• Economic and Environmental Geology
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• v.32 no.1
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• pp.53-62
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• 1999

The possibility of heavy metal pollution by contaminated roadside soils was studied under controlled conditions. The soil samples from roadside and those from a retention pond consisting of settling particles were characterized by the XRD analyses and the sequential extraction experiments. Characterization by sequential extraction, for roadside soil indicates elevate total concentrations of heavy metals. The leaching behavior of the samples under different pH and time conditions were also studied. Differences between both types of samples result mainly from the buffering effect of carbonates, present in roadside soils and lacking from settling particles. Acid leaching of the settling particles is equivalent to the sum of FI+FII+FIII, while the amounts leached from roadside soil are lower probably from kinetic reasons. The buffering effects of carbonates were found to greatly delay the onset of the leaching reactions and the extent of dissolution in most metals except for Ca and Mn. The study of leaching kinetics at pH of 6.5 and 5 showed that Cd and Zn reached the maximum possible concentration within 3 days, while Pb did not show any sign of dissolution at both ph values. The absolute amounts of dissolved Cd and Zn increased by 7 to 9 times by decreasing the pH from 6.5 to 5, indicating slightly acidified rain may result in significant metal dissolution. As deduced from both sequential extraction and leaching experiments, the relative mobility of heavy metals is found to be : Mn=Cd>Zn>>Pb>Fe, in spite of large differences in heavy metal contents and localizations.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.915-924
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• 2016

After a severe accident to the nuclear reactor, the in-vessel retention strategy is a key way to prevent the leakage of radioactive material. Nanofluid is a steady suspension used to improve heat-transfer characteristics of working fluids, formed by adding solid particles with diameters below 100nm to the base fluids, and its thermal physical properties and heat-transfer characteristics are much different from the conventional working fluids. Thus, nanofluids with appropriate nanoparticle type and volume concentration can enhance the heat-transfer process. In this study, the moving particle semi-implicit method-meshless advection using flow-directional local grid method is used to simulate the bubble growth, departure, and sliding on the downward-facing heating surface in pure water and nanofluid (1.0 vol.% $Al_2O_3/H_2O$) flow boiling processes; additionally, the bubble critical departure angle and sliding characteristics and their influence are also investigated. The results indicate that the bubble in nanofluid departs from the heating surface more easily and the critical departure inclined angle of nanofluid is greater than that of pure water. In addition, the influence of nanofluid on bubble sliding is not significant compared with pure water.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.131-138
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• 2007

A rainwater utilization facility consists of its catchment area, treatment facility, storage tank, supply facility and pipes in general. The rainwater storage tank which occupies the largest area of the facility has been usually considered quantitatively for determining the storage capacity. Hence, there is little information on water quality improvement by sedimentation in a rainwater storage tank in operation. In this study, we measured the rainwater quality in a rainwater storage tank in operation during late spring and summer, and showed water quality improvement of turbidity removal of 25~46% by sedimentation in a rainwater storage tank under a fixed water level without inflow and outflow after runoff ceased. It is necessary to have a considerable distance between the inlet and outlet of the tank and, if possible, it is recommended that the design should allow for an effective water depth of over 3 m and supply rainwater near the water surface. The operation method which increases the retention time by stopping rainwater supply for insuring low turbidity is recommended when the turbidity of rainwater runoff is high. And also more efficient operation and maintenance of the rainwater utilization facility is expected through the tailored design and operation of the facility considering particle removal and behavior.

• Korean Chemical Engineering Research
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• v.56 no.5
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• pp.694-704
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• 2018

Novel $SnO_2$ mixed biochar composite was prepared from banana peel developed as electrode material for supercapacitor using simple chemical co-precipitation method. The physiochemical and morphological properties of activated composite $SnO_2$ mixed biochar were investigated with XRD, FTIR, UV-vis, FESEM and HRTEM. The composite accounts for outstanding electrochemical behavior such as high specific capacitance, significant rate capability and leading to good cycle retention up to 3500 cycles when used as electrode material for supercapacitors. Highly permeable $SnO_2$ mixed biochar derived from banana peel exhibited maximum specific capacitance of $465F\;g^{-1}$ at a scan rate of $10mV\;s^{-1}$ by cyclic voltammetry (CV) and $476Fg^{-1}$ at current density of $0.15Ag^{-1}$ by charge discharge studies significantly higher about 47% than previously reported identical work on banana peel biochar.

• The Korean Journal of Community Living Science
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• v.22 no.2
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• pp.283-298
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• 2011

Gender is frequently being identified as a key moderator in consumer behavior studies. However, there has been insufficient studies in this field in rural tourism areas. The purpose of this study examined the structural relationships among rural tourism motivation, satisfaction, and loyalty including the moderating effect of gender. Data were collected from 442 farmstay visitors by field survey in rural areas. SPSS 15.0 and LISREL 8.80 statistical package were used to analyze the data. Principle component analysis and path analysis were carried out to identify the structural relationships. Results showed that refreshment and family togetherness of tourism motivation had a negative effect on satisfaction. However, rural life of tourism motivation had a positive effect on satisfaction. Tourists' satisfaction had a positive effect on loyalty. The results also indicated that gender moderated the relationship among tourism motivation, satisfaction, and loyalty. The study suggested that it was important for tourism service marketers to develop proactive relationship marketing techniques that could have a lasting impact on customer retention.

• The Research Journal of the Costume Culture
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• v.18 no.4
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• pp.655-669
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• 2010

This study focused on examining methods for the favorable relationship between internet shopping mall and customers from a point of view that it was necessary for internet fashion market getting faced with keen competition to change its marketing focus from securing new customers to customer retention strategies. Measurement instruments were selected to measure these variables and a questionnaire was made. Data was collected in 491 men and women in their twenties residing in Gwangju city using the questionnaire. The analysis results were summarized as follows: First, in the failure to purchase fashion products in internet shopping mall, as consumer's favorable internet shopping attributes, their possibility of complaining and repurchase intentions became higher, and had negative effect on regret and dissatisfaction. Second, attributions of the result of a failure to purchase fashion products in internet shopping mall were found to increase regret and dissatisfaction. Third, customers experiencing regret and dissatisfaction showed a very high possibility of complaining but their possibility of repurchase intentions had negative affect.

• Journal of Navigation and Port Research
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• v.36 no.8
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• pp.673-681
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• 2012

As competition increases among ports, new marketing strategies and differentiated means in addition to the existing core services are needed to prevent existing container shipping companies from escaping and to attract new customers. The additional services and reward programs are investigated. How these variables affect relational commitment in terms of customer retention is examined. Customers of the container terminals are examined in terms of psychological behavior. This study presents the structural equation model that shows the connection among benefits, rewards, switching costs and relational commitment. The empirical analysis is done with the subject of the container terminal users and the implications are derived.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.5
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• pp.1-7
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• 2000

Alkaline Sizing behavior and mechanism of handsheets, which were prepared from thermomechanical pulp (TMP) with alkylketene dimer (AKD), were studied in terms of the conditions of the handsheet-making. AKD content in the TMP handsheets was increased with increasing of AKD addition level and the addition of a polyamideamine-epichlorohydrin resin (PAE) clearly enhanced AKD retention as well as the resultant sizing performance of TMP handsheets. Although drying of the AKD sized TMP webs at $20^{\circ}C$ led to no or quite low sizing level, but TMP handsheets sized with AKD had higher sizing degrees with increasing of the temperature of heat treatment. Scanning electron microscopic observations of the AKD-sized TMP handsheets showed that AKD emulsion particles were present on pulp fiber surfaces independently without coagulation in the TMP handsheets dried at $20^{\circ}C$. Heat treatment of the AKD-sized handsheets resulted in disappearance of the AKD emulsion particles because of their melting and spreading. The addition of calcium carbonate filler to the TMP suspensions did not influence on AKD content in the TMP handsheets. Nevertheless, their sizing degrees clearly increased by the addition of $CaCO_3$filler. Probably, AKD molecules adsorbed on the $CaCO_3$filler particles contribute to the enhancement of sizing performance. Thus, AKD can give sizing features effectively to the TMP handsheets, when they are made under suitable conditions.

• The Journal of Korean Physical Therapy
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• v.31 no.1
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• pp.40-48
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• 2019

Purpose: This study assessed the current working conditions and job satisfaction on aquatic therapy performed by physical therapists in South Korea. Methods: A total of 139 (managers: 53, staff: 86) physical therapists participated in this survey (90 questionnaires) and the data were analyzed using the SPSS 21.0 Windows. Results: The retention conditions of aquatic therapy facilitation was high in the rehabilitation centers (or disabled living facilities) and rehabilitation hospitals. On the other hand, there were regional variations. The physical therapists in this field were likely to have limitations or restrictions of professional aquatic therapy education. The subjects showed a tendency for a career interruption during their fifth working year. The overall job satisfaction on aquatic therapy of physical therapists was high (managers: 94.3%, staff: 95.3%, p=0.276), but the work intensity was higher than the other parts of physical therapy and the relative reward was comparatively low (managers: 60.3%, staff: 66.3%, p=0.865). Conclusion: Based on this study, the current working conditions regarding aquatic therapy by physical therapists were assessed. These results will help enhance aquatic therapy and/or in aquatic therapy facilitation.

• Restorative Dentistry and Endodontics
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• v.43 no.4
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• pp.38.1-38.9
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• 2018

The restoration of endodontically treated teeth (ETT) with more than one cusp missing and thin remaining walls is challenging for the general practitioner. The use of posts combined with full coverage restorations is a well-established approach, yet not following the minimal invasive principles of adhesive dentistry. Endocrowns are indirect monoblock restorations that use the pulp chamber of the ETT for retention. In this study the fabrication of 4 endocrowns and their clinical performance will be discussed. Two clinical cases include computer-aided design/computer-aided manufacturing manufactured molar endocrowns (one feldspathic ceramic and one hybrid composite-ceramic restoration) and the other two are dental laboratory manufactured resin composite premolar endocrown restorations. The modified United States Public Health Service criteria were used to assess the clinical behavior of the restorations at different follow up periods. Endocrown restorations present a satisfactory clinical alternative, either by the use of resin composite or glass ceramic and hybrid materials. Specific guidelines with minimal alterations should be followed for an endocrown restoration to be successful. Due to limited evidence regarding the long term evaluation of this restorative technique, a careful selection of cases should be applied.