• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.967-976
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• 2023

Biochar is emerging as a promising substance for achieving carbon neutrality and climate change mitigation. It can absorb several nutrients via ion bonding on its surface functional groups, resulting in slow dissociation of the bonds. Biochar, like organic fertilizers, contributes to sustainable nutrient management. The purpose of this study was to investigate the effects of nutrient-coated biochar amendments on leafy vegetables production and soil fertility. The nutrient-coated biochar was produced by soaking rice husk biochar in a nutrient solution containing nitrogen (N), phosphorus, and potassium for 24 hours. Nutrient-coated biochar and organic fertilizers were applied to soil at a rate of 120 kg·N·ha^-1. The growth components of the leafy vegetables showed that nutrient-coated biochar led to the highest fresh weight (FW) of both lettuce and kale (i.e., 146.67 and 93.54 g·plant^-1 FW, respectively). As a result, nutrient-coated biochar amendments led to superior yield compared to the control treatment and organic fertilization. The elemental composition of leafy vegetables revealed that soil amended with nutrient-coated biochar resulted in higher nutrient contents, which was attributed to the high nutrient contents supplied by the rice husk biochar. Soil amendment with nutrient-coated biochar positively enhanced the soil fertility compared to amendment with organic fertilizer. Therefore, nutrient-coated biochar is a promising substance for enhancing agronomic performance of leafy vegetables and improving soil fertility.

• Journal of Radiation Industry
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• v.17 no.4
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• pp.543-549
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• 2023

Thallium-201 (²⁰¹Tl) is a medical radioisotope which emits gamma rays when it decays and used in myocardial perfusion scans in single-photon emission tomography due to its similar properties to potassium. Currently, the Korea Institute of Radiological & Medical Sciences is the only institution producing ²⁰¹Tl in Korea, and optimization of ²⁰¹Tl production research is necessary to meet supply compared to domestic demand. To this end, technical analysis of plating target production and chemical separation methods essential for ²⁰¹Tl production research is conducted. It deals with the process of generating and separating ²⁰¹Tl radioisotope and target production, It can be generated through a nuclear reaction such as ^natHg(p,xn)²⁰¹Tl, ²⁰¹Hg(p,n)²⁰¹Tl, ^natPb(p,xn)²⁰¹Bi → ²⁰¹Pb → ²⁰¹Tl, ²⁰⁵Tl(p,5n)²⁰¹Pb → ²⁰¹Tl, and considering impure nuclide generated simultaneously with the use of proton beam energy of 35 MeV or less, it is intended to be produced using the ²⁰³Tl(p,3n)²⁰¹Pb→²⁰¹Tl nuclear reaction. In particular, the chemical separation of Tl is a very important element, and the chemical separation methods that can separate it is broadly divided into four types, including solid phase extraction, liquid-liquid, electrochemical, and ion exchange membrane separation. Some chemical separations require additional separation steps, such as methods using selective adsorption. Therefore, this technical report describes four chemical separation methods and seeks to separate high-purity ²⁰¹Tl using a method without additional separation steps

• 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.

• Journal of the Mineralogical Society of Korea
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• v.28 no.3
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• pp.245-253
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• 2015

The performance of $TiO_2$ photo-catalytic oxidation process is significantly dependent on the amount of hydroxyl radicals produced during the process, and it is an essential prerequisite to quantify its production. However, precise and accurate methods for quantification of hydroxyl radicals have not been developed so far. For this reason, this study was initiated to compare existing methods for analysis of hydroxyl radicals produced by $TiO_2$ photo-catalytic oxidation and to propose a new method to overcome the limitation of established methods. To simulate $TiO_2$ photo-catalytic oxidation process, Degussa P25 which has been widely used as a standard $TiO_2$ photo-catalyst was used with the dose of 0.05 g/L. The light source of process was UVC mercury low-pressure lamp (11 W, $2,975mW/cm^2$). The results indicate that both potassium iodide (KI)/UV-vis spectrometer and terephthalic acid (TPA)/fluorescence spectrometer methods could be applied to qualitatively measure hydroxyl radicals via detection of triiodide ion ($I_3{^-}$) and 2-hydroxyterephthalic acid which are produced by reactions of iodine ion ($I^-$) and TPA with hydroxyl radicals, respectively. However, it was possible to quantitatively measure hydroxyl radicals using TPA method coupled with high-performance liquid chromatograph (HPLC). The analytical results using TPA/HPLC method show that hydroxyl radical of 0.013 M was produced after 8 hours operation of photo-catalytic oxidation under specific experimental conditions of this study. The proposed method is expected to contribute to precise the evaluation of the performance of photo-catalytic oxidation process.

• Analytical Science and Technology
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• v.23 no.6
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• pp.531-536
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• 2010

A quantitative analytical method has been established for the measurement of inosine 5'-monophosphate dehydrogenase (IMPDH) activity in human peripheral blood mononuclear cells (PBMCs) by ion-pair reversed-phase high performance liquid chromatography equipped with ultraviolet detection (HPLC/UV). IMPDH is a ${\beta}$-nicotinamide adenine dinucleotide hydrate (NAD+)-dependent dehydrogenase in which the enzyme converts inosine 5'-monophosphate (IMP) into xanthosine 5'-monophosphate (XMP). Its activity was measured by quantifying a HPLC chromatogram corresponding to XMP produced during the incubation of lysed PBMCs with IMP as a substrate and $NAD^+$ as a coenzyme. XMP produced was detected at a wavelength of 260 nm. The mobile phase was composed of a mixture of 37 mM potassium dihydrogen phosphate containing 7 mM tetra-n-butylammonium hydrogen sulfate adjusted to pH 5.5 and methanol (85:15, v/v) with a flow rate of 1 mL/min. The calibration curve was linear ($r^2$=0.999999) in the range of $0.2-50.0\;{\mu}M$ and the limit of quantification (LOQ) was $0.2\;{\mu}M$. The intra- and inter-day precisions were between 0.88-1.47% and 0.85-5.24%, respectively. The intra- and inter-day accuracies were between 98.74-99.99% and 99.95-101.65%, respectively. IMPDH activity in 11 Korean healthy volunteers ranged from 18.29 to 36.60 nmol/h/mg protein (mean = $27.70{\pm}6.28\;nmol/h/mg$ protein).

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.513-521
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• 2009

The primary goal of this research was to develop an optimized analytical procedure for soil analysis based on ion-selective microelectrodes for agricultural purposes, which can perform on-site measurement of various ions in soil easily and rapidly. For the simple and rapid on-site diagnosis, an analysis of soil chemicals was performed employing a multicomponent-in-situ-extractant and an evaluation of ionselective microelectrodes were conducted through the regressive correlation method with a standard analytical approach widely employed in this area. Examination of sensor responses between various soil nutrient extractants revealed that 0.01M HCl and 1M LiCl provided the most ideal Nernstian response. However, 1M LiCl deteriorated the selective response for analytes due to high concentration (1M) of lithium cation. Thus, employing either 0.1M HCl as an extractant followed by 10 times dilution, or 0.01M HCl as an extractant without further dilution was chosen as the optimal extractant composition. A study of regressive correlation between results from ion-selective microelectrodes and those from the standard analytical procedure showed that analyses of $K^+$, $Na^+$, $Ca^{2+}$, and $NO_3{^-}$ showed the excellent consistency between two methods. However, the response for $NH_4{^+}$ suffered the severe interference from $K^+$. In addition, the selectivity for $Mg^{2+}$ over $Ca^{2+}$ was not sufficient enough since available ionophores developed so far do not provide such a high selectivity for $Mg^{2+}$. Therefore, as an agricultural on-site diagnostic instrument, the device in development requires further research on $NH_4{^+}$ analysis in the soil sample, development of $Mg^{2+}$-selective ionophore, and more detailed study focused on potassium, one of the most important plant nutrients.

• Journal of Korean Society of Forest Science
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• v.95 no.3
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• pp.334-341
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• 2006

This study was to investigate the growth of planted red pine (Pinus densiflora S. et. Z.) seedling, soil properties and understory vegetation structure after fertilizer treatments [unfertilized plot (control), CF plot (Combination Fertilizer), UF plot (Urea Formaldehyde Fertilizer)] in a Pinus densiflora stand planted after the forest fires in Gosung, Gangwon province. The height growth rates of seedlings in four years were 264% in unfertilized, 404% in CF, and 388% in UF plots, respectively. The root collar diameters were increased 340% in unfertilized, 454% in CF, and 427% in UF plots, respectively. No significant changes occurred in soil total nitrogen and potassium ion ($K^+$) with the fertilization. However, available $P_2O_5$, content in the soil surface (0-15 cm) increased with the fertilizer application. Soil organic matter increased significantly with fertilizer treatments, while gradual decrease occurred in unfertilized plots. Sodium ion ($Na^-$) decreased in all sites. Soil pH, CEC, calcium ion ($Ca^{2+}$) and magnesium ion ($Mg^{2+}$) contents were not significantly different among treatments. Although Shannon's species diversity index and species richness in understory vegetation did not change with fertilizer treatments, vegetation cover rates in forest floor increased significantly with the fertilization. These results suggest that the increase of pine seedling growth and vegetation cover rates with fertilization could enhance soil stabilization in forest tire areas.

• The korean journal of orthodontics
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• v.27 no.5 s.64
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• pp.839-852
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• 1997

It has been submitted that different ion solutions containing sulfate induce crystal growth and might substitute conventional acid etching for pretreatment of enamel in orthodontic bonding(${\AA}rtun$ et al., Am. J. Orthod. 85, 333, 1984). This investigation was designed to evaluate the relevance of crystal growth on the enamel surface as an alternative to conventional acid etching in direct bonding of orthodontic brackets. Annexing Li2SO4, MgSO4, K2SO4 respectively in the solution with $25\%$ polyacrylic md 0.3M sulfuric acids were employed to enhance the crystal growth. Human bicuspids were treated with various parameters as combinations of crystal growth and glass ionomer cement, crystal growth and orthodontic resin, acid etching and orthodontic resin for an investigative purpose. Crystal growth solution containing MgSO4 showed the highest shear bond strength(15.6MPa) within the groups of bonding brackets with glass ionomer cement(p<0.01). Bonding with glass ionomer cement on the surface of crystal growth demonstrated higher shear bond strength than with orthodontic resin(p<0.001). Bonding with glass ionomer cement on the surface treated with crystal growth solution containing MgSO4 or K2SO4 was not different shear bond strength statistically from bonding with orthodontic resin on the acid-etched surface. It suggests that bonding brackets with glass ionomer cement on the surface treated with crystal growth solution containing MgSO4 or K2SO4 is a potential alternative to bonding with resin on the acid etched sufrace.

• Korean Journal of Soil Science and Fertilizer
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• v.7 no.4
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• pp.227-234
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• 1974

A survey on the vinyl house soils was conducted to investigate the salt accumulation status and it's effects on the deterioration of soil aggregates. The survey was made for the vinyl house soils in Suwon, Yesan, and Kimhae areas where vegetables are extensively grown under a vinyl house. Physical and chemical properties of the soils at the inside and outside of the vinyl house were compared to continuous vegetable cropping. Electrical conductivity of the soil solution (Y) in vinyl house was closely related to the number of cropping years (X), and the relations are given by the following regression equations: $Y=0.54X{\times}1.44$ ($r=0.580^*$) for loamy textured soils and $Y=0.58X{\times}2.61$ ($r=0.524^*$) for clayey textured soils. Electrical conductivity of the soils, where vegetable cropping in winter and rice in summer were rotated, was lower than that given by the regression equations. Analyses for extractable cations, the concentration of calcium, sodium and potassium was high in the inside vinyl house soils compared to the outside. Soil aggregates larger than 1mm in diameter were greatly deteriorated, while the content of the soil aggregates smaller than 0.5mm in diameter remained unchanged. Aggregate stability of the soil was negatively correlated to the accumulation rate of extractable sodium ($r=-0.681^{**}$), potassium ($r=-0.528^*$) and the amount of daily irrigated water (r=-0.477), while positively correlated to the content of organic matter ($r=-0.692^{**}$) and calcium (r=0.391).

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.75-82
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• 2010

Indoor cultivation plots for watermelon plant mostly have salt-accumulation problem because of continuous cropping especially with the heavy applications of chemical fertilizers. Thus, this study was conducted to investigate selected soil properties and watermelon growth condition as affected by the application of different farming practices in the salt-affected soils of greenhouse plots used for continuous watermelon production. Five different practice conditions in the experimental plots were applied, 1) a conventional farming practice (CFP), 2) a nitrogen-phosphorus-potassium (NPK) fertilizer management practice (FMP), and 3) the FMP with different amounts (5, 10, and 15 ton $ha^{-1}$)of fresh rice straw treatments (FMP-RS), for three years of study. As comparing with CFP plots, soil organic matter content gradually increased during the experimental years, whereas it decreased in the FMP only plot. Soil pH was not changed in the CFP and FMP plot, but it declined in the FMP-RS plots; however, it increased again from the third year in the FMP-RS plots with applying 10 and 15 ton $ha^{-1}$ of RS treatments. The concentrations of exchangeable cations, $Ca^{2+}$ and $Mg^{2+}$, except $K^+$, and water-soluble anions, ${NO_3}^-$, $Cl^-$, ${SO_4}^{2-}$ and ${PO_4}^{3-}$, markedly decreased in FMP and FMP-RS plots. In particular, the application of rice straw tended to significantly decrease the ion concentrations, especially most anions, in the first year, but there was no more decrease in the second and third study years. With relation to the ion concentrations, the changes of electrical conductivity (EC) after applying the management practices showed very similar to those of the ion concentrations. In addition, incidence of withered watermelon plant after applying the management practices dramatically declined from approximately 20% in the CFP plot to 3.5% in the FMP-RS plots. Water melon fruit weight was also improved by the management practices, especially FMP-RS. Therefore, the fertilizer and/or fresh rice straw application management practices are beneficial to improve salt-affected soils and watermelon plant growth condition.