• Korean Journal of Environmental Agriculture
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• v.22 no.1
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• pp.65-69
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• 2003

The adsorption characteristics of [$^{14}C$] mefenacet were investigated with six types of soil collected from different locations. The equilibrium time for adsorption was five hours. The adsorption coefficient(Kf) of Namwon series (volcanic ash soil) showed the highest value of 89.2 while Daejeon series (loamy sand) showed the lowest value of 2.37. The Kf values decreased in order of silty clay loam > silty loam > loamy sand > sandy loam, and the effect of soil properties on the adsorption of mefenacet in soil increased in order of clay mineral < CEC < organic matter. No significant effect was observed by the change of soil pH. The ground water ubiquity scores (GUS index) were $1.20{\sim}1.77$ in three types of soil while $1.81{\sim}2.42$ in the others, indicating that the former group belonged to nonleachers and the latter group to the transitional. Mefenacet in the test soil series seemed to have low possibility of contaminating ground water.

• Journal of the Korean Chemical Society
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• v.17 no.1
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• pp.20-24
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• 1973

The average fission neutron cross sections were determined for the following reactions, $^{93}Nb(n,\alpha)^{90}Y$, $^{90}Zr(n,p)^{90}Y$,$^{93}Nb(n,\alpha)^{90m}Y$and$^{90}Zr(n,p)^{90m}Y$. The cation exchange column was used for the quantitative separation of the product nuclides using $\alpha-$hydroxyisobutyric acid as the eluent. The absolute activites of $^{90m}Y$ and $^{90}Y$were determined by the gamma ray spectrometry and a calibrated $2\pi$gas flow counter, respectively. The cross sections of $^{93}Nb(n,\alpha)^{90}Y$, $^{90}Zr(n,p)^{90}Y$,$^{93}Nb(n,\alpha)^{90m}Y$and $^{90}Zr(n,p)^{90m}Y$ reactions were found to be$0.14\pm0.01mb$, $0.83\pm0.02mb$, $0.018\pm0.02mb$ and $0.33\pm0.02mb$, respectively. The possible use of $^{90m}Y$ instead of $^{90}Y$ was discussed as a better means for the determination of niobium.

• Journal of the Korean Electrochemical Society
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• v.17 no.1
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• pp.7-12
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• 2014

There is increasing demand on the reducing the weight and the volume of the major components in lithium secondary battery to improve energy density. Separator not only provides pathway for lithium ion movement but also prevents direct contact between anode and cathode. Herein we fabricated polyethylene separator by varying biaxial stretching ratio to obtain membrane thickness of 16, 12, and $9{\mu}m$. Mechanical and thermal properties of the separator with different thickness were investigated. Also rate capability and charge-discharge cycle property up to 500 cycles were studied using coin type full-cell with $LiCoO_2$ and graphite as a cathode and an anode, respectively. All the cells using separator with different thickness demonstrated excellent capacity retention after 500cycles (around 80%). Considering the rate capability, cell using separator with thickness of $9{\mu}m$ showed best performance. Interestingly, separator thickness of $9{\mu}m$ was more resistant to heat contraction compared to that of $16{\mu}m$ separator.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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• pp.625-637
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• 1997

Calcium ions are implicated in a variety of physiological functions, including enzyme activity, membrane excitability, neurotransmitter release, and synaptic transmission, etc. Calcium antagonists have been known to be effective for the treatment of exertional angina and essential hypertension. Selective and nonselective voltage-dependent calcium channel blockers also have inhibitory action on the acute and tonic pain behaviors resulting from thermal stimulation, subcutaneous formalin injection and nerve injury. This study was undertaken to investigate the effects of iontophoretically applied $Ca^{++}$ and its antagonists on the responses of WDR (wide dynamic range) cells to sensory inputs. The responses of WDR cells to graded electrical stimulation of the afferent nerve and also to thermal stimulation of the receptive field were recorded before and after iontophoretical application of $Ca^{++}$, EGTA, $Mn^{++}$, verapamil, ${\omega}-conotoxin$ GVIA, ${\omega}-conotoxin$ MVIIC and ${\omega}-agatoxin$ IVA. Also studied were the effects of a few calcium antagonists on the C-fiber responses of WDR cells sensitized by subcutaneous injection of mustard oil (10%). Calcium ions and calcium channel antagonists ($Mn^{++}$, verapamil, ${\omega}-conotoxin$ GVIA & ${\omega}-agatoxin$ IVA) current-dependently suppressed the C-fiber responses of WDR cells without any significant effects on the A-fiber responses. But ${\omega}-conotoxin$ MVIIC did not have any inhibitory actions on the responses of WDR cell to A-fiber, C-fiber and thermal stimulation. Iontophoretically applied EGTA augmented the WDR cell responses to C-fiber and thermal stimulations while spinal application of EGTA for about $20{\sim}30\;min$ strongly inhibited the C-fiber responses. The augmenting and the inhibitory actions of EGTA were blocked by calcium ions. The WDR cell responses to thermal stimulation of the receptive field were reduced by iontophoretical application of $Ca^{++}$, verapamil, ${\omega}-agatoxin$ IVA, and ${\omega}-conotoxin$ GVIA but not by ${\omega}-conotoxin$ MVIIC. The responses of WDR cells to C-fiber stimulation were augmented after subcutaneous injection of mustard oil (10%, 0.15 ml) into the receptive field and these sensitized C-fiber responses were strongly suppressed by iontophoretically applied $Ca^{++}$, verapamil, ${\omega}-conotoxin$ GVIA and ${\omega}-agatoxin$ IVA. These experimental findings suggest that in the rat spinal cord, L-, N-, and P-type, but not Q-type, voltage-sensitive calcium channels are implicated in the calcium antagonist-induced inhibition of the normal and the sensitized responses of WDR cells to C-fiber and thermal stimulation, and that the suppressive effect of calcium and augmenting action of EGTA on WDR cell responses are due to changes in excitability of the cell.

• Development and Reproduction
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• v.2 no.2
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• pp.205-212
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• 1998

A sodium-independent facilitative glucose transporter 1 (Glut1) is a major route by which glucose can be transported across the plasma membrane of mouse embryo. Although it has been known that insulin-like growth factor-I (IGF-I) promotes glucose transport into the mouse embryo, whether IGF-I directly regulates transcription of Glut1 has been uncovered in mouse preimplantation embryo. This study was aimed to elucidate the role of glucose and IGF-I in development and Glut1 expression in preimplantation mouse embryo. Two-cell embryos developed in blastocyst regardless of the glucose in the presence of pyruvate. IGF-I significantly increased the number of blastomeres in the mid-blastula. Deprivation of glucose did not affect the amount of Glut1 transcripts in morula cultured from 2-cell embryo. IGF-I potentiated Glut1 expression in morula cultured from 2-cell embryo even in the absence of glucose. Taken together, it is concluded that depletion of glucose does not promote Glut1 expression the in morula cultured form 2-cell embryo, and that increment of Glut1 expression possibly mediates embryotropic effect of IGF-I on preimplantation mouse embryo.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.3
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• pp.279-284
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• 2015

As non-conventional oil resources such as shale gas have been widely developed, proper treatment of flowback and produced water is becoming important. However, application of conventional water treatment techniques is limited due to high concentration of pollutants such as oil and grease, organics, harmful chemicals, and inorganic ions. In this study, we examined the feasibility of using forward osmosis (FO) and air gap membrane distillation (AGMD) as novel treatment options for shale gas wastewater. Laboratory-scale FO and MD devices were fabricated and used for the experiments. Results showed that FO could be used to treat the synthetic wastewater. Using 5 M NaCl as the draw solution, the flux was approximately $6L/m^2-hr$ during the treatment of low range wastewater (TDS: 66,000 mg/L). Nevertheless, AGMD was more effective to treat high range wastewater (Total Dissolved Solid: 260,000 mg/L) than FO.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.1
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• pp.10-16
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• 1991

Mean values and the relative contribution of OM and clay to total CEC for soil textural classes were obtained from the analytical results of the typical profiles(sample size : 3,182) which were described by the detailed soil maps througthout Korea with an exception of Jeju island. The results are below. 1. Mean values of the soil CEC were 2.9 for S, 4.7 for LS, 6.7 for SL, 9.0 for L, 10.2 for SiL, 10.7 for CL, 8.6 for SCL, 12.2 for SiCL, 16.1 for SiC, and 17.4me/100gr for C, respectively. 2. The multiple regression equation and partial regression coefficient tended to show that OM and clay had the highly significant effect on CEC. 3. Clay content of the coarse, moderately coarse, and moderately fine soil was 1.10 to 1.89 times as important as OM content whereas OM of the medium and fine soil 1.09 to 2.94 times as important as clay in predicting CEC. 4. Mean values of CEC of the humus and clay in Korean soils were about 62.9 and 24.0me/100gr, respectively.

• Journal of Korean Society of Forest Science
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• v.87 no.2
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• pp.270-275
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• 1998

The management of pine-mushroom forest means the environmental control for fairy ring of Tricholoma matsutake. Thus, the management demands intensive study for keeping healthy condition of the fairy ring, and that for the measurement of active portion of the soil ecosystem. This study was conducted to investigate the impact of T. matsutake fungus on the soil physicochemical properties and dehydrogenase activity by dividing the fairy ring into 3 regions such as 'zone of decayed mycorrhizae', 'zone of physiologically active mycorrhizae', and 'in front of fairy ring'. The passing of T. matsutake did not result in significant changes in canon contents of soils, but available phosphorus, carbon, and nitrogen contents were different between the soils of active mycorrhizal zone and that in front of fairy ring. The dehydrogenase activity around the fairy ring of T. matsutake was quite lower than that in general forest soils, which indicated that the fairy ring of T. matsutake was built up in the relatively immature soils which contain little organic matter. Thus, the dehydrogenase activity of soil was thought to be used as an index for the management of pine-mushroom forest with considering that the management practically means the environmental control for keeping good conditions for the development of fairy ring of T. matsutake. Especially, the dehydrogenase activity measurement can be recommended as a tool for time-decision of litter removal by floor raking since the activity is a good index of litter decomposition.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.53-60
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• 2017

Fly ash(FA) which is a byproduct in the coal combustion in thermal power plant contributes to pore structure densification due to pozzolanic reaction, and this leads to long-term strength development and excellent resistance to chloride penetration. In the work, compressive strength and chloride resistance in OPC(Ordinary Portland Cement) and FA-based concrete are evaluated, and the relationships are investigated considering ages. For the work, 3 different W/B (Water to Binder) ratios of 37%, 42%, and 47% are prepared, and 3 substitution ratio of fly ash(0%, 30%, and 50%) are considered as well. At the age of 28 days and 180 days, test results of compressive strength, diffusion coefficients based on Tang's method, and passed charges referred to ASTM C 1202 and KS F 2711 are obtained. With increasing replacement ratio of FA and decreasing W/B, the resistances to chlorides(diffusion coefficient and passed charge) are improved, and the results at the age of 180 days decrease to only 15% level at the age of 28 days due to pozzolanic reaction in FA 50 mixture, which shows that resistance to chloride is much dependent on age effect than strength development. After 180 days, more clear linear relationships are observed between strength and resistance to chloride.

• Journal of the Korean Chemical Society
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• v.46 no.4
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• pp.363-377
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• 2002

The purpose of this study was to improve the problems of the voltaic cell described in the science textbooks of secondary schools. For this purpose, the contents of science textbooks which are related to the voltaic cell were analyzed and the problems which were not explained clearly by theorems were tried to be explained by experiments, and lastly sug-gestions were made toward the improvements regarding the voltaic cell in the science textbooks. The findings are that there are problems on the ways of ensuring whether the voltaic cell operates properly as a chemical battery, on the explanation of why the hydrogen bubbles form at the zinc electrode, on the cell potential, on the unification of the electrode terminology used, and on the mention of the current. Solutions to the problems except the cell potential were suggested. According to the experiment, the theoretical potential was calculated by considering the potentials of redox reactions at the two electrodes of the cell and by taking into account the characteristics of the electrodes such as the work function, ionization energy, stan-dard reduction potential, and electronegativity.The cell potential of the voltaic cell is explained by several factors. In the improved version of the textbook's introduction section to the voltaic cell, it is necessary to describe the voltaic cell his-torically.For the conceptual section, it should be explained in terms of the Daniel cell.