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Park, Cheonman,Lee, Seongbong,Kim, Hyeji,Lee, Dongjin The Institute of Internet 2020 International journal of advanced smart convergenc Vol.9 No.3
In this paper, we study on aerial objects detection and position estimation algorithm for the safety of UAV that flight in BVLOS. We use the vision sensor and LiDAR to detect objects. We use YOLOv2 architecture based on CNN to detect objects on a 2D image. Additionally we use a clustering method to detect objects on point cloud data acquired from LiDAR. When a single sensor used, detection rate can be degraded in a specific situation depending on the characteristics of sensor. If the result of the detection algorithm using a single sensor is absent or false, we need to complement the detection accuracy. In order to complement the accuracy of detection algorithm based on a single sensor, we use the Kalman filter. And we fused the results of a single sensor to improve detection accuracy. We estimate the 3D position of the object using the pixel position of the object and distance measured to LiDAR. We verified the performance of proposed fusion algorithm by performing the simulation using the Gazebo simulator.
제주도 양식 넙치(Paralichthys olivaceus)에서 분리한 병원균 3종에 대한 Mixed Oxidant 및 차아염소산나트륨 살균효과
박천만 ( Cheonman Park ),김기혁 ( Ki-hyuk Kim ),문혜나 ( Hye-na Moon ),여인규 ( In-kyu Yeo ) 한국수산과학회(구 한국수산학회) 2018 한국수산과학회지 Vol.51 No.4
Marine pathogenic bacteria, such as Streptococcus parauberis, Edwardsiella tarda and Vibrio harveyi, can cause lethal infections in farmed fish, ozone and antibiotics, are employed to sterilize waters used for rearing fish to mitigate this threat. The most widely used method is treatment with sodium hypochlorite solution. However, the maintenance of a constant concentration of chlorine in rearing waters can be difficult. We investigated the potential of a mixed oxidant (MO) solution generated by electrolysis of sea water to improve water quality. We measured the survival rates of fish pathogenic bacteria exposed to different concentrations of MO (0.5, 1.0, 1.5 and 2.0 MO) and sodium hypochlorite (0.5, 1.0, 1.5 and 2.0 ppm) for various lengths of time (0, 5, 10, 15, 20, 25 and 30 min). We found a time-dependent decrease in the survival rates of the tested pathogenic microorganisms. The sterilization effect of the MO solution on pathogenic organisms was greater than that of sodium hypochlorite for gram-negative and gram-positive bacteria. We conclude that MO solution produced by electrolysis could be used to maintain a constant chlorine concentration in aquaculture systems.
사육수의 pH변화가 복해마(Hippocampus kuda)에 미치는 생리적 영향
박천만(Cheonman Park),김기혁(Ki-hyuk Kim),문혜나(Hye-Na Moon),여인규(In-Kyu Yeo) 한국생명과학회 2017 생명과학회지 Vol.27 No.7
대기의 이산화탄소의 농도 증가는 해양산성화와 지구온난화를 유발하는 것으로 알려져 있다. 해마는 해양생태계 및 수산자원생물로서 중요한 종으로 알려져 있지만, 최근 해양산성화로 인하여 개체수가 감소되고 있는 실정이다. 따라서 본 연구에서는 멸종 위기 종인 복해마(Hippocampus kuda)에 미치는 생리적 영향을 조사하기 위해서 사육수의 산성조건인 pH 6.0, 6.5, 7.0 및 자연해수(pH 8.0)의 환경에서 복해마(H. kuda)를 15일 동안 사육 후 체내조성 변화 및 항산화 효소 활성 변화에 대하여 조사를 실시하였다. 복해마(H. kuda)의 크기 및 성장은 대조군인 pH 8.0을 제외한 실험군에서는 pH가 저하함에 따라 감소하는 경향을 나타내었다. 체내 조성성분인 회분, 조지방 및 조단백 또한 pH 저하에 따라 농도의존적으로 감소하는 것이 관찰되었다. SOD, CAT 및 GSH와 같은 항산화 효소의 분석 결과, SOD활성의 경우, pH 저하에 따라 농도의존적으로 감소하지만, 이와 상반되게 CAT 및 GSH에서는 pH저하에 따라 활성이 농도의존적으로 증가하는 결과가 나타내었다. 이것은 복해마(H. kuda)가 사육수의 pH 저하에 따른 체내 항상성을 유지하는 과정 중 스트레스가 야기되어 에너지 대사가 손상된 것으로 추정된다. 항산화효소는 일반적으로 산성화 스트레스에 민감하게 작용하는데 본 연구에서도 사육수의 pH 변화에 따라 항산화 효소작용이 유의하게 변화하였다. 이러한 결과로 복해마(H. kuda)에 있어서 산성화 노출을 통한 생리학적 스트레스가 항산화 반응 및 체내 성분과 성장을 저해하는 것으로 여겨진다. The rising concentration of atmospheric carbon dioxide is causing ocean acidification and global warming. The seahorse is an important species in marine ecosystems and fishery markets, however, their populations have recently decreased due to ocean acidification. As a result, we examined changes in the physiological responses of the spotted seahorse Hippocampus kuda when it was exposed to acidic sea water (pH 6.0, 6.5, and 7.0) and normal seawater (pH 8.0 as the control) over a period of 15 days. As the pH decreased, the seahorses’ body weight and length also decreased. Components in body of ash, the crude lipids and crude proteins also differed significantly with changes in pH, due to stress caused by the seahorses’ exposure to the acidic water conditions. The superoxide dismutase levels were significantly lower in the pH 6.0 and 6.5 groups than they were in the pH 7.0 and pH 8.0 groups. However, the catalase and glutathione levels were significantly higher in the acidic sea water groups. We suggest that decreasing the pH level of rearing water induces a stress response in H. kuda, damaging their ability to maintain their homeostasis and energy metabolism. Antioxidant enzymes are generally sensitive to acidic stress; in this study, the antioxidant activity was significantly affected by the pH level of the rearing water. These results indicate that physiological stress, induced by exposure to acidification, induces an antioxidant reaction, which can reduce general components in the body and the growth of H. kuda.
Hyeji Kim,Cheonman Park,Seongbong Lee,Dongjin Lee 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
In this paper, we propose an obstacle states estimation algorithm based on radar and a collision avoidance algorithm based on closest point of approach(CPA) for unmanned aerial vehicles(UAVs), in order to avoid collision with the obstacle that do not provide information. We estimated position of detected objects using radar and compared current position and previous position for matching objects and removing outliers. Among the detected objects, the obstacle was selected the object with the highest risk of collision. The CPA was calculated using estimated states of the UAV and the obstacle. Based on the CPA, we detected collision and generated the velocity command for collision avoidance. The performance of proposed algorithm of states estimation of obstacle, collision detection and avoidance was verified through the flight tests.
UWB based Relative Navigation and Leader-Follower Formation for UAVs using Maneuvering of a Follower
Seongbong Lee,Cheonman Park,Sang-yeoun Lee,Ji Hun Jeon,Dongjin Lee 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10
In this paper, we propose UWB based leader-follower formation flight method. For leader-follower formation flight, relative position between leader and follower is required, but when using only UWB, bearing angle between them is not obtained. In this paper, to estimate relative position we use relative velocity based on reference frame. It assumes that velocities of UAVs are estimated each other using inertial measurement unit and shared through ad-hoc network and change of relative position is estimated by numerically integrating relative velocity. using set of change of relative position and relative distance, we estimate relative position. Conditions that relative position cannot estimate exist, to avoid satisfying it we modified guidance law of one of followers. proposed method is validated through simulation.