• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.645-648
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• 2004

In this paper, we drive a theoretical performance of complementary code keying (CCK) codes on additive white Gaussian noise (AWGN) channel. The CCK codes can be demodulated by the optimal maximum likelihood decoding method and sub-optimal correlation magnitude decoding algorithm. We calculate the bit error rate (BER) and symbol or codeword error rate (SER) of the CCK codes using the above mentioned two decoding algorithms. To derive the error performance, we use the weigh distributions and cross-correlation distributions of CCK codes.

• Journal of electromagnetic engineering and science
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• v.4 no.3
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• pp.124-127
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• 2004

A novel printed inverted-F antenna for dual-band WLAN is presented. The proposed design is based on the folded quarter-wave antennas, which have a conductor plate having two arms. An extremely thin prototype antenna is fabricated according to the simulation result. The obtained antenna can perform in IEEE802.11a, b(2.4～2.484 GHz and 5.15～5.35 GHz bands) and be adopted for laptop applications. All the measurements are performed in the actual test fixture.

• Information and Communications Magazine
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• v.20 no.6
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• pp.735-745
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• 2003

PDA, 스마트폰, 인터넷단말기, 인터넷TV, 스마트태그 등의 다양한 정보기기는 블루투스, 802.11b, IEEE 1394, CDMA 등의 무선통신 기술 과 융합되어 기존의 고정형 데스크탑 PC 중심의 컴퓨팅 패러다임을 이동형으로 변화시키고 있다. 이러한 패러다임은 사용자가 언제 어디서든지 정보를 접근할 수 있도록 PC(Personal Computer) 기능을 갖는 정보단말을 사용자의 몸에 편하게 지니고 다닐 수 있게 하거나(wearable), 모든 사물에 컴퓨팅 기능을 집어넣어 사용자에게 보이지 않는 컴퓨팅 환경을 제공하는(ubiquitous) 추세로 발전하고 있다. 본 고에서는 이러한 추세에 따른 포스트PC로 일컫는 차세대 정보단말 기술의 발전 방향과 유비쿼터스 네트워크와의 융합에 따라 새롭게 떠오르고 있는 서비스 기술에 대해 살펴보았다.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2138-2139
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• 2006

본 논문에서는 인텔사의 PXA 255 프로세서에 내장형 운영 시스템을 실장하여 미디어 플레이어의 기능을 구현하고, Wireless LAN(IEEE 802.11b)망을 통한 다양한 멀티미디어 컨텐츠를 다운로드할 수 있는 시스템 구현을 보였다. 이를 위하여 리눅스 운영 시스템에 미디어 플레이어와 코덱을 크로스 컴파일하여 보드에 실장하고, 사용자의 편의를 위하여 USB 디바이스 지원과 저장용량 확대를 위한 Compact Flash 메모리 디바이스 지원을 보였다. 또한 사용자 인터페이스를 위하여 Qt/E를 이용하여 어플리케이션을 제작함으로서 사용자의 편의성을 도모하였다.

• TTA Journal
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• s.86
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• pp.83-88
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• 2003

TTA(한국정보통신기술협회, 사무총장 임주환)에서 제공하고 있는 무선랜 장비 TTA Verified 시험은 KT 및 하나로통신의 Benchamarking Test(BMT)의 참가자격 요건으로 Wi-Fi 인증과 함께 공인되고 있는 인증시험으로써, 올해 1월부터 본격적인 시험인증 서비스를 진행해왔다. 본 고에서는 지난 2월과 3월에 걸쳐 진행된 무선랜 TTA Verified 인증시험의 내용 및 결과에 대해서 분석하고 TTA 무선랜 상호운용성 인증마크를 획득한 무선랜 Access Point (AP) 와 Station에 대해서 소개하고자 한다.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.18-23
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• 2008

This paper describes development of real-time condition monitoring system to observe state of a container crane in a port. To analyze the state of a crane, the strength and the direction of wind are measured with sensors along with the load resulted a crane at the moment. The measured signals are processed by especially developed conditioning board and converted into digital data. Measured data are analyzed to define the state of the crane at an indicator. For transmission of these data to the indicator, we implemented wireless sensor network based on IEEE 802.15.4 MAC(Media Access Control) protocol and Bluetooth network protocol. To extend the networking distance between the indicator and sensor nodes, the shortest path routing algorithm was applied for WSN(Wireless Sensor Network) networks. The indicator sends the state information of the crane to monitoring server through IEEE 802.11 b wireless LAN(Local Area Network). Monitoring server decides whether alarm should be issued or not. The performance of developed WSN and Bluetooth network were evaluated and analyzed in terms of communication delay and throughput.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.257-264
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• 2007

In this paper, we have designed and fabricated a wide-band and high gain antenna which can integrate a standard of IEEE 802.1la$(5.15\sim5.25\;GHz,\;5.25\sim5.35\;GHz,\;5.725\sim5.825\;GHz)$. We inserted a parallel dual slot into a rectangular patch to have wide-band, and we offset an element of capacitance from the slot by using coaxial probe feeding method. We also designed a converter of $\lambda_g/4$ impedance with taper type line so that wide-band impedance can be matched easily. We finally designed structure with $2\times2$ array in order to improve the antenna gain, and the final fabricated antenna could have a good return loss(Return loss$\leq$-10 dB) and a high gain(over 13 dBi) at the range of $5.01\sim5.95\;GHz(B/W\doteqdot940\;MHz)$.

• Journal of Digital Convergence
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• v.10 no.3
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• pp.265-271
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• 2012

This paper proposes a communication distance performance evaluation method for mobility of service robots equipped with a Wi-Fi module. Service robots have function of mobile communication system according to classified services and utilize a (preferred) communication method, wireless lan(IEEE802.11 a/b/gin) communication method of ISM band(2.4GHz and 5.8GHz). For evaluating degradation performance of wireless data for the service robot's mobility. We measured and presented reference vectors obtained by utilizing a distance attenuation correlation method in the real world environment. To evaluate performance of the proposed method, path loss of reference vectors was assigned to the Azimuth 301W and then transmission rate and the transmit throughput of the test sample were measured by the Chariot. The proposed measurement method is necessary for securing wireless LAN communication distance for mobility of mobile smart device and service robots. In addition, if the proposed measurement method os adopted, It would be expected that mobile smart device vendors would utilize the method as an effective wireless LAN mobility communication distance performance evaluation method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.5 s.108
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• pp.408-415
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• 2006

This paper suggests an improved system-level model of RF power amplifiers(PAs) including memory effects, and validates the suggested model by analyzing the power spectral density of the output signal with a predistortion linearizer. The original three-box(Wiener-Hammerstein) model uses input and output filters to capture RF frequency response of PAs. The adjacent spectral regrowth that occurs in three-box model can be perfectly removed by Hammerstein structure predistorter. However, the predistorter based on Hammerstein structure achieves limited performance in real PA applications due to other memory effects except RF frequency response. The spectrum of the output signal can be predicted accurately using the suggested model that changes a memoryless block in a three-box model with a memory polynomial. The proposed model accurately predicts the output spectrum density of PA with Hammerstein structure predistorter with less than 2 dB errors over ${\pm}30$ MHz adjacent channel ranges for IEEE 802.11 g WLAN signal.

• Journal of Advanced Navigation Technology
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• v.6 no.3
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• pp.241-250
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• 2002

This paper presents a way to maximize transmission efficiency and reception ability through transmission diversity technology, which can be adapted to wireless multimedia OFDM system. The presented method is a comparative analysis between a case where parameter ${\alpha}$ for time average is 0.3, 1 with consideration of channel presumption with two types of rms delayed spread, which is 50nsec, 150nsec, for the performance analysis of STTC(Space-Time Trellis Code) using time-space ciphering method appropriate for MIMO channel, and performance in the case where presumed channel value from long training column section is applied to according frame in a single frame. The result showed that BER brought SNR improvement of 1.0 dB in $10^{-3}$ when ${\alpha}$ was 0.3 than using only the long training column, and showed increase of general performance improvement for the sake of time average rather than the case without.