• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.767-768
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• 2006

In this paper we propose a new routing protocol, which takes residue energy of nodes into account in order to prevent node failures resulting from energy shortage. Our routing protocol examines the smallest value of node residue energy ($E_m$) from each of all possible routing paths and selects the path which has the largest value of $E_m$. We prove, through simulation, that our routing protocol extends the lifetime of nodes which have limited amount of energy, reducing chances of path replacement. It is also shown that our proposed protocol helps alleviate network performance degradation.

• Journal of information and communication convergence engineering
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• v.9 no.1
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• pp.16-20
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• 2011

In this paper, we designed and implemented an internal multi-band folded monopole antenna for mobile handset. The proposed antenna covers Global System for Mobile Communications (GSM900: 880~960 MHz), Digital Communications System (DCS: 1710~1880 MHz), US-Personal Communications Service (US-PCS: 1850~1990 MHz), Bluetooth(2400~2484 MHz), WiMAX(3400~3600 MHz), and Wireless Local Area Network (WLAN: 5150~5350 MHz, 5725~5875 MHz) band for Voltage Standing Wave Ratio $(VSWR)\;{\le}\; 3$. The measured peak gains of the implemented antenna are -1.78dBi at 920MHz, 2.72dBi at 1795MHz, 2.25dBi at 1920MHz, 2.34dBi at 2442MHz, 2.11 dBi at 3550MHz, and 2.04 dBi at 5250MHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.2
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• pp.136-141
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• 2007

To produce eco marine products which is taking interests recently, the necessity of aquafarm tracing system is being emphasized. Considering the particularity of aquafarm, wireless communication environment is essential in order to manage aquafarm efficiently. The terminal which automatically collecting the environmental information and transferring it to server needs specified functions; input-output the information conveniently and search it visually. In this paper, we design specified terminal and its functions to monitor the environmental information at aquafarm.

• Archives of design research
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• v.17 no.1
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• pp.49-62
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• 2004

Due to the recent surge of wireless Internet and concurrent development of the end user terminal devices having standardized graphical user interface(GUI) and unified operation mechanism for better interactivity in information representation and ease of use, various efforts on the improvement of GUI is widely recognized as one of the key factors that will usher in the next stages of the wireless Internet for the users. Especially, improved usability along with unique visual effect are considered to be the key elements for GUI considering the rapid improvement of the resolution and color on the end user handset devices; thus, the study and research on the subject of GUI is expected to increase along with the wireless Internet using smart phones. User interface of the wires Internet end user handsets will have a definite and significant effect on the user interaction as well as productivity. Domestically, wireless Internet service providers and GUI design companies are making various efforts in producing a common GUI models for standardized operation scheme and improved graphical display capabilities of the hand phones, PDAs and smart phones. In the study, Nokia 3650 model and Microsoft Orange SPV model were chosen as test devices for usability comparison and data collection to collect directional benchmark data in developing next generation smart phone user interface integrating PDAs and phones. The mail purpose of this study is to achieve the most efficient user accessibility to WAP menu through intensive focus on developing WIPI WAP menu having most effective usability for the users in their twenties and thirties. The result of this study can also be used as the base research materials for WAP service development, VM browser development and PDA browser development. The result of this study along with the evaluation model is expected to provide effective analysis materials on the subject of user interface to the developers of the wireless Internet user devices, GUI designers and service planners while short listing key factors to consider in developing smart phones therefore serving as the GUI guideline of WIPI phones.

• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.11-18
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• 2009

As a marine leisure industry has being developed and demands for leisure culture have rapidly increased, the needs for services offering marine safety and related information are growing. Accordingly, in the study I developed the contents providing server to support this with ENC agent who presents geographical information of digitalized Electronic Nautical Chart satisfying with the standard(S-57) by International Hydrographic Organization and a web searching agent who builds a database by collecting marine-related information in order to provide a variety of realtime information such as weather, fishing and news. In addition, I designed and embodied network based mobile contents which can be presented on a WIPI(Wireless Internet Platform for Interoperability) based portable handset by receiving an ENC and other processed information from server. With the results produced by such experiments, I measured a compressibility corresponding to a image compression format of electronic nautical chart transmitted and analyzed the correlation between increase in packets of requested information and the cost.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.621-627
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• 2008

This paper presents a compact and miniaturized power detector utilizing low temperature co-fired ceramics(LTCC) technology for the application in wireless handset system to monitor the transmitting power at the frequency of 824-849MHz. The proposed power detector is composed of detector diode, lumped components for matching network, and LTCC stripline coupler based on LTCC substrate technology. A 20dB LTCC stripline direction coupler is designed and implemented with many bending section in order to reduce the practically occupied area for miniaturization. A zero bias schottky diode is adopted for detector design because of its high speed operation with minimized loss. The measured performances of fabricated detector agree well with the predicted results with a good linearity within the effective input RF power range.

• ETRI Journal
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• v.35 no.1
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• pp.51-57
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• 2013

In this paper, a small internal antenna for a mobile handset is presented using multiband, wideband, and high-isolation multiple-input multiple-output techniques. The proposed antenna consists of three planar inverted-F antennas (PIFAs) that operate in the global system for mobile communication (GSM900), the digital communication system (DCS), the personal communication system (PCS), the universal mobile telecommunication system (UMTS), and wireless local area network (WLAN) bands with a physical size of $40mm{\times}10mm{\times}10mm$. A resonator attached to the folded PIFA creates dual resonances, achieving a wide bandwidth of approximately 460 MHz, covering the DCS, PCS, and UMTS bands; a meander shorting line is used to improve impedance matching. Additionally, a modified neutralization link is embedded between diversity antennas to enhance isolation, which results in a 6-dB improvement in the isolation and less than 0.1 in the envelope correlation coefficient evaluated from the far-field radiation patterns. Simulation and measurements demonstrate very similar results for S-parameters and radiation patterns. Peak gains show 3.73 dBi, 3.77 dBi, 3.28 dBi, 2.15 dBi, and 5.86 dBi, and antenna efficiencies show 56.15%, 72.15%, 68.59%, 52.92%, and 82.93% for GSM900, DCS, PCS, UMTS, and WLAN bands, respectively.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.379-381
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• 2006

모바일 표준 플랫폼 WIPI(Wireless Internet Platform for interoperability)는 모바일 단말기에 탑재되어 응용프로그램을 실행할 수 있는 실행환경을 제공하는 국내 모바일 표준 플랫폼이다. 2002년부터 개발이 시작되어 현재 WIPI 2.0 규격을 탑재한 모바일 단말기가 출시된 상황이다. WIPI 2.0 규격은 PC연결 등의 표준 입출력, 폰카메라, 위치알림 기능, 보안통신 등의 서비스까지 규격화하고 있으며, 차기 버전에서는 휴대폰은 물론 휴대인터넷이나 위성 디지털멀티미디어방송(DMB) 단말기 플랫폼으로의 확장도 모색되는 등 발전가능성이 크다. 그러나 WIPI가 고려되지 않고 설계된 현재의 운영체제상에서 구현된 표준 플랫폼은 설계상 제한이 있으며, 미들웨어의 성격이 강하기 때문에 특정하드웨어와 운영체제에서의 WIPI 지원여부에 따라 응용 분야에 제약이 가해진다. 본 논문에서는 모바일 디바이스를 위한 연구개발을 목적으로 개발된 오픈소스기반 운영체제인 OpenOS의 커널수준에서 WIPI 표준 플랫폼의 HAL(Handset Adaptation Layer)과 WIPI-C 필수 API를 구현하여 성능의 개선과 표준 플랫폼을 위한 운영체제로의 발전 및 활용 가능성을 제시한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.203-206
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• 2005

차량 진단 기능이 탑재된 원격 서버, 제어 신호 중계 기능을 가진 휴대폰용 어플리케이션, 그리고 신호 변환을 위한 converting 보드를 사용하여 기존의 차량진단기(scanner)와 동일한 기능을 가지는 원격차량진단 시스템을 제안한다. 원격 서버에서 직접 차량 진단 기능을 수행함으로써 진단 이력에 대한 자동 관리가 가능하며 다양한 부가 서비스를 연계하여 제공할 수 있다. 또한 신규 차종에 대하여 원격 서버 프로그램의 변경으로 대응이 가능하므로 기존 방식처럼 신규 차종에 대한 개별 upgrade가 필요 없다. 제안한 방식은 저가의 진단 시스템 구축이 가능하므로 영업소에서만 사용되던 차량 진단기를 개별 사용자가 사용할 수 있게 해준다. 또한 bluetooth의 Serial Port Profile을 기반으로 휴대전화기와 converting 보드간의 선을 제거함으로써 사용자가 간단하게 진단 어플리케이션이 탑재된 bluetooth handset에서 진단을 할 수 있다. 실험을 통하여 제안한 방식의 실제 환경에서 잘 동작함을 검증하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.3
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• pp.266-284
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• 2009

The challenges of rapidly growing numbers of mobile nodes in IPv6-based networks are being faced by mobile computing researchers worldwide. Recently, IETF has standardized Mobile IPv6 and Fast Handover for Mobile IPv6(FMIPv6) for supporting IPv6 mobility. Even though existing literatures have asserted that FMIPv6 generally improves MIPv6 in terms of handover speed, they did not carefully consider the details of the whole handover procedures. Therefore, in conventional protocols, the handover process reveals numerous problems manifested by a time-consuming network layer based movement detection and latency in configuring a new care of address with confirmation. In this article, we study the impact of the address configuration and confirmation procedure on the IP handover latency. To mitigate such effects, we propose a new scheme which can reduce the latency taken by the movement detection, address configuration and confirmation from the whole handover latency. Furthermore, a mathematical analysis is provided to show the benefits of our scheme. In the analysis, various parameters are used to compare our scheme with the current procedures, while our approach is focused on the reduction of handover latency. Finally, we demonstrate total handover scenarios for the proposed techniques and discussed the major factors which contribute to the handover latency.