Vol. 4, No. 4, Aug. 2008
Chulho Won, Ben Lee, Kyoung Park, Myung-Joon Kim
Vol. 4, No. 4, pp. 133-144, Aug. 2008
Keywords: Data Transfer, Cache Coherence, User-Level, Low-Latency, Network Protocols, Message, VIA
Show / Hide AbstractClusters have become a popular alternative for building high-performance parallel computing systems. Today¡¯s high-performance system area network (SAN) protocols such as VIA and IBA significantly reduce user-to-user communication latency by implementing protocol stacks outside of operating system kernel. However, emerging parallel applications require a significant improvement in communication latency. Since the time required for transferring data between host memory and network interface (NI) make up a large portion of overall communication latency, the reduction of data transfer time is crucial for achieving low-latency communication. In this paper, Eager Data Transfer (EDT) mechanism is proposed to reduce the time for data transfers between the host and network interface. The EDT employs cache coherence interface hardware to directly transfer data between the host and NI. An EDT-based network interface was modeled and simulated on the Linux-based, complete system simulation environment, Linux/SimOS. Our simulation results show that the EDT approach significantly reduces the data transfer time compared to DMA-based approaches. The EDTbased NI attains 17% to 38% reduction in user-to-user message time compared to the cache-coherent DMA-based NIs for a range of message sizes (64 bytes ~ 4 Kbytes) in a SAN environment.
Hyoungwon Kwak, Poongup Lee, Yohan Kim, Navrati Saxena, Jitae Shin
Vol. 4, No. 4, pp. 145-152, Aug. 2008
Keywords: Home-eNB, 3GPP LTE (Long Term Evolution), Mobility Management
Show / Hide AbstractThe specification of the Home Evolved NodeB (Home-eNB), which is a small base station designed for use in residential or small business environment, is currently ongoing in 3GPP LTE (Long Term Evolution) systems. One of the key requirements for its feasibility in the LTE system is the mobility management in the deployment of the numerous Home-eNBs and other 3GPP network. In this paper, we overview the characteristic of Home-eNB and also describe the mobility management issues and the related approaches in 3GPP LTE based Home-eNB systems.
Sung Joon Ahn
Vol. 4, No. 4, pp. 153-158, Aug. 2008
Keywords: Parametric Curve, Parametric Surface, Space Curve, Curve Fitting, Surface Fitting, Geometric Fitting, Geometric Distance, Least-Squares Approximation, Minimization, Parametric Model Recovery, Object Reconstruction
Show / Hide AbstractThis paper deals with the geometric fitting algorithms for parametric curves and surfaces in 2-D/3-D space, which estimate the curve/surface parameters by minimizing the square sum of the shortest distances between the curve/surface and the given points. We identify three algorithmic approaches for solving the nonlinear problem of geometric fitting. As their general implementation we describe a new algorithm for geometric fitting of parametric curves and surfaces. The curve/surface parameters are estimated in terms of form, position, and rotation parameters. We test and evaluate the performances of the algorithms with fitting examples.
Jeonghye Han, Miheon Jo, Vicki Jones, Jun H Jo
Vol. 4, No. 4, pp. 159-168, Aug. 2008
Keywords: Human-Computer Interaction, Human-Robot Interaction, E-learning, Educational Media, r-Learning, Web-Based Instruction
Show / Hide AbstractHuman-Robot Interaction (HRI), based on already well-researched Human-Computer Interaction (HCI), has been under vigorous scrutiny since recent developments in robot technology. Robots may be more successful in establishing common ground in project-based education or foreign language learning for children than in traditional media. Backed by its strong IT environment and advances in robot technology, Korea has developed the world¡¯s first available e-Learning home robot. This has demonstrated the potential for robots to be used as a new educational media - robot-learning, referred to as ¡®r-Learning¡¯. Robot technology is expected to become more interactive and user-friendly than computers. Also, robots can exhibit various forms of communication such as gestures, motions and facial expressions. This study compared the effects of non-computer based (NCB) media (using a book with audiotape) and Web-Based Instruction (WBI), with the effects of Home Robot-Assisted Learning (HRL) for children. The robot gestured and spoke in English, and children could touch its monitor if it did not recognize their voice command. Compared to other learning programs, the HRL was superior in promoting and improving children¡¯s concentration, interest, and academic achievement. In addition, the children felt that a home robot was friendlier than other types of instructional media. The HRL group had longer concentration spans than the other groups, and the p-value demonstrated a significant difference in concentration among the groups. In regard to the children¡¯s interest in learning, the HRL group showed the highest level of interest, the NCB group and the WBI group came next in order. Also, academic achievement was the highest in the HRL group, followed by the WBI group and the NCB group respectively. However, a significant difference was also found in the children¡¯s academic achievement among the groups. These results suggest that home robots are more effective as regards children¡¯s learning concentration, learning interest and academic achievement than other types of instructional media (such as: books with audiotape and WBI) for English as a foreign language.