• Journal of Korea Foundry Society
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• v.34 no.6
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• pp.200-213
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• 2014

Pure magnesium and magnesium alloys have been applied to various kinds of industrial fields, especially automotive and electronic parts. These parts are manufactured mainly through a diecasting process. These days, magnesium ingots are used as raw material, and recycled ingots are often used for commercial purposes. But the quality of virgin magnesium and recycled ingots is not secure. Therefore, massive casting defects can occur, and some things manufactured can be damaged by these defects. This study evaluated the inclusions of virgin magnesium and recycled ingot. It also included composition analysis by spectrometer, measuring inclusion contents by SEM & EDS, and performing a brightness test on fractured surfaces. The brightness test is generally very easy and obtains results quickly, so its results have been compared with the results obtained from various test methods. From the test results, we obtained a satisfactory result in evaluating inclusion and oxide. The brightness values are lower as the inclusion contents are higher. When the brightness value is over 47 in AM50A and 44 in AZ91D, the mechanical properties are expected to be good.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2498-2503
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• 2023

When the reactor vessel is penetrated in a severe accident of light water reactor, the molten fuel-coolant interaction including the jet breakup occurs and the jet breakup length becomes one of the important parameters. Most numerical studies on jet breakup process have been carried out using dedicated computer codes. Some researchers are trying to apply commercial CFD codes to their investigations on comprehensive jet breakup process. However, the complexity of the phenomena limits the CFD application only to hydrodynamic aspects. In the present study, numerical analysis of jet breakup under vapor generation is pursued using the STAR-CCM + code. The obtained CFD prediction of the MATE09 experiment shows jet breakup progression patterns consistent to the images taken in the experiment. Further, the predicted positions of leading head, which determine the jet breakup length, are in good agreement with the MATE 09 data. The investigation of hydrodynamic effects on the jet breakup with higher jet velocity results in a stronger shear force and earlier jet breakup process even though there exists the vapor pocket around the corium jet. In future studies, the effect of vapor intensity on the jet breakup length would be investigated further by changing other parameters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.2
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• pp.100-105
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• 2006

This study was conducted to evaluate the effects of extruded pellet (EP) diets, as compared to a raw fish moist pellet (MP) diet for olive flounder, Paralichthys olivaceus, grown in commercial-scale aquaculture for 1 year. Four diets with duplication per diet were formulated for this experiment: two experimental EP diets (EP1 and EP2), one commercial EP diet (CEP), and a raw fish MP diet (MP). The MP diet consisted of 80% frozen horse mackerel and 20% commercial binder meal. Fish weighing $30.1{\pm}0.1 g$ ($mean{\pm}SD$) were distributed randomly to each aquarium as a group of 2,600 fish. Weight gain (WG) and feed efficiency ratio (FER) of fish fed EP2 and MP were higher (P<0.05) than those of fish fed CEP, while those of fish fed EP1 did not differ (P>0.05) from those fed EP2 and MP. However, fish fed the MP diet had a higher survival rate than fish fed the other diets. Fish fed EP2 had higher serum, phospholipids and total protein levels, and lower levels of serum glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), and total cholesterol than fish fed MP (P<0.05). Dorsal muscle and liver proteins and lipid of fish fed EP1 were higher (P<0.05) than those of fish fed CEP, while those of fish fed EP1 and MP did not differ from those of fish fed EP2 (P>0.05). These results strongly suggest that EP1 could be developed to replace MP for grow-out stage production of olive flounder without adverse effects on growth performance.

• Journal of the Korean Ceramic Society
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• v.42 no.12 s.283
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• pp.842-845
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• 2005

Glass composites containing ceramic fiber have been developed for Solid Oxide Fuel Cell (SOFC) seals. Effect of glass type, loading pressure and thermal cycle the leak rates of composite seals was investigated. Seal performance of two commercial glasses was compared with that of $SiO_2BaO-B_2O_3$ glass synthesized in this work. The leak rate for seals made of pyrex(R) increases from $\~0.0005\;to\;\~0.004sccm/cm$ as the gas pressure increases from 10 to 50 kPa. The soda lime silicate glass seal shows the leak rate two times higher than the one made of pyrex(R) or $SiO_2BaO-B_2O_3$ glass. The viscosity of glass at the seal test temperature is presumed to affect the leak rate of the glass seal. As the applied loading pressure increases from 0.4 to 0.8 MPa at $750^{\circ}C$, the leak rate decreases from 0.038 to 0.024 sccm/cm for composite seals. It has been found that during 50 thermal cycles between $450^{\circ}C\;to\;700^{\circ}C$ leak rates remained almost constant, ranging from 0.025 to 0.03sccm/cm. The results showed an excellent thermal cycle stability as well as sealability of the glass matrix ceramic fiber composite seals.

• Food Science of Animal Resources
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• v.33 no.1
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• pp.83-88
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• 2013

This study investigated the effect of wild grape (Vitis coignetiae) dietary supplementation on the antioxidative potential and quality of the breast and leg meat of broilers. A total of 36 one-day-old male Cobb broiler chicks were obtained from a commercial hatchery, and randomly assigned to 9 pens with 4 birds per pen. Then, broilers were fed 3 different dietary supplementations, including 0%, 0.25%, or 0.5% wild grape, for 2 wks at the finishing period. After slaughtering, the total phenolic content, ${\alpha}$,${\alpha}$'-diphenyl-${\beta}$-picryl-hydrazyl (DPPH) radical scavenging activity, 2-thiobarbituric acid reactive substances (TBARS), and total cholesterol content of broiler breast and leg meat were measured. Higher total phenolic content was recorded in the leg meat of broilers fed the wild grape when compared with the control, while breast meat did not show any difference. Dietary supplementation of 0.25% and 0.5% wild grape significantly increased DPPH radical scavenging activity of both breast and leg meat. TBARS values of both breast and leg meat were decreased by supplementation of 0.5% wild grape during storage when compared to the control, except for the leg meat at day 7. However, there was no significant difference found in total cholesterol content in both breast and leg meat. The results indicate that the antioxidative potential of broiler meat is improved by supplementing the diet with wild grape.

• The Plant Pathology Journal
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• v.33 no.5
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• pp.467-477
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• 2017

A nationwide survey was performed to investigate the current incidence of viral diseases in Korean sweet potatoes for germplasm and growing fields from 2011 to 2014. A total of 83.8% of the germplasm in Korea was infected with viruses in 2011. Commercial cultivars that were used to supply growing fields were infected at a rate of 62.1% in 2012. Among surveyed viruses, the incidence of five Potyvirus species that infect sweet potato decreased between 2012 and 2013, and then increased again in 2014. Representatively, the incidence of Sweet potato feathery mottle virus (SPFMV) was 87.0% in 2012, 20.7% in 2013 and then increased to 35.3% in 2014. Unlike RNA viruses, DNA viruses were shown to decrease continuously. The incidence of Sweet potato leaf curl virus (SPLCV) was 5.5% in 2003, 59.5% in 2011, and 47.4% in 2012. It then decreased continuously year by year to 33.2% in 2013, and then 25.6% in 2014. While the infection rate of each virus species showed a tendency to decline, the virus infection status was more variable in 2013 and 2014. Nevertheless, the high rate of single infections and mixed infection combinations were more variable than the survey results from 2012. As shown in the results from 2013, the most prevalent virus infection was a single infection at 27.6%, with the highest rate of infection belonging to sweet potato symptomless virus-1 (SPSMV-1) (12.9%). Compared to 2013, infection combinations were more varied in 2014, with a total of 122 kinds of mixed infection.

• The Korean Journal of Pesticide Science
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• v.20 no.1
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• pp.35-40
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• 2016

Recently, bacterial angular leaf spot disease, caused by Xanthomonas fragariae, causes severe damage in strawberry production and its' export to other countries, since the pathogen has been classified as an A2 quarantine pathogen. Typical the Angular Leaf Spot (ALS) disease represent that water-soaked angular spots symptoms, bacteria ooze exudate under relatively high humidity condition and later the spot become reddish brown on the leaf surface. The pathogen disseminated by irrigation water, infected mother plant and farmer's hand. In this study, we reported that rubbing inoculation method showed more effective in the pathogen dissemination than infiltration with needles, regardless the strawberry cultivars. Additionally, Dichloroisocyanurate (NaDCC) treatment in commercial strawberry fields provided reliable efficiency to reduce the bacterial angular leaf spot disease incidency and severity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.537-544
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• 2014

Kwamaegi is a traditional Korean seafood made from the flesh of Pacific saury Cololabis saira. It is recognized as a valuable, healthy food containing the ${\omega}$-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). This study was conducted in order to obtain basic data for application to the canning process of Kwamaegi using red pepper paste with vinegar. Commercial Kwamaegi was cut into $2{\times}3cm$ lengths and 90 g was put into cans (301-3). Then, 60 g of water was added and precooked for 10 minutes at $100^{\circ}C$. The water was drained after precooking. The precooked Kwamaegi was packed into cans, and 60 g of red pepper paste with vinegar was added. The cans were seamed using a vacuum seamer, then sterilized for differing times (8-12 minutes) in a steam system retort at $121^{\circ}C$. Parameters such as: pH, TVB-N, amino-N, total amino acid content, free amino acid content, color value (L, a, b), texture profile, TBA value, mineral content, sensory evaluation and viable bacterial count of the product produced under varying sterilization times (8-12 minutes) were measured. There were no remarkable differences between sterilization conditions and textural characteristics. The results showed that product sterilized for 8 minutes proved to be the most desirable.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.87-103
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• 2008

In recent years, the field of THz photonics based on THz pulse technology has gained tremendous, world-wide interest as a new exciting research subject. With a possibility of many commercial applications as well as fundamental scientific achievements in the field, many advanced nations are stepping up their effort in advancing the field of THz photonics. This fact is supported by the observation of the significant increase in the number of papers on THz pulse technology presented in renowned international journals and conferences. The subject that is interesting for the THz application is the development of THz pulse sources and detectors, and other passive devices. In this paper, we present a brief review on some of the key devices and their relavant measurement techniques such as THz photoconductive antennas, optical rectification, difference frequency geneneration with quasi-phase matching structures, electro-optic sampling, high speed real time measurements, THz transmission lines, and other various waveguide structures.