• Bulletin of the Korean Mathematical Society
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• v.48 no.3
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• pp.455-468
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• 2011

We introduce the notion of refinement rings, and generalize some comparability properties of regular rings to the setting of refinement rings.

• The Journal of Fisheries Business Administration
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• v.40 no.1
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• pp.27-49
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• 2009

Recently, the Korea's economy concerns the second money crisis because of the rapid increase of the exchange rate. The Korea's economy which is very dependent on the foreign trade is more sensitive to the change of exchange rates. There are many literatures which analyze the effects of variations of the exchange rates on the secondary and tertiary industries such as the manufacturing industry and IT(Information Technology). But there have been no studies which try to figure out the effects of variations of exchange rate on the primary industries, especially, fisheries' industry. Therefore this paper tries to analyze the effect of price competition structure and the change of exchange rate on foreign fisheries exporting prices in Korea's fisheries import market. This study utilizes OLS(Ordinary Least Squares Analysis) for the analysis in the market of frozen yellow corvina, hairtail, angler fish which are major fisheries importable in Korea. The results show that the exporting country which has the highest market share is more sensitive to the change of the exchange rates itself than that of the other exporting countries' price when it starts to set up its exporting price. And the exporting countries which have low market share are more sensitive to the change of price which country has the highest market share than that of price whose countries have low market share and those of their exchange rate. Also we can find out that the countries which have similar market share try to set up price-setting strategy in the opposite direction. In other words, one country tries to bid up its price, other countries response to rival country by lowering their prices. In the consideration of the fact that most exporting countries aren't affected by Korea's fisheries' prices, the exporting countries in Korea's fisheries import market are more sensitive to the prices of other exporting countries than that of Korea's. This result indicates that the price leader-follower model could be applicable to the Korea's fisheries import market.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.361-369
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• 2018

A manufacturing method has been devised to prepare novel heterogeneous cation exchange membranes by mixing ethylene vinyl acetate (EVA) copolymers with a commercial cation exchange resin. Optimum material characteristics, mixture ratios and manufacturing conditions have been worked out for achieving favorable membrane performance. Ion exchange capacity, electrical resistance, water uptake, swelling ratio and tensile strength properties were measured. SEM analysis was used to monitor morphology. Effects of vinyl acetate (VA) content, melt index (MI) and ion exchange resin content on properties of heterogeneous cation exchange membranes have been discussed. An application test was carried out by mounting a selected membrane in a membrane capacitive deionization (MCDI) system to investigate its desalination capability. 0.92 meq/g of ion exchange capacity, $8.7{\Omega}.cm^2$ of electrical resistance, $40kgf/cm^2$ of tensile strength, 19% of swelling ratio, 42% of water uptake, and 56.4% salt removal rate were achieved at best. VA content plays a leading role on the extent of physical properties and performance; however, MI is important for having uniform distribution of resin grains and achieving better ionic conductivity. Overall, manufacturing cost has been suppressed to 5-10% of that of homogeneous ion exchange membranes.

• KDI Journal of Economic Policy
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• v.31 no.2
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• pp.235-266
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• 2009

This paper investigates changes in the extent of exchange rate pass-through to export price in Korea. First, empirical results show that export prices have become less responsive to the exchange rate since the financial crisis in 1997. The decline of exchange rate pass-through to export prices suggests that Korean exporters are more likely to use profit margins to absorb part of the impact of exchange rate changes, consistent with pricing to market phenomenon. Second, this paper finds asymmetries in the response of export prices to exchange rate changes. In the post-crisis period. appreciations are more likely to be offset by markup adjustment than depreciations. Third, this paper documents that a significant portion of the decline of exchange rate pass-through is a result of both increased volatility of exchange rate and increased competition with China in the world market.

• Journal of the Korean Magnetics Society
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• v.12 no.4
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• pp.143-148
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• 2002

We report an experimental evidence of coexistence of the strong and weak exchange couplings in unidirectional NiO/NiFe (antiferromagneticlferromagnetic) bilayer thin films. The exchange bias was measured by VSM and AMR techniques and then, analyzed into the strong and weak exchange couplings by means of a regression method. In NiO(60nm)/NiFe(10nm) film, the ratio of the weak exchange coupling field over the average exchange coupling field was found to be almost unchanged within it range from 0.2 to 0.4 irrespective to the strength of an applied field. However, the ratio increased among the samples with decreasing the average exchange coupling field due to the increment of the weak exchange coupling area.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.3
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• pp.206-215
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• 2010

The multi-outlets were installed on the existing seawater exchange breakwater in order to improve seawater exchange rate at Jumunjin harbor. Physical and numerical model system were fulfilled for 4 cases to evaluate seawater exchange system which is able to discharge water remotely. The seawater circulation pattern and seawater exchange rate in the harbor were compared and analyzed. Consequently, total seawater exchange rate for CASE 1 was calculated 48% due to the dead zones which hinder seawater circulation in the harbor. Otherwise, the seawater exchange rates of CASE 2, CASE 3, and CASE 4 with the installation of the system were enhanced 19%, 15% and 17%, respectively compare to CASE 1.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.1043-1051
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• 2009

This study intends to discuss the influence on behaviors of won/dollar exchange rate after a FTA between Korea and US come into effect. The change of behaviors of won/dollar exchange rate has been looked into concerning other countries who have signed a FTA pact with the US, and these examples were compared with that of Korea so as to find similarities and differences. As a result of analyses, behaviors of exchange rate between FTA-pact countries were showed differently. Volatility and risk premium somewhat decreased after the FTA took effect except for Chile. As for Chile, showing intense volatility, foreign exchange risk premium rather increased. It can be concluded that the relationship between volatility and risk premium of individual exchange rate is established and FTA can influence change of these behaviors of exchange rate depending on the situation of individual country. This study will contribute to offer informations to Korea trading companies related to IT that will have to prepare for the uncertainties of change of exchange rate due to FTA between Korea and US.

• Polymer(Korea)
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• v.31 no.3
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• pp.239-246
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• 2007

The sulfonated ion exchange fibers were synthesized by $Co^{60}\;{\gamma}-ray$ radiation-induced graft copolymerization. Degree of grafting was increased with increasing the total dose. The degree of grafting for POF-g-St/DVB copolymer was 1000%. The ion exchange capacity of sulfonated ion exchange fibers were increased by increasing the degree of sulfonation. Its maximum value was 5.06 meq/g. The ion exchange capacity of sulfonated POF- co-St/DVB ion exchange fiber was higher than that of the sulfonated POF- co-styrene ion exchange fibers. The amount of adsorption for heavy metals were also increased with increase in the degree of grafting of the ion exchange fibers.

• Membrane Journal
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• v.30 no.1
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• pp.21-29
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• 2020

In this study, we have established the optimum design condition of pore-filled anion-exchange membrane for all-vanadium redox flow battery (VRFB). From the experimental results, it was proven that the membrane design factors that have the greatest influence on the charge-discharge performance of VRFB are the ion exchange capacity, the porosity of substrate film, and the crosslinking degree. That is, the ohmic loss and the crossover of active materials in VRFB were shown to be determined by the above factors. In addition, two methods, i.e. reducing the ion exchange capacity at low crosslinking degree and increasing the crosslinking degree at high ion exchange capacity, were investigated in the preparation of pore-filled anion-exchange membranes. As a result, it was found that optimizing the crosslinking degree at sufficiently high ion exchange capacity is more desirable to achieving high VRFB charge-discharge performances.

• The Korean Journal of Ecology
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• v.3 no.1_2
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• pp.1-10
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• 1980

This study was carried out to find out the correlation between plant groups and environomental gradient in the native grassfild near Kang Nam Express Terminal from August 26 to september 15, 1977. The correlations among plant species were calculated by using the method of x2 and the various relationships among soil environmental gradients were grouped by means of correlation coefficient. As a result, both the species and the soil environmental factors could be subdivided into four groups, and the four groups of the native grassfield were turned out to be correlated with the four groups of soil environmental factors. The first plant group (Panicum dichotomiflorum, Chenopodium album, Bidens forndosa, Humulus japonicus, Alopeculus amurensis, Potentilla fragarioides, Centipeda minima, Beckmannia erucaeformis) was formed in the releve 1∼10 reagions, organic matter by Turins's method, Total N, Exchange Ca and total of Exchange K, Na, Kg, Ca were abundent. The second plant group (Digitaria sanguinalis, Paltulaca oleracea, Echinochlea macrocrovi, Cyperus amuricus) was formed in the relve 11∼18 reagions, where Exchange Ca and total of Exchange K, Ng, Mg, Ca were little but Exchange A1 and sand were aburdent. In relve 19∼20 reagions, with much of Exchange Ca, total of Exchange K, Na, Mg, Ca, pH and a little Exchange Al, was found the third plant group (Pycreus sanguinoloentus, Cyperus amuricus, Ludwigia prostrata, Echinochloa echinata, Polygonum thunbergii, Salix glandulosa seedling) The fourth plant group (Cassia nomame, Polygnoum perfoliatum, Setaria viridis, Glocien ussuriensis, Lactuca indica, setaria glauca, Artemisia capill aris, Artmisia asiatica, Calamagrostis arundinacea, Kummerowia striata, Denothera odorata, Artemisia japonica, Carey laceolata) was formed in relve 21∼25 reagions, where organic matter by loss on ignition, Exchange Mg and Maximum water holding capacity were abundent but sand was a little. Thus it can be concluded that there is a close relationship between the vegetation group clasified by meaus of x2 and the environtal factors of soil devided by means of correlations coefficient.