• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.12
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• pp.1219-1228
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• 1991

In the actual case, a model of noise canceller using adaptive filter has both a channel transfer function from noise source to main signal input and to noise canceller input. The previous models of noise canceller have been considered to be only one side channel transfer function. Therefore, it is proposed that a new model has two channel transfer functions and derives an optimal tranfer function of adaptive noise canceller. The adaptive filter is using the joint process lattice filter that has fast adaptive speed. The signal noise radio has been improved by a model of ANC-ALE and it is confirmed with computer simulation. Beside, a dc bias is very effective for noise cancelling, especially to the particular signal.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.7
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• pp.730-738
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• 1992

This paper alms to analyse the performance of frequency hopping /spread spectrum multiple access system by employing the channel with mixture of AWGN, partial band Jamming, fading and user interference. The performance analysis of FH /SSMA system, taking account of frequency 'hit'(user Interference ) which occurs in the presence of multiple user, produces the following numerical results by computing error probability and throughput of each code in two cases whether the side Information about channel is used or not. The numerical results are as follows : When composite interferences coexist In channel, RS code Is significantly superior to convolutional code in terms of performance. Concatenated code provides the same performance as RS code. The above results show that RS code is pertinent as error-correction code.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.37-46
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• 2018

A design study on the cooling channel configuration in a regeneratively cooled supersonic combustor was performed. The flow parameters on the hot- and cold-side channels were calculated using a quasi-one-dimensional model. The heat transfer between these two sides was estimated as a part of the flow calculation. For the reference configuration, the total amount of heat exchanged was 10.7 kW, the heat flux was $566kW/m^2$, and the fuel temperature increase between the inlet and outlet was 153 K. Seven designs of the heat exchanger channel were compared for their heat transfer performance.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.2
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• pp.135-143
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• 2022

In this paper, the compact waveguide slot array antenna for interferometric radar altimeter is proposed. The proposed antenna structure consist of corrugation structure which is applied between each channel to improve isolation, three-channel waveguide slot array antenna and feeder. In addition, to reduce the occurrence of phase ambiguity, the baseline spacing of the three-channel antenna is analyzed and the results are applied to the design. For compact design, reduced height and SMP connector structure are used and the dip brazing method which is the conjugation method after dipping to flux is used for the fabrication of the lightweight antenna. The measurement result of the proposed antenna shows less than 1.41 : 1 (VSWR) and 48.3 dBc (isolation). The antenna gain is higher than 20.2 dBi and the side lobe levels are lower than 18.8 dB (vertical plane) and 10.0 dB (horizontal plane).

• ETRI Journal
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• v.46 no.2
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• pp.323-332
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• 2024

Receiver and transmitter monolithic microwave integrated circuit (MMIC) multifunction chips (MFCs) for active phased-array antennas for Ka-band satellite communication (SATCOM) terminals have been designed and fabricated using a 0.15-㎛ GaAs pseudomorphic high-electron mobility transistor (pHEMT) process. The MFCs consist of four-channel radio frequency (RF) paths and a 4:1 combiner. Each channel provides several functions such as signal amplification, 6-bit phase shifting, and 5-bit attenuation with a 44-bit serial-to-parallel converter (SPC). RF pads are implemented on the bottom side of the chip to remove the parasitic inductance induced by wire bonding. The area of the fabricated chips is 5.2 mm × 4.2 mm. The receiver chip exhibits a gain of 18 dB and a noise figure of 2.0 dB over a frequency range from 17 GHz to 21 GHz with a low direct current (DC) power of 0.36 W. The transmitter chip provides a gain of 20 dB and a 1-dB gain compression point (P1dB) of 18.4 dBm over a frequency range from 28 GHz to 31 GHz with a low DC power of 0.85 W. The P1dB can be increased to 20.6 dBm at a higher bias of +4.5 V.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.60-63
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• 2003

Resistance performance of 3 G/T class coastal leisure boat is experimentally investigated at high speed ranges and the effect of a fin attached at hull side is studied together. Wave patterns are observed to make clear the relation between the resistance performances and the wave characteristics.

• The KSFM Journal of Fluid Machinery
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• v.3 no.2 s.7
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• pp.36-43
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• 2000

This study presents the centrifugal compressor performance for three different vane stagger angles and wall pressure distribution within vaned diffuser channels, and is also discussed about the stability with respect to the compressor components. As the vane stagger angle decreases, the flow rate for the stall onset decreases, and higher pressure can be obtained at the low flow rate region, however, the effective operation range of the compressor decreases because of the blockage effect of the diffuser vane. Low pressure pocket within the vaned diffuser channel moves from the pressure side of leading edge to the suction side as the flow rate decreases. The compressor system stability mainly depends on that of the diffuser.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.265-268
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• 1998

본 논문에서는 1채널(mono)이나 2채널(stereo)의 오디오 입력을 5채널(center, left, right, left side, right side)로 출력시키는 음장 시스템을 설계하고 그 성능을 분석하였다. 가정의 리스닝 룸 같이 작은 공간에서 콘서트 홀 같은 커다란 공간의 음장을 재현하기 위한 멀티 채널 음장 시스템은 지연기, 초기 반사음처리기, 잔향기를 이용해 설계하였다. 초기 반사음 처리기의 지연과 이득은 실제 공간에서 측정한 암펄스 응답을 이용하여 결정하였으며, 구현된 초기 반사음을 전방 30$^{\circ}$방향에서 재생함으로써 확장감을 증가시킬 수 있도록 하였다. 잔향기는 자연스러운 주파수 및 감쇠 특성을 갖도록 설계되었으며, 후방 60$^{\circ}$방향에서 재생되는 잔향의 상관 계수를 작게 함으로써 청취시 공간감을 느끼게 하였다. 설계된 음장 시스템은 무향실 데이터를 입력으로 시뮬레이션되었고, 그 결과로 얻어진 5개의 PCM 출력은 멀티 트랙 재생 장치에 의해 일반 리스닝 룸에서 재생된다.

• Journal of Yeungnam Medical Science
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• v.5 no.2
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• pp.235-238
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• 1988

Duplication of the urethra within a single penile shaft is a rare anomaly. These can be divided into those that are in the sagittal plane, which is most common, and those that occur side by side. In some cases, the accessory channel is complete, having a separate bladder opening and no communication with the more normal ventral urethra. In other cases, the accessory urethra is incomplete, either ending blindly or communicating with the urethra distal to the bladder neck. We report on a 20-year-old male with incomplete double urethra.

• Proceedings of the KSRS Conference
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• v.1
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• pp.71-74
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• 2006

Communication Ocean Meteorological Satellite (COMS) is planned to be launched onto Geostationary Earth Orbit in 2008. The meteorological imager (MI) is one of COMS payloads and has 5 spectral channels to monitor meteorological phenomenon around the Korean peninsular intensively and of Asian-side full Earth disk periodically. The MI has on-board radiometric calibration capabilities called 'blackbody calibration' for infrared channels and 'space look' for infrared/visible channels, and radiometric response stability monitoring device called 'albedo monitor' for visible channel. Additionally the MI has on-board function called 'electrical calibration' for the check of imaging path electronics of both infrared and visible channels. The characterization of MI performance is performed to provide the pre-launch radiometric calibration data which will be used for in-orbit radiometric calibration with the on-board calibration outputs. The radiometric calibration of the COMS MI is introduced in the view point of instrument side in terms of in-orbit calibration devices and capabilities as well as the pre-launch calibration activities and expected outputs.