• Korean Journal of Soil Science and Fertilizer
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• v.10 no.3
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• pp.153-170
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• 1977

Considering the ways for the possible improvement of soil test for upland crops, various methods for the evaluation of K supplying power and testing of available soil K were reviewed in terms of theoretical principles and practical usefulness of the each method. The review was also made on the characteristics of upland crops in K requirement and on the chemical properties of major korean upland and lowland rice soils in terms of K availability. Following is the few remarks drawn from the review. 1. Quite large number of methods have been known for the evaluation of K supplying power and testing for available soil K. In nature, they can be divided into two categories; capacity-based methods and intensity-based methcds. The capacity-based methods usually measure the exchangeable and some portion of nonexchangeable K, while the intensity-based methods suggest to consider the ractivity ratios of major cations in soil solution and the energy requirement for the replacement of exchangeable soil K into soil solution. 2. As methodology for extraction of interested part of soil K, chemical extraction, electrodialysis and ion exchange methods have been known. Among these, chemical extract ion is favorable because of its simplicity. However, recently suggested Electro-Ultra-Filtration method seems to merit further study for wider use for not only K but also other nutrient availability of soils. 3. The intensity-based methods, although they are more theoretical, because of their complexity, in methods may not be adapted for practical soil tests. 4. The exchangeable K which is rather simple to measure and which well reflects the status of K reserve as nonexchangeable and is immediate pool of water soluble K may be good, if not best, criterion of soil K availability to plant in common soil testing. 5. Because there are evidences that the abundance of available K alone may not be good inclication for availability of K to plant, it is recommendable to interprete the exchangeable K data as percent saturation of exchangeable K to total C. E. C. of soil for the recommend ation of K fertilizer based on soil tests. 6. Some pot and field trial results showed the trends that percent potassium saturation to total C. E. C. better serve as the parameter for K fertilizer recommendation.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.3
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• pp.179-188
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• 1994

This study was conducted to investigate the distribution of potassium fractions and to establish the soil chemical indices for assessing potassium availability in upland soil. Soil samples were collected from 66 vegetable crop fields of Chungbuk Jungweon, Jeonbuk Imsil and Kyengbuk Euiseong and these samples were analyzed water soluble(W. S. -K), exchangeable(Exch. -K) and nonexchangeable potassium(Nonex. -K). The distribution of potassium fractions was examined for soils having different physico-chemical properties and compared with the soil parameters related to the potassium availability. 1. The distribution ranges of W.S.-K, Exch.-K and Nonex.-K were 0.07~1.42, 0.27~2.30, and 0.84~4.74me/100g, and average contents of relevent fractions were 0.40, 1.03 and 2.37me/100g respectively. 2. Contents of W.S.-K and Exch.-K were decreased with increasing soil pH, CEC, Exch. Ca and Exch. Mg contents but Nonex. -K showed a low correlationship with these factors. 3. Exch.-K content slightly inereased with increasing clay content, while W.S.-K and Nonex. -K contents were grandually decreased with clay contents. 4. The relationship between W.S.-K and Exch.-K was significant and W.S.-K was released from soil at 0.23me/100g content of Exch.-K 5. Contents of W.S-K and Exch.-K showed high correlationship with soil chemical parameters such as ratio of exchangeable cations(K/Ca+Mg), ratio of exchangeable cation equivalent[$K/{\sqrt{Ca+Mg}}:(me/100g)^{1/2}$], potassium exchangeable free energy(${\Delta}F=RT$ 1n $K/{\sqrt{Ca+Mg}}$ : calories/mole) and saturation percentage of potassium($Exch.K/CEC{\times}100$), and these factors were considered to be good parameters for assessing soil potassium availability.

• The Journal of Engineering Geology
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• v.13 no.3
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• pp.293-308
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• 2003

New results about the crustal structure down to a depth of 60 km beneath North Korea were obtained using the seismic tomography method. About 1013 P- and S-wave travel times from local earthquakes recorded by the Korean stations and the vicinity were used in the research. All earthquakes were relocated on the basis of an algorithm proposed in this study. Parameterization of the velocity structure is realized with a set of nodes distributed in the study volume according to the ray density. 120 nodes located at four depth levels were used to obtain the resulting P- and S-wave velocity structures. As a result, it is found that P- and S-wave velocity anomalies of the Rangnim Massif at depth of 8 km are high and low, respectively, whereas those of the Pyongnam Basin are low up to 24 km. It indicates that the Rangnim Massif contains Archean-early Lower Proterozoic Massif foldings with many faults and fractures which may be saturated with underground water and/or hot springs. On the other hand, the Pyongyang-Sariwon in the Pyongnam Basin is an intraplatform depression which was filled with sediments for the motion of the Upper Proterozoic, Silurian and Upper Paleozoic, and Lower Mesozoic origin. In particular, the high P- and S-wave velocity anomalies are observed at depth of 8, 16, and 24 km beneath Mt. Backdu, indicating that they may be the shallow conduits of the solidified magma bodies, while the low P-and S-wave velocity anomalies at depth of 38 km must be related with the magma chamber of low velocity bodies with partial melting. We also found the Moho discontinuities beneath the Origin Basin including Sari won to be about 55 km deep, whereas those of Mt. Backdu is found to be about 38 km. The high ratio of P-wave velocity/S-wave velocity at Moho suggests that there must be a partial melting body near the boundary of the crust and mantle. Consequently we may well consider Mt. Backdu as a dormant volcano which is holding the intermediate magma chamber near the Moho discontinuity. This study also brought interesting and important findings that there exist some materials with very high P- and S-wave velocity annomoalies at depth of about 40 km near Mt. Myohyang area at the edge of the Rangnim Massif shield.

• The Journal of Engineering Geology
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• v.25 no.1
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• pp.93-102
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• 2015

The characteristics of frozen soils are one of most important factors for foundation design in cold region. The objective of this study is to evaluate the shear strength and stiffness of frozen soils according to the confining conditions during the freezing and shearing phase. A direct shear box is constructed for the frozen specimens and bender elements are mounted on the wall of the shear box to measure shear wave velocities. Specimens are prepared by mixing sand and silt with a silt fraction of 30% in weight and the degree of saturation of 10%, giving a relative density of 60% for all tests. The temperature of the specimens in the freezer is allowed to fall below -5℃, and then direct shear tests are performed. A series of vertical stresses are applied during the freezing and shearing phase. Shear stress, vertical displacement, and shear wave along the horizontal displacement are measured. Experimental results show that in all the tests, shear strength increases with increasing vertical stress applied during the freezing and shearing phases. The magnitude of the increase in shear strength with increasing vertical stress during shearing under fixed vertical stress in the frozen state is smaller than the magnitude of the increase in vertical stress during freezing and shearing. In addition, the change in shear wave velocities varies with the position of the bender elements. In the case of shear waves passing through the shear plane, the shear wave velocities decrease with increasing horizontal displacement. This study provides an evaluation of the properties of shear strength and stiffness of frozen soils under varied confining condition.

• The Korean Journal of Pesticide Science
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• v.6 no.1
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• pp.16-24
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• 2002

Research trends in the measurement of foliar uptake of pesticides and the recently proposed action mechanism of the surfactant-induced uptake of pesticides were reviewed with the related reports and studies. Major techniques used in those fields are bioassay, radiotracer techniques with leaves or cuticular membrane. Recently, a new method using Congo Red as a tracer was proposed. The limiting factor in the pesticides uptake into leaves is the waxy layer which consists of the epicuticular and cuticular wax. Physico-chemical parameters such as molar volume, water solubility and partition coefficient of pesticides have limited influences on the pesticide uptake into leaves. Polydisperse ethoxylated fatty alcohol surfactants are well known as the good activator for many pesticides. It is now generally agreed that uptake activation is not related to the intrinsic surface active properties of surfactants such as surface activity, solvent property, humectancy and critical micelle concentration. Recent studies using ESR-spectroscopy revealed that the surfactants have an unspecific plasticising effect on the molecular structure of the wax and cuticular matrix, leading to increased mobilities of pesticides. Penetration of surfactants into waxy layer altered the pesticide mobility in wax and the partition coefficient of pesticide, and then the pesticides penetration into leaves was enhanced temporally. The enhancing effect of surfactant could be significantly different depending on the carbon number of aliphatic moiety and the number of ethoxy group in polyoxyethylene chain of surfactants. It is suggested that the rate of penetration of surfactants should have a significant relationship with the rate of penetration of pesticides.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.1
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• pp.53-60
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• 2010

Purpose: We try to calculate EDW-factor easily with the formula applies essential data of EDW-factor and evaluate the validity through a measurement. Materials and Methods: We used the given value of GSTT (Golden Segmented Treatment Table) for the calculation of the EDW-factor. As to the experimental device, 0.6 cc farmer-type ion-chamber, an electrometer and water- phantom were used. A measurement was made at the maximum dose depth of the photon beam energy 6 MV and 15 MV under the condition that SSD (Source to Surface Distance) was 100 cm. The angle of the EDW (Enhanced Dynamic Wedge) which we use in an experiment was 60 degree, 30 degree, 20 degree in the Y1-OUT direction. We used Eclipse planning system (Varian, USA) as RTP system and the EDW-factor was calculated about all fields and EDW direction. In order to show the EDW-factor feature, a measurement was made at the selected field that verify the influence of the dependability about X, Y jaw and off-axis field. Results: When we change the Y1 field, it influence on the EDW-Factor and measured value. But the error between measured values and calculated values was less than 1%. The experimental result indicated the tendency that the error of the result of calculation and measured value becomes smaller as the EDW angle become smaller whether the calculation point (measurement point) and iso-center are same or not. The influence of the field size and energy did not show up. We simulated with the same condition using the RTP system. And we found that it makes no difference between the MU which is calculated manually by applying the EDW-Factor obtained from the commercial program and the value which is calculated by using RTP system. Conclusion: We excluded fitting value from well-known EDW-Factor formula and calculated EDW-factor with the formula applies essential data of EDW-factor only. As a result, there are no significant difference between the measured value and calculated value and it showed errors less than 1%. Also, we implemented the commercial program to calculate EDW-Factor conveniently without measure a factor on each field.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.44-49
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• 2004

Changes in quality properties of Kochujang prepared with Paecilomyces japonica powder and extract using different solvents were investigated during 90 days of fermentation at $20^{\circ}C$. Although moisture contents were not significantly different, pH of P. japonica-added Kochujang was lower than that of control group without P. japonica, and decreased with increasing fermentation time. Amino nitrogen content increased up to 60 days of fermentation and decreased slightly after 90 days, with that of P. japonica-added Kochujang showing highest on 30 and 60 days at 179.2 and 282.2 mg%, respectively, higher than control gruup. L, a, and b values decreased in proportion to fermentation period, with P. japonica-added Kochujang, particularly P. japonica powder-added Kochujang, lower than those of control g개up. Sensory evaluation test showed color of control group was 'clear red', whereas that of P. japonica powder-added Kochujang was 'dark reddish brown' and P. japonica extract-added Kochujang was darker than control group; consumer preference for dark color was low, Textures of all samples were 'glossy and smooth', showing high consumer preference. Salt content of P. japonica-added Kochujang was higher than that of control group, with P. japonica extract-added Kochujang higher than that made with powder Hot taste or P. japonica-added Kochujang was weaker, whereas its flavor higher, than control group, with P. japonica powder-added Kochujang showing highest flavor score. Overall preference was higher for P. japonica-added Kochujang than control group, with P. japonica water extract-added Kochujang showing the highest score.

• Korean Journal of Food Science and Technology
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• v.10 no.2
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• pp.263-268
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• 1978

To find out the possible variation in chemical composition among ginseng products, the amount of saponin, extract and other basic components in different age and portion of ginseng roots(Panax ginseng Meyer) were investigated and compared with. (1) Great difference in the amount of ash, crude protein, fiber, fat, total sugar and reducing sugar was observed among different portion of the root comparing with those of different age of the root. That of ash, crude fiber, saponin and extract produced was higher in epidermis, fiber roots and subterranean stems, while that of crude protein, total sugar, panaxadiol/panaxatriol was higher in central portion and branch of the root. (2) The amount of extract produced was affected by the solvent used. Higher amount was obtained when water was employed. It was decreased as the increase of the concentration of alcohol solvent. Futhermore, the composition and physical properties were greatly varied by the concentration of alcohol solvent. (3) The amount of total-N, $P_2O_5,\;K_2O$, and ash was higher in two to three years old roots, while those of crude $SiO_2,\;CaO,$ crude fiber, and total sugar was higher in order roots. No difference was found in amount of MgO, Fe, Zn, and Na among age of the root.

• Microbiology and Biotechnology Letters
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• v.7 no.2
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• pp.75-89
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• 1979

One strain of Penicillium sp. (175-66-B), isolated from soil, was able to produce a substance that has a strong inibition activity against the Agkistrodon and Trimeresurus venoms. In this experiment, the chemical and biological properties of the sample were investigated. As an inhibitory substance, it was effective to the proteinase, hemorrhagic and lethal factors of Agkistrodon and Trimeresurus venoms, and also effective to several fractions of the proteinases and hemorrhagic factors of Agkistrodon halys blomhoffi venom. Moreover, in the addition of prednisotone, it was more effective for the cure of the mouse envenomated with the venom amount of two fold of MLD$_{100}$. This substance was very stable to the acid, alkali and heat. Its melting point was high enough to sublime at 222$^{\circ}C$ without any decomposition. This sample was easily dissolved only in hot water, but not in several organic solvents except for a little dissolution in elate. It did not have the chelating activity. It had very strong specificity to the snake venoms. but its activity was depressed by the addition of zinc or cupric salts. This sample had no acute toxicity to the mouse. Its chemical formula was $C_{16}$ $H_{12}$$N_2$ $O_{10}$ with the molecular weight of about 392. It has two epoxy groups and four carboxyl radicals, but amino, nitrite and nitrate radicals, unsaturated bonds and aromatic ring were not detected. Theuchemical configuration of this sample was suggested to be;

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.235-242
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• 2015

The objective of this study was to determine the effects of soluble potassium silicate by soil drenching application on watermelon growth, yield, and nutrient uptake. The potassium silicate rates were control (No potassium silicate), 1.63mM, 3.25mM, 6.50mM. The potassium silicate were treated 6 times (twice before fruit forming and 4 times after fruit forming per 7 day. Soil chemical properties, such as soil pH, EC, available phosphorus and silicate, exchangeable K, nitrate-N levels were increased after potassium silicate treatment, while the concentrations of soil organic matter, exchangeable Ca and Mg were similar to control. The growth characteristics of watermelon, such as stem diameter, fresh and dry weight of watermelon at harvest were thicker and heavier for increased potassium silicate treatment than the control, while number of node, and plant length were same for all treatments. With increased potassium silicate treatment, nutrient concentrations, such as P and K in the watermelon leaf at harvest were increased, N concentration in the leaf was decreased, and Ca and Mg concentrations in the leaf were same. Chlorophyll content was increased with increased potassium silicate application. The occurrence of powdery mildew was lower for the potassium silicate treatments than the control. Fresh watermelon weight for the potassium silicate treatments was 0.1 to 0.5kg per watermelon heavier than the control, sugar content was 0.5 to $0.6^{\circ}Brix$ higher than control, and merchantable watermelon was 2 to 4% increased compared to the control. These results suggest that potassium silicate application by soil drenching method in the greenhouse can improve watermelon nutrient uptake, merchantable watermelon and suppress the occurrence of powdery mildew.