Search Results Heading

MBRLSearchResults

mbrl.module.common.modules.added.book.to.shelf
Title added to your shelf!
View what I already have on My Shelf.
Oops! Something went wrong.
Oops! Something went wrong.
While trying to add the title to your shelf something went wrong :( Kindly try again later!
Are you sure you want to remove the book from the shelf?
Oops! Something went wrong.
Oops! Something went wrong.
While trying to remove the title from your shelf something went wrong :( Kindly try again later!
    Done
    Filters
    Reset
  • Discipline
      Discipline
      Clear All
      Discipline
  • Is Peer Reviewed
      Is Peer Reviewed
      Clear All
      Is Peer Reviewed
  • Item Type
      Item Type
      Clear All
      Item Type
  • Subject
      Subject
      Clear All
      Subject
  • Year
      Year
      Clear All
      From:
      -
      To:
  • More Filters
25 result(s) for "Lee, Changyu"
Sort by:
The effect of team emotional intelligence on team process and effectiveness
Team emotional intelligence is expected to have a significant impact on intrateam conflict and team effectiveness. However, to date, there has been a dearth of empirical evidence of this link. Taking a comprehensive approach, our study contributes to the literature on intrateam conflict and team emotional intelligence. Data collected from 79 teams in South Korean companies reveal that team emotional intelligence is negatively related to team process (i.e., task conflict and relationship conflict) and positively related to team effectiveness (i.e., team performance, innovation, and cohesion). In addition, team emotional intelligence has a moderating effect on decoupling task conflict and relationship conflict. Our findings also indicate that team emotional intelligence decreases the negative effects of task conflict on team effectiveness, and of relationship conflict on team cohesion. We conclude this study with a discussion of limitations and implications for future research.
RNA Chaperone Function of a Universal Stress Protein in Arabidopsis Confers Enhanced Cold Stress Tolerance in Plants
The physiological function of Arabidopsis thaliana universal stress protein (AtUSP) in plant has remained unclear. Thus, we report here the functional role of the Arabidopsis universal stress protein, AtUSP (At3g53990). To determine how AtUSP affects physiological responses towards cold stress, AtUSP overexpression (AtUSP OE) and T-DNA insertion knock-out (atusp, SALK_146059) mutant lines were used. The results indicated that AtUSP OE enhanced plant tolerance to cold stress, whereas atusp did not. AtUSP is localized in the nucleus and cytoplasm, and cold stress significantly affects RNA metabolism such as by misfolding and secondary structure changes of RNA. Therefore, we investigated the relationship of AtUSP with RNA metabolism. We found that AtUSP can bind nucleic acids, including single- and double-stranded DNA and luciferase mRNA. AtUSP also displayed strong nucleic acid-melting activity. We expressed AtUSP in RL211 Escherichia coli, which contains a hairpin-loop RNA structure upstream of chloramphenicol acetyltransferase (CAT), and observed that AtUSP exhibited anti-termination activity that enabled CAT gene expression. AtUSP expression in the cold-sensitive Escherichia coli (E. coli) mutant BX04 complemented the cold sensitivity of the mutant cells. As these properties are typical characteristics of RNA chaperones, we conclude that AtUSP functions as a RNA chaperone under cold-shock conditions. Thus, the enhanced tolerance of AtUSP OE lines to cold stress is mediated by the RNA chaperone function of AtUSP.
A learning-based approach to surface vehicle dynamics modeling for robust multistep prediction
Determining the dynamics of surface vehicles and marine robots is important for developing marine autopilot and autonomous navigation systems. However, this often requires extensive experimental data and intense effort because they are highly nonlinear and involve various uncertainties in real operating conditions. Herein, we propose an efficient data-driven approach for analyzing and predicting the motion of a surface vehicle in a real environment based on deep learning techniques. The proposed multistep model is robust to measurement uncertainty and overcomes compounding errors by eliminating the correlation between the prediction results. Additionally, latent state representation and mixup augmentation are introduced to make the model more consistent and accurate. The performance analysis reveals that the proposed method outperforms conventional methods and is robust against environmental disturbances.
Improving the Electroluminescence Properties of New Chrysene Derivatives with High Color Purity for Deep-Blue OLEDs
Two blue-emitting materials, 4-(12-([1,1′:3′,1″-terphenyl]-5′-yl)chrysen-6-yl)-N,N-diphenylaniline (TPA-C-TP) and 6-([1,1′:3′,1″-terphenyl]-5′-yl)-12-(4-(1,2,2-triphenylvinyl)phenyl)chrysene (TPE-C-TP), were prepared with the composition of a chrysene core moiety and terphenyl (TP), triphenyl amine (TPA), and tetraphenylethylene (TPE) moieties as side groups. The maximum photoluminescence (PL) emission wavelengths of TPA-C-TP and TPE-C-TP were 435 and 369 nm in the solution state and 444 and 471 nm in the film state. TPA-C-TP effectively prevented intermolecular packing through the introduction of TPA, a bulky aromatic amine group, and it showed an excellent photoluminescence quantum yield (PLQY) of 86% in the film state. TPE-C-TP exhibited aggregation-induced emission; the PLQY increased dramatically from 0.1% to 78% from the solution state to the film state. The two synthesized materials had excellent thermal stability, with a high decomposition temperature exceeding 460 °C. The two compounds were used as emitting layers in a non-doped device. The TPA-C-TP device achieved excellent electroluminescence (EL) performance, with Commission Internationale de L′Eclairage co-ordinates of (0.15, 0.07) and an external quantum efficiency of 4.13%, corresponding to an EL peak wavelength of 439 nm.
Pohang Canal Dataset: A Multimodal Maritime Dataset for Autonomous Navigation in Restricted Waters
This paper presents a multimodal maritime dataset and the data collection procedure used to gather it, which aims to facilitate autonomous navigation in restricted water environments. The dataset comprises measurements obtained using various perception and navigation sensors, including a stereo camera, an infrared camera, an omnidirectional camera, three LiDARs, a marine radar, a global positioning system, and an attitude heading reference system. The data were collected along a 7.5-km-long route that includes a narrow canal, inner and outer ports, and near-coastal areas in Pohang, South Korea. The collection was conducted under diverse weather and visual conditions. The dataset and its detailed description are available for free download at https://sites.google.com/view/pohang-canal-dataset.
Efficient COLREGs-Compliant Collision Avoidance using Turning Circle-based Control Barrier Function
This paper proposes a computationally efficient collision avoidance algorithm using turning circle-based control barrier functions (CBFs) that comply with international regulations for preventing collisions at sea (COLREGs). Conventional CBFs often lack explicit consideration of turning capabilities and avoidance direction, which are key elements in developing a COLREGs-compliant collision avoidance algorithm. To overcome these limitations, we introduce two CBFs derived from left and right turning circles. These functions establish safety conditions based on the proximity between the traffic ships and the centers of the turning circles, effectively determining both avoidance directions and turning capabilities. The proposed method formulates a quadratic programming problem with the CBFs as constraints, ensuring safe navigation without relying on computationally intensive trajectory optimization. This approach significantly reduces computational effort while maintaining performance comparable to model predictive control-based methods. Simulation results validate the effectiveness of the proposed algorithm in enabling COLREGs-compliant, safe navigation, demonstrating its potential for reliable and efficient operation in complex maritime environments.
Turning Circle-based Control Barrier Function for Efficient Collision Avoidance of Nonholonomic Vehicles
This paper presents a new control barrier function (CBF) designed to improve the efficiency of collision avoidance for nonholonomic vehicles. Traditional CBFs typically rely on the shortest Euclidean distance to obstacles, overlooking the limited heading change ability of nonholonomic vehicles. This often leads to abrupt maneuvers and excessive speed reductions, which is not desirable and reduces the efficiency of collision avoidance. Our approach addresses these limitations by incorporating the distance to the turning circle, considering the vehicle's limited maneuverability imposed by its nonholonomic constraints. The proposed CBF is integrated with model predictive control (MPC) to generate more efficient trajectories compared to existing methods that rely solely on Euclidean distance-based CBFs. The effectiveness of the proposed method is validated through numerical simulations on unicycle vehicles and experiments with underactuated surface vehicles.
Parameter-Varying Koopman Operator for Nonlinear System Modeling and Control
This paper proposes a novel approach for modeling and controlling nonlinear systems with varying parameters. The approach introduces the use of a parameter-varying Koopman operator (PVKO) in a lifted space, which provides an efficient way to understand system behavior and design control algorithms that account for underlying dynamics and changing parameters. The PVKO builds on a conventional Koopman model by incorporating local time-invariant linear systems through interpolation within the lifted space. This paper outlines a procedure for identifying the PVKO and designing a model predictive control using the identified PVKO model. Simulation results demonstrate that the proposed approach improves model accuracy and enables predictions based on future parameter information. The feasibility and stability of the proposed control approach are analyzed, and their effectiveness is demonstrated through simulation.
Nonlinear Model Predictive Control with Obstacle Avoidance Constraints for Autonomous Navigation in a Canal Environment
In this paper, we describe the development process of autonomous navigation capabilities of a small cruise boat operating in a canal environment and present the results of a field experiment conducted in the Pohang Canal, South Korea. Nonlinear model predictive control (NMPC) was used for the online trajectory planning and tracking control of the cruise boat in a narrow passage in the canal. To consider the nonlinear characteristics of boat dynamics, system identification was performed using experimental data from various test maneuvers, such as acceleration-deceleration and zigzag trials. To efficiently represent the obstacle structures in the canal environment, we parameterized the canal walls as line segments with point cloud data, captured by an onboard LiDAR sensor, and considered them as constraints for obstacle avoidance. The proposed method was implemented in a single NMPC layer, and its real-world performance was verified through experimental runs in the Pohang Canal.
EFFECT OF CARBON CONTENTS AND Ti ADDITION ON THE MICROSTRUCTURE OF ULTRA-LOW CARBON STEEL
The microstructures of a series of ultra-low carbon (ULC) steels with various carbon contents (50-200ppm) and Ti addition (>500ppm) were studied by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The specimens were fabricated under the process of hot rolling, cold rolling and a two-step continuous annealing. The experimental results showed that the increase of carbon content decreased grain size, whereas the addition of Ti resulted in a larger grain size compared to those without Ti addition. Dislocation (cell) structures were introduced by cold rolling, but it was removed by the two-step annealing. Only MnS precipitated from the Ti-free specimens. However, a larger amount of fine TiN, a few coarse TiS and the extremely low number of much coarser Ti3AlC were observed in the Ti-added specimens. Besides, the reduction of MnS inclusion was obtained by the addition of the Ti.