• Korean Journal of Materials Research
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• v.29 no.1
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• pp.1-6
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• 2019

Recent industrialization has led to a high demand for the use of fossil fuels. Therefore, the need for producing hydrogen and its utilization is essential for a sustainable society. For an eco-friendly future technology, photoelectrochemical water splitting using solar energy has proven promising amongst many other candidates. With this technique, semiconductors can be used as photocatalysts to generate electrons by light absorption, resulting in the reduction of hydrogen ions. The photocatalysts must be chemically stable, economically inexpensive and be able to utilize a wide range of light. From this perspective, cuprous oxide($Cu_2O$) is a promising p-type semiconductor because of its appropriate band gap. However, a major hindrance to the use of $Cu_2O$ is its instability at the potential in which hydrogen ion is reduced. In this study, gold is used as a bottom electrode during electrodeposition to obtain a preferential growth along the (111) plane of $Cu_2O$ while imperfections of the $Cu_2O$ thin films are removed. This study investigates the photoelectrochemical properties of $Cu_2O$. However, severe photo-induced corrosion impedes the use of $Cu_2O$ as a photoelectrode. Two candidates, $TiO_2$ and $SnO_2$, are selected for the passivation layer on $Cu_2O$ by by considering the Pourbaix-diagram. $TiO_2$ and $SnO_2$ passivation layers are deposited by atomic layer deposition(ALD) and a sputtering process, respectively. The investigation of the photoelectrochemical properties confirmed that $SnO_2$ is a good passivation layer for $Cu_2O$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.10
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• pp.98-104
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• 2020

Recently, friction stir welding of dissimilar materials has become one of the biggest issues in lightweight and eco-friendly bonding technology. In this study, a lightweight torsion beam axle, which is an automobile chassis component, was used in the welding to cast aluminum material. The friction stir welding process of A357 cast aluminum and FB590 high-strength steel as well as the effects of the process parameters were investigated and optimized using a novel definitive screening design (DSD). ANOVA was used to predict the importance of the process parameters with 13 degradation experiments using the proposed DSD. Also, FSWed experiments were conducted using an optical microscope analysis to investigate the tensile strength behavior in the weld area. In addition to determining the interaction between the tool's rotational speed and the plunge speed, results indicate that the influence of the plunge depth was the most significant.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.3
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• pp.889-899
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• 2017

Various efforts and technical development for integrating the ICT technologies to the area of special needs education have been continuing. In this paper we have studied and implemented various ICT-based disability evaluation websites and mobile applications for special needs education and also verified their usefulness from the field test at disability schools. The valuer can access the websites and mobile applications for autistic behavior or learning disability evaluation at the any places and by any devices such as laptop, PC, smartphone and tablet PC. And all the evalation results are stored into and managed at the server database and shared with websites and mobile applications to integrate together easily. From the study about disability evaluation and implementation results we have a confidence that they will be useful to support the seamless evaluation and the continuous monitoring services for the disabled at the special needs education fields.

• Journal of Information Technology Applications and Management
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• v.29 no.6
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• pp.43-62
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• 2022

As the used trading market grows centered on online platforms, it is evolving from practical consumption to pursuing various forms of consumption value. Consumers purchase rare products, enjoy the transaction itself with consumers with the same preference, and investment or eco-friendly value consumption is also increasing. In this regard, the transaction of the second-hand transaction app service must have sincerity in order to respond to various consumption values. In addition, it is necessary to study what components the second-hand trading app service should aim for to secure authenticity and how the usefulness and ease of second-hand trading apps affect the relationship. The research used a questionnaire method to test hypotheses and surveyed 215 consumers in their 20s, 30s, and 40s who had purchased used clothing online within a year. Among them, 200 responses, excluding outliers, were statistically analyzed using SPSS 21.0 and AMOS 22.0 as confirmatory factor analysis and structural equation models. This study aims to determine the effect of the authenticity of the online used trading app service on the satisfaction of the used trading app service. To this end, based on the previous research results, the following research hypotheses were established and verified statistically. First, the authenticity of the online used trading app service will significantly impact the satisfaction of the used trading app service. Second, the usefulness of the used trading app service will have a moderating effect on the effect of the authenticity of the used trading app service on the satisfaction of the used trading app service. Third, the ease of the used trading app service will have a moderating effect on the authenticity of the used trading app service on the satisfaction of the used trading app service. As a result of the study, the authenticity of the used trading app service significantly affected the satisfaction of the used trading app service. Appeared to be The results of this study will help understand used transaction app services where consumption of used products occurs from the viewpoint of product circular use behavior and can be used as a strategic plan to promote the use of used transaction apps in the future.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.3
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• pp.123-129
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• 2018

Ink-jet printing technology with ceramic ink of the four digital primary colors (cyan, magenta, yellow, and black; CMYK) can provide stable coloration even in the high-temperature firing process. Ceramic ink-jet printing can be widely applied in construction and ceramic industries due to the advantages of accurate and fast printing process of digital images for various products. Generally, organic solvent with proper viscosity and surface tension has been used in digital ink-jet printing process. However, the needs of ceramic ink without VOCs emission is increasing. In the present study, eco-friendly ceramic ink was synthesized by combining alumino boro-silicate glass frit and $CoAl_2O_4$ inorganic pigment based on an aqueous solvent that does not generate VOCs. The rheological properties and dispersion stability of aqueous ceramic ink were optimized. Jetting behavior and printing characteristics of the ceramic ink were also investigated in detail. As a result, the formulated aqueous ceramic complex ink showed a suitable jetting behavior without satellite drop by adjusting viscosity and surface tension. The ceramic ink can be printed on glass substrate with minimized spreading phenomena duo to high contact angle.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.35 no.1
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• pp.83-89
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• 2017

The Jeju Olle Trail Route No. 1 has opened in 2007, and over one million visitors per year trek total of 26 Olle trails throughout the island of Jeju as of 2017. The Olle trekking is one of eco-friendly tourism activities in the era of social issues with environmental collapse and threats. Up until now, studies on the Jeju Olle trail are focused on the visitors while the studies on residents who are the other major pillar of Jeju Olle trail have been limited. The study aims to compare the visit types, satisfaction level and pro-environmental behaviors between the visitors and residents on Jeju Olle trails. Total of 290 survey was collected in three month period from December, 2016 to February, 2017. The survey result indicates the Jeju residents trek the Jeju Olle in a larger group than the Jeju Olle visiting trekkers and show lower level in the visit satisfaction and pro-environmental behaviors. The noticeable lower level in the pro-environmental behaviors of residents can directly connect to the issue of Jeju environment as a whole, and the continuing environmental education program and promotion for residents to improve the pro-environmental behavior level is essential.

• Journal of Korean Society of Transportation
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• v.35 no.3
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• pp.210-219
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• 2017

Electric vehicles, which are attracting attention as eco-friendly vehicles, have been increasing in number since 2011 in Korea. The purpose of this study is to analyze the efficient operation of existing charging stations and factors to consider when installing additional charging stations based on the case of Jeju Island where the electric vehicle penetration rate is high and the charging infrastructure is relatively well established. The characteristics of using electric car charging stations by region, type of facility, and time of day are analyzed. As a result of analyzing the frequency of using the charger installed in Jeju Island, the utilization of both the fast charger and the slow charger is found to be concentrated in a specific area. The usage rate of charger installed in a business facility and a public parking lot is high in both fast charger and slow charger. However, according to the usage rate by time of day, the fast charger has a high utilization rate throughout the afternoon, while the use of a slow charger is concentrated in the morning. In order to enable users to utilize the electric vehicle charging station efficiently, it is necessary to provide a publicity guide for the charging station having a low utilization rate, a notice for using the charger, and a notification of completion of charging. Considering the charging demand, the area where the charger is not yet installed should be considered as the area to install the charger, and in addition, the additional installation should be considered in the area and the facility where the amount of charge is large. Service improvement is expected to be possible by utilizing actual electric vehicle charging behavior analysis result.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.21-31
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• 2017

Geobag method is an eco-friendly method to minimize the impact on the environment in the construction of retaining wall structure as a kind of geosynthetic reinforced retaining walls. In this study, evaluated behavior of full scaled geobag retaining wall about four different types of geobag retaining walls, that is, non-compacted geobags wall, compacted geobag wall, combination of longitudinal and transversal laied geobags wall, gabion and geobag wall were constructed in the field with instrumentation. Based on the results of field measurement, transversal layered geobag wall for non-compacted case was displaced 30% more than that of mixed gabion wall. Also, the more than 2m geobag walls without reinforcement at the backfill area are turned out to be unstable in terms of wall displacement. On the one hand, the distribution of the earth pressure for all geobag retaining walls sites show within the range of Rankine's and Coulomb's earth pressure after construction. But after intensity rainfall, the transversal laied geobag walls significantly increment of soil pressure. The geobag walls which constructed in the way of mixed wall systems such as gabion and geobag, longitudinal and transversal laied geobags are much stable with comparison of transversal laied geobag wall.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.151-161
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• 2016

As part of a policy to address climate change and pollution problem, the government introduced a green credit card scheme in order to motivate pro-environmental behaviors in July 2011. It is important to present the specific ways to facilitate pro-environmental behaviors using the consumer behavior pattern data. This study was a result of data from total fifty seven thousands customer purchasing history data of green credit card to be created for the 3 months from January to March 2015. As the analysis process is put in to operation the analysis of the purchasing customer's profile firstly, and the second come into association analysis to consider the buying associations for green products purchasing networks, the third estimate the useful parameters to affect the customer's pro-environmental behavior and customer characteristics. It shows that royal customers are from 30 to 40 years old and their incomes are from 30 million won to 40 million won. Especially, they live in Daegu, Gyeonggi, and Seoul.

• Resources Recycling
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• v.22 no.5
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• pp.13-19
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• 2013

The effect of pH on the citrate leaching behavior of heavy metal ion was investigated to develop an eco-friendly process for removing heavy metals from soil contaminated with copper, zinc, and lead. The leaching tests were performed using citrate solution with pH adjusted by mixing citric acid and sodium citrate under the following leaching conditions: particle size, under $75{\mu}m$; temperature, $50^{\circ}C$; citrate concentration, $1kmol/m^3$; pulp density, 5%; shaking speed, 100 rpm; leaching time, 1 hour. The difference of pH before and after the leaching test was not observed, and this result indicates the direct effect of hydrogen ion concentration on the leaching of metals was insignificant. The removal ratios of copper, zinc, and lead from the contaminated soil decreased with increasing pH. The thermodynamic calculation suggests that the leaching behaviors of metal ions were determined by two reactions; one is the reaction to form complex ions between heavy metal ions and citrate ion species, and the other is the reaction to form metal hydroxide between heavy metal ions and hydroxide ion.