• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.273-279
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• 2014

Hexagonal Ba-ferrites are widely suggested as materials for small antennas. In this paper, the sintering behavior and magneto-electric properties of $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ ($0.1{\leq}x{\leq}0.5$) ceramics were investigated for small antenna application. All samples of $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ ceramics were prepared by the solid-state reaction method and sintered at $1250^{\circ}C$. From the XRD patterns of the sintered $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ceramics, the Z-type phases were found to be the main phases. The real part of permittivity and permeability of the $Ba_3Co_{2-2x}Mn_{2x}Fe_{24}O_{41}$ceramics decreased with frequency. On the other hand, loss tangents of permittivity and permeability tended to behave opposite to real part of permittivity and permeability. The real part of permeability was affected by Mn additions. The real part of permittivity, the loss tangent of permittivity and the real part of permeability, the loss tangent of permeability of $Ba_3Co_{0.2}Mn_{0.8}Fe_{24}O_{41}$ ceramics were 19.774, 0.176 and 15.183, 0.073, respectively, at 510 MHz. In order to investigate the effect of magneto-dielectric ceramics on antenna, PIFA (Planar Inverted F Antenna) was simulated with CST (Computer Simulation Technology). The operating frequency of antenna was decreased without considerable change of bandwidth by using the $Ba_3Co_{0.2}Mn_{0.8}Fe_{24}O_{41}$ ceramics as the carrier.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.24.2-24.2
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• 2008

We have examined the relative contributions of representative space weather proxies (geomagnetic aa index) to global warming (Global temperature anomaly) and compared them with that of green house effect characterized CO2 content from 1868 to 2005. For this we used Hadcrut3 temperature anomaly (Ta) data, aa index taken at two anti-podal subauroral stations (Canberra Australia and hartland England), and the CO2 data come from historical ice core records. From the comparison between Ta and aa index, we found several interesting results: (1) the linear correlation coefficient between two parameters increases until 1990 and then decreases rapidly, and (2) the scattered plots between two parameters shows different patterns before and after 1990. A partial correlation of Ta and two quantities (aa, CO2) also shows that the geomagnetic effect (aa index) is dominant until about 1990 and the CO2 effect becomes much more important after then. These results imply that the green house effect become very important since at least 1990. For a further analysis, we simply assume that Ta (total) = Ta (aa) + Ta (CO2) and made a linear regression between Ta and aa index from 1868 to 1990. A linear model is then made from the linear regression between energy consumption (a proxy of CO2 effect) and Ta (total) - Ta (aa) since 1990. This linear model makes it possible to predict the temperature anomaly in 2030, about 1 degree higher than the present temperature, which is much larger than in the previous century.

• Journal of the Korean Magnetics Society
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• v.8 no.5
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• pp.282-287
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• 1998

Dependence of magnetoresistance on base pressure and deposition rates of each Fe, Co, Cu layers in the $Fe(50{\AA}/[Co(17{\AA})/Cu(24{\AA})]_20$ multilayer thin films, prepared by dc magnetron sputtering on Corning glass, were investigated. AFM analysis, X-ray diffraction analysis, vibrating sample magnetometer analysis, and magnetoresustance measurement (4-probe method) were performed. The multilayer films deposited under low base pressure increases magnetoresistance ratio by preventing oxidation. Annealing for the samples at a moderate temperature allowed larger textured grain with no loss in the periodicity. Magnetoresistance ratio of the annealed multilayers was increased due to the increase antiferromagnetically coupled fraction of the film after annealing. Optimization of deposition rate was greater than 1 $\AA$/s for Fe, and 2.8 $\AA$/s for Cu. Deposition rate of Co showed a tendency of increasing of magnetoresistance ratio due to the formation of flat magnetic layer in case of high deposition rate of Co.

• Journal of Embryo Transfer
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• v.10 no.2
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• pp.121-129
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• 1995

To examine the critical effect of oxygen concentration on embryonic development, in vitro fertilized embryos were cultured in media(TCM199 vs. SOF) supplemented sera(1O% FCS vs. 10% HS) with and without bovine oviduct epithelial cells under two gas atmosphere (5% $CO_2$ in air vs. 5% $CO_2$, 5% $O_2$, 90% $N_2$). Oocytes, obtained from abattoir ovaries, were matured in EGF containing TCM199 medium co-cultured with BOEC for 24 hours, followed by exposure to frozen-thawed, heparin4reated spermatozoa in TALP for 30 hours. And then early embryos(1~2 cell) were cultured in both TCM199 and SOF supplemented with 10% FCS or 10% RS under 5% $CO_2$ in air or 5% COi, 5% $O_2$, 90% $N_2$. Development to morulae and blastocysts was recorded on days 7, after the start of in vitro fertilization. The developmental rates of in vitro fertilized embryos to morulae and blastocysts cultured in SOF with BOEC under 5% $CO_2$, 5% $O_2$, 90% $N_2$(24.4%) were significantly(p<0.05) higher than cultured in SOF with BOEC under 5% $CO_2$ in air(14.1%) at seven days after in vitro fertilization. When early bovine embryos were cultured in TCM 199 and SOF under two different gas atmosphere, there were no significant differences in the developmental rates to morulae and blastocysts between supplements of 10% FCS and 10% HS. The rates of development to morulae and blastocysts were significantly(p<0.01) higher in TCM 199 with BOEC(24.7%) than TCM199 without BOEC(10.9%) under 5% $CO_2$ in air, otherwise SOF without BOEC(36.4%) were significantly (p<0.05) higher than in SOF with BOEC (24.4%) under 5% $CO_2$, 5% $O_2$, 90% $N_2$. In summary, these experiments have proved that the culture system in SOF supplemented 10% ES is effective on in vitro development of early bovine embryos under 5% $CO_2$, 5% $O_2$, 90% $N_2$. In addition, it is effective to development of bovine embryos that TCM 199 should be co-cultured with BOEC and SOF should be cultured without somatic cells under two different gas atmosphere.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.147-154
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• 2012

Recently, many researchers have studied the performance of the transcritical $CO_2$ refrigeration cycle in order to improve the system efficiency. In this study, the length of IHX in the $CO_2$ ejector cycle was varied so as to evaluate the performance improvement. As a result, compressor work and cooling capacity was increased by 3% and 5% as the length of internal heat exchanger was changed from 3 m to 15 m. The best COP was appeared at internal heat exchanger length of 12 m, and it was 3.01. Besides, the length of internal heat exchanger has a big effect to pressure lift ratio and entrainment ratio in the ejector $CO_2$ cycle and it may be changed with operating conditions and system specifications.

• Journal of the Korean Magnetics Society
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• v.19 no.1
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• pp.12-16
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• 2009

Z-type barium ferrite [($Ba_{3}Co_{0.8}Zn_{1.2}Fe_{24}O_{41}$, $Ba_{3+{\delta}}Co_{0.8}Zn_{1.2}Fe_{24}O_{41}$ ${\delta}$ = 3, 5, 7, 13 wt%. $Ba_{3}Co_{0.8}Zn_{1.2}Fe_{24+{\delta}}O_{41}$ ${\delta}$ = 5, 7, 10 wt% )] were synthesized using co-precipitation method. The microstructure and magnetic properties of synthesized particles were investigated. In all prepared particles M-type Ba ferrite is identified with Z-type Ba ferrite together. It is found that particles having 7 wt% for Ba and 5 wt% for Fe excess addition revealed high saturation magnetization, respectively. All synthesized particles showed relatively high coercivity for device application. This result may be attributed to the contribution of M-type Ba ferrite. Ba and Fe excess addition was not affected to the structural change of CoZnZ Ba ferrite. The certain amount of excess additions of Ba and Fe and the 2 step heat-treatment may be beneficial to the improvement of soft magnetic properties of Z-type barium hexa-ferrite

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.5
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• pp.567-575
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• 2018

Acute kidney injury (AKI), which is defined as a rapid decline of renal function, becomes common and recently recognized to be closely intertwined with chronic kidney diseases. Current treatment for AKI is largely supportive, and endoplasmic reticulum (ER) stress has emerged as a novel mediator of AKI. Since carbon monoxide attenuates ER stress, the objective of the present study aimed to determine the protective effect of carbon monoxide releasing molecule-2 (CORM2) on AKI associated with ER stress. Kidney injury was induced after LPS (15 mg/kg) treatment at 12 to 24 h in C57BL/6J mice. Pretreatment of CORM2 (30 mg/kg) effectively prevented LPS-induced oxidative stress and inflammation during AKI in mice. CORM2 treatment also effectively inhibited LPS-induced ER stress in AKI mice. In order to confirm effect of CO on the pathophysiological role of tubular epithelial cells in AKI, we used mProx24 cells. Pretreatment of CORM2 attenuated LPS-induced ER stress, oxidative stress, and inflammation in mProx24 cells. These data suggest that CO therapy may prevent ER stress-mediated AKI.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.2
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• pp.153-161
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• 2008

The guidelines for indoor air quality of public transportations such as subway, train and bus was presented by Korean Ministry of Environment last end of year 2006 based on the great consequence of indoor air quality in daily life. Two main parameters, carbon dioxide($CO_2$) and particulate matters smaller than $10\;{\mu}m(PM_{10})$, were selected as index pollutants for the management of indoor air quality. The former pollutant, $CO_2$, is regarded as index of ventilation status and the major source of $CO_2$ in the train or subway is the exhalation of passengers. It is publically perceived that the high $CO_2$ concentration in a crowded subway will be reduced and ventilated with outdoor air by door-opening taken every 2 or 3 minutes when the train stops each station. However, there has not been any scientific proof and quantitative information on the effect of door-opening on the $CO_2$ reduction by ventilation with outdoor air. In this study, $CO_2$ concentration and number of passengers were measured at each station on the 3 lines of Korail metropolitan subway. In order to evaluate the effect of $CO_2$ reduction by door opening, the theoretical approach using the $CO_2$ balance equation was performed. By comparing the predicted data with monitoring one, the optimum $CO_2$ dilution factor was determined. For the first time, it was quantified that about 35% of $CO_2$ concentration in the subway indoor was removed by the door-opening at each station.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.24-30
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• 1998

Inhibitory effects of the new material obtained from Areca catechu seed (CC-516) according to a special process, and its applicability to the skin as a cosmetic raw material in terms of its efficacy were presented. Areca catechu extract out of 150 medicinal plants, exhibited high inhibitory effect on the porcine pancreatic elastase ($IC_{50}$ : $40.8{\mu}$g/ml). It also had an inhibitory effect on the human leukocyte elastase ($IC_{50}$ : 48.1$\mu$g/ml), hyaluronidase ($IC_{50}$ : $416{\mu}$g/ml), antioxidative activity ($IC_{50}$ : $45.4\mu$g/ml) and free radical scavenging activity ($SC_{50}$ : $10.2{\mu}$g/ml). The cream contained 3％ of CC-516 improved skin hydration above 16.5％. Especially, the skin elasticity increases more than 35% and skin wrinkles decreased more than 23％. The CC-516 was designed to be utilized in cosmetology. The cream containing 3％ of this product has not only protecting effect on the skin mechanical properties provided by the collagen and the elastin in the derm but also restructuring effect of scarring or aging tissue.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.69-79
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• 2018

The Korean government attempts to reduce $CO_2$ emissions by 37% to 314.7 Mt $CO_2$, down from the estimated 850.6 Mt $CO_2$ until 2030 in order to confront green house effect. In this context, in 2014, Korean government launched $CO_2$ Storage Environmental Management Research (K-COSEM) Center for carrying out pilot-scale research on $CO_2$ leakage from underground $CO_2$ storage facilities. For the detection of $CO_2$ leakage, it is necessary to identify hydrologeological and geophysical characteristics of the subject area. In the study site of Naesan-ri, Daeso-myeon, Eumseong-gun, Chungbuk Province, two times injection tests (June 28-July 24, 2017 and August 07-September 11, 2017) of $CO_2$ and $SF_6$ dissolved waters, respectively, was conducted to understand the leakage behavior of $CO_2$ from underground. The injection well was drilled to a depth of 24 m with a 21-m casing and screen interval of 21~24 m depth. Two times resistivity surveys on August 18, 2017 and September 1, 2017, were conducted for revealing the flow of the injected water as well as the electrical properties of the study site. The study results have shown that the high-resistivity zone and the low-resistivity zone are clearly contrasted with each other and the flow direction of the injected water is similar to natural groundwater flow. Besides, the low resistivity zone is widely formed from the depth of injection to the shallow topsoil, indicating that the weathered zone of high permeability has high $CO_2$ leakage potential.