• Journal of The Korean Astronomical Society
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• v.36 no.4
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• pp.271-282
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• 2003

We present results of a $H^{13}CN$ J=1-0 mapping survey of molecular clouds toward the Galactic Center (GC) region of $-1.6^{\circ}{\le}{\iota}{\le}2^{\circ}$ and $-0.23^{\circ}{\le}b{\le}0.30^{\circ}$ with 2' grid resolution. The $H^{13}CN$ emissions show similar distribution and velocity structures to those of the $H^{12}CN$ emissions, but are found to better trace the feature saturated with $H^{12}CN$ (1-0). The bright components among multi-components of $H^{12}CN$ line profiles usually appear in the $H^{13}CN$ line while most of the dynamically forbidden, weak $H^{12}CN$ components are seldom detected in the $H^{13}CN$ line. We also present results of other complementary observations in $^{12}CO$ (J=1-0) and $^{13}CO$ (J=1-0) lines to estimate physical quantities of the GC clouds, such as fractional abundance of HCN isotopes and mass of the GC cloud complexes. We confirm that the GC has very rich chemistry. The overall fractional abundance of $H^{12}CN$ and $H^{13}CN$ relative to $H_2$ in the GC region is found to be significantly higher than those of any other regions, such as star forming region and dark cloud. Especially cloud complexes nearer to the GC tend to have various higher abundance of HCN. Total mass of the HCN molecular clouds within $[{\iota}]{\le}6^{\circ}$ is estimated to be ${\~}2 {\times}10^7\;M_{\bigodot}$ using the abundances of HCN isotopes, which is fairly consistent with previous other estimates. Masses of four main complexes in the GC range from a few $10^5$ to ${\~}10^7\;M_{\bigodot}$ All the HCN spectra with multi-components for the four main cloud complexes were investigated to compare the line widths of the complexes. The largest mode (45 km $s^{-1}$) of the FWHM distributions among the complexes is in the Clump 2. The value of the mode tends to be smaller at the farther complexes from the GC.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.77-77
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• 2016

Thin films synthesized by plasma processes have been widely applied in a variety of industrial sectors. The structure control of thin film is one of prime factor in most of these applications. It is well known that the structure of this film is closely associated with plasma parameters and species of plasma which are electrons, ions, radical and neutrals in plasma processes. However the precise control of structure by plasma process is still limited due to inherent complexity, reproducibility and control problems in practical implementation of plasma processing. Therefore the study on the fundamental physical properties that govern the plasmas becomes more crucial for molecular scale control of film structure and corresponding properties for new generation nano scale film materials development and application. The thin films are formed through nucleation and growth stages during thin film depostion. Such stages involve adsorption, surface diffusion, chemical binding and other atomic processes at surfaces. This requires identification, determination and quantification of the surface activity of the species in the plasma. Specifically, the ions and neutrals have kinetic energies ranging from ~ thermal up to tens of eV, which are generated by electron impact of the polyatomic precursor, gas phase reaction, and interactions with the substrate and reactor walls. The present work highlights these aspects for the controlled and low-temperature plasma enhanced chemical vapour disposition (PECVD) of Si-based films like crystalline Si (c-Si), Si-quantum dot, and sputtered crystalline C by the design and control of radicals, plasmas and the deposition energy. Additionally, there is growing demand on the low-temperature deposition process with low hydrogen content by PECVD. The deposition temperature can be reduced significantly by utilizing alternative plasma concepts to lower the reaction activation energy. Evolution in this area continues and has recently produced solutions by increasing the plasma excitation frequency from radio frequency to ultra high frequency (UHF) and in the range of microwave. In this sense, the necessity of dedicated experimental studies, diagnostics and computer modelling of process plasmas to quantify the effect of the unique chemistry and structure of the growing film by radical and plasma control is realized. Different low-temperature PECVD processes using RF, UHF, and RF/UHF hybrid plasmas along with magnetron sputtering plasmas are investigated using numerous diagnostics and film analysis tools. The broad outlook of this work also outlines some of the 'Grand Scientific Challenges' to which significant contributions from plasma nanoscience-related research can be foreseen.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.1047-1050
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• 2010

This study was to investigate the effects of rice straw incorporation by cutting height on paddy soil fertility. The average residual amount of rice straw by cutting height were showed 1,420 kg $ha^{-1}$, 1,850 kg $ha^{-1}$, and 2,400 kg $ha^{-1}$ for depths of 10 cm, 15 cm, and 20 cm, respectively. For soil physical properties, soil hardness and bulk density were decreased while porosity was increased by rice straw incorporation. But soil organic matter (SOM), available silicate content, and cation exchange capacity (CEC) were significantly decreased when rice straw was removed from the field. These results indicated that the SOM as residual amount of rice straw was influenced by level of cutting height. Milled rice yield was increased by 28% and 32% for cutting heights of 15 cm and 20 cm, compared with that of control, respectively. The number of spikelets per square meter and the percentage of ripeness were increased with increasing incorporation by lower level of cutting height of rice straw. Therefore, incorporation of rice straw practices under cutting method influenced soil improvement and rice yield in paddy field.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.595-601
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• 2014

The microstructures of NATM were examined by SEM, FT-IR spectra, tensile properties, mole % of [NCO/OH], and particle size analyzer. Growing concerns in the environment-friendly industries have led to the development of solvent-free formulations that can be cured. We had synthesized NATM(New Austria Tunnel Method) resin having the ability to protect stainless steel against corrosion. Comparing with general NATM resin and coatings, this resin that synthesized with polyurethane and epoxy was highly stronger in intensity and longer durability. Hybrid resin was composed of polyols, MDI, epoxy, silicone surfactant, catalyst and crosslink agent, and fillers. Moreover, fillers such as fume silica not only accelerated the curing rate but also improved the physical property as thermal barriers. The rigid segments of synthetic resin in mechanical properties were due to fume silica and the increase the mole% of [NCO/OH] for corrosion protection. In conclusion, the hybrid resin microstructure with crosslink agent and fume silica are good material for thermosetting coating of metal substrates such as stainless steel.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.532-539
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• 2011

The physical and chemical properties of the dried low rank coals (LRCs) before and after the surface treatment using ozone and ammonia were characterized in this study. The contents of moisture, volatiles, fixed carbon and ash consisting of dried LRCs before the surface treatment were about 2.0, 44.8, 44.9 and 8.9%, respectively. Also, it was composed of carbon of 62.66%, hydrogen of 4.33%, nitrogen of 0.94%, oxygen of 27.01% and sulfur of 0.09%. The dried LRCs was surface-treated with the various dry methods using gases such as ozone at room temperature, ammonia at $200^{\circ}C$ and then the dried LRCs before and after the surface treatment were characterized by the various analysis methods such as FT-IR, TGA, proximate and elemental analysis, caloric value, ignition test, adsorption of $H_2O$ and $NH_3-TPD$. As a result, the oxygen content increased and the calorific value, ignition temperature and the contents of carbon and hydrogen relatively decreased because the oxygen-contained functional groups were additionally generated by the surface oxidation with ozone which plays a role as an oxidant. Also, its $H_2O$ adsorption ability got higher because the hydrophilic oxygen-contained functional groups were additionally generated by the surface oxidation with ozone. On the other hand, it was confirmed that the dried LRCs after the surface treatment with $NH_3$ at $200^{\circ}C$ have the decreased oxygen content, but the increased calorific value, ignition temperature and contents of carbon and hydrogen because of the decomposition of oxygen-contained functional groups the on the surface. In addition, the $H_2O$ adsorption ability was lowered bucause the surface of the dried LRCs might be hydrophobicized by the loss of the hydrophilic oxygen-contained functional groups. It was concluded that the various physico-chemical properties of the dried LRCs can be changed by the surface treatment.

• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.266-274
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• 2014

To extend the understanding of the pyrolysis mechanism of wood, we have investigated wood dust charcoal and condensate of volatile organic compounds (VOC) obtained during the pyrolysis of red pine (Pinus densiflora Sieb. et Zucc.) at $180{\sim}450^{\circ}C$ using elemental analysis, IR and GC/Mass. The effect of activation process on the charcoal structure also has been studied by comparing elemental analysis and IR data of charcoal carbonated at $600^{\circ}C$ and charcoals activated at $750^{\circ}C$. The results show that pyrolysis of wood has mainly started near at $240^{\circ}C$ and its chemical components did not changed much up to $270^{\circ}C$. However, the element contents and IR spectra drastically changed at $300^{\circ}C$. The fact that IR peaks related to the aromatic ring of lignin are observed in the charcoal pyrolized at $450^{\circ}C$ indicates that a small part of lignin still remains at this temperature. The chemical structure of the activated charcoal seems almost unaffected by the activation time.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.901-908
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• 2018

Graphite is used as a sample anode active material. However, since the maximum theoretical capacity is limited to $372mA\;h\;g^{-1}$, a new anode active material is required for the development of a high capacity lithium ion battery. The maximum theoretical capacity of Si is $4200mA\;h\;g^{-1}$, which is higher than that of graphite. However, it is not suitable for direct application to the anode active material because it has a volume expansion of 400%. In order to minimize the decrease of the discharge capacity due to the volume expansion, the Si was pulverized by the dry method to reduce the mechanical stress and the volume change of the reaction phase, and the change of the volume was suppressed by coating the carbon layers to the particle size controlled Si particles. And carbon fiber is grown like a thread on the particle surface to control secondary volume expansion and improve electrical conductivity. The physical and chemical properties of the materials were measured by XRD, SEM and TEM, and their electrochemical properties were evaluated. In this study, we have investigated the synthesis method that can be used as anode active material by improving cycle characteristics of Si.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.117-123
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• 2021

In this study, the composite was prepared by mixing SiOx, soft carbon, and carbon black and the electrochemical properties of lithium ion battery were investigated. The content of SiOx added to improve the capacity of the soft carbon anode material was varied to 0, 6, 8, 10, 20 wt%, and carbon black was added as a structural stabilizer for reducing the volume expansion of SiOx. The physical properties of prepared CB/SiOx/C composite were investigated through XRD, SEM, EDS and powder resistance analysis. In addition, the electrochemical properties of prepared composite were observed through the charge/discharge capacity, rate and impedance analysis of the lithium ion battery. The prepared CB/SiOx/C composite had an inner cavity capable of mitigating the volume expansion of SiOx by adding carbon black. The formed internal cavity showed a low initial efficiency when the SiOx content was less than 8 wt%, and low cycle stability when the content of SiOx was less than 20 wt%. The CB/SiOx/C composite containing 10 wt% of SiOx showed an initial discharge capacity of 537 mAh/g, a capacity retention rate of 88%, and a rate of 79 at 2C/0.1C. SiOx was added to improve the capacity of the soft carbon anode material, and carbon black was added as a structural stabilizer to buffer the volume change of SiOx. In order to use the CB/SiOx/C composite as a high-efficiency anode material, the mechanism of the optimal SiOx and the use of carbon black as a structural stabilizer was discussed.

• Applied Biological Chemistry
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• v.22 no.2
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• pp.123-134
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• 1979

For the purpose of developing a microbial insecticide utilizing Bacillus thuringiensis Berliner, research was done and the following results were obtained. 1) As the freeze-dried matter of the cocoon-cooked water discarded from the filature contains much crude protein(51.825%) and a lot of inorganic salts, it can make a good nutrition source for the culture cf B. thuringiensis Berliner. 2) Based on the suspensibility, formula F-5 turned out to be the most suitable for insecticidal use. Its composition includes 0.2 g of the cell-spore-crystal mixture, 25 g of 200-mesh kaolin, 2.5 g of New Kalgen-NX-150, and 2.5 g of glycerine admixed with 8 ml of distilled water and granulated in 80-mesh size. 3) All the components of F-5, F-6 and F-7 are identical except that the amounts of cell-spore-crystal mixture of F-5, F-6, and F-7 are 0.2 g, 0.4 g, and 0.6 g, respectively. Accordingly, their physical properties are almost all the same. 4) Formulas F-5, F-6, and F-7 exhibited an excellent toxicity to Anomis mesogona Walker, Dendrolimus spectabilis Butler, and Margaronia perspectalis Walker at the concentration of 5%. 5) Formulas F-8 and F-9 which contain $NaHCO_3$ as one of their components showed a remarkably reduced toxicity to Anomis mesogona Walker and Dendrolimus spectabilis Butler than F-6 which does not contain $NaHCO_3$. 6) A maximum of $2.97{\times}10^9$ spores per ml was obtained by incubating B. thuringiensis in M-3 which has a pH of 7.05 and comprises 0.2% of ammonium sulphate and 0.8% of glucose dissolved in the cocoon-cooked water, with aeration for 96 hours. 7) Formula F-6 exhibited a somewhat reduced toxicity to Anomis mesogona Walker and Dendrolimus spectabilis Butler, when stored at room temperature for 70 days after formulation and it is desirable to keep it in a dark and cold place. 8) In held applications, formula F-6 showed a good activity in controlling Monema flavescens Walker. Margaronia perspectalis Walker, and Macrosiphum ibarae Matsumura.

• Applied Biological Chemistry
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• v.28 no.2
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• pp.68-75
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• 1985

Laboratory experiments were conducted to investigate the effect of compost and humic acid treatment on adsorption of Cd, Zn, and Cu in soils. Three soils differing in physical and chemical properties used in this experiments were Bonyrang (Typic Udifluvents) SL, Gangseo (Aquatic Eutrochrepts) L, and Gyorae (Typic Distrandepts) SiL. Adsorption of Cd, Zn, ana Cu on the soils followed Langmuir isotherm up to 75 ppm of initial concentration. The adsorption maxima of Cd, Zn, and Cu for the Bonryang soil, the lowest in pH, organic matter content, and CEC, were the lowest of the three soils. Although the Gyorae soil derived from volcanic ash was the highest in organic matter content and CEC, the adsorption maxima of heavy metals for the Gyorae soil were lower than those for the Gangseo soil of which organic content and CEC were intermidiate. The adsorption maxima/CEC ratios for the Bonryang, the Gangseo, the Gyorae soils were found to be in the range of $23{\sim}27%,\;28{\sim}57%$, and $11{\sim}14%$ respectively The bonding energy constants of Cd, Zn, and Cu for the soils were in the order of Gangseo>Bonryang>Gyorae soils. The adsorption maxima of Cd, Zu, and Cu for the Bonryang soil increased with compost treatment by $100{\sim}210%,\;90{\sim}230%$, and $130{\sim}290%$ respectively, while little difference was observed when the soil was treated with humic acid Bonding energy constants of Cd, Zn, and Cu for the Bonryang soil increased significantly with compost treatment, and showed insignificant correlation with humic acid treatment.