ISAR 영상 형성을 위한 PPP 기반 회전운동 보상기법 연구

강기봉(Ki-Bong Kang),박상홍(Sang-Hong Park),강병수(Byung-Soo Kang),유보현(Bo-Hyun Ryu),김경태(Kyung-Tae Kim) 한국전자파학회 2018 한국전자파학회논문지 Vol.29 No.2

비선형적으로 회전하는 표적의 inverse synthetic aperture radar(ISAR) 영상을 형성하기 위해서는 표적의 수신 신호에 적절한 회전운동 보상기법을 수행해 주어야 한다. 대표적인 회전운동 보상기법인 prominent point processing(PPP)은 산란점의 위상정보를 이용하여 비선형 회전성분을 선형화하는 기법이다. 본 논문에서는 integrated cubic phase function(ICPF)을 이용하여 산란점의 위상정보를 추정한 다음 PPP를 수행하여 ISAR 영상을 형성하는 방법을 제안한다. ICPF는 다수의 산란점으로부터 중첩된 신호가 수신되었을 때 1차원 영역(domain)의 최댓값을 찾는 작업을 수행함으로써 산란점의 위상정보를 추정할 수 있다. 시뮬레이션 결과 ICPF를 이용한 산란점 위상정보 추정 후 PPP를 수행함으로써 지배적 산란점이 존재하지 않는 환경에서 실시간으로 높은 품질의 ISAR 영상을 획득하였다. In order to form focused inverse synthetic aperture radar(ISAR) images of a non-uniformly rotating target, rotational motion compensation(RMC) should be performed. Prominent point processing(PPP), one of the most representative RMC methods, is used to compensate nonlinear rotation motion by exploiting the phase signals of scatterers. In this paper, we propose a new RMC method based on the integrated cubic phase function(ICPF). The ICPF requires only one-dimensional(1-D) maximization to estimate the phases of multi-component signals. Simulation results using a point scatterers model in the absence of dominant scatterers validate that PPP based on ICPF can achieve well-focused ISAR images in real time.

산악지형 풍력발전단지에 의한 추적레이더 정확도 영향 분석

강기봉(Ki-Bong Kang),정주호(Joo-Ho Jung),김민(Min Kim),박상홍(Sang-Hong Park) 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.3

Currently many wind turbines that are the core business of new renewable energy are being built in mountainous areas under the supervision of Korean government. However, many military tracking radars are being operated near a wind turbine area. As a result, a threat to the national security can be incurred when performing military operations. Thus it is required to analyze the radar signal considering the operation of wind turbines on the mountain. In this paper, we propose a method to analyze the effect on the tracking radar by the wind turbine The proposed method is based on the modeling of the radar signal and the mountain, the blockage analysis. Simulation result shows that the proposed method successfully analyzes time-varying accuracy of the tracking radar.

효율적인 헬리콥터 블레이드 분리 및 주요 파라미터 추정 기법

강기봉(Ki-Bong Kang),정주호(Joo-Ho Jung),김민(Min Kim),김경태(Kyung-Tae Kim),박상홍(Sang-Hong Park) 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.8

Various helicopters that is used by belligerent nations are major threats to the ground operation. Therefore, it is very important to avoid the damage in advance and recognize the exact model of the helicopter by using the radar. Major parameters related to helicopter blades are important factors to recognize helicopters. However, existing hough transform methods to estimate major parameters such as the number of blades, length of blades, rotation velocity may causes the problem choosing local minimum. This paper proposes an efficient method to estimate the parameter, which can be applied to the received signal by several blades. The proposed method separates the blade signal by applying complex independent component method and estimates the parameters by using particle swarm optimization, and successfully estimated the parameters of the model.

산악지형에 설치된 풍력발전단지에 의한 도플러 주파수 추출 및 분석

정주호(Joo-Ho Jung),강기봉(Ki-Bong Kang),김민(Min Kim),김정연(Jeung-Yuen Kim),박상홍(Sang-Hong Park) 한국마린엔지니어링학회 2015 한국마린엔지니어링학회지 Vol.39 No.9

물질순환모델을 이용한 제주항의 수질관리(II) -제주항의 수질 특성과 오염부하량 산정-

조은일(Eun Il Cho),강기봉(Ki Bong Kang) 한국환경과학회 2003 한국환경과학회지 Vol.12 No.3

The purpose of this study is to investigate the characteristics of water quality in Jeju harbor and to estimate pollutant loadings discharged into Jeju Harbor. To know characteristics of water quality in Jeju harbor and pollutant loadings of Sanzi river, we have investigated from August, 2000 to May, 2001. The results showed that the concentrations of COD, DIN and DIP were in the range of 1.00~4.85㎎/L(mean 2.15㎎/L), 2.14~74.0㎍-at/L(mean 12.20㎍-at/L) and 0.52~4.00㎍-at/L(mean 1.18㎍-at/L), respectively. There values were under Ⅲ class of seawater quality criteria. The ratio of nitrogen to phosphorus was lower than 16 except for Station 1 in Jeju harbor. Therefore, nitrogen was playing an important role in phytoplankton growth as limiting factor in Jeju harbor. The mean values of eutrophication index were exceeding 1, which was the eutrophication criteria. The results of estimating pollutant loadings at Sanzi river are 0.30 ton/day for COD, 300㎏/day for DIN and 18.0㎏/day for DIP, respectively.

편대비행 표적식별을 위한 효과적인 ISAR 영상 합성 방법

김민(Min Kim),강기봉(Ki-Bong Kang),정주호(Joo-Ho Jung),김경태(Kyung-Tae Kim),박상홍(Sang-Hong Park) 한국전자파학회 2016 한국전자파학회논문지 Vol.27 No.8

본 논문에서는 편대비행 중인 다수의 표적을 식별하기 위하여 기존의 표적들을 분리시키는 기법을 이용하는 대신 PSO(Particle Swarm Optimization) 알고리즘을 이용하여 미리 학습되어 있던 각 표적의 역합성 개구면 레이다(Inverse Synthetic Aperture Radar: ISAR) 영상들을 합성하는 방법을 제안한다. 제안된 기법에서 ISAR 영상의 합성은 표적의 수와 관측 각도 및 표적의 위치를 변수로 하는 비선형문제를 최적화함으로써 수행된다. 추적 레이다를 통하여 관측 각도가 추정됨을 가정한 후, 표적의 수와 위치는 PSO로 템플릿 매칭(template matching)을 최적화 하여 추정된다. 축소된 크기의 F-16을 사용한 시뮬레이션 결과, 편대비행 중인 표적들의 ISAR 영상과 동일한 ISAR 영상이 합성됨으로써 제안된 기법의 효용성이 검증되었다. This paper proposes a novel method for the recognition of the inverse synthetic aperture radar(ISAR) image of multiple targets flying in formation. Rather than separating the ISAR image of each target, the proposed method combines an ISAR image obtained by fusing the ISAR images in the training database. Fusion is conducted by optimizing the non-linear problem whose parameters are the aspect angle and the target location. Assuming that the aspect angle is properly estimated, the proposed method estimates the number of the targets and their locations by optimizing the template matching using PSO. In simulations using the F-16 scale model, the efficiency of the proposed method was demonstrated by yielding the ISAR image identical to that of targets in formation.

풍력발전단지에 의한 레이다 차폐 현상 및 도플러 측정 데이터 분석

김민(Min Kim),강기봉(Ki-Bong Kang),박상홍(Sang-Hong Park),정주호(Joo-Ho Jung) 한국전자파학회 2016 한국전자파학회논문지 Vol.27 No.8

현재 화석연료의 고갈 및 신재생 에너지의 필요성에 따라서 바람이 풍부한 해안지대에서 풍력발전단지가 건설되고 있다. 하지만 군사작전 지역 인근에 풍력발전단지가 건설되어질 경우, 풍력발전기의 레이다 차폐 현상 및 도플러 변조로 인하여 운용 중인 군사 레이다에 방해 현상을 초래할 수 있다. 이에 따라 실제 풍력발전기를 통한 전자기적 현상의 분석이 필요하다. 본 논문에서는 기존 문헌의 발전기 형태에 따른 이론적인 차폐거리 및 레이다 신호 모델링을 통하여 얻어진 도플러 주파수와 실제 운용되는 풍력발전기에서 측정된 전자기적 차폐거리 및 도플러 주파수의 비교를 수행하였다. To cope with the rising cost of the fossil fuel and the need of renewable energy, many wind farms are being constructed along the coasts of Korean peninsula. However, construction of these wind farms may cause negative influences by the shielding effect and the Doppler frequency from the wind turbine on the military radars operated in the nearby region. Therefore, the analysis of electromagnetic phenomenon with the real wind turbine is required. This paper compare the measured electromagnetic shielding effect and Doppler effect with theoretical shielding effect according to obstacle in literature and the extracted Doppler frequency through signal modeling.

기동특성을 사용한 우주표적들 간의 변별 성능 분석

최인오(In-O Choi),강기봉(Ki-Bong Kang),김시호(Si-Ho Kim),정주호(Joo-Ho Jung),김경태(Kyung-Tae Kim),박상홍(Sang-Hong Park) 한국정보기술학회 2017 한국정보기술학회논문지 Vol.15 No.11

Detection and tracking of ballistic missile can be possible when the discrimination between space-targets is possible. Since representative space-targets such as warhead and decoy have similar shapes, radar crosssection (RCS) and high resolution range profile are not suitable for discrimination. In this paper, an effective discrimination method based on the ballistic factor is proposed. The proposed method uses Kalman-filter to track a real-time maneuvering trajectory and extracts the ballistic factor from an estimated trajectory at altitudes less than 100km. Since the ballistic factor of warhead is generally larger than decoys, effective discrimination is conducted. In simulations using the RCS values predicted by the physical optics in which targets are engaged in high-maneuver and micro-motion, the proposed method efficiently discriminated targets.

고강도-고인성 라인파이프강 개발 동향

유장용(Jang-Yong Yoo),강기봉(Ki-Bong Kang) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4

Linepipe steels with a low carbon acicular ferrite microstructure have been recently developed to accommodate the current transportation condition of the gas and oil industry, and they are finally applied to West- East pipeline project in China. By adopting acicular microstructure, both better formability and better toughness could be obtained due to low yield ratio and fine grained microstructure. Mechanical properties of pipe are not greatly different from those of base plates or hot coils with a microstructure of acicular ferrite. Merits of introducing higher strength steels are well known, i.e., reducing the gauge of pipe and the material cost, increasing the welding speed and decreasing construction cost because of reducing the construction period. Threfore, gas and oil industry has required higher strength steel than API-X70 grade steel. Under this background, API-X80 steel has been developed and shall be applied to the several projects. In this paper, developing stage of API-X80 steel is also presented and discussed.

자가-회전 운동을 겪는 표적의 고품질 ISAR 영상 형성을 위한 RMC와 결합된 RCMC 프로세싱 체인

유보현(Bo-Hyun Ryu),강병수(Byung-Soo Kang),강기봉(Ki-Bong Kang),이명준(Myung-Jun Lee),김경태(Kyung-Tae Kim) 한국전자파학회 2021 한국전자파학회논문지 Vol.32 No.1

자가-회전 운동을 겪는 표적의 경우, 표적의 비 균일한 회전 운동에 의하여 형성된 역합성 개구면 레이다(inverse synthetic aperture radar: ISAR) 영상에 1) 산란점들이 거리 방향으로 움직이는 거리 셀 천이(range cell migration: RCM) 현상과 2) 형성된 ISAR 영상에 도플러(Doppler) 방향으로의 퍼짐 현상이 야기된다. 상기 현상들은 각각 거리 셀 천이 보상(RCM correction: RCMC)과 회전 운동 성분 보상(rotational motion compensation: RMC)을 수행하여 보상할 수 있으나, 현재까지의 ISAR 신호처리 기법에서는 RCMC와 RMC가 독립적으로 수행되고 있는 상황이다. 이에 본 논문에서는 RCMC와 RMC를 결합하여, 자가-회전 운동을 겪는 표적의 비 균일 회전 성분에 의한 모든 ISAR 영상의 품질 저하 현상을 보상하는 처리 체계(processing chain)를 제안한다. 본 논문에서는 모의시험 및 실측 해상 표적 데이터를 활용하여 제안된 처리 체계의 효용성을 검증하였다. In ISAR imaging, a self-rotating target induces a nonuniform rotational motion (RM) between the radar and the target. Because the non-uniform RM results in the range cell migration (RCM) in the range-compressed data and blurring effects in the obtained ISAR images, it is highly desirable to properly compensate for the non-uniform RM of the target for the purpose of focusing ISAR images. Fortunately, in conventional ISAR imaging methods, the aforementioned effects due to the non-uniform RM can be eliminated by performing RCMC and RMC, respectively. Nonetheless, in the existing methods, RCMC and RMC have been conducted separately, yielding unfocused ISAR images of self-rotating targets. Therefore, in this paper, we propose an ISAR imaging processing chain that combines RCMC and RMC. Furthermore, experimental results based on simulated and real measured data are provided to demonstrate the effectiveness of the proposed scheme.