• Membrane Journal
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• v.15 no.3
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• pp.198-205
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• 2005

Double-layered polymer films to assay the radioactive contamination were formulated using polysulfone (PSF) and cerium activated yttrium silicate (CAYS), consisting of a dense support layer and a CAYS-holding top layer prepared via the diffusion-induced phase inversion. As the vapor exposure process was omitted, the CAYS-holding layer showed a typical asymmetric structure, with CAYS being transfixed into the polymer network spread with large macropores. With the increase in vapor exposure time before immersion, morphology of the films transformed from asymmetric to sponge-like structures, with CAYS being localized in cellular structure. The border structure between the two layers reflects the phase inversion behavior of a cast solution during the coagulation. In the radioactive detection, the polymer phase in a film holding a sponge-like structure is so dense that the radionuclides, deposited on the film, could not filter through the phase, consequently resulting in the loss in the detection efficiency of the film.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.685-692
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• 1998

Since a wet-seal area of Molten Carbonate Fuel Cell (MCFC) operated at $650^{\circ}C$ is exposed to severe environment, a life-time of MCFC is influenced by the corrosion resistance of separator. In order to improve corrosion resistance of 316L stainless steel used as separator material, AI- base alloy such as NiAI has been widely used as coat¬ing material on the wet-seal area. The purpose of this work is to develope a more protective coating material by adding yttrium on NiAI alloy. An immersion test and a polarization test were performed in molten carbonate salt at $650^{\circ}C$ to estimate corrosion resistance of the NiAI alloy and the NiAl/Y alloys with up to L5at% yttrium. NiAl/Y alloys showed better corrosion resistance than NiAI alloy. We found that more than 0.7 at% yttrium was required to improve the corrosion resistance of NiAI alloy in molten carbonate salt at $650^{\circ}C$.

• Nuclear Engineering and Technology
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• v.43 no.6
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• pp.557-566
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• 2011

A cold spray coating (CSC) of copper was studied for its application to a high-level radioactive waste (HLW) disposal canister. Several copper coatings of 10 mm thick were fabricated using two kinds of copper powders with different oxygen contents, and SS 304 and nodular cast iron were used as their base metal substrates. The fabricated CSC coppers showed a high tensile strength but were brittle in comparison with conventional non-coating copper, hereinafter defined to as "commercial copper". The corrosion behavior of CSC coppers was evaluated by comparison with commercial coppers, such as extruded and forged coppers. The polarization test results showed that the corrosion potential of the CSC coppers was closely related to its purity; low-purity (i.e., high oxygen content) copper exhibited a lower corrosion potential, and high-purity copper exhibited a relatively high corrosion potential. The corrosion rate converted from the measured corrosion current was not, however, dependent on its purity: CSC copper showed a little higher rate than that of commercial copper. Immersion tests in aqueous HCl solution showed that CSC coppers were more susceptible to corrosion, i.e., they had a higher corrosion rate. However, the difference was not significant between commercial copper and high-purity CSC copper. The decrease of corrosion was observed in a humid air test presumably due to the formation of a protective passive film. In conclusion, the results of this study indicate that CSC application of copper could be a useful option for fabricating a copper HLW disposal canister.

• Membrane Journal
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• v.11 no.4
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• pp.170-178
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• 2001

PVC microfiltration membrane was prepared by phase immersion method and applied to membrane bioreactor (MBR) contained activated sludge. The hydrophilicity of membrane and the pore size increase with the amount of additive(PVP) ducting the preparation of membrane. Permeation characteristics and the membrane fouling behavior were investigated by varying the internal environment in MBR using the prepared membranes. When there is a sludge bulking in MBR caused by microorganism, membrane fouling was accumulated. The cake layer resistance, R$_{c}$, of membrane increased in the order of CP-0 > CP-1.0 > CP-1.5. Rc increased up to 3.5~7 fold where the sludge bulking occurred in MBR. CP-1.5 seems to be appropriated membrane on the basis of the surface characteristics and the flux. The average flux of all the test membrane was 12(${\pm}$2) L/$m^2$hr whereas the COD removal efficiency was 98.8%. The ratio of bulking sludge and the type and the size of microorganism in operating MBR accelerate the membrane fouling and flux decline. It is concluded that the characteristic of membrane filtration depends on the hydrophilicity of membrane, the internal environment of MBR reactor and the growth factor of sludge.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.1
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• pp.40-48
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• 2021

Through a series of bollard pull tests of a propeller in partially submerged condition, thrust, torque, and shaft excitation force of a conventional propeller model were measured using a six-component load cell. By variation of the Weber number and Reynolds number, a consistent towing tank model test condition was derived. The effects of propeller immersion depth on the ventilation behavior and change of force and moment acting onto the propeller shaft were investigated. The decrease in thrust owing to the inception of ventilation was confirmed, and a large degree of dispersion of the thrust and torque coefficients were also observed in the transition region where the blade tip was under the water surface. The shaft excitation force was derived from the force and moment onto the propeller shaft.

• Journal of the Korean institute of surface engineering
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• v.55 no.2
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• pp.102-119
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• 2022

Gold plating is used as a coating of connecter in printed circuit boards, ceramic integrated circuit packages, semiconductor devices and so on, because the film has excellent electric conductivity, solderability and chemical properties such as durability to acid and other chemicals. As increasing the demand for miniaturization of printed circuit boards and downsizing of electronic devices, several types of electroless gold plating solutions have been developed. Most of these conventional gold plating solutions contain cyanide compounds as a complexing agent. The gold film obtained from such baths usually satisfies the requirements for electronic parts mentioned above. However, cyanide bath is highly toxic and it always has some possibility to cause serious problems in working environment or other administrative aspects. The object of this investigation was to develop a cyanide-free electroless gold plating process that assures the high stability of the solution and gives the excellent solderability of the deposited film. The investigation reported herein is intended to establish plating bath composition and plating conditions for electroless gold plating, with thiomalic acid as a complexing agent. At the same time, we have investigated the solution stability against nickel ion and pull strength of solder ball. Furthermore, by examining the characteristics of the plated Au plating film, the problems of the newly developed electroless Au plating solution were improved and the applicability to various industrial fields was examined. New type electroless gold-plating bath which containing thiomalic acid as a complexing agent showing so good solution stability and film properties as cyanide bath. And this bath shows the excellent stability even if the dissolved nickel ion was added from under coated nickel film, which can be used at the neutral pH range.

• The Journal of the Korea Contents Association
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• v.21 no.7
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• pp.171-180
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• 2021

Places exposed to mass media induce behavior by forming curiosity and expectations for potential travelers. The places reported through mass media influence viewers. Among TV programs, the most influential genre is drama, and reality programs that provide immersion with different characteristics from dramas influence viewers' choice of destination. CVM is mainly used for estimating the value of objects that cannot be evaluated in the market, such as tourist destinations. This study conducted an economic valuation of filming locations for dramas and travel entertainment programs using CVM, and then compared and analyzed the research results of the two filming locations. Linear and log logit analysis were performed to measure the willingness to pay for the filming location of the drama/travel entertainment program, and the payment amount was derived. The conclusion of the study is that as the travel cost required to visit the filming location of the drama/travel entertainment program increased, the intention to visit decreased. The amount payable when visiting the filming location of the drama/travel entertainment program was higher than the average consumption amount for a day trip, and the amount payable for the drama was higher than that of visiting the filming location of the travel entertainment program.

• Composite Materials and Engineering
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• v.3 no.3
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• pp.167-178
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• 2021

In the present paper, the destructive behavior of distilled water, salty water, sulfuric acid, and heat on glass/vinyl ester composites was investigated by experimental methods. Hetron 922 vinyl ester resin and two types of mat and woven glass fibers as the reinforcements were used to fabricate composite test samples. All samples were immersed in distilled water, salty water, and sulfuric acid with three different concentrations. The tests were performed at 20℃ and 70℃ for the exposure duration of 1, 2, 4, and 8 weeks. Bending tests were performed after aging for all composite samples to check the degradation of the bending modulus and strength. The results show that the effect of distilled water, in comparison with salty water, on the degradation of composite samples was significant. On the other hand, almost non-sensitivity of concentrations of salty water on the weight gain of specimens has been observed. In addition, it was also observed that the degradation of samples at 70℃ temperature is much more than that of at 20℃. Also, it was observed that the flexural modulus of virgin specimens exposed to salty water (2% concentration) has been recovered just after two weeks of immersion. Furthermore, in some cases, composite samples under the sulfuric acid solution have lost almost 80% of their mechanical properties.

• Journal of Wellness
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• v.7 no.2
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• pp.113-121
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• 2012

This study chose the academic journals related with e-sports for analysis among the top tier journals of National Research Foundation of Korea from 2006 to 2011 to check the academic trend Beginning in 2006, the first study of e-sports was published in the journal related with e-sports. So, the studies from 2006 to 2011 were chosen for analysis. Using Research Information Sharing Service(RISS), the keyword 'e-sports' was searched. By virtue of this process, total 27 studies were selected as final analysis. So, the academic trends are as follows. In Korea, the studies related with e-sports have started from the beginning of 2000s with internet and then it spread out via cable TV. And then from the middle of 2000s, e-sports was discussed seriously. The early subject of the studies usually focused on the measurement of e-sports based on the strategic elements as a product. After that, game addiction and violent tendency which were one of the biggest issues were raised as a constant problem and it became the academic studies of user behavior. E-sports became a recreation culture of teenagers so it has been in charge of the role of exit and the problems related with it have continuously appeared. So, the academic studies tend to have departmentalization like immersion, addiction, sociality, self-regulation and etc. But, there was a tendency that the similar contents were repeated in the view point of subject and method while the subjects were departmentalized. So, for the systematic study of e-sports, development of the unique subject, study method and verification process should be conducted continuously.

• Korean Journal of Childcare and Education
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• v.11 no.6
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• pp.133-151
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• 2015

The aim of this study was to examine how children's self control, mother's addiction to smart devices and parenting behavior influence the way young children used smart devices. Participants were made up of 166 preschoolers and their mothers. Descriptive analysis, Pearson's correlation coefficient, and hierarchical regression analysis were used for statistical analysis. The results were as follows: First, children in their early childhood years used smart devices once or twice a week, for ten to thirty minutes, mainly during weekends. Children in their early childhood stage started to use smart devices before reaching the age of 3, and accessed them through their parents, usually along with their siblings. Parents allowed their children to use smart devices for fun and entertainment, with only 66.3% of them setting rules. Second, the mother's tendency to be immersed in smart devices, overprotection and permission were positively correlated to young children's overusage of smart devices, whereas geniality, encouragement, setting limits, and children's self control were negatively correlated. The study also found that the mother's tendency of being immersed in smart devices was the most influential factor for their children's overusage of smart devices. The value of this study lies in providing practical suggestions for children's smart device usage and parental education programs.