• Korean Journal of Soil Science and Fertilizer
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• v.34 no.1
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• pp.71-75
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• 2001

Linear regression analyses between the electrical conductivity of the saturation-paste extract. ECe, and the electrical conductivity of the 1:5 soil extract, EC1:5, for different soils yielded different dilution factors, or slopes with significant $r^2$ values from 0.842 to 0.905. The dilution factor was inversely proportional to the cation exchange capacity of soil which reflected textural difference. The dilution factors recommended for different textural classes ranged from 6.44 for clay soil to 12.29 for sandy soil based on the CEC's of the textural classes among 350 surface soils recorded in the Taxonomical Classification of Korean Soils except volcanic ash derived soils. Though saturation percentage of the saturation-paste of the soils in this study, CEC should be taken into account for dilution factor between ECe and EC1:5, and the suggested dilution factors might be reasonable estimate for the soil textural classes.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.776-781
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• 2010

Estimating the electrical conductivity of the saturation-paste (SP) is a common method to assess soil salinity. To assess soil salinity realistically, it is important to extract soil solution under field capacity. However, few studies on salinity assessment have been conducted for soil solution extracted under field capacity (-33 kPa; FC) moisture condition due to difficulty in soil solution extraction. This study was conducted to evaluate whether saturation-paste can represent field condition. Soil solutions were extracted from 22 soils in the plastic film house (PFH) and 18 soils in the reclaimed land (RL) at saturation and field capacity moisture conditions. Those were analyzed for pH, EC, cations ($K^+$, $Ca^{2+}$, $Mg^{2+}$, $Na^+$) and anions ($Cl^-$, ${NO_3}^-$, ${PO_4}^{3-}$, ${SO_4}^{2-}$). Both cations and anions of soil solution extracted from FC showed high correlations with ions extracted from SP in the PFH and the RL, except for ${NO_3}^-$, ${PO_4}^{3-}$ in the RL. Results of the t-test, the ECe and $EC_{FC}$ were not significant at significance level 0.05. The slopes of the equations between $EC_{FC}$ and ECe at more than sand 50% soils were higher than less than sand 50% soils, and differences of saturation percentage between SP and FC showed larger as increasing sand percentage. EC was related to soil water retention by soil texture. To determine the EC, soil texture and other soil properties which effect the soil moisture should be considered.

• Journal of Industrial Technology
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• v.3
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• pp.87-94
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• 1983

Heating characteristics of red pepper paste packed in report pouches of various thicknesses and their storage stability were investigated to determine the adequate processing conditions that good bacteriological safty and minimal quality changes could be obtained, when sterilized by using a steam-air system retort. A heat penetration into pouch-packed red pepper paste was carried out through by a conductive heat transfer, indicating a simple logarithmic heating curve, and the smaller thickness revealed the higher heat penetration rate, suggesting the possibility of high temperature-short time sterilization of red pepper paste. The processing conditions with Fo-value of 4.5 or higher were sufficient for keeping up bacterial safty, but based on C-value, better quality retention was obtained at pouch thickness of 15mm under the processing temperature of $120^{\circ}C$. Subsequent storage study revealed that the red pepper paste packed in 15mm and processed at $120^{\circ}C$ with Fo=4.5 could be held without any spoilage and overall acceptance change, when stored for 6 months at room temperature under the relative humidity of 70%. After 3 months storage in $38^{\circ}C$ under saturation humidity, overall acceptance of red pepper paste were judged not to be maintainable on the acceptable level, but it may be suggested that above the results could be kept up a desirable quality without any remarkable deterioration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.9
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• pp.835-843
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• 2008

We have fabricated the source-drain electrodes for OTFTs by screen printing method and manufactured Ag pastes as conductive paste. To obtain excellent conductivity and screen-printability of Ag pastes, the dispersion characteristics of Ag pastes prepared from two types of acryl resins with different molecular structures and Ag powder treated with caprylic acid, triethanol amine and dodecane thiol as surfactant respectively were investigated. The Ag pastes containing Ag powder treated with dodecane thiol having thiol as anchor group or AA4123 with carboxyl group(COOH) of hydrophilic group as binder resin exhibited excellent dispersity. But, Ag pastes(CA-41, TA-41, DT-41) prepared from AA4123 fabricated the insulating layer since the strong interaction between surface of Ag powder and carboxyl group(COOH) of AA4123 interfered with the formation of conduction path among Ag powders. The viscosity behavior of Ag pastes exhibited shear-thinning flow in the high shear rate range and the pastes with bad dispersion characteristic demonstrated higher shear-thinning index than those with good dispersity due to the weak flocculated network structure. The output curve of OTFT device with a channel length of 107 ${\mu}m$ using screen-printed S-D electrodes from DT-30 showed good saturation behavior and no significant contact resistance. And this device exhibited a saturation mobility of $4.0{\times}10^{-3}$ $cm^2/Vs$, on/off current ratio of about $10^5$ and a threshold voltage of about 0.7 V.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.6
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• pp.398-404
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• 2000

We examined the effect of soil:water ratio on the equivalent concentration of individual electrolyte species and the electrical conductivities (EC) of the diluted extracts of 24 soil samples (loam or silt loam) collected from rose-cultivated plastic houses to estimate the EC of saturated soil-paste extracts (ECe) from diluted soil extracts. With increasing volume ratio of water (higher dilution), the equivalent concentrations of each electrolyte species and their sum increased. The relative contribution to the EC, however, was highest for $NO_3{^-}$, irrespective of soil:water ratio. The measured ECe was 6.36 for loam and $8.09dS\;m^{-1}$ for silt loam soils and the corresponding soil:water ratio was 0.38 and 0.50, respectively. The EC_e estimated from the EC of diluted extracts at 1:1, 1:2, or 1:5 soil:water ratios using their corresponding uniform diluted factors was lower than the measured EC_e and this difference was greater with higher dilution and EC values. Therefore, the alternative diluted factors (y) for each soil: water ratio were obtained following the definition of diluted factor and were correlated significantly with volume ratios of added water (x): y=1.55x+0.5 for loam and y=1.21x+0.48 for silt loam soils. On the other hand, correlation analyses of the EC of soil extracts (y) to the volume ratio of added water (x) on log-log scale yielded linear models: logy = -0.805logx + logb, SD of slope=0.05, b=sample specific constant, n=24). With known saturation percentage of a sample representing a group and and the EC of diluted extract of a given soil, the EC_e could be predicted using the proposed logarithmic equation.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.4
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• pp.193-199
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• 2003

Electrical conductivity (EC) is a major indicator of soil salinity. Measurement of EC in saturation-paste extract of soil (ECe) is a standard way to evaluate soil salinity. However, many of the data on soil salinity have been obtained by measuring the EC of 1:5 soil-water extract (EC1:5) or salt percentage which is calculated from EC1:5 by multiplying a conversion factor. We analyzed 90 soil samples collected from 9 reclaimed tidelands in Korea, and derived relationships between ECe and dilution factors (DF1:5) which can convert EC1:5 to ECe in 2 soil textural groups at 5 salinity levels. Regression equations between ECe and DF1:5 were DF1:5 = 1.3624In(ECe) + 5.1386($r^2=0.37^{***}$) for soils of more than 50% silt content, DF1:5 = 1.9505In(ECe) + 5.3679($r^2=0.66^{***}$) for soils of less than 50% silt content. And the relationship for all soils investigated was DF1:5 = 1.4001In(ECe) + 5.4865($r^2=0.51^{***}$). From the relationships, conversion factors for calculation of ECe from EC1:5 of salt percentage data were estimated for soils of different textures and salinity levels.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.spc
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• pp.14-19
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• 2009

To obtain the basic data on reclaimed tideland soils, 90 soil samples were collected from 9 tideland reclamation project areas in Korea. The soils consisted of clay (2.0 to 35.0 percents), silt (2.0 to 80.0 percents), and sand (8.0 to 95.0 percents), and were dominantly classified sandy loam and silty loam. The soils had pH of 4.5 to 9.1, organic matter of 0.50 to $19.20g\;kg^{-1}$, total nitrogen of 4 to $1,159mg\;kg^{-1}$, and avaliable phosphorus (as $P2_O_5$) of 3.5 to $147.7mg\;kg^{-1}$. The electrical conductivity in soil saturation-paste extracts (ECe) ranged between $0.62dS\;m^{-1}$ and $31.60dS\;m^{-1}$ and the concentrations of sodium and magnesium ions were higher than those of potassium and calcium ions. The magnitude of the ECe was as low as that of normal level in Nam-Po, Pu-Sa, and Kye-Hwa reclamation project areas having sandy loam texture, but was as high as that of normal level saline-sodic level in Nam-Yang and So-Po reclamation project areas having silty loam texture even though the soils were cultivated more than 10 years as a paddy. Some part of Saemangeum area was surveyed and soil textures were various; some were silt loam and some were sandy loam. The ECe values were very high in topsoil and subsoil.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.195-195
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• 2017

The water in the crop cultivation shows difference according to the variety of crop, cultivations period and climatic condition. The growth and development, quantity and fruit enlargements are affected by soil water conditions. In previous study, leaf area and photosynthesis are decreased by lower soil moisture. Other research reported that excess moisture condition at vegetative and reproductive growth period in cultivation of soybean caused highest reduction in crop growth rate (CGR) and dry weights of plant parts. In particular, the damage was bigger during vegetative growth stage than reproductive growth period. Soybean (Glycine max (L.) Merill) is useful and popular crop throughout the world. It is very popular crop in Korea, China, Japan and other Asian countries. Soybeans used in various way including soybean sprouts, paste, soymilk, oil and tofu. Two soybean cultivars grown in four different irrigation conditions were determined for physiological responses. In this study, we examined leaf area (LA), leaf dry weight (LDW), specific leaf area (SLA), root dry weight (RDW) and shoot height (SH) in different water conditions. 50mL/9day irrigation periods showed the lowest contents in LA, LDW, RDW, SH. Water deficit caused increase of leaf Water saturation deficits (WSD), Cheongjakong 3 and Taekwangkong showed increase of leaf water saturation deficits (WSD) in drought conditions and leaf water potential and stomatal conductance were decreased. Photochemical efficiency was decreased in 50mL/1day irrigation condition while, there was decrease of growth and development in 50mL/9day with drought.

• Journal of the Korean Geophysical Society
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• v.2 no.3
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• pp.225-233
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• 1999

Electrical resistivity of a rock-sample is dependant on not only formation factor of rock itself but also many parameters such as fluid type, measuring device, temperature, water saturation, electrical contact between electrode and core section, induced polarization, and frequency of electric source. In this study, we attempt to verify various affecting factors in core resistivity measurements and to find a better environment for core resistivity measurement. Particularly great attention has been paid to understanding the effects of temperature, water saturation, contact condition between sample and electrodes, and frequency of electric source. Precise measurement of resistivity can be achieved by utilizing silver paste for better contacts, taping samples for constant moisture contents, and using time-series resistivity data.

• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.219-224
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• 2003

Fly ashes containing 6.1~16.5 wt% of unburned carbon were treated thermally at 500$^{\circ}C$ for 3 h and thus, the content of unburned carbon was decreased below 2.1 wt%, the range of particle size distribution became narrower and the mean particle size became smaller. Besides, the properties of particles in fly ashes were improved, particularly the particle shape became close to a spherical type. The fluidity of cement pastes containing fly ashes treated previously at 500$^{\circ}C$ for 3 h was increased much than that of cement pastes containing original fly ashes. When the added amount of superplasticizer was over the saturation amount, there was no correlation between the amount of unburned carbon in fly ashes and the apparent viscosity of cement pastes actually. On the contrary, when the added amount of superplasticizer was below the saturation amount, there was a correlation.