Young Sun Kwon

In this article, we present a novel localization method for multiple sources in indoor environments. Our approach can estimate different propagation paths, including the reflection and diffraction paths of sound waves based on a backward ray tracing technique. To estimate diffraction propagation paths, we combine a ray tracing algorithm with a uniform theory of diffraction model by exploiting the diffraction properties as propagation paths bend around the wedges of obstacles. We reconstruct the

In this paper, we present two novel approaches, super rays and culling region, for efficiently updating grid-based occupancy maps with point clouds. Rays, which traverse from the sensor origin to the sensor data, update the occupancy probabilities of a map representing an environment. Based on the ray model, we define a super ray as a representative ray to multiple rays having the same traversal patterns during the map updates. Our super rays utilize the geometric information of rays and reduce

A Ka‐band push–push voltage‐controlled oscillator (VCO) using a parasitic capacitance cancelling technique is presented. To enhance the oscillation frequency ( f osc ) and the tuning range (TR), the parasitic capacitance of the VCO is cancelled with negative capacitance (NC). To realise NC, a negative impedance circuit (NIC) is analysed and designed. Because of self‐resonance frequency, NC is realised using an open‐circuit stable NIC. For further enhancement of the f osc , the VCO is developed i

The reset current (Ireset), voltage (Vreset), and resistance of the low resistance state, as functions of the compliance current (CC), were investigated in a Pt/NiO/Pt structure that showed unipolar resistance switching. Interestingly, the Ireset and the Vreset measured at low CCs were found to be widely distributed. In order to explain the behavior of the reset parameters for the singly-connected conducting filament (CF) structure, a simple model of CFs was employed whose width variation follow

Mobile robot navigation in crowded indoor environments is a challenging task due to the limited sensing capabilities of onboard sensors. In this study, we propose a mobile robot navigation framework that utilizes external CCTV data to address the limitations of local sensors in a crowded environment. This approach enables mobile robots to navigate safely and efficiently in complex environments by encapsulating human movements from CCTVs to anticipate the human impact on the unclear navigational

In this paper, we present a new approach, AKIMap, that uses an adaptive kernel inference for dense and sharp occupancy grid representations. Our approach is based on the multivariate kernel estimation, and we propose a simple, two-stage based method that selects an adaptive bandwidth matrix for an efficient and accurate occupancy estimation. To utilize correlations of occupancy observations given sparse and non-uniform distributions of point samples, we propose to use the covariance matrix as an

Vision aided dynamic exploration on bipedal robots poses an integrated challenge for perception and control. Rapid walking motions as well as the vibrations caused by the landing-foot contact-force introduce critical uncertainty in the visual-inertial system, which can cause the robot to misplace its feet placing on complex terrains and even fall over. In this paper, we present a streamlined integration of an efficient geometric footstep planner and the corresponding walking controller for a hum

We present a novel approach, Super Ray, for efficiently updating map representations such as grids and octrees with point clouds. In this paper, we define a super ray for points as a representative ray to them with an associated frustum. A super ray is constructed in a way that updating those points has the same set of cells accessed during the map update process. As a result, we can perform the update process with a super ray in a single traversal on the map, resulting in performance improvemen

This paper proposes a real-time system integrating an acoustic material estimation from visual appearance and an on-the-fly mapping in the 3-dimension. The proposed method estimates the acoustic materials of surroundings in indoor scenes and incorporates them to a 3-D occupancy map, as a robot moves around the environment. To estimate the acoustic material from the visual cue, we apply the state-of-the-art semantic segmentation CNN network based on the assumption that the visual appearance and t

Socially acceptable navigation in a crowded environment is a challenging problem in robotics due to diverse and unknown human intent. Previous studies have dealt with the social navigation problem in dense crowds via multi-robot collision avoidance. However, it is intractable to follow social compliant trajectory since human-robot interaction differs from the multi-robot collision avoidance problem. To approach our goal, this work exploits a human behavior model and focuses on social group actio

The set process in a unipolar resistance switching Pt/NiO/Pt thin film was conducted in two different ways: the current-biased set process (current sweep mode) and the voltage-biased set process (voltage sweep mode). In the current-biased set process, a compliance current setting was not necessary for continuing stable resistance switching. The resistance of the low resistance state, the reset and the set switching parameters were compared in both modes of the set processes. The distributions of

This study presents an enhanced exploration path planning for unmanned aerial vehicles. The primary goal is to increase the chances of survival of missing people in forest environments. Exploration path planning is an essential methodology for exploring unknown three-dimensional spaces. However, previous studies have mainly focused on underground environments, not forest environments. The existing path planning methods for underground environments are not directly applicable to forest environmen

We present a novel, robust sound source localization algorithm considering back-propagation signals. Sound propagation paths are estimated by generating direct and reflection acoustic rays based on ray tracing in a backward manner. We then compute the back-propagation signals by designing and using the impulse response of the backward sound propagation based on the acoustic ray paths. For identifying the 3D source position, we use a well-established Monte Carlo localization method. Candidates fo