유민수 교수

We describe our experiments on a real-time system design, focusing on design alternatives such as scheduling jitter, sensor-to-output latency, intertask communication schemes and the system utilization. The prime objective of these experiments was to evaluate a real-time design produced using the period calibration method (Gerber et al., 1995) and thus identify the limitations of the method. We chose a computerized numerical control (CNC) machine as our target real-time system and built a realis

This paper presents a control theoretic approach to optimizing end-to-end timing constraints subject to the performance requirements and the schedulability constraint of a real-time control system. The control performance is specified in terms of control output responses such as steady state error maximum overshoot, settling time, and rise time; and the end-to-end timing constraints include loop processing periods and input-to-output latency. Our approach includes a generic real-time controller

This paper presents an automatic approach to synthesizing schedulable timing constraints for real-time control systems. Given the performance specifications and schedulability constraints of a real-time control system, the approach derives task-level timing constraints which can guarantee these req uirements. The control performance is specified in terms of control output responses such as steady state error, maximum over-shoot, settling time, and rise time, and the task-level timing constraints

AbstractWith the increased uses of the Internet, the number of newly found malware keeps increasing every year. In addition, malware becomes more and more complex with various technologies, such as packing, anti-debugging, and so on. To defend against a large number of malware every day, the improvement of the analysis process is quite important. One way of expediting malware analysis processing is to classify unknown or new malware into known malware families. A malware family is a group of mal

In this paper, we present a novel Byzantine fault-tolerant consensus protocol for sharded blockchain networks that does not rely on expensive leader-driven communication. The proposed protocol selects a single block proposer at a time and uses threshold signatures as a voting mechanism to confirm the validity of the proposed block. By using a gossip-like communication scheme, each node can collect and recover the group signature within <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathM

An in-vehicle infotainment (IVI) system is connected to heterogeneous networks such as Controller Area Network bus, Bluetooth, Wi-Fi, cellular, and other vehicle-to-everything communications. An IVI system has control of a connected vehicle and deals with privacy-sensitive information like current geolocation and destination, phonebook, SMS, and driver's voice. Several offensive studies have been conducted on IVI systems of commercialized vehicles to show the feasibility of car hacking. However,

This paper proposes a new voice web browser that can be operated in smart TV environments. Previous voice web browsers had the limitation of being run under limited conditions; for example, a list of the specific contents of a page was outputted by voice, or the user entered a search term by voice. In our method proposed in this paper, all the hierarchical menu areas on a web page are recognized and controlled with voice keywords so that page navigation according to a menu can be conveniently do

In order to improve the performance of a real‐time system, asymmetric multiprocessors have been proposed. The benefits of improved system performance and reduced power consumption from such architectures cannot be fully exploited unless suitable task scheduling and task allocation approaches are implemented at the operating system level. Unfortunately, most of the previous research on scheduling algorithms for performance asymmetric multiprocessors is focused on task priority assignment. They si

Discretely synchronized, distributed real-time systems may suffer from a time discontinuity problem in that local clocks observe the disappearance or reappearance of time intervals. This problem occurs since traditional discrete clock synchronization algorithms adjust local clocks instantaneously. Such time discontinuities may lead to runtime faults due to the loss or gain of critical time points such as task release times and deadlines. In this paper, we propose a dynamic constraint transformat

We propose a dynamic constraint transformation technique for ensuring timing requirements in a distributed real time system, possessing periodically synchronized distributed local clocks. Traditional discrete clock synchronization algorithms that adjust local clocks instantaneously yield time discontinuities. Such time discontinuities lead to the loss or the gain of critical time points such as task release times and deadlines, thus raising run-time faults. While continuous clock synchronization

This paper formulates a problem of embedded real-time system re-engineering, and presents its solution approach. The re-engineering of an embedded system is defined as a development task of meeting newly imposed performance requirements after its hardware and software have been fully implemented. The performance requirements may include a real-time throughput and an input-to-output latency. The proposed solution approach is based on a bottleneck analysis and nonlinear optimization. Inputs to the