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Computational Methods for a Linear Array of Oscillators
Sunggoo Cho,Bum Soo Lee 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.47 No.4
A linear array of oscillators with unequal masses and spring constants has some potential for many applications in various fields of pure and applied sciences. Recently, the solutions of such a linear array of oscillators have been suggested as having the forms of ‘modified’ Bessel functions and following some computational rules that allow their coefficients to be found. In this work, we reformulate those rules as a matrix multiplication, which makes it easier to find, in a systematic manner, the solutions for a system with generic boundary conditions. We also obtain a method for estimating error bounds as a by-product. We demonstrate the usefulness of our method by applying it to some examples.
Collision-free local planner for unknown subterranean navigation
Jung, Sunggoo,Lee, Hanseob,Shim, David Hyunchul,Agha-mohammadi, Ali-akbar Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.4
When operating in confined spaces or near obstacles, collision-free path planning is an essential requirement for autonomous exploration in unknown environments. This study presents an autonomous exploration technique using a carefully designed collision-free local planner. Using LiDAR range measurements, a local end-point selection method is designed, and the path is generated from the current position to the selected end-point. The generated path showed the consistent collision-free path in real-time by adopting the Euclidean signed distance field-based grid-search method. The results consistently demonstrated the safety and reliability of the proposed path-planning method. Real-world experiments are conducted in three different mines, demonstrating successful autonomous exploration flights in environment with various structural conditions. The results showed the high capability of the proposed flight autonomy framework for lightweight aerial robot systems. In addition, our drone performed an autonomous mission in the tunnel circuit competition (Phase 1) of the DARPA Subterranean Challenge.
김성구(Sunggoo Kim),이성길(Sungkil Lee) Korean Institute of Information Scientists and Eng 2016 정보과학회논문지 Vol.43 No.4
Deferred Shading is a shading technique that postprocesses pixels in the screen space, following geometry-only rendering passes with depth buffering. Unlike typical shadow mapping techniques, this technique allows us to render shadows from multiple light sources without changing the structure of the rendering pipelines. This paper presents a deferred shadow mapping technique and its extension to soft shadows using mipmapping. Our technique first generates visibility maps from light sources, and blurs the visibility maps for deferred shading. This strategy leads to efficient soft-edged shadows, but does not incorporate depth variation, producing light bleeding to some extent. In order to suppress the light-bleeding artifacts, we also propose a depth-adaptive mipmap sampling technique in the screen space.