• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3543-3548
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• 2023

Shutdown chemistry evolution is performed in nuclear power plants at each refueling outage (RFO) to establish safe conditions to open system and minimize inventory of corrosion products in the reactor coolant system (RCS). After hydrogen peroxide is added to RCS during shutdown chemistry evolution, corrosion products are released and are removed by filters and ion exchange resins in the chemical volume control system (CVCS). Shutdown chemistry evolution including RCS clean-up time to remove released corrosion products impacts the critical path schedule during RFOs. The estimation of clean-up time prior to RFO can provide more reliable actions for RCS clean-up operations and transients to operators during shutdown chemistry. Electric Power Research Institute (EPRI) shutdown calculator (SDC) enables to provide clean-up time by Co-58 peak activity through operational data from nuclear power plants (NPPs). In this study, we have investigated the results of EPRI SDC by shutdown chemistry data of Co-58 activity using NPP data from previous cycles and modeled the estimated clean-up time by EPRI SDC using average Co-58 activity of the NPP. We selected two RFO data from the NPP to evaluate EPRI SDC results using the purification time to reach to 1.3 mCi/cc of Co-58 after hydrogen peroxide addition. Comparing two RFO data, the similar purification time between actual and computed data by EPRI SDC, 0.92 and 1.74 h respectively, was observed with the deviation of 3.7-7.2%. As the modeling the estimated clean-up time, we calculated average Co-58 peak concentration for normal cycles after cycle 10 and applied two-sigma (2σ, 95.4%) for predicted Co-58 peak concentration as upper and lower values compared to the average data. For the verification of modeling, shutdown chemistry data for RFO 17 was used. Predicted RCS clean-up time with lower and upper values was between 21.05 and 27.58 h, and clean-up time for RFO 17 was 24.75 h, within the predicted time band. Therefore, our calculated modeling band was validated. This approach can be identified that the advantage of the modeling for clean-up time with SDC is that the primary prediction of shutdown chemistry plans can be performed more reliably during shutdown chemistry. This research can contribute to improving the efficiency and safety of shutdown chemistry evolution in nuclear power plants.

• Economic and Environmental Geology
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• v.57 no.4
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• pp.387-396
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• 2024

The geological disposal of high-level radioactive waste (HLW) involves permanently isolating the wastes in stable geological formations deep underground. Mudstone (siltstone and claystone) containing abundant clay minerals is proposed as a host rock for geological disposal of HLW because clay minerals have low permeability and high ion sorption/exchange capacity. Despite the widespread occurrence of sedimentary basins in Korea, there is a lack of evaluation of mudstone as host rocks for geological disposal. In this study, we utilized the JBH-1 borehole (7-754 m) obtained from the Jinju Formation to investigate the distribution trend and mineral compositions of mudstone. Additionally, we conducted comparative analyses with the Opalinus Clay in Switzerland considered as host rock of geological disposal of HLW. Claystone containing more than 40% clay minerals exhibit thick layers primarily in the upper section (7-350 m) of the JBH-1 borehole. While the clay minerals content of claystone does not show significant variation with depth, there are differences in the characteristics of feldspar and carbonate minerals. These mineralogical variations can led change in pore water chemistry and rock mechanical properties. The clay minerals content of claystone in the Jinju Formation is similar to that of the Opalinus Clay. However, there are notable differences in clay minerals composition. While the Opalinus Clay contains smectite-illite mixed-layer minerals, the Jinju Formation are dominated by illite indicating higher burial temperatures. This information will be useful for studying the host rock of HLW geological disposal site in Korea.

• The Korean Journal of Pharmacology
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• v.31 no.1 s.57
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• pp.39-51
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• 1995

The roles of ${\beta}-adrenoceptor$ were well known in hyperthyroidal heart, but not with ${\alpha}-adrenoceptor$. So we studied the effects of phenylephrine on membrane potential, intracellular sodium activity ($a^{i}_{Na}$), twitch force, and intracellular pH ($pH_i$) by continuous intracellular recordings with ion-selective and conventional microelectrodes in the papillary muscles of hyperthyroid guinea pig heart. ${\alpha}_1-adrenoceptor$ stimulation by phenylephrine (10^{-5}\;or\;3{\times}10^{-5}M$) produced the following changes: variable changes in action potential duration, a hyperpolarization ($1.5{\pm}0.1mM$) of the diastolic membrane potential, an increase in $a^{i}_{Na}\;(0.4{\pm}0.15mM)$, a stronger positive inotropic effect ($220{\pm}15%$), an increase in $pH_i\;(0.06{\pm}0.002\;unit)$. These changes were flocked by prazosin and atenolol. This indicated that the changes in membrane potential, $a^{i}_{Na}$ twitch force, and $pH_i$ are mediated by a stimulation of the ${\alpha}_1-adrenoceptor$. Ethylisopropylamiloride ($10^{-5}$) also blocked the increase in $a^{i}_{Na}$ and twitch force. On the other hand, strophanthidin, tetrodotoxin, $Cs^+$ or verapamil did not block the increase in $a^{i}_{Na}$ and twitch force. Thus, it was suggested that ${\alpha}_1-adrenoceptor$ stimulation increased $a^{i}_{Na}\;and\;pH_i$ by stimulation of $Na^{+}-H^{+}$ exchange, thereby allowing intracellular alkalinization and $a^{i}_{Na}$ increase. These results were very different from euthyroidal heart which showed ${\alpha}_1-adrenoceptor$-induced decrease in $a^{i}_{Na}$ and initial negative inotropic effect. From the above results, it was concluded that ${\alpha}_1-adrenoceptor$ had a important role in hyperthy-roidal heart.

• Korean Journal of Agricultural Science
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• v.21 no.2
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• pp.122-132
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• 1994

Bacteriostatic activity of secretory immumoglobulin A (SIgA) in human and bovine colostrums on enterotoxigenic type Salmonella was tested in the tissue culture medium. SIgA was used in $0.1{\sim}5.0mg/m{\ell}$ concentration with or without the addition of egg lysozyme tested for theirs bacteriostatic activites. 1. Bovine SIgA rich fraction with a large amount of $IgG_1$-dimer could be prepared from bovine colostrum of Holstein cows by anion exchange chromatography using DEAE-Sephadex A-50 and gel filtration on Sephadex G-200 and Sepharose 6B. 2. Human SIgA appeared to be the most bacteriostatic effect for all varieties of Salmonella in a range of $0.5{\sim}1.0mg/m{\ell}$ Bovine SIgA showed a marked bacteriostatic effect increased by increasing the concentration. Bovine IgG had not show bacteriostatic effect against both enterotoxigenic type Salmonella. Egg lysozyme as well as bovine SIgA also showed a marked bacteriostatic effect increased by increasing the concentration. 3. When the growth inhibition of human SIgA was tested by adding egg lysozyme with time interval, egg lysozyme showed bacteriostatic effect as compared with control. But human SIgA and adding with lysozyme showed slight the bacteriostatic effect. 4. When the growth inhibition of bovine SIgA was tested by adding egg lysozyme with time interval, all treatment against S. enteritidis showed bacteriostatic effect as compared with control In the case of S. typhinwrium, egg lysozyme showed a marked bacteriostatic effect as compared with control.

• Journal of Korean Society of Forest Science
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• v.84 no.1
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• pp.103-113
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• 1995

To estimate buffer capacity and sensitivity of forest ecosystem to acid rain in Taejon, ionic components of throughfall, stemflow, soil leachate, and open rain in Pinus rigida and Quercus variabilis forest were analysed. The spatial sensitivity based on parent rock and forest type was given by IDRISI of GIS which created imagery conversion from soil and vegetation map. Parent rocks and soils were classified into acidic, sedimentary, metamorphic rock and then subdivided based on $SiO_2$ content. Average pH of vegetation leachate was higher in throughfall but lower in stemflow than open rain and higher in Quercus variabilis forest than in Pinus rigida forest. The flow of $SO{_4}^{2-}$, $NO_3{^-}$ and $Cl^-$ through vegetation leaching(throughfall plus stemflow) into soil were 7.2, 4.3, and 2.5 times, respectively, higher in Pinus rigida forest and 4.4, 2, and 2.5 times, respectively, higher in Quercus variabilis forest than in open field. But the concentration of exchangeable cations was 4.1 times higher in Pinus rigida forest and 4.6 times higher in Quercus variabilis forest than in open field. Average pH of soil leachate was lower than that of throughfall, but higher than that of stemflow. The concentration of exchangeable canons and $Al^{3+}$ in soil leachate were more in Pinus rigida forest than in Quercus variabilis forest and increase signficantly with the increase of acidic deposits. Pinus forest had more deposition and canopy interception of acidic pollutants and more nutrient loss than Quercus forest, and Quercus forest had more cation exchange and proton consumption and than consequently had less nutrient loss and better buffer capacity than Pinus forest. The 69% of forest soils was distributed on acidic rock, 25% of it on metamorphic rock, and 6% of it on intermediate and basic rock. Acidic rock residuals which had low very canon exchange capacity and high sensitivity to acid rain occupied a half of total forest land in Taejon area. Therefore forests in Taejon showed high vulnerability to acid rain and will receive much more stress with the increase of acid rain precursors.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.323-330
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• 1998

Cyclodextrin glucanotransferase (CGTase) was purified from the culture broth of the Bacillus firmus var. alkalophilus, using ultrafiltration, starch adsorption/desorption, ion-exchange chromatography on DEAE-cellulose and gel filtration on Sephacryl HR-100. The molecular weight of the purified enzyme was determined as 77,000 by SDS-PAGE. The optimum pH and temperature for the CD synthesis were 6.0 and 5$0^{\circ}C$, respectively. The activity of this enzyme was stably kept at the range of pH 6.0～9.5 and up to 5$0^{\circ}C$. However, in the presence of $Ca^{2+}$, the optimum temperature for CD synthesis was shifted 55~6$0^{\circ}C$ and this enzyme was stable up to 6$0^{\circ}C$ because of the stabilizing effect of $Ca^{2+}$. The purified CGTase produced CDs with high conversion yields of 45~51% from sweet potato starch, com starch and amylopectin as substrate, especially, and the product ratio of $\beta$-CD to ${\gamma}$-CD was obtained at range of from 5.8:1 to 8.4:1 according to the kind of substrate. The purified enzyme produced mainly $\beta$-CD without accumulation of $\alpha$-CD during enzyme reaction using various starches as the substrate, indicating that the purified enzyme is the typical $\beta$-CGTase. The purified CGTase produced 25 g/l of CDs from 5.0% (w/v) liquefied com starch and the conversion yield of CDs was 50%, and the content of $\beta$-CD was 84% of total CDs after 8 hours under the optimum reaction condition.ion.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.3
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• pp.153-170
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• 1977

Considering the ways for the possible improvement of soil test for upland crops, various methods for the evaluation of K supplying power and testing of available soil K were reviewed in terms of theoretical principles and practical usefulness of the each method. The review was also made on the characteristics of upland crops in K requirement and on the chemical properties of major korean upland and lowland rice soils in terms of K availability. Following is the few remarks drawn from the review. 1. Quite large number of methods have been known for the evaluation of K supplying power and testing for available soil K. In nature, they can be divided into two categories; capacity-based methods and intensity-based methcds. The capacity-based methods usually measure the exchangeable and some portion of nonexchangeable K, while the intensity-based methods suggest to consider the ractivity ratios of major cations in soil solution and the energy requirement for the replacement of exchangeable soil K into soil solution. 2. As methodology for extraction of interested part of soil K, chemical extraction, electrodialysis and ion exchange methods have been known. Among these, chemical extract ion is favorable because of its simplicity. However, recently suggested Electro-Ultra-Filtration method seems to merit further study for wider use for not only K but also other nutrient availability of soils. 3. The intensity-based methods, although they are more theoretical, because of their complexity, in methods may not be adapted for practical soil tests. 4. The exchangeable K which is rather simple to measure and which well reflects the status of K reserve as nonexchangeable and is immediate pool of water soluble K may be good, if not best, criterion of soil K availability to plant in common soil testing. 5. Because there are evidences that the abundance of available K alone may not be good inclication for availability of K to plant, it is recommendable to interprete the exchangeable K data as percent saturation of exchangeable K to total C. E. C. of soil for the recommend ation of K fertilizer based on soil tests. 6. Some pot and field trial results showed the trends that percent potassium saturation to total C. E. C. better serve as the parameter for K fertilizer recommendation.

• Journal of the Korean Chemical Society
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• v.34 no.2
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• pp.143-158
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• 1990

Metal complexes were prepared by reacting uranium (Ⅵ), thorium (Ⅳ) and rare earth metal (Ⅲ) ions including Nd (Ⅲ), Sm (Ⅲ) and Ho (Ⅲ) with macrocyclic ligands including five crown ethers, nine crownands and one cryptand ligands, and subjected to NMR studies in order to examine coordination sites of the ligands and compositions of the complexes formed. Among the marcocyclic ligands, crown ethers and crownand ligands have shown down-field shifts of the methylene protons of the lcigands by forming stable complexes with all the metal ions and the differences of chemical shifts were decreased as increasing of the cavity-size of crown ethers for the same metal ions and decreasing of the atomic number of the rare earth metals for the same ligands. It has been found that crownand 22 gave a stable complex with uranium(Ⅵ) ion by the coordination through both oxygen and nitrogen atoms of the ligand whereas no complex was formed with the rare earth metal(Ⅲ) ions, which on the other hand were found to form stable complexes with cryptand 221. The rest of the crowand ligands have also been found to form stable complexes with uranium(Ⅵ) ion by coordinating through all the oxygen and nitrogen atoms of the ligands whereas no complexes were formed with the rare earth metal(Ⅲ) ions. It has also been shown by 1H-NMR study that uranium(Ⅵ), thorium(Ⅳ) and rare earth metal(Ⅲ) ions formed 1:1 complexes with the macrocyclic ligands except for thorium(Ⅳ) complex of 12C4 in which the mole ratio of metal to ligand is 1:2. More stable metal complexes show larger changes in chemical shifts of the coordinated ligand protons. Finally, the rare earth metal(Ⅲ) complexes of 18C6 have shown ligand exchange reaction with the solvent molecules in acetylacetone solution, which was not observed for the uranium (Ⅵ) complexes.

• Proceedings of the Technology Innovation Conference
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• 1998.06a
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• pp.116-127
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• 1998

The Necessity of Cyber University. Within the rapidly changing environment of global economics, the environment of higher education in the universities, also, has been, encountering various changes. Popularization on higher education related to 1lifetime education system, putting emphasis on the productivity of education services and the acquisition of competitiveness through the market of open education, the breakdown of the ivory tower and the Multiversitization of universities, importance of obtaining information in the universities, and cooperation between domestic and oversea universities, industry and educational system must be acquired. Therefore, in order to adequately cope wi th these kinds of rapid changes in the education environment, operating Cyber University by utilizing various information technologies and its fixations such as Internet, E-mail, CD-ROMs, Interact ive Video Networks (Video Conferencing, Video on Demand), TV, Cable etc., which has no time or location limitation, is needed. Using informal ion and telecommunication technologies, especially the Internet is expected to Or ing about many changes in the social, economics and educational area. Among the many changes scholars have predicted, the development and fixations of Distant Learning or Cyber University was the most dominant factor. In the case of U. S. A., Cyber University has already been established and in under operation by the Federate Governments of 13 states. Any other universities (around 500 universities has been opened until1 now), with the help of the government and private citizens have been able to partly operate the Cyber University and is planning on enlarging step-by-step in the future. It could be seen not only as U. S. A. trying to elevate its higher education through their leading information technologies, but also could be seen as their objective in putting efforts on subordinating the culture of the education worldwide. UTRA University in U. S. A., for example, is already exporting its class lectures to China, and Indonesia regions. Influenced by the Cyber University current in the U.S., the Universities in Korea is willing .to arrange various forms of Cyber Universities. In line with this, at JUNAM National University, internet based Cyber University, which has set about its work on July of 1997, is in the state of operating about 100 Cyber Universities. Also, in the case of Hanam University, the Distant Learning classes are at its final stage of being established; this is a link in the rapid speed project of setting an example by the Korean Government. In addition, the department of education has selected 5 universities, including Seoul Cyber Design University for experimentation and is in the stage of strategic operation. Over 100 universities in Korea are speeding up its preparation for operating Cyber University. This form of Distant Learning goes beyond the walls of universities and is in the trend of being diffused in business areas or in various training programs of financial organizations and more. Here, in the hope that this material would some what be of help to other Universities which are preparing for Cyber University, I would 1ike to introduce some general concepts of the components forming Cyber University and Open Education System which has been established by JUNAM University. System of Cyber University could be seen as a general solution offered by tile computer technologies for the management on the students, Lectures On Demand, real hour based and satellite classes, media product ion lab for the production of the multimedia Contents, electronic library, the Groupware enabling exchange of information between students and professors. Arranging general concepts of components in the aspect of Cyber University and Open Education, it would be expressed in the form of the establishment of Cyber University and the service of Open Education as can be seen in the diagram below.

• The Korean Journal of Pesticide Science
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• v.16 no.3
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• pp.202-208
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• 2012

A high-performance liquid chromatographic (HPLC) method was developed to determine residues of cyromazine, a triazine insecticide, in agricultural commodities. Cyromazine was extracted with 90% aqueous methanol from representative crops which comprised brown rice, oyster mushroom, oriental melon, watermelon, and Chinese cabbage. Following to evaporation of methanol in the extract, the aqueous concentrate was acidified to form the protonated cyromazine. Dichloromethane partition was then applied to remove nonpolar co-extractives in the aqueous phase. Strong cation-exchange chromatography using Dowex 50W-X4 resin was employed for final purification of the extract. Cyromazine was successfully separated on a Zorbax SB-Aq $C_{18}$ column showing high retention for polar compounds. Cyromazine was sensitively quantitated by ultraviolet absorption at 214 nm. Limit of quantitation (LOQ) of the method was 0.04 mg/kg irrespective of sample types. Each crops were fortified at 3 different concentrations of cyromazine for recovery test. Mean recoveries from samples fortified at LOQ~2.0 mg/kg in triplicate ranged 80.2~103.3% in five agricultural commodities. Relative standard deviations in recoveries were all less than 6%. A selected-ion monitoring LC/MS method with electrospray ionization in positive-ion mode was also provided to confirm the suspected residue. The proposed method was reproducible and sensitive enough to routinely determine and inspect the residue of cyromazine in agricultural commodities.