홍승우 교수

A climbing robot that can rapidly move on diverse surfaces such as floors, walls, and ceilings will have an enlarged operational workspace compared with other terrestrial robots. However, the climbing skill of robots in such environments has been limited to low speeds or simple locomotion tasks. Here, we present an untethered quadrupedal climbing robot called MARVEL (magnetically adhesive robot for versatile and expeditious locomotion), capable of agile and versatile climbing locomotion in ferro

Many studies have attempted to predict chlorophyll-a concentrations using multiple regression models and validating them with a hold-out technique. In this study commonly used machine learning models, such as Support Vector Regression, Bagging, Random Forest, Extreme Gradient Boosting (XGBoost), Recurrent Neural Network (RNN), and Long–Short-Term Memory (LSTM), are used to build a new model to predict chlorophyll-a concentrations in the Nakdong River, Korea. We employed 1–step ahead recursive pr

This paper presents a constrained nonlinear model predictive control (NMPC) framework for legged locomotion. The framework assumes a legged robot as a floating base single rigid body with contact forces being applied to the body as external forces. With consideration of orientation dynamics evolving on the rotation manifold SO(3), analytic Jacobians which are necessary for constructing the gradient and the Gauss-Newton Hessian approximation of the objective function are derived. This procedure a

This study aims to compare the classification performance of statistical models on highly imbalanced kidney data. The health examination cohort database provided by the National Health Insurance Service in Korea is utilized to build models with various machine learning methods. The glomerular filtration rate (GFR) is used to diagnose chronic kidney disease (CKD). It is calculated using the Modification of Diet in Renal Disease method and classified into five stages (1, 2, 3A and 3B, 4, and 5). D

As the mobile handheld devices equipped with fingerprint sensors are produced, it becomes important to protect the private information of a user (i.e., fingerprint image) in the remote applications. In this paper, we consider the possible scenarios to transmit fingerprint images from the handheld device to a server securely using both encryption and watermarking. Moreover, to transmit the large-sized fingerprint images via a restricted bandwidth, the image compression should be considered. Based

Due to the severe resource constraints of sensor hardware, energy efficiency is one of critical factors for monitoring the movement of the large-scale phenomena such as wild fire and hazardous bio-chemical material, denoted by continuous objects. In order to save energy, most of existing research on tracking the continuous objects focuses on finding the ways to minimize the communication cost through the effective data delivery such as data aggregation and reducing the number of reporting nodes,

Since the fuel injection pressure in diesel engines is one of the main parameters which determine the emissions and the fuel efficiency, a precise control algorithm for the common-rail pressure is a required priority for improving the engine performances. This paper proposes a coordinated common-rail pressure control strategy for passenger car diesel engines using a metering unit and a pressure control valve. The metering unit, which is located at the high-pressure pump, adjusts the inlet fuel f

This study proposed a gain scheduled controller for exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems with a model-based gain scheduling strategy to manage strong nonlinearity in diesel engines. The feedback controller uses a gain scheduling strategy to obtain appropriate controller gains of the PI controller under various engine operating conditions. The gain scheduling strategy is designed using the proposed static gain model that predicts varying static gains of

This paper proposes a model-based gain scheduling strategy of a Skogestad internal model control (SIMC)-based boost pressure controller for passenger car diesel engines. This gain scheduling strategy is proposed with a new scheduling variable to handle the nonlinear variable geometric turbocharger (VGT) plant characteristics. The scheduling variable is derived from the pressure ratio between the exhaust and intake manifolds and the exhaust air-to-fuel ratio to estimate the static gain of the VGT

This paper proposes a common rail pressure controller based on an empirical rail pressure model for passenger car diesel engines. The controller consists of pressure control valve (PCV) control algorithm and metering unit (MeUn) control algorithm. The PCV control algorithm controls the leakage fuel flow of the common rail based on the empirical rail pressure model. The proposed rail pressure model describes the relation between the common rail pressure and the driving current of the PCV as a qua

The purpose of this study is to determine preferred locations for various in-vehicle controls that require manipulation during vehicle operation and to analyze differences of customer’s preference between Korean drivers and American drivers. 23 in-vehicle controls that are related to the interior design of vehicles were considered in terms of the frequency of use and the need for quick operation. They are switches for outside rearview mirrors, cruise controls, etc. Frequency of use means how oft

This paper proposes a decoupler design method to reduce interaction between exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems in passenger car diesel engines. The EGR valve and VGT vane are respectively used to control air-to-fuel ratio (AFR) of exhaust gas and intake pressure. A plant model for EGR and VGT systems is defined by a first order transfer function plus time-delay model, and the loop interaction between these systems is analyzed using a relative normali

This paper presents a simplified decoupler-based multivariable controller with a gain scheduling strategy in order to deal with strong nonlinearities and cross-coupled characteristics for exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems in diesel engines. A feedback controller is designed with the gain scheduling strategy, which updates control gains according to engine operating conditions. The gain scheduling strategy is implemented by using a proposed schedulin

In order to monitor continuously moving phenomena such as wile fire and hazardous bio-chemical material in wireless sensor network, boundary tracking approach has been widely used by reason of its huge scale and extensive diffusion property. With the boundary tracking scheme, the energy efficiency is expected to improve if only sensor nodes near the boundary of continuous object actively participate in tracking process, while other sensor nodes stay in sleep mode for energy saving. In this paper

This paper proposes three different methods to estimate the low-pressure cooled exhaust gas recirculation (LP-EGR) mass flow rate based on in-cylinder pressure measurements. The proposed LP-EGR models are designed with various combustion parameters (CP), which are derived from (1) heat release analysis, (2) central moment calculation, and (3) principal component analysis (PCA). The heat release provides valuable insights into the combustion process, such as flame speed and energy release. The ce