• Journal of the military operations research society of Korea
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• v.34 no.1
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• pp.61-77
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• 2008

Data Envelopment Analysis(DEA) is a promising methodology to evaluate the relative efficiency of the decision-making units. We have compared the efficiency of six electric power generation companies in Korea using DEA. The analysis results by input-oriented CCR and BCC models are summarized as follows: first, different results were acquired between using input factors as total capacity of generators and as sub-totals of generator capacity based on primary energy sources. It is the result influenced by input factors which are characterized by the proportion of fixed costs(generating facilities) and variable costs(generation costs for primary energy), Second, the efficiency will be increased if the input factors selected, according to primary energy sources discussed in this research, are used during long-term expansion of electric power capacity plans. It is expected that this approach can give a feedback for management of electric power generation companies.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.6
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• pp.1331-1345
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• 2017

Binary instrumentation has been developed for monitoring and debugging executables without their source codes. Previous efforts on the binary instrumentation are mainly focused on its capability and accuracy, but not on efficiency for practical application. In particular, criteria and measurement methodologies for evaluating and comparing the efficiency of binary investigation tools and algorithms do not estimated yet. In this paper, we propose the instrumentation primitives which are a unit functionality and measurement methodology. Through the empirical experiments by adopting the proposed methodology on DynamoRIO and Pin, we show the feasibility of the proposal.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.7_8
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• pp.341-351
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• 2003

For debugging effectively the shared-memory programs with nested parallelism, it is important to detect efficiently the first races which incur non-deterministic executions of the programs. Previous on-the-fly technique detects the first races in two passes, and shows inefficiencies both in execution time and memory space because the size of an access history for each shared variable depends on the maximum parallelism of program. This paper proposes a new on-the-fly technique to detect the first races in two passes, which is constant in both the number of event comparisons and the space complexity on each access to shared variable because the size of an access history for each shared variable is a small constant. This technique therefore makes on-the-fly race detection more efficient and practical for debugging shared-memory programs with nested parallelism.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2406-2419
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• 2010

This study aims to elevate the usefulness of the current annual Accreditation of Hospitals. To achieve this purpose, A modeling of an efficiency analysis based on DEA and AHP to the Accreditation of Hospitals Data from 2004 to 2008. By applying to AHP and DEA_AR to the scores derived from the various domains in data, An adequate prediction model about conversion factor in fee contract is made. By summarizing information derived from DEA, factor analysis and Generalized Linear Model, The linear functions combining conversion factor and efficiency index is successfully established. The factor analysis with AHP was used to merge diverse scores from the domains of evaluation. Not only the input and output initially introduced, AHP scores, dummy variables of hospital classification, geographical location are effective variables to forecast a conversion factor. If a predicted conversion factors from efficiency is used, It will be a great contributions to the annul doctor's fee contract.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.9
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• pp.1003-1008
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• 2012

The paper presents an Experimental Vehicle Model (EVM), that utilizes the kinematic characteristics of suspensions from SPMD test data. The relative displacement and orientation of a wheel with respect to the body are represented as a function of the vertical displacement of the wheel. The equations of motion of the vehicle are formulated in terms of local coordinates that do not require coordinate transformation, which improves the efficiency of dynamic analysis. The EOM was modularized for each suspension model, and a $6{\times}6$ vehicle model was obtained by combining six suspensions. The analysis results were compared with ADAMS to verify the accuracy of the EVM. This study also verifies the feasibility of real-time simulation with the developed EVM. For a vehicle simulation for 1 ms, the real simulation time required within 20% of the prescribed time. This result shows that the EVM meets the real-time simulation requirements.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.4
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• pp.119-131
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• 2018

The increase of high-resolution spatial data and methodological developments in recent years has enabled a detailed analysis of individual experiences in space and over time. However, despite the increasing availability of data and technological advances, such individual-level analysis is not always possible in practice because of its computing requirements. To overcome this limitation, there has been a considerable amount of research on the use of high-performance, public cloud computing platforms for spatial analysis and simulation. The purpose of this paper is to empirically evaluate the efficiency and effectiveness of spatial analysis in cloud computing platforms. We compare the computing speed for calculating the measure of spatial autocorrelation and performing geographically weighted regression analysis between a local machine and spot instances on clouds. The results indicate that there could be significant improvements in terms of computing time when the analysis is performed parallel on clouds.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.128-130
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• 2016

The digital content industry is growing rapidly with the popularity of online content and mobile devices. This study estimates the technical efficiency of the online digital content industry, and identifies factors that could be causing inefficiency. Unlike most previous studies, which adopted input-oriented or output-oriented DEA model, this study employs non-oriented DEA model in order to deal with both input surpluses and output shortfalls. The input variables for the empirical analysis are number of companies and number of workers. The total sales is used as the output variables. The empirical results show that the technical efficiency of the online digital content industry is relatively low mainly due to the scale efficiency rather than the pure technical efficiency. This implies that industry-specific policies should be implemented in order to improve technical efficiency as well as to strengthen technological innovation capability. Therefore, it is expected that the results obtained in this study can be used as a good reference for helping the online digital content industry enhance their competitiveness.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.3
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• pp.31-42
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• 2005

We consider a network storage model whose administrator can not be fully trusted. In this model, we assume that all data stored are encrypted for data confidentiality and one owner distributes the decryption key for each time period to users. In this paper, we propose three privilege management schemes. In the first scheme, called Temporal Privilege Management (TPM), we use a symmetric encryption based on one-way function chains for key encapsulation. In the second scheme, called Asymmetric Temporal Privilege Management (ATPM), anyone can encrypt the data using the public key of owner, but only privileged users can decrypt the encrypted data. Finally, we present a scheme to restrict writers' privilege using ID-based signatures in ATPM. In our schemes, the privilege managements are based on the time and the addition of users is efficient. Specially, applying TPM and ATPM, we can solve the back-issue problem.

• Journal of the Korea Society of Computer and Information
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• v.29 no.1
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• pp.97-109
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• 2024

This research aims to investigate how major cities in Korea utilize smart city-related technologies, develop key performance indicators (KPIs) to measure the smartness and efficiency of cities, and propose a methodology for assessing and suggesting smart city policy directions based on Data Envelopment Analysis (DEA). Referring to the CITYkeys Smart City Performance Measurement Framework, 10 key performance indicators (KPIs) were derived. For each KPI, city statistical data were allocated to input and output variables, and 15 cities were assigned as Decision Making Units (DMUs). The DEA methodology was employed to evaluate the operational efficiency and scale profitability of cities, providing insights into the operational efficiency of each city. Finally, the operational efficiency among DMUs was ranked to propose smart city policy directions for each city.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.107-117
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• 2016

This study examines information efficiency of financial information on the firm value for the listed manufacturing companies in Korea stock market in terms of timing pattern of information. We set 3 different test periods based on the financial statement released years - the current year, 90 days before financial statement announcement and the next year. We introduce using the stepwise regression method to examine the effect of financial variables on the stock returns. The financial variables include profitability ratio, growth ratio, stability ratio, activity ratio and market valuation ratio. The results of the study showed that both growth and profitability ratio affected the current year stock returns, while stability and activity ratio affected the next year stock returns. Growth rate of total asset affects both current year and next year stock returns. Our findings imply that the period in which financial information is reflected in the firm value, could vary with the characteristics of financial information.