• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.4
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• pp.366-372
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• 2002

A wideband stacked patch antenna fed by an L-strip feeder is studied experimentally. The objective of this paper is to design small wideband antenna for PCS and IMT-2000 service. Experimental results confirm that an impedance bandwidth(VSWR$\leq$2) of 704.7 MHz(35.95 %) is achieved at PCS and IMT-2000 frequency band. The studied antenna can be designed easily for extension of away because it has simple structure.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.336-339
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• 2003

본 논문에서는 운전중인 주상 변압기의 상태 진단을 위하여 이동통신망의 SMS(Short Message Service)방식을 적용함으로써 진단 자료 전송시 무손실로 전달할 수 있는 기법에 관하여 연구한다. 최소한의 데이터전송으로 최적의 진단을 할 수 있도록 무선통신에 적합한 알고리즘 및 프로토콜을 설계한다. 주상변압기의 절연유 온도와 부하전류의 가변 실험을 통하여 데이터를 취득한다. 센서의 자료 취득부에서는 SMS 문자서비스를 이용하여 자료전달에 최적화가 되도록 센서 출력 결과의 필터링을 수행한다. 이러한 진단기법은 서버 1대에서 많은 수의 변압기를 관리 제어, 모니터링이 가능하며 변전기기 이외에 다른 모든 기기에 적용이 가능하다.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.414-417
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• 2003

In this paper, a performance of Bluetooth piconet is analyzed. Average cycle time, average waiting time, average transfer delay and average queue length are used for measure of performance (MOP). Simple round robin (RR) scheduling policy with exhaustive service is used for the analysis. Packet loss is considered because of noise environments of wireless communication. Numerical results have been presented. Simulation is performed to validate the correctness of analysis.y and its maximum operating frequency is 800MHz.

• Journal of the Korea Society of Computer and Information
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• v.22 no.8
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• pp.55-61
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• 2017

Cloud computing is cost-effective in terms of system configuration and maintenance and does not require special IT skills for management. Also, cloud computing provides an access control setting where SSO is adopted to secure user convenience and availability. As the SSO user authentication structure of cloud computing is exposed to quite a few external security threats in wire/wireless network integrated service environment, researchers explore technologies drawing on distributed SSO agents. Yet, although the cloud computing access control using the distributed SSO agents enhances security, it impacts on the availability of services. That is, if any single agent responsible for providing the authentication information fails to offer normal services, the cloud computing services become unavailable. To rectify the environment compromising the availability of cloud computing services, and to protect resources, the current paper proposes a security policy that controls the authority to access the resources for cloud computing services by applying the authentication policy of user authentication agents. The proposed system with its policy of the authority to access the resources ensures seamless and secure cloud computing services for users.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.10
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• pp.1022-1028
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• 2006

A portable ECG sensor module and monitoring system which has the powerline noise reduction and the baseline wander removal is proposed. A small-szie ECG sensor H/W module with the 8-bits microprocessor is implemented. The ECG waveform can be inspected anytime with PDA in real time, and transmitted to the PC through wireless LAN. Portable ECG system can offer the environment that give the lasting medical service to the elderly and the long-time hospitalized patients at the wanted place, and the system can be attached to the chair, wheel chair, treadmill, elderly walker and used to monitor the health condition of man

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.267-275
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• 2007

In this paper, we designed and implemented DCS terminal remote monitoring middleware for real-time auditor and management terminal status signal with relay and fuse status at power management room. The middleware consist of four component as event analyzer, event manager, service manager and user interface. We expected economic effects extend relay life-time that pre-detected errors and prevented relay fault.

• Management & Information Systems Review
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• v.21
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• pp.155-168
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• 2007

In the ubiquitous which is rapidly developing with ultra speed thes days, constructing the u-Campus which is using the sensor-network as its base is keep developing. Also, any information related equipments like PC and mobile, computing is possible whenever and wherever you want and due to the development of the wireless network, the service environment is continually developing. In this article, I'd like to suggest the u-Campus which is very suitable to the user's environment which had used application of mobile. In u-Campus, various techniques are adopted and applied along with development of info-communication related technidques. Especially, the new type of campus which is constructed by adopting the ubiquitous computing net-work technique to the campus of university is the u-Campus. In this article, by suggesting u-Yuhan designing methods, more effective and advanced school activities of students to make possible.

• Journal of the Korean Solar Energy Society
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• v.28 no.6
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• pp.58-63
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• 2008

It is essential to investigate the structure and the main characteristic of Home USN (Ubiquitous Sensor Network) technologies in built ubiquitous environment while designing bio-sensors. For this study, Thermistor elements and Thermopile black body have been selected to implement ubiquitous technologies for bio-sensors and wireless network such as WiBro has been used to transfer sensing data to the BSN (Bio-Sensor Network) gateway. It is certain that efficiency of ubiquitous space design is improved if main components of each specific sensor network are analyzed precisely in digital way and corresponding communication modules are prepared accordingly. Ubiquitous technology, in conclusion, has to be applied not only with systematical mechanism or electronic setting but in human-centered atmosphere as well, keeping with deep consideration for bio-housing service factors in eco-friendly surrounding.

• Proceedings of the IEEK Conference
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• summer
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• pp.185-188
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• 2004

Sufficient bandwidth that can support multimedia service has to be provided in the next generation wireless communication system. In this paper, the effective handoff scheme considering the position of mobile terminal is proposed. In addition, the dynamic channel allocation scheme is proposed. The shared channel in this algorithm can reduce more the blocking probability and the dropping probability. The proposed algorithms are simulated by SMPL library in C language. The simulation results show that the blocking probability and the dropping probability of the call can be reduced up to $60\%\;and\;10\%$ using the proposed algorithms, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.117-120
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• 2002

Bluetooth uses baseband of 2.4G ISM and composes radio Ad Hoc network based on Ad Hoc wireless connectivity which it used low power and low complexity solution. Bluetooth designed as can play detect, connect, discover service by surrounding other device even if users do not get acquainted all to Bluetooth. This paper operate wish to recognize mobility to routing algorithm how communication method and radio network in Bluetooth.