• Journal of Korean Institute of Industrial Engineers
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• v.34 no.2
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• pp.190-204
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• 2008

Recently, it has been strongly required to establish a systematic and sustainable performance investigation and evaluation framework on governmental funding projects for IT small and medium-sized enterprises. In this paper, Data Envelopment Analysis (DEA) models are adopted for performance evaluation on governmental funding projects for IT small and medium-sized enterprises. A new data structure is proposed for the DEA performance evaluation. Generally, in using DEA models, DEA multipliers restriction is critical to achieve the reliability of DEA optimal solutions. Based on the outputs and inputs considered in this study, Acceptance Region (AR) constraints are generated and incorporated into the DEA models so as to improve the reliability of DEA efficiency scores. Associated with AR Type I (AR-I), AR Global Model (ARGM) constraints, DEA/ (AR-I, ARGM) models are designed and then sensitivity analysis follows investigating the robustness of DEA efficiency scores relating to AR constraints adjustment. Finally, a performance evaluation is illustrated regarding governmental direct funding projects from Ministry of Information and Communication (MIC) in Korea where each project unit (i.e. Decision Making Unit (DMU)) is determined whether it is efficient or not. By using DEA/(AR-I, ARGM) models designed in this paper, robustly efficient DMUs are gradually identified according to the successive AR constraints adjustment. Among 25 DMUs, results show that 6 DMUs such as B, E, G, Q, S, Y are determined as robustly efficient against AR constraints intermediate adjustment.

• Journal of Korea Port Economic Association
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• v.39 no.3
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• pp.191-210
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• 2023

The Covid-19 pandemic has had a significant impact on global logistics and supply chains, leading to major discrepancies in logistics performance across countries worldwide. Through an examination of logistics performance index and supply chain tracking data, this study aimed to identify the changes in global supply chains and logistics environments during the pandemic. The analysis of the logistics performance index showed that overall, countries around the world, especially developed nations, showed improvements in metrics such as customs and border management efficiency, the quality of trade and transport infrastructure, capability and quality of logistics services, and cargo tracking abilities. However, the competitive pricing feasibility of international transportation and the on-time delivery frequency of goods saw a decline due to the pandemic's effects. The supply chain tracking data revealed that ports in Asian countries demonstrated high processing efficiency. In contrast, the U.S. and European countries took comparatively more time. Particularly for air cargo, parcels, and express shipments, the U.S. showed relatively longer processing times, leading to logistical delays. In conclusion, during the Covid-19 pandemic, Asian countries maintained relatively high efficiency in their logistics and trade environments. Conversely, the U.S. and some European countries showed delays and decreased efficiency in various metrics. In the future, efforts should be made to address delays and congestion, namely, the deceleration of logistics processes.

• Journal of the Society of Disaster Information
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• v.19 no.4
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• pp.976-983
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• 2023

Purpose: The dynamic behavior of a bridge structure under seismic loading depends on many uncertainties, such as the nature of the seismic waves and the material and geometric properties. However, not all uncertainties have a significant impact on the dynamic behavior of a bridge structure. Since probabilistic seismic performance evaluation considering even low-impact uncertainties is computationally expensive, the uncertainties should be identified by considering their impact on the dynamic behavior of the bridge. Therefore, in this study, a global sensitivity analysis was performed to identify the main parameters affecting the dynamic behavior of bridges with I-curved girders. Method: Considering the uncertainty of the earthquake and the material and geometric uncertainty of the curved bridge, a finite element analysis was performed, and a surrogate model was developed based on the analysis results. The surrogate model was evaluated using performance metrics such as coefficient of determination, and finally, a global sensitivity analysis based on the surrogate model was performed. Result: The uncertainty factors that have the greatest influence on the stress response of the I-curved girder under seismic loading are the peak ground acceleration (PGA), the height of the bridge (h), and the yield stress of the steel (fy). The main effect sensitivity indices of PGA, h, and fy were found to be 0.7096, 0.0839, and 0.0352, respectively, and the total sensitivity indices were found to be 0.9459, 0.1297, and 0.0678, respectively. Conclusion: The stress response of the I-shaped curved girder is dominated by the uncertainty of the input motions and is strongly influenced by the interaction effect between each uncertainty factor. Therefore, additional sensitivity analysis of the uncertainty of the input motions, such as the number of input motions and the intensity measure(IM), and a global sensitivity analysis considering the structural uncertainty, such as the number and curvature of the curved girders, are required.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.2
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• pp.47-57
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• 2016

Since the Global Navigation Satellite System (GNSS) may not provide navigation information due to external interferences, many countries have plans to prepare a backup system for this situation. One of the possible GNSS backup systems is a multiple radio positioning integration system in combination with the terrestrial radio navigation system. Before constructing such a GNSS backup system, M&S software is needed to analyze if the system satisfies the performance the required navigation performance. This study presents requirements of M&S software for coverage analysis of the navigation system, and proposes an M&S software design scheme on the basis of the requirements. The M&S software is implemented, and coverage analysis is performed to verify the validity of the proposed design scheme.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.6
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• pp.550-557
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• 2001

There are several applications and error analysis methods using GPS(Global Positioning System) In most analysis positioning and timing errors are represented as the multiplication of DOP(Dilution Of Precision) and measurement errors, which are affected by the receiver and measurement type. Therefore, lots of DOPs are defined and used to analyze and predict the performance of positioning and timing systems. In this paper, the relationships between these DOPs are investigated in detail, The relationships between GDOP(Geometric DOP), PDOP(Position DOP) and TDOP(Time DOP) in the absolute positioning are de-rived. Using these relationships, the affect of clock bias is analyzed. The relationships between RGDOP(Relative DOP) and PDOP are also derived in relative positioning where the single difference and double dif-ference techniques are used. From the results, it is expected that using the common clock will give better performance when the single difference technique is used while the effects of clock is eliminate when the double difference technique is used. Finally, the error analyses of dual frequency receivers show that the narrow lane measurements give more accurate results than wide line of or L1. L2 independent measurements.

• Journal of Korea Multimedia Society
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• v.23 no.2
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• pp.317-327
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• 2020

R&D(Research and Development) efficiency analysis is a very important issue in academia and industry. Although many studies have been conducted to analyze R&D(Research and Development) efficiency since the past, studies that analyzed R&D(Research and Development) efficiency considering both patentability and patent quality efficiency according to the financial performance of a company do not seem to have been actively conducted. In this study, measuring the patent application and patent quality efficiency according to financial performance, patent quality efficiency according to patent application were applied to corporate groups related to artificial intelligence hardware technology defined as GPU(Graphics Processing Unit), FPGA(Field Programmable Gate Array), ASIC(Application Specific Integrated Circuit) and Neuromorphic. We analyze the efficiency empirically and use Data Envelopment Analysis as a measure of efficiency. This study examines which companies group has high R&D(Research and Development) efficiency about artificial intelligence hardware technology.

• Journal of Ocean Engineering and Technology
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• v.29 no.3
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• pp.255-262
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• 2015

The present study developed a numerical simulation tool for the coupled dynamic analysis of multiple turbines on a single floater (or Multiple Unit Floating Offshore Wind Turbine (MUFOWT)) in the time domain, considering the multiple-turbine aero-blade-tower dynamics and control, mooring dynamics, and platform motions. The numerical tool developed in this study was designed based on and extended from the single-turbine analysis tool FAST to make it suitable for multiple turbines. For the hydrodynamic loadings of floating platform and mooring-line dynamics, the CHARM3D program developed by the authors was incorporated. Thus, the coupled dynamic behavior of a floating base with multiple turbines and mooring lines can be simulated in the time domain. To investigate the effect of asymmetric aerodynamic loading on the global performance and mooring line tensions of the MUFOWT, one turbine failure case with a fully feathered blade pitch angle was simulated and checked. The aerodynamic interference between adjacent turbines, including the wake effect, was not considered in this study to more clearly demonstrate the influence of the asymmetric aerodynamic loading on the MUFOWT. The analysis shows that the unbalanced aerodynamic loading from one turbine in MUFOWT may induce appreciable changes in the performance of the floating platform and mooring system.

• Korea Trade Review
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• v.46 no.4
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• pp.1-16
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• 2021

This study suggests improvements in the management performance of the five largest exhibition and convention centers in Korea through financial ratio analysis. For this research, the financial ratios of each center were compared to the average of the centers as well as to the overall industry average during the past five years. According to the analysis results, the stability and growth ratios of the centers were excellent, but the profitability and activity ratios were poor. In particular, the ratios of profitability were in state of urgent need for improvement because they were at the level of severe deficits. It was analyzed that sales increase can be the key factor to improve centers' operation income and net profit to improve profitability. This study recommends measures to increase sales by using centers' facilities and their functions. The first is to actively host large-scale international meetings and conventions that only exhibition and convention centers can accommodate. The second is to attract brand exhibitions through strategic alliances with global Professional Exhibition Organizers (PEOs). Lastly, it is to organize sports and cultural events that are appropriate for incentive tours of associations and corporations.

• International Commerce and Information Review
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• v.9 no.4
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• pp.41-66
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• 2007

This paper develops a model of the export timing and export performance of venture firms by drawing by resource based view and born-global firm theory. The model aims at explaining the role of internal resources of small new venture firms and environment factors in accelerating the firm's export timing and achieving export growth. Hypothesses were developed around the following factors: management characteristics in terms of CEO's foreign experience and export commitment; organizational characteristics in terms of technological competence and marketing competence, and inter-functional cooperation; and finally environmental factors in terms of domestic and market attractiveness and foreign market attractiveness influence both the export timing and export performance. Structural equation modeling analysis by using 214 small new ventures provides a partial supports for the hypotheses. The result showed that technological competence have an influence on early export timing and that CEO's foreign experience and export commitment, technological competence and foreign market attractiveness are related export performance significantly. It also showed the significant relationship between export timing and export performance.

• Journal of Hydrogen and New Energy
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• v.27 no.4
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• pp.462-469
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• 2016

This paper presents the results of thermodynamic cycle analysis and performance tests of alternative mixtures in low temperature applications. Two near-azeotropic binary mixtures R-152a/R-1270 (35:65 by wt.%) and R-290/E170 (35:65 by wt.%) are considered in this study. They have zero ODP (Ozone Depletion Potential) and much lower GWP (Global Warming Potential) than R-404A which is an alternative of R-502. Refrigeration cycle characteristics such as cooling capacity, coefficient of performance, suction and discharge pressures and temperatures are compared to those for the baseline refrigerants (R-502 and R-404A) cycles. The performance tests are conducted at the evaporation and condensation temperatures of $5^{\circ}C$ and $45^{\circ}C$, subcooling and superheating temperatures of $5^{\circ}C$, respectively. Performance comparisons between baseline and alternative refrigerants are conducted on the same cooling capacity. The system performance of newly proposed refrigerant mixtures show promising results.