김종 교수

Power-aware scheduling problem has been a recent issue in cluster systems not only for operational cost due to electricity cost, but also for system reliability. As recent commodity processors support multiple operating points under various supply voltage levels, Dynamic Voltage Scaling (DVS) scheduling algorithms can reduce power consumption by controlling appropriate voltage levels. In this paper, we provide power-aware scheduling algorithms for bag-of-tasks applications with deadline constrai

Twitter can suffer from malicious tweets containing suspicious URLs for spam, phishing, and malware distribution. Previous Twitter spam detection schemes have used account features such as the ratio of tweets containing URLs and the account creation date, or relation features in the Twitter graph. Malicious users, however, can easily fabricate account features. Moreover, extracting relation features from the Twitter graph is time and resource consuming. Previous suspicious URL detection schemes

We present an analytical model for the performance evaluation of hypercube computers. This analysis is aimed at modeling a deadlock-free wormhole routing scheme prevalent on second generation hypercube systems. Probability of blocking and average message delay are the two performance measures discussed. We start with the communication traffic to find the probability of blocking. The traffic analysis can capture any message destination distribution. Next, we find the average message delay that co

Contractors responsible for the whole execution of engineering, procurement, and construction (EPC) projects are exposed to multiple risks due to various unbalanced contracting methods such as lump-sum turn-key and low-bid selection. Although systematic risk management approaches are required to prevent unexpected damage to the EPC contractors in practice, there were no comprehensive digital toolboxes for identifying and managing risk provisions for ITB and contract documents. This study describ

Malicious crowdsourcing, also known as crowdturfing, has become an important security problem. However, detecting accounts performing crowdturfing tasks is challenging because human workers manage the crowdturfing accounts such that their characteristics are similar with the characteristics of normal accounts. In this paper, we propose a novel crowdturfing detection method, called CrowdTarget, that aims to detect target objects of crowdturfing tasks (e.g., post, page, and URL) not accounts perfo

Improvement in the security and availability is important for the success of the Internet of Things (IoT). Given that recent IoT devices are likely to have multiple functionalities and support third-party applications, this goal becomes challenging to achieve. Through an in-depth investigation of existing IoT frameworks, we focused on two inherent security flaws in their design caused by their device-centric approaches: (1) coarse-grained access control and (2) lack of resource isolation. Becaus

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

This paper presents a method of prejoining the expected next TV channels for reducing IPTV channel zapping time with a consideration of the channel surfing behavior and the particular preference of each viewer. In this method, a home gateway of multicast protocol proxy for set-top boxes (STB) prejoins the expected and preferred channels based on aggregated data from STBs. The experimental results show that the method improves the prediction accuracy of prejoin channels with little network bandwi

An efficient processor allocation policy is presented for hypercube computers. The allocation policy is called free list since it maintains a list of free subcubes available in the system. An incoming request of dimension k (2/sup k/ nodes) is allocated by finding a free subcube of dimension k or by decomposing an available subcube of dimension greater than k. This free list policy uses a top-down allocation rule in contrast to the bottom-up approach used by the previous bit-map allocation algor

When a client requests a real-time connection that requires an excessive amount of resources and/or a very high level of QoS, the network service provider may have to reject the request, and only a small number of connections could be accepted. On the other hand, if the client requests only the minimum level of QoS, he may receive only a bare-bones service even when there are plenty of resources available. One way of utilizing resources efficiently is to specify flexible (elastic) QoS requiremen

In this paper, we consider a class of generalized operator equilibrium problems and derive a Minty type lemma for this class of problems. Further, we establish some existence theorems for the generalized operator equilibrium problems. The theorems presented in this paper generalize and unify many well-known results in the literature.

In this paper, we present an analytical model for computing the dependability of hypercube systems. The model, referred to as task-based dependability (TBD), is developed under the assumption that a task needs at least an m-cube (m < n) in an n-cube for its execution. Two probabilistic terms are required for computing this dependability. The first is the probability of any x nodes working out of 2n nodes. The second term is a conditional probability that at least a connected m-cube exists amo

An analytical model for the performance evaluation of asynchronous hypercubes is presented. This analysis is aimed at modeling a deadlock-free wormhole routing scheme prevalent on second-generation hypercube systems. Probability of blocking and average message delay are discussed. The communication traffic to find the probability of blocking is the starting point. The traffic analysis can capture any message destination distribution. The average message delay that consists of two parts is found.