• Journal of Institute of Control, Robotics and Systems
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• v.11 no.7
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• pp.644-650
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• 2005

The expected positioning accuracies of civil users utilizing modernized GPS and Galileo are derived using the error analysis in this paper. Since, in general, the performance of DLL, PLL and FLL is proportional to chip lengths and wavelengths, the positioning accuracies from various measurements of modernized GPS and Galileo are derived as function of chip length and wavelength. These results are compared with that from GPS Ll measurement. In absolute positioning, compared to GPS C/A code only case, more than 17 times performance improvement is expected when all civil code signals of modernized GPS and Galileo (L1, L2, L5, E1, E5A and E5B) are used. In relative positioning, compared to GPS L1 carrier phase only case, more than 2 times performance improvement is expected when all civil signals of modernized GPS and Calileo are used. Furthermore, the relationship between GDOP and RGDOP in single frequency case is expanded to general case where multiple frequencies and both code and carrier phase measurements are used.

• The Korean Journal of Financial Management
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• v.24 no.3
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• pp.153-186
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• 2007

It is well known that the distributional properties of financial asset returns exhibit fatter-tails and skewer-mean than the assumption of normal distribution. The correct assumption of return distribution might improve the estimated performance of the Value-at-Risk(VaR) models in financial markets. In this paper, we estimate and compare the VaR performance using the RiskMetrics, GARCH and FIGARCH models based on the normal and skewed-Student-t distributions in two daily returns of the Korean Composite Stock Index(KOSPI) and Korean Won-US Dollar(KRW-USD) exchange rate. We also perform the expected shortfall to assess the size of expected loss in terms of the estimation of the empirical failure rate. From the results of empirical VaR analysis, it is found that the presence of long memory in the volatility of sample returns is not an important in estimating an accurate VaR performance. However, it is more important to consider a model with skewed-Student-t distribution innovation in determining better VaR. In short, the appropriate assumption of return distribution provides more accurate VaR models for the portfolio managers and investors.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.9 no.3
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• pp.97-105
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• 2014

The purpose of this study is to identify the expected effects of LOHAS certification on business management performance. LOHAS certification which Korean Standards Association adopts and operates, contributes to improve the quality of healthy and happy life through the spread of eco-friendly and social responsible products and supports company's continuous growth and development through product value and image enhancement. The object of certification is divided into products and non products which is like services and space. In this study, empirical method using Questionnaire survey is used to look through the expected effect of LOHAS certification on business management performance focused on the manufacturing companies which acquired LOHAS certification.

• Journal of the Korean Statistical Society
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• v.25 no.3
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• pp.445-456
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• 1996

In this paper, we derive unbiased estimators for the sensitivities of expected performance measures in a Markov renewal process. We restrict our derivation to the performance measures during a busy cycle and apply smoothed perturbation analysis method to find those esti-mators. The results show all the terms in the derived estimators can be obtained from a single sample path.

• Architectural research
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• v.15 no.1
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• pp.9-15
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• 2013

Effects of physical attributes of workstation enclosures on the performance of office workers with different difficult levels of office tasks and moods are presented. Performance scores in complex tasks were expected to increase with greater workstation enclosures while those in simple tasks would be the same. Mood ratings were expected to be higher in lower workstation enclosures. Performance of 102 college students on ambient office sounds (45 dBA) with office tasks were measured for 100 minutes under three different workplace enclosures: (1) four foot partitions on two sides; (2) six foot partitions on three sides; and (3) a fully enclosed workstation with eight foot partitions. The tasks were to memorize a paragraph with 130 words (complex task) and to search phone numbers (simple task). The complex task performance in the fully enclosed workstation was increased compared to that in the workstation with four foot partitions (p < 0.001) and to that in the workstation with six foot partitions (p < 0.05). However, occupants in the fully enclosed workstation with office sounds without speech generally gave higher mood ratings. It indicates that closed individual offices may offer important contributions to collaborative work as well as individual productivity. These findings would help design community revise open plan design to increase collaboration among office workers.

• Journal of Information Technology Applications and Management
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• v.17 no.3
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• pp.83-97
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• 2010

The purpose of this study is to examine the impacts of media symbol variety on group performance in virtual teams. Symbol variety is defined as the number of ways in which information can be communicated and includes Daft and Lengel [1986]'s multiplicity of cues and language variety. According to media richness theory and media synchronicity theory, the use of media with high symbol variety is assumed to facilitate and promote communications among virtual team members. Therefore, it is expected that the media symbol variety is positively associated with group performance in virtual teams. Furthermore, online relationship building is expected to mediate the impacts of symbol variety on the performance. To confirm the suppositions, a controlled lab experiment was conducted with 60 undergraduate students as subjects. In the experimental virtual teams, subjects were allowed to communicate with other members using text-based messenger with emoticons. Subjects in the control virtual teams were allowed to communicate using only text-based messenger. The direct impact of symbol variety on group performance in virtual teams was found insignificant. However, the online relationship was found to completely mediate the positive impact of symbol variety on group performance. The implications and limitations of this study are also discussed for future research.

• Management & Information Systems Review
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• v.13
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• pp.27-47
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• 2003

The strategic usages of IT(Information Technology) can convey important competitive advantages with an operational productivity. For this reason, many firms have heavily invested in IT and computing power. However, many companies were getting expected results by IT investment, but some companies had to be satisfied with a poor results. The question of whether or not benefit lead to expected performance is not easy to answer. The purpose of this study was to investigate the relationship among IT strategy, IT investment, and IT performance to resolve this problem. The 147 questionnaire responses completed by IS managers in manufacturing sector was conducted for a test of research hypothesis. ANOVA was used to investigate the relationship among three constructs and six factors. An operational performince of fitted group between IT strategy and IT investment was higher than not fitted group(H1). And also an competitive performance of fitted group between IT strategy and IT investment was higher than not fitted group(H2). The study shows a positive relationship between IT strategic orientation, IT investment direction, and performance of IT. The research results provide empirical evidence that supports the research hypothesis that closer fit between IT strategies and IT investment directions does lead to increase operational and competitive performance of IT.

• Journal of Communications and Networks
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• v.17 no.4
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• pp.370-383
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• 2015

Effective link quality estimation is a vital issue for reliable routing in wireless networks. This paper studies the performance of expected transmission count (ETX) under different traffic loads. Although ETX shows good performance under light load, its performance gets significantly worse when the traffic load is high. A broadcast packet storm due to new route discoveries severely affects the link ETX values under high traffic load, which makes it difficult to find a good path. This paper presents the design and implementation of a variation of ETX called high load - ETX (HETX), which reduces the impact of route request broadcast packets to link metric values under high load. We also propose a reliable routing protocol using link quality metrics, which is called link quality distance vector (LQDV). We conducted the evaluation of the performance of three metrics - HETX, ETX and minimum hop-count. The simulation results show that HETX improves the average route throughput by up to 25% over ETX under high traffic load. Minimum hop-count has poor performance compared with both HETX and ETX at all of the different traffic loads. Under light load, HETX and ETX show the same performance.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.231-239
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• 2020

The aim of this paper is to review the role of board size as part of the corporate governance system. This paper discusses one aspect of corporate governance, namely, boards, in the Indonesian context. Using the literature review method, this paper explores factors that need to be considered to determine the optimal number of boards, especially in Indonesia. We explore some determinants of board size, such as complexity and leverage, ownership structure, and financial ratio support. The results reveal that an understanding of the differences found in the two-tier board model helps us understand that the different functions of the board of commissioners and the board of directors require different test treatments from countries that adhere to one-tier systems. A review of the relationship between board size and company performance is expected to provide the corporate governance literature with insights into optimizing the sizes of boards that can improve company performance, both in terms of boards of commissioners and boards of directors. This paper proposes the simultaneous testing of board size's relationship with company performance. The results of this study are expected to make a more real contribution about the effect of board size on company performance.

• Journal of the Semiconductor & Display Technology
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• v.22 no.2
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• pp.45-49
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• 2023

When blockchain technology, which shows various applicability, is utilized as a component of a database system, the characteristics of open verification and integrity/transparency of blockchain technology can bring new functionalities or enhanced results to the existing database system. However, when applying this blockchain technology to a database system, the cost versus expected effect in various performance perspectives must be evaluated. These costs include execution time and required storage space, and the performance of the converged system may vary in analysis method depending on the configuration method of the characteristics of the blockchain. This paper aims to propose an analysis model for the entire architecture by considering aspects that are not considered in the performance analysis models of database systems and the unique characteristics of blockchains. In doing so, we are trying to build a theoretical framework as an important conceptual technique that should be considered in the evaluation process of the performance results that can be obtained through the utilization of blockchain components in database systems. What we hope is that this work is expected to provide a useful foundation for researchers interested in the convergence of database systems and blockchain technology in order to construct a system with new future functionalities.