• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.5803-5819
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• 2017

In this paper, we proposed a contract theory based cooperative spectrum sharing scheme with joint power and bandwidth optimization under asymmetric information, where the primary user (PU) does not know the secondary users' (SUs) private information. To improve performance, PU needs to provide incentives to stimulate nearby SUs to help forward its signal. By using contract theory, PU and SUs' negotiations are modeled as a labor market. PU and SUs act as the employer and employees, respectively. Specifically, SUs provide labor (i.e. the relay power, which can be used for forwarding PU's signal) in exchange for the reward (i.e. the spectrum access bandwidth which can be used for transmitting their own signals). PU needs to overcome a challenge how to balance the relationship between contributions and incentives for the SUs. We study the optimal contract design which consists of relay power and spectrum access bandwidth allocation. We show that the most efficient SUs will be hired by the PU to attend the cooperative communication. PU can achieve the same maximum utility as in the symmetric information scenario. Simulation results confirm that the utility of PU is significantly enhanced with our proposed cooperative spectrum sharing scheme.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.3
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• pp.129-138
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• 2014

After global economic crisis, China has become one of the two pillars in the global economies and the country contributing to the Korean economy. Nevertheless, the research on Chinese financial market, particularly capital market, is rare to date. This study examined the growth enterprise market that emergedat the Shenzhen stock exchange and made comparative analysis on before and after listing for the Chinese small and medium sized firms and venture firms. The listing requirements at the Chinese growth enterprise market for the technologically innovative venture firms and fast-growing small and medium sized firms with financing purpose were more alleviated than the main board of Shenzhen stock exchange. Moreover, the listing procedures are simplified as well. Accordingly, many Chinese enterprises tend to list and the competition for listing is also intense. In particular, with the 36 initially listed firms at growth enterprise market as the research target, the investigation for the business performance before and after listing reveals that the three indexes including return on common equity, debt ratio and operating profit growth rate dropped dramatically for most all the firms. That is, the profitability and growth for the venture firms and small and medium sized firms listed on the Chinese growth enterprise market decreased rapidly after going public, only the stability improved due to the great financing. Taking a step forward, this phenomenon may result from the exaggerated reporting for the business performance before listing with the purpose of going public by the venture firms and small and medium sized firms. Thus, Chinese Securities Regulatory Commission should strengthen the accounting evaluation standard and regulation for the listing firms before going public. In addition, strict sanctions should be imposed on the firms with fraudulent accounting to establish healthy capital market.

• International Commerce and Information Review
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• v.14 no.4
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• pp.61-88
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• 2012

Korea exported the passenger cars(HS 8703) such as key export item 41billion dollars in 2011. But the Korea's representative enterprises which bound forward in the global markets, have a tough time in the Japanese markets alone, and especially, they hardly sell key items such as automobiles. Japan is the third largest automobile market sold annually 5 millions, despite its long-term depression. At this time of point, analyzing the competition structure of the automobile market and proposing the strategies of the Korean enterprises's export to Japan would be a great academic contribution. This study analyzed the Japanese automobile market by the method of upper enterprises' Concentration Ratio($CR_k$) based on J. S. Bain's SCP paradigm and the literature study on the characteristics of the Japanese market by Itami Hiroyuki. As a result, in the Japanese automobile market, it is very likely that there exist market dominating enterprises, but at the same time, the movement of change also could be grasped between Japanese car makers. Accordingly, the cross-leveraging distribution strategy, brand strategy and Japan specification(designed for Japan) development strategy of the Korean enterprises' export to Japan which can respond to the change of the Japanese automobile markets were proposed.

• Journal of Internet Computing and Services
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• v.23 no.4
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• pp.45-55
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• 2022

The size of the cryptocurrency market is growing. For example, market capitalization of bitcoin exceeded 500 trillion won. Accordingly, many studies have been conducted to predict the price of cryptocurrency, and most of them have similar methodology of predicting stock prices. However, unlike stock price predictions, machine learning become best model in cryptocurrency price predictions, conceptually cryptocurrency has no passive income from ownership, and statistically, cryptocurrency has at least three times higher liquidity than stocks. Thats why we argue that a methodology different from stock price prediction should be applied to cryptocurrency price prediction studies. We propose Reverse Walk-forward Validation (RWFV), which modifies Walk-forward Validation (WFV). Unlike WFV, RWFV measures accuracy for Validation by pinning the Validation dataset directly in front of the Test dataset in time series, and gradually increasing the size of the Training dataset in front of it in time series. Train data were cut according to the size of the Train dataset with the highest accuracy among all measured Validation accuracy, and then combined with Validation data to measure the accuracy of the Test data. Logistic regression analysis and Support Vector Machine (SVM) were used as the analysis model, and various algorithms and parameters such as L1, L2, rbf, and poly were applied for the reliability of our proposed RWFV. As a result, it was confirmed that all analysis models showed improved accuracy compared to existing studies, and on average, the accuracy increased by 1.23%p. This is a significant improvement in accuracy, given that most of the accuracy of cryptocurrency price prediction remains between 50% and 60% through previous studies.

• Journal of Korea Trade
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• v.23 no.7
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• pp.34-44
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• 2019

Purpose - The purpose of this study is to present what the port of Pyeongtaek, the hub of Korean trade with China, should improve in the current situation, wherein the e-commerce trade volume between Korea and China is increasing due to the development of online technology. Design/methodology - In this study, through prior research and expert interviews on e-commerce and port activation between borders, we derived the main improvement factors for 1) Administration and Systems, 2) Facilities, 3) Transport, and 4) Manpower, and selected 12 detailed variables for the major improvement factors. To identify the relative importance of the major improvement factors, the Analytic Hierarchy Process (AHP) method was applied, and a survey was conducted among 15 related experts. Findings - As a result, among the 12 detailed variables, Composition of Association (0.267) was the first factor to be improved, followed by Incentive Support (0.143) and E-Commerce Cluster (0.131). Based on these analyses, the main implications of this study are, first, in the current situation where the cross-border e-commerce market is growing, Pyeongtaek Port needs to form a consultative body among the government, local governments, and related businesses in connection with cross-border e-commerce and develop various support policies for the e-commerce market. Second, it will have to be able to provide differentiated services from competing ports by establishing e-commerce market-oriented clusters. Originality/value - In existing related studies, various improvements were presented to revitalize trade in line with the growth of the cross-border e-commerce market. However, with regard to most cross-border e-commerce businesses, one-dimensional improvement measures, such as improvement of payment systems, improvement of customs clearance services, and promotion of human resources, are presented in a piecemeal manner. In other words, none of the studies have proposed the importance and priority of each measure in terms of both the forward-looking and efficient allocation of resources, which is the purpose of this study. Therefore, this study contributed politically, practically, and academically by presenting countermeasures for ports to revitalize cross-border e-commerce and presenting strategic priorities using quantitative analysis methods.

• Journal of the Korea Institute of Building Construction
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• v.8 no.2
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• pp.121-129
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• 2008

Domestic exoteric construction market by opening of world construction market with recent FTA of rapidly change. On these time, need quality increase of construction to possess government official and international competitiveness of customer satisfaction by offering consumer building of good quality. Therefore, must establish direction to inspects and must advance forward formation government official's present actual conditions for building company's QI. This study is as following if summarize studying result of formation government official to improve quality in construction spot. First, formation's CEO will for QI need side improvement the formation government official enemy by important thing. Second, at checking activity and systematic action that participate of responsible persons cooperation enterprise space-time by complete charge department organization should be achieved. Third, complete charge department for quality control operation large size construction firm substantially formation Organizational well operate, but heavy hydrogen building company was construed by greatly unprepared misgovernment. AHP analysis result complete charge department is serious necessity, and the CEO under direct control organizational structure was construed by thing which can bring excellent effect in operation management side of quality business side and formation. Therefore, heavy hydrogen building company should does to occupy competitive power high position with tissue at active quality complete charge deputy.

• Journal of Electrical Engineering and Technology
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• v.6 no.4
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• pp.431-438
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• 2011

To ensure that equipment outages do not directly impact the reliability of the ISO-controlled grid, market participants request permission and receive approval for planned outages from the independent system operator (ISO) in competitive electricity markets. In the face of major generation outages, the ISO will make a critical decision as regards the scheduling of the essential maintenance for myriads of generating units over a fixed planning horizon in accordance with security and adequacy assessments. Mainly, we are concerned with a fundamental framework for ISO's maintenance coordination in order to determine precedence of conflicting outages. Simulated annealing, a powerful, general-purpose optimization methodology suitable for real combinatorial search problems, is used. Generally, the ISO will put forward its best effort to adjust individual generator maintenance schedules according to the time preferences of each power generator (GENCO) by taking advantage of several factors such as installed capacity and relative weightings assigned to the GENCOs. Thus, computer testing on a four-GENCO model is conducted to demonstrate the effectiveness of the proposed method and the applicability of the solution scheme to large-scale maintenance scheduling coordination problems.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.2
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• pp.74-81
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• 2012

The purpose of this study provides the theoretical model for protecting the economic and social loss from the current alternative fuel vehicle which is developed without compatibility and senseless one's own through verifying the statistical significant by method of measuring analysis. The market scale of alternative fuel vehicle depends on customer's and station's expectation about the number of potential vehicle users. It is very difficult for vehicle manufacturer to make a decision on the standard alternative fuel vehicle as it might reduce profit and market share. Accordingly, the development of alternative fuel vehicle should have manufacturer confident on the potential profit in the future. Moreover, if we decide to use the non-standard fuel after we started to use the standard fuel, it would take a huge cost comparing with starting to use the standard fuel only. As a result, once one of companies starts to provide the non-standard fuel service, it is getting more difficult to use the standard fuel going forward. Consequently, we may review the possibility of choice on the standard fuel before the vehicle manufacturer starts service with non-standard fuel.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.43-49
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• 2003

Low-temperature polysilicon (LTPS) technology has continued to mature with the passing of each year since LTPS mass production began. The integration of complex circuits has become possible with advances in microprocessing, leading to the realization of panels with highly advanced functions. At the same time, efforts have been made to meet market demands for lower costs, thereby boosting competitive strength. Today, LTPS-TFT LCDs have become standard equipment for the monitors of digital still cameras, and inroads are being made into the massive cellular phone market. Micro displays such as electronic viewfinders, which were previously only possible with high-temperature polysilicon technology, can now also be made with LTPS, thus expanding the scope of the technology. AMOLED displays using the LTPS-TFT as a back plane are also approaching the stage of industrialization. The hidden potential for the OLED to replace the familiar LCD has prompted Widespread anticipation for this emerging technology. This paper reflects on the history of LTPS technology, then looks forward to its future prospects and suggests a variety of potential fields of application.

• ETRI Journal
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• v.34 no.4
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• pp.602-612
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• 2012

It is becoming increasingly difficult to identify promising technologies due to the influx of new technologies and the high level of complexity involved in many of these technologies. Identifying promising information and communications technology (ICT)-based converging technologies holds the key to finding new sources of economic growth and forward momentum. The goal of this study is to identify cutting-edge ICT-based converging technologies by examining the latest trends in the US patent market. Analyzing the US patent market, the most competitive of such markets in the world, can yield certain clues about which of the ICT-based converging technologies may be the next revolutionary technologies. For a classification of these technologies, this study follows the International Patent Classification system. As for ICT, there are 58 related fields at the subclass level and 831 fields at the main-group level. For emerging and converging technologies, there are 75 at the main-group level. From these technologies, a final selection for cutting-edge ICT-based converging technologies is made using a composite index reflecting the converging coefficient, emerging coefficient, and technology impact index.