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Vision-Based Obstacle Avoidance for UAVs via Imitation Learning with Sequential Neural Networks
Park Bumsoo,오현동 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.3
This paper explores the feasibility of a framework for vision-based obstacle avoidance techniques that can be applied to unmanned aerial vehicles, where such decision-making policies are trained upon supervision of actual human flight data. The neural networks are trained based on aggregated flight data from human experts, learning the implicit policy for visual obstacle avoidance by extracting the necessary features within the image. The images and flight data are collected from a simulated environment provided by Gazebo, and Robot Operating System is used to provide the communication nodes for the framework. The framework is tested and validated in various environments with respect to four types of neural network including fully connected neural networks, two- and three-dimensional convolutional neural networks (CNNs), and recurrent neural networks (RNNs). Among the networks, sequential neural networks (i.e., 3D-CNNs and RNNs) provide the better performance due to its ability to explicitly consider the dynamic nature of the obstacle avoidance problem.
병적 보행 환자의 모션 캡쳐 데이터로부터 근골격 모델 추정
박범수(Bumsoo Park),민세희(Sehee Min),박정남(Jungnam Park),이제희(Jehee Lee) 한국컴퓨터그래픽스학회 2021 한국컴퓨터그래픽스학회 학술대회 Vol.2021 No.7
본 논문에서는 병적 보행 환자의 모션 캡쳐 데이터만으로 가상 환경에서 이와 유사하게 걷는 근골격 모델을 추정할 수 있는 시스템을 구축하는 방법을 제안한다. 모션 캡쳐란 환자의 몸에 마커를 부착한 뒤 시간에 따른 움직임을 기록하는 것이다. 모션 캡쳐 데이터는 모션 캡쳐에서 기록한 마커의 3차원 좌표값들로 구성된다. 이것을 가능하게 만드는 구성 요소는 두 가지가 있다. 첫 번째는 근육 상태와 골격 구조를 매개 변수로 가지는 근골격 모델의 보행 시뮬레이터를 학습하여 사용한 것이다. 이를 이용하면 다양한 근골격 모델의 보행을 추가적인 학습 없이 바로 계산할 수 있다. 두 번째는 근골격 모델의 매개 변수를 입력으로, 시뮬레이션 결과와 보행 데이터의 차이값을 출력으로 하는 함수의 최솟값을 구하는 최적화 문제를 해결하는 방법으로 적합한 근골격 모델을 추정한다. 본 논문은 다양한 환자에 대해 이와 유사한 시뮬레이션 결과를 보이는 근골격 모델을 찾을 수 있음을 보였다.
박범수 ( Bumsoo Park ),안우근 ( Woogeun Ahn ),이장용 ( Jangyong Lee ),고덕곤 ( Duck Kon Ko ) 한국항행학회 2022 韓國航行學會論文誌 Vol.26 No.1
종래 유도탄의 경우 대부분 유도탄의 전방부에 GPS (Global Positioning System) 안테나가 장착되는 경우가 많아 종말 유도단계에서 수직 낙하하는 유도탄의 경우 GPS 안테나가 전방부에 위치하면 동체에 의한 위성 신호 가림 현상이 생겨 GPS 성능이 떨어진다. 본 논문에서는 위성 신호에 대한 가시영역을 최대로 확보하기 위해 GPS 안테나를 유도탄의 후방 부에 기울임을 주어 배치하였으며 배열안테나의 패치를 기울여 설계하는 것을 제안하였다. 제안된 안테나 배치 형상에 대하여 GPS 신호의 신호 수신 범위를 분석하기 위해 LOS (Line Of Sight) 관점에서 가시영역을 분석하였고 실제 무반향 챔버에서 수신 신호 세기 측정을 통해 위성 신호의 유효 수신영역을 분석하였다. 또한 야외시험과 비행시험을 통해서 위성 신호의 음영지역이 줄어드는 것을 확인함으로써 GPS 안테나가 유도탄의 후방에 배치되었을 때 얻을 수 있는 장점을 확인하였다. In this paper we investigate the advantages when the GPS Antenna is installed on the rear missile body. In conventional design the GPS antenna locates on the front part of missile. However it causes degraded GPS positioning performance since the missile body blocks the GPS signals. This paper proposes the GPS array antenna design which locates on the rear part of missile body and has the tilted antenna patches to achieve the maximum area of receiving GPS signals. We simulate LOS region of receiving signals and conducted anechoic chamber test to define the effective signal receiving region. And we conduct field test and flight test to check out the enhancement of signal receiving area.
SWAT 모형을 이용한 보령댐 도수로 운영 방안 및 정책 연구
박범수 ( Bumsoo Park ),윤효직 ( Hyo Jik Yoon ),홍용석 ( Yong Seok Hong ),김성표 ( Sung Pyo Kim ) 한국물환경학회 2020 한국물환경학회지 Vol.36 No.6
While industrialization has provided in abundance, the pollution it creates has caused untold damage to the environment, increasing the frequency and severity of natural disasters through changes in global climate patterns. The World Risk Forum’s (WEF) World Risk Report presented the results of a survey of experts from around the world detailing the most influential risk factors over the next decade. Notably, the failure to respond to climate change ranked first and the global water crisis third. The extreme drought in the western Chungnam province was unexpected in 2016. At the time, the water level of Boryeong Dam was drastically decreased due to receiving less than half the average recorded rainfall in the region that year. The Boryeong Dam diversion pipeline has the capacity to solve the water shortage problem between these two regions by providing water from Geumgang to the western part of Chungnam, including Boryeong City. Current weather trends suggest drought is likely to continue in western Chungnam, which uses the Boryeong Dam as an intake source. This makes it necessary to operate Boryeong Dam diversion pipeline in an efficient and effective manner. SWAT is a watershed scale model developed to predict the impact of land management practices on water. The SWAT model was used in this study to evaluate the adequacy of the Boryeong Dam diversion pipeline operational plan by comparing it to present Boryeong Dam diversion pipeline operation. By investigating the number of days required to reach each reservoir stage, we determined that the number of days required to reach the boundary stage was less than that of the current operation. This determination accounts for the caveats that the Boryeong Dam waterway was not operated and only one pump will be operated from October to May of next year. As our results suggest, the most stable operation scenario is to operate two pumps at all times. This can be accomplished by operating two pumps from the caution stage to increase the number of pumps whenever the stage is raised. In addition to the stable operation of the Boryeong Dam pipeline, policy considerations are required with regard to imposing a water use charge on users of the Boryeong Dam region.
Bumsoo Jeong,Jaemin Jung,Ji Young Park,정성목,Hae-Beom Lee 한국임상수의학회 2016 한국임상수의학회지 Vol.33 No.6
A 2-year-old, castrated male Chihuahua dog was referred for revision surgery for reluxation of the patellafollowing surgery for medial patellar luxation (MPL) of the left stifle joint. On general inspection, the patient showedbilateral hindlimb weight-bearing lameness. On physical examination, bilateral non-reducible MPL was detected throughpalpation. Radiographs revealed bone deformities of both hindlimbs. Computed tomography (CT) was applied for athree-dimensional (3D) printing bone model to establish an accurate surgical plan. The bone plate was pre-contouredover the 3D-printing bone model after execution of corrective osteotomy and sterilized prior to use in surgery. Correctiveosteotomy was performed through a staged, bilateral procedure. The patient showed improvement of limb functionfollowing surgery without reluxation of the patella. The use of 3D-printing bone model for accurate surgical planningof corrective osteotomy appears to be effective in increasing the accuracy of surgery. That may lead to successfulsurgical outcomes.
Kim Bumsoo,Koh Jong Kwan,Park Junyong,Ahn Changui,Ahn Joonmo,Kim Jong Hak,전석우 나노기술연구협의회 2015 Nano Convergence Vol.2 No.19
This paper reports a new type of transmitting mode electrochromic device that uses the high-contrast electrochromism of poly(3,4-ethylenedioxythiophene) (PEDOT) and operates at long-wavelength infrared (8–12 μm) . To maximize the transmittance contrast and transmittance contrast ratio of the device for thermal camouflage, we control the thickness of the thin PEDOT layer from 25 nm to 400 nm and develop a design of grid-type counter electrodes. The cyclability can be greatly improved by selective deposition of the PEDOT film on grid electrodes as an ion storage layer without any loss of overall transmittance. The device with optimized architectures shows a high transmittance contrast ratio of 83 % at a wavelength of 10 μm with a response rate under 1.4 s when alternating voltage is applied. Captured images of an LED lamp behind the device prove the possibility of active, film-type camouflage against thermal detection.