김세환 교수

This paper explores sizing and topology reconfiguration strategies for charging and discharging multiple supercapacitors as energy storage in sub-Watt-scale energy harvesters. To maximize energy efficiency for storage ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\eta_{E_{\rm storage}}$</tex></formula> ), total leakage power is kept low by selecting the supercapacitors to charge sequentially, alterna

MoS2 thin-film transistors (TFTs) are fabricated and simulated to explore the NO2 gas sensing mechanism depending on different device structures. In particular, the role of the Al2O3 passivation layer on the MoS2 channel has been investigated. In the case of nonpassivated MoS2 TFTs, increase of off-current is observed with NO2 gas, which has been modeled with the modulation of the effective Schottky barrier height for holes because of the generation of in-gap states near the valence band as NO2

This paper presents an online 3D modeling and tracking methodology that uses aerial photographs for mobile augmented reality. Instead of relying on models which are created in advance, the system generates a 3D model for a real building on the fly by combining frontal and aerial views with the help of an optical sensor, an inertial sensor, a GPS unit and a few mouse clicks. A user’s initial pose is estimated using an aerial photograph, which is retrieved from a database according to the user’s G

This paper discusses issues of using wireless sensor systems to monitor structures and pipelines in the case of disastrous events. The platforms are deployed and monitored remotely on lifetime systems, such as underground water pipelines. Although similar systems have been proposed for monitoring seismic events and the structure health of bridges and buildings, several fundamental differences necessitate adaptation or redesign of the module. Specifically, rupture detection in water delivery netw

Recently, in various fields, research into the path tracking of autonomous vehicles and automated guided vehicles has been conducted to improve worker safety, convenience, and work efficiency. For path tracking of various systems applied to autonomous driving technology, it is necessary to recognize the surrounding environment, determine technology accordingly, and develop control methods. Various sensors and artificial-intelligence-based perception methods have limitations in that they must lea

In this paper, we propose a new method for generating an image-based 3D panoramic virtual environment (VE). The panoramic VE is generated using 3D depth information estimated from rotating two multiview cameras. Even though conventional 2D image-based mosaicking methods provide a wide view, they have limitations in providing a user with a navigation-enabled virtual environment. In order to resolve such obstacles, we first estimate the depth of the scene using two calibrated multiview cameras and

Here we describe a simple sol-gel method to fabricate inverted organic photovoltaics (OPV) using interconnected TiO2 nanotubes (inter-TiO2 NT) as an efficient electron transport layer. Three-dimensionally inter-TiO2 NT arrays were prepared by spin-coating a TiO2 precursor solution on the ZnO nanorod (NR) template grown via the liquid phase deposition method. Upon etching of ZnO NRs, inter-TiO2 NT arrays were generated, as confirmed by X-ray diffraction (XRD), energy-filtering transmission electr

A fundamental issue in content-based image retrieval is how to select image features that can represent image contents appropriately. A multi-scale color clustering algorithm based on human perceptual properties of color images is proposed for image retrieval. The multi-scale clustering algorithm is an unsupervised clustering method that utilizes the perceptual uniformity property in the (p,q) color space. The proposed color clustering algorithm produces a small set of representative color vecto

A registration method is proposed for 3D reconstruction of an indoor environment using a multi-view camera. In general, previous methods have a high computational complexity and are not robust for 3D point cloud with low precision. Thus, a projection-based registration is presented. First, depth are refined based on temporal property by excluding 3D points with a large variation, and spatial property by filling holes referring neighboring 3D points. Second, 3D point clouds acquired at two views

The acquisition of surround-view panoramas using a single hand-held or head-worn camera relies on robust real-time camera orientation tracking and relocalization. This paper presents robust methodology and evaluation for camera orientation relocalization, using virtual keyframes for online environment map construction. In the case of tracking loss, incoming camera frames are matched against known-orientation keyframes to re-estimate camera orientation. Instead of solely using real keyframes from

The increasing complexity of mathematical models developed as part of the recent advancements in autonomous mobility platforms has led to an escalation in uncertainty. Despite the intricate nature of such models, the detection, decision, and control methods for autonomous mobility path tracking remain critical. This study aims to achieve path tracking based on pixel-based control errors without parameters in the mathematical model. The proposed approach entails deriving control errors from a mul