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- 저자 : 이한림(Lee Han Lim) (검색결과 15 건)
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재구성 스위칭 매트릭스와 에러 보정회로를 포함한 4×4 다중 포트 증폭 시스템
이한림(Han Lim Lee),박동훈(Dong-Hoon Park),이원석(Won-Seok Lee),강승태(Seung-Tae Khang),이문규(Moon-Que Lee),유종원(Jong-Won Yu) 한국전자파학회 2014 한국전자파학회논문지 Vol.25 No.6
본 논문에서는 재구성 가능한 스위칭 매트릭스와 위상 및 진폭 에러 보정회로를 포함하는 새로운 구조의 4×4 다중 포트 증폭(MPA) 시스템을 제안한다. 제안하는 재구성 스위칭 매트릭스는 MPA 시스템의 입출력 하이브리드 매트릭스 회로로 사용되며, 스위칭 매트릭스의 스위치 모드 조절을 통해 신호의 증폭에 사용될 증폭기의 개수 및 신호의 출력 방향, 출력 크기를 유동적으로 조절할 수 있다. 또한, 제안하는 MPA 시스템은 증폭기간의 위상 및 이득 오차를 최소화하기 위한 보정 회로를 포함하여, 각각의 신호 경로에 이상적인 위상 및 진폭 밸런스를 만들 수 있기에 MPA 최종 출력단의 포트간 격리도를 향상시키게 된다. This paper presents a new 4×4 multi-port amplifier(MPA) structure using reconfigurable switching matrices as input and output hybrid matrices(IHM, OHM), and phase/amplitude error calibration circuits. According to the mode selection of the switches, output power can be flexibly and effectively managed since the number of PA’s to be used and the number of output port to distribute/combine amplified signals can be controlled. In addition, the proposed structure contains the phase and amplitude error calibration block that helps produce identical amplitudes and desired phase differences to the 4×4 OHM, resulting in optimizing the port-to-port isolation of the MPA system.
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지상원격측정 MAX-DOAS 시스템과 위성 OMI센서로 서울에서 산출된 이산화질소 층적분농도의 비교연구
이한림 ( Han Lim Lee ) 대한원격탐사학회 2013 대한원격탐사학회지 Vol.29 No.2
NO2 vertical column densities were retrieved via ground based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements for the first time for 6 months over the spring season in 2007 and 2008 in Seoul, one the megacities in the Northeast Asia. The retrieved NO2 vertical column densities were compared with those obtained from space borneOzone Monitoring Instrument (OMI). Over the entire measurement period, the NO2 vertical column densities measured by MAX-DOAS ranged from 1.0×10 15 molec·cm -2 to 6.0×10 16 molec·cm -2 while those obtained by OMI ranged 1.0×10 15 molec·cm -2 to 7.0×10 16 molec·cm -2. The correlation coefficient between NO2 vertical column densities obtained from MAX-DOAS and OMI is 0.73 for the entire measurement period whereas the correlation coefficient of 0.85 is found for the dates under the clear sky condition. The cloudy condition is thought to play a major role in increase in uncertainty of the retrieved OMI NO2 vertical column densities since air mass factor may induce high uncertainty due to the lack of cloud and aerosol vertical distribution information.
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라이다를 이용한 지역 대기중 꽃가루의 광학적 두께 산출
노영민 ( Young Min Noh ),이한림 ( Han Lim Lee ),( Detlef Mueller ),이권호 ( Kwon Ho Lee ),최영진 ( Young Jean Choi ),김규랑 ( Kyu Rang Kim ),최태진 ( Tae Jin Choi ) 대한원격탐사학회 2012 대한원격탐사학회지 Vol.28 No.1
Air-borne pollen, biogenically created aerosol particle, influences Earth`s radiative balance, visibility impairment, and human health. The importance of pollens has resulted in numerous experimental studies aimed at characterizing their dispersion and transport, as well as health effects. There is, however, limited scientific information concerning the optical properties of airborne pollen particles contributing to total ambient aerosols. In this study, for the first time, optical characteristics of pollen such as aerosol backscattering coefficient, aerosol extinction coefficient, and depolarization ratio at 532 nm and their effect to the atmospheric aerosol were studied by lidar remotes sensing technique. Dual-Lidar observations were carried out at the Gwangju Institute of Science & Technology (GIST) located in Gwagnju, Korea (35.15°E, 126.53°N) for a spring pollen event from 5 to 7 May 2009. The pollen concentration was measured at the rooftop of Gwangju Bohoon hospital where the building is located 1.0 km apart from lidar site by using Burkard trap sampler. During intensive observation period, high pollen concentration was detected as 1360, 2696, and 1952 m_3 in 5, 6, and 7 May, and increased lidar return signal below 1.5km altitude. Pollen optical depth retrieved from depolarization ratio was 0.036, 0.021, and 0.019 in 5, 6, and 7 May, respectively. Pollen particles mainly detected in daytime resulting increased aerosol optical depth and decrease of Angstrom exponent.
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Flat Panel Phased Array Antenna for 2-D Wide-Angle Beam Steering
Ye-Bon Kim(김예본),Woo-Hee Lim(임우희),Seung-Won Oh(오승원),Junhyuk Cho(조준혁),Han Lim Lee(이한림) 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.6
This paper proposes a new refractive dielectric lay-up antenna technology which generates 2-dimensionally (E- and H-planes) wide beamwidth. The proposed antenna is a compact planar structure and thus can be effectively used for mmWave/sub-THz flat panel phased array with 2-D wide scan angles. To verify the proposed antenna, both single and 4x4 array structures in E- and H- planes were fabricated and compared with the conventional patch antenna at 28 GHz. The array antennas are integrated with a 4-channel beamforming IC to perform beam scanning. The proposed 4x4 array antenna measured scan angle in E-plane and Hplane were 156° and 156° whereas the conventional patch antenna showed the measured scan angle in E- and H- planes of 90° and 86° at 28 GHz. Lastly, high speed modulation test is also performed by comparing general patch and proposed 4x4 array antennas. Error Vector Magnitude (EVM) characteristics of the 64-QAM signal are verified according to the transmission position with beamforming performance.
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위성자료와 다중회귀분석법을 이용한 아시아 주요도시의 포름알데하이드 칼럼농도 추정연구
최원이 ( Won Ei Choi ),홍현기 ( Hyun Kee Hong ),박준성 ( Jun Sung Park ),이한림 ( Han Lim Lee ) 대한원격탐사학회 2015 대한원격탐사학회지 Vol.31 No.6
A Multiple Regression Method (MRM) is used for the first time with Ozone Monitoring Instrument (OMI) and Moderate Resolution Imaging Spectroradiometer (MODIS) data to estimate formaldehyde (HCHO) Vertical Column Density (VCD). For a 3.5-year period from January 2005 through July 2008, HCHO VCD estimation is investigated in cities over Asia in two categorized areas: (1) Major cities in Northeast Asia (Beijing, Seoul, and Tokyo), (2) Major cities in Southeast Asia (New Delhi, Dhaka, and Bangkok). In the Major cities in Northeast Asia, there are good agreements between HCHO estimated by the multiple linear regression method (HCHOMRM) and HCHO measured by OMI (HCHOOMI) (0.78 < R2 < 0.82). However, in Major cities in Southeast Asia, there were poor agreements between HCHOOMI and HCHOMRM (0.24 < R2 < 0.39). In addition, an unbiased assessment of the MRM performance using modeling and validation groups shows that the performance of the MRM based on separate modeling and validation groups is comparable to that using all the data for deriving Multiple Regression Equations(MREs). This study demonstrates that MRM can be an alternative tool for HCHO estimation in certain areas over Asia.
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