Journal of the Korea Society of Computer and Information
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v.23
no.12
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pp.227-232
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2018
The purpose of this study is to empirically measure the consumer response to mobile phone price changes in small and medium cities that have been alienated from Chinese marketing research. To do this, we measured price response through consumer survey based on conjoint analysis. The results of this study are as follows. First, it show a typical pattern in which the part-worth decreases as the price increases. This suggests that there is room for improvement in profitability through pricing strategy for small and medium cities. Second, the decrease of the utility value according to the price increase was different for each city. This implies that difference of price response by city should be used strategically when planning price tactics. This study has contributed to understanding the expansion of research subjects from large cities to small cities and the price response phenomenon of small cities. And it will provide basic data on price response to mobile phone marketers of small and medium cities.
The purpose of this study was to investigate pre-service elementary school teachers' understanding about alternative energy and to identify their alternative conceptions. The two-tier instrument had been developed by Cheong et al. (2015) were used for this study. Twelve items from the instrument consisted of four categories: 'source of alternative energy', 'greenhouse gas emission', 'cost in electricity and construction' and 'advantages and disadvantages'. One hundred and fifteen pre-service elementary school teachers were participated in online survey during the semester. The results analyzed using SPSS 26.0. were as follows: First, the correct response rate varied depending on the content of item. Items related to characteristics and advantages & disadvantages of alternative energy showed high percentage of correct answers. Whereas, items regarding the principles of alternative energy showed relatively low percentage of correct answers. Second, there are some items showing statistically meaningful differences according to students' high school track. Nevertheless, there are no significant differences in overall. Third, we identified twelve alternative conceptions about alternative energy from students' answer distribution. Educational implications were discussed based on the results.
Wang, Yufeng;Erturk, Mustafa Cenk;Liu, Jinxing;Ra, In-ho;Sankar, Ravi;Morgera, Salvatore
Journal of Communications and Networks
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v.17
no.1
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pp.58-66
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2015
Aeronautical communication networks (ACN) is an emerging concept in which aeronautical stations (AS) are considered as a part of multi-tier network for the future wireless communication system. An AS could be a commercial plane, helicopter, or any other low orbit station, i.e., Unmanned air vehicle, high altitude platform. The goal of ACN is to provide high throughput and cost effective communication network for aeronautical applications (i.e., Air traffic control (ATC), air traffic management (ATM) communications, and commercial in-flight Internet activities), and terrestrial networks by using aeronautical platforms as a backbone. In this paper, we investigate the issues about connectivity, throughput, and delay in ACN. First, topology of ACN is presented as a simple mobile ad hoc network and connectivity analysis is provided. Then, by using information obtained from connectivity analysis, we investigate two communication models, i.e., single-hop and two-hop, in which each source AS is communicating with its destination AS with or without the help of intermediate relay AS, respectively. In our throughput analysis, we use the method of finding the maximum number of concurrent successful transmissions to derive ACN throughput upper bounds for the two communication models. We conclude that the two-hop model achieves greater throughput scaling than the single-hop model for ACN and multi-hop models cannot achieve better throughput scaling than two-hop model. Furthermore, since delay issue is more salient in two-hop communication, we characterize the delay performance and derive the closed-form average end-to-end delay for the two-hop model. Finally, computer simulations are performed and it is shown that ACN is robust in terms of throughput and delay performances.
Journal of Korean Society for Atmospheric Environment
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v.30
no.4
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pp.301-310
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2014
Country-specific data for net calorific values and carbon emission factors requires for a higher tier estimate of greenhouse gas emissions in the energy sector. The objective of this study is to develop country-specific net calorific values and carbon emission factors for petroleum energy produced in Korea. Calorific values and carbon contents of the fuels were measured using the oxygen bomb calorimeter method and the CHN elemental analysis method, respectively. Sulfur and hydrogen contents, which were used to calculate the net calorific value, were also measured and then net calorific values and carbon emission factors were determined based on the measurement results. The net calorific values and carbon emission factors determined for the petroleum produced in Korea 2012 and 2013 were compared to those in the 2006 IPCC Guidelines. Most of the values were different compared with the default values of the 2006 IPCC Guidelines although those were placed within their upper and lower limits. Time series analysis results showed inconsistent seasonal variation for the net calorific values and carbon emission factors.
Purpose: This research is the impact of service quality of Economy Hotels on customer satisfaction and Re-visit Intention in China. It reviews the empirical theories about Economy Hotels at home and abroad, based on SERVPERF, combines with the actual situation of China's Economy Hotels, and then constructs based on the research results at home and abroad. In the subfactor of service quality, "recovery" is added, and the relationship model between the service quality of Economy Hotel, customer satisfaction and Re-visit Intention is designed, in which the mediated effect of "customer satisfaction" between the service quality's subfactor and Re-visit Intentio is explored. Methods: 334 questionnaires were distributed to the check-in guests of three Home Inns in China's first-tier cities (ShangHai,BeiJing,ShenZhen), of which 300 were valid for data analysis. Result: The data analysis results show that the Economy Hotels' subfactor of service quality have a positive impact on customer satisfaction and Re-visit Intention, and customer satisfaction also plays an mediated effect. (partial mediation: tangible, reliability, recovery; full mediation: responsiveness, assurance, empathy) Conclusion: The research puts forward the enlightenment points for the development of Economic Hotels through the differences in the development emphasis and service quality between Economic hotels and other types of hotels, so as to improve the satisfaction and market competitiveness of China's Economic hotels through the research results.
Journal of the Institute of Electronics Engineers of Korea TC
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v.44
no.8
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pp.23-32
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2007
We propose a group-based security scheme for hierarchical wireless sensor networks. We model the network for secure routing with 3-tier sensor network comprised of three types of nodes: Base Station, Group Dominator and ordinary Sensor Nodes. Group-based deployment is performed using Gaussian (normal) distribution and show that more than 85% network connectivity can be achieved with the proposed model. The small groups with pre-shared secrets form the secure groups where group dominators form the backbone of the entire network. The scheme is devised for dealing with sensory data aggregated by groups of collocated sensors; i.e., local sensed data are collected by the dominating nodes and sent an aggregated packet to the base station via other group dominators. The scheme is shown to be light-weight, and it offers a stronger defense against node capture attacks. Analysis and simulation results are presented to defend our proposal. Analysis shows that robustness can significantly be improved by increasing the deployment density using both the dominating and/or ordinary sensor nodes.
Current methods to estimate the earth pressure for retaining wall analysis are based on Rankine or Coulomb approaches, in which the soil mass behind wall is assumed to reach to failure state with sufficient lateral movements. Some of recent research works carried out by field measurements reveal that the active earth. pressures by Ranking or Coulomb method are underestimated. It means that the lateral movements of wall and soil would not be mobilized enough to reach the failure state. In this study, the finite element method with Drucker -Prager model for soil is employed to investigate the behavior of concrete cantile,tier retaining wall, together with the influence of inclined backfill. The results indicate that the earth pressures on the retaining wall are strongly related to the mobilized lateral movements of wall and soil and that Ranking and Coulomb methods underestimate the resultant earth pressures and the increasing effect on earth pressure by inclined backfill. Based on this study, a simplified method to determine to earth pressures on cantilever retaining wall with horizontal backfill is proposed.
The Journal of Korean Institute of Communications and Information Sciences
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v.34
no.6A
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pp.476-483
/
2009
Recently much attention has been devoted to femtocell's potential to improve indoor cellular coverage and high speed wireless communications. Femtocell based commercial services have been already launched in some countries and standardization activities are actively on-going, there has been concern however over potential issues of interference between femtocells and the micro/macro networks. With universal frequency reuse, the ensuing cross-tier interference causes unacceptable data rate and outage probability, so an analysis of effect of interference in femtocell embedded networks would be necessary for a stable system design. This paper investigates the effect of interference on system performances of femtocell embedded hierarchical cell structure (HCS) networks considering the characteristics of propagation environments. Various channel parameters are specially considered for indoor environments where most of femtocells are deployed to investigate the effect of interference of femtocell embedded RCS networks. System capacity and coverage are provided with variant distance between macrocell and femtocell, location of the user in femtocell coverage, and characteristic of building structures.
With the tightening of environmental regulations (i.e., IMO Tier III), natural gas (NG) has been spotlighted as an eco-friendly fuel with few air pollutants other than nitrogen oxides (NOx) and sulfur oxides (SOx). For reasons of economic efficiency, it is mainly stored and transported in a liquid state at $-163^{\circ}C$, which is a cryogenic temperature, using a liquefied gas storage tank. Accordingly, it is necessary to reduce the boil-off gas (BOG) occurrence due to the heat flow according to the temperature difference between the inside and outside of the storage tank. Therefore, in this study, a BOG measurement test on an independent-type storage tank made up of SUS304L was carried out. The test results showed the tendency for BOG occurrence according to the temperature under different filling ratios.
Park, Jun Hyung;Kwahk, Kee-Young;Han, Heejun;Kim, Yunjeong
Journal of Intelligence and Information Systems
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v.19
no.4
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pp.21-37
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2013
Recently, as the advent of the knowledge-based society, there are more people getting interested in the intellectual property. Especially, the ICT companies leading the high-tech industry are working hard to strive for systematic management of intellectual property. As we know, the patent information represents the intellectual capital of the company. Also now the quantitative analysis on the continuously accumulated patent information becomes possible. The analysis at various levels becomes also possible by utilizing the patent information, ranging from the patent level to the enterprise level, industrial level and country level. Through the patent information, we can identify the technology status and analyze the impact of the performance. We are also able to find out the flow of the knowledge through the network analysis. By that, we can not only identify the changes in technology, but also predict the direction of the future research. In the field using the network analysis there are two important analyses which utilize the patent citation information; citation indicator analysis utilizing the frequency of the citation and network analysis based on the citation relationships. Furthermore, this study analyzes whether there are any impacts between the size of the company and patent citation relationships. 74 S&P 500 registered companies that provide IT and communication services are selected for this study. In order to determine the relationship of patent citation between the companies, the patent citation in 2009 and 2010 is collected and sociomatrices which show the patent citation relationship between the companies are created. In addition, the companies' total assets are collected as an index of company size. The distance between companies is defined as the absolute value of the difference between the total assets. And simple differences are considered to be described as the hierarchy of the company. The QAP Correlation analysis and MR-QAP analysis is carried out by using the distance and hierarchy between companies, and also the sociomatrices that shows the patent citation in 2009 and 2010. Through the result of QAP Correlation analysis, the patent citation relationship between companies in the 2009's company's patent citation network and the 2010's company's patent citation network shows the highest correlation. In addition, positive correlation is shown in the patent citation relationships between companies and the distance between companies. This is because the patent citation relationship is increased when there is a difference of size between companies. Not only that, negative correlation is found through the analysis using the patent citation relationship between companies and the hierarchy between companies. Relatively it is indicated that there is a high evaluation about the patent of the higher tier companies influenced toward the lower tier companies. MR-QAP analysis is carried out as follow. The sociomatrix that is generated by using the year 2010 patent citation relationship is used as the dependent variable. Additionally the 2009's company's patent citation network and the distance and hierarchy networks between the companies are used as the independent variables. This study performed MR-QAP analysis to find the main factors influencing the patent citation relationship between the companies in 2010. The analysis results show that all independent variables have positively influenced the 2010's patent citation relationship between the companies. In particular, the 2009's patent citation relationship between the companies has the most significant impact on the 2010's, which means that there is consecutiveness regarding the patent citation relationships. Through the result of QAP correlation analysis and MR-QAP analysis, the patent citation relationship between companies is affected by the size of the companies. But the most significant impact is the patent citation relationships that had been done in the past. The reason why we need to maintain the patent citation relationship between companies is it might be important in the use of strategic aspect of the companies to look into relationships to share intellectual property between each other, also seen as an important auxiliary of the partner companies to cooperate with.
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