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Selective Goal Aiming Rapidly Exploring Random Tree Path Planning for UAVs
노기문,박지훈,한동인,이대우 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.6
As the utilization of UAVs increases, real-time path planning is becoming more important so that paths around unpredictable obstacles can be created and modified along with the overall mission plan. The sampling-based rapidly exploring random tree (RRT) algorithm has advantages of fast computation and low computational complexity. While these characteristics are suitable for real-time path planning, there is a limitation that they cannot guarantee an optimal path. In this paper for the on-board path planning algorithm, the selective goal aiming RRT algorithm is proposed to improve the optimality of path while taking advantage of the RRT algorithm. In this algorithm, a randomly sampled node is selectively moved to a target direction by a certain ratio to generate a tree oriented toward a target point. As a result, an improved path can be generated in less time than the several kinds of RRT algorithm, and the performance of the algorithm is verified by comparison with the original RRT algorithm, biased RRT
DTED 맵에서 무인기 경로 생성을 위한 Probabilistic RoadMap 병렬화
노기문(Geemoon Noh),박지훈(Jihoon Park),민찬오(Chanoh Min),이대우(Daewoo Lee) 한국항공우주학회 2022 韓國航空宇宙學會誌 Vol.50 No.3
본 논문에서는 무인기의 경로 계획을 위한 산악 지형, 레이더 그리고 방공망 등을 3차원 환경으로 구현하고, Sampling 기반의 경로 계획 알고리즘인 PRM 알고리즘을 사용하여 경로 계획 및 재계획을 수행하는 방안에 대해 서술한다. 기존의 PRM 알고리즘의 경우 생성된 노드 사이에 장애물 존재 여부를 확인하기 위한 계산이 노드 간 1:1로 이루어지고 연속적으로 수행되어 노드 수나 노드를 연결하는 거리에 계산량이 크게 영향을 받는다. 이러한 부분을 개선하기 위해 제안하는 LineGridMask 기법을 통해 장애물 존재 여부 확인 방식을 단순화하고, 병렬화를 통해 경로 계획의 계산 시간을 감소시킨다. 마지막으로 기존 PRM 알고리즘과의 성능을 비교한 결과, 경로 계획에서는 최대 88%, 재계획의 경우 최대 94%까지 계산 시간이 감소하였음을 확인하였다. In this paper, we describe how to implement the mountainous terrain, radar, and air defense network for UAV path planning in a 3-D environment, and perform path planning and re-planning using the PRM algorithm, a sampling-based path planning algorithm. In the case of the original PRM algorithm, the calculation to check whether there is an obstacle between the nodes is performed 1:1 between nodes and is performed continuously, so the amount of calculation is greatly affected by the number of nodes or the linked distance between nodes. To improve this part, the proposed LineGridMask method simplifies the method of checking whether obstacles exist, and reduces the calculation time of the path planning through parallelization. Finally, comparing performance with existing PRM algorithms confirmed that computational time was reduced by up to 88% in path planning and up to 94% in re-planning.
Cortisone이 X-線照射「마우스」의 自家感梁에 미치는 影響
盧起文,金箕洪 우석대학교 의과대학 1968 우석의대잡지 Vol.5 No.2
This study was undertaken to evaluate the cortisone effect on autoinfection caused by intestinal bacteria after whole body irradiation. Three hundred and seventy four mice were divided into group 1, 2, 3 and 4, consisting of 60, 84, 100 and 130 mice respectively. Three hundred R of whole body X-irradiation was given in group 1 and 2, and 400R in group 3 and 4. In the mice of group 2 and 4, 0.25㎎ of cortisone were given daily until 20th day following irradiation. Six mice from each group were sacrificed on the 3rd, 6th, 8th, 10th, 12th, 14th, 17th, 21st, and 24th day, and quantitative cultures of blood, liver and spleen were carried out. Blood was not cultured from the mice which died spontaneously during the experiment. The results were as follow. 1. Mortality rate was 6.7, 23.7, 21 and 36.1% in group 1, 2, 3 and 4 respectively. This means that the mortality rate was increased to 3.5 and 1.7 times in cortisone administered groups(group 2 and 4), as compared with that of simply irradiated groups(group 1 and 3). Three hundred R irradiation with cortisone administration showed about equal mortality rate as 400 R irradiation alone. 2. Mice died spontaneously were seen during the 9th to 15th day in group 1, 4th to 19th day in group 2, 3rd to 21st day in group 3, and 1st to 23rd in group 4. This results signify that animal death in the cortisone administered groups occured over the longer period. 3. The mortality rate in the 1st, 2nd and 3rd week in each group was 0, 5, 2%; 7, 12, 5%; 5, 11, 5%; 8, 17, 10%; namely mortality in the 2nd week was highest in all groups. 4. In sacrificed mice of group 1, 2, 3 and 4 bacteria were isolated in 7, 19, 15 and 28% respectively. The rate of positive cultures was higher in the cortisone administered groups, and the 2nd week showed highest positivity in all groups. 5. The rate of positive cultures from blood, liver and spleen in sacrificed mice of each group showed 25, 100, 50%; 50, 100, 90%; 25, 100, 100%; 53, 93, 86%. The results mean the highest positive culture in the liver while the lowest in the blood. Higher rate of positive culture was noted in the blood when cortisone was administered, and negative culture was mainly seen in the early period in all groups. 6. Throughout the entire course of the study, there was nearly 100% of positive culture in the mice died spontaneously. Total 92 mice, including 4, 20, 21, 47 in group 1. 2. 3 and 4 respectively, were died and all were positive except for one in group 1. 7. Eight species of bacteria were isolated; they were Proteus(46%), E. coli(23%), paracolon(19%), alpha-hemolytic streptococcus(6%), Aerobacter(2%), Pseudomonas(2%), unidentified grammegative rod(2%), Staphyloco,cus aureus(1%). Proteus was most commonly isolated. 8. The distribution of bacteria species isolated showed no significant differences between mice died spontaneously and those sacrificed with simple irradiation or cortisone administration. 9. There was negative blood culture in group 1 during the entire course of the study, but bacteremia occured during the 10th to 17th day in group 2, 3 and 4. When cortisone was administered, both the rate of positive culture and colony counts were increased. 10. Until the 8th day number of colonies, in general, were higher in the spleen than in the liver, but after 10th day higher in the liver than in the spleen.