• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.1-7
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• 2018

The IoT environment provides an infinite variety of services using many different devices and networks. The development of the IoT environment is directly proportional to the level of security that can be provided. In some ways, lightweight cryptography is suitable for IoT environments, because it provides security, higher throughput, low power consumption and compactness. However, it has the limitation that it must form a new cryptosystem and be used within a limited resource range. Therefore, it is not the best solution for the IoT environment that requires diversification. Therefore, in order to overcome these disadvantages, this paper proposes a method suitable for the IoT environment, while using the existing block cipher algorithm, viz. the lightweight cipher algorithm, and keeping the existing system (viz. the sensing part and the server) almost unchanged. The proposed BCL architecture can perform encryption for various sensor devices in existing wire/wireless USNs (using) lightweight encryption. The proposed BCL architecture includes a pre/post-processing part in the existing block cipher algorithm, which allows various scattered devices to operate in a daisy chain network environment. This characteristic is optimal for the information security of distributed sensor systems and does not affect the neighboring network environment, even if hacking and cracking occur. Therefore, the BCL architecture proposed in the IoT environment can provide an optimal solution for the diversified IoT environment, because the existing block cryptographic algorithm, viz. the lightweight cryptographic algorithm, can be used.

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.271-280
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• 2010

For the next generation mobile communication system, diverse wireless network techniques such as beyond 3G LTE, WiMAX/WiBro, and next generation WLAN etc. are proceeding to the form integrated into the All-IP core network. According to this development, Beyond 3G integrated into heterogeneous wireless access technologies must support the vertical handover and network to be used of several radio networks. However, unified management of each network is demanded since it is individually serviced. Therefore, in order to solve this problem this study is introducing the theory of Common Radio Resource Management (CRRM) based on Generic Link Layer (GLL). This study designs the structure and functions to support the vertical handover and propose the vertical handover algorithm of which policy-based and MCDM are composed between LTE and WLAN systems using GLL. Finally, simulation results are presented to show the improved performance over the data throughput, handover success rate, the system service cost and handover attempt number.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.6
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• pp.880-884
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• 2001

Rumen microbiology research has undergone several evolutionary steps: the isolation and nutritional characterization of readily cultivated microbes; followed by the cloning and sequence analysis of individual genes relevant to key digestive processes; through to the use of small subunit ribosomal RNA (SSU rRNA) sequences for a cultivation-independent examination of microbial diversity. Our knowledge of rumen microbiology has expanded as a result, but the translation of this information into productive alterations of ruminal function has been rather limited. For instance, the cloning and characterization of cellulase genes in Escherichia coli has yielded some valuable information about this complex enzyme system in ruminal bacteria. SSU rRNA analyses have also confirmed that a considerable amount of the microbial diversity in the rumen is not represented in existing culture collections. However, we still have little idea of whether the key, and potentially rate-limiting, gene products and (or) microbial interactions have been identified. Technologies allowing high throughput nucleotide and protein sequence analysis have led to the emergence of two new fields of investigation, genomics and proteomics. Both disciplines can be further subdivided into functional and comparative lines of investigation. The massive accumulation of microbial DNA and protein sequence data, including complete genome sequences, is revolutionizing the way we examine microbial physiology and diversity. We describe here some examples of our use of genomics- and proteomics-based methods, to analyze the cellulase system of Ruminococcus flavefaciens FD-1 and explore the genome of Ruminococcus albus 8. At Illinois, we are using bacterial artificial chromosome (BAC) vectors to create libraries containing large (>75 kbases), contiguous segments of DNA from R. flavefaciens FD-1. Considering that every bacterium is not a candidate for whole genome sequencing, BAC libraries offer an attractive, alternative method to perform physical and functional analyses of a bacterium's genome. Our first plan is to use these BAC clones to determine whether or not cellulases and accessory genes in R. flavefaciens exist in clusters of orthologous genes (COGs). Proteomics is also being used to complement the BAC library/DNA sequencing approach. Proteins differentially expressed in response to carbon source are being identified by 2-D SDS-PAGE, followed by in-gel-digests and peptide mass mapping by MALDI-TOF Mass Spectrometry, as well as peptide sequencing by Edman degradation. At Ohio State, we have used a combination of functional proteomics, mutational analysis and differential display RT-PCR to obtain evidence suggesting that in addition to a cellulosome-like mechanism, R. albus 8 possesses other mechanisms for adhesion to plant surfaces. Genome walking on either side of these differentially expressed transcripts has also resulted in two interesting observations: i) a relatively large number of genes with no matches in the current databases and; ii) the identification of genes with a high level of sequence identity to those identified, until now, in the archaebacteria. Genomics and proteomics will also accelerate our understanding of microbial interactions, and allow a greater degree of in situ analyses in the future. The challenge is to utilize genomics and proteomics to improve our fundamental understanding of microbial physiology, diversity and ecology, and overcome constraints to ruminal function.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.9
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• pp.407-415
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• 2007

In parallel cluster computing systems, the efficiency of communication between computing nodes is one of important factors that decide overall system performance. Accordingly, many researchers have studied on high-performance inter-node communication. The recently launched multi-core processor, however. increases the importance of intra-node communication as well because the more the number of cores in a node, the more the number of parallel processes running in the same node. Though there have been studies on intra-node communications, these have limited considerations on the state-of-the-art systems. In this paper, we propose a Linux kernel module that minimizes the number of data copy by exploiting the memory mapping mechanism for high-performance intra-node communication. The proposed kernel module supports the Linux kernel version 2.6. The performance measurements over a multi-core system present that the proposed kernel module can achieve lower latency up to 62% and higher throughput up to 144% than an existing kernel module approach. In addition, the measurements reveal that the performance of intra-node communication can vary significantly based on whether the cores that run the communication processes are belong to the same processor package (i.e., sharing the L2 cache).

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.80-84
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• 2007

In this paper, the introductory study of the multi input multi output (MIMO) techniques for satellite communication systems is presented. Because of the advantage of wide coverage of satellite, it has been considered for broadcasting services and fill-in services. On the other hand, state of the art multi input multi output (MIMO) techniques such as space time code (STC) and spatial multiplexing (SM) makes the terrestrial system increase link performance and their coverage, and also increase the link throughput. For these regard, in order to satisfy the requirements of the next generation communications and coexists with terrestrial systems harmoniously, the studying about satellite MIMO techniques is necessary. In this paper, we introduce some system model and scenarios to apply MIMO technique to intermediate module repeater (IMR). The possibility of these techniques and technical requirements are also considered. Especially, Space time code is used to enhance IMRs coverage and increase the link performance, and space time multiplexing is utilized to multiplex satellite broadcasting signals with local broadcasting signal in IMR cell.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3235-3245
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• 1996

A DDFS(Direct Digital Frequency Synthesizer) used in spread spectrum communication systems must need fast switching speed, high resolution(the step size of the synthesizer), small size and low power. The chip has been designed with four parallel sine look-up table to achieve four times throughput of a single DDFS. To achieve a high processing speed DDFS chip, a 24-bit pipelined CMOS technique has been applied to the phase accumulator design. To reduce the size of the ROM, each sine ROM of the DDFS is stored 0-.pi./2 sine wave data by taking advantage of the fact that only one quadrant of the sine needs to be stored, since the sine the sine has symmetric property. And the 8 bit of phase accumulator's output are used as ROM addresses, and the 2 MSBs control the quadrants to synthesis the sine wave. To compensate the spectrum purity ty phase truncation, the DDFS use a noise shaper that structure like a phase accumlator. The system input clock is divided clock, 1/2*clock, and 1/4*clock. and the system use a low frequency(1/4*clock) except MUX block, so reduce the power consumption. A 107MHz DDFS(Direct Digital Frequency Synthesizer) implemented using 0.8.mu.m CMOS gate array technologies is presented. The synthesizer covers a bandwidth from DC to 26.5MHz in steps of 1.48Hz with a switching speed of 0.5.mu.s and a turing latency of 55 clock cycles. The DDFS synthesizes 10 bit sine waveforms with a spectral purity of -65dBc. Power consumption is 276.5mW at 40MHz and 5V.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.36-44
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• 2010

When multi-user MIMO (Multiple-Input Multiple-Output) systems utilize a sum-rate maximization (SRM) scheduler, the throughput of the systems can be enhanced. However, fairness problems may arise because users located near cell edge or experiencing poor channel conditions are less likely to be selected by the SRM scheduler. In this paper, a weighted sum-rate maximization (WSRM) scheduler is used to enhance the fairness performance of the MIMO systems. Closed-form expressions for the optimal transmit power allocation of WSRM and corresponding weighted sum-rate (WSR) are derived in the 6-sector collaborative transmission system. Using the derived results, we propose an algorithm which searches the optimal power allocation for WSRM in the 3-sector collaborative transmission system. Based on the derived closed-form expressions and the proposed algorithm, we perform computer simulations to compare performance of the WSRM scheduler and the SRM scheduler with respect to the sum-rate and the log-sum-of-average rates. We further verify that the WSRM scheduler efficiently improves fairness performance by showing the enhanced performance of average transmission rates in low percentile region.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.10-21
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• 2015

Cellular Network assisted device-to-device (D2D) communication has been growing to reduce the overload of eNodeB and mitigate the frequency shortage. However, by sharing the uplink frequency resource with the cellular network, the interference between cellular and D2D is increased. In this paper, we propose the advanced receiver based on soft decision to reduce the interference between cellular and D2D. The proposed receiver can suppress and cancel the interference by calculating the unbiased estimation value of interference signal using minimum mean square error (MMSE) or interference rejection combing (IRC) receiver. The interference signal is updated using soft information expressed by log-likelihood ratio (LLR). We perform a system level simulation based on the 20-MHz bandwidth of the 3GPP LTE-A system. Simulation results show that the proposed receiver can improve SINR, throughput and spectral efficiency compared to conventional receivers.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.19-24
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• 2016

In Long Term Evolution-Advanced (LTE-A), small cell enhancement(SCE) has been developed as a cost-effective way of supporting exponentially increasing demand of wireless data services and satisfying the user quality of service(QoS). However, due to the dense and irregular distribution of a large number of small cells, the offloading scheme should be applied in the small cell network. In this paper, we propose an user offloading scheme for SCE in LTE-Advanced system. We divide the small cells into different clusters according to the reference signal received power(RSRP) from user equipment(UE). Within a cluster, We apply the user offloading scheme with the consideration of the number of users and interference conditions. Simulation results show that proposed scheme can improve the throughput, and spectral efficiency of small cell users. Eventually, proposed scheme can improve overall cell performance.

• Journal of Internet Computing and Services
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• v.5 no.1
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• pp.67-84
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• 2004

Real-time database systems (RTDBS) are database systems whose transactions are associated with timing constraints such as deadlines. Therefore transaction needs to be completed by a certain deadline. Besides meeting timing constraints, a RTDBS needs to observe data consistency constraints as well. That is to say, unlike a conventional database system, whose main objective is to provide fast average response time, RTDBS may be evaluated based on how often transactions miss their deadline, the average lateness or tardiness of late transactions, the cost incurred in transactions missing their deadlines. Therefore, in RTDBS, transactions should be scheduled according to their criticalness and tightness of their deadlines, even If this means sacrificing fairness and system throughput, And It always must guarantee preceding process of the transaction with the higher priority. In this paper, we propose an efficient real-time scheduling algorithm (Multi-level EFDF) that alleviates problems of the existing real-time scheduling algorithms, a real-time concurrency control algorithm(2PL-FT) for firm and soft real-time transactions. And we compare the proposed 2PL F[ with AVCC in terms of the restarting ratio and the deadline missing ratio of transactions. We show through experiments that our algorithms achieve good performance over the other existing methods proposed earlier.