• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.5
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• pp.601-608
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• 2019

In this study, the effect of hull appendages on the high-speed catamarans with reverse bow shapes is compared and analyzed by numerical analysis and circulating water tank model test. The reverse bow shape showed an improved wave shape by shifting the generation position of forward divergent wave to the stern direction and was effective in resistance and stable running posture (Kim et al., 2019). In the model test results of the running performance as the wave patterns and the change of the running posture due to the fin fitted with the inner side of the inverted bow and the interceptor, 1) Trim characteristics of the inverted bow 2) Improvement of superposition of inner wave by Fin 3) The trim control by the fin and the interceptor is considered to be effective in reducing the impact of the two hull connection decks (wetdeck).

• Journal of the Korea Institute of Building Construction
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• v.19 no.4
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• pp.299-306
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• 2019

In general, repair mortar is used to rehabilitate underground communities, but difficulties are encountered in the execution of long-term construction due to spatial co-operatives. In this study, the engineering properties of repair mortar according to the curing condition and accelerator type were reviewed. The results showed that the aluminate, alkali-free and calcium-aluminate precipitates in the water curing conditions showed higher compressive strength at the beginning of age than mortar specimens under air curing conditions, and increased. Especially in CA and AF test specimen with cement mineral quick setting, a large amount of ettringite products were observed compared with AL, thus reducing the pore volume and increasing the strength of the compound by micro-filling effect were found.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.44-49
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• 2019

The purpose of this study is to analyze the fundamental characteristics of concrete with the change of reject ash(Reject ash=Rj) in the mixed aggregate where single grain aggregate of different grain size and aggregate of opposite grain size are mixed together, to analyze the possibility of a mixed aggregate system that premixes at an aggregate manufacturing plant and delivers it as one aggregate. As a result of the experimental study, it was found that the grain size regulation is satisfied if the mixed aggregate(CSb+SS) is substituted for about 5% of Rj. In the case of the fluidity slump, slump flow and air volume, it was found that they decrease as the substitution ratio of Rj increases, while the compressive strength increases as the substitution ratio of Rj increases. Therefore, it is analyzed that it would contribute greatly to an improvement of quality such as improvement of compressive strength if adequate fluidity and air quantity are secured by the water reducing agent and AE agent while premixing the Rj, which is disposed of by landfill, with about 5% of the mixed aggregate.

• The Korean Journal of Food And Nutrition
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• v.31 no.6
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• pp.883-889
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• 2018

This study was carried out to investigate the quality characteristics of yanggaeng added with jujube extracts. The jujube extracts were incorporated into yanggaeng at different levels (containing 25%, 50%, 75%, and 100% jujube extracts) based on the total weight of water. To analyze the quality characteristics in the manufacture of yanggaengs, pH, moisture content, density of dough, height, specific volume, baking loss, texture, color, antioxidant activity, total polyphenol content, and sensory test were determined. As the content of jujube powder increased, the pH of yanggaengs decreased but the acidity increased. There was no significant difference in the moisture content depending on the addition of jujube extracts. The color, lightness and redness of yanggaengs decreased as the concentration of the extract increased, whereas the yellowish color increased. As the jujube extracts content increased, total polyphenol content, antioxidant activity, reducing sugar and total tannins significantly increased. The yanggaeng contains jujube extract with acceptable sensory properties, such as color, sweet taste, and overall acceptability, which could be integrated into yanggaengs to meet the taste and functional needs of the consumers.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.91-97
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• 2019

Application of bioretention systems in Korea is highly considered due to its minimal space requirements, appropriateness as small landscape areas and good pollutant removal and peak hydraulic flow reduction efficiency. In this study, the efficiency of two lab-scale bioretention types having different physical properties, media configuration and planted with different shrubs and perennials was investigated in reducing heavy metal pollutants in stormwater runoff. Type A bioretention systems were planted with shrubs whereas type B were planted with perennials. Chrysanthemum zawadskii var. latilobum (A-CL) and Aquilegia flabellata var. pumila (A-AP) respectively were planted in each type A bioretention reactors while Rhododendron indicum linnaeus (B-RL) and Spiraea japonica (B-SJ), respectively were planted in each type B bioretention reactors. Results revealed that the four lab-scale bioretention reactors significantly reduced the influent total suspended load by about 89 to 94% (p<0.01). Type B-RL and B-SJ reactors reduced soluble Cr, Cu, Zn, and Pb by 28 to 45% that were 15 to 35% greater than the soluble metal reduction of type A-CL and A-AP reactors, respectively. Among the pollutants, total Cr attained the greatest discharged fraction of 0.52-0.81. Excluding the effect of soil media, total Pb attained the greatest retention fraction in the bioretention systems amounting to 0.15-0.34. Considering the least discharge fraction of heavy metal in the bioretention system, it was observed that the bioretention systems achieved effectual reduction in terms of total Cu, Zn and Pb. These findings were associated with the poor adsorption capacity of the soil used in each bioretention system. The results of this study may be used for estimating the maintenance requirements of bioretention systems.

• Journal of the Korea Institute of Building Construction
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• v.19 no.2
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• pp.139-147
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• 2019

In this study, an experiment was conducted to evaluate the properties of cement matrix using diatomite and silica gel as adsorbents of radon. The adsorption properties of diatomite of a natural adsorbent and silica gel of an artificial sorbent were examined to confirm the reduction of radon gas concentration of the removal of radon gas in the indoor environment of the human body. We conducted a performance evaluation for the study. The fluidity, air content, density, absorption, flexural failure load, thermal conductivity and radon gas concentration of the specimen using diatomite and silica gel were measured. the fluidity and the air content of the adsorbed matrix with diatomite were decreased as the diatomite replacement ratio increased. Which seems to affect the subsequent matrix by the absorption of the compounding water of diatomite. As the replacement rate of silica gel increased, the fluidity decreased and the air content increased up to constant replacement rate. It is judged that the surface of the silica gel has a critical point at which it can react with moisture.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.8
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• pp.51-58
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• 2018

G-SEED has been introduced with the aim of reducing energy use and resources since 2002, as the system of certificating environmental friendliness of buildings to create comfortable environment. This study analyzed the changes of certification standard of G-SEED since the revision in 2016, comparing certification results of office buildings by grade, category and certification items between G-SEED 2013-2 version and revised version of 2016. Also, this study analyzed the average points and their standard deviation of certification items including both deleted items and newly added items and extracted items needed to be reviewed in the future revision. In the revision, G-SEED has been extended its certification system to involve existing buildings and Innovative Design categories newly introduced with revising the certification items and difficulties. In revised version of G-SEED, the certification grade appeared to change its acquisition ratio decreasing Green2 and increasing Green4, during Green1 and Green3 were similar in proportion. The average scores by categories appeared decrease in Energy and Environmental Pollution category and Materials and Resources category, on the other hand, Maintenance category appeared the highest increase in the average score. Otherwise, Land Use and Transportation, Water Circulation, Ecology, Indoor Environment categories appeared similar average scores both version of G-SEED. In addition, the Innovative Design which was newly introduced category, seems to expect gradual gaining high scores according to technology development in future, although its possession has shown lower scores in revised version.

• Journal of Microbiology and Biotechnology
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• v.31 no.6
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• pp.815-822
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• 2021

Indigenous fungus-feeding nematodes may adversely affect the growth and activity of introduced biocontrol fungi. Alginate pellets of the biocontrol fungus Trichoderma harzianum ThzID1-M3 and sclerotia of the fungal plant pathogen Sclerotinia sclerotiorum were added to nonsterile soil at a soil water potential of -50 or -1,000 kPa. The biomass of ThzID1-M3, nematode populations, and extent of colonization of sclerotia by ThzID1-M3 were monitored over time. The presence of ThzID1-M3 increased the nematode population under both moisture regimes (p < 0.05), and fungivores comprised 69-75% of the nematode population. By day 5, the biomass of ThzID1-M3b and its colonization of sclerotia increased and were strongly correlated (R² = 0.98), followed by a rapid reduction, under both regimes. At -50 kPa (the wetter of the two environments), fungal biomass and colonization by ThzID1-M3 were less, in the period from 5 to 20 days, while fungivores were more abundant. These results indicate that ThzID1-M3 stimulated the population growth of fungivorous nematodes, which in turn, reduced the biocontrol ability of the fungus to mycoparasitize sclerotia. However, colonization incidence reached 100% by day 5 and remained so for the experimental period under both regimes, although hyphal fragments disappeared by day 20. Our results suggest that indigenous fungivores are an important constraint for the biocontrol activity of introduced fungi, and sclerotia can provide spatial refuge for biocontrol fungi from the feeding activity of fungivorous nematodes.

• Journal of radiological science and technology
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• v.44 no.3
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• pp.261-267
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• 2021

As the number of Coronavirus Disease-19 (COVID-19) patients increases in a global pandemic situation, the usefulness of mobile computed tomography (CT) is gaining attention. Currently, mobile CT follows the basic safety and essential performance evaluation criteria of whole-body or limited-view X-ray CT in order to obtain device approval and evaluation in the Republic of Korea. Unlike stationary CT, mobile CT is not operated in shielded areas but rather areas such as intensive care units, operating rooms, or isolation rooms. Therefore, it requires a different basic safety and essential performance evaluation standard than stationary CT. In this study, four derived basic safety evaluation criteria related to electrical, mechanical, and radiation safety were included (dose indication test, protection against stray radiation, safety measures against excessive X-rays, half-value layer measurement); and seven essential performance evaluation criteria were included (tube voltage accuracy, mAs accuracy, radiation dose reproducibility, CT number of water, noise, uniformity, and spatial resolution); total eleven basic safety and essential performance evaluation criteria were selected. This study aims to establish appropriate basic safety and essential performance evaluation criteria for simultaneously obtaining images with diagnostic value and reducing the exposure of nearby patients, medical staff, and radiologic technologists during the use of mobile CT.

• Journal of the Korea Safety Management & Science
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• v.22 no.4
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• pp.9-15
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• 2020

As of 2018, total yield of lettuce and strawberry amounted to 93,543 tons (representing 1.0 percent) and 183,639 tons (2.0 percent), respectively, among total yields worth 9,185,889 tons in South Korea. Lettuce is affected by a combination of numerous elements such as varieties, cultivation methods and pests during each growth phase (Lee et al., 1999). It is mainly cultivated in spring and fall. Especially due to respiration rate after harvest leading to reduced quality and poor storage, maintaining annual supply is unavailable (Jang et al., 2018). With the distribution of new varieties, forcing culture and indoor insulated facilities for plant cultivation during winter, strawberries are produced every year except for late summer and early fall. Due to active respiration, transpiration, soft flesh and high water content, the fruit is vulnerable to go bad and got rotten compared to other fruits. Furthermore, it is difficult to maintain freshness due to the possibility of softening, discoloration and fungi (Lee et al., 2012). In this regard, developing improved storage and package techniques is needed to ensure maintaining quality and safety even just two to three days after harvest. In order to ensure improved quality and safety of strawberries and lettuce after harvest, the present study applied a modified atmosphere packaging (MAP) technology (Mostofi et. al., 2008). Going forward, it compared the quality and safety of the two products while being stored in a way that put them in an MAP-applied container and a plastic container at room temperature and 4 degree Celsius.