• Journal of Korea Water Resources Association
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• v.56 no.8
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• pp.509-520
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• 2023

Various drought indices are widely used for assessing drought conditions which are affected by many factors such as precipitation, soil moisture, and runoff. The values of drought indices varies depending on hydro-meteorological data and calculation formulas, and the judgment of the drought condition may also vary. This study selected four calculation components such as precipitation data length, accumulation period, probability distribution function, and parameter estimation method as the sources of uncertainty in the calculation of standardized precipitation index (SPI), and evaluated their contributions to the uncertainty using root mean square error (RMSE) and linear mixed model (LMM). The RMSE estimated the overall errors in the SPI calculation, and the LMM was used to quantify the uncertainty contribution of each factor. The results showed that as the accumulation period increased and the data period extended, the RMSEs decreased. The comparison of relative uncertainty using LMM indicated that the sample size had the greatest impact on the SPI calculation. In addition, as sample size increased, the relative uncertainty related to the sample size used for SPI calculation decreased and the relative uncertainty associated with accumulation period and parameter estimation increased. In conclusion, to reduce the uncertainty in the SPI calculation, it is essential to collect long-term data first, followed by the appropriate selection of probability distribution models and parameter estimation methods that represent well the data characteristics.

• Journal of Korean Society for Quality Management
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• v.45 no.2
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• pp.247-260
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• 2017

Purpose: The study is aimed to identify the national cultural dimensions that are affecting the quality management (QM) maturity level and the project quality performance, and analyze their relationships. Methods: This study collected the data of QM Maturity level based on Crosby's QM maturity model and the project quality performance using the Iron Triangle (Quality, Time/Schedule and Cost) from the employees who are participating in the ITER Project across the major 8 countries (China, France, Italy, Japan, Korea, Russia, U.K. and U.S.A.). Three research hypotheses are proposed concerning the national cultural dimensions in this study and Hofstede's five cultural dimensions framework are used for the statistical test. Results: The results are two folds in the study: First, there is a significant positive correlation between the QM maturity level and the project quality performance. Second, three cultural dimensions (Collectivism, Large Power Distance and Strong Uncertainty Avoidance) and five cultural dimensions (Collectivism, Large Power Distance, Strong Uncertainty Avoidance, Feminity and Long Term Orientation) have a positive impact on the QM maturity level and the project quality performance respectively. Conclusion: From the results, the understanding and consideration of the culture difference among the countries participating International Collaboration R&D project are recommended.

• Journal of the Korea Safety Management & Science
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• v.16 no.4
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• pp.305-311
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• 2014

Recently, though it was developed several services using the context-awareness technology of IoT, there exist also obstacles for high quality service. Specifically it is short the study for uncertainty of context-awareness. This study focused on understanding the effect of frequency interference among several environmental factors for location determination to increase precision of location determination. It was found that frequency interference between devices using 2.4Ghz frequency effect on the location determination precision. It was resulted that frequency interference increase the error of location determination precision. Then, we confirmed that it was required the suitable compensation method corresponding to frequency interference.

• Journal of Engineering Education Research
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• v.13 no.4
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• pp.70-76
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• 2010

This paper tries the systematic approach to risk which is a major theme in engineering ethics utilizing science and technology studies. The types of risk can be classified as technical risk, methodological risk, epistemological risk by the degree of uncertainty. The strategies for risk management can be assorted to applied science strategy, professional consultancy strategy, post-normal science strategy. These types and strategies of risk request different kinds of expertise such as technocratic expertise, interactive expertise, democratic expertise. This paper can not only contribute to complement and extend engineering ethics education but also be linked with the goals of engineering education in general.

• International Journal of Computer Science & Network Security
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• v.24 no.4
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• pp.87-106
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• 2024

Vehicle-to-Home (V2H) and Home Centralized Photovoltaic (HCPV) systems can address various energy storage issues and enhance demand response programs. Renewable energy, such as solar energy and wind turbines, address the energy gap. However, no energy management system is currently available to regulate the uncertainty of renewable energy sources, electric vehicles, and appliance consumption within a smart microgrid. Therefore, this study investigated the impact of solar photovoltaic (PV) panels, electric vehicles, and Micro-Grid (MG) storage on maximum solar radiation hours. Several Deep Learning (DL) algorithms were applied to account for the uncertainty. Moreover, a Reinforcement Learning HCPV (RL-HCPV) algorithm was created for efficient real-time energy scheduling decisions. The proposed algorithm managed the energy demand between PV solar energy generation and vehicle energy storage. RL-HCPV was modeled according to several constraints to meet household electricity demands in sunny and cloudy weather. Simulations demonstrated how the proposed RL-HCPV system could efficiently handle the demand response and how V2H can help to smooth the appliance load profile and reduce power consumption costs with sustainable power generation. The results demonstrated the advantages of utilizing RL and V2H as potential storage technology for smart buildings.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.7
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• pp.414-419
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• 2004

In TWBP new uncertainty will be increased. Risk management is risen to a important problem. Vesting contract makes market Players trade at fixed price in TWBP early stages. In the case of advanced country, market players manage risk with a future contract. When a risk management method moves from vesting contract to future contract, it may have to use together two contracts for schedule period. In this paper, risk management strategy that use vesting contract and forward contract at the same time is proposed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.2
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• pp.72-81
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• 2016

There can be included a variety of uncertainties in all measurement results whether we can perceive or not on the causes. These uncertainties may end up in lowering the reliability of measurement results and also deteriorate the level of quality. For the purpose, we tried to combine the strengths of measurement uncertainty and measurement system analysis together to present a practical flowchart so as to verify those potential variation factors in general measurement processes. As a case study, we did an experiment and gathered data on the length between two holes of an engine cylinder head which is a core part for vehicles with a coordinate measuring machine and estimated nine uncertainty factors of it. Consequently, it was identified that the four primary factors among the nine which were related to the measurement standard, random errors or spread of the repeat measurements, differences between the coefficients of thermal expansion and the environment especially had been the influence around the laboratory. Since it is impossible to analyze the equipment and appraisal variations respectively through the only measurement uncertainty, we have used the measurement system analysis following the flowchart. Showing the result of being just about 0.5% lower for the appraisal variation, and the equipment variation occupied about 7% for the total Gage R&R. Through this research, we have come to a conclusion that much more detail analysis on variation factors can be possible to be identified in measurement processes by using the developed flowchart which is composed of measurement uncertainty and measurement system analysis. Therefore, we expect engineers who are involved in quality and measurements to utilize this developed method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.983-989
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• 2007

The bird strike simulation is a problem characterized by a high degree of uncertainty. It deals with nonlinear dynamics, complicated models of bird materials and geometry, as well as a plenty of possible boundary and initial conditions. In this complex field, uncertainty management plays an important role. This paper aims to assess the effect of input uncertainty of bird strike analysis on the impact behavior of the leading edge of the WIG(Wing in Ground Effect) craft obtained with finite element analysis using LS-DYNA 3D. The uncertainties of the bird strike simulation arise due to imprecision or lack of information, due to variability or scatter, or as a consequence of model simplification. These uncertain parameters are represented by fuzzy numbers with their membership functions quantifying an initial guess for the actual value of the model parameter. Using the transformation method as a special implementation of fuzzy arithmetic, the model can be analyzed with the intention of determining the influence of each uncertain parameter on the overall bird strike behavior.

• Environmental and Resource Economics Review
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• v.28 no.2
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• pp.177-200
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• 2019

Energy demand forecast which serves as an essential input in energy policy is exposed to multiple factors of uncertainty such as GDP and weather forecast uncertainty. The Master Plan of Electricity Market in Korea which is biennially prepared is critically based on fluctuating energy demand forecast whereas its resulting proposal on electricity generation mix is substantially irreversible. The paper provides a real options model to evaluate energy transition policy by considering Knightian uncertainty as a measure to study multiple uncertainties with multiple set of probability distributions. Our finding is that the current energy transition policy under the master plan is not robust in terms of securing stable management of electricity demand and supply system.

• Journal of Digital Convergence
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• v.20 no.2
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• pp.141-154
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• 2022

This study aims to investigate how tie strength in business networks affects successful knowledge sharing, as well as the impact of environmental uncertainty on the relationship between knowledge sharing and tie strength. We gathered data through a questionnaire-based survey of 310 employees affiliated with a high-technology industry in Korea. The results highlighted the positive influence of strong ties on tacit knowledge sharing and weak ties on explicit knowledge sharing. Additionally, in this study, we determine that strong ties are strengthened to share tacit knowledge with exchange parties when environmental uncertainty is high, whereas weak ties may remain unaffected by environmental uncertainty. This study contributes to the literature on tie strength and knowledge sharing by applying social capital theory to a high-technology industry. The findings suggest that firms must take advantage of strong and weak ties to facilitate knowledge sharing to enhance competency, create novel knowledge, and obtain a competitive advantage.