• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권1호
• /
• pp.79-95
• /
• 2016

In order to improve the Quality-of-Service (QoS) of latency sensitive applications in next-generation cellular networks, multi-path is adopted to transmit packet stream in real-time to achieve high-quality video transmission in heterogeneous wireless networks. However, multi-path also introduces two important challenges: out-of-order issue and reordering delay. In this paper, we propose a new architecture based on Software Defined Network (SDN) for flow aggregation and flow splitting, and then design a Multiple Access Radio Scheduling (MARS) scheme based on relative Round-Trip Time (RTT) measurement. The QoS metrics including end-to-end delay, throughput and the packet out-of-order problem at the receiver have been investigated using the extensive simulation experiments. The performance results show that this SDN architecture coupled with the proposed MARS scheme can reduce the end-to-end delay and the reordering delay time caused by packet out-of-order as well as achieve a better throughput than the existing SMOS and Round-Robin algorithms.

• 세라미스트
• /
• 제23권1호
• /
• pp.54-88
• /
• 2020

Global effort has resulted in tremendous progress with energy harvesters that extract mechanical energy from ambient sources, convert it to electrical energy, and use it for systems such as wrist watches, mobile electronic devices, wireless sensor nodes, health monitoring, and biosensors. However, harvesting a single energy source only still pauses a great challenge in driving sustainable and maintenance-free monitoring and sensing devices. Over the last few years, research on high-performance mechanical energy harvesters at the micro and nanoscale has been directed toward the development of hybrid devices that either aim to harvest mechanical energy in addition to other types of energies simultaneously or to exploit multiple mechanisms to more effectively harvest mechanical energy. Herein, we appraise the rational designs for multiple energy harvesting, specifically state-of-the-art hybrid mechanical energy harvesters that employ multiple piezoelectric and triboelectric mechanisms to efficiently harvest mechanical energy. We identify the critical material parameters and device design criteria that lead to high-performance hybrid mechanical energy harvesters. Finally, we address the future perspectives and remaining challenges in the field.

• International journal of advanced smart convergence
• /
• 제5권3호
• /
• pp.16-26
• /
• 2016

This proposed project is about a bicycle anti theft devised system which helps people protect the bicycle from theft and helps to track the stolen bicycle's location using a smart phone. Safety bike uses two main devices to keep the bicycle secured, the vibration sensor and GPS sensor. The purpose of this project is to put all these small devices into one well connected system which will help the bicycle owner have more control over the security of his own bicycle. The whole system can be divided into two main parts. The first part is about the hardware development whereby all electronics components are connected via the circuit design using wire wrapping technique. This hardware part includes, a vibrations sensor, a GPS receiver, a toggle switch, LED light, Bluetooth and a buzzer. Wireless Bluetooth signals are used as the means of communication between the smartphone and the microcontroller. The second part is the software part which is being to program and control the whole system. The program is written using MikroBasic, a full-featured Basic compiler for microcontroller based systems. In conclusion, this system is designed to enable user to have control in securing his/her bicycle also being able to find and locate it at any time using GPS receiver and mobile android application.

• 한국인터넷방송통신학회논문지
• /
• 제14권5호
• /
• pp.61-65
• /
• 2014

본 논문에서는 다중 경로 페이딩 및 주파수 선택적 페이딩을 겪는 채널을 회피하기 위한 방안을 정의하였다. 기존의 기법에서, 페이딩 현상을 해결하기 위해 다중 입출력 안테나(MIMO) 혹은 직교 주파수 분할 다중(OFDM) 기법을 적용하였으나 하드웨어의 제약으로 인해 실제적인 구현이 어렵다. 따라서 본 논문에서는 협력 스펙트럼 감지 기법을 통해 얻은 우수한 채널 정보를 송신단에게 제공하는 기법을 제안한다. 송신단에서는 수집된 정보를 바탕으로 페이딩을 겪는 채널에 대한 회피를 구현할 수 있으며 수신단에서 복호의 성능을 향상 시킬 수 있다. 마지막으로, 비트 오류율을 통해 페이딩을 겪는 채널과 제안된 프로토콜의 성능을 비교, 분석한다.

• 대한안전경영과학회지
• /
• 제9권6호
• /
• pp.155-162
• /
• 2007

Recently, retail store automation appliance market is changed with traditional POS systems techniques and RFID, radio POS system, and self checkout system, etc. in the foreign advanced distribution industry. Retailers and consumers require convenient POS system which can provide more functions and fast service. These requests bring to rapid evolution of various H/W and S/W corresponding with POS system. In this study with the POS systems and the RFID technology we develop core technology of movable u-POS system based on RFID that can use in large store. So we propose u-Cart system that can alternate the current shopping cart and POS terminal and that provide value added services to customer. As the result we present the configuration of u-Cart terminal device(WMDT : Wireless Mobile Data Terminal) including RFID reader module that can provide various information to consumer and some convenient client applications that are running in WMDT and u-POS administration service module.

• 디지털산업정보학회논문지
• /
• 제10권1호
• /
• pp.73-79
• /
• 2014

In this study, the unmanned vehicle to develop a preliminary step, we were facilities for Automated Guided Vehicle (AGV) simulator is designed and implemented. Industry is increasingly the more advanced automation and management systems need to be efficient. These studies are at least 24-hour continuous unmanned vehicles and personnel can result in reduction of labor costs. In addition, safety accidents can be minimized in the industry as an effect of intelligent AGV is essential. This study is the initial step for the development of AGV. manufactured simulator to Simulation and drives the performance of the system is evaluated. The configuration of the simulator, ultrasonic sensors, infrared sensors, and using the obstacle were to follow a given path. In addition, two-way communication between the host computer and the main processor that was. communication method that IEE802.11 meets the standard is applied to high-speed wireless LAN systems, each of the sensor information is calculated. AGV having a drive shaft 4 of the four wheels are respectively independent structure. AGV's main processor is driven using a high-performance DSP, and the controller controls the steering device of the load could be significantly reduced.

• 한국게임학회 논문지
• /
• 제11권6호
• /
• pp.95-102
• /
• 2011

현재 와이파이가 지원되는 스마트폰 시장이 급격히 증가하면서 스마트 폰을 기반으로 하는 네트워크 콘텐츠 가 빠르게 보급되고 있다. 하지만, 아직까지 와이파이가 지원되지 않거나 블루투스 환경만을 제공하는 피처폰이나 기타 멀티미디어 기기 등에서는 네트워크 콘텐츠를 제공하기 힘든 환경이다. 본 논문에서는 블루투스, 와이파이 등의 기술보다도 저전력, 저가격, 사용의 용이성, 다채널, 브로드캐스팅을 지원하는 지그비 기술을 이용하였다. 근거리 네트워크 게임에 지그비 기술을 이용함으로써 다양한 형태의 네트워크 게임을 개발할 수 있을 것이다. 또한, 이를 이용한 다양한 무선 네트워크 컨텐츠의 개발을 기대할 수 있을 것이다.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2013년도 추계학술대회
• /
• pp.1048-1050
• /
• 2013

모바일 기기와 스마트폰은 급속하게 중앙의 컴퓨터와 통신 네트워크 기기로 변화하고 있다. 최근에는 스마트폰은 프로그램이 가능하며 가속도, 전자나침판, 자이로스코프, GPS, 마이크, 카메라와 같은 저가의 고성능 내장형 센서들과 함께 출시되고 있다. 본 논문에서는 무선 가스 센싱 서비스 구조를 분석하고 스마트폰과 웹 서버를 이용한 가스 센서 모니터링 서비스를 개발한다.

• 정보처리학회논문지C
• /
• 제16C권1호
• /
• pp.109-116
• /
• 2009

유비쿼터스 컴퓨팅 기술을 기반으로 주변 상황을 인식하고 그에 따른 상황인지 서비스를 실현하기 위한 많은 연구가 진행되고 있다. u-City에서는 도시의 곳곳의 센서 등을 통해 상황 정보가 수집되고, 개인들은 자신의 모바일기기와 도시의 정보 통신 인프라를 통하여 상황인지 서비스를 제공 받게 된다. 본 논문에서는 u-City의 네트워크에 연결된 센서나 디바이스에서의 정보를 구조화하는데 유용하고 상호 관계성 및 부분적인 상황의 정보를 표현할 수 있는 OWL(Web Ontology Language)을 사용한 온톨로지를 설계하고, 수집된 상황정보와 사용자의 의도를 기반으로 서비스를 추론하는 맞춤형 u-City 서비스 제공을 위한 상황인지 추론 시스템을 제안한다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2009년도 제38회 동계학술대회 초록집
• /
• pp.49-49
• /
• 2010

Nanopiezotronics is an emerging area of nanotechnology with a variety of applications that include piezoelectric field-effect transistors and diodes, self-powered nanogenerators and biosystems, and wireless nano/biosensors. By exploiting coupled piezoelectric and semiconducting characteristics, it is possible for nanowires, nanobelts, or nanorods to generate rectifying current and potential under external mechanical energies such as body movement (handling, winding, pushing, and bending) and muscle stretching, vibrations (acoustic and ultrasonic waves), and hydraulic forces (body fluid and blood flow). Fully transparent, flexible (TF) nanogenerators that are operated by external mechanical forces will be presented. By controlling the density of the seed layer for ZnO nanorod growth, transparent ZnO nanorod arrays were grown on ITO/PES films, and a TF conductive electrode was stacked on the ZnO nanorods. The resulting integrated TF nanodevice (having transparency exceeding 70 %) generated a noticeable current when it was pushed by application of an external load. The output current density was clearly dependent on the force applied. Furthermore, the output current density depended strongly on the morphology and the work function of the top electrode. ZnO nanorod-based nanogenerators with a PdAu, ITO, CNT, and graphene top electrodes gave output current densities of approximately $1-10\;uA/cm^2$ at a load of 0.9 kgf. Our results suggest that our TF nanogenerators are suitable for self-powered TF device applications such as flexible self-powered touch sensors, wearable artificial skins, fully rollable display mobile devices, and battery supplements for wearable cellular phones.