• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.363-363
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• 2014

Ruthenium (Ru) has attractive material properties due to its promising characteristics such as a low resistivity ($7.1{\mu}{\Omega}{\cdot}cm$ in the bulk), a high work function of 4.7 eV, and feasibility for the dry etch process. These properties make Ru films appropriate for various applications in the state-of-art semiconductor device technologies. Thus, it has been widely investigated as an electrode for capacitor in the dynamic random access memory (DRAM), a metal gate for metal-oxide semiconductor field effect transistor (MOSFET), and a seed layer for Cu metallization. Due to the continuous shrinkage of microelectronic devices, better deposition processes for Ru thin films are critically required with excellent step coverages in high aspect ratio (AR) structures. In these respects, atomic layer deposition (ALD) is a viable solution for preparing Ru thin films because it enables atomic-scale control of the film thickness with excellent conformality. A recent investigation reported that the nucleation of ALD-Ru film was enhanced considerably by using a zero-valent metallorganic precursor, compared to the utilization of precursors with higher metal valences. In this study, we will present our research results on the synthesis and characterization of novel ruthenium complexes. The ruthenium compounds were easy synthesized by the reaction of ruthenium halide with appropriate organic ligands in protic solvent, and characterized by NMR, elemental analysis and thermogravimetric analysis. The molecular structures of the complexes were studied by single crystal diffraction. ALD of Ru film was demonstrated using the new Ru metallorganic precursor and O2 as the Ru source and reactant, respectively, at the deposition temperatures of $300-350^{\circ}C$. Self-limited reaction behavior was observed as increasing Ru precursor and O2 pulse time, suggesting that newly developed Ru precursor is applicable for ALD process. Detailed discussions on the chemical and structural properties of Ru thin films as well as its growth behavior using new Ru precursor will be also presented.

• Journal of Animal Science and Technology
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• v.48 no.3
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• pp.393-400
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• 2006

The present study was conducted to evaluate feeding value of brown rice in Korean native beef steers (Hanwoo) fed concentrates and orchardgrass hay (50:50 on a wet basis) as a basal diet. Either 50% or 100% of corn in concentrates was substituted for brown rice, and ruminal fermentation characteristics, in situ degradability of feeds and in vivo digestibility of concentrate were investigated. The digestibility and nutritive values of corn and brown rice feeds were similar, whereas rumen degradability of brown rice was higher than that of corn. Compared with corn-based diets, the brown rice substitution decreased (P<0.05) ruminal NH3-N concentration, but did not affect rumen pH. Total volatile fatty acid content in ruminal digesta for the corn based diet was higher than those for the brown rice-contained diets. The brown rice substitution increased (P<0.05) the ratio of ruminal acetic acid to propionic acid (A/P) compared with corn-contained diets.Present results indicate that corn might nutritionally be substituted for brown rice as cattle feeds. In addition, we expect that relatively high A/P with brown rice may produce affirmative effects in rumen physiological aspect, particularly under the grain based feeding system for beef cattle in Korea.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.109-117
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• 2015

Aircraft needs an inlet duct to supply the airflow to engine face. A fighter aircraft that requires low radar observability has to hide the engine face in the fuselage to reduce the Radar Cross Section(RCS). Therefore, the flow path of the inlet duct is changed into S-shape. The performance of the aircraft engine is known to be influenced by the shape and the centerline curvature of the S-Duct. In this study, CFD analysis of the RAE M 2129 S-Duct has been performed to investigate the influence of aspect ratio of inlet geometry. The performance of the S-Duct is evaluated in terms of the distortion coefficient. To simulate the flow under adverse pressure gradient better, $k-{\omega}SST$ turbulence model is employed. The computational results are validated with the ARA experimental data. The secondary flow and the flow separation are observed for all computational cases, while the semi-circular geometry has been found to produce the best results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.7
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• pp.629-634
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• 2017

In the case of the UHP (Ultra high performance) tire that the demand has increased rapidly, compared with the commonly used tire, severe deformation has been observed because of the low aspect ratio. When repeated deformations are applied to the sidewall rubber, accumulated fatigue damage may cause fatigue failure. Thus, the evaluation of the durability of the tire sidewall rubber has become a very important issue to prevent accidents that occur while the vehicle is running. However, the research and design criteria for the durability performance of the tire sidewall rubber hardly exist. In this study, we suggest a lifetime prediction formula using strain energy density obtained by performing tensile tests and fatigue tests on two different kinds of the tire sidewall compounds. Additionally, the applicability of our findings for low fuel consumption tires was reviewed by converting the fatigue life of the sidewall rubber into the expected mileage of the tire.

• Korean Journal of Ecology and Environment
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• v.50 no.4
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• pp.422-431
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• 2017

The biogeochemical information of riverine organic matter gives a detailed and integrated recording of natural and anthropogenic activity within a watershed. To investigate the changes in quality and quantity of organic carbon transporting from mountain to ocean via river channels, we estimated the concentrations of dissolved (DOC) and particulate organic carbon (POC), and then traced the source origin of POC using stable carbon isotopes ratio before and after summer rainfalls in the Tamjin River and Ganjin Bay, Korea. Along the small watershed, a total of 13 sites including headwaters, dam reservoir, river and estuary were established for the study. We found some interesting findings in the aspect of distribution of DOC/POC concentration changing their origin sources dynamically flowing downstream. In particular, the river channel transport downstream mainly DOC to river mouth, although upper dam reservoir increased POC concentration by phytoplankton production in summer. Whereas, in the river mouth and estuary, POC was dominated not only by local supply from nearby reed saltmarsh, but also by marine phytoplankton production, respectively. The findings can contribute to increasing the understanding of riverine organic carbon transport in upper large dam and lower open estuary system.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.3
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• pp.390-400
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• 2010

This study is aimed to test physiological and hematological actions of Rheum palmatum through clinical pilot study optimized for usual oriental medicine prescription. Thirty-one cases were finally collected and the sample extract 100 $m{\ell}$ of Rheum palmatum (ERP) was administered two times in a day during 3 days and checked with blood CBC test, urinalysis, liver function test, abdominal X-ray as well as general diagnostic process of oriental medicine; pattern identification, assessment of shapes and constitution. The total toxic effective rate of ERP was 9.68% in 3 cases of the whole in case of consistent uneasy state in the subjective symptomatic assessment and aggravation of blood and urine examination. The relevant diagnostic factors were so-eum constitution and essence type subject, carapaces species, lung type in the aspect of Jisan shape theory. On the other hand, the positive effective rate of ERP was 29.03% manifesting improvement of vital signs or present illness and no abnormal changes of blood chemistry and urinalysis and simple abdomen radiology. The relevant diagnostic factors were tae-eum constitution, energy type subject, aves species, heart and liver type in Jisan's shape theory. And the other cases were manifesting no specific change through the administration of ERP. The ratio of the numbers of decrease and increase was 44:5 in the tenderness and hardness of abdominal palpation. But if the pattern identification doesn't comply with the aim of rhubarb application despite of constipation and abdominal pain, the tendeness and biochemical report was shown in abnormal change. The mean number of diarrhea by ERP was $16.77{\pm}6.95$ during 3 days after administration, and the frequent areas of abdominal pain were lower>middle>upper in order, and it meant the target site of ERP too. Besides, the toxic reaction against ERP was expressed highly in case of decrease in blood cell count and hemoglobin, hematocrit having blood deficiency syndrome. Likewise, the toxicity of ERP was influenced by pattern identification manifesting present disease condition and diagnostic factors of four constitutions, Jisan's shape theory collaterally. In conclusion, evaluation of herbal toxicity in order for using as a clinical guideline, various diagnostic pattern information and shape features like the above should be studied together with other pharmacologic toxicology test for the future.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.3
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• pp.293-299
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• 2014

Objectives: The main objective of this study is to investigate domestic usage amount of insecticide for vegetable cultivation to provide fundamental data for establishing job-exposure matrix(JEM) related to farmers treating agricultural insecticide. Materials and Methods: The survey on domestic usage amount of insecticide for vegetable cultivation was conducted by two research methods. The first method is to utilize agricultural pesticides published annually from Korea Crop Protection Association(KCPA). The second method is to apply cultivation area of vegetable announced officially from Statistics Korea(SK). An estimation of domestic usage amount of insecticide for vegetable cultivation through the second method was done by multiplying total cultivation area of vegetable($m^2$) with optimal spray amount of insecticide for vegetable cultivation per unit cultivation area of vegetable ($kg/m^2$). Results: As a result of analysis of public data related to insecticide for vegetable cultivation, it was found that its domestic usage amount has decreased gradually from the first sale year(1969) to current year(2012). There is, however, a considerable difference of annual usage trend of insecticide for vegetable cultivation between shipments and estimation. The annual usage trends of insecticide for vegetable cultivation based on regional classification were different from those based on total aspect. Conclusions: The region which used insecticide for vegetable cultivation the most in Korea was Jeolla-do, followed by Gyeonsang-do, Chungcheong-do, Seoul/Gyeonggi-do, Gangwon-do and Jeju-do. Substantially, mean ratio of usage amounts of insecticide based on shipments and those based on estimation by cultivation area was $281{\pm}115%$, which indicates that usage amounts of insecticide estimated by cultivation area are three times lower than those based on shipments.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.1
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• pp.59-64
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• 2014

Objectives: The principal aim of this study is to investigate and analyze domestic usage amounts of insecticide in rice cultivation in order to provide fundamental data for establishing a job-exposure matrix(JEM) related to farmers working with agricultural insecticides. Materials and Methods: An investigation of domestic usage amounts of insecticides rice cultivation was performed through two methods. The first method utilized information on agricultural pesticides published annually by the Korea Crop Protection Association(KCPA). The second method made use of area of cultivation of rice as officially determined by Statistics Korea(SK). An estimation of domestic usage of insecticides in rice cultivation through the second method was determined by multiplying the total cultivation area of rice($m^2$) by the optimal spray volume of insecticides for rice cultivation per unit of cultivation area($kg/m^2$). Results: As a result of the analysis of public data regarding insecticides in rice cultivation, it was found that the domestic usage amount has decreased sharply from the first year of market sales(1969) to the final data year(2012). There is little difference in the annual usage trend of insecticides in rice cultivation between shipment and estimation. Also, the annual usage trends of insecticides in rice cultivation based on regional classification were nearly similar to those based on the overall aspect. Conclusions: The region which used the largest volume of insecticide in rice cultivation in Korea was the Jeolla Provinces, followed by the Gyeonsang Provinces, the Chungcheong Provinces, Seoul/Gyeonggi Province, Gangwon Province and Jeju Province. Substantially, the mean ratio of usage amounts of insecticide based on shipments and those based on estimation by cultivation area was $96{\pm}29%$, which indicates that the domestic usage amount of insecticide for rice cultivation corresponded to the optimal spray standard per unit area.

• Membrane Journal
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• v.27 no.2
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• pp.154-166
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• 2017

Polymeric films for gas barrier applications such as food packaging and electronic devices have attracted great interest due to their cheap, light and easy processability among gas barrier materials. Especially in electronic devices, extremely low gas permeance is necessary for maintaining the device performance. However, current polymeric barrier films still suffer from relatively high gas permeance than other materials. Therefore, there have been strong needs to enhance the gas barrier performance of polymeric barrier films while keep their own advantages. Recently, graphene is highlighted as a 2D-layered material for gas barrier applications. However, owing to the poor workability and difficulty to produce in engineering scale, graphene oxide (GO) is on the rise. GO consists of oxygen-containing functional groups on surface with intrinsic 2D-layered structure and high aspect ratio, and it can be well-dispersed in aqueous polar solvents like water, resulting in scalable mass production. Here, we prepared GO incorporated polyimide (PI) nanocomposites. PI is widely used barrier polymer with high mechanical strength and thermal and chemical stability. We demonstrated that PI/GO nanocomposites could perform as a gas barrier. Furthermore, surfactants (Triton X-100 (TX) and Sodium deoxycholate (SDC)) are introduced to enhance the gas barrier performance by improving the degree of dispersion of GO in PI matrix. As a result, TX enhanced the gas barrier performance of PI/GO nanocomposites which is similar to predicted value. This finding will provide new insight to polymer nanocomposites for gas barrier applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2415-2423
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• 2015

Experiments were conducted on sine wave fin-and-tube heat exchangers having oval tubes under wet condition. Oval tubes having an aspect ratio of 0.6 were made, by deforming 12.7mm round tubes. Twelve samples, having different fin pitch and tube row, were tested. Results showed that, for oval tube samples, the effect of fin pitch on j and f factor was not significant. As for the effect of tube row, the lowest j factor was obtained for one row configuration(81% of two row configuration), which is clear contrast to round tube samples, where the highest j factor was obtained for one row configuration. Possible reasoning is provided considering the flow and heat transfer characteristics of sine wave channel combined with connecting oval tubes. Comparison of $j/f^{1/3}$ with plain fin-and-tube heat exchanger having 15.9mm O.D. round tube reveals that present oval fin-and-tube heat exchanger shows superior thermal performance except for one row configuration. In other words, $j/f^{1/3}$ of the two row oval tube heat exchanger was 1.6~2.5 times larger than those of round tube heat exchanger, 1.4~2.4 times larger for three row configuration and 1.2~2.8 times for four row configuration.