• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4623-4643
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• 2015

This paper considers physical-layer security protocols in multicast cognitive radio (CR) networks. In particular, we propose dual-hop cooperative decode-and-forward (DF) and randomize-and-forward (RF) schemes using partial relay selection method to enhance secrecy performance for secondary networks. In the DF protocol, the secondary relay would use same codebook with the secondary source to forward the source's signals to the secondary destination. Hence, the secondary eavesdropper can employ either maximal-ratio combining (MRC) or selection combining (SC) to combine signals received from the source and the selected relay. In RF protocol, different codebooks are used by the source and the relay to forward the source message secretly. For each scheme, we derive exact and asymptotic closed-form expressions of secrecy outage probability (SOP), non-zero secrecy capacity probability (NzSCP) in both independent and identically distributed (i.i.d.) and independent but non-identically distributed (i.n.i.d.) networks. Moreover, we also give a unified formula in an integral form for average secrecy capacity (ASC). Finally, our derivations are then validated by Monte-Carlo simulations.

• Journal of Communications and Networks
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• v.13 no.3
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• pp.240-249
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• 2011

Cooperative diversity protocols have attracted a great deal of attention since they are thought to be capable of providing diversity multiplexing tradeoff among single antenna wireless devices. In the high signal-to-noise ratio (SNR) region, cooperation is rarely required; hence, the spectral efficiency of the cooperative protocol can be improved by applying a proper cooperation selection technique. In this paper, we present a simple "cooperation selection" technique based on instantaneous channel measurement to improve the spectral efficiency of cooperative protocols. We show that the same instantaneous channel measurement can also be used for relay selection. In this paper two protocols are proposed-proactive and reactive; the selection of one of these protocols depends on whether the decision of cooperation selection is made before or after the transmission of the source. These protocols can successfully select cooperation along with the best relay from a set of available M relays. If the instantaneous source-to-destination channel is strong enough to support the system requirements, then the source simply transmits to the destination as a noncooperative direct transmission; otherwise, a cooperative transmission with the help of the selected best relay is chosen by the system. Analysis and simulation results show that these protocols can achieve higher order diversity with improved spectral efficiency, i.e., a higher diversity-multiplexing tradeoff in a slow-fading environment.

• Journal of the military operations research society of Korea
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• v.35 no.1
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• pp.63-82
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• 2009

The purpose of this study is to analyze the problems of current rules and regulations on the source selection for weapon system in defense acquisition project and suggest several techniques to ensure objectivity and fairness. As an application example, Helicopter source selection was presented. It was analyzed and compared through technique application and strength and weakness analysis of AHP, PROMETHEE and Attribute Transformation. The decision making techniques which make all conditions satisfactory in all situations are nonexistent. Thus, it is estimated that we can maintain the objectivity in the source selection of weapon systems by applying suitable decision making techniques in accordance with the patterns of evaluation item.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.272-277
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• 2001

In this paper, we describe a new method for selecting information sources in a distributed environment. Recently, there has been much research on distributed information retrieval, that is information retrieval (IR) based on a multi-database model in which the existence of multiple sources is modeled explicitly. In distributed IR, a method is needed that would enable selecting appropriate sources for users\` queries. Most existing methods use statistical data such as document frequency. These methods may select inappropriate ate sources if a query contains polysemous words. In this paper, we describe an information-source selection method using two types of thesaurus. One is a thesaurus automatically constructed from documents in a source. The other is a hand-crafted general-purpose thesaurus(e.g. WordNet). Terms used in documents in a source differ from one another and the meanings of a term differ depending on th situation in which the term is used. The difference is a characteristic of the source. In our method, the meanings of a term are distinguished between by the relationship between the term and other terms, and the relationship appear in the co-occurrence-based thesaurus. In this paper, we describe an algorithm for evaluating a usefulness of a source for a query based on a thesaurus. For a practical application of our method, we have developed Papits, a multi-agent-based in formation sharing system. An experiment of selection shows that our method is effective for selecting appropriate sources.

• Journal of Digital Contents Society
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• v.6 no.4
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• pp.229-234
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• 2005

Companies are attempting application of open source software development approach method as new alternatives to solve roiling pints of the existing software developments such as quality of software, development speeds and cost. On the other hand, various analyses about open source software were performed, but concrete procedures or the results of suitable study about a way to utilize open source for a software development in actual industry are not yet. This study presented process model for identification, valuation selection of suitable open source, and modification application or commercializing.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.320-326
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• 2016

In existing literature on multiple-input multiple-output (MIMO) relaying communication systems, antenna selection is often implemented by maximizing the channel capacity or the output single-to-noise ratio (SNR). In this paper, we propose an energy-efficient low-complexity antenna selection scheme for MIMO relaying communication systems. The proposed algorithm is based on beamforming and maximizing the Frobenius norm to jointly optimize the transmit power, number of active antennas, and antenna subsets at the source, relaying and destination. We maximize the energy efficiency between the link of source to relay and the link of relay to destination to obtain the maximum energy efficiency of the system, subject to the SNR constraint. Compared to existing antenna selection methods forMIMO relaying communication systems, simulation results demonstrate that the proposed method can save more power in term of energy efficiency, while having lower computational complexity.

• Journal of Distribution Science
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• v.14 no.11
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• pp.117-128
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• 2016

Purpose - In order to collect information needed for the establishment of more effective marketing strategies of on-line purchasing agent services targeting Chinese consumers, the study investigated the relationship among Chinese selection criteria. They included fashion products, use of information source, and satisfaction with on-line purchasing agent services. The study also identified the differences in the Chinese selection criteria of fashion products, use of information source, and the satisfaction level with on-line purchasing agent services according to their age and gender. Research design, data, and methodology - The study was implemented through a normative-descriptive survey method using a self-administered questionnaire. Data were collected from February 9 to 28, 2016, and analyzed by factor analysis, ANOVA and Duncan test, t-test, and multiple regression analysis. Results - Differences were found in selection criteria of fashion products and use of information sources among groups. Thirty's age group was concerned about price/brand more than the twenty's were. Twenty's were concerned about practicality/quality of the products more than the thirty's. Hallyu/broadcasting was used by men more than by women as an information source of Korean fashion. SNS/WOM(word of mouth) was used more by women than by man. Twenty's showed lower level of satisfaction with customer services/credibility than other factors. The thirty's showed lower level of satisfaction with informational role of the service than other factors. Those who utilize each type of fashion information source more showed higher satisfaction level with on-line purchasing agent service of Korean fashion products.. In general, according to the selection criteria and use of information, there were differences in satisfaction with on-line purchasing agent service of Korean fashion products. Conclusions - Considering the findings of the study, as well as age, gender, selection criteria and use of information source, Chinese consumers could be used as a criteria of market segmentation for on-line purchasing agent services of Korean fashion products. The results manifested that there is a need to differentiate marketing strategies according to the satisfaction levels with each satisfaction factors of on-line purchasing agent service of Korean fashion products.

• Journal of Korea Multimedia Society
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• v.18 no.4
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• pp.533-540
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• 2015

We study relay selection in decode-and-forward (DF)-based relay networks consisting of a source, a destination, an eavesdropper, and multiple relays, where each terminal has a single antenna and operates in a half-duplex mode. In these networks, it is desirable to protect the confidential message from the source to the destination against the eavesdropper with the help of a single selected relay. Specifically, we begin by investigating DF-based networks for the scenario instantaneous signal-to-noise ratios (SNRs) related to the eavesdropper are available. For the scenario, we propose relay selection to maximize the secrecy rate of DF-based networks with and without direct-paths, and we derive the exact secrecy outage probabilities in closed-form.

• Journal of Environmental Impact Assessment
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• v.20 no.6
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• pp.857-866
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• 2011

This research categorized EIA target highways into following three types in order to minimize non-point source pollution from highway runoff. 1. Big drainage basin. 2. Small drainage basin. 3. Bridge section. The Natural, Filter and Swirl-Type devices were evaluated in terms of removal efficiency of TSS, BOD, COD, T-N, T-P, compatibility of site selection, economic feasibility, and maintenance convenience through which the final BMP was selected. According to the removal efficiency result, the area of Big and Small Drainage basin and bridge section had higher removal efficiency with natural facility than that of the Filter or Swirl-Type device. To make appropriate selection of highways'BMP for non-point source pollution, this study will aim to contribute to building more environmentally friendly highways by proposing the selection process that is made of 5 stages. 1. Selecting the target drainage basin. 2. Selecting the land for the mitigation facility. 3. Analysing the ease of maintenance. 4. Technically evaluating each installation. 5. Evaluating the effective implementation methods.

• Journal of the Korean Solar Energy Society
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• v.25 no.2
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• pp.63-69
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• 2005

This study is the survey of a transition procedure of building services systems(heat source, HVAC, water supply) through the survey of existing office buildings, building design documents. The preference & major consideration of system selection is the engineer's opinions. The results of this survey can be used in selection of building services system design. In this survey, "Hot & cold water generator system" and "single duct CAV+FCU system", "Elevated water tank system" are selected. The most important consideration in system selection is the energy saving in heat source system, and comfort in HVAC system, and water pressure in water supply system. They prefer "steam boiler+absorption chiller system" for heat source system, "steam boiler+ice thermal storage system", "hot & cold water generator system", "district heating+absorption chiller system" : "single duct CAV+FCU system" and "single duct VAV+convector system" for HVAC system: and "booster pump system" for water supply system.