• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.843-849
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• 1998

A voltage controlled oscillator using dielectric resonator for 2.4 GHz WLL System is designed and fabricated. To improve the phase noise characteristic resonator is used as an inductor of VCO. At the bias condition of 5 V and 10 mA, the output power and phase noise in the operating frequency range of 2210~2240 MHz are 0 dBm and 100 dBc/Hz 10 kHz offset from the carrier, respectively. The phase noise and harmonic response of fabricated VCO are suitable for WLL system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.462-466
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• 1999

As the spectrum migrates to the higher frequency band around several milimeters wavelength for implementing wideband highspeed communications, it is more important to consider the channel attenuation characteristics of microwave signals. Microwave channels in 27GHz used in B-WLL system must be considered by compensating the power attenuation due to rainfall. So, in the design of one cell, the radiation power enhancement considering rainfall attenuation has an effort on the receiver in other cell as interference. In this paper we consider the main characteristics for B-WLL systems, optimum cell radius, and serviceable limit of heavy rainfall the design of the radiation power control system in case of enhancing the power that prevents from reducing the system capacity by interference.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9B
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• pp.1616-1623
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• 1999

This paper describes error resilient coding scheme is added in WLL system and its application for robust low-bit rate still image transmission over power controlled W-CDA system Rayleigh fading channels. The baseline JPEG compressing methods are uses in image coding over wireless channel. The channel uses Reed-Solomon(RS) outer codes concatenated with convolutional inner codes, and truncated type I hybrid ARQ protocol based on the selective repeat strategy and the RS error detection capability. Simulation results are proved for the statistics of the frame-error bursts of the proposed system in comparison with conventional WLL system. it gains the 2 dB of the Eb/No in same BER.

• Information and Communications Magazine
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• v.15 no.7
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• pp.95-116
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• 1998

• Journal of Yeungnam Medical Science
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• v.38 no.4
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• pp.374-380
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• 2021

Pulmonary alveolar proteinosis (PAP) is an uncommon disease characterized by progressive accumulation of lipoprotein material in the lungs due to impaired surfactant clearance. Whole-lung lavage (WLL) is the current standard treatment and consists of sequential lavage of each lung to mechanically remove the residual material from the alveoli. Although WLL is considered safe, unexpected complications can occur. Moreover, due to the rarity of the disease itself, this procedure is unknown to many physicians, and management of intraoperative complications can be challenging for anesthesiologists. Lung ultrasound (LUS) provides reliable and valuable information for detecting perioperative pulmonary complications and, in particular, quantitation of lung water content. There have been reports on monitoring the different stages of controlled deaeration of the non-ventilated lung during WLL using LUS. However, it has been limited to non-ventilated lungs. Therefore, we report the use of LUS in WLL to proactively detect pulmonary edema in the ventilated lung and implement a safe and effective anesthesia strategy. Given the limited diagnostic tools available to anesthesiologists in the operating room, LUS is a reliable, fast, and noninvasive method for identifying perioperative pulmonary complications in patients with PAP undergoing WLL.

• Journal of the Korean Institute of Navigation
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• v.22 no.1
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• pp.51-54
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• 1998

In this paper, RF receiver for CDMA system which has 10 MHz in the channel bandwidth has been designed and fabricated. The designed and fabricated RF receiver is shown useful in operation and the performance has been confirmed by experiments. The results are to be used for establishment of a broadband CDMA wireless access specification standard for WLL system in 2.3 GHz band.

• Electronics and Telecommunications Trends
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• v.11 no.4 s.42
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• pp.1-11
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• 1996

최근 기존 전화서비스를 무선으로 제공하여, 경제성뿐만 아니라 고속의 데이터 및 팩스서비스에 의한 서비스의 차별화를 이루려는 연구개발이 행해지고 있다. 이같은 가입자선로의 무선화를 위한 시스템을 WLL(Wireless Local Loop)이라 한다. 본 고에서는 먼저 WLL시스템의 구성 및 원리를 살펴보고, 현재 사용중이거나 개발예정인 WLL시스템의 방식 및 특성을 비교분석하였으며, 시스템 계획(planning)에 근거하여 용량, 서비스영역, 음질 등의 관점에서 기존 셀룰러시스템에 대비한 분석결과를 논의하였다. 또한 향후 진화방향 및 표준화동향 등을 검토하였으며 끝으로 결론을 언급하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.315-318
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• 1999

The purpose of this study is to establish the design theory of a DR ceramic bandpass filter used for WLL basestations and to research on the design theory of bandpass filter. The design procedure is circuit parameters and structural parameters will be derived. It was observed that the filter characteristics at the simulations

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.6
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• pp.912-918
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• 2001

This paper presents a performance analysis of experimental observations of a uplink smart antenna system operating in a wide-band CDMA environment designed for a WLL (Wireless Local Loop) system. The numerical results shown in this paper have been obtained from practical experiments using commercially developed mobile terminals. The beam pattern provided by the weight vector and the resultant BER (Bit Error Rate) are observed in both indoor and outdoor signal environments. From the experimental observations, it is concluded that the proposed smart antenna system provides significant improvements in receiving both indoor and outdoor signal environments.

• 한국정보통신설비학회:학술대회논문집
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• 2002.08a
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• pp.193-196
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• 2002

2.3GHz 주파수 대역은 WLL 사업용도로 할당되었으나 현재 환용이 극히 저조한 상태로 남아 있으므로 정부에서는 무선인터넷 서비스용으로의 재활용을 공표하였다. 이와 관련하여 본 고에서는 2.3GHz WLL 주파수를 이용하여 초고속 무선 인터넷 서비스를 제공할 수 있는 고속 무선접속망 기술을 제안한다. 고속 무선접속망은 기지국과 가입자 단말 구간이 무선으로 연결되며, 1Km 거리의 셀 반경 내에서 가입자당 1Mbps의 속도를 보장해주는 형태로 구성된다.