• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.19-26
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• 2023

Hydrogen, a clean energy source free of COx emissions, is poised to replace fossil fuels, with its usage on the rise. Despite its high energy content per unit mass, hydrogen faces limitations in storage and transportation due to its low storage density and challenges in long-term storage. In contrast, ammonia offers a high storage capacity per unit volume and is relatively easy to liquefy, making it an attractive option for storing and transporting large volumes of hydrogen. While NH₃ decomposition is an endothermic reaction, achieving excellent low-temperature catalytic activity is essential for process efficiency and cost-effectiveness. The study examined the effects of different zeolite types (5A, NaY, ZSM5) on NH₃ decomposition activity, considering differences in pore structure, cations, and Si/Al-ratio. Notably, the 5A zeolite facilitated the high dispersion of Ni across the surface, inside pores, and within the structure. Its low Si/Al ratio contributed to abundant acidity, enhancing ammonia adsorption. Additionally, the presence of Na and Ca cations in the support created medium basic sites that improved N₂ desorption rates. As a result, among the prepared catalysts, the 15 wt%Ni/5A catalyst exhibited the highest NH₃ conversion and a high H₂ formation rate of 23.5 mmol/g_cat·min (30,000 mL/g_cat·h, 600 ℃). This performance was attributed to the strong metal-support interaction and the enhancement of N₂ desorption rates through the presence of medium basic sites.

• Economic and Environmental Geology
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• v.50 no.2
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• pp.171-180
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• 2017

This study performed the analysis on the volcanic gases and hot spring waters from the Julong hot spring at Mt. Baekdu during the period from July 2015 to August 2016. Also, we confirmed the errors that $HCO_3{^-}$ concentrations of hot spring waters in the previous study (Lee et al. 2014) and tried to improve the problem. Dissolved $CO_2$ in hot spring waters was analyzed using gas chromatograph in Lee et al. (2014). Improving this, from 2015, we used TOC-IC to analysis dissolved $CO_2$. Also, we analyzed the $Na_2CO_3$ standard solutions of different concentrations using GC, and confirmed the correlation between the analytical concentrations and the real concentrations. However, because the analytical results of Julong hot spring water were in discord with the estimated values based on this correlation, we can't estimate the $HCO_3{^-}$ concentrations of 2014 samples. During the period of study, $CO_2/CH_4$ in volcanic gases are gradually decreased, and this can be interpreted in two different ways. The first interpretation is that the conditions inside the volcanic edifice are changing into more reduction conditions, and carbon in volcanic gases become more favorable to distribute into $CH_4$ or CO than $CO_2$. The second interpretation is that the interaction between volcanic gases and water becomes greater than past, and the concentrations of $CO_2$ which have much higher solubility in water decreased, relatively. In general, the effect of scrubbing of volcanic gas is strengthened during the quiet periods of volcanic activity rather than active periods. Meanwhile, the analysis of hot spring waters was done on the anion of acidic gases species, the major cation, and some trace elements (As, Cd, Re).

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.605-615
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• 2012

Dance studies inherently have a nature of convergence and integration. Meanwhile, dance studies have extended their realm by investigating dance phenomena from many perspectives which art theories cannot explain. However, the previous and current dance studies are inadequate to explain a confluence society which is characterized as techuim, Interaction, freedom and openness according to the digital revolution. Hence, a result of research trend in domestic dance studies, it is found that dance studies have been studied in four perspectives since the early 2000s: first, a triggering the various studiesa of the convergent and integrative dance; second, an attempt to the convergent and integrative program development research; third, the vitalization of the convergent research on dance digital contents; and fourth, a research on the convergent dance art phenomena. These researches have played an important role in boosting a change in the structure and realm expansion of dance studies that are interdisciplinary research enabling a holistic approach to the integration and convergence between scientific technique, skills of dance art and other studies. However, it should be acknowledged that one problem is the current research development plan or/and research program have very little feasibility and practicality except an interdisciplinary research on the dance digital contents. Therefore, it is suggested for the development of dance studies in the age of convergence as follows: first, a dance convergent study integrated in skills and theories of dance and science that would pave the way for an academic foundation leading to a new humanistic model in the age of convergent; and second, a need for a paradigm shift that theories should be deployed in the scene on a commercial scale in order to produce effectiveness of the interdisciplinary and integrative research on dance studies by turning into a behavioristic research phase. third, it needs to changeover from large scale of convergent performance into small scale of convergent performance based on original idea for accumulation of teachnique research and promotion of dance convergent performance.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.3
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• pp.149-158
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• 2024

Purpose: This study aims to investigate the effects of provisional restoration fabrication methods and surface polishing on surface roughness and microbial adhesion through in vitro experiments. Materials and Methods: 120 cylindrical provisional restoration resin blocks (10 × 10 × 2.5 mm) were manufactured according to four fabrication methods, and 30 specimens were assigned to each group. Afterwards, they were divided into non-polishing group, #400 grit SiC polishing group, and #800 grit SiC polishing group and polished to a 10 × 10 × 2 mm specimen size (n = 10). The surface roughness Ra and Ry of the specimen was measured using a Surface Roughness Tester. Three specimens were extracted from each group and were coated with artificial saliva, and then Streptococcus mutans were cultured on the specimens at 37℃ for 4 hours. The cultured specimens were fixed to fixatives and photographed using a scanning electron microscope. For statistical analysis, the two way of ANOVA was performed for surface roughness Ra and Ry, respectively, and the surface roughness was tested post-mortem with a Scheffe test. Results: The fabrication method and the degree of surface polishing of the provisional restorations had a significant effect on both surface roughness Ra and Ry, and had an interaction effect. There was no significant difference in Ra and Ry values in all polishing groups in DLP and LCD groups. Conclusion: The fabrication method and surface polishing of the provisional restoration had a significant effect on surface roughness and showed different adhesion patterns for S. mutans adhesion.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.3
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• pp.151-157
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• 2015

Recent laboratory studies have documented that mixotrophic dinoflagellates Dinophysis spp. and heterotrophic dinoflagellate Oxyphysis oxytoxoides share a common prey, i.e. the mixotrophic ciliate Mesodinium rubrum. Nonetheless, very little is known about the population dynamics and species interactions among these protists in natural environments. To investigate the interactions between the dinoflagellate predators and their ciliate prey in the field, we took the samples twice a day from 26 July to 28 August, 2011 at a fixed station in Masan Bay and analyzed their abundances. During this study, salinity was highly variable, ranging from 5 to 28, due to the periodic input of rainfalls to the sampling station. Water temperature was on average $26.5^{\circ}C$ until 20 August and thereafter was about $21^{\circ}C$ by the end of the sampling period. The ciliate M. rubrum occurred persistently throughout the sampling period, ranging from 13 to $492\;cells\;mL^{-1}$. Cell densities of D. acuminata and O. oxytoxoides ranged from undetectable level to $19,833\;cells\;L^{-1}$ and from undetectable level to $100,333\;cells\;L^{-1}$, respectively. The high abundance of D. acuminata mostly followed the blooming of the ciliate M. rubrum, but it often did not peak even during heavy blooms of the prey, probably due to sensitivity to large salinity fluctuation and also presumably overlapped grazing by other mixotrophic dinoflagellates. The abundance of O. oxytoxoides was detected only when water temperature was lower than $24^{\circ}C$, indicating that water temperature is an important environmental factor to control the population dynamics of the dinoflagellate species.

• Fisheries and Aquatic Sciences
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• v.11 no.4
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• pp.183-189
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• 2008

In this study, tests were conducted to investigate the effects of three dietary growth hormones, administered in various amounts, on the growth performance and lysozyme activity in juvenile olive flounder, Paralichthys olivaceus. Three dietary growth hormones, recombinant human growth hormone (rHGH), recombinant bovine somatotropin A (rBST A) and recombinant bovine somatotropin B (rBST B) were tested at three different supplemental levels (10, 20 or 40 mg/kg body weight per week) by a $3{\times}3$ factorial design and a complete randomized design in comparison to a control group. Fish were fed one of the ten experimental diets (control, $rHGH_{10}$, $rHGH_{20}$, $rHGH_{40}$, rBST $A_{10}$, rBST $A_{20}$, rBST $A_{40}$, rBST $B_{10}$, rBST $B_{20}$ and rBST $B_{40}$) for 6 weeks and afterward were analyzed for growth performance by measuring weight gain (WG), feed efficiency (FE), specific growth rate (SGR) and protein efficiency ratio (PER). Based on the factorial design analysis, fish fed rHGH diets demonstrated significantly higher growth performance than fish fed rBST A or rBST B diets. However there were no significant differences in WG, FE, SGR and PER between fish fed rBST A and rBST B diets. Neither hormone level nor the interaction between the different hormones and their various levels had a significant effect on WG, FE, SGR, PER, lysozyme activity or whole-body proximate composition. A complete randomized design analysis confirmed fish fed $rHGH_{10}$, $rHGH_{20}$, $rHGH_{40}$, rBST $A_{10}$, rBST $A_{20}$, rBST $A_{40}$, rBST $B_{20}$ and rBST $B_{40}$ diets for 6 weeks showed higher WG than fish fed the control diet (P<0.05). A higher FE was observed in fish fed $rHGH_{10}$, $rHGH_{20}$, $rHGH_{40}$, rBST $A_{20}$ and rBST $A_{40}$ diets in comparison to fish fed the control diet. Fish fed all graded rHGH, rBST A and rBST B supplemented diets showed a higher SGR than fish fed the control diet. Regarding PER, fish fed $rHGH_{10}$, $rHGH_{20}$, $rHGH_{40}$, rBST $A_{10}$, rBST $A_{20}$, rBST $A_{40}$ and rBST $B_{20}$ diets were higher than fish fed the control diet. Furthermore, the lysozyme activity of fish fed a diet of $rHGH_{20}$ was significantly higher than that of fish fed any other diet. The results measuring the growth and development of the fish clearly suggest the biopotency of dietary rHGH could be higher than those of both dietary rBST A and rBST B. Further implied is the probability that within the range of 10 to 40 mg/kg BW/week the dietary growth hormones could accelerate growth performance, and that 20 mg rHGH/kg BW/week could possibly enhance lysozyme activity in juvenile olive flounder, Paralichthys olivaceus.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.291-297
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• 2013

The objective of this study was to know the growth response and light use efficiency of leaf lettuce (Lactuca sativa L.) 'Yorum Cheongchukmyeon' (green leaf lettuce) and 'Hongyom Jeokchukmyeon' (red leaf lettuce) under different RGB (Red:Green:Blue) ratio in a closed-type plant factory system. The plants were hydroponically cultured with a 12-h photoperiod at $20{\sim}25^{\circ}C$, 60~70% RH and 600~900 ${\mu}mol{\cdot}mol^{-1}$ $CO_2$. The light treatments were combined in three colors LEDs (red, blue, and white) and RGB ratios (1 : 4 : 5, 5 : 0 : 5, 5 : 2 : 3, 7 : 0 : 3, 7 : 1 : 2, and 8 : 1 : 1), however, as the light intensities of treatments were different. Growth characteristic response in both lettuces were significantly as affected by interaction between cultivar and light quality, when they were grown under different light quality conditions. Plant heights of green and red leaf lettuce were the lowest in 1 : 4 : 5 and 8 : 1 : 1, respectively. The highest length and number of leaf were showed 8 : 1 : 1 and 7 : 0 : 3 for the green and 5 : 2 : 3 and 8 : 1 : 1 for the red, respectively. Shoot dry weights of green and red leaf lettuce were the heaviest in 7 : 0 : 3 and 8 : 1 : 1, respectively. Leaf width and leaf shape index were significant about cultivar and light quality. Leaf widths of green and red leaf lettuce were the largest in 8 : 1 : 1 and 5 : 2 : 3, respectively. Leaf shape index of green and red leaf lettuce were the largest in 1 : 4 : 5 and 1 : 4 : 5, respectively. Shoot fresh weight and light use efficiency were significant about cultivar and light quality. Shoot fresh weights of green and red leaf lettuce were the heaviest in 7 : 0 : 3 and 8 : 1 : 1, respectively. Light use efficiencies of green and red leaf lettuce were the highest in 7 : 0 : 3 and 5 : 0 : 5, respectively. These results suggested that the ratio of RGB was 5~7 : 0~2 : 1~3 to cultivate leaf lettuce in a plant factory system.

• Journal of Animal Science and Technology
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• v.47 no.4
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• pp.593-606
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• 2005

Present study was conducted to investigate the optimal feeding levels for producing the high quality meat on the basis of the information deriving from the comparison of the growth performance and carcass characteristics among breeds(Holstein vs F1, Holstein♀×Hanwoo♂), sex(steer vs heifer) and interaction between breed and sex. Thirty two animals on 4 treatments(i.e. eight head each) were used for 540 days from seven to 24 months of age. The results obtained are summarized as follows; the range of average daily gains was 0.733 to 1.018, 0.994 to 1.255, 0.947 to 1.259 and 0.736 to 0.824kg for the growing, the early-fattening, the mid- fattening and the finishing periods, respectively. The range of average daily gains for the entire period was 0.882 to 1.061kg. The gains were higher for Holstein(7.3%) and the steers(10.5%) than F1 and the heifers, respectively. Concentrates and total digestible nutrients intakes per kg gain were higher for Holstein and the heifers than F1 and the steers, respectively. These findings may indicate that feed utilization is higher for Holstein than F1, and higher for the steers than the heifers. In carcass characteristics, back fat thickness was thicker for Holstein than F1, and rib-eye area was smaller for Holstein than F1. The rib-eye area per kg carcass weight was larger for F1 and the heifers than Holstein and the steers, respectively. Meat color was better for Holstein than F1, but the sex distinction did not show any differences. In physicochemical properties of longissimus dorsi, shear force, cooking loss, water holding capacity and the panel test scores of juiciness, tenderness and flavor for F1 and the heifers were better than those for Holstein and the steers, respectively. According to the above results, we may conclude that F1 and heifers rather than Holstein and steers are recommended for high quality meat production. In steers and heifers of Holstein and F1, the optimal feeding levels may be 1.9% of apparent body weight for concentrates and 25% of concentrates intake for rice straw.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.4
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• pp.42-51
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• 2020

This study was performed to support the 6th forest basic planning by Korea Forest Service as predicting the change of forestland area by the transition of land use type in the future over 35 years in South Korea. It is very important to analyze upcoming forestland area change for future forest planning because forestland plays a basic role to predict forest resources change for afforestation, production and management in the future. Therefore, the transitional interaction between land use types in future of South Korea was predicted in this study using econometrical models based on past trend data of land use type and related variables. The econometrical model based on maximum discounted profits theory for land use type determination was used to estimate total quantitative change by forestland, agricultural land and urban area at national scale using explanatory variables such as forestry value added, agricultural income and population during over 46 years. In result, it was analyzed that forestland area would decrease continuously at approximately 29,000 ha by 2027 while urban area increases in South Korea. However, it was predicted that the forestland area would be started to increase gradually at 170,000 ha by 2050 because urban area was reduced according to population decrement from 2032 in South Korea. We could find out that the increment of forestland would be attributed to social problems such as urban hollowing and localities extinction phenomenon by steep decrement of population from 2032. The decrement and increment of forestland by unbalanced population immigration to major cities and migration to localities might cause many social and economic problems against national sustainable development, so that future strategies and policies for forestland should be established considering such future change trends of land use type for balanced development and reasonable forestland use and conservation.

• Journal of the Korean Chemical Society
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• v.37 no.2
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• pp.237-243
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• 1993

The primary and secondary structure of the 5S rRNA isolated from Xanthomonas celebensis were determined by enzymatic and chemical degradation methods. It consists of 119 nucleotides and contains no modified nucleosides. As with the 5S rRNAs of X. maltophilia and X. citri, it contains an additional uridine residue on the 5'-terminus. Its secondary structure was almost identical to the models previously proposed by us for the 5S rRNA of two Xanthomonas species. Its secondary structure consists of five helices, five loops and two bulges. The tertiary interactions in the 5S rRNA molecule were analyzed by Fe(II)-EDTA treatment and hybridization method using deoxyhexamer. From the fact that some adenine residues in loop M, region $I_1-C$, loop $H_1$, and loop $H_2$ become susceptible to diethylpyrocarbonate when the 5S rRNA was hybridized with deoxyhexamer complementary to the sequence $U_{35}CCCAU_{40}$ and that some nucleotide residues in loop M, loop $H_1$ and region $D-I_2$ become resistant Fe(II)-EDTA cleavage in the presence of $Mg^{2+}$, it is presumed that loops $H_1$ and $H_2$ interact with loop M in some way. In the tertiary interaction, the regions $I_1-C$ and $D-I_2$ seem to act as hinges in folding the stems $B-I_1-C$ and $D-I_2-E.$ It was found that loop $H_1$ changes into a smaller loop of three bases by forming noncanonical A : C base-pairs ih acidic environment.