• Smart Media Journal
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• v.8 no.2
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• pp.21-28
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• 2019

Recent research on energy harvesting wireless sensor networks focuses on the development of techniques to solve the limited energy resource problem and to extend the whole network life efficiently. Energy harvesting technology can increase the lifetime of a network, but data transmission becomes unavailable when it harvests energy from radio frequency, resulting longer network delay with respect to the increased time in energy harvesting. Therefore, building energy harvesting wireless sensor network should consider the possible network delay as well as the network lifetime problem. In this paper, we propose a new MAC protocol that minimizes end-to-end network delay by adjusting the data transmission time for a packet based on estimating the energy for data transmission along with the amount of traffic flowing into the network and harvested energy. For this goal, it engineers an energy management mechanism that adjusts the sleep time of the network by measuring energy harvesting time. In addition, with simulation results it shows that the proposed MAC protocol improves the performance in terms of energy consumption and end-to-end delay, compared to the existing MAC protocols.

• Smart Media Journal
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• v.8 no.1
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• pp.43-50
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• 2019

As numerous devices are connected through a wireless network, there exist many studies conducted to efficiently connect the devices. While earlier studies often use clustering for efficient device management, there is a load-intensive cluster node which may lead the entire network to be unstable. In order to solve this problem, we propose a scheduling model for centralized unequal chain clustering for efficient management of sensor nodes. For the cluster configuration, this study is based on the cluster head range and the distance to the base station(BS). The main vector projection technique is used to construct clustering with concentricity where the positions of the base stations are not the same. We utilize a multiple radio access interface, multiple-input multiple-output (MIMO), for data transmission. Experiments show that cluster head energy consumption is reduced and network lifetime is improved.

• Journal of Industrial Convergence
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• v.16 no.2
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• pp.1-14
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• 2018

The interconnectedness of all things is continuously expanding. For example, bluetooth low energy (BLE) beacons are wireless radio transmitters that can send an identifier to nearby receivers and trigger a number of applications, from proximity marketing to indoor location-based service. iBeacon technology which is one of the newest technologies in the smart tourism field, is reckoned as being very useful for travelers in enhancing the experience with visiting places. However, there is consequently not much existing research yet about the connection between iBeacon technology and tourism destination. Considering that, this study analyzes the adoption of iBeacon in tourism destination, this study examine the interrelationships and feedback structures of key factors in iBeacon adoption. To serve the purpose, this study used system dynamics approach to develop a model of iBeacon adoption in tourism destination. The analysis results showed that the concept of 'Social Influences' is one of the significant predictors for individual's intention behavior to accept iBeacon, and word of mouth (WOM), subjective norm, privacy concern, and perceived usefulness are key factors influencing the iBeacon adoption.

• Smart Media Journal
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• v.9 no.4
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• pp.60-65
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• 2020

The monopulse tracking algorithm can estimate the location of a partner station based on an RF (Radio Frequency) signal. The location of the partner station is estimated based on the monopulse ratio curve (MR-C), which is calculated based on the sum and difference signal patterns of an antenna. Therefore, the range in which the estimated location can be calculated with high accuracy increases in proportion to the linear region of MR-C. In this paper, we proposed a method to extend the linear region of the MR-C curve using the beamforming technique for the tracking antenna system using the active phased array antenna. Simulation results based on the same antenna system, it was confirmed that the linear region of MR-C was enlarged by about twice as much as the general case where the proposed method was not applied.

• Korean Journal of Computational Design and Engineering
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• v.20 no.2
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• pp.159-170
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• 2015

Radio-Frequency Identification (RFID) or Near Field Communication (NFC) technology has many advantages over other visual interfaces since it does not require line-of-sight alignment, can identify multiple tags simultaneously, and does not destroy the integrity of original objects. In addition, smart devices such as smartphone and smartpad have NFC/RFID readers which can provide mobile and natural interactions with digital and physical contents. Augmented reality has an excellent visual interaction capability with digital contents in a real environment by embedding digital contents into the physical world. In this paper, we propose a new approach to digital content interactions using RFID/NFC-based tangible interfaces in augmented reality environments that utilize invisible interfaces in addition to marker-based visual interfaces. By combining the advantages of invisible and visual interfaces, more intuitive interactions with digital contents can be provided, which can remove the difficulty of using typical AR paddles that are widely used in AR interactions. In particular, a semantic AR ontology is defined to provide more convenient interactions. Through the semantic ontology-based inferencing, physical querying and filtering are effectively supported. We will show the effectiveness and advantage of the proposed approach by demonstrating implementation results.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1857-1862
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• 2016

Human activity recognition using depth information is an emerging and challenging technology in computer vision due to its considerable attention by many practical applications such as smart home/office system, personal health care and 3D video games. This paper presents a novel framework of 3D human body detection, tracking and recognition from depth video sequences using spatiotemporal features and modified HMM. To detect human silhouette, raw depth data is examined to extract human silhouette by considering spatial continuity and constraints of human motion information. While, frame differentiation is used to track human movements. Features extraction mechanism consists of spatial depth shape features and temporal joints features are used to improve classification performance. Both of these features are fused together to recognize different activities using the modified hidden Markov model (M-HMM). The proposed approach is evaluated on two challenging depth video datasets. Moreover, our system has significant abilities to handle subject's body parts rotation and body parts missing which provide major contributions in human activity recognition.

• Information and Communications Magazine
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• v.26 no.1
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• pp.25-30
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• 2009

IT산업은 '97년 외환위기를 기점으로 고성장을 거듭하였고, 세계 10위권 규모의 경제 강국으로 성장하는데 있어 국내 산업의 대표적인 성장동력으로서 자리 매김하였다. 하지만, 최근 성장률이 예전만 못하다는 우려의 목소리와 함께 IT가 한 단계 더 업그레이드하기 위해서는 자신의 허물을 과감히 벗는 용기가 필요하다는 것이 일반적인 시각이다. 이러한 흐름속에서 기존 IT전략과 차별화된 New IT 발전방안을 수립하게 되었다. 지금까지의 IT전략이 IT 고도화 추진을 위한 IT 중심 발전 전략이었다면, New IT전략은 IT기반 융합산업, IT융합 신산업, Next IT산업 등3대 성장축간 시너지 창출이 가능한 IT로의 수렴과 확산이 핵심이라고 할 수 있다. IT기반 융합산업의 최종 목표는 전통산업과 IT가 만나 자동차, 조선, 의료, 국방, 건설, 섬유, 기계항공 등 7개 주력기간산업의 고부가가치화 및 초일류화를 우선 실현하는 것이다. IT융합 신산업의 최종 목표는 나노(NT), 바이오(BT), 인지기술(CT) 등 비(非)IT와 교감을 통하여 IT가 에너지, 환경, 건강 등 사회적 문제를 해결하고, 녹색성장 추진의 핵심인 5대 신산업을 창출하는데 있다. 5대 신산업으로는 Green IT산업, Welfare-Infra산업, 감성조명산업, 인지단말산업, THz응용산업 등을 꼽을 수 있다. Next IT산업은 기존 14대 IT 분야를 'ETRI 비전 2020' 등 미래 청사진을 바탕으로 장기적 관점에서 재설계한 것이며, 최종 목표는 TDX, 4M D램, CDMA, 와이브로, DMB, NoLA 등 IT 강국 계보를 이어갈 4G, 미래인터넷, Smart Radio, 실감미디어, 웹3.0, 투명전자소자 등 미래 유망 핵심원천기술을 확보하고, IT 경쟁력을 강화하는 것이다.

• Structural Engineering and Mechanics
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• v.17 no.3_4
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• pp.331-346
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• 2004

A new sensor system is proposed for measuring damage indexes. The damage index is a physical value that is well correlated to a critical damage in a device or a structure. The mechanism proposed here utilizes elastic buckling of a thin wire and does not require any external power supply for memorizing the index. The mechanisms to detect peak strain, peak displacement, peak acceleration and cumulative deformation as examples of damage indexes are presented. Furthermore, passive and active wireless data retrieval mechanisms using electromagnetic induction are proposed. The passive wireless system is achieved by forming a closed LC circuit to oscillate at its natural frequency. The active wireless sensor can transmit the data much further than the passive system at the sacrifice of slightly complicated electric circuit for the sensor. For wireless data retrieval, no wire is needed for the sensor to supply electrical power. For the active system, electrical power is supplied to the sensor by radio waves emitted from the retrieval system. Thus, external power supply is only needed for the retrieval system when the retrieval becomes necessary. Theoretical and experimental studies to show excellent performance of the proposed sensor are presented. Finally, a prototype damage index sensor installed into a 7 storey base-isolated building is explained.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.212-220
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• 2014

The current cellular communications are optimized for low mobility users, meaning that their performance is degraded at high speed. Therefore, passengers in a high-speed train experience very poor radio link quality due to the significantly large number of simultaneous handovers. In addition, wireless data traffic is expanding exponentially in trains, subways and buses due to the widespread use of smartphones and mobile devices. To solve the inherent problem of cellular communication networks and meet the growing traffic demand, this paper proposes the mobile hotspot network of a millimeter-wave communication system as a mobile wireless backhaul. This paper describes the physical layer design of uplink and downlink in the proposed system, and the performances of uplink and downlink are evaluated under Rician fading channel conditions. The implemented baseband prototype of the proposed millimeter-wave communication modem is presented. This system can provide a Gbps data rate service in high-speed trains carrying hundreds of wireless Internet users.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.4
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• pp.9-14
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• 2008

Ubiquitous implementation of indoor location-based technology is recognized that one of the important elements of the technology. Specifically, the hospital management of patients, the silver-town management, the implementation of the smart home for the indoors rather than outdoors in a range of broadband users for location-aware technology is needed. This paper in wireless devices with an indoor location awareness shows about the system's technical design and implementation. Location-based technology for wireless LAN users aware of the strength of radio signals (Received Signal Strength Indication, RSSI) using trilateration. Topographic mapping system will be implemented wireless devices and servers, Access Point (AP), which is the system's development and testing throughout the physical environment to determine the potential for real-life applications.