• Journal of Digital Contents Society
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• v.14 no.4
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• pp.419-428
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• 2013

Real-time accessibility and agility are required in u-commerce under ubiquitous computing environment. Most of the existing recommendation techniques adopt the method of evaluation based on personal profile, which has been identified with difficulties in accurately analyzing the customers' level of interest and tendencies, as well as the problems of cost, consequently leaving customers unsatisfied. Researches have been conducted to improve the accuracy of information such as the level of interest and tendencies of the customers. However, the problem lies not in the preconstructed database, but in generating new and diverse profiles that are used for the evaluation of the existing data. Also it is difficult to use the unique recommendation method with hierarchy of each customer who has various characteristics in the existing recommendation techniques. Accordingly, this dissertation used the implicit method without onerous question and answer to the users based on the data from purchasing, unlike the other evaluation techniques. We applied FRAT technique which can analyze the tendency of the various personalization and the exact customer.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.1023-1026
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• 2005

In the ubiquitous computing environment, an intelligent vehicle is defined as a sensor node with a capability of intelligence and communication in a wire and wireless network space. To make it real, a lot of problems should be addressed in the aspect of vehicle mobility, in-vehicle communication, common service platform and the connection of heterogeneous networks to provide a driver with several intelligent information services beyond the time and space. In this paper, we present an intelligent information system for managing in-vehicle sensor network and a vehicle gateway for connecting the external networks. The in-vehicle sensor network connected with several sensor nodes is used to collect sensor data and control the vehicle based on CAN protocol. Each sensor node is equipped with a reusable modular node architecture, which contains a common CAN stack, a message manager and an event handler. The vehicle gateway makes vehicle control and diagnosis from a remote host possible by connecting the in-vehicle sensor network with an external network. Specifically, it gives an access to the external mobile communication network such as CDMA. Some experiments was made to find out how long it takes to communicate between a vehicle's intelligent information system and an external server in the various environment. The results show that the average response time amounts to 776ms at fixed place, 707ms at rural area and 910ms at urban area.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.57-64
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• 2011

The NGN (Next Generation Network) means the kernel infrastructure technology to provide information and communication services which are able to be used at present and future when a ubiquitous computing era has been realized. In other words, NGN can be the frame providing the same information and communication services anytime and anywhere regardless of wire and wireless. The broadband convergence network that has been built in the public institution has established a broadband multimedia communication network supporting voice telephone, task net, internet network, video conference network, voice over IP (VoIP) network and etc. It is possible for a requested bandwidth and services to be served, only if a broadband convergence network provide the interoperability between the various classes which include a transport network layer, network control layer, service control layer and other layers. In this paper, we analyzed the interoperability issues of the present broadband convergence network and propose a guideline for the future one.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.6
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• pp.1069-1073
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• 2016

The Internet of Things (IoT) is the interconnection of uniquely identifiable embedded computing devices within the existing Internet infrastructure. IoT is expected to offer advanced connectivity of devices, systems, and services that goes beyond machine-to-machine communications and covers a variety of protocols, domains, and applications. Key system-level features that IoT needs to support can be summarized as device heterogeneity, scalability, ubiquitous data exchange through proximity wireless technologies, energy optimized solutions, localization and tracking capabilities, self-organization capabilities, semantic interoperability and data management, embedded security and privacy-preserving mechanisms. Time information is a critical piece of infrastructure for any distributed system. Time information and time synchronization are also fundamental building blocks in the IoT. The IoT requires new paradigms for combining time and data. This paper reviews conventional time keeping mechanisms in the Internet and presents issues to be considered for combining time and data in the IoT.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.469-473
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• 2006

Nowadays, to realize ubiquitous computing environment, many research activities have been going on within various kinds of research domains including automatic identification, sensor network, home network, telematics and so on. Especially, RFID middle-ware that supports the aggregation of RFID tag data, control and management, and the integration with legacy systems has recently gained a lot of attention. Meanwhile, EPCglobal defined an ALE(Application Level Events) standard specification, which exists between RFID readers and applications, and substitutes the previous systems called Savant. In the specification internal structures and implementation technologies of ALE are not mentioned and only external interfaces are defined. This approach easies the verification of standard compliance and inter-operability of the layer. In this paper, we present the design of ALE-compliant RFID middle-ware systems that process RFID tag data efficiently.

• Journal of KIISE:Software and Applications
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• v.32 no.4
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• pp.258-267
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• 2005

We propose the ubiFloor system to track and recognize users in ubiquitous computing environments such as ubiHome. Conventional user identification systems require users to carry tag sensors or use camera-based sensors to be very susceptible to environmental noise. Though floor-type systems may relieve these problems, high cost of load cell and DAQ boards makes the systems expensive. We propose the transparent user identification system, ubiFloor, exploiting user's walking pattern to recognize the user with a set of simple ON/OFF switch sensors. The experimental results show that the proposed system can recognize the 10 enrolled users at the correct recognition rate of $90\%$ without users' awareness of the system.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.2
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• pp.143-149
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• 2008

A novel compact model for a five-port transformer balun is proposed for the efficient circuit design of hybrid balun. Compared to the conventional model, the proposed model provides much faster computation time and more reasonable values for the extracted parameters. The hybrid balun, realized in $0.18\;{\mu}m$ CMOS, achieves 2.8 dB higher gain and 1.9 dB lower noise figure than its passive counterpart only at a current consumption of 0.67 mA from 1.2 V supply. By employing the hybrid balun, a differential zero-IF receiver is designed in $0.18\;{\mu}m$ CMOS for IEEE 802.15.4 ZigBee applications. It is composed of a differential cascode LNA, passive mixers, and active RC filters. Comparative investigations on the three receiver designs, each employing the hybrid balun, a simple transformer balun, and an ideal balun, clearly demonstrate the advantages of the hybrid balun in fully differential CMOS RF receivers. The simulated results of the receiver with the hybrid balun show 33 dB of conversion gain, 4.2 dB of noise figure with 20 kHz of 1/f noise corner frequency, and -17.5 dBm of IIP3 at a current consumption of 5 mA from 1.8 V supply.

• Journal of Broadcast Engineering
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• v.9 no.3
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• pp.225-235
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• 2004

In this paper, we propose a new stereoscopic video coding approach for heterogeneous consumer devices by exploiting the concept of spatio-temporal scalability. The proposed method uses MPEG-2 standard for coding the left or main sequence and an enhanced compatible coding scheme for predicting the P- and B-type of frames of the right or auxiliary sequence. The enhanced compatible coding scheme predicts matching block by interpolating both two forward and backward motion predicted macroblocks and disparity predicted macroblock. To provide flexible stereo video service, we define both a temporally scalable layer and a spatially scalable layer for each eye-view. The experimental results show the efficiency of proposed coding scheme by comparison with already known methods and the advantages of disparity estimation in terms of scalability overhead. According to the experimental results, we expect the proposed functionalities will play a key role in establishing highly flexible stereo video service for ubiquitous computing environment where devices and network connections are heterogeneous.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.601-606
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• 2008

When sharing real-time media in the ubiquitous computing environments, due to heterogeneous performance of devices, conflict to users' media service requirements might be occurred. To address the problems, there are extensive researches about media streaming QoS control schemes in the aspects of network or application. However, their deployment has met with difficulty because of critical reasons such as high development cost and system complexity. In this paper, in the level of media services, we propose a negotiation approach to offer improved quality of media services. The proposed approach Constructs video distribution group between producer and consumer services, which target to globally minimize the concession of users' quality requirements Consequently, users can be provided video services in the level of conformation to the users' expectation.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.286-291
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• 2008

Intelligence of collaborative environments starts from a trial to provide optimal services to with users based on real-time information about participants and environments of the collaboration itself. Up to now, we can collect information such as temperature, light, time, each participant's gestures, faces, voices, and locations by adopting ubiquitous computing technologies. However, since social relationship is intrinsic to collaborative activities, the relationships and roles among participants should be fully considered to provide optimal services. To do so, we have to integrate collected data from various sensors and extracted data about relationships and roles among participants as unified one context. Thus, this paper designs collaborative services filtered, by using the integrated data as a context, and introduces an implemented example, context-aware based interactive display service, called as smart meeting system (SMeet system).