• Journal of Korean Society of Water and Wastewater
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• v.23 no.3
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• pp.353-362
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• 2009

A new method and equipment for measuring the zeta potential of the external surface of hollow fiber (HF) membranes is reported. An existing commercial streaming potential analyzer in conjunction with home-made test cells was used to determine the electrokinetic surface characteristics of various HF membranes. It was shown that measurements of the external surface of HF membrane using the home-made test cells designed in this study were easy and reliable. The zeta potential values were quite accurate and reproducible. By varying the physical shape of the test cells to adjust hydrodynamics inside the test cells, several upgrade versions of home-made test cells were obtained. It was shown that the zeta potential of the external surface of HF membranes was most influenced by membrane materials as well as the way of surface modification. However, the overall surface charge of tested HF membranes were much less than that of commercial polyamide thin-film-composite (TFC) reverse osmosis (RO) membranes due to the lack of surface functional groups. For the HF membranes with the same material, the effect of pore size on the zeta potential was not significant, implying the potential of accurate zeta potential measurements for various HF membranes. The results obtained in this study are expected to be useful for better understating of electrokinetic surface characteristics of the external surface of HF membranes.

• Journal of the Korean Mathematical Society
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• v.33 no.1
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• pp.89-99
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• 1996

• Journal of Forest and Environmental Science
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• v.29 no.1
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• pp.99-108
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• 2013

This study was conducted to evaluate the non-timber forest functions of the Research Forest area of Kangwon National University. In this study, forest recreation function was investigated through survey method answered by forest management experts. The evaluation factors for forest recreation function were separated into external and internal factors. Each factor was classified into intermediate element and detailed element. Therefore in this study, the evaluation factors of forest recreation function were divided into two groups which are the potential of external factors and the suitability of internal factors. Potential of the external factors were divided into accessibility, location, landscape and induction factors while the suitability of internal factor was divided into stand structure, forest structure and human impact. The priority of the potential of external factors was in order that location, accessibility, induction factors and landscape. The most important factors for the location, accessibility, induction and landscape factors are based on regional characteristics.

• Journal of Environmental Science International
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• v.21 no.3
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• pp.383-390
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• 2012

For the cost-effective biological nitrogen removal (BNR) process whose characteristics of influent have low COD/N ratios, the automatic control system for the addition of external carbon based on oxidation-reduction potential (ORP) data in an anoxic reactor has been developed. In this study, it was carried out with a pilot-scale Bardenpho process which was consisted of anoxic 1, aerobic 1, aerobic 2, anoxic 2, aerobic 3 tank and clarifier. Firstly, the correlation coefficient ($R^2$) of the dosage of external carbon source and ORP value was about 0.97. Consequently, the automatic control system using ORP showed that the dosage of external carbon source was decreased by about 20% compared with a stable dosage of 75 mg/L based on the COD/N ratio of the anoxic influent.

• The Journal of the Korea Contents Association
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• v.11 no.10
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• pp.217-233
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• 2011

In this study, we have examined how the potential users of IT convergence product use the external information sources for purchasing decision focusing on a case of smartphone. Although the specifications and price of IT convergence products, such as smartphone, tablet pc, and smart TV, are considered as major criteria for purchasing decision, the competitiveness of these factors have disappeared as many companies launch similar products in the market. External information sources play a significant role to differentiate the alternatives by offering value-added experience information. The effect of external information sources becomes stronger for experience and high-involvement product whose performance can be evaluated through only users' direct experience. In this study, we categorized the external information sources for smartphone into five; company ads, personal network, expert group, consumers, and media. Through an empirical study with potential smartphone users, we verified how these external information sources affect users' purchasing decision in the perspective of the perceived attributes of information source, quality of information, and individual's characteristics based on self-regulatory theory.

• The Korean Journal of Physiology
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• v.13 no.1_2
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• pp.41-50
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• 1979

The activation mechanism of K-induced contracture was studied in renal vascular muscle which does not generate an action potential readily and in taenia coli which generates a spike potential spontaneously. Helical strips of arterial muscle from rabbit renal arteries and longitudinal strips of taenia coli from guinea-pig's colons, respectively, were prepared. All experiments were performed in Tris-buffered Tyrode solution which was aerated with 100% $O_2$ and kept $35^{\circ}C$. Renal arterial muscles developed the contracture rapidly, which was composed of a small phasic and a large tonic components, when exposed to a 40 mM K-Tyrode solution. In the absence of external $Ca^{++}$, however, no K-contracture appeared. The contracture induced by K-depolarization was abolished by the treatment with verapamil, which is known to be a selective $Ca^{++}-blocker$ through potential-sensitive $Ca^{++}-channel$. K-contracture of taenia coli showed the contracture composed of a large phasic and a small tonic components. In the $Ca^{++}-free$ Tyrode solution, only the tonic component was abolished and almost no change in the phasic component was observed. The amplitude of tonic component was dependent on the external $Ca^{++}$; The tonic component increased dose-dependently by a stepwise increase of the external $Ca^{++}$, and this component decreased in parallel with the increase of verapamil in the external medium. The results of this experiment suggest that K-contracture of rabbit renal artery is the direct result of the influx of the external $Ca^{++}$, while that of taenia coli is the result of both $Ca^{++}$ influx and the release of sequestered $Ca^{++}$.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.719-728
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• 2015

Following the Fukushima accident, a special safety inspection was conducted in Korea. The inspection results show that Korean nuclear power plants have no imminent risk for expected maximum potential earthquake or coastal flooding. However long- and short-term safety improvements do need to be implemented. One of the measures to increase the mitigation capability during a prolonged station blackout (SBO) accident is installing injection flow paths to provide emergency cooling water of external sources using fire engines to the steam generators or reactor cooling systems. This paper illustrates an evaluation of the effectiveness of external cooling water injection strategies using fire trucks during a potential extended SBO accident in a 1,000 MWe pressurized water reactor. With regard to the effectiveness of external cooling water injection strategies using fire engines, the strategies are judged to be very feasible for a long-term SBO, but are not likely to be effective for a short-term SBO.

• Progress in Superconductivity and Cryogenics
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• v.16 no.1
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• pp.1-5
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• 2014

We calculated the resonance tunneling energy band in the BCS gap for Type-II superconductor in which periodic potential is generated by external magnetic flux. In this model, penetrating magnetic flux was assumed to be in a fixed lattice state which is not moving by an external force. We observed the existence of two subbands when we used the same parameters as for the $Nd_{1.85}Ce_{0.15}CuO_X$ thin film experiment. The voltages at which the regions of negative differential resistivity (NDR) started after the resonant tunneling ended were in a good agreement with the experimental data in the field region of 1 T - 2.2 T, but not in the high field regions. Discrepancy occurred in the high field region is considered to be caused by that the potential barrier could not be maintained because the current induced by resonant tunneling exceeds the superconducting critical current. In order to have better agreement in the low field region, more concrete designing of the potential rather than a simple square well used in the calculation might be needed. Based on this result, we can predict an occurrence of the electromagnetic radiation of as much difference of energy caused by the 2nd order resonant tunneling in which electrons transit from the 2nd band to the 1st band in the potential wells.

• East Asian Journal of Business Economics (EAJBE)
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• v.7 no.4
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• pp.1-13
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• 2019

Purpose - Based on transaction cost perspective and institution-based perspective, this research attempts to investigate the effect of outsourcing on a firm's performance and how it interacts with institutional context in which the firms operate. Research design, data, and methodology -With a sample of 164 manufacturing firms form South Korea, we examine the direct effects of outsourcing on the a firm's level of product innovation and internationalization and the moderating effects of competitive pressure and property right protection as important external factors that could affect the effectiveness of outsourcing decision. Result - The findings show that outsourcing not only enhance a firm's capability to concentrate on its core competencies, but also to increase a firm's combinative capacity to acquire external knowledge. Furthermore, we finds that in a highly competitive environment, potential knowledge spillovers to other competitors may attenuate the potential benefits of outsourcing. Conclusion - Outsourcing can enhance a firm's innovation activities by providing valuable access to external knowledge and also to complementary resources from the external partners, which in turn enables firms to focus on core competences.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.699-708
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• 2023

Nuclear power plants (NPPs) consider possible external events, including natural hazards, during the design phase to ensure safe operation. However, in recent years, due to the increasing probability of natural hazards exceeding the design, a careful review of extreme natural hazards and unforeseen external events during the design phase has become necessary. In this study, the objective was to screen potential extreme natural hazards at NPP sites in Korea. Initially, we investigated and analyzed the characteristics of NPP sites and the events caused by external hazards. Furthermore, we analyzed existing literature and research data to establish screening procedures and criteria that suit the actual conditions of domestic NPPs. Based on these criteria and data, we conducted qualitative screening for each NPP site and identified potential extreme natural hazards through quantitative screening and walkdown. As a result of the screening, in addition to internal flooding caused by heavy rain, wind pressure and extreme air pressure caused by extreme winds were screened as potential extreme natural hazards common to all sites. Additionally, at the Kori site, storm surge was selected as the most significant potential extreme natural hazard.