• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.1
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• pp.9-20
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• 2019

Korea's R&D investment has significantly increased in recent years. However, the efficiency of R&D investment is still in question. In order to examine the ways to improve the efficiency of R&D investment, this paper presents dynamic analysis on both quantitative and qualitative efficiency of R&D projects. A Data Envelopment Analysis(DEA)/Window method is used to analyze static and dynamic efficiencies of Industrial Material R&D projects in Korea from 2012 to 2016. As a result, statistically significant differences between quantitative and qualitative efficiency have been found. It has been observed that characteristics of Decision Making Units(DMUs) have an impact on both static and dynamic efficiencies. In particular, textile and ceramic projects showed relatively stable qualitative efficiency for a short-term perspective, while steel and chemical projects showed such stability for a long-term perspective. Among the types of project principals, universities showed relatively stable efficiency, compared with private sectors and research institutes. The results of this paper can be used as a guideline to manage the performance and stability of R&D projects' efficiency.

• Journal of KSNVE
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• v.8 no.1
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• pp.139-145
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• 1998

A great deal of effort has been invested in upgrading the performance and the efficiency of dynamic analysis of mechanical structures. Using experimental modal analysis(EMA) or finite element analysis(FEA) data of mechanical structures, the performance and efficiency can be effectively evaluated. In order to analyze complex structures such as automobiles and aircrafts, for the sake of computing efficiency, the dynamic substructuring techniques that allow to predict the dynamic behavior of a structure are widely used. Through linking a modal model obtained from EMA and an analytical model obtained from FEA, the best conditioned strucutres can be proposed. In this study, a new algorithm of substructre synthesis method, Multi-FRF synthesis method, is proposed to analyze a structure composed of many substructures.

• The Journal of Society for e-Business Studies
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• v.26 no.2
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• pp.45-59
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• 2021

As software(SW) has been considered as a key driver of the fourth industrial revolution, significant R&D investment has been made by Korean government. Despite the attention and support by the government, systematic analysis on the SW R&D efficiency has not been fully addressed. In this study, the efficiency of SW national research and development projects was analyzed using Data Envelopment Analysis(DEA) techniques. Efficiency was measured from both static and dynamic perspectives based on 1,463 projects conducted by the National IT Industry Promotion Agency(NIPA) from 2008 to 2018. The static efficiency analysis identified the causes of inefficiency as scale and technology problems. As a result of dynamic efficiency analysis, we present a sector-specific response model using an efficiency-stability matrix. This study is meaningful in that efficiency analysis was conducted on the entire SW national R&D project, and static/dynamic efficiency analysis results are expected to be used as a guideline for planning SW national R&D project.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.12
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• pp.3782-3791
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• 1996

A great deal of effert has been invested in upgrading the performance and the efficiency of mechanical structures. Using experimental modal analysis(EMA) or finite element analysis(FEA) data of mechanical structures, this performance and efficiency can be effectively evaluated. In order to analyze complex structures such as automobiles and aircraft, for the sake of computing efficiency, the dynamic substructuring techniques that allow to predict the dynamic behavior of a structure based on that of the composing structures, are widely used. By llinking a modal model obtained from EMA and an analytical model obtained from FEA, the best conditioned structures can be desinged. In this paper, a new algorithm for structural dynamic modification-SRFSM (substructure response function sensitivity method) is proposed by linking frequency responce function synthesis and response function sensitivity. A mehtod to obtain response function sensitivity using direct derivative of mechanical impedance, is also used.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1109-1114
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• 2022

The SMART (System-integrated Modular Advanced ReacTor) is an integral-type small modular reactor developed by KAERI (Korea Atomic Energy Research Institute). This paper discusses the feasibility and applicability of a 3D-based equivalent model using dynamic condensation method for seismic analysis of a SMART control rod drive mechanism. The equivalent model is utilized for complicated seismic analysis during the design of the SMART. While the 1D-based beam-mass equivalent model is widely used in the nuclear industry for its calculation efficiency, the 3D-based equivalent model is suggested for the seismic analysis of SMART to enhance the analysis accuracy of the 1D-based equivalent model while maintaining its analysis efficiency. To verify the suggested model, acceleration response spectra from seismic analysis based on the 3D-based equivalent model are compared to those from the 1D-based beam-mass equivalent model and experiments. The accuracy and efficiency of the dynamic condensation method are investigated by comparison to analysis results based on the conventional modeling methodology used for seismic analysis.

• Journal of the Korea Society of Computer and Information
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• v.22 no.11
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• pp.1-7
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• 2017

In this paper, we introduce three monitoring filtering techniques which reduce the overheads of dynamic data race detection. It is well known that detecting data races dynamically in multi-threaded programs is quite hard and troublesome task, because the dynamic detection techniques need to monitor all execution of a multi-threaded program and to analyse every conflicting memory and thread operations in the program. Thus, the main drawback of the dynamic analysis for detecting data races is the heavy additional time and space overheads for running the program. For the practicality, we also empirically compare the efficiency of three monitoring filtering techniques. The results using OpenMP benchmarks show that the filtering techniques are practical for dynamic data race detection, since they reduce the average runtime overhead to under 10% of that of the pure detection.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.6
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• pp.557-563
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• 2016

The energy absorption efficiency of a wave power generation system is calculated as the ratio of the wave power to the power of the system. Because absorption efficiency depends on the dynamic behavior of the wave power generation system, a dynamic analysis of the wave power generation system is required to estimate the energy absorption efficiency of the system. In this study, a dynamic analysis of the wave power generation system under wave loads is performed to estimate the energy absorption efficiency. RecurDyn is employed to carry out the dynamic analysis of the system, and the Morison equation is used for the wave load model. According to the results, the lower the wave height and the shorter the period, the higher is the absorption efficiency of the system.

• KIEAE Journal
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• v.15 no.2
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• pp.95-101
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• 2015

Purpose: A photovoltaic/thermal system is a solar collector combining photovoltaic module with a solar thermal collector, which produces electricity and heat at the same time. PVT system removes heat from PV module through air or liquid that would help to raise the efficiency of the PV systems performance. Many innovative systems and products have been put forward and their quality evaluated by academics and professionals. However, even though various of PVT system were developed and several systems were applied to practical use, there have been few researches for the performance analysis using the dynamic simulation. Method: In this study, the review of recent research and development trend for PVT systems were conducted. Furthermore, in order to develop the optimum design method, the performance analysis for PVT system was conducted by a dynamic simulation. Result: In the results, it was found that the performance of PVT system significantly depends on the ambient temperature and solar radiation. Moreover, in the weather condition of Seoul, average efficiency of electricity and heat in heating season were 13.79 and 41.85%, and they in cooling season were 14.39% and 26.18%, respectively.

• Journal of the Korean Society of Safety
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• v.35 no.5
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• pp.39-48
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• 2020

This study proposes a fast estimation method of dynamic reliability indices or failure probability for SDOF structure subjected to earthquake excitations. The proposed estimation method attempts to derive coefficient function for correcting dynamic effects from static reliability analysis in order to estimate the dynamic reliability analysis results. For this purpose, a total of 60 cases of structures with various characteristics of natural frequency and damping ratio under various allowable limits were taken into account, and various types of approximation coefficient functions were considered as potential candidate models for dynamic effect correction. Each reliability index was computed by directly performing static and dynamic reliability analyses for the given 60 cases, and nonlinear curve fittings for potential candidate models were performed from the computed reliability index data. Then, the optimal estimation model was determined by evaluating the accuracy of the dynamic reliability analysis results estimated from each candidate model. Additional static and dynamic reliability analyses were performed for new models with different characteristics of natural frequency, damping ratio and allowable limit. From these results, the accuracy and numerical efficiency of the optimal estimation model were compared with the dynamic reliability analysis results. As a result, it was confirmed that the proposed model can be a very efficient tool of the dynamic reliability estimation for seismically excited SDOF structure since it can provide very fast and accurate reliability analysis results.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.353-356
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• 2005

We developed a dynamic model of PEM fuel cell system which can analyze its transient response to dynamic load current. System components such as compressor, air cooler, humidifier, and stack were modeled based on their dynamic equations and performance maps by using Matlab Simulink platform. Through this simulation model, dynamic characteristics of fuel cell system including oxygen excess rat io, stack voltage, and system efficiency were shown. In addition to that, we briefly analyzed the humidity effect on cathode pressure and system efficiency, expecting that this model can be further used to optimize fuel cell system parameters just like operating pressure and temperature, humidity and oxygen excess ratio.