• Journal of the Korean Wood Science and Technology
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• v.9 no.3
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• pp.16-23
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• 1981

This study has been carried out to make a comparative study for the adhesive control methods specifically developed for application to formaldehyde. The method for formaldehyde determination used in this report is the improved chromo tropic acid determination. The results are summarized as follows: 1. The soaking treatment in aqueous solution of urea wok the most scavenging effect on the formaldehyde release from a plywood sample glued with a urea formaldehyde adhesive, and other removal treatment such as resorcinol, albumine-, and hardener-treatment gave significant reduction too. 2. In glue shear strength of dry test, 2% of resorcinol treatment and soaking treatment showed the highest strength and all the other treatment met the standard, but in hot water soaking test, 2% of resorcinol treatment gave the best results, on the other hand, adding the hardener showed the lowest strength and failed in meeting the standard. 3. Air dried moisture content of all treated plywood met the standard which calls for 13% or bellow. 4. In this comparative study, we can make a strong combination each other or go into the details of one treatment for the best result through the more study.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.178-183
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• 2008

This study investigated the effects of osmotic dehydration (OD) and vacuum impregnation (VI) on the quality of dried apple products. Weight reduction and water loss increased during OD, but these decreased in the apples during VI. In particular, VI's effect on increasing solid gain was superb. For apples in 40% sucrose solution, OD and VI were followed by hot-air drying at 50$^{\circ}C$. The experimental data were fitted successfully using the modified Page model. OD and VI increased drying time and decreased the drying rate constant of these apples as compared to the control. Shrinkage and rehydration capacity greatly decreased in the apples dried by OD and increased in the apples dried by VI as compared to the control. OD also decreased titratable acidity and ascorbic acid content considerably. Sensory evaluations of the products indicated that the apples prepared by OD had higher palatability in their rehydrated form in yoghurt, and the apple products prepared by VI had higher palatability in their dried form.

• Journal of agriculture & life science
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• v.44 no.6
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• pp.15-22
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• 2010

This study was carried out to investigate the characteristics of ions in rainwater by stem flow, through fall and rainfall in Pinus thunbergii forest in Ulsan industrial complex area and Mt. Jiri area. pH of rainwater in Ulsan industrial complex area was low as compared with those in Mt. Jiri area. EC of rainwater in Ulsan industrial complex area was mainly high and there was twice difference in stemflow and through fall as compared to Mt. Jiri area. The concentration of major ions in rainwater, especially $Ca^{2+}$ and $Mg^{2+}$ in stem flow were generally high at Ulsan industrial complex area, while anions were high in the order of ${SO_4}^{2-}>{NO_3}^{-}>Cl^-$ in both areas. There was a wide difference in ${SO_4}^{2-}$ concentration in the stem flow between both areas. ${SO_4}^{2-}$ from air pollutants will result into acidification of forest soils and thereafter cause damages on forest ecosystems.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.613-620
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• 2021

A flow channel shape of PEMFC has an influence on the internal flow uniformity. If the reactant distribution in a flow path is not uniform during operation, both catalyst deactivation and mechanical damage of membrane could occur resulting in decreasing the membrane electrode assembly (MEA) durability. Numerous studies concerning flow design have been conducted to make smooth supply and uniform distribution of reactants in fuel cells. The baffle of flow path could improve fuel cell performance through the forced convection effect. A sub-channel, as an additional air flow path, could increase the reactant concentration and reduce the mass transfer loss via a smooth water discharge. In this study, computational fluid dynamics (CFD) was used to analyze the effect of blocks and sub-channels on the current density and oxygen concentration of the fuel cell. As a result, the limit current density and oxygen concentration at a rear block increased when using blocks and sub-channels in a flow channel. In particular, the current density increased significantly when the sub-channel was placed between two blocks. Also, the sub-channel position was optimized by analyzing the oxygen concentration, and the oxygen concentration was recovered at a rear block in the fuel cell.

• Korean Chemical Engineering Research
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• v.59 no.1
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• pp.60-67
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• 2021

This study presented techno-economic analysis of a 500 MWe oxy-coal power plant with CO2 capture. The power plant included a circulating fluidized-bed (CFB), ultra-supercritical steam turbine, flue gas conditioning (FGC), air separation unit (ASU), and CO2 processing unit (CPU). The dry flue gas recirculation (FGR) was used to control the combustion temperature of CFB. One FGR heat exchanger, one heat exchanger for N2 stream exiting ASU, and a heat recovery from CPU compressor were considered to enhance heat efficiency. The decrease in the temperature difference (ΔT) of the FGR heat exchanger that means the increase in heat recovery from flue gas enhanced the electricity and exergy efficiencies. The annual cost including the FGR heat exchanger and FGC cooling water was minimized at ΔT = 10 ℃, where the electricity efficiency, total capital cost, total production cost, and return on investment were 39%, 1371 M$, 90 M$, and 7%/y, respectively.

• The Journal of Korean Society for Radiation Therapy
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• v.21 no.2
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• pp.75-82
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• 2009

Purpose: Measure the ozone level in the treatment room while treating a patient so want to know the degree of contamination caused by ozone occurrence. Materials and Methods: Use the linear accelerator (Clinac 21EX, Varian, USA) with the ozone meter (series-200, aeroQual, New Zealand) and water phantom (Wellhofer, IBA, Germany) is irradiated the radiation so that measured the ozone generation level according to MU, dose-rate, SSD, field size, energy, delay time and put the ozone meter in the treatment room actually while treating a patient so measured the daily ozone level variation. Results: While irradiating the radiation, degree of ozone contamination wasn't affected by the energy but mostly in case of electron beam, ozone level was higher than photon beam. The higher dose-rate (0.016~0.025 ppm/hr), the farther SSD (0.018~0.030 ppm/hr), the wider field sizes (0.016~0.025 ppm/hr), the more MU (0.018~0.046 ppm/hr), it occurred high ozone level. Ozone decrement according to delay time changed the background level (0.016 ppm/hr) after elapsed time of 10 minutes from irradiating radiation. And daily ozone occurrence level in the treatment room was below ozone standard level 0.1 ppm/hr (average:0.06 ppm/8 hr) but it could confirm that ozone generation level was included the level (max:0.038 ppm/hr) above 0.02 ppm/hr which patient could perceive. Conclusion: Through ozone level according to variation of certain conditions, actually in the treatment room ozone generation level didn't damaged to patients or workers. Commonly peoples think that ozone was harmful gas but it thought that small amount of ozone generation level while treating a patient was beneficial in the treatment room through air purge action of pathogenic germ or virus sterilization.

• Microbiology and Biotechnology Letters
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• v.41 no.4
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• pp.449-455
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• 2013

Human skin is constantly exposed to environmental conditions such as UV rays, polluted air, and chemical products. UV rays, in particular, affect skin in many ways causing wrinkles, fine wrinkles, rough skin, and xeroderma through a skin aging process. The purpose of this study was to investigate the anti-wrinkling effect of Juniperus rigida Sieb., derived from a common cedar tree found the world over. Measuring the elastase to investigate wrinkling efficacy, it was shown that at a concentration level of $1,000{\mu}g/ml$ of the two extracts, the water extract exhibited a lower than 10% inhibition activity, while the ethanol extract exhibited a 68.5% inhibition activity. Collagenase inhibition activity in the water extract and ethanol extract were 44.9% in the former and 97.2% in the latter extract, which in the case of the ethanol extract, is similar to ascorbic acid (99.6%). Moreover, measuring the biosynthesis of collagen by fibroblast, a concentration level of $50{\mu}g/ml$ of ethanol extract produced 151.52% of biosynthetic promotion, proving that the ethanol extract acts as a superb anti-wrinkling agent. The result of an investigation conducted on the influence of the ethanol extract on MMP-1 caused by UVA showed that at a concentration level of $1,00{\mu}g/ml$ of the ethanol extract of J. rigida Sieb a 67.1% inhibition activity was noted. At a concentration level of $50{\mu}g/ml$ of the ethanol extract of J. rigida Sieb a 35% and 39% inhibition ratio to MMP-1 protein and mRNA were observed respectively, thereby restraining the appearance of the collagen breakdown enzyme MMP-1 and wrinkle creation by skin photo-aging.

• Korean Journal of Plant Resources
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• v.25 no.1
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• pp.156-168
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• 2012

Chrysanthemum is a cut flower species that normally lasts for 1 to 2 weeks, in some cases 3-4 weeks. This has been attributed to low ethylene production during senescence. Reduction in cut flower quality has been attributed to the formation of air embolisms that partially or completely blocks the water transport from the vase solution to the rest of the cut flower stem, increasing hydraulic resistance which may cause severe water stress, yellowing, wilting of leaf, and chlorophyll degradation. Standard type chrysanthemum can be harvested when buds were still tightly closed and then fully opened with the simple bud-opening solution. Standard type chrysanthemum can also be harvested when the minimum size of the inflorescence is about 5-6 cm bud which opened into the first flower full-sized flower. While spray varieties can be harvested when 2-4 most mature flowers have opened (40% opening). Cut flowers are sorted by stem length, weight, condition, and so on. Standard chrysanthemum is 80 cm length for standard type and 70cm for spray type. Pre-treatment with a STS, plant regulator such as GA, BA, 1-MCP, chrysal, germicide, and sucrose, significantly improved the vase life and quality of cut flowers. It is well established that vase solutions containing sugar can improve the vase life of cut chrysanthemum. Chrysanthemum is normally packed in standard horizontal fiberboard boxes. Chrysanthemum should normally be stored at $5{\sim}7^{\circ}C$. Precooling resulted in reduction in respiration, decomposition, and transpiration activities as well as decoloration retardation. There was significant difference between "wet" storage in 3 weeks and "dry" storage in 2 weeks. In separate pulsing solution trials, various germicides were tested, as well as PGRs to maintain the green color of leaves and turgidity. Prolonging vase life was attained with the application of optimal solution such as HQS, $AgNO_3$, GA, BA and sucrose. This also retarded senescence in leaves of cut flower stems. Fresh cut chrysanthemum can be transported using a refrigerated van with $5{\sim}7^{\circ}C$. Increasing consumption and usage of cut chrysanthemum of various cultivars would require efficient transport system, and effective information exchange among producer, wholesaler, and consumer.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.715-728
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• 2023

Tracksite of pterosaurs, birds, and dinosaurs in Chungmugong-dong in Jinju was designated as a natural monument in 2011 and is known as the world's largest in terms of the number and density of pterosaur footprints. This site has been managed by installing protection buildings to conserve in 2018. About 17% of the footprints of pterosaur, theropod, and ornithopod in this site under management in the 2nd protection building are of great academic value, but observation of footprints has difficulties due to continuous physical and chemical damage. In particular, the accumulation of milk-white contaminants is formed by the gypsum and air pollutant complex. Gypsum remains evaporated with a plate or columnar shape in the process of water circulation around the 2nd protection building, and the dust is from through the inflow of the gallery windows. The aqueous solution of gypsum, consisting of calcium from the lower bed and sulfur from grass growth, is catchmented into the groundwater from the area behind the protection building. Pollen and a few minerals other constituents of contaminants, go through the gallery window, which makes it difficult to expel dust. To conserve the fossil-bearing beds from two contaminants of different origins, controlling the water and atmospheric circulation of the 2nd protection building and removing the contaminants continuously is necessary. When cleaning contaminants, the steam cleaning method is sufficiently effective for powder-shaped milk-white contaminants. The fossil-bearing bed consists of dark gray shale with high laser absorption power; the laser cleaning method accompanies physical loss to fossils and sedimentary structures; therefore, avoiding it as much as possible is desirable.

• Economic and Environmental Geology
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• v.45 no.3
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• pp.217-235
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• 2012

We evaluated the geochemical characteristics and their potential pollution of Asian Dusts in Daejeon, Korea during spring 2007. Compared with the chemical compositions of soils in source area of Asian Dust, those of aerosols in Daejeon were enriched with trace elements (ten to hundred fold), inferring that pollutants from China have affected on local environment in adjoining country such as Korea. Chemical analysis of aerosols during Asian dust showed that fine particles ($PM_{2.5}$) contained high contents of trace elements such as Cr, Cu, Pb, Zn, V, S, As, Cd, Co, Ni, Mo, Sb, Cs, Rb, Th, Sc and Y. In the case of TSP (Total Suspended Particle), Zr, Sr, Ba, Li, Th and U were contained much more than other trace elements. The contents of some elements (i.e. Li, Cs, Co, U, Cr, Ni, Rb, V, Th, Y, Sr and Sc) in aerosols collected in Asian Dust period, which are not likely enriched by air pollutants, were higher (2 - 4.2 fold) than those in Non Asian Dust period, indicating that these elements could be used as indicator elements for determining the occurrence of Asian Dust phenomena (especially, Sr, V, Cr & Li). In the case of Asian Dust coming through the big cities and/or industrial areas of China, the domestic aerosols had higher contents of trace elements (such as S, Cd, Zn, Pb, Cu, Mo and As) than those from Northeastern China via North Korea, indicating that the transportation courses of air mass are very important to determine the pollution degrees. Using the enrichment factors of trace elements in aerosols during Asian Dust and Non Asian Dust, we identified that some elements (i.e. S, Zn, Cu, Pb, As, Mo and Cd) were most problematic in terms of environmental hazard aspects, and these elements could affect adverse effects on human health as well as ecosystem and surface environment (soil and water) through long-lived precipitation.