• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.11-25
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• 2015

The accident at Japan's Fukushima Daiichi nuclear power plant in March 2011, caused by an earthquake and a subsequent tsunami, resulted in a failure of the power systems that are needed to cool the reactors at the plant. The accident progression in the absence of heat removal systems caused Units 1-3 to undergo fuel melting. Containment pressurization and hydrogen explosions ultimately resulted in the escape of radioactivity from reactor containments into the atmosphere and ocean. Problems in containment venting operation, leakage from primary containment boundary to the reactor building, improper functioning of standby gas treatment system (SGTS), unmitigated hydrogen accumulation in the reactor building were identified as some of the reasons those added-up in the severity of the accident. The Fukushima accident not only initiated worldwide demand for installation of adequate control and mitigation measures to minimize the potential source term to the environment but also advocated assessment of the existing mitigation systems performance behavior under a wide range of postulated accident scenarios. The uncertainty in estimating the released fraction of the radionuclides due to the Fukushima accident also underlined the need for comprehensive understanding of fission product behavior as a function of the thermal hydraulic conditions and the type of gaseous, aqueous, and solid materials available for interaction, e.g., gas components, decontamination paint, aerosols, and water pools. In the light of the Fukushima accident, additional experimental needs identified for hydrogen and fission product issues need to be investigated in an integrated and optimized way. Additionally, as more and more passive safety systems, such as passive autocatalytic recombiners and filtered containment venting systems are being retrofitted in current reactors and also planned for future reactors, identified hydrogen and fission product issues will need to be coupled with the operation of passive safety systems in phenomena oriented and coupled effects experiments. In the present paper, potential hydrogen and fission product issues raised by the Fukushima accident are discussed. The discussion focuses on hydrogen and fission product behavior inside nuclear power plant containments under severe accident conditions. The relevant experimental investigations conducted in the technical scale containment THAI (thermal hydraulics, hydrogen, aerosols, and iodine) test facility (9.2 m high, 3.2 m in diameter, and $60m^3$ volume) are discussed in the light of the Fukushima accident.

• Nuclear Engineering and Technology
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• v.41 no.4
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• pp.531-544
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• 2009

This paper is intended to provide key issues and current research outcomes on accelerator-based Boron Neutron Capture Therapy (BNCT). Accelerator-based neutron sources are efficient to provide epithermal neutron beams for BNCT; hence, much research, worldwide, has focused on the development of components crucial for its realization: neutron-producing targets and cooling equipment, beam-shaping assemblies, and treatment planning systems. Proton beams of 2.5 MeV incident on lithium target results in high yield of neutrons at relatively low energies. Cooling equipment based on submerged jet impingement and micro-channels provide for viable heat removal options. Insofar as beam-shaping assemblies are concerned, moderators containing fluorine or magnesium have the best performance in terms of neutron accumulation in the epithermal energy range during the slowing-down from the high energies. NCT_Plan and SERA systems, which are popular dose distribution analysis tools for BNCT, contain all the required features (i.e., image reconstruction, dose calculations, etc.). However, detailed studies of these systems remain to be done for accurate dose evaluation. Advanced research centered on accelerator-based BNCT is active in Korea as evidenced by the latest research at Hanyang University. There, a new target system and a beam-shaping assembly have been constructed. The performance of these components has been evaluated through comparisons of experimental measurements with simulations. In addition, a new patient-specific treatment planning system, BTPS, has been developed to calculate the deposited dose and radiation flux in human tissue. It is based on MCNPX, and it facilitates BNCT efficient planning based via a user-friendly Graphical User Interface (GUI).

• Korean Journal of Veterinary Service
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• v.30 no.3
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• pp.291-304
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• 2007

Mutants of an obligate aerobic bacterium, Vitreoscilla, that have deficiency in heat-labile catalase-peroxidase hydroperoxidase I (HPI) were created by EMS treatment. The catalase-peroxidase HPI-deficient mutant showed substantially lower peroxidase activity in exponential and mid-stationary phase compared with the wild type strain. In late stationary phase, the mutant exhibited no peroxidase activity. Peroxidase deficiency in the mutant was revealed by polyacrylamide gels stained for peroxidase activity. Characteristically, catalase levels in the mutant increased about 14- and 8-fold during growth in the exponential and stationary phases, respectively, compared to those in the wild type, suggesting a compensatory effect for protection from $H_2O_2$ toxicity. The mutant showed differences in physiology from the wild type: retardation in growth rate and decrease in oxygen consumption. Both the wild type and the catalase-peroxidase HPI-deficient mutant of Vitreoscilla had lower growth rates in media containing increasing $H_2O_2$ concentrations. However, the mutant exhibited an additionally decreased growth rate after 6 to 8 h of growth compared to the wild type. The wild type was resistent up to 20 mM $H_2O_2$, whereas the mutant was very sensitive to high concentrations of exogenous $H_2O_2$. Although elevated catalase levels would provide protection of the bacteria from the deleterious effect of $H_2O_2$, it did not appear to be complete. Cell-free extracts of the mutant showed decreased NADH oxidation rates and higher accumulation of $H_2O_2$ during this oxidation. These results may account for the impaired growth and earlier onset of death phase by the catalase-peroxidase HPI-deficient mutant of Vitreoscilla.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.661-664
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• 2008

As architectures have recently become high-risers and megastructured, stable high strength products have been ensured. Accordingly, use of precast concrete accouplement has been increased in order to facilitate air compression and rationalize construction. Since not only external heating but also internal temperature rise caused by the accumulation of cement hydration heat in manufacturing process, precast concrete members with large cross-section used for high-rise mega-structure's columns and beams may exhibit different temperature history compared to the precast concrete members for wall and sub-floor with relatively small cross-sections. Therefore, this study aims to elucidate the characteristics of temperature history of mass concrete members cast with high-strength concrete for precast concrete application. In this study, large cross-sectional precast concrete mock-up, unit cement quantity, and temperature histories in manufacturing precast concrete member under different curing condition were inclusively investigated.

• The Korean Journal of Zoology
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• v.31 no.3
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• pp.207-217
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• 1988

A myotrophic protein that seemed to he eseentiai for the hision of chick embryonic myoblasts in culture was isolated from chick embryo extrad and was found to be identical or at least similar to the iron-transporting protein, transferrin. Embryo extract seemed to contain, in addition to this myotrophic protein, a heat stable protein that inhibits the fusion of myoblasts. Iron seemed to he necessary for myoblasts to fuse and it was supposed that the role of the myotrophic protein m myoblast fusion is to supply iron to the cell. The numher of the myotrophic protein receptors on myoblast surface membrane decreased immediately after the start of myoblast fusion, supposedly due to the decreased need of iron after the fusion once commenced. It was estimated that endocytosis of myotrophic protein took about 10 minutes and one recycling about 2 hours. The accumulation of iron in myoblasts continued linearly with cultre time and endocytosis of the myotrophic protein occured at a constant rate.

• The Korean Journal of Zoology
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• v.39 no.1
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• pp.12-20
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• 1996

A multipotential hematopojetic cell line, 1(562 cell, was differentiated into megakaryocyte by a chemical inducer, PMA, with an enhanced expression of gpIlla accompaning with a distinct morphological change. On the other hand, 1(562 cells were differentiated into erythrocytes by other chemical inducers, DMSO or butyrate, with a concomitant increase in hemoglobin accumulation. An antigen of apparent molecular weight of 61 kDa was identified on the surface of 1(562 cells by using monoclonal antibody raised against 1(562 cells. The antigen was considered to be a glycoprotein molecule rich in sialic acids and the epitope of antigen was sensitive to neuraminidase digestion or peroxidase oxidation, but resistant to heat treatment. The 61 kDa surface antigen was increased or decreased in its expression along differentiation of 1(562 cells into megakaryocytes or erythrocytes, respedively.

• Journal of Korea Water Resources Association
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• v.47 no.1
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• pp.49-62
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• 2014

As the Urban area grows and more land is developed both within the city and in surrounding areas, hydrologic functions of the natural water cycle are altered. Urbanization creates impervious areas that negatively impact stormwater runoff characteristics. these changes to the natural hydrologic cycle result in the increased flooding, decreased groundwater recharge, increased urban heat island effects. Finally, the land use and other activities result in accumulation and washoff of pollutants from surface, resulting in water quality degradation. Therefore, in this study, evaluating and quantitative analysis of the percolation effect through infiltration experiment of permeable pavement, which is one of the ways that can reduce the problem of the dry stream. Also the SWMM model is used to study the effect of the hydrologic cycle for permeable pavement block contribution.

• Molecules and Cells
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• v.38 no.2
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• pp.187-194
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• 2015

Thioredoxin (TRX) is a disulfide reductase present ubiquitously in all taxa and plays an important role as a regulator of cellular redox state. Recently, a redox-independent, chaperone function has also been reported for some thioredoxins. We previously identified nodulin-35, the subunit of soybean uricase, as an interacting target of a cytosolic soybean thioredoxin, GmTRX. Here we report the further characterization of the interaction, which turns out to be independent of the disulfide reductase function and results in the co-localization of GmTRX and nodulin-35 in peroxisomes, suggesting a possible function of GmTRX in peroxisomes. In addition, the chaperone function of GmTRX was demonstrated in in vitro molecular chaperone activity assays including the thermal denaturation assay and malate dehydrogenase aggregation assay. Our results demonstrate that the target of GmTRX is not only confined to the nodulin-35, but many other peroxisomal proteins, including catalase (AtCAT), transthyretin-like protein 1 (AtTTL1), and acyl-coenzyme A oxidase 4 (AtACX4), also interact with the GmTRX. Together with an increased uricase activity of nodulin-35 and reduced ROS accumulation observed in the presence of GmTRX in our results, especially under heat shock and oxidative stress conditions, it appears that GmTRX represents a novel thioredoxin that is co-localized to the peroxisomes, possibly providing functional integrity to peroxisomal proteins.

• Journal of Biosystems Engineering
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• v.32 no.4
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• pp.247-255
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• 2007

During the winter season in Korea, the relative humidity of greenhouse at night often exceeds 90% because air temperature inside the greenhouse is usually controlled using a heater with all of windows closed to minimize heat loss, thereby requiring the use of a dehumidifier that can maintain optimum humidity levels of $70{\sim}80%$ to provide a good growth condition of crops. Also, such a high humid condition can cause the development of a pest, such as insects, fungi or diseases. However, the use of most conventional dehumidifiers for low temperature dehumidification is limited because their performance is degraded due to frost accumulation on the evaporator coil. This study was carried out to develop a refrigeratory-based dehumidifier suitable for low temperature dehumidification in greenhouse cultivation. The developed dehumidifier consists of a condenser and an evaporator installed separately so that relative and absolute humidity levels can be reduced when air passed through the condenser and evaporator, respectively. The prototype dehumidifier showed a dehumidification capacity of $5{\sim}7kg/h$ when air with a temperature of $15{\sim}25^{\circ}C$ and a relative humidity of $70{\sim}95%$ came into the dehumidifier. Under the condition that either temperature or relative humidity was fixed, the amount of condensed water was proportional to the levels of both temperature and relative humidity.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.465-469
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• 2006

Two mesophilic trickling bed bioreactors filled with two different types of media, hydrophilic- and hydrophobic-cubes, were designed and tested for hydrogen production via anaerobic fermentation of sucrose. Each reactor consisted of a column packed with polymeric cubes and inoculated with heat-treated sludge obtained from anaerobic digestion tank. A defined medium containing sucrose was fed with changing flow rate into the capped reactor, hydraulic retention time and recycle rate. Hydrogen concentrations in gas-phase were constant, averaging 40% for all conditions tested. Hydrogen production rates increased up to $10.5 L{\cdot};h^{-1}{\cdot}L^{-1}$ of reactor when influent sucrose concentrations and recycle rates were varied. Hydrophobic media provided higher value of hydrogen production rate than hydrophilic media at the same operation conditions. No methane was detected when the reactor was under a normal operation. The major fermentation by-products in the liquid effluent of the both trickling biofilters were acetate and butyrate. The reactor filled with hydrophilic media became clogged with biomass and bio gas, requiring manual cleaning of the system, while no clogging occurred in the reactor with hydrophobic media. In order to make long-term operation of the reactor filled with hydrophilic media feasible, biofilm accumulation inside the media in the reactor with hydrophilic media and biogas produced from the reactor will need to be controlled through some process such as periodical backwashing or gas-purging. These tests using trickling bed biofilter with hydrophobic media demonstrate the feasibility of the process to produce hydrogen gas in a trickle-bed type of reactor. A likely application of this reactor technology could be hydrogen gas recovery from pre-treatment of high carbohydrate-containing wastewaters.