홍성제 교수

We report microporous carbon nanosheets containing numerous redox active heteroatoms fabricated from exfoliated waste coffee grounds by simple heating with KOH for pseudocapacitive charge storage. We found that various heteroatom combinations in carbonaceous materials can be a redox host for lithium ion storage. The bio-inspired nanomaterials had unique characteristics, showing superior electrochemical performances as cathode for asymmetric pseudocapacitors.

In this paper we propose a real-time communication scheme that can be used in general point-to-point real-time multicomputer systems with wormhole switching. Real-time communication should satisfy the two requirements of predictability and priority handling. Since traditional wormhole switching does not support priority handling which is essential in real-time computing, flit-level preemption is adopted in our wormhole switching. Also, we develop an algorithm to determine the message transmissio

Herein, we report the effect of sonoluminescence and an initial dye concentration on the sonophotocatalysis of TiO2 for the degradation of eosin B, a textile dye. We first investigated the light illuminated during ultrasound irradiation (sonoluminescence) by photographic images, a radical indicator (luminol), and photoluminescence spectra of the detection range of 300–1050 nm. Next, we examined the synergistic effect of sonolysis on photocatalysis by comparing the dye degradation of sonophotocat

I/sub DDQ/ testing can cover the traditional stuck-at-faults as well as other defects that may affect reliability. One of the most critical issues in I/sub DDQ/ testing is a built-in current sensor (BICS) that can be used to detect abnormal static currents. The most serious problem in the conventional current sensor is performance degradation. The purpose of this work is to present an effective BICS, which has a very small impact on the performance of the circuit under test (CUT). The proposed B

Since there is no method to verify the trustworthiness of shared files in P2P systems, malicious peers can spread untrustworthy files to the system. In order to prevent these untrustworthy files from spreading, we propose an effective reputation management system using peer reputation and file reputation together in DHT-based structured P2P networks. Simulation results show that the proposed system works better in preventing untrustworthy files from spreading than existing systems even in cases

The problem of finding an optimal product sequence for sequential multiplication of a chain of matrices (the matrix chain ordering problem, MCOP) is well-known. We consider the problem of finding an optimal product schedule for evaluating a chain of matrix products on a parallel computer (the matrix chain scheduling problem, MCSP). The difference between MCSP and MCOP is that MCOP pertains to a product sequence for single processor systems and MCSP pertains to a sequence of concurrent matrix pro

Many optimization schemes have been proposed to reduce the overhead of checkpointing. Incremental checkpointing based on memory page protection has been one of the successful schemes used to reduce the overhead and to improve the performance of checkpointing. In this paper, we propose two checkpointing schemes, called "block encoding" and "combined block encoding", which further reduce the checkpointing overhead. The smallest unit of checkpoint data in our scheme is a block, which is smaller tha

A distance bounding protocol enables one party to determine a practical upper bound on the distance to another party. It is an effective countermeasure against mafia fraud attacks (a.k.a. relay attacks) which do not alter messages between users but only relay messages. The main idea of distance bounding protocols is to repeat fast bit exchanges. One party sends a challenge bit and another party answers with a response bit and vice versa. By measuring the round-trip time between the challenge and

A theorem is presented that simplifies the computations necessary for complementing a Boolean function.

Abstract This study evaluates the two-group interfacial area transport equation (2G IATE) coupled with the S-Gamma ( S γ ) population balance equation (PBE) model for beyond bubbly flow regimes in a vertical large-diameter pipe. The 2G IATE framework incorporates intergroup mass transfer mechanisms and is implemented within the S γ model, which assumes a log-normal bubble size distribution. The numerical approach is validated against experimental data from Schlegel et al. (2012), with a focus on

This correspondence describes two efficient algorithms for determining whether or not a given finite-state machine has a synchronizing sequence and a distinguishing sequence, respectively, and compares them with the well-known tree method. Compared with the tree method, these new algorithms are easier to implement and require less memory size. Since they do not require keeping and searching a look-back directory, they allow significant speed improvements.

The switching function minimization is very important for optimal and reliable PLA design. A number of different minimization procedures have appeared. However, until recently, the application of these minimization procedures has been limited to functions of a few variables. For the automated design of PLA's, we need computationally efficient procedures that can minimize functions of a large number of variables. For this type of function, the commonly used procedures cannot be applied either bec