• Title/Summary/Keyword: multiple chains

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An efficient cloud security scheme for multiple users (다중 사용자를 위한 효율적인 클라우드 보안 기법)

  • Jeong, Yoon-Su
    • Journal of Convergence for Information Technology
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    • v.8 no.2
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    • pp.77-82
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    • 2018
  • Recently, as cloud services become popular with general users, users' information is freely transmitted and received among the information used in the cloud environment, so security problems related to user information disclosure are occurring. we propose a method to secure personal information of multiple users by making personal information stored in the cloud server and a key for accessing the shared information so that the privacy information of the multi users using the cloud service can be prevented in advance do. The first key used in the proposed scheme is a key for accessing the user 's personal information, and is used to operate the information related to the personal information in the form of a multi - layer. The second key is the key to accessing information that is open to other users than to personal information, and is necessary to associate with other users of the cloud. The proposed scheme is constructed to anonymize personal information with multiple hash chains to process multiple kinds of information used in the cloud environment. As a result of the performance evaluation, the proposed method works by allowing third parties to safely access and process the personal information of multiple users processed by the multi - type structure, resulting in a reduction of the personal information management cost by 13.4%. The efficiency of the proposed method is 19.5% higher than that of the existing method.

Degrees of Freedom for MIMO Z-Interference Channels with Reconfigurable Antennas in the Absence of CSIT (송신단 채널 정보가 없는 재구성 안테나를 사용한 다중입출력 Z-간섭 채널에서의 자유도)

  • Yang, Heecheol;Lee, Jungwoo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.2
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    • pp.291-298
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    • 2017
  • In this paper, we derive the achievable degrees of freedom (DoF) for multiple-input multiple-output (MIMO) Z-interference channels (Z-IC) with reconfigurable antennas at the receivers, assuming that channel state information is not available at the transmitters. We propose a new linear scheme to align interfering signals and to decode desired signals through the designed preset mode switching pattern of reconfigurable antennas at the receivers. The key idea of our scheme is to use interfering signals as a side information at the interfered receiver by being silent at the corresponding transmitter during some time slots. Consequently, it is shown that the reconfigurable antennas at the receivers can bring a DoF gain if the number of preset modes is greater than the number of RF chains at the receivers.

Widely-Linear Beamforming and RF Impairment Suppression in Massive Antenna Arrays

  • Hakkarainen, Aki;Werner, Janis;Dandekar, Kapil R.;Valkama, Mikko
    • Journal of Communications and Networks
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    • v.15 no.4
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    • pp.383-397
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    • 2013
  • In this paper, the sensitivity of massive antenna arrays and digital beamforming to radio frequency (RF) chain in-phase quadrature-phase (I/Q) imbalance is studied and analyzed. The analysis shows that massive antenna arrays are increasingly sensitive to such RF chain imperfections, corrupting heavily the radiation pattern and beamforming capabilities. Motivated by this, novel RF-aware digital beamforming methods are then developed for automatically suppressing the unwanted effects of the RF I/Q imbalance without separate calibration loops in all individual receiver branches. More specifically, the paper covers closed-form analysis for signal processing properties as well as the associated radiation and beamforming properties of massive antenna arrays under both systematic and random RF I/Q imbalances. All analysis and derivations in this paper assume ideal signals to be circular. The well-known minimum variance distortionless response (MVDR) beamformer and a widely-linear (WL) extension of it, called WL-MVDR, are analyzed in detail from the RF imperfection perspective, in terms of interference attenuation and beamsteering. The optimum RF-aware WL-MVDR beamforming solution is formulated and shown to efficiently suppress the RF imperfections. Based on the obtained results, the developed solutions and in particular the RF-aware WL-MVDR method can provide efficient beamsteering and interference suppressing characteristics, despite of the imperfections in the RF circuits. This is seen critical especially in the massive antenna array context where the cost-efficiency of individual RF chains is emphasized.

Hybrid Transmitter Design for Massive MIMO Systems (대용량 MIMO 시스템을 위한 하이브리드 송신기 설계)

  • Seo, Bangwon
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.22 no.3
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    • pp.49-55
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    • 2022
  • In the next generation mobile communication systems, hybrid massive multiple-input multiple output (MIMO) can be used to highly improve an achievable rate without increasing the number of RF chains. Recently, successive-interference-cancellation (SIC) based hybrid precoder design scheme was proposed to reduce the complexity. However, since this scheme uses simple diagonal matrix for baseband precoding, it cannot solve an interference problem between the transmitted streams. Also, there is a limitation for improving the data rate because of the use of one phase shifter for analog precoding. To solve these problems, in this paper we propose a digital precoding based on the SVD of the effective channel and an analog precoding using two phase shifters. Through simulation, we show that the proposed scheme has better achievable rate and SINR performances than the conventional one.

A Hierarchical Model for Mobile Ad Hoc Network Performability Assessment

  • Zhang, Shuo;Huang, Ning;Sun, Xiaolei;Zhang, Yue
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.8
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    • pp.3602-3620
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    • 2016
  • Dynamic topology is one of the main influence factors on network performability. However, it was always ignored by the traditional network performability assessment methods when analyzing large-scale mobile ad hoc networks (MANETs) because of the state explosion problem. In this paper, we address this problem from the perspective of complex network. A two-layer hierarchical modeling approach is proposed for MANETs performability assessment, which can take both the dynamic topology and multi-state nodes into consideration. The lower level is described by Markov reward chains (MRC) to capture the multiple states of the nodes. The upper level is modeled as a small-world network to capture the characteristic path length based on different mobility and propagation models. The hierarchical model can promote the MRC of nodes into a state matrix of the whole network, which can avoid the state explosion in large-scale networks assessment from the perspective of complex network. Through the contrast experiments with OPNET simulation based on specific cases, the method proposed in this paper shows satisfactory performance on accuracy and efficiency.

Metastatic Mammary Gland Adenocarcinoma in a Tiger (Panthera tigris altica) (백호에서의 전이성 유선암종)

  • Shin, Nam-Sik;Kwon, Soo-Wahn;Kim, Yang-Beum;Kim, Bang-Hyun;Oh, Sang-Yeon;Kim, Dae-yong
    • Korean Journal of Veterinary Research
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    • v.42 no.3
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    • pp.389-392
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    • 2002
  • A 17-year-old female tiger (Panthera tigris altica) was found dead after suffering from continuously growing mass at the right mammary gland area. At necropsy, a firm tan mass approximately 25 cm in diameter was noted at the ventral abdomen. The mass was not fixed to the adjacent tissue and mottled tan to red on cut sections. Chains of similar nodules ranging from 2 to 5 cm in diameter were also present along the right mammary glands region. Histologically, the neoplastic masses consisted of lobules that were filled with pleomorphic neoplastic cells and separated by fibrious conntective tissue. The neoplastic cells have hyperchromatic nuclei with prominent nucleolus and moderate amount of cytoplasm. The degree of mitosis was high. Multiple areas of necrosis, hemorrhage, mineralization and tumor emboli were also noted. Metastasis to the regional lymph nodes, lung, liver, spleen, kidney, and adrenal gland were observed. Based on the gross and histopathologic examinations, a diagnosis of lobular type metastatic mammary gland carcinoma was made.

Retail Changes in the Optical Sector : Empirical evidence from Italian Retailers (광학분야에서 소매 판매의 변화 ; 이태리 소매의 경험적 증거)

  • Padova, Maria Angela;Kim, Douk-Hoon
    • Journal of Korean Ophthalmic Optics Society
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    • v.8 no.2
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    • pp.153-162
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    • 2003
  • The transformation of the Italian retailing has permitted, in the last ten years, a quick modification of the strategic groups' weight at a distributive level. Such change regards the redesign of the competitive assets that sees as protagonist both the main foreign big multiple chains and the Italian retailing, characterized by small dependent enterprises. The analysis is focused on the solutions that independent retailers are adopting in order to strengthen their competitive ability in relation to the aforementioned prospective entrance of foreign distributors in the domestic market. In particular, the most commonly adopted strategic alternative are analysed, in an attempt to characterize the development models that can emerge. The paper presents a case of possible successful solution adopted by some independent retailers for a competitiveness recovery without sacrificing the enterprise's property and autonomy.

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Analysis of Joint Transmit and Receive Antenna Selection in CPM MIMO Systems

  • Lei, Guowei;Liu, Yuanan;Xiao, Xuefang
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.3
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    • pp.1425-1440
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    • 2017
  • In wireless communications, antenna selection (AS) is a widely used method for reducing comparable cost of multiple RF chains in MIMO systems. As is well known, most of literatures on combining AS with MIMO techniques concern linear modulations such as phase shift keying (PSK) and quadrature amplitude modulation (QAM). The combination of CPM and MIMO has been considered an optimal choice that can improve its capacity without loss of power and spectrum efficiency. The aim of this paper is to investigate joint transmit and receive antenna selection (JTRAS) in CPM MIMO systems. Specifically, modified incremental and decremental JTRAS algorithms are proposed to adapt to arbitrary number of selected transmit or receive antennas. The computational complexity of several JTRAS algorithms is analyzed from the perspective of channel capacity. As a comparison, the performances of bit error rate (BER) and spectral efficiency are evaluated via simulations. Moreover, computational complexity of the JTRAS algorithms is simulated in the end. It is inferred from discussions that both incremental JTRAS and decremental JTRAS perform close to optimal JTRAS in BER and spectral efficiency. In the sense of practical scenarios, adaptive JTRAS can be employed to well tradeoff performance and computational complexity.

Application of an Efficient Method for Isolation of Mitochondria from Biological Samples

  • Jun, Jin Hyun;Kim, Jihyun;Kim, Kyung Tae;Sung, Ho Joong
    • Biomedical Science Letters
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    • v.20 no.3
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    • pp.180-184
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    • 2014
  • Mitochondria play a crucial role in many essential biological events by way of the electron transport chains and intermembrane proteins that they contain. Abnormalities in the mitochondria are strongly correlated with the development of diseases such as atherosclerosis, cancer, and diabetes. However, the study of mitochondria has been referred to as 'labor-intensive' because of the difficulty in isolating the organelles from their various sources, which can include cultured cells and tissues. Multiple companies provide mitochondria isolation kits, and it is possible for investigators to use different kits and apply different protocols depending on the source of the mitochondria. Therefore, we focused on producing an isolation buffer that could be applied to both cultured cells and tissues, and optimized an isolation protocol that could be used with both. Specifically, we adjusted the buffer condition that can be applied to human cervical cancer cells, fibroblasts, and tissues such as mouse liver and spleen. We also optimized the protocol to improve the efficacy and efficiency of the steps involved in the isolation of mitochondria. These methodological improvements may contribute to advanced research by allowing investigators to overcome the difficulties involved in isolation of mitochondria from biological samples.

Adaptive Inventory Control Models in a Supply Chain with Nonstationary Customer Demand (비안정적인 고객수요를 갖는 공급사슬에서의 적응형 재고관리 모델)

  • Baek, Jun-Geol;Kim, Chang Ouk;Jun, Jin
    • Journal of Korean Institute of Industrial Engineers
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    • v.31 no.2
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    • pp.106-119
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    • 2005
  • Uncertainties inherent in customer demand patterns make it difficult for supply chains to achieve just-in-time inventory replenishment, resulting in loosing sales opportunity or keeping excessive chain wide inventories. In this paper, we propose two intelligent adaptive inventory control models for a supply chain consisting of one supplier and multiple retailers, with the assumption of information sharing. The inventory control parameters of the supplier and retailers are order placement time to an outside source and reorder points in terms of inventory position, respectively. Unlike most extant inventory control approaches, modeling the uncertainty of customer demand as a stationary statistical distribution is not necessary in these models. Instead, using a reinforcement learning technique, the control parameters are designed to adaptively change as customer demand patterns change. A simulation based experiment was performed to compare the performance of the inventory control models.