• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.679-687
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• 2007

Nanoscale zero valent ion (nZVI) technology is emerging as an innovative method to treat contaminated groundwater. The activity of nZVI is very high due to their high specific surface area, and supporting this material can help to preserve its chemical nature by inhibiting oxidation. In this study, nZVI particles were attached to granular ion-exchange resin through borohydride reduction of ferrous ions, and chemical reduction of nitrate by this material was investigated as a potential technology to remove nitrate from groundwater. The pore structure and physical characteristics were measured and the change by the adsorption of nZVI was discussed. Batch tests were conducted to characterize the activity of the supported nZVI and the results indicated that the degradation of nitrate appeared to be a pseudo first-order reaction with the observed reaction rate constant of $0.425h^{-1}$ without pH control. The reduction process continued but at a much lower rate with a rate constant of $0.044h^{-1}$, which is likely limited by mass transfer. To assess the effects of other ions commonly found in groundwater, the same experiments were conducted in simulated groundwater with the same level of nitrate. In simulated groundwater, the rate constant was $0.078h^{-1}$ and it also reduced to $0.0021h^{-1}$ in later phase. The major limitation in application of ZVI for nitrate reduction is ammonium production. By using a support material with ion exchange capacity, the problem of ammonium release can be solved. The ammonium was not detected in the batch test, even when other competitive ions such as calcium and potassium existed.

• Journal of the Korean Chemical Society
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• v.38 no.6
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• pp.442-448
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• 1994

The rate constants of the nucleophilic reaction of ${\alpha}$-(n-butyl)-N-phenylnitrone and its derivatives have been determined by ultraviolet spectrophotometry at $25^{\circ}C$ and a rate equation which can be applied over a wide pH range was obtained. Final product of the addition reaction was $\alpha$-phenylthiobutylidene-aniline. Base on the rate equation, genernal base effect, substituent effect and final product, plausible mechanism of addition reaction have been proposed. Below pH 3.0 the reaction was inititated by the addition of thiophenol, and in the range of pH 3.0∼10.0, proceeded by the competitive addition of thiophenol and thiophenoxide anion. Above the pH 10.0, the reaction proceeded through the addition of a thiophenoxide anion.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.6
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• pp.473-480
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• 2020

High-pressure membrane system like nanofiltration(NF) and reverse osmosis(RO) was investigated as a part of water treatment processes to produce high quality potable water with low organic matter concentration through membrane module tests and design simulation. River water and sand filtration permeate in Busan D water treatment plant were selected as feed water, and NE4040-90 and RE4040-Fen(Toray Chemical Korea) were used as NF and RO membranes, respectively. Total organic carbon(TOC) concentrations of NF and RO permeates were mostly below 0.5 mg/l and the average TOC removal rates of NF and RO membranes were 93.99% and 94.28%, respectively, which means NF used in this study is competitive with RO in terms of organic matter removal ability. Different from ions rejection tendency, the TOC removal rate increases at higher recovery rates, which is because the portion of higher molecular weight materials in the concentrated raw water with increasing recovery rate increases. Discharge of NF/RO concentrates to rivers may not be acceptable because the increased TDS concentration of the concentrates can harm the river eco-system. Thus, the idea of using NF/RO concentrate as the raw water for industrial water production was introduced. The design simulation results with feed water and membranes used in this work reveal that the raw water guideline can be satisfied if the recovery rate of NF/RO system is designed below 80%.

• Convergence Security Journal
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• v.22 no.1
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• pp.141-148
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• 2022

Korea's ROTC system was introduced from the United States in 1961 to recruit competent primary grade officers and secure reserve forces in peacetime. However, entering the 2000s, it was faced with a serious crisis, which was a decrease of the application rate due to the change in the acquisition environment including the decrease in school-age population and military service resources due to the low fertility, and the shortened period of military service. Therefore, this study tried to suggest a ROTC system improvement plan focusing on the organizational structure and operation system by analyzing the change in the acquisition environment and the cause of decrease in the application rate. As a research method, a comparative method between the cases of the ROTC systems in the US and Korea was applied through domestic and foreign literature studies. In terms of theory, Strategic Human Resource Management, which is applied to corporate management to achieve organizational performance and secure comparative competitive advantage in a knowledge-based society, was used as a theoretical criterion.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.151-158
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• 2022

In this paper, parameter characteristics such as pH effect, isotherm, kinetic and thermodynamic parameters and competitive adsorption of dyes including malachite green (MG), direct red 81 (DR 81) and thioflavin S (TS), which have different functional groups, being adsorbed onto activated carbon were investigated. Langmuir, Freundlich and Temkin isotherm models were employed to find the adsorption mechanism. Effectiveness of adsorption treatment of three dyes by activated carbon were confirmed by the Langmuir dimensionless separation factor. The mechanism was found to be a physical adsorption which can be verified through the adsorption heat calculated by Temkin equation. The adsorption kinetics followed the pseudo second order and the rate limiting step was intra-particle diffusion. The positive enthalpy and entropy changes showed an endothermic reaction and increased disorder via adsorption at the S-L interface, respectively. For each dye molecule, negative Gibbs free energy increased with the temperature, which means that the process is spontaneous. In the binary component system, it was found that the same functional groups of the dye could interfere with the mutual adsorption, and different functional groups did not significantly affect the adsorption. In the ternary component system, the adsorption for MG lowered a bit, likely to be disturbed by the other dyes meanwhile DR 81 and TS were to be positively affected by the presence of MG, thus resulting in much higher adsorption.

• Management & Information Systems Review
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• v.12
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• pp.53-75
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• 2003

The Internet is flourishing and the World Wide Web is growing at an exponential rate. A fundamental concept of Intranet, the so-called second wave, was introduced only a few years ago. Intranets have been embraced by corporate users of information services and made substantial inroads in strategic vision documents and procurement practices. Business organizations have come to the conclusion that they require an extensive data repository in order to acquire a competitive advantage in a dynamically change market. This rich assortment of data must further be delivered and deliverable enterprise-wide in a secure and cost-efficient manner. Information technology(IT) has created the Intranet as a vitally important mechanism for the storage, dissemination, and even the analysis data. The present study is an attempt to develop a more through understanding of the potential and actual impact of the Intranet on organizational functions and activities. Expecially, it also consists of an effort to assess the impact of the Intranet on communication. The research also addresses the issue of how the Intranet affects communication and shapes or modifies business activities. The results of literature review and study revealed that middle managers believe that the extent of the Intranet use is significantly related to improvements in overall organizational functions and activities. While communication, decision-making, productivity, work collaboration, and business activities are all enhanced by Intranet use, communication appears to be most dramatically improved by Intranet use.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.822-828
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• 2005

Customer satisfaction becomes one of the important managerial concerns associated with corporate competency in current competitive environment for Internet communication service companies. Hence, it is demanding to improve a company's customer satisfaction through the total quality management perspective. In practice, engineers as well as the management hope to find major quality characteristics with Internet communication network that is closely related to customer satisfaction, consequently aiming to the raise of their company's customer satisfaction. This paper presents an empirical relationship analysis between network quality characteristics and customer satisfaction on Internet communication. Methodologically, the relationship analysis framework is based on the regression variable selection procedures. In this framework, it is implemented that; 1) iterative model building; and 2) consistent criteria application to statistical tests for selecting significant variables. A case study shows that; 1) the customer satisfaction on the network connection seems to be more closely related to the network quality characteristics compared with the customer satisfaction on the network speed; and 2) the download disconnection rate has relatively evident relationship with the customer satisfaction on the network connection.

• Journal of Microbiology and Biotechnology
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• v.15 no.4
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• pp.899-902
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• 2005

Peptide assimilation by Helicobacter pylori was investigated using L-phenylalanyl-3-thia-phenylalanine (PSP) as a detector peptide; the release of thiophenol upon enzymatic hydrolysis of PSP was spectrophotometrically detected with the aid of 5,5'-dithiobis[2-nitrobenzoic acid] (DTNB). By adding PSP to whole-cell suspension, thiophenol was produced progressively, resembling that found in Esherichia coli or Staphylococcus aureus. Interestingly, the rate of thiophenol production by H pylori in particular was markedly reduced when cells were pretreated with trypsin, indicating surface exhibition of peptidase. According to the competitive spectrophotometry using alanyl-peptides, H pylori did not appear to assimilate PSP through the peptide transport system. No discernible PSP assimilation could be ascertained in H pylori cells, unless provided with some additives necessary for peptidase activity, such as $Ni^{2+}\;or\;Mg^{2+}$ and an appropriate concentration of potassium or ammonium salts. These observations strongly suggest that, regardless of a presumptive peptide transport system, peptide assimilation of H. plori appears to be highly dependent upon milieu conditions, due to unique peptidase exhibition on the cell surface.

• The Journal of Information Systems
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• v.13 no.2
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• pp.65-88
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• 2004

This study is intended to identify success factors which influence the performance of the B2B e-marketplaces.Thestudyisfocused on the supply companies and conducted to provide local small businesses with guidelines to improve their competitiveness and to develop appropriate business strategies in the digital economy age. Based on the literature review, four characteristics which influence the performance of B2B e-marketplaces are identified. Such characteristics as strategic, operational, organizational, and product/service properties are then utilized to develop the survey questionaire. The data collection is first performed through e-mail and, after finding out the response rate was too poor to analyze the results, followed by visits to the companies which participate in e-marketplaces. SAS 8.1 is used for the data analysis. Demographic analysis is conducted to generate the general information of the companies responded, and factor analysis is performed for the validity test. Finally, multiple regression is used for the hypothesis testing. This study is expected to contribute to find out critical factors for the success of B2B e-marketplaces and suggest guidelines for local small businesses to develop an appropriate e-business strategy to improve their competitive position.

• International Commerce and Information Review
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• v.7 no.2
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• pp.49-74
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• 2005

E-business has received much attention from entrepreneurs, executives, investors, and industry observers recently. The Internet is flourishing and the World Wide Web is growing at an exponential rate In recent years, information has become the critical commodity needed for success in the changing global economic order. Accordingly, business organizations have come to the conclusion that they require an extensive data repository in order to acquire a competitive advantage in a dynamically change market. This rich assortment of data must further be delivered and deliverable enterprise-wide in a secure and cost-efficient manner. Information technology(IT) has created the E-business as a vitally important mechanism for the storage, dissemination, and even the analysis data. The E-business has become increasingly important to a growing number of organizations in Korea in relatively short order. The present study is an attempt to develop a more through understanding of the potential and actual impact of the E-business on organizational functions and activities. Expecially, it also consists of an effort to assess the impact of the E-business on productivity. The research also addresses the issue of how the E-business affects productivity and shapes or modifies business activities. The results of literature review and study revealed that middle managers believe that the extent of the E-business use is significantly related to improvements in overall organizational functions and activities. While communication, decision-making, productivity, work collaboration, and business activities are all enhanced by E-business use, productivity appears to be most dramatically improved by Intranet use.