• Journal of Computing Science and Engineering
• /
• v.4 no.2
• /
• pp.173-187
• /
• 2010

Recent technological advances in mobile communication systems have made explosive growth in the number of mobile device users worldwide. One of the most important issues in designing a mobile computing system is location management of users. The hierarchical systems had been proposed to solve the scalability problem in location management. The scalability problem occurs when there are too many users for a mobile system to handle, as the system is likely to react slow or even get down due to late updates of the location databases. In this paper, we propose a top-down clustering algorithm for hierarchical location database systems in a wireless network. A hierarchical location database system employs a tree structure. The proposed algorithm uses a top-down approach and utilizes the number of visits to each cell made by the users along with the movement information between a pair of adjacent cells. We then present a modified algorithm by incorporating the exhaustive method when there remain a few levels of the tree to be processed. We also propose a capacity constraint top-down clustering algorithm for more realistic environments where a database has a capacity limit. By the capacity of a database we mean the maximum number of mobile device users in the cells that can be handled by the database. This algorithm reduces a number of databases used for the system and improves the update performance. The experimental results show that the proposed, top-down, modified top-down, and capacity constraint top-down clustering algorithms reduce the update cost by 17.0%, 18.0%, 24.1%, the update time by about 43.0%, 39.0%, 42.3%, respectively. The capacity constraint algorithm reduces the average number of databases used for the system by 23.9% over other algorithms.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.10
• /
• pp.4250-4267
• /
• 2015

Although many revocable group signature schemes has been proposed in vehicular ad hoc networks (VANETs), the existing schemes suffer from long computation delay on revocation that they cannot adapt to the dynamic VANETs. Based on Chinese remainder theorem and Schnorr signature algorithm, this paper proposes an efficient revocable group signature scheme in VANETs. In the proposed scheme, it only need to update the corresponding group public key when a member quits the group, and in the meanwhile the key pairs of unchanged group members are not influenced. Furthermore, this scheme can achieve privacy protection by making use of blind certificates. Before joining to the VANETs, users register at local trusted agencies (LTAs) with their ID cards to obtain blind certificates. The blind certificate will be submitted to road-side units (RSUs) to verify the legality of users. Thus, the real identities of users can be protected. In addition, if there is a dispute, users can combine to submit open applications to RSUs against a disputed member. And LTAs can determine the real identity of the disputed member. Moreover, since the key pairs employed by a user are different in different groups, attackers are not able to track the movement of users with the obtained public keys in a group. Furthermore, performance analysis shows that proposed scheme has less computation cost than existing schemes.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.10
• /
• pp.4766-4786
• /
• 2016

Looking for missing companions who are out of touch in public places might suffer a long and painful process. With the help of mobile crowdsourcing, the missing person's location may be reported in a short time. In this paper, we propose MissingFound, an assistant system that applies mobile crowdsourcing for finding missing companions. Discovering valuable users who have chances to see the missing person is the most important task of MissingFound but also a big challenge with the requirements of saving battery and protecting users' location privacy. A customized metric is designed to measure the probability of seeing, according to users' movement traces represented by WiFi RSSI fingerprints. Since WiFi RSSI fingerprints provide no knowledge of users' physical locations, the computation of probability is too complex for practical use. By parallelizing the original sequential algorithms under MapReduce framework, the selecting process can be accomplished within a few minutes for 10 thousand users with records of several days. Experimental evaluation with 23 volunteers shows that MissingFound can select out the potential witnesses in reality and achieves a high accuracy (76.75% on average). We believe that MissingFound can help not only find missing companions, but other public services (e.g., controlling communicable diseases).

• Journal of Korea Multimedia Society
• /
• v.17 no.1
• /
• pp.77-93
• /
• 2014

Kinetic typography has been suggested to express emotions in computer-mediated communication (CMC) by empowering static texts with dynamic attributes, where conversations occur primarily in text-based forms. In this work, we investigate whether pre-defined kinetic typography effects are capable of delivering emotions, and further, which specific attributes of kinetic typography arouse such emotions. The results show that emotional response of users were corresponding to the emotions intended by experts, indicating that pre-defined kinetic typography is an applicable way to express emotions consistently in CMC. Also, results demonstrate some key attributes that derive certain levels of mood and energy respectively. Energy level turned out to be affected by the font size, transparency, direction of movement, amount of movement, velocity, and acceleration of the text, while mood level was influenced by the transparency, direction of movement, regularity in movement, and speed of the text.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.34 no.3 s.116
• /
• pp.32-40
• /
• 2006

We investigated space establishment and land use of children's parks by studying movement of users in and out of the parks with a questionnaire survey, video and analysis, and then analyzed the characteristics of how the facilities and the space of the parte are used. The results are as follows. First, when considering the character of the facilities of children's parks, entertainment facilities should receive priority followed by those for relaxation and those for convenience. When considering the position of facilities in the parks, because activity spaces may have similar functions to multi-purpose paved spaces, common use of these two spaces should be considered. Entrances and lines of movement should be kept in mind. Second, when considering the surrounding land uses, in case a play facility at a large-sized complex or an elementary school is adjacent, the exercise facilities may be more important, followed by play and rest facilities. In case there is a broad path around the parte, the way in which movement occurs into the central axis should be considered so that the other side of the broad way is not included in the children's play space. Third, proper control of roads adjacent to the parse is needed to protect children from danger.

• The Korean Journal of Archival Studies
• /
• no.68
• /
• pp.243-279
• /
• 2021

Rep. Roh Hoe-chan is a representative politician in Korean progressive politics. From the labor movement to the workers' political organization movement, they devoted themselves to the movement to build a progressive party. As a member of the 17th, 19th, and 20th National Assembly, he carried out legislative activities. The record he left is the record of the political power of workers, the record of the progressive party, and the record of a politician who suffers and practices. Also, as the son of a displaced person, as a student activist suffering from the restoration period, it is also a record of a human being of cultural literacy who played the cello. Archivist's basic research is expected to play a role in creating a virtuous cycle of archive management by structuring the archive and presenting various access points to various users, allowing more diverse research and use in the future.

• Journal of Korean Society of Archives and Records Management
• /
• v.23 no.4
• /
• pp.47-71
• /
• 2023

Korea is a record powerhouse nation with the largest number of Memory of the World in the Asia-Pacific; however, active utilization of archives for future generations has been lacking. Therefore, this study sought to enhance interest in archives and utilize them directly in school lessons. The Korean National Debt Redemption Movement's archives, which were selected as a Memory of the World, were used in the school lessons, and based on them, a library collaborative instruction design was developed. A library collaborative instruction is a collaboration between the high school Korean history subject and the library information literacy instruction, designed in three sessions. Through the literature research-based design, a library collaborative instruction plan, teaching and learning plan, and activity sheets were derived. Implementing this designed library collaborative instruction is expected to stimulate interest in the Memory of the World, linking curriculum and archives at schools and significantly expanding the users of the archives into teachers and students.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.4
• /
• pp.1849-1856
• /
• 2012

This paper proposes a method to track the center of pupil and perform the remote control for interface based on the substituted commands according to movements of pupil under smart phone environment. The proposed method, which is a remote control through the movement of eyes, may be helpful for the handicapped people or users who want a more convenient input method. A method based on webcam, which is representative one among the previous methods to track pupil of user, has a few limitations on distance and angle between location of user and webcam. However, this paper uses smart phone that is convenient to carry. The proposed method can perform the remote control through tracking of pupil using wireless network without any restriction on the location of users. Thus, the method is effectively applied for controlling the smart TV that should be controlled on the distance as well as the remote control for PC.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.10 no.4
• /
• pp.83-90
• /
• 2010

In this paper, we use VR technologies including touch processing technologies and haptic devices to offer touch of fish objects to users. The Omni, a kind of haptic device and made by Sensable Inc., is used to implement multi touch model in VR space. In addition, Matlab/Simulink and proSENSE Virtual Touch Toolbox of Handshake Inc., are used as programing tools. Functions needed to describe the movement of x, y, and z axis respectively are applied to delineate the natural movement of fish objects modeled with 3D. Such movements offer realistic physical interactions to two users controlling multi point respectively. In experiment, to perceive the appearance of 3D object by touch and to feel the respiration by touch are well conducted. We also verify that it is possible to develop games or contents through multi participation in VR Space by using multi point.

• Journal of Korea Game Society
• /
• v.16 no.6
• /
• pp.49-58
• /
• 2016

This paper proposes three schemes of one-hand control that can be used in the First-Person Viewpoint mobile games and evaluates them. Displaying virtual controllers on the screen, the existing mobile games use schema that allows users use both hands. In the First-Person Viewpoint mobile games, however, one-hand control is possible because smaller number of functions for viewpoint movement is required. This research proposes three one-hand control schemes for First-Person Viewpoint movement and rotation, and evaluates them using AHP. The experiment results prove that one-hand control schemes are more useful than both-hands control schemes for the mobile game users.