Browsing by Author "Keskin, R"

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    THEMATIC MAPPING OF MANISA DISTRICTS INDUSTRY INDICATORS
    Akpinar, R; Keskin, R
    Manisa and its Environments are at the top in terms of socioeconomic development. It is noteworthy that Manisa has risen from the 25th place to the 23rd place when the works of Socio-Economic Development Index Ranking of Provinces, which was prepared by the Ministry of Development with different variables in 2003 and 2011, were examined. There are 4 organized districts in total, and 7 organized industrial zones in 6 districts. Manisa Central (Yunusemre), Akhisar, Salihli and Turgutlu are the provinces that have organized industrial zones in production stage. In the manufacturing sector, more than a third of the output is derived from the electrical equipment and food sectors. Electricity equipment manufacturing is the sector that contributes the manufacturing industry production value with 19% share in sectors where concentration is high. The aim of this study is to present the spatial distribution of the Manisa industry in a mapped form with its sectoral diversity. This work; According to the industrial registry law of the Ministry of Science, Industry and Technology, the industrial enterprises have been obliged to give industrial registration documents. According to this database; For the period of 2012-2016 Manisa has sectors of industrial enterprises, names of activities, production lines, number of engineers they work with, production values. In this study; The spatial concentrations of the Manisa industry will be mapped using the spatial analysis method and the sectoral differentiations of the Manisa industry will be revealed.
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    A novel portfolio selection model based on fuzzy goal programming with different importance and priorities
    Kocadagli, O; Keskin, R
    Despite the risk return tradeoff is main concern of financial theory; the rational investment decisions requires considering many criteria simultaneously. In addition to determining a certain importance and priority among these criteria, modeling the investor behaviors in accordance with market trends provides much more realistic approach. However, the researchers mostly overlook to evaluate these concepts simultaneously. This article introduces a novel fuzzy portfolio selection model that takes into accounts the risk preferences in accordance with the market moving trends as well as the risk return tradeoff, and allows the decision makers to define a certain importance and priority among their objectives. To construct this model, firstly the portfolio return, risk and beta coefficient are assumed as main objectives including the possibilistic uncertainties. To define possibilistic uncertainty, the specific fuzzy membership functions are constituted for these objectives with respect to the risk preferences of investors and market moving trends. By means of the fuzzy goal programming techniques, a novel portfolio selection model is developed using these specific fuzzy membership functions. In the application section, three investment terms are examined in the Istanbul Stock Exchange National 30 Index. While ISE30 index has the upward (bullish) and the downward (bearish) moving trends in the first two implementations, the third implementation includes a scenario in which the investors desire to chase the ISE30 index. In the analyses, the proposed model is compared with the classical Mean Variance, Mean-Absolute-Deviation and Maxmin models in terms of their portfolio returns based on the selling prices in the test periods. As a result, the proposed model gives superior performance than the classical models because it takes into account the investor preferences in accordance with market moving trend. (C) 2015 Elsevier Ltd. All rights reserved.
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    A novel fuzzy goal programming approach with preemtive structure for optimal investment decisions
    Keskin, R; Kocadagli, O; Cinemre, N
    In this article, a novel portfolio selection model is proposed. This model is essentially based on the fuzzy goal programming with preemptive structure. In order to construct this model; the portfolio risk, the return levels and the beta coefficient introduced in the Capital Asset Pricing Model are considered as the fuzzy goals, and then a preemptive priority is defined among them. In accordance with the market moving trends, the different portfolio selection models are constituted for different types of investor behaviors. This model not only takes into account the different investor strategies with respect to the market moving trends, but provides also a reasonable diversification for a portfolio in terms of the risk - return tradeoff together with beta coefficient. In the application sections, the two different periods having the upward and the downward moving trends in the Istanbul Stock Exchange National 30 Index are handled separately, then the optimal portfolios are determined using the proposed portfolio selection model accordance with different investment strategies. Finally, the optimal portfolios are compared in terms of their return performances based on the selling prices in the test periods.