• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.215-216
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• 2006

In this paper, the antenna the with linear active phased array of $1{\times}16$ operated in DBS band was designed. The antenna was composed of sixteen radiating elements, sixteen active channels and five Wilkinson power combiners with 4-channel inputs, a digital control board and a stabilizing DC bias board. The radiating element of the array has the structure of a microstrip stack patch with a left-hand circular polarization. And, each active channel consists of a low noise ampilifier, a 3-bit digital phase shifter and a variable analog attenuator. The breadboard of linear active phased array antenna was also fabricated to test the electrical performances. The radiation patterns of the antenna were measured after correcting initial phases of each active channel in aechoic chamber. And also, the beam scanning chracteristcs of $10^{\circ}$, $20^{\circ}$, $30^{\circ}$ were measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.4
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• pp.622-629
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• 2001

An engineering model VCO with a good phase noise for Ku-band satellite transponder is designed using a nonlinear design methodology. It generates frequencies from 1,745 and 1,755 MHz with control voltages from 0 to 5 V DC. This unit requires 7 mA of current from 5 V DC supply voltage. Phase noise characteristics of the manufactured VCO exhibit -114 dBc/Hz @10 kHz offset and -131 dBc/Hz @100 kHz of offset and its output power is 5 dBm.

• Journal of Satellite, Information and Communications
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• v.1 no.1
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• pp.1-4
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• 2006

Ku band satellite signal repeating technology just altering a polarization of the repeated signal is applicable for any kind of satellite broadcasting service in geographically shadowed area due to high-rise buildings, trees, and so on. This paper focuses on the design of high polarization discrimination antenna satisfying polarization characteristics with respect to field pattern and frequency band. Designed antenna for the enhancement of axial ratio and polarization discrimination characteristic shows good performance for satellite broadcasting service repeating system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.55-58
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• 2004

To analysis on the degradation of the satellite communication signal due to Asian dust that was appeared on Korean peninsula during March and April 2004, EIRPs of L, S, C, Ku and Ka frequency band of the downlink of satellite communication link were measured by Satellite Signal Monitoring Center located in lcheon, Korea. The measured results were compared to the measurement values of PM10 and OPC that were measured by the Korea Meteorological Administration.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.6-7
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• 2013

저전송률 오디오 부호화기의 성능 향상을 위해 가변 LPC 기반으로 스펙트럼을 평탄화 하는 방법을 제안한다. 제안한 방법은 대역별 scale factor를 동일하게 하여 비트 효율을 증가시키고 spectral hole이 발생하는 문제점을 해결할 수 있다. 또한, 가변 LPC 필터를 사용하여 프레임 특성에 따라 스펙트럼 평탄화 강도를 가변적으로 조절하여 성능 향상을 제공한다. 제안한 방법이 일반 LPC 필터 방법보다 저대역의 부호화 성능을 향상시키고 스테레오 왜곡을 감소시키는 것을 확인하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.34-40
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• 2001

The necessary of research is proposed about sharing between networks of the fixed-satellite service using non-geostationary satellites and other networks of the fixed-satellite service, interference criteria and calculation methods for the fixed-satellite service because WRC-2000 make a decision that the frequency bands l1/14GHz and 20/30GHz are available to system in the fixed-satellite service employing satellite in both geostationary and non-geostationary orbits. In the paper, four methodologies attempting to derive continuous curves of korea satellite network EPFD(equivalent power flux density) are used.

• Electronics and Telecommunications Trends
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• v.29 no.6
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• pp.1-13
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• 2014

GaN(Gallium Nitride)는 3.4eV의 넓은 에너지 갭으로 인하여 고전압에서 동작이 가능하고, 분극전하를 이용한 캐리어 농도가 높아 높은 전류밀도와 전력밀도를 얻을 수 있으며, 높은 전자 이동도와 포화 속도로부터 고속 동작이 가능하여 고주파 고출력 고효율 소형의 전력증폭기 소자의 재료로 적합하다. 본고에서는 민수 및 군수 겸용 Ku-대역 및 Ka-대역 GaN 고출력 전력증폭기(SSPA: Solid-State Power Amplifier)와 관련된 GaN 전력증폭 소자, GaN 전력증폭기 MMIC(Microwave Monolithic Integrated Circuit), 내부정합 패키지형 GaN 전력증폭기 및 GaN SSPA에 대하여, 국내외 특허 기술동향과 연구개발 기술동향을 중심으로 고찰하고자 한다. 국외의 GaN 고주파 고출력 전력증폭기 기술의 연구동향이나 특허동향을 심층분석하여 연구개발에 활용하고자 한다.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2006.06a
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• pp.101-104
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• 2006

2.4GHz 주파수 대역의 양방향 무선통신을 이용하는 많은 응용분야에 CC2400 칩을 이용한 RF시스템을 연구하였다, 데이터의 송수신을 관리하고 오류제어를 위해 마이크로컨트롤러를 사용하였다. 또한 CC2400은 데이터 처리를 위해 First-In-First-Out이 가능한 버퍼로 마이크로컨트롤러와의 유연한 통신을 제공하며, buster 전송이 가능하고 전송 간격마다 자체적으로 power-down 되어 평균 전력 소비를 줄인다 RF 송수신단에서는 2.4GHz의 주파수로 패킷 단위의 데이터 전송이 가능하도록 시스템 구현이 가능하다. CC2400과 마이크로컨트롤러 사이의 데이터 전송과 제어 신호를 실험을 통해서 확인하였다.

• Journal of Satellite, Information and Communications
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• v.7 no.1
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• pp.102-107
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• 2012

In this paper, we presented interference scenarios and an evaluation methodology for the co-frequency radio interference between a multi-beam mobile satellite communication system and a mobile communication system in 2.1 GHz band. Radio interferences between these systems are calculated using a minimum coupling loss method and an assesment for minimum separation distances was conducted for coexistence of a mobile satellite system and a mobile system in the same geographical area.

• The Journal of the Acoustical Society of Korea
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• v.38 no.1
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• pp.23-29
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• 2019

In this paper, a deep learning-based detection and classification using multi-band frequency signals is presented for detecting earthquakes prevalent in Korea. Based on an analysis of the previous earthquakes in Korea, it is observed that multi-band signals are appropriate for classifying earthquake signals. Therefore, in this paper, we propose a deep CNN (Convolutional Neural Network) using multi-band signals as training data. The proposed algorithm extracts the multi-band signals (Low/Medium/High frequency) by applying band pass filters to mel-spectrum of earthquake signals. Then, we construct three CNN architecture pipelines for extracting features and classifying the earthquake signals by a late fusion of the three CNNs. We validate effectiveness of the proposed method by performing various experiments for classifying the domestic earthquake signals detected in 2018.