• Journal of the Korean Society of Earth Science Education
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• v.15 no.2
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• pp.224-234
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• 2022

The purpose of this study was to analyze STEAM elements and convergence types that appeared in the creative and convergent activities in elementary school science textbooks, which were converted from the national issuance system to the authorized system in 2022. For this study, 6 elementary school science textbooks for 3rd and 4th graders were selected. And STEAM elements in creative and convergent activities were analyzed by publishers, grade-semesters, and science fields, and the convergence type was analyzed for each publisher. The results of this study are as follows. First, the total frequencies of STEAM elements and the ratios of each element in the creative and convergent activities of textbooks were different for each publisher. However, among the four elements except for science (S) element in all publishers, the tendency to have a high proportion of art (A) element and a very low proportion of mathematics (M) element was common. Second, the higher the number of fused STEAM elements, the lower the rate of appearance in the textbooks in overall. Also the ratio of convergence types of STEAM elements varied by each publisher. Third, the ratio deviations of art (A), technology (T), and engineering (E) elements for each grade-semester were not large, but the ratio deviation of the mathematics (M) element was large. Fourth, technology (T) and engineering (E) elements appeared a lot in the fields of 'movement and energy' and 'material', while art (A) element appeared a lot in the fields of 'earth and universe', 'life', and 'integration'.

• Journal of the Korean Society of Earth Science Education
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• v.16 no.2
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• pp.291-301
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• 2023

In this study, the STEAM elements and convergence types which appeared in the creative and convergent activities in authorized elementary school science textbooks for 5^th and 6^th graders were analyzed. For this study, creative and convergence activities presented in 9 different science textbooks for 5^th and 6^th graders were selected and the STEAM elements and convergence types were analyzed by each publisher, grade-semester, and science field. The results of this study are as follows. First, there was a large variation by publisher in the total frequency of STEAM elements and the frequency of each element in creative and convergence activities. Second, the ratio of convergence type consisting of two elements was very high, and the higher the number of fused elements, the lower the ratio appeared in overall. Third, the art (A) element had the highest frequency in all grade-semesters, and the technology (T), engineering (E), mathematics (M) elements differed in the distribution of frequency by grade-semesters. Fourth, the engineering (E) element in the 'integration' field, and the art (A) element in the fields of 'movement and energy', 'material', 'earth and universe', and 'life' had the highest frequency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5B
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• pp.447-457
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• 2006

This paper presents a numerical model for the simulations of 2D depth-averaged flows. The shallow water equations are solved numerically by the Characteristic Dissipative Galerkin (CDG) finite element method. For validation, the developed model is applied to the hydraulic jump. The computed results are compared with the analytical solution, revealing good agreement. In addition, flow in a contracting channel showing standing waves is simulated. The calculated water surface profile appears to be qualitatively consistent with the observed data. The foregoing results indicate that the model is capable of simulating the abrupt change in flow field. Next, the model is applied to the flow in a $180^{\circ}$ curved channel. The simulated results show that the velocity near the inner bank is faster than that near the outer bank and the water depth near the inner bank is shallower than that near the outer bank. However, the simulated results show that the velocity distribution across the channel is almost uniform in the bend except the reach close to the end of the bend. This is due to the limitation of the governing equations in which the transverse convection of momentum by the secondary flows along a channel bend is not taken into account.

• Korean Chemical Engineering Research
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• v.62 no.3
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• pp.238-245
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• 2024

The lactate electrode can be utilized either as an electrode for lactate sensor to monitor the patient's health status, stress level, and athlete's fatigue in real time or lactate fuel cell. In this study, we fabricated a high-performance electrode composed of lactate oxidase, catalase, and mitochondria, and investigated the surface analysis and electrochemical properties of this electrode. Carbon paper modified with single-walled carbon nanotubes (CP-SWCNT) had significantly improved electrical conductivity compared to before modification. The electrode to which lactate oxidase, catalase, and mitochondria were attached (CP-SWCNT-LOx-Cat-Mito) produced a higher current than the electrode to which lactate oxidase and catalase were attached. The amount of reduction current produced by the bilirubin oxidase (BOD)-attached electrode (CP-SWCNT-BOD) was greatly affected by the presence or absence of oxygen in the electrolyte. The fuel cell composed of CP-SWCNT-LOx-Cat-Mito (anode) and CP-SWCNT-BOD (cathode) produced maximum power (29 ㎼/cm²) at a discharge current density of 133 ㎂/cm². From this study, we had proved that mitochondria is essential for improving lactate sensor and fuel cell performance.

• Korean Journal of Poultry Science
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• v.42 no.2
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• pp.109-116
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• 2015

Ogye rooster sperm chromatin status can be detected using well established sperm assays. In this paper, a simple and fast method to monitor rooster sperm chromatin status could be employed in field for assessment of chicken sperm quality. Using standard bright field microscope, Diff-Quik stains can be reproducibly, easily and routinely monitored with simple staining. The presence of abnormal chromatin staining of rooster sperm was determined by darker stain in head. In the fresh semen, the viabilities of three tested Ogye spermatozoa were 93.53%, 82.42% and 90.63% and normal chromatin rates were 87.96%, 74.25% and 85.10% respectively. However, after freezing, the rates of viability of thawed semen were reduced to 69.58%, 61.98% and 72.20% and normal chromatin rate also reduced to 58.91%, 48.49% and 63.34%. A significant correlation between live sperm and normal sperm nuclei was 0.875 in fresh semen and 0.513 in frozen semen. After incubation of sperm at $37^{\circ}C$ for 5min, the rates of viability, chromatin normality and sperm head activity were shown as $90.63{\pm}1.28%$, $82.44{\pm}8.09%$ and $66.68{\pm}10.29%$ in fresh semen. However, the rates of thawed semen were reduced to $67.92{\pm}7.55%$, $56.92{\pm}12.15%$ and 47.32{\pm}5.02%, respectively. The relationship between chromatin normality and sperm head movements in fresh and thawed semen were 0.564 and 0.540, respectively. With these results, the chicken sperm normality could be assessed by the Diff-Quik staining that could be used for chromatin status of sperm head and activated morphology of live spermatozoa, as a simple and rapid staining method.

• The Korean Journal of Pharmacology
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• v.10 no.1 s.15
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• pp.31-40
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• 1974

1. The authors investigated the effects of $PGE_1$ on the action of sympathomimetics in the vas deferens of guinea-pig, comparing with those in the rat vas deferens, and also the action of $PGE_1$ on the motility of nerve-free smooth muscle of chick amnion. 2. In the isolated guinea-pig vas deferens, the actions of phenylephrine and norepinephrine were much potentiated by pretreatment with $PGE_1$. Futher, in the isolated hypogastric nerve-vas deferens preparation of guinea-pig, effects of phenylephrine, norepinephrine and tyramine on the contractile response of vas to the hypogastric nerve stimulation and to the transmural stimulation were also augumented especially in tension by $PGE_1$-pretreatment. 3. In the isolated hypogastric nerve-vas preparation of rat, both contractile responses to hypogastric nerve and transmural stimulation were slowly reduced by treatment with $PGE_1$ and the potentiated effect of phenylephrine or norepinephrine was not observed in spite of pretreatment with $PGE_1$. 4. The actions of phenylephrine and norepinephrine on the denervated vas deferens of guinea-pig were also enhanced by $PGE_1$ as it were in the intact vas deferens, but there was no significant effect by $PGE_1$ on the action of norepinephrine in the denervated rat vas deferens. 5. $PGE_1$ in low concentration $(10^{-8}g/ml)$ did not affect the spontaneous motility of nerve-free smooth muscle of chick amnion ($9{\sim}11$ th day incubated chick), but in large concentration $(5{\times}10^{-8}g/ml)$ it caused irregular and slightly inhibitory movement. Pretreatment with $PGE_1$ on chick amnion did not exert any change on the action of phenylephrine applied. However, the stimulatory action of physostigmine on the chick amnion was a little antagonized by the low concentration of $PGE_1$. 6. It might be summarized that there is species difference between the actions of $PGE_1$ on the vas deferens of guinea-pig and that of rat, and the action of $PGE_1$ on the guinea-pig vas deferens might be mediated by the other mechanism rather than by direct action on the vas musculature.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.2
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• pp.138-148
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• 2022

The 1920s and 1930s were when new trends became prominent in Korean housing architecture. This study began with a curiosity about the appearance of residential gardens during the transition period, when housing types were changing. Since gardens are constantly evolving and living spaces, it is not easy to give a clear picture of their evolution. However, through popular magazines and newspaper articles published in the 1920-30s, this study investigated how people perceived the gardens socially and how they engaged in gardening. First, the study of Gyeongseong's urbanization process revealed that people perceived gardens as a way to give natural beauty to the urban environment. Therefore, the creation of a residential garden was strongly encouraged. Second, the housing improvement movement, which the architects actively discussed during this period, emphasized that a garden is a factor that can help improve the quality of the residential environment in terms of hygiene and landscape aesthetics. Third, since the media provided information on gardening, it was confirmed that the number of people engaged in gardening as a hobby increased. As designers and gardeners who had received a modern education became more active, the concept of "designed gardens" was formed. Lastly, although the houses were divided into various types, the shapes of the gardens did not show a significant difference according to the architecture type. They tended to embrace the time's ideal garden design and style. Therefore, even in a traditional hanok, Western-style gardens were naturally harmonized into the overall architecture, and exotic plant species could be found. Although the gardens found in media images were limited to those belonging to the homes of the intelligentsia, it can be seen that representativeness was secured, considering the popularity and ripple effect of the media. Therefore, this study contributes to the literature as it confirmed the ideal gardens and gardening methods in the 1920s and 30s.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.10
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• pp.1406-1413
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• 2016

This study was carried out to evaluate the toxicity of ethanolic extracts of Morus alba L. branch (ME). In the reverse mutation test, Salmonella Typhimurium TA98, TA100, TA1535, TA1357, and Escherichia coli WP2uvrA were used to estimate the mutagenic potential of ME. Sprague-Dawley rats were orally administered ME at levels of 1,250, 2,500, and 5,000 mg/kg for the single-dose toxicity test and 500, 1,000, and 2,000 mg/kg/d for the repeated-dose toxicity test for 28 consecutive days. As expected, reverse mutation was not detected at any concentration of ME, regardless of application of the metabolic activation system with or without S9 mix. In the single-dose toxicity test, ME caused neither significant visible signs of toxicity nor mortality in rats, and $LD_{50}$ was estimated to be over 5,000 mg/kg. In the repeated-dose toxicity test, ME administration at 500, 1,000, and 2,000 mg/kg for 28 days to male or female rats did not result in mortality. Similarly, no toxicologically significant treatment-related changes in body weight, food intake, or organ weights were noted. Several hematological and biochemical parameters in both genders showed significant differences, but these were within normal ranges. These results support the safe use of ME.

• Economic and Environmental Geology
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• v.22 no.4
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• pp.303-314
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• 1989

The electrum-silver-sulfide mineralization of the Geojae island area was deposited in three stages (I, II, and carbonate) of quartz and calcite veins that crosscut Late Cretaceous volcanic rocks and granodiorite(83 m.y.). Stages I and II were terminated by the onset of fractunng and breCCIation events. Fluid inclusion data suggest that the gold-sulfide-bearing stages I and II each evolved from an initial high temperature( near $370^{\circ}C$) to a later low temperature(near $200^{\circ}C$). Each of those stages represented a separate mineralizing system which cooled prior to the onset of the next stage. The relationship between homogenization temperature and salinity in stages I and II suggests a complex history of boiling, cooling and dilution. Evidence of boiling indicates a pressure of < 100 bars, corresponding to a depth of 500 to 1,250m assummg hthostatlc and hydrostatic pressure regimes, respectively. Fluid inclusion and mineralogical evidence suggest that the electrum-silver mineralization was deposited at a temperature of $220-260^{\circ}C$ from ore fluids with salinities between 1.9 and 8.1 equivalent wt.% NaCl. Total sulfur concentration is estimated to be $10^{-3}$ to $10^{-4}$ molal. The estimated $fs_2$ and $fo_2$ range from $10^{-11.8}$ to $10^{-14}$ atm and $10^{-35}$ to $10^{-36}$ atm, respectively. The chemical conditions indicate that the dominant sulfur species in the ore forming fluids was a reduced form($H_2S$). Rapid cooling and dilution of ore-forming fluids by mixing with less-evolved meteoric waters led to gold-silver deposition through the breakdown of the bisulfide complex($Au(HS)_2$) as the activity of $H_2S$ decreased.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.3
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• pp.140-147
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• 2002

We investigated the temporal variations in the heterotrophic dinoflagellates (hereafter HTD), tintinnid ciliates(TC), and naked ciliates(NC) from August to November 1999 in the coastal waters off the southern Saemankeum areas where a huge red tide dominated by Cochlodinium polykrikoides/Gymnodinium impudicum was first observed in 1998. We took water samples from 2-5 depths of 4 stations in each of the 5 cruises and then measured the species composition and abundances of HTD, TC, and NC The maximum species numbers and densities of HTD, TC, and NC(11, 12, and 10 cells $m\ell$$^{-1}$ , respectively) were observed when the density of diatoms was highest (August 10), while the lowest values (1.0, 0.5, and 2.4 cells $m\ell$$^{-1}$ , respectively) were found when the red tide dominated by C. polykrikoides/G. impudicum took placed (October 18). On August 10 and November 11 when diatoms dominated the abundance of phytoplankton, the correlation coefficients between TC, NC and diatoms were relatively high. However, On September 16 and October 18 when autotrophic+mixotrophic dinoflagellates(ATD+MTD) were abundant, the correlation coefficients between HTD and ATD+MTD were relatively high. The large HTD Noctiluca scintillans was the most dominant heterotrophic protists during the C. polykrikoides/G. impudicum red tide on October 18. N. scintillans has been known to feed on the prey cells when the swimming speeds of C. polykrikikoides/G. impudicum markedly reduced at the decline stage of the red tide. Therefore, N. scintillans could be effective grazers on C. polykrikoides/G. impudicum. The maximum densities of HTD, TC, and NC in the study area were fairly lower than those obtained in the waters off Kohung-Yeosu areas in the summer-fall, 1997. The results of the present study provide the basis of understanding predator-prey relationships between dominant phytoplankton and heterotrophic protists and the roles of the protist grazers in bloom dynamics in the waters off the western Korea.