• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.5
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• pp.208-214
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• 2019

The glass of $BaO-GeO_2-La_2O_3-ZnO$ system with a transmittance of more than 75 % at mid-wave infrared (MWIR) region in the range of $3{\mu}m$ to $5{\mu}m$ is manufactured and its property is evaluated. After selecting construction that can melt glass through flow button test, $BaO-GeO_2-La_2O_3$ system where 10 mol%, 20 mol% of ZnO were added respectively were melted at $1350^{\circ}C$ for 1 hour and $BaO-GeO_2-La_2O_3$ system of glass was manufactured. Among them, with 20 mol% of ZnO, 16 mol% BaO-56 mol% $GeO_2-8mol%$ $La_2O_3-16mol%$ ZnO system of glass was found to has less than $660^{\circ}C$ of glass transition temperature, more than 1.70 of refractive index, and more than 530 of knoop hardness. Therefore, it is concluded that glass of $BaO-GeO_2-La_2O_3-ZnO$ system of glass with 20 mol% ZnO has good melting conditions at low temperatures and excellent optical properties, thus, can be utilized for special optical materials field.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.105-115
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• 2021

The geological CO2 sequestration in underground geological formation such as deep saline aquifers and depleted hydrocarbon reservoirs is one of the most promising options for reducing the atmospheric CO2 emissions. The process in geological CO2 sequestration involves injection of supercritical CO2 (scCO2) into porous media saturated with pore water and initiates CO2 flooding with immiscible displacement. The CO2 migration and distribution, and, consequently, the displacement efficiency is governed by the interaction of fluids. Especially, the viscous force and capillary force are controlled by geological formation conditions and injection conditions. This study aimed to estimate the effects of surfactant on interfacial tension between the immiscible fluids, scCO2 and porewater, under high pressure and high temperature conditions by using a pair of proxy fluids under standard conditions through pendant drop method. It also aimed to observe migration and distribution patterns of the immiscible fluids and estimate the effects of surfactant concentrations on the displacement efficiency of scCO2. Micromodel experiments were conducted by applying n-hexane and deionized water as proxy fluids for scCO2 and porewater. In order to quantitatively analyze the immiscible displacement phenomena by n-hexane injection in pore network, the images of migration and distribution pattern of the two fluids are acquired through a imaging system. The experimental results revealed that the addition of surfactants sharply reduces the interfacial tension between hexane and deionized water at low concentrations and approaches a constant value as the concentration increases. Also it was found that, by directly affecting the flow path of the flooding fluid at the pore scale in the porous medium, the surfactant showed the identical effect on the displacement efficiency of n-hexane at equilibrium state. The experimental observation results could provide important fundamental information on immiscible displacement of fluids in porous media and suggest the potential to improve the displacement efficiency of scCO2 by using surfactants.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.701-711
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• 2020

Purpose: In this study, the risk of flammability of a liquid mixture was experimentally confirmed because the purpose of this study was to confirm the increase or decrease of the flammability risk in a mixture of two substances (combustible+combustible) and to present the risk of the mixture. Method: Flash point test method and result processing were tested based on KS M 2010-2008, a tag sealing test method used as a flash point test method for crude oil and petroleum products. The manufacturer of the equipment used in this experiment was Japan's TANAKA. The flash point was measured with a test equipment that satisfies the test standards of KS M 2010 with equipment produced by the company, and LP gas was used as the ignition source and water as the cooling water. In addition, when measuring the flash point, the temperature of the cooling water was tested using cooling water of about 2℃. Results: First of all, in the case of flammable + combustible mixtures, there was little change in flash point if the flash point difference between the two substances was not large, and if the flash point difference between the two substances was low, the flash point tended to increase as the number of substances with high flash point increased. However, in the case of toluene and methanol, the flash point of the mixture was lower than that of the material with a lower flash point. Also, in the case of a paint thinner, it was not easy to predict the flash point of the material because it was composed of a mixture, but as a result of experimental measurement, it was measured between -24℃ and 7℃. Conclusion: The results of this study are to determine the risk of mixtures through experimental studies on flammable mixtures for the purpose of securing the effectiveness of the details of the criteria for determining dangerous goods in the existing dangerous goods safety management method and securing the reliability and reproducibility of the determination of dangerous goods Criteria have been presented, and reference data on experimental criteria for flammable liquids that are regulated in firefighting sites can be provided. In addition, if this study accumulates know-how on differences in test methods, it is expected that it can be used as a basis for research on risk assessment of dangerous goods and as a basis for research on dangerous goods determination.

• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.586-593
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• 2020

This study was conducted to investigate the biological characteristics of Phanuromyia ricaniae (Hemiptera: Platygastroidea), an egg parasitoid of Ricania sp. (Hemiptera: Ricaniidae) as a biological control agent to control Ricania sublimata. The developmental period of P. ricaniae was 3.8 days for eggs, 11.1 days for larvae, and 16.3 days for pupae at 25℃, and 3.4 days for eggs, 7.8 days for larvae, and 15.3 days for pupae at 30℃. Except for the larval stage, the developmental periods were not significantly different, but the egg-to-pupa period at 30℃ was significantly shorter than that at 25℃. P. ricaniae emerged at the photophase in 24 hours, but not at the scotophase. A higher emergence rate (34.5%) was seen from 10:00 to 12:00 after the lights were turned. The female-to-male ratio of P. ricaniae was 3:1. The longevity of P. ricaniae adults was 49.0 days for females and 44.0 days for males at 20℃, 27.6 days for females and 28.4 days for males at 25℃, and 18 days for females and 14.0 days for males at 30℃. Its longevity at a low temperature (20℃) was longer than that at higher temperatures (25 and 30℃). Adult females laid eggs during all days except from 00:00-02:00 (scotophase time). The ovipositional distribution rate was 26.1% from 20:00 to 22:00, which was the peak, and the next peak was 15.7% at 10:00 to 12:00. P. ricaniae showed arrhenotokous parthenogenesis in which unfertilized eggs develop into males. Therefore, the results suggest that P. ricaniae may be a biological control agent for R. sublimata.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.170-187
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• 2020

Dolmens bearing the burial layout and stone coffin tombs of the late Bronze Age were excavated from Samdeok-ri, Goseong, Gyeonsangnsamdo, and grave items such as red-burnished pottery, arrowheads, and stone swords were also discovered. In the case of the red-burnished pottery that was found, it retains a pigment layer with a thickness of about 50 to 160㎛, but with most of the other items, exfoliation and peeling-off of pigment layers can be observed on the surface. The raw materials of the red-burnished pottery contained moderately sorted minerals such as quartz, feldspar, and hornblende, and partly opaque iron oxide minerals were also identified. In particular, the raw materials of the red-burnished pottery from stone coffin tomb #6 were different from those of the other pottery, containing large amounts of hornblende and feldspar. The pottery's red pigment was identified as hematite and showed similar mineral content of raw materials such as fine grained quartz, feldspar, and hornblende. The firing temperature is estimated to have been approximately 900℃, based on their mineral phase. The possibility exists that the raw materials had been collected from the Samdeok-ri area, because diorite and granite diorite with dominant feldspar and hornblende have been identified within 3km of that area. During the pottery manufacturing process, it is estimated that the pigment was painted on the entire surface of the red-burnished pottery after it had been molded and then finished using the abrasion technique. In other words, the red-burnished pottery was made by the process of vessel forming - semi drying - coloring - polishing. The surface and cross-section of the pottery appears differently depending on the concentration of the pigment and the coloring method used after vessels were formed. Most of the excavated pottery features a distinct boundary between pigment and body fabric. However, in the case of pottery in which fine-grained pigments penetrate the body fabric so that layers cannot be distinguished, there is the possibility that the fine-grained pigment layer was applied at a low concentration or immediately after vessel forming. Many cracks can be seen on the surface pigments in thickly painted pottery items, and in many cases, only a small portion of the pigment layers remain due to surface exfoliation and abrasion in the burial environment. It is reported that pottery items may be more easily damaged by abrasion if coated with pigment and polished, so it is believed that the red-burnished pottery of the Samdeok-ri site suffered from weathering in the burial environment. This damage was more extensive in the potsherds that were scattered outside the tomb.

• Journal of Bio-Environment Control
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• v.30 no.1
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• pp.1-9
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• 2021

This study was conducted to examine the changes of photosynthesis, growth, chlorophyll contents and functional material contents in light intensity and EC concentration of wild baby leaf vegetable, Indian lettuce (Lactuca indica L. cv. 'Sunhyang') in DFT hydroponics. The cultivation environment was 25±1℃ of temperature and 60±5% of relative humidity in growth system. At 14 days after sowing, combination effect of light intensity (Photosynthetic Photon Flux Density (PPFD 100, 250, 500 µmol·m-2·s-1) and EC level (EC 0.8, 1.4, 2.0 dS·m-1) of nutrient solution was determined at the baby leaf stage. The photosynthesis rate, stomatal conductance, transpiration rate and water use efficiency of Indian lettuce increased as the light intensity increased. The photosynthesis rate and water use efficiency were highest in PPFD 500-EC 1.4 and PPFD 500-EC 2.0 treatment. The chlorophyll content decreased as the light intensity increased, but chlorophyll a/b ratio increased. Leaf water content and specific leaf area decreased as light intensity increased and a negative correlation (p < 0.001) was recognized. Plant height was the longest in PPFD 100-EC 0.8 and leaf number, fresh weight and dry weight were the highest in PPFD 500-EC 2.0. Anthocyanin and total phenolic compounds were the highest in PPFD 500-EC 1.4 and 2.0 treatment, and antioxidant scavenging ability (DPPH) was high in PPFD 250 and 500 treatments. Considering the growth and functional material contents, the proper light intensity and EC level for hydroponic cultivation of Indian lettuce is PPFD 500-EC 2.0, and PPFD 100 and 250, which are low light conditions, EC 0.8 is suitable for growth.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.535-543
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• 2022

A CPFD (Computational particle fluid dynamics) model of solar fluidized bed receiver of silicon carbide (SiC: average d_p=123 ㎛) particles was established, and the model was verified by comparing the simulation and experimental results to analyze the effect of particle behavior on the performance of the receiver. The relationship between the heat-absorbing performance and the particles behavior in the receiver was analyzed by simulating their behavior near bed surface, which is difficult to access experimentally. The CPFD simulation results showed good agreement with the experimental values on the solids holdup and its standard deviation under experimental condition in bed and freeboard regions. The local solid holdups near the bed surface, where particles primarily absorb solar heat energy and transfer it to the inside of the bed, showed a non-uniform distribution with a relatively low value at the center related with the bubble behavior in the bed. The local solid holdup increased the axial and radial non-uniformity in the freeboard region with the gas velocity, which explains well that the increase in the RSD (Relative standard deviation) of pressure drop across the freeboard region is responsible for the loss of solar energy reflected by the entrained particles in the particle receiver. The simulation results of local gas and particle velocities with gas velocity confirmed that the local particle behavior in the fluidized bed are closely related to the bubble behavior characterized by the properties of the Geldart B particles. The temperature difference of the fluidizing gas passing through the receiver per irradiance (∆T/I_DNI) was highly correlated with the RSD of the pressure drop across the bed surface and the freeboard regions. The CPFD simulation results can be used to improve the performance of the particle receiver through local particle behavior analysis.

• Journal of Plant Biotechnology
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• v.49 no.3
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• pp.240-249
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• 2022

Measuring chlorophyll fluorescence (CF) is a useful tool for assessing a plant's ability to tolerate abiotic stresses such as drought, waterlogging and high temperature. Korean ginseng is highly sensitive to water stress in paddy fields. To evaluate the possibility of non-destructively diagnosing waterlogging stress using chlorophyll fluorescence (CF) imaging techniques, we screened 57 ginseng accessions for waterlogging tolerance. To evaluate waterlogging tolerance among the 2-year-old Korean ginseng accessions, we treated ginseng plants with water stress for 25 days. The physiological disorder rate was characterized through visual assessment (an assigned score of 0-5). The physiological disorder rates of Geumjin, Geumsun and GS00-58 were lower than that of other accessions. In contrast, lines GS97-62, GS97-69 and GS98-1-5 were deemed susceptible. Root traits, chlorophyll content and the reduction rates decreased in most ginseng accessions. Further, these metrics were significantly lower in susceptible genotypes compared to resistant ones. All CF parameters showed a positive or negative response to waterlogging stress, and this response continuously increased over the treatment time among the genotypes. The CF parameter Fv/Fm was used to screen the 57 accessions, and the results showed clear differences in Fv/Fm between the susceptible and resistant genotypes. Susceptible genotypes had an especially low Fv/Fm value of less than 0.8, reflecting damage to the reaction center of photosystem II. It is concluded that Fv/Fm can be used as a CF parameter index for screening waterlogging stress tolerance in ginseng genotypes.

• Journal of Mushroom
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• v.20 no.3
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• pp.138-146
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• 2022

To optimize initial cooling conditions, forced-air cooling was applied to freshly harvested oak mushrooms at 2 levels (0℃ for 30 minutes, at 0℃ for 1 hour) followed by room cooling at 3 levels (-3℃ for 1 day, 0℃ for 1 day, 3℃ for 1 day). After initial cooling, the oak mushrooms were packaged with PVC film, then held in a storage room at 1℃ for 6 weeks. Quality characteristics and percentage marketability were then investigated. As a control, Mushrooms were placed in storage with no initial cooling. The quality factors impacting marketability of fresh oak mushrooms were color change and appearance of decay. Off-odor did not occur or developed only slightly, so it did not affect oak mushroom quality within 6 weeks of low temperature storage. In all treatment groups, the shelf life in which 100% marketability was maintained was up to 3 weeks. At week 5, percent marketability of the 3 treatment groups 1 hour room cooling treatment at 0℃, 1 hour forced air cooling, and control was 100%. 80% In the group that underwent 30 min forced air cooling retained 80% marketability, and the group exposed to 1 day in room cooling at -3℃ retained 86.7% marketability. At week 6 of 1℃ storage, the marketability ratio was 80% in the 1 day room cooling at 0℃ group, 66.7% in the 1 day room cooling at 3℃ group, 46.7% in the 1 hour forced air cooling group, and 33% or less in all other treatment groups. Therefore, the most suitable initial cooling parameter to extend shelf-life of oak mushrooms is 1 day of in room cooling at 0℃ immediately after harvest.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.356-365
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• 2022

Agrivoltaic systems, also called solar sharing, stated from an idea that utilizes sunlight above the light saturation point of crops for power generation using solar panels. The agrivoltaic systems are expected to reduce the incident solar radiation, the consequent surface cooling effect, and evapotranspiration, and bring additional income to farms through solar power generation by combining crops with solar photovoltaics. In this study, to evaluate if agrivoltaic systems are suitable for viticulture, we investigated the microclimatic change, the growth of vines and the characteristics of grape grown under solar panels set by planting lines compared with ones in open vineyards. There was high reduction of wind speed during over-wintering season, and low soil temperature under solar panel compared to those in the open field. There was not significant difference in total carbohydrates and bud burst in bearing mother branches between plots. Despite high content of chlorophyll in vines grown under panels, there is no significant difference in shoot growth of vines, berry weight, cluster weight, total soluble solid content and acidity of berries, and anthocyanin content of berry skins in harvested grapes in vineyards under panels and open vineyards. It was observed that harvesting season was delayed by 7-10 days due to late skin coloration in grapes grown in vineyards under panels compared to ones grown in open vineyards. The results from this study would be used as data required in development of viticulture system under panel in the future and further study for evaluating the influence of agrivoltaic system on production of crops including grapes.