• Current Photovoltaic Research
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• v.8 no.1
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• pp.6-11
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• 2020

The power conversion efficiency (PCE) of a two-terminal tandem solar cell depends upon the tunnel-recombination junction (TRJ) between the top and bottom sub-cells. An optimized TRJ in a tandem cell helps improve its open-circuit voltage (V_oc), short-circuit current density (J_sc), fill factor (FF), and efficiency (PCE). One of the parameters that affect the TRJ is the buffer layer thickness. Therefore, we investigated various TRJs by varying the thickness of the buffer or intermediate layer (TRJ-buffer) in between the highly doped p-type and n-type layers of the TRJ. The TRJ-buffer layer was p-type nc-Si:H, with a doping of 0.06%, an activation energy (E_a) of 43 meV, an optical gap (E_g) of 2.04 eV, and its thickness was varied from 0 nm to 125 nm. The tandem solar cells we investigated were a combination of a heterojunction with intrinsic thin layer (HIT) bottom sub-cell and an a-Si:H (amorphous silicon) top sub-cell. The initial cell efficiency without the TRJ buffer was 7.65% while with an optimized buffer layer, its efficiency improved to 11.74%, i.e., an improvement in efficiency by a factor of 1.53.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.488-490
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• 2009

The Spatial Image contents of Geomorphology 3-D environment is focused by the requirement and importance in the fields such as, national land development plan, telecommunication facility management, railway construction, general construction engineering, Ubiquitous city development, safety and disaster prevention engineering. The currently used DEM system using contour lines, which embodies geographic information based on the 2-D digital maps and facility information has limitation in implementation in reproducing the 3-D spatial city. Moreover, this method often neglects the altitude of the rail way infrastructure which has narrow width and long length. This As the results, We confirmed the solutions of varieties application for railway facilities management using 3-D spatial image contents and database design. Also, I suggested that U-city using topographical modeling about matching methods of high density elevation value using 3-D aerial photo with laser data are best approach for detail stereo modeling and simulation. There for of this, Using of rapid spatial information generation by various images and laser data through matching methods for the make of Spatial data base management inplementation are very powerful and much application of our life and real worlds.

• Journal of Digital Convergence
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• v.12 no.12
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• pp.13-22
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• 2014

The right to be forgotten is a world-wide issue after the decision of the European Court of Justice which accepted that right. This essay discusses about the guide lines for protecting the right to delete, a category of the right to be forgotten. I classified those guide lines as follows : (1) sensitiveness of the personal information, (2) offensiveness to reasonable and ordinary people, (3) intention of writing the article, (4) value of historical record, (5) importance of privacy comparing with right to know with time flow, (6) public figure, (7) article based on fact or opinion. To effectively protect right to be forgotten and delete, we have to consider Privacy Impact Assessment, using blind system, unification of multiple institutions, and reforming press arbitration system.

• Industry Promotion Research
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• v.5 no.1
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• pp.13-20
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• 2020

This study is about consumer preference of plastic toilets that can provide automatic supply of recycled water. First, the preference for plastic toilet seat design by gender and age group was preferred for gender type C and G for the sex. As the result of the chi-square test, the significance probability is .044 and the significance is P <.0 5. I could confirm that. Age, teens, 40 s, and 50 s or older prefer type C, 20 s and 30 s, but B type is not statistically significant. Second, the differences among the groups of preference for appearance design criteria according to general characteristics were all stable (stable appearance) in gender, age, region, education, and salary, but the chi-square test showed that they were not statistically significant. There was no difference between them. This study has implications for improving competitiveness and productivity by reducing the main production cost by commercializing toilets made of plastic materials.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.52.1-52.1
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• 2012

It is often said that there is little geometrical mind in Korean history. However, a method to project the surface of a sphere onto 2-dimensional plain was applied to the representative Korean star chart or Cheonsang Yeolcha Bunyajido (天象列次分野之圖). The method, called the equi-distant polar projection, was explained in detail in ancient Chinese history book of the Tang dynasty, which was originated from older history. Another method of the Mercator projection was introduced by the famous engineer Su Song (蘇頌) of the Song dynasty. The description has quite geometrical thoughts, especially the concept of infinity or convergence appears, However, this type of sky projection method was not widely used in east Asia. When the European Jesuits came to China to evangelize the Chinese people, they found that the Chinese people paid much attention to advanced European astronomical knowledge. Thus, they introduced the European astronomical knowledges into China, and the star chart was one of them. The projection method of the new charts were quite different from the Chinese tradition. When the Koreans brought those new star chart from China, they must have known the geometrical description of the method. The method was described in detail in a volume of Chongzhen Lishi (崇禎曆書) or Xiyang Xinfa Lishu (西洋新法曆書). The explanation consists of three part. One is the quantitative way; another is a geometrical way using axiomatic systems; and the other is the practical method to draw star chart with the geometical projection. However, when we see the Honcheon Jeondo (渾天全圖) that is thought to be duplicated by Kim Jeongho (金正浩), the new geometrical method was not so widely known to the Koreans. I will discuss the reason why the geometrical minds have not been widely adopted in the Korean civilization.

• Journal of Digital Convergence
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• v.15 no.3
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• pp.295-300
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• 2017

The purpose of this study is to analyze the EBS special lecture, which is an educational application, from a user 's point of view and to propose a direction for improvement of the user experience according to the GUI design. Firstly, we surveyed the theoretical background and service situation through literature review, and secondly, we surveyed the user experience questionnaire based on 7 principles of honeycomb model of Peter Morville. As a result, the EBS special lecture showed improvement of GUI due to lack of visual part in addition to its use. Based on this research, I hope that the service for improvement of the user experience of the education application will be improved in the future and it will be helpful to study the educational application user experience to be conducted in the future.

• Journal of the Korea Furniture Society
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• v.22 no.3
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• pp.160-173
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• 2011

Increased internet use under a ubiquitous environment may be called as a great human information space revolution followed by Industrial Revolution. This revolution is exerting its significant influence over all the industry as a whole with speed faster than that of any other times. Along with this trend, if furniture design field that leads living culture should fail to jump on this main stream without noticing it, it may be reduced to a unpopular field some day without any sign of recovery. Under this background, this study is intended to recognize a goal aiming at understanding our rapidly changing living environment and leading our way positively. Currently, our surrounding living environment is immersed in computers here and there and Mark Weiser once defined a system that moves in advance before an action as ubiquitous computing and in this respect, I am going to observe a detailed transformation process of space. First nature of the space may be defined as atoms, a physical space equivalent to a spatial element and Bits space that is untouchable is usually called as 2nd space and a combination of atoms and Bits is an intelligent space - 3rd space - that can be intelligible without touching it and finally, this space is called as a ubiquitous space. This spatial transformation is developed by several changes of living environment and we may call it as living trend or interior design trend. Transformation in terms of social perspective, space structural perspective and digital technique perspective may be enumerated. These transformations were surveyed based on its contents being implemented at a future housing exhibition hosted by 5 construction companies along with fusion of information furniture and furniture depending on each housing space. In conclusion, it could be realized that most of the companies were decorating future space by implementing ubiquitous environment as a success factor of future housing market. It may be meaningful to note once again that under an interior environment, a fusion of furniture and information furniture is required considering interior trend elements.

• Journal of Digital Convergence
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• v.5 no.2
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• pp.99-108
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• 2007

As the transaction using mail order sales mediating sites such as Auction rapidly increase, consumer damages are also increasing. Therefore, in this study, the methods to remedy consumer damages occurring from transactions through mail order sales mediating sites such as the Payment Deposit System, the systems to resolve disputes without any litigation and the systems in relation to the Consumer Basic Act have been examined and measures to improve the systems have been groped. For the transactions using mail order sales intermediating sites, it is necessary to impose more responsibility on mail order sales mediators although the responsibility may not be required to be at the level of mail order sellers such as internet shopping malls. Therefore, institutional supports are necessary to effectively protect consumers in the transactions using mail order sales mediating sites and to induce damaged consumers to actively file claims for compensations. In relation to this, the Collective Dispute Mediation System and the Consumer Group Litigation System under the Consumer Basic Act may become good examples. The consumers who have been subject to the same or similar damages in the transactions using mail order sales mediating sites should also be allowed to participate in the Collective Dispute Mediation under the Consumer Basic Act or actively utilize the Consumer Group Litigation System. Also, it is desirable to reflect these systems on 'the Act on Consumer Protection in E-Commerce etc' so that these systems can also be directly applied to the transactions using mail order sales mediating sites.

• Journal of Digital Convergence
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• v.10 no.4
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• pp.257-263
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• 2012

Smart phones become popular all over the world recently. At the same time, demand of various additional services, such as SNS by utilizing low-cost reliable Wi-Fi network and position information, is expected to keep growing. In this paper, Implementation of SNS based on an Open Wi-Fi & Position Information was proposed. This service is achieved by constructing an Open Wi-Fi network based on a built AP access information database. And in order to provide durable connection in mobile environment, RSS detect AP switching module and mobile IP are utilized in the proposed service. Furthermore, with the utilization of GPS information of AP, AP providers could delivery various information such as advertisements, promotion events. In addition, it is possible for AP users to communicate with each other, thus a position information based SNS was also proposed in this paper.

• Journal of Digital Convergence
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• v.14 no.8
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• pp.453-460
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• 2016

This study aimed to compare the systems of ticketing application programs of three major movie theaters, CGV, Megabox, Lotte Cinema, with each other and evaluate the usability, and find problems to figure out user experiences for more convenient mobile ticketing. Experimental subjects with experiences of using apps of the movie theaters were recruited; First, as a primary task, they reserved movie tickets with each of the movie theater apps; Second, they had in-depth interviews with questions based on the model of Creating Pleasurable Interfaces by Stephen Anderson. As a result, users preferred the composition with information in order in overall, in which ticketing process went smoothly. In particular, users were more satisfied with convenient payment applications. Therefore, as an improving way, it is required to design an interface for users to recognize at a glance and a payment system within an app, not to design separate payment system out of the app. I hope this study will help actively conduct researches to maximize the usability in a way to reserve movie tickets through smartphone apps.