• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.9
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• pp.2073-2085
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• 2012

Recently, the International Telecommunication Union allocated the 470-862 MHz band to the digital broadcasting (DB) service. Moreover, the 790-862 MHz sub-band will be allocated to the next-generation mobile system, known as the International Mobile Telecommunication - Advanced (IMT-A), and to the DB on a co-primary basis in the year 2015. Currently, two candidate technologies are available to represent the IMT-A system; the Mobile WiMAX and Long Term Evolution - Advanced (LTE-A). One of the main criteria of the IMT-A candidate is to not cause additional interference to the primary service (i.e., DB). In this paper, we address the spectrum sharing issue between the IMT-A candidates and the DB service. More precisely, we investigate the interference effect between the DB service and the mobile network, which could be either LTE-A or WiMAX. Our study proposes a spectrum sharing model to take into account the impact of interference and evaluates the spectrum sharing requirements such as frequency separation and separation distance. This model considers three spectrum sharing scenarios: co-channel, zero guard band, and adjacent channel. A statistical analysis is performed, by considering the interferer spectrum emission mask and victim receiver blocking techniques. The interference-to-noise ratio is used as an essential spectrum sharing criterion between the systems. The model considers the random distribution of the users, antenna heights, and the bandwidth effect as well as the deployment environment in order to achieve spectrum sharing. The results show that LTE-A is preferable to WiMAX in terms of having less interference impact on DB; this can eventually allow the operation of both services without performance degradation and thus will lead to efficient utilization of the radio spectrum.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.2-4
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• 2018

Most people cause disputes not to do things they do not want to do. Therefore, in this study, the mobile roulette system was studied to make role sharing easy and fun. The role sharing method is to rotate the roulette through the mobile application installed on the smartphone and throw the dart to check the result with the mobile application. Through this study, it is possible to set the role sharing that most people do not like to be as fun as the game, and the conflict due to the role sharing between family members can be reduced. It is also expected that it will contribute to leisure activities, not just unconditional roles.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.706-709
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• 2008

With the increasing popularity of P2P file sharing and advancement of mobile technologies, mobile P2P has revealed its attraction. Anonymity has become an increasing requirement in mobile networks. To reduce receiving garbage files, file validation and filtering are other requirements in the mobile P2P environment. If there are effective file filtering and validation mechanism, nodes' battery duration will be saved. In this paper, we do an analysis of security and anonymity in P2P file sharing and exchange system in mobile ad hoc environment, and propose a new efficient anonymous protocol, which can provide anonymity by broadcasting with a probabilistic algorithm and hiding real hop count information, the file validation by the file's special hash value and file filtering mechanism through the collaboration of middle nodes.

• Journal of The Korean Association of Information Education
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• v.10 no.2
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• pp.273-280
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• 2006

Most homepages of schools are available to publicize activities of education, to load educational materials efficiently. But we can't use current homepages of schools in making characteristic information or sharing educational resources. In this study, this CUBE system with RSS and mobile phone was designed and embodied for sharing characteristic educational activities and works in schools. Currently, CUBE is being under experimental test in elementry schools at Sancheong area, and instructors and students are operating CUBE for sharing education activities and making community in this system,.

• Journal of the Korean Society of Safety
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• v.33 no.1
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• pp.54-61
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• 2018

In this study, we developed a system for information sharing and cooperation support system among the accident response organizations to enable prompt and efficient response in responding to chemical accidents. In other words, by applying mobile messenger function, it is proposed to improve the chemical accident response system that provides information necessary for accident response promptly and accurately, and facilitates bi-directional communication between accident response organizations and field responders, thereby enabling efficient and organic response. As a result of comparing the information provision time before and after the chemical accident of chemical accident response information sharing system, the ratio of processing of substance information and chemical air diffusion information within 30 minutes was improved by 8% and 32%, respectively. As a result of this study, applying the chemical accident response information sharing system to the chemical accident response is expected to contribute to the improvement of the system and the ability to cope with the accident more effectively.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.4
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• pp.202-208
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• 2020

Recently, the importance of non-face-to-face has been emphasized due to COVID-19, and the use of sharing spaces is also expanding. The use of uncontact check-in technology for access control of sharing spaces reduces waiting time and optimizes workers' efficiency, resulting in operational cost savings. In this paper, we propose a sharing space access management system based on a mobile key and RCU (Room Control Unit), access to the facility using a mobile key, and monitor the facility using an RCU. Proposal system is for shared accommodation, rental field (residence, sale-selling hotel), shared office, etc. when there is a one-time visitor on a specific day and time, the corresponding password is delivered to the mobile platform to expose and key the existing password. It is supported by a field-adaptive system that can reduce discomfort such as delivery. In order to test the operation of the proposed integrated system, tests were conducted according to scenarios to understand the overall status of the user's reservation, check-in, and check-out, and a 100% success rate was derived for each item by setting performance indicators to prove test reliability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.802-804
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• 2017

Nowadays the development of mobile systems occupies significant part of our life, and users using mobile phones are demanding the utilization of differentiated spatial information. A study on application which provides information according to individual location information such as mobile advertisement is conducted for the location-based mobile service. In order to allow mobile phone users to share information based on local information, this paper proposes a mobile sharing system which combines social networks and location-based service to provide efficient information based on location information in mobile phones. The application can be provided with information associated with its location when the mobile phone user arrives at a specific location. Another proposed method focuses on providing more appropriate services for individual situations compared to other applications, and can contribute to expanding social networking functions to facilitate information sharing among users.

• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.641-646
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• 2011

In this paper, we investigate a power control problem which is very critical in underlay-based spectrum sharing systems. Although an underlay-based spectrum sharing system is more efficient compared to an overlay-based spectrum sharing system in terms of spectral utilization, some practical problems obstruct its commercialization. One of them is a real-time-based power adaptation of secondary transmitters. In the underlay-based spectrum sharing system, it is essential to adapt secondary user's transmit power to interference channel states to secure primary users' communication. Thus, we propose a practical power control scheme for secondary transmitters. The feedback overhead of our proposed scheme is insignificant because it requires one-bit signaling, while the optimal power control scheme requires the perfect information of channel states. In addition, the proposed scheme is robust to feedback delay. We compare the performance of the optimal and proposed schemes in terms of primary user's outage probability and secondary user's throughput. Our simulation results show that the proposed scheme is almost optimal in terms of both primary user's outage probability and secondary user's throughput when the secondary user's transmit power is low. As the secondary user's transmit power increases, the primary user's outage probability of the proposed scheme is degraded compared with the optimal scheme while the secondary user's throughput still approaches that of the optimal scheme. If the feedback delay is considered, however, the proposed scheme approaches the optimal scheme in terms of both the primary user's outage probability and secondary user's throughput regardless of the secondary user's transmit power.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.5
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• pp.1231-1236
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• 2014

Recently, diffusion and proliferation of mobile devices increases, per person n opens for the mobile device era. Mobile devices and OS types of continuously growing trend. More than 80% of market share with Google's Android and Apple's iOS as well as Samsung and Intel is developing TIZEN, Linux and Mobile was the UBUNTU which UBUNTU for Phone, UBUNTU touch, Mozilla 's Firefox OS, Microsoft 's windows mobile and many more OS are ahead of the launch. But different OS can share files between systems or technology is not. Bluetooth or WIFI Direct such technologies are present but can be transferred between compatible devices low, resulting in constraints file types also exist. In this paper, is equipped with a WiFi card in an environment where the Android mobile OS party this model and method for sharing files between different research and can share the file system based on research on.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.3
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• pp.86-96
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• 2008

In ubiquitous environments, invisible devices and software are connected to one another to provide convenient services to users. In order to provide such services, we must have mobile devices that connect users and services. However, the types of available services have thus far been limited due to the limited resources of mobile devices. This paper proposes a solution to the resource limitation problem of mobile devices by presenting a context-based collaboration system that allows mobile devices to share various nearby resources. Our system has a feature to enable personalized resource sharing by dynamically re-configuring user's preference and resource information.