• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.717-721
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• 2011

In case of plastic film greenhouses cultivating fresh vegetables on paddy soil, soil characteristics must be considered as more important factor than any other factors. Generally after the four years of cultivation, soils tend to increase electrical conductivity value, nutrient unbalance and soil pests. As a result, degradation of agricultural products occurred, therefore it is necessary to improve soil conditions. In this study, yield and economic cost of cucumber were analyzed. The best soil conditions for cucumber cultivation were alluvial or valley in soil topology, moderately or poorly drainage in soil drainage classes, coarse loamy soil in texture. In addition, rich-sunlight and-deep groundwater would be proper for the cucumber cultivation. Good environmental managements of plastic film greenhouse were as follows. The temperature needed to be adjusted three times. The optimal daytime temperature could be $22{\sim}28^{\circ}C$, the one from 12 until night could be $14{\sim}15^{\circ}C$, and the temperature from 24 to sunrise could be $10{\sim}12^{\circ}C$. During plant growth period, soil moisture content was as low as 10~15%, and it needed to be maintained as 15~20% during reproductive growth period. To control pests, catch crop cultivation and solar treatment were carried out, after those EC was reduced and the root-knot nematode was controled too. Cucumber yield from the plot with improved soil managements increased to $158.4Mg\;ha^{-1}$, but plot with successive cropping injury yielded $140.3Mg\;ha^{-1}$. The income from the plot with improved soil managements was 215,676 thousand won $ha^{-1}$, the plot with successive cropping injury was 131,649 thousand won $ha^{-1}$. Income rate of each plot was 51.8% and 38.4%, respectively.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.26-67
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• 2020

Synthetic Aperture Radar(SAR) is able to photograph the earth's surface regardless of weather conditions, day and night. Because of its possibility to search for hydrological factors such as soil moisture and groundwater, and its importance is gradually increasing in the field of water resources. SAR began to be mounted on satellites in the 1970s, and about 15 or more satellites were launched as of 2020, which around 10 satellites will be launched within the next 5 years. Recently, various types of SAR technologies such as enhancement of observation width and resolution, multiple polarization and multiple frequencies, and diversification of observation angles were being developed and utilized. In this paper, a brief history of the SAR system, as well as studies for estimating soil moisture and hydrological components were investigated. Up to now hydrological components that can be estimated using SAR satellites include soil moisture, subsurface groundwater discharge, precipitation, snow cover area, leaf area index(LAI), and normalized difference vegetation index(NDVI) and among them, soil moisture is being studied in 17 countries in South Korea, North America, Europe, and India by using the physical model, the IEM(Integral Equation Model) and the artificial intelligence-based ANN(Artificial Neural Network). RADARSAT-1, ENVISAT, ASAR, and ERS-1/2 were the most widely used satellite, but the operation has ended, and utilization of RADARSAT-2, Sentinel-1, and SMAP, which are currently in operation, is gradually increasing. Since Korea is developing a medium-sized satellite for water resources and water disasters equipped with C-band SAR with the goal of launching in 2025, various hydrological components estimation researches using SAR are expected to be active.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.2
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• pp.109-116
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• 1979

This experiment was conducted to find out the effects on soybean plant exposed with various concentration and different fumigation periods of ammonia gas ($0.2mg/{\ell}$). The yield of soybean, nitrogen and, chlorophyll contents in leaves, and percentage of destroyed leaf area were investigated. The results were summarized as: 1. The soybean yield losses and percentage of destroyed leaf area were positively correlated with concentration of inflicting ammonia gas respectively. The yield losses was higher at noon exposure time than at night exposure time. 2. The soybean yield was negatively correlated with the percentage of destroyed leaf area. 3. The highest percentage of destroyed leaf area had at afternoon exposure time (14:00-15:00 o'clock) by $0.2mg/{\ell}$ ammonia gas fumigation, and the lowest one had at midnight exposure time (22:00-23:00 o'clock). 4. According to the increasing concentration of ammonia gas, the total and water soluble nitrogen contents in soybean leaves were increased, but the contents of chlorphyll b on decreasing rate. 5. The nitrogen contents in plant were higher in the afternoon exposure than in the morning, but the contents of chlorophyll were higher at night time exposure than at day time. 6. The highest decreasing of absorption spectra of chlorohpyll in chloroplast had at 10:00-11:00 o'clock on fumigation time and the lowest one had at 22:00-23:00 o'clock.

• Microbiology and Biotechnology Letters
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• v.38 no.3
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• pp.308-314
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• 2010

This study was conducted to investigate the characteristics and concentrations of ammonia produced from the livestock swine nightsoil treated with or without the livestock - environment improving agents. Odor generating device made of acryl was made by volume of 96 L to sample the ammonia odor. When swine night soil was placed in the device, concentration of ammonia averaged out at about 23.4 ppmv and ranged from 16 ppmv to 40 ppmv. Removal efficiencies of them showed 50% to 90% as compared to initial level before spraying, when the spray type agents were used immediately after they purchased. The persistence of the efficiency was retained for first two days. Among the agents, the natural deodorant showed the best efficiency of 87 to 99%. To evaluate the effects of 5 kinds of dietary probiotic powders, the experiments were conducted and based dietary treatments without antibiotics on growing piglets. In experiments, 60 piglets ($6.3{\pm}0.2\;kg$) were subjected to a 35-day feeding trial in which the effects of the dietary probiotic powder on the ammonia emission were compared. The ammonia gas emission was measured for every week. Ammonia emission from the swine nightsoil obtained from piglets supplemented with the probiotics power was lower than that of the nightsoil obtained from pigs in the control treatment (without probiotics). In ammonia removal efficiencies of the experimental groups, some products showed from 71% to 99% removal efficiencies throughout the entire period as compared to the control group. On the other hand, initial reduction of ammonia in some product was effective temporarily. After then, it did not show any reduction efficiency of ammonia.

• Magazine of the Korean Society of Agricultural Engineers
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• v.19 no.1
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• pp.4312-4322
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• 1977

In order to investigate the effect of the water content and the accelerated curing on the strength of the soil-cement mixtures, laboratory test of soil cement mixtures was performed at five levels of water content, four levels of accelerated curing temperatures, three levels of normal curing periods, and six levels of accelerated curing time. Also this study was carried out to investigate the effect of grain size distribution of 21 types of soils on the strength of soil-cement mixtures at four levels of cement content and three levels of curing time. The results are summarized as follows: 1. Optimum moisture content increased with increase of the cement content, but maximum dry density was changed ununiformly with cement content. Water content corresponding to the maximum strength was a little higher than the optimum moisture content along the increase of cement content. 2. In molding the specimens with the optimum moisture content, the maximum strength appeared at the wet side of the optimum moisture content. 3. According to increase of curing temperature as 30, 40, 50, and 60$^{\circ}C$, unconiiend compressive strength of soil-cement mixtures increased, the rate of increase at the early curing period was large, and approximately 120 hours was suifficient to harden soil-cement mixtures completely. 4. The strength of soil-cement mixtures at the curing temperature of 10$^{\circ}C$ decreased at the rate of 30 to 50 percent than at the curing temperature of 20$^{\circ}C$, and the strength of soil-cement mixtures at the curing temperature of 0$^{\circ}C$ increased a little with increase of curing time. 5. Although the strength of soil-cement mixtures seemed to be a little affected by the temperature difference between day time and night, it was recommended that reasonable working period was the duration from July to August of which average maximum temperature of Korea was approximately 30$^{\circ}C$. 6. Accelerated curing time corresponding to the normal curing time of 28-day was shorten with increase of curing temperature, also it was a little affected by the cement. Accelerated curing time that the strength of soil-cement mixtures for the cement of 9 percent and the curing temperature of 60was shorten with increase of curing temperature, also it was a little affected by the cement. Accelerated curing time that the strength of soil-cement mix- tures for the cement of 9 percent and the curing temperature of 60$^{\circ}C$ was 45 hours at the KY sample, 50 hours at the MH, 40 hours at the SS, and 34 hours at the JJ respectively. 7. Accelerated curing time was depended upon the grain size distribution of soil, it decreased with increase the percent passing of No. 200 sieve. 8. Relationship between the normal curing times and the accelerated curing times showed that there was a linear relationship between them, its slope decreased with increase of curing temperature. 9. The most reasonable soil of the soil-cement mixtures was the sandy loam which was a well graded soil. Assuming the base of road requiring 7-day strength of 21 kg/$\textrm{cm}^2$ being used, the soil-cement mixtures could be obtained with adding 6 percent of cement in such a sails S-7, S-8, S-9, S-10, S-11, S-12, S-13. 10. The regression equation between the 28-day and the 7-day strength was obtained as follow; q28=1.12q7,+6.5(r=0.96).

• Journal of Korean Society of Forest Science
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• v.94 no.6
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• pp.496-503
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• 2005

This study was conducted to investigate the influences of sapflow flux on soil water tensions and soil moisture content at the Abies holophylla plots in Gwangneung, Gyeonggido, from September to October 2004. The Abies holophylla had been planted in 1976 and thinning and pruning were carried out in 1996 and 2004. Sapflow flux was measured by the heat pulse method, and soil water tension was measured by tensiometer at hillslope and streamside. Time domain reflectometry probes (TDR) were positioned horizontally at the depth of 10, 30 and 50 cm to measure soil moisture content. All of data were recorded every 30 minutes with the dataloggers. The sapflow flux responded sensitively to rainfall, so little sapflow was detected in rainy days. The average daily sapflow flux of sample trees was 10.16l, a maximum was 15.09l, and a minimum was 0.0l. The sapflow flux's diurnal changes showed that sapflow flux increased from 9 am and up to 0.74 l/30 min. The highest sapflow flux maintained by 3 pm and decreased almost 0.0 l/30 mm after 7 pm. The average soil water tensions were low ($-141.3cmH_2O$, $-52.9cmH_2O$ and $-134.2cmH_2O$) at hillslope and high ($-6.1cmH_2O$, $-18.0cmH_2O$ and $-3.7cmH_2O$) at streamside. When the soil moisture content decreased after rainfall, the soil water tension at hillslope responded sensitively to the sapflow flux. The soil water tension decreased as the sapflow flux increased during the day time, whereas increased during the night time when the sapflow flux was not detected. On the other hand, there was no significant relationship between soil water tension and sapflow flux at streamside. Soil moisture content at hillslope decreased continuously after rain, and showed a negative correlation to sapflow flux like a soil water tension at hillslope. As considered results above, it was confirmed that the response of soil moisture tension to sapflow flux at hillslope and streamside were different.

• Journal of Bio-Environment Control
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• v.10 no.4
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• pp.237-243
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• 2001

The experiment was conducted to investigate the effect of different mulching materials on the growth and quality of oriental melon in protected cultivation. Soil temperature, plant growth and fruit quality were affected by different mulching materials, clear polyethylene (P.E.) film (control), clear inset between black P.E. film, green P.E. film. and recycled ethylene vinyl acetate (E.V.A.) film. The highest night soil temperature was at 20 cm depth under green P.E. film, but was at 5 cm depth under other materials. Difference of soil temperature as affected by mulching materials decreased with increasing soil depth. Plant height, number of nodes, leaf area index (LAI), crop growth rate (CGR), and relative growth rate (RGR) at 30 days after transplanting were significantly greater in the recycled E.V.A. film treatment than in the other treatments. Fresh weight of weeds growth under the mulching materials was not affected by mulching material at 30 days after transplanting. However, it was the greatest under clear P.E. film mulching at 90 days after transplanting. Harvesting time of recycled E.V.A. film was 2 days earlier than that of clear P.E. film. Difference in fruit weight and length, and soluble solid content were not affected by the mulching materials. Marketable yield was 2,426 kg.10a$^{-1}$ in recycled E.V.A. film treatment, which was 6% greater than in clear P.E. film treatment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.2
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• pp.327-333
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• 2019

For sustainable lunar exploration, the most required resources should be procured on site because it takes tremendous cost to transfer the resources from the Earth to the Moon. The technologies required for use of lunar resources refers to In-Situ Resource Utilization (ISRU). As the ISRU technology cannot be verified in the Earth, a lunar surface environment simulator is necessary to be prepared in advance. The Moon has no atmosphere, and the average temperature of the lunar surface reaches to $107^{\circ}C$ during the daytime and $-153^{\circ}C$ at night. The lunar surface is also covered with very fine soils with sharp particles that are electrostatically charged by solar radiation and solar wind. In this research, generation of vacuum environment with lunar soil mass in a chamber and simulation of electrostatically charged soils are taken into consideration. It was successful to make a vacuum environment of a chamber including lunar soils without soil disturbance by controlling evacuation rate of a vacuum chamber. And an experiment procedure for simulating the charged lunar soil was suggested by theoretical consideration in charging phenomena on lunar dust.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.5
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• pp.597-603
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• 1997

Orostachys japonicus, Wasong as herb medicine, has been artificially cultivated as an anti-tumor medicinal. The experiment was carried out to examine the effect of natural daylength as control or night-break treatment (NB) imposed at June 20, July 18 or Aug. 15 on its growth, dry weights of leaf and bract, stem, floret and root, and morphological characters including bolting and floret flowering. After a plant was grown in a 15cm plastic pot containing a 2 : 1 soil : peat moss mixture on May 23, three treatments with above differing night-break had been imposed around midnight up to Nov. 7. The plants were sampled 3 times at the same day forced to night-break and then done 6 times by 2-week interval after the final NB. Plant height and inflorescence length of all the NB increased with delayed NB but declined in comparison with the natural daylength. No. of leaves including bracts showed similar response to plant height although NB given before July 18 showed less leaves and bracts. Stem diameters of NB were continuously increased to middle Sept. to middle Oct. while that of natural daylength decreased after middle Oct. Natural daylength or NB given on Aug. 15 had greater fraction, shoot and total dry weights resulting from increment of leaf and bract up to Aug. or of floret, stem and root after Sept. The earlier NB, the later formation of florets and the less number of flowering florets whereas in natural daylength florets on inflorescence begun to be formed from middle Sept. were sharply increased up to middle Oct. when all the plants were flowered. Bolting was not formed in the plant of the earliest NB of June 20, and thereby no anthesis of florets up to early Nov. It was concluded that year-round cultivation of Orostachys japonicus plants was possible through controlling the NB timing because its bolting and flowering of florets separately occurred.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.357-360
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• 1997

To fine out the concentration of $SO_2$ gas in plastic film house, the survey was conducted at 343 sites throughout the nation. The $SO_2$ concentration in plastic film house were similar both heating and non-heating, but $SO_2$ cocentration higher than 0.8ppm was detected at those with heating. The $SO_2$ concentration in plastic film house cultivated red-pepper higher than those of cucumber or tomato cultivation, and it was produced higher amounts at day time than night due to the higher temperature. In plastic film house with heating, $SO_2$ was leaked at brocken parts of heater and joint of stove pipe, sometimes, $SO_2$ discharged from smokestack was resucked with air. $SO_2$ concentration in the plastic film house with and without ventilation were 0.2 and 0.6ppm, respectively.