• Ocean and Polar Research
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• v.41 no.4
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• pp.275-288
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• 2019

We investigated flux, grain size distribution, Nd-Sr isotope composition, mineral composition, and trace metal composition (REEs and Sc) of inorganic silicate fraction (ISF, mainly Asian dust with an unrestricted amount of volcanic materials) deposited during 600~1000 ka across the Mid-Pleistocene Transition at core NPGP 1401-2A (32°01'N, 178°59'E, 5205m) taken from the central part of the North Pacific. Our results reveal about a 2-fold increase in ISF flux after 800 ka, which is associated with an increase in La/Sc and a decrease in mean grain size. Asian dusts are finer than volcanic materials and La/Sc increases with the enhanced contribution of Asian dusts. Thus, increased flux after 800 ka can be explained by the increased contribution of Asian dusts relative to volcanic materials, likely due to an intensified Westerly Jet (WJ) and the drying of the Asian continent after the MPT. Mean grain size of ISF varies systematically in relation to glacial-interglacial cycles with a decrease during glacial stages, which is consistent with the previous results in the study area. Such a cyclical pattern is also attributed to the increase in the relative contribution of Asian dusts over volcanic components in glacial stages due to intensified WJ and drying of the Asian continent. Thus, it can be concluded that climate changes that had occurred across the MPT were similar to those of interglacial to glacial transitions at least in terms of the dust budget. Different from the Shatsky Rise, however, compositional changes associated with glacial-interglacial mean grain size fluctuations are not observed in Nd-Sr isotope ratios and trace element composition in our study of the Hess Rise. This may be attributed to the location of the study site far (> 4,000 km) from the volcanic sources. The volcanic component at the study site comprises less than 10% and varies within 3% over glacial-interglacial cycles. Such a small variation was not enough to imprint geochemical signals.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.4
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• pp.179-195
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• 2004

The trophic state of the coastal waters of the southern part of Korea was assessed using biogeochemical data obtained from the National Marine Environmental Monitoring Program conducted by the National Fisheries Research and Development Institute for six years. The trophic state of different areas, analyzed by non-metric multi-dimensional scaling (MDS) analysis, could divide the areas into three groups. Masan Bay, with suboxic water masses and/or the highest concentrations of dissolved inorganic nitrogen and phosphorus occurred, was assessed as being in a hypertrophic state. Ulsan Bay, Onsan Bay, Busan and Jinhae Bay, located near strong point sources, were in a eutrophic state. Other areas, including Tongyong, Yosu, Mokpo and Jeju island, were evaluated as being in a mesotrophic state. During 1997 to 2002, the average values of excess nitrogen, which is the difference between the measured dissolved inorganic nitrogen (DIN) and the corrected DIN using the Redfield ratio, were positive at Ulsan, Onsan, and Busan, where there were inflows from polluted rivers. In contrast, those were negative values in Haengam Bay, Gwangyang Bay and nearby Yosu. This suggests that the limiting element for phytoplankton growth differed among sites. The time series data of excess nitrogen showed gradual decrease over time in the hypertrophic waters, but the opposite trend in the mesotrophic waters. This indicated that the ratio of nitrogen to phosphate varied according to the trophic state of the coastal waters. The enrichment of organic matter in sediment in eutrophic waters would disturb the normal pattern of biogeochemical cycling of nitrogen and phosphate. In order to assess the condition of the coastal environment, the benthic boundary layer should be considered.

• Journal of Bio-Environment Control
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• v.30 no.3
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• pp.244-249
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• 2021

The hydroponic culture for growing 'Duke' blueberry was evaluated in a protective greenhouse provided with similar environmental conditions to the conventional blueberry cultivations. One year old 'Duke' blueberry bushes planted in 180 L containers filled with 130 L peat moss and 40 L pearlite (v/v) were selected for the experiment. A nutrient solution consisted with NO₃-N 4.6, NH₄-N 3.4, PO₄-P 3.3, K 3, Ca 4.6, and Mg 2.2 mmol^-1 was supplied to the plants, comparing non-hydroponic treatment (provided with only underground water). Hydroponic culture increased number of shoot per bush by 18% and total shoot length by 24% compared with non-hydroponic culture. Total dry weight of a bush increased in the hydroponic with vigorous root growth 1.4-fold more than the non-hydroponic. Higher concentrations of inorganic elements and organic compounds were found in the hydroponic, indicating active nutrient absorption of the bush. The hydroponic produced high yield similar to adult bush from 4 years old age, maintaining the yield until 8 years old age. The findings of this study indicated that hydroponic cultivation systems will be useful for growing blueberry crop.

• Journal of the Korean Chemical Society
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• v.66 no.2
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• pp.124-135
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• 2022

The purpose of this study was to analyze the chemisry education contents of South Korea and North Korea for understanding chemistry education of North Korea. Chemistry education in South and North Korea was investigated in terms of learning period and learning quantaty. Especially, what content North Korea learned prior to South Korea and what contents learned more were analyzed. The subjects of this study were South Korean 2015 revised National Science Curriculum and North Korean science textbooks in Kim Jong-un era. The North Korean textbooks analyzed are 'Nature' for North Korean elementary school 3, 'Natural Science' for North Korean middle school 1 and 2, and 'Chemistry' for North Korean high school 1 and 2. The analysis results are as follows. First, the content elements to be learned in advance in North Korean textbooks were density, oxidation and reduction, battery, and atomic weight. Second, the content elements additionally learned in North Korean textbooks include separation of mixtures, fuels, oxidation and reduction, metals, organic and inorganic substances, metals and non-metal oxides and hydroxides, inorganic substances used as fertilizers, nutritional substances, and salt reaction and utilization, atomic orbitals, hybridization of orbitals, coordination bonds and complexes. As a future research task, a qualitative analysis of the elements of North Korean chemistry, the activities of textbooks, and an experimental analysis were proposed.

• Journal of the Korean Electrochemical Society
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• v.25 no.3
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• pp.105-112
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• 2022

For the commercialization of all-solid-state batteries, it is essential to develop a solid electrolyte that can be operable at room temperature, and it is necessary to manufacture all-solid-state batteries by adopting materials with high ionic conductivity. Therefore, in order to increase the ionic conductivity of the existing oxide-based solid, Li₇La₃Zr₂O₁₂ (LLZO) doped with heterogeneous elements was used as a filler material (Al and Nb-LLZO). An electrolyte with garnet-type inorganic filler doped was prepared. The binary metal element and the polymer mixture of poly(ethylene oxide)/poly(propylene carbonate) (PEO/PPC) (1:1) are uniformly manufactured at a ratio of 1:2.4, The electrochemical performance was tested at room temperature and 60 ℃ to verify room temperature operability of the all-solid-state battery. The prepared composite electrolyte shows improved ionic conductivity derived from co-doping of the binary elements, and the PPC helps to improve the ionic conductivity, thereby increasing the capacity of all-solid-state batteries at room temperature as well as 60 ℃. It was confirmed that the capacity retention rate was improved.

• Journal of Nutrition and Health
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• v.44 no.6
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• pp.474-480
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• 2011

Calcium (Ca) is an essential element to maintain body homeostasis. However, many factors disturb calcium absorption. Aspartic acid chelated calcium (AAC) was synthesized by new methods using calcium carbonate and aspartic acid. This study was carried out to investigate the bioavailability of AAC in Ca-deficient rats. The experimental groups were as follows: NC; normal diet control group, CD-C; untreated control group of Ca-deficient (CD) rats, CD-$CaCO_3$; $CaCO_3$ treated group of CD rats, CD-AAC; AAC treated group of CD rats, and CD-SWC; and seaweed-derived Ca treated group of CD rats. The Ca content of various types of Ca was held constant at 32 mg/day, and the four CD groups were fed for 7 days after randomized grouping. Ca content in serum, urine, and feces within feeding periods were analyzed to confirm Ca absorption. Serum Ca content was significantly higher in the CD-AAC (11.24 mg/dL) and CD-SWC (10.12 mg/dL) groups than that in the CD-C (8.6 mg/dL) group 2 hours following the first administration. The Ca content in feces was significantly lower in the CD-AAC (35.4 mg/3 days) and CD-SWC (71.1 mg/3 day) groups than that in the CD-$CaCO_3$ (98.7 mg/3 days) group (p > 0.05). AAC had a 2.3-fold higher absorption rate of Ca than that of SWC. No differences in fibula length were observed in the NC and CD groups. The fibula weights of the CD-AAC (0.33 g) and CD-SWC (0.33 g) groups increased compared to those in the CD-C (0.27 g) group; however, no significant difference was observed between the CD groups. We conclude that bioavailability of AAC is higher than that of seaweed-derived Ca or inorganic Ca. Thus, these findings suggest the AAC has potential as a functional food material related to Ca metabolism.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.1
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• pp.17-29
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• 2016

Though there is an abundant supply of nitrogen in the atmosphere, it cannot be used directly by the biological systems since it has to be combined with the element hydrogen before their incorporation. This process of nitrogen fixation ($N_2$-fixation) may be accomplished either chemically or biologically. Between the two elements, biological nitrogen fixation (BNF) is a microbiological process that converts atmospheric di-nitrogen ($N_2$) into plant-usable form. In this review, the genetics and mechanism of nitrogen fixation including genes responsible for it, their types and role in BNF are discussed in detail. Nitrogen fixation in the different agricultural systems using different methods is discussed to understand the actual rather than the potential $N_2$-fixation procedure. The mechanism by which the diazotrophic bacteria improve plant growth apart from nitrogen fixation such as inhibition of plant ethylene synthesis, improvement of nutrient uptake, stress tolerance enhancement, solubilization of inorganic phosphate and mineralization of organic phosphate is also discussed. Role of diazotrophic bacteria in the enhancement of nitrogen fixation is also dealt with suitable examples. This mini review attempts to address the importance of diazotrophic bacteria in nitrogen fixation and plant growth improvement.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.5
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• pp.523-533
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• 2011

This study had the aim of characteristics of $PM_{10}$ in subway cabins. $PM_{10}$ was measured by times of day (rush and non rush hours) and seasons with real time $PM_{10}$ sampler on the subway cabins of line 7. Filter samples were collected for evaluation of their elemental composition as well as identification of major sources of $PM_{10}$ using a receptor model, PMF. $PM_{10}$ concentration were the highest in the winter season both in the rush and non rush hours at 152.8 ${\mu}g/m^3$, 90.2 ${\mu}g/m^3$ respectively. The $PM_{10}$ concentrations in rush hour were 30% higher compared to non rush hours. Based on the chemical information, the composition rare of inorganic elements was 52.5%, anions were 10.2% and others were 37.3%. Fe was the most abundant element and significantly correlated (p.0.01) with Mn (r=0.97), Ti (r=0.91), Cr (r=0.88), Ni (r=0.89) and Cu (r=0.88). Characterized $PM_{10}$ sources by PMF in the cabin were soil and road dust related sources (27.2%), railroad related sources (47.5%), secondary nitrate sources (16.2%) and a Cl-factor mixed with a secondary sulfate source (9.1%).

• Journal of the Korean Wood Science and Technology
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• v.45 no.6
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• pp.753-761
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• 2017

The heartwood (HW) of Japanese cedar (Cryptomeria japonica) has usually a reddish color. But some trees have black-colored heartwood (BHW). BHW of Japanese cedar has a low commercial value because of the appearance. Therefore, in this study, a comparative analysis was conducted to evaluate the differences in the physical, mechanical, and inorganic element properties, and decay resistance of red-colored heartwood tree (RHW) and BHW. The physical properties showed significant difference between sapwood (SW) and HW, but there was no significant difference between RHW and BHW. From the results of mechanical properties, no significant difference was recognized in SW of RHW, HW of RHW, SW of BHW, and HW of BHW. There were decay resistance differences between RHW and BHW in HW, and between HW and SW in both RHW and BHW, respectively. The magnesium (Mg), potassium (K), and calcium (Ca) contents had significant differences between SW and HW in both RHW and BHW. In this present study, the decay resistances and the contents of Mg and K were higher in HW than in SW both for RHW and BHW, while these measurements were lower in RHW than in BHW. Therefore, BHW was considered to be worthy as a high-quality material as RHW.

• Korean Journal of Plant Resources
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• v.9 no.3
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• pp.254-260
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• 1996

The study was conducted to find out the ways of increasing fresh leaf yield under conditions of the optimum shading net treatment and planting densities of Aster glehni. Although the most effective shading net treatment to acclimatize the plant was 75% shading in 1993, as growing years were prolonged, effects of shading net treatment was not recognized. Ca contents in 75% shading net treatment was much higher than other shading net treatments. Shading effect tend to promote their growth and fresh leaf yield in 1993 even though 75% shading net treatment did not increase fresh leaf yield in 1994 and 1995. Planting density. $30\times20cm$. showed the effectiveness fresh leaf yield for 1994 and 1995 except for 1993.