• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.1022-1026
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• 2012

To evaluate the application level of expeller cake fertilizer (ECF), we have investigated soil chemical properties, leaf mineral contents and yield of red mustard in plastic film greenhouse. Four levels of fertilizer were applied as 50% (ECF 50), 75% (ECF 75), 100% (ECF 100) and 150% (ECF 150) by base $1,848kg\;kg^{-1}$ of ECF. In 2010, red mustard was planted on April 28 in silt loam soil and harvested on July 7. Commerical yields were measured 12 times from May 14 to July 7. Electrical conductivity ($3.40{\sim}3.54dS\;m^{-1}$), available $P_2O_5$ ($580{\sim}618mg\;kg^{-1}$) and exchangeable cations ($K^+$, $Ca^{2+}$ and $Mg^{2+}$) were tended to increase by the application of ECF. However, the range of those was not so big increasing amount. The content of T-N, K, Ca and P of red mustard leaves was $63.2{\sim}66.4g\;kg^{-1}$, $55.1{\sim}56.4g\;kg^{-1}$, $8.6{\sim}9.5g\;kg^{-1}$ and $5.7{\sim}6.3g\;kg^{-1}$, respectively. The nitrogen utilization rate of red mustard was 38~52%, and it was decreased with increased application of ECF. The yield of red mustard was 13,670 to $14,460kg\;ha^{-1}$ on the basis of application amount of ECF and the yield did not increased in spite of increased ECF. The optimum dose of application of ECF for cultivation of red mustard was from $924kg\;ha^{-1}$ (ECF 50) to $1,386kg\;ha^{-1}$ (ECF 75). Environment-friendly and economical amount of applied fertilizer is more important than yield for cultivation of red mustard.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.160-165
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• 2010

To reduce the dose of fertilizers is very important to sustainable production of many horticultural crops, including strawberry. In order to practice the environment friendly agriculture of strawberry cultivation in plastic film house, soil chemical properties of 435 soil samples (232 for loam, 83 for sandy loam, and 120 for silt loam) in Chungnam Province from2008 to 2009 were determined. The average of pH, EC, OM, Av. $P_2O_5$, Ex. $K^+$, Ex. $Ca^{2+}$, Ex. $Mg^{2+}$, and Ex. $Na^+$ was 6.5, 2.28 dS $m^{-1}$, 26 g $kg^{-1}$, 910 mg $kg^{-1}$, 1.09 $cmol_c\;kg^{-1}$, 8.3 $cmol_c\;kg^{-1}$, 2.5 $cmol_c\;kg^{-1}$, and 0.58 $cmol_c\;kg^{-1}$, respectively. The content of Av. $P_2O_5$ in sandy loam soil was significantly higher than silt loam soil, whereas other properties showed no difference between soil texture. The kinds of strawberry cultivars showed no difference in soil chemical properties. The frequency distribution within optimum range of soil chemical properties was 30.6%, 35.4%, 37.0%, 5.3%, 8.5%, 8.5%, and 17.9% for pH, EC, OM, Av. $P_2O_5$, Ex. $K^+$, Ex. $Ca^{2+}$, and Ex. $Mg^{2+}$, respectively. Especially, excessive portion of Av. $P_2O_5$, and Ex. $Ca^{2+}$ were high 86.9%, and 86.0%, respectively. EC values of soil samples were significantly positive correlatoin with all chemical properties except soil pH. In principle component analysis of chemical properties in soil samples, the percentage of variance explained by PC 1 was 38.8%, while PC 2 explained 17.8%of the variance, for a cumulative total of 56.6%. These results were able to distinguish between soil textures and strawberry cultivars. Also, these results considered that understanding of soil chemical properties under using principal component analysis be able to improve amounts of fertilizers for sustainable agriculture in plastic film house.

• Korean Journal of Food Science and Technology
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• v.32 no.4
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• pp.755-762
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• 2000

Physicochemical properties of commercial sweet potato starches manufactured by 7 different companies were investigated in comparison with corn and potato starches. Crude ash and protein content varied from 0.36 to 1.02%, and from 0.04 to 0.14% based on dry weight, respectively. The protein contents were relatively smaller than that of corn or potato starch. But whiteness of the sweet potato starches was less than that of corn or potato starch. Mean diameter of the sweet potato starch granules varied from 14.23 to $21.08\;{\mu}m$ depending on the company and all sweet potato starches showed bimodal size distributions. Pasting viscosity measured by Rapid Viscoanalyzer(RVA) also showed variations among the starches of different companies. The starch from D company in Korea had the lowest pasting temperature$(74.00^{\circ}C)$ whereas the starch from a phillippine company(P) did the highest one$(80.35^{\circ}C)$. The peak viscosity of sweet potato starches was higher than that of corn starch but lower than that of potato starch. The D company starch also showed the highest peak viscosity(2283 cp) among the starches tested. Paste breakdown by hot shearing ranged from 524 cp (S company) to 1279 cp (HL company). Textural properties of the starch gels appeared significantly different among the starches of different manufacturers. The greatest hardness of the gel was $137.90\;g_{f}$ at 1 day storage whereas the lowest value was $31.53\;g_{f}$. Except the starches from 2 companies (P and S), the sweet potato starches formed very soft and weak gels. P or S company starches formed the gels similar to potato starch. Syneresis by freeze-thawing treatments appeared less for sweet potato starch gels than that for corn starch gels, but greater than that for potato starch gel. The overall properties of the sweet potato starches varied by the manufacturing companies, and ranged between those of corn and potato starches.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.4
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• pp.77-83
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• 2016

The objectives of this study was to investigate the difference between organic-farming and conventional-farming soils relatives to soil chemical properties and microbial flora. Fifteen soil sampling sites were chosen from the certified organic upland farm, considered with its location, crop and application of organic compost types. Soil chemical properties were analyzed by standard methods established by National Institute of Agricultural Sciences, Rural Development Administration. For the soil chemical properties, the values of pH were ranged from 4.5 to 7.3. The values of electrical conductivity (EC) in the sampling sites were below 2 dS/m of convention cultivation soil. For analyzing the microbial flora, the bacillus(16S rDNA) and cladothricosis(18S rDNA) were analyzed by using PCR-DGGE (Denaturing Gradient Gel Electrophoresis) in the soil of 15 sampling sites. Cluster analysis of biodiversity index was performed by using pattern of DGGE. DGGE patterns and clustering analysis of bacterial DNA from soil extracts revealed that the bacterial community was differentiated between less than 5 years and more than 5 years depending on the cultivation history. But there was no consistent tendency between cultivation history and regional trend in the case of molds. Therefore, it would be very effective to analyze bacterial clusters of organically cultivated soils in long - term cultivated soil for more than 5 years.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.415-423
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• 2010

Pore network models are useful tools to investigate soil pore geometry. These models provide quantitative information of pore geometry from 3D images. This study presents a pore network model to quantify pore structure and hydraulic characteristics. The objectives of this work were to apply the pore network model to characterize pore structure from large images to quantify pore structure, calculate water retention and hydraulic conductivity properties from a three dimensional soil image, and to combine measured hydraulic properties from experiments with calculated hydraulic properties from image. Soil samples were taken from a site located at the Baltimore science center, which is located inside of the city. Undisturbed columns were taken from the site and scanned with a computer tomographer at resolutions of 22 ${\mu}m$. Pore networks were extracted by medial-axis transformation and were used to measure pore geometry from one of the scanned samples. Water retention and unsaturated hydraulic conductivity values were calculated from the soil image. Properties of soil bulk density, water retention and unsaturated hydraulic conductivity were measured from three replicates of scanned soil samples. 3D image analysis provided accurate detailed pore properties such as individual pore volumes, pore length, and tortuosity of all pores. These data made possible to calculate accurate estimations of water retention and hydraulic conductivity. Combination of the calculated and measured hydraulic properties gave more accurate information on pore sizes over wider range than measured or calculated data alone. We could conclude that the hydraulic property computed from soil images and laboratory measurements can describe a full structure of intra- and inter-aggregate pores in soil.

• The Journal of the Acoustical Society of Korea
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• v.20 no.2E
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• pp.30-45
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• 2001

This study considers the environmental factors affecting propagation loss and sonar performance in the continental regions of the East Coast Sea of Korea. Water mass distributions appear to change dramatically in a few weeks. Simple calculation with the case when the NKCW (North Korean Cold Water) develops shows that the difference in propagation loss may reach in the worst up to 10dB over range 5km. Another factor, an eddy, has typical dimensions of 100-200km in diameter and 150-200m in thickness. Employing a typical eddy and assuming frequency to be 100Hz, its effects on propagation loss appear to make lower the normal formation of convergence zones with which sonars are possible to detect long-range targets. The change of convergence zones may result in 10dB difference in received signals in a given depth. Thermal fronts also appear to be critical restrictions to operating sonars in shallow waters. Assuming frequency to be 200Hz, thermal fronts can make 10dB difference in propagation loss between with and without them over range 20km. An observation made in one site in the East Coast Sea of Korea reveals that internal waves may appear in near-inertial period and their spectra may exist in periods 2-17min. A simulation employing simple internal wave packets gives that they break convergence zones on the bottom, causing the performance degradation of FOM as much as 4dB in frequency 1kHz. An acoustic experiment, using fixed source and receiver at the same site, shows that the received signals fluctuate tremendously with time reaching up to 6.5dB in frequencies 1kHz or less. Ambient noises give negative effects directly on sonar performance. Measurements at some sites in the East Coast Sea of Korea suggest that the noise levels greatly fluctuate with time, for example noon and early morning, mainly due to ship traffics. The average difference in a day may reach 10dB in frequency 200Hz. Another experiment using an array of hydrophones gives that the spectrum levels of ambient noises are highly directional, their difference being as large as 10dB with vertical or horizontal angles. This fact strongly implies that we should obtain in-situ information of noise levels to estimate reasonable sonar performance. As one of non-stationary noise sources, an eel may give serious problems to sonar operation on or under the sea bottoms. Observed eel noises in a pier of water depth 14m appear to have duration time of about 0.4 seconds and frequency ranges of 0.2-2.8kHz. The 'song'of an eel increases ambient noise levels to average 2.16dB in the frequencies concerned, being large enough to degrade detection performance of the sonars on or below sediments. An experiment using hydrophones in water and sediment gives that sensitivity drops of 3-4dB are expected for the hydrophones laid in sediment at frequencies of 0.5-1.5kHz. The SNR difference between in water and in sediment, however, shows large fluctuations rather than stable patterns with the source-receiver ranges.

• Journal of the Korean Magnetics Society
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• v.17 no.2
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• pp.81-85
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• 2007

MnTe layers of high crystalline quality were successfully grown on Si(100) : B and Si(111) substrates by molecular beam epitaxy (MBE). Under tellurium-rich condition and the substrate temperature around $400^{\circ}C$, a layer thickness of $700{\AA}$ could be easily obtained with the growth rate of $1.1 {\AA}/s$. We investigated the structural, magnetic and transport properties of MnTe layers by using x-ray diffraction (XRD), superconducting quantum interference device (SQUID) magnetometry, and physical properties measurement system (PPMS). Characterization of MnTe layers on Si(100) : B and Si(111) substrates by XRD revealed a hexagonal structure of polycrystals with lattice parameters, ${\alpha}=4.143{\pm}0.001{\AA}\;and\;c=6.707{\pm}0.001{\AA}$. Investigation of magnetic and transport properties of MnTe films showed anomalies unlike antiferromagnetic powder MnTe. The temperature dependence of the magnetization data taken in zero-field-tooling (ZFC) and field-cooling (FC) conditions indicates three magnetic transitions at around 21, 49, and 210 K as well as the great irreversibility between ZFC and FC magnetization in the films. These anomalies are attributable to a magnetic-elastic coupling in the films. Magnetization measurements indicate ferromagnetic behaviour with hysteresis loops at 5 and 300 K for MnTe polycrystalline film. The coercivity ($H_c$) values at 5 and 300 K are 55 and 44 Oe, respectively. In electro-transport measurements, the temperature dependence of resistivity revealed a noticeable semiconducting behaviours and showed conduction via Mott variable range hopping at low temperatures.

• Journal of the Korea Concrete Institute
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• v.16 no.1 s.79
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• pp.79-87
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• 2004

The qualify of lightweight aggregate made from waste PET bottle(WPLA) and the workability, the unit weight and strength property of concrete with WPLA were investigated for the purpose of recycling the waste PET bottles as lightweight concrete fine aggregate. This study indicated a good result that WPLA should be replaced with less than $50\%$ of natural fine aggregate. When WPLA was replaced with $50\%$ of natural fine aggregate, the specific gravity and water absorption of mixed fine aggregate were greatly reduced about 23 and $75\%$ respectively in comparison with those of river sand. The quality of WPLA affected on the properties of lightweight aggregate concrete. The workability of fresh concrete with WPLA(WPLAC) was improved with increasing the replacement ratio of WPLA and water cement ratio. Slump increasing ratio of the former showed about $45 {\~} 120\%$ because that a specific gravity of fine aggregate was decreased from 2.6 to 1.7. The unit weight of concrete with $75\%$ WPLA was decreased about $17\%$ in comparison with that of control concrete. Furthermore, the compressive strength of concrete with 25 and $50 \%$ WPLA at the age of 28 days increased higher than 30 MPa regardless with water cement ratio (W/C=45, 49 and $53\%$) of this study. Specific strength of concrete with $25\%$ WPLA, $15.11{\times}10^3 MPa{\cdot}m^3/kg$, was higher than that of contro concrete in water cement ratio of $49\%$. The compressive strength-splitting tensile strength ratio and compressive strength-modulus of elasticity ratio of WPLAC were similar to that of nomal lightweight aggregate concrete. This results showed a good estimation that WPLA will be able to recycled as a fine aggregate for lightweight concrete.

• Journal of Bio-Environment Control
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• v.4 no.1
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• pp.59-67
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• 1995

This study was conducted to develope the automatic insulation system which control inside temperature of the greenhouse. For this purpose, the double- wall greenhouse and system which could automatically supply and discharge styrene pellets were constructed and abrasion of the pellets, blower ability, insulating property, transmittance and shading effect were analyzed by the experiments. The results obtained from this study can be summarized as follows : 1. It took an hour and fifteen minutes to supply and discharge about 2㎥ pellets in the experimental greenhouse. However, it is possible to reduce the operation time by proper selection of the blower and exhaust port, and by proper control of the supply and return pipe. 2. It was founded that the indirect delivery way was more profitable than the direct one in the supply and return of pellets. 3. When the transmittance was measured between 10 a.m. and 3 p.m., the average light transmissivity rate was 67%. 4. In winter nighttime, the inside temperature of the double- wall greenhouse with out the pellets was higher than the outside temperature by 3.4$^{\circ}C$ on an average. However, the inside temperature of the double - wall greenhouse with insulated area 73% was higher than the outside by one 6.6$^{\circ}C$ on an average, and the inside temperature of the greenhouse with insulated area 100% was higher than outside one by 13.5$^{\circ}C$ on an average. Therefore, it was proved that the insulating ability of the double - wall greenhouse in nighttime was excellent. 5. When the outside temperature was 36.9$^{\circ}C$ on an average, the inside temperature of the double- wail greenhouse with insulated area 100% was 3$0^{\circ}C$ on an average. As the inside temperature was lower than the outside one by 7$^{\circ}C$ on an average, we could know that the shading effects of the double- wall greenhouse were excellent in summer daytime.

• Progress in Medical Physics
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• v.20 no.3
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• pp.139-144
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• 2009

Recently, the mathematical analysis of stent simulation has been improved, with the help of development of various tool which measure mechanical property and location of stent in artery. The most crucial part of the stent modeling is how to design ideal stent and to evaluate the interaction between stent and artery. While there has been great deal of researches on the evaluation of the expansion, stress distribution, deformation of the stent in terms of the various parameters, few verification through computer simulation has been performed about deformation and stress distribution of the stent. In this study, we have produced the corresponding results between experimental test using Universal Testing Machine and computer simulation for the ideal model of stent. Also, we have analyzed and compared stress distribution of stent in the cases of that with membrane and that without membrane. The results of this study would provide minimum change of plan and good quality for ideal stent replacing damaged artery through the analysis using computer simulation in the early stage of stent design.