• Journal of Chest Surgery
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• v.36 no.10
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• pp.748-753
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• 2003

Background: The pulmonary nodules (PN), when indicated, need thoracoscopic resection, especially in cases of non-diagnostic or technically infeasible PCNA (percutaneous needle aspiration). In the difficult situations of small or deeply seated PN, several techniques facilitating thoracoscopy have been used for detecting them. Our new protocol for managing PN was developed and prospectively reviewed. Material and Method: In the procedure of PCNA, we firstly placed the tip of the needle in the center of, or just in contact with PN under CT guidance, and loaded one or two segments of platinum radiomarker inside the needle after removing the stylet. Then, we forced the radiomarker to move to the tip of the needle by pushing the stylet. Finally, if the tip of the needle was not within PN, it was reoriented to the their center to obtain the sample for PCNA. Result: Between May 1999 and May 2000, radiomarkers were successfully placed in 28 PN of 26 patients, with the exception of one. In 18 (85%) of 21 nodules needing throacoscopy, intraoperative fluoroscopy was used to detect them or guide stapling resection during thoracoscopy. Conclusion: The advantages of this technique are that there is that there is no need for further localization for thoracoscopy even in cases of unsuccessful PCNA, and it was more effective in respect to both cost and time. Therefore, this strategy for PN expecting thoracoscopy will be helpful to patients and medical staff alike.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.5
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• pp.412-418
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• 2007

An inverse optimal problem for homing guidance with angular constraint is addressed. The gains of BPN(Biased PN) are investigated by duality analysis related to the weighting matrices of the performance index in the LQ control problem. Moreover, the criteria for the existence of optimal gains are derived from the generalized Riccati equation. Based on the conditions we achieve the gain set of BPN to be optimal solution to the LQ problem with terminal constraints. To validate and demonstrate the proposed approach 3-DOF simulations are carried out.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.4
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• pp.332-340
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• 2011

A missile with a strapdown seeker should properly estimate line-of-sight(LOS) rate using its attitude information and the look angle of the seeker because LOS rate information in an inertial coordinate system, which is used for a proportional navigation(PN) homing guidance, can not be obtained directly. However, an unnecessary feedback loop(Parasite Loop) is formed in the guidance and control loop, and it may cause the guidance performance degradation or even the unstability of the system(Parasite Effect). This paper presents estimation methods for the LOS rate information and effective ways to minimize the parasite effect using Routh-Hurwitz stability criterion. Various numerical simulations are also included to verify the proposed methods.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.8
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• pp.740-744
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• 2008

In this paper, we propose a new time-to-go estimation filter for PN guided missiles. The proposed estimator is derived based on the approximation of the length of the PNG homing trajectory that we newly introduced using the special coordinate system. The coordinate system is convenient for taking the target movement into account. In addition, compared with the previous time-to-go estimation techniques, the parameters required for evaluating the length can be obtained only with the seeker measurements. Moreover, the seeker measurement error statistics can effectively be considered since our filter is derived based on the Kalman filter theory. Simulation result for a typical anti-ship see-skimming missile homing trajectory shows the excellent performance of the proposed filter.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.203-215
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• 2017

Recently, interest in Pedestrian Navigation Service (PNS) is being increased due to the diffusion of smart phone and the improvement of location determination technology and it is efficient to use landmarks in route guidance for pedestrians due to the characteristics of pedestrians' movement and success rate of path finding. Accordingly, researches on extracting landmarks have been progressed. However, preceding researches have a limit that they only considered the difference between buildings and did not consider visual attention of maps in display of PNS. This study improves this problem by defining building attributes as local variable and global variable. Local variables reflect the saliency of buildings by representing the difference between buildings and global variables reflects the visual attention by representing the inherent characteristics of buildings. Also, this study considers the connectivity of network and solves the overlapping problem of landmark candidate groups by network voronoi diagram. To extract landmarks, we defined building attribute data based on preceding researches. Next, we selected a choice point for pedestrians in pedestrian network data, and determined landmark candidate groups at each choice point. Building attribute data were calculated in the extracted landmark candidate groups and finally landmarks were extracted by principal component analysis. We applied the proposed method to a part of Gwanak-gu, Seoul and this study evaluated the extracted landmarks by making a comparison with labels and landmarks used by portal sites such as the NAVER and the DAUM. In conclusion, 132 landmarks (60.3%) among 219 landmarks of the NAVER and the DAUM were extracted by the proposed method and we confirmed that 228 landmarks which there are not labels or landmarks in the NAVER and the DAUM were helpful to determine a change of direction in path finding of local level.