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장애물의 기하투영에 의한 일차매개곡선을 이용한 충돌회피 경로계획
남궁인,Nam-Gung, In 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.12
A new algorithm for planning a collision-free path is developed based on linear prametric curve. In this paper robot is assumed to a point, and two linear parametric curve is used to construct a path connecting start and goal point, in which single intermediate connection point between start and goal point is considered. The intermediate connection point is set in polar coordinate(${\theta}{\delta}$) , and the interference between path and obstacle is mapped into CPS(connection point space), which is defined a CWS GM(circular work space geometry mapping). GM of all obstacles in workspace creates overlapping images of obstacle in CPS(Connection Point Space). The GM for all obstacles produces overlapping images of obstacle in CPS. The empty area of CPS that is not occupied by obstacle images represents collision-free paths in Euclidian Space. A GM based on connection point in elliptic coordinate(${\theta}{\delta}$) is also developed in that the total length of path is depend only on the variable .delta.. Hence in EWS GM(elliptic work space geometry mapping), increasing .delta. and finding the value of .delta. for collision-free path, the shortest path can be searched without carring out whole GM. The GM of obstacles expersses all possible collision-free path as empty spaces in CPS. If there is no empty space available in CPS, it indicates that path planning is not possible with given number of connection points, i.e. path planning is failed, and it is necessary to increase the number of connection point. A general case collision-free path planning is possible by appling GM to configuration space obstacles. Simulation of GM of obstacles in Euclidian space is carried out to measure performance of algorithm and the resulting obstacle images are reported.
초기 확산강조 MR 영상에서 음성을 보인 급성기 뇌경색 환자의 임상 양상
남궁인,한갑수,조한진,문성우,최성혁,이병찬 대한응급의학회 2013 대한응급의학회지 Vol.24 No.4
Purpose: Diffusion-weighted magnetic resonance (MR)image (DWI) has advantages for the assessment of acute stroke. However, false negative DWI findings in acute ischemic stroke have been reported. Our purpose was to estimate the rate of initial false negative DWI studies in acute ischemic stroke patients and to identify characteristics of false negative DWI stroke patients. Methods: In this retrospective study from January 2010 to June 2011, acute ischemic stroke patients (within 6 hours after stroke onset) were enrolled. A total of 56 patients were included in this study. Cases with negative initial DWI findings,with an ischemic lesion visible on follow-up MR studies,were analyzed for times between the onset of symptoms and initial DWI, National Institute of Health Stroke Scale (NIHSS), and the location of the ischemic stroke lesion. Results: We found seven cases (12.5%) of false negative initial DWI studies. The initial false negative DWI group had a significantly shorter time from the onset of symptoms to the initial DWI compared to the initial positive DWI group (p=0.011). The false negative group had a lower NIHSS without significance (p=0.091). Conclusion: A false-negative DWI study is not uncommon in the assessment of acute ischemic stroke. Thus, patients suspected of having a stroke should not be ruled out on the basis of a negative DWI, especially a suspected low NIHSS, for an early onset of symptoms.
오흥국,남궁인 亞洲大學校 1983 論文集 Vol.6 No.-
This study is concerned with hot forging of sintered porous metal ring with inner barrier. It is analyzed by Upper Bound approach for finding the normalized forging pressure at various relative densities and shape factors of the test specimens. Experiments are carried out for sintered porous ring, which were compacted with the powders Fe95 + Cu5, Fe90 + Cu10 and Fe47.5 + Cast iron cutting chip powder 47.5 + Cu5. The specimens are heated in the furnace at 1100℃ and then forged in the preheated die at 200℃. The experimental and the analytical results are compared. Possible explanations for the observed effects are discussed.
KSNP+ 원자로덮개 5.5m 수직 낙하 시 원자로내부구조물 건전성 평가
남궁인(Ihn Namgung),정승하(Seung Ha Jeong),이대희(Dae Hee Lee),최택상(Taek Sang Choi) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Due to the application of Integrated Head Assembly (IHA) in KSNP+ reactor design, an investigation of<br/> reactor internals integrity is carried out to assure that the adoption of IHA does not affect the safety of reactor<br/> operation. One of the postulated accident events is the R.V. closure head fall from 5.5m high directly above<br/> the reactor vessel that may occur during the refueling operation. The analysis model consists of lumped mass<br/> elements of the entire reactor vessel and internals. Because of extreme load, separate elastic-plastic analyses<br/> are done for the members that undergo plastic deformation. The analysis verified that the stresses of the<br/> reactor internals and the fuel assemblies are within the bound of allowable stress limits and the integrity of the<br/> fuel assemblies is maintained.