• Journal of KIISE
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• v.44 no.12
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• pp.1245-1251
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• 2017

In this study we present a novel directory architecture that can dynamically allocate a directory entry for a cache block on demand at runtime only when the block is shared by more than one core. Thus, we do not maintain coherence for private blocks, substantially reducing the number of directory entries. Even for shared blocks, we allocate directory entry dynamically only when the block is actively shared, further reducing the number of directory entries at runtime. For this, we propose a new directory architecture called dynamic directory table (DDT), which is implemented as a cache of active directory entries. Through our detailed simulation on PARSEC benchmarks, we show that DDT can outperform the expensive full-map directory by a slight margin with only 17.84% of directory area across a variety of different workloads. This is achieved by its faster access and high hit rates in the small directory. In addition, we demonstrate that even smaller DDTs can give comparable or higher performance compared to recent directory optimization schemes such as SPACE and DGD with considerably less area.

• Journal of Korean Society of Rural Planning
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• v.21 no.2
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• pp.103-114
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• 2015

The comprehensive rural village development projects (CRVDP) have been carried out as the core one of the rural development schemes in Korea since 2004. CRVDP included the various rural experience programs to increase rural income and in order to promote rural community development in the project area. This study analyzed the operating management conditions, types and characteristics of the rural experience programs targeting the 168 CRVDPs have been completed so that the recommendations and lessons which were found the usefulness, challenges and improvements to the CRVDP can be provided to be better the same kinds of rural development projects. We identified the relationships between performances such as increasing village income and utilization of rural amenity resources to the CRVDP and operational management types of the rural experience programs as well. Employing principle component analysis and cluster analysis technique, this study found 5 clusters of rural experience programs among 168 CRVDPs. The results of analysis of variance indicated that there were significant the mean differences between clusters such as the utilization of rural amenity resources(0.01), income of rural experience programs(0.1). According to the result of the Chi-squire test, there was very significant differences between internet homepage operation and clusters(0.01). Finally, the analysis of covariance about the income of rural experience programs showed that there were significant the mean differences between clusters(0.05).

• 한국지구물리탐사학회:학술대회논문집
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• 2009.10a
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• pp.75-80
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• 2009

Despite its flexibility to complex geometry, three-dimensional (3D) electromagnetic(EM) modeling schemes using finite element method (FEM) have been faced to practical limitation due to the resulting large system of equations to be solved. An efficient 3D FEM modeling scheme has been developed, which can adopt either direct or iterative solver depending on the problems. The direct solver PARDISO can reduce the computing time remarkably by incorporating parallel computing on multi-core processor systems, which is appropriate for single frequency multi-source configurations. When limited memory, the iterative solver BiCGSTAB(1) can provide fast and stable convergence. Efficient 3D simulations can be performed by choosing an optimum solver depending on the computing environment and the problems to be solved. This modeling includes various types of controlled-sources and can be exploited as an efficient engine for 3D inversion.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.4
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• pp.86-90
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• 2007

An efficient sensing scheme applicable to DC-DC converters is proposed. The output voltage of the DC-DC converter is fed back and converted to a current signal at the input terminal of the sensor to decide if it is in the tolerable range. The comparison is accomplished by a current push-pull action. With the embedded reference current in the sensor realized from the reference voltage. The advantages of the scheme lie in the fairly accurate and efficient implementation in terms of power consumption and chip size overhead compared with conventional voltage-mode schemes as the major parameter in converting voltage to current is determined by (W/L) aspect ratio of the core transistors. In this paper, a DC-DC converter of 5V output from battery range of 2.2V${\sim}$3.6V adopting the proposed sensing scheme is implemented in a 0.35um CMOS process to prove the validity of the scheme.

• The Journal of the Korea Contents Association
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• v.13 no.2
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• pp.52-61
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• 2013

In wireless sensor networks, the geographical positioning scheme is one of core technologies for sensor applications such as disaster monitoring and environment monitoring. For this reason, studies on range-free positioning schemes have been actively progressing. The density probability scheme based on central limit theorem and normal distribution was proposed to improve the location accuracy in non-uniform sensor network environments. The density probability scheme measures the final positions of unknown nodes by estimating distance through the sensor node communication. However, it has a problem that all of the neighboring nodes have the same 1-hop distance. In this paper, we propose an efficient sensor positioning scheme that overcomes this problem. The proposed scheme performs the second positioning step through the sensing range control after estimating the 1-hop distance of each node in order to minimize the estimation error. Our experimental results show that our proposed scheme improves the accuracy of sensor positioning by about 9% over the density probability scheme and by about 48% over the DV-HOP scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.9
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• pp.4398-4417
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• 2017

Multi-user Multiple-Input and Multiple-Output (MU-MIMO) has potential for prominently enhancing the capacity of wireless network by simultaneously transmitting to multiple users. User selection is an unavoidable problem which bottlenecks the gain of MU-MIMO to a great extent. Major state-of-the-art works are focusing on improving network throughput by using Channel State Information (CSI), however, the overhead of CSI feedback becomes unacceptable when the number of users is large. Some work does well in balancing tradeoff between complexity and achievable throughput but is lack of consideration of fairness. Current works universally ignore the rational utilizing of time resources, which may lead the improvements of network throughput to a standstill. In this paper, we propose TOUSE, a scalable and fair user selection scheme for MU-MIMO. The core design is dynamic-time-warping-based user selection mechanism for downlink MU-MIMO, which could make full use of concurrent transmitting time. TOUSE also presents a novel data-rate estimation method without any CSI feedback, providing supports for user selections. Simulation result shows that TOUSE significantly outperforms traditional contention-based user selection schemes in both throughput and fairness in an indoor condition.

• Smart Media Journal
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• v.4 no.4
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• pp.56-63
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• 2015

Modern GPU can execute mass parallel computation by exploiting many GPU core. GPGPU architecture, which is one of approaches exploiting outstanding computational resources on GPU, executes general-purpose applications as well as graphics applications, effectively. In this paper, we investigate the impact of memory-efficiency and performance according to number of CTAs(Cooperative Thread Array) on a SM(Streaming Multiprocessors), since the analysis of relation between number of CTA on a SM and them provides inspiration for researchers who study the GPU to improve the performance. Our simulation results show that almost benchmarks increasing the number of CTAs on a SM improve the performance. On the other hand, some benchmarks cannot provide performance improvement. This is because the number of CTAs generated from same kernel is a little or the number of CTAs executed simultaneously is not enough. To precisely classify the analysis of performance according to number of CTA on a SM, we also analyze the relations between performance and memory stall, dram stall due to the interconnect congestion, pipeline stall at the memory stage. We expect that our analysis results help the study to improve the parallelism and memory-efficiency on GPGPU architecture.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5B
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• pp.435-447
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• 2003

Current existing network dimensioning method simply relies on long-time measurement data or uses average traffic characteristics of users. In this paper, we propose an efficient network dimensioning method for DiffServ over MPLS networks. First, User's SLA information is distributed from edge nodes to core nodes according to the proposed algorithm. Then at each link, class-based capacity planning is performed. For capacity planning, we proposed sets of network design parameters for DiffServ classes and bandwidth allocation schemes that are most suitable for each class. We have developed a DiffServ over MPLS network design tool using the proposed method. Simulation results show that our proposed method is able to design efficiently the required class link resources.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.57-66
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• 2010

In this paper, we propose the reliability constrained resource allocation scheduling algorithm in cellular network for uplink transmission, where uplink transmission is supported via packet switching schemes without the dedicated uplink circuit links. We evaluate the performance of the proposed algorithm, and compared with the conventional works to identify the pros and cons. The proposed uplink scheduling algorithm is to satisfy the constraints requirements of the MTC services which is considered as the core technology for future mobile wireless networks. It is different to conventional works which target to maximize the link capacity. The proposed algorithm provides reliable uplink transmission independent to the location and the quality of the wireless link of the mobile terminal. Based on the performance evaluation results, we conclude that the proposed method provides enhanced reliability performance than conventional works.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.760-770
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• 2011

The existing mobility management schemes do not fully support the next generation network, which is composed of IP-based core network and various access networks. Currently, ETRI has been developing the AIMS (Access Independent Mobility Service) system which satisfies the ITU-T requirements of mobility management in the next generation network. The AIMS system is designed to provide a mobile host with a fast and reliable mobility service among heterogeneous access networks. Recently, many user devices have multiple communication interfaces, e.g., 3G and WLAN, and thus they can make two or more network connections at the same time. In this paper, we design a scheme of flow mobility, i.e., the movement of selected data flows from one access technology to another, to be applied in the AIMS system, and verify the proposed scheme through the NS-3 simulation study. From the simulation results, we can know that the proposed flow mobility scheme can utilize the network resource efficiently in the heterogeneous mobile networks.