• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.832-835
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• 2008

An information-oriented basis in today's society has been changing fast, and the desire for connectivity has caused an exponential growth in wireless communication and sensor network. Sensor networks using RFID, in particular, have led this trend due to the increasing exchange of data in Ubiquitous such as the home RF, access control system, U-Healthcare, and Logistics information Systems. Also, the RFID when it applies a technique, is able to raise the stability of shipping as controling the mobile course and an entrance and exit of the crews an well as previously preventing an accident from shipping. In this paper, we designed and implemented personnel control system using UHF-RFID in vessels which shows through host PC reading and writing tag.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.12
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• pp.1328-1336
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• 2012

Compared to terrestrial RF communications, underwater acoustic communications have several limitations such as limited bandwidth, high level of fading effects, and a large underwater propagation delay. In this paper, in order to tackle those limitations of underwater communications and to make it possible to form a large underwater monitoring systems, we propose a hierarchical underwater network architecture, which consists of underwater sensors, clusterheads, underwater/surface sink nodes, autonomous underwater vehicles (AUVs). In the proposed architecture, for the maximization of packet delivery ratio and the minimization of underwater sensor's energy consumption, a hybrid routing protocol is used. More specifically, cluster members use Tree based routing to transmit sensing data to clusterheads. AUVs on optimal trajectory movements collect the aggregated data from clusterhead and finally forward the data to the sink node. Also, in order to minimize the maximum travel distance of AUVs, an Integer Linear Programming based algorithm is employed. Performance analysis through simulations shows that the proposed architecture can achieve a higher data delivery ratio and lower energy consumption than existing routing schemes such as gradient based routing and geographical forwarding. Start after striking space key 2 times.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.11
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• pp.2119-2124
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• 2008

An information-oriented basis in today's society has been changing fast, and the desire for connectivity has caused an exponential growth in wireless communication and sensor network. Sensor networks using RFID, in particular, have led this trend due to the increasing exchange of data in Ubiquitous such as the home RF, access control system, U-Healthcare, and Logistics information Systems. Also, the RFID when it applies a technique, is able to raise the stability of shipping as controling the mobile course and an entrance and exit of the crews an well as previously preventing an accident from shipping. In this paper, we designed and implemented personnel control system using UHF-RFID in vessels which shows through host PC reading and writing tag.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.661-664
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• 2009

Recently, intelligent surveillance camera systems are needed popularly. However, current researches are focussed on improvement of a single module rather than implementation of an integrated system. In this paper, we implemented a moving wireless surveillance camera system which is composed of face detection, and using motion sensor. In our implementation, we used a camera module from SHARP, a pair of wireless video transmission module from ECOM, body of moving robot used for A4WD1 Combo kit for RC, a pair of ZigBee RF wireless transmission module from ROBOBLOCK, and a motion sensor module (AMN14111) from PANASONIC. We used OpenCV library for face dection and MFC for implement software. We identified real-time operations of face detection, PTT control, and motion sensor detecton. Thus, the implemented system will be useful for the applications of remote control, human detection, and using motion sensor.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.50-54
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• 2015

In this paper, we report on a high performance 94 GHz MMIC mixer module using 0.1-um metamorphic high electron mobility transistors (MHEMTs). A modified resistive mixer with a RF amplifier was proposed in this work for low conversion loss and high LO-RF isolation. The MMIC mixer module was fabricated using a MMIC chip and CPW-waveguide transitions. The fabricated mixer chip and module showed a low conversion loss of 6.3 dB and 9.5 dB, and LO-RF isolations of 24.8 and 30.4 dB at 94 GHz, respectively. This results are superior to those of previously W-band (75-110 GHz) MMIC mixers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.245-248
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• 2012

In this paper, the optimized growing conditions of PZT thin films on low temperature co-fired ceramics (LTCC) substrates are studied. The LTCC technology is an emerging one in the fields of mesoscale (from 10 um to several hundred um) sensor and actuator against silicon based technology due to low cost, high yield, easy manufacturing of 3 dimensional structure, etc. The LTCC substrates with thickness of 400 um are fabricated by laminating 100 um green sheets using commercial power (NEG, MLS 22C). The Pt/Ti bottom electrodes are deposited on the LTCC substrates, then the growing conditions of PZT thin films using rf magnetron sputtering method are studied. The growing conditions are tested under various rf power and gas ratio of oxygen to argon. And the crystallization and ingredient of PZT films are analyzed by X-ray diffraction method (XRD) and energy dispersive spectroscopy (EDS). The optimized growing conditions of PZT thin films are rf power of 125W, Ar/O2 gas ratio of 15:5.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1912-1921
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• 2015

In this paper, we introduce a testbed for testing the RF energy transfer technology in the Internet of Things (IoT) environment, and provide experimental results obtained by using the testbed. The IoT environment considered in this paper consists of a power beacon, which is able to wirelessly transfers energy via microwave, and multiple sensor nodes, which makes use of the energy received from the power beacon. We have implemented the testbed to experiment the RF energy transfer in such IoT environment. We have used off-the-shelf hardware components to build the testbed and have made the tesbed controlled by software so that various energy and data transmission protocol experiments can easily be conducted. We also provide experimental results and discuss the future research direction.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.508-511
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• 2005

In the near future various new services will be created by using ubiquitous computing and ubiquitous network. Especially u-LBS(Ubiquitous Location Based Services) is recognized as one of the most important services. U-LBS is based on the data created by recognizing objects including both human and matters at any time and anywhere. Many researches related with object locating method by using RF are in the process of studying However there are few researches on the location of objects. In this paper we propose the recognition method of the location of objects by using RF and USN technology. In detail, the strength of RF signal is used to recognize the location of objects. Also we discuss about the future work to enhance the recognition rate of location by using a number of conditions including the weather, temperature etc. And Genetic Algorithm is used to get the optimal parameters with which we can get the more exact recognition rate of location.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06c
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• pp.138-143
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• 2008

RFID 기술은 기존의 바코드 기술보다 발전된 무선의 비접촉 인식 기술로서, 유비쿼터스 컴퓨팅의 핵심기술로 간주되고 있다. RFID 태그는 기존의 단순한 사물의 인식 기능 중심에서 사물의 상태 및 환경 정보를 감지할 수 있는 센서 태그로의 발전으로 물류 프로세스의 양적, 질적 향상을 도모할 수 있게 되었다. 센서 태그는 환경 정보를 센싱하기 위하여 배터리를 내장하고 있으며, RF Transceiver의 내장 유무에 따라 자체적으로 신호를 보낼 수 있는 active 센서 태그와 리더로부터의 신호를 사용하는 semi-passive 센서 태그로 구분된다. Semi-passive 센서 태그는 배터리를 부착함으로써 passive 태그에 비해 인식률과 인식거리가 향상되었고 active 태그에 비해 단가가 매우 저렴하여 센서 태그가 부착된 물품의 상태를 모니터링하고 환경을 감시하는 다양한 응용에 사용될 수 있다. 이러한 응용의 요구에 따라 Edge Manager는 기존의 passive 태그는 물론 센서 태그를 지원함으로써 상위 응용에게 정제된 결과를 전달할 필요성이 있다. 본 논문에서는 특히 semi-passive 센서 태그를 지원하는 Edge Manager의 설계를 위하여, 센서를 사용한 또 다른 활용 분야인 센서 네트워크에서의 질의 유형을 분석하고, semi-passive 센서 태그의 특징을 고려한 요구사항을 분석한다. Semi-passive 센서 태그는 센서 네트워크의 센서 노드와는 달리 태그 레벨에서 필터링과 병합을 수행할 수 없으므로 Edge Manager에서 이러한 기능이 제공되어야 한다. 본 논문에서는 Edge Manager에서의 센서 태그 데이터에 대한 질의를 위한 방법으로 EPCglobal ALE 표준명세의 ECSpec을 확장하는 방법을 제안하고, 센서 태그 데이터의 특성을 고려한 필터링 기법과 병합(aggregation) 기법을 적용한 질의 처리가 가능한 Edge Manager의 구조를 제시한다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.499-502
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• 2000

In this study, $\alpha$-Fe$_2$O$_3$thin films were deposited on $Al_2$O$_3$substrate by RF magnetron sputtering method from a $\alpha$-Fe$_2$O$_3$target(99.9%). The sputtering atmosphere was Ar and 80%Ar:20%O$_2$mixture in a total gas pressure of 1~3mTorr. As-deposited $\alpha$-Fe$_2$O$_3$thin films were heated to 300, 400, 500, $600^{\circ}C$ for 5hr in oxygen atmosphere. The structure and the morphology of $\alpha$-Fe$_2$O$_3$thin films were examined by scanning Electron microscopy(SEM) and the crystal structure was analyzed by X-Ray Diffractometer(XRD). The microstructure of the annealed $\alpha$-Fe$_2$O$_3$films exhibits rather gross particle and the grain size was less than 100nm. Since the grain size was very small, the gas sensitivity was expected to be improved.