperSAS data installed in the Ieodo ocean research station, and between HyperSAS and SeaWiFS radiance. HyperSAS data were slightly different in in-situ radiance and irradiance, but they did not have spectral shift in absorption bands. Although all radiance bands measured between HyperSAS and SeaWiFS had an average 25% error, the 11% absolute error was relatively lower when atmospheric correction bands were omitted. This error is related to the SeaWiFS standard atmospheric correction process. We have to consider and improve this error rate for calibration and validation of GOCI. A reference target site around Dokdo Island was used for studying calibration and validation of GOCI. In-situ ocean- and bio-optical data were collected during August and October, 2009. Reflectance spectra around Dokdo Island showed optical characteristic of Case-1 Water. Absorption spectra of chlorophyll, suspended matter, and dissolved organic matter also showed their spectral characteristics. MODIS Aqua-derived chlorophyll-a concentration was well correlated with in-situ fluorometer value, which installed in Dokdo buoy. As we strive to solv the problems of radiometric, atmospheric, and bio-optical correction, it is important to be able to progress and improve the future quality of calibration and validation of GOCI.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.535-543
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• 2022

A CPFD (Computational particle fluid dynamics) model of solar fluidized bed receiver of silicon carbide (SiC: average d_p=123 ㎛) particles was established, and the model was verified by comparing the simulation and experimental results to analyze the effect of particle behavior on the performance of the receiver. The relationship between the heat-absorbing performance and the particles behavior in the receiver was analyzed by simulating their behavior near bed surface, which is difficult to access experimentally. The CPFD simulation results showed good agreement with the experimental values on the solids holdup and its standard deviation under experimental condition in bed and freeboard regions. The local solid holdups near the bed surface, where particles primarily absorb solar heat energy and transfer it to the inside of the bed, showed a non-uniform distribution with a relatively low value at the center related with the bubble behavior in the bed. The local solid holdup increased the axial and radial non-uniformity in the freeboard region with the gas velocity, which explains well that the increase in the RSD (Relative standard deviation) of pressure drop across the freeboard region is responsible for the loss of solar energy reflected by the entrained particles in the particle receiver. The simulation results of local gas and particle velocities with gas velocity confirmed that the local particle behavior in the fluidized bed are closely related to the bubble behavior characterized by the properties of the Geldart B particles. The temperature difference of the fluidizing gas passing through the receiver per irradiance (∆T/I_DNI) was highly correlated with the RSD of the pressure drop across the bed surface and the freeboard regions. The CPFD simulation results can be used to improve the performance of the particle receiver through local particle behavior analysis.