• Korean Institute of Interior Design Journal
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• v.21 no.2
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• pp.186-196
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• 2012

Information technology has changed the human life as well as the societal and economic paradigm. New office environments have been proposed to cope with emerging changes and to support working performances by reducing costs of office operation and business. Recently, office environments have adopted ubiquitous computing with a focus on collaboration to promote real-time enterprises. They become equipped with various mobile devices and pervasive technologies in wireless networks. This study aims to propose a direction for the adoption of mobile and pervasive computing on the new office environment. We investigate relate works and analyze new office types including mobile offices, telework centers and home offices. Using a customized questionnaire, the current conditions of the office environments and officers' demands were investigated and analyzed. In the end, we propose the direction for a ubiquitous office environment with a focus on two attributes, ubiquity and mobility. This research will be a basis for the development of ubiquitous offices that support the professionalism of works in practices.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1B
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• pp.9-18
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• 2006

Advances in wireless network are enabling the development of ubiquitous multimedia services. These multimedia services need efficient platforms to comply with the requirements of mobile computing. We introduce an adaptive service platform based on mobile agent and grid systems while specifying the challenges of ubiquitous multimedia services and focusing on frequent disconnections and scarce resources. We applied our platform to framework RtoA (Ready-to-Attend) which supports mobile users to access compute-intensive multimedia service, specifically, mobile education and video conferencing. RtoA includes hand-off, speaker and listener service which enable people to attend a conference or a class with satisfying quality of multimedia service. ns-2 based simulation verifies that our scheme is an efficient way to reduce energy consumption of mobile devices and to improve the response time of mobile applications.

• Asia pacific journal of information systems
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• v.16 no.3
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• pp.205-227
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• 2006

This study suggests major characteristics of the ubiquitous environment, which include pervasive connectivity, context awareness, and playfulness, by surveying mobile contents users. Also, this empirical study attempts to validate nine hypotheses and all the ubiquitous factors of mobile contents have positive effect on perceived interactivity. It is revealed that perceived interactivity is an intermediary factor which positively affects users' perceived performance, satisfaction and continuous use intention. Hypotheses of positive relationships among users' behavioral outcome factors are also accepted. Results show that ubiquitous characteristics of mobile contents influence the users' attitude and behavior through the intermediary role of perceived interactivity among users and messages and devices. This study contributes to the literature by presenting and empirically verifying the effect of ubiquitous factors of mobile contents and perceived interactivity on uses' attitude and behavior intention. Based on study results, user-oriented theoretical bases are provided for various mobile contents service, the issue of policy-making and business planning are addressed, and managerial implications are discussed.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.4 s.304
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• pp.25-32
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• 2005

The spread of mobile devices, PDAs and sensors has enabled the construction of ubiquitous computing environments, transforming regular physical spaces into 'Smart space' augmented with intelligence and enhanced with services. However, the deployment of this computing paradigm in real-life is disturbed by poor security, particularly, the lack of proper authentication and authorization techniques. Also, it is very important not only to find security measures but also to preserve user privacy in ubiquitous computing environments. In this Paper, we propose efficient user authentication and authorization model with anonymity for the privacy-preserving for ubiquitous computing environments. Our model is suitable for distributed environments with the computational constrained devices by using MAC-based anonymous certificate and security association token instead of using Public key encryption technique. And our Proposed Protocol is better than Kerberos system in sense of cryptographic computation processing.

• Journal of KIISE:Software and Applications
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• v.35 no.8
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• pp.512-521
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• 2008

Web-based information services should be evaluated for accessibility and usability with various types of Internet Web-browsing devices, interacting with web information servers. A reliable ubiquitous Web information server, accessible and usable with a variety of Web-browsing devices (e.g. a full-browsing mobile phone), should be a unified center for personalized ubiquitous Web information services as well as for business models based on personalized advertisements. We studied an estimation of the accessibility and usability in Web interaction for personalized ubiquitous Web information services, as metrics for real-time estimation. We show empirical results based on implementation and experiments in Korea, Japan and China, using a test-bed Web site ('ktrip.net') and single-character Korean domain names (e.g. 김.net, 이.net, 박.net, 최.net, ㄱ.net, ㄴ.net ... ㅎ.net, ㅏ.net, ... ㅔ.net, ㄱ.com, ㄴ.com ... ㅎ.com).

• Science of Emotion and Sensibility
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• v.10 no.4
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• pp.555-569
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• 2007

Ubiquitous computing environment is the new surroundings, currently being realized by modern technology. Since previous usability tests are not suitable for this new technological environment, new research on psychological factors needs to be conducted. The evaluation of service scenarios also will be required in tandem with traditional usability tests of operation devices. Consequently, this study classified usability factors from a scenario perspective and was conducted with a focus on the psychological elements of controllability from a mechanical perspective. Study 1 reclassified the factors of existing usability tests according to similarity and application scenarios, and ten important groups of factors were newly created. Study 2 focused specifically on the design side of a device and showed that the degree of familiarity with the ubiquitous computing device and its complexity brought about a difference in perceived controllability of the device.

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.59-75
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• 2006

In this paper, we propose a congestion control scheme to control the congestion due to the mobility of ubiquitous devices on ubiquitous computing environment. Especially, this congestion control scheme provides a reverse congestion avoidance state which can classify between packet error by features of wireless network and packet dropping by congestion. Also, it provides a slow stop state which can minimize bandwidth waste due to congestion control. The proposed congestion control scheme controls more adaptive than existing congestion control schemes. The proposed congestion control scheme is designed based on DCCP(Datagram Congestion Control Protocol) being proposed by IETF(Internet Engineering Task Force) and implemented on the Linux kernel. In simulation results, the proposed congestion control scheme provides good bandwidth throughput in wireless network as well as in wired network.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.5
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• pp.1-11
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• 2008

Wireless Sensor Networks is applied to improvement of life convenience or service like U-City as well as environment pollution, tunnel and structural health monitoring, storm, and earthquake diagnostic system. To increase the usability of sensor data and applicability, mobile devices and their facilities allow the applications of sensor networks to give mobile users and actuators the results of event detection at anytime and anywhere. In this paper, we present MUSNEMO(Multi-sensor centric Ubiquitous Smart sensor NEtwork using Mobile devices) developed system for providing more efficient and valuable information services with a variety of mobile devices and network camera integrated to WSN. Our system is performed based on IEEE 802.15.4 protocol stack. To validate system usability, we built sensor network environments where were equipped with five application sensors such magnetic, photodiode, microphone, motion and vibration. We also built and tested proposed MUSNEMO to provide a novel model for event detection systems with mobile framework.

• Korean Journal of Agricultural Science
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• v.38 no.4
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• pp.747-752
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• 2011

Wireless technology has enabled farmers monitor and control protected production environment more efficiently. Utilization of USN (Ubiquitous Sensor Network) devices also brought benefits due to reduced wiring and central data handling requirements. However, wireless communication loses signal under unfavorable conditions (e.g., blocked signal path, low signal intensity). In this paper, performance of commercial wireless communication devices were evaluated for application to protected crop production. Two different models of wireless communication devices were tested. Sensors used in the study were weather units installed outside and top of a greenhouse (wind velocity and direction, precipitation, temperature and humidity), inside ambient condition units (temperature, humidity, $CO_2$, and light intensity), and irrigation status units (irrigation flow and pressure, and soil water content). Performance of wireless communication was evaluated with and without crop. For a 2.4 GHz device, communication distance was decreased by about 10% when crops were present between the transmitting and receiving antennas installed on the ground, and the best performance was obtained when the antennas were installed 2 m above the crop canopy. When tested in a greenhouse, center of a greenhouse was chosen as the location of receiving antenna. The results would provide information useful for implementation of wireless environment monitoring system for protected crop production using USN devices.

• Journal of Information Processing Systems
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• v.14 no.2
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• pp.286-308
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• 2018

The availability of powerful and sensor-enabled mobile and Internet-connected devices have enabled the advent of the ubiquitous sensor network (USN) paradigm. USN provides various types of solutions to the general public in multiple sectors, including environmental monitoring, entertainment, transportation, security, and healthcare. Here, we explore and compare the features of wireless sensor networks and USN. Based on our extensive study, we classify the security- and privacy-related challenges of USNs. We identify and discuss solutions available to address these challenges. Finally, we briefly discuss open challenges for designing more secure and privacy-preserving approaches in next-generation USNs.