• Journal of the Korea Society for Simulation
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• v.25 no.4
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• pp.137-144
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• 2016

This paper proposes characteristics of management system for defense system development. This research shows how effectiveness of SBA (simulation-based acquisition) can be represented even necessity of SBA is recognized by researchers. To achieve this goal there are two key information, (1)the cost for modeling and simulation and (2) number of trial and error of a certain step in a phase. This paper presents user interface of gathering those two key information and a way of showing the effectiveness of SBA using those two information. In this work, all the data gathering for calculation of effectiveness should be considered as a saving logs. The contribution of this research is in presenting quantitative value representing effectiveness of SBA and proposing a system architecture for deriving the quantitative effectiveness.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.9
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• pp.729-738
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• 2021

Feedback flow control using an artificial neural network was numerically investigated for NACA0015 Airfoil to suppress flow separation on an airfoil. In order to achieve goal of flow control which is aimed to reduce the size of separation on the airfoil, Blowing&Suction actuator was implemented near the separation point. In the system modeling step, the proper orthogonal decomposition was applied to the pressure field. Then, some POD modes that are necessary for flow control are extracted to analyze the unsteady characteristics. NARX neural network based on decomposed modes are trained to represent the flow dynamics and finally operated in the feedback control loop. Predicted control signal was numerically applied on CFD simulation so that control effect was analyzed through comparing the characteristic of aerodynamic force and spatial modes depending on the presence of the control. The feedback control showed effectiveness in pressure drag reduction up to 29%. Numerical results confirm that the effect is due to dramatic pressure recovery around the trailing edge of the airfoil.

• Journal of Family Relations
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• v.22 no.1
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• pp.23-40
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• 2017

Objectives: The major purpose of the study is to examine structural relation among teenager's perception of parenting attitudes, peer attachment, resilience and meaning in life. In order to achieve purpose of the study, we will develop reliable criterion which can measure variable. Method: We will set up structural relational model from relationship between internal and external variables that can influence teenager's meaning in life and we will examine the relationship between variables through structural equation analysis. we will find structural relationship among parenting attitudes, peer attachment, resilience and meaning in life. Results: We analyzed structural relationship among variables targeting 744 middle school and high school students. Teenager's perception of parenting attitudes have positive influence on peer attachment. This shows that teenager perception of fostering attitude have a positive influence even though teenager percepts parent's foster attitude as overprotective or compassionate. However, if teenager percept fostering attitude as overprotective, teenager perception of parenting attitudes doesn't have influence on resilience. Parent's compassionate attitude not only directly influence resilience but also influence resilience through peer attachment. This validates that individual psychological factor, such as how teenager accept and interpret surrounding environment can influence resilience. Peer attachment relationship not only directly influence resilience but also influence meaning of life through resilience. The resilience has direct effect on meaning in life. Conclusions: When one of education goal is to help teenager to find meaning in life and to reach self-realization, We need to have interest in resilience which is known factor for contributing meaning in life. As previous teenager studies has approached this problem, such as maladjustment, delinquency, and depression, it is significant that this study is examined in positive a psychological perspective which focus on healthy adjustment, such as meaning in life based on teenager's resilience and happiness.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.1
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• pp.107-110
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• 2021

The goal of this study was to investigate moisture sorption characteristics of Lactobacillus brevis-fermented sea tangle Saccharina japonica, Mekabu fucoidan, and these mixture powders. Moisture sorption isotherms of powders were determined at 37℃ using the static gravimetric technique in a water activity (aw) range of 0.11-0.93. Equilibrium moisture content (Xeq) values of the fermented sea tangle powder were almost 3 times when aw<0.7 and increased upto almost 4 times when aw<0.9 higher than mekabu fucoidan powder. In these reason, to improve strong hygroscopic nature of the fermented sea tangle powder, fermented sea tangle and mekabu fucoidan powders were dissolved as ratios of 7:3, 5:5, and 3:7 (w/w) in a distilled water and then freeze dried. Xeq values of mixture powders were around average value of sum of both powders at all aw ranges. All moisture sorption isotherms of powders exhibited typical J-shaped type III. Xeq of mixture powders increased with increasing aw and decreased as increasing proportion of mekabu fucoidan powder. The Peleg model was found to accurately describe moisture sorption isotherms of powders. The results can be used to understand hygroscopic nature of powders, improve shelf life, and retain quality across postharvest processing.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.180-196
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• 2021

The goal of this research is to examine the effects of sports star influencer advertising value on brand equity in social networking sites. In particular, this study identifies the moderating role of consumer team identification. A total of 350 university students participated via online survey. To test proposed hypotheses, confirmatory factor analysis, structural equation modeling, and multi-group analysis were employed. It was found that informativeness, entertainment, and credibility showed significant positive effects on brand equity. Also, significant moderation effects of team identification were found in that consumers with high team identification compared to those with low team identification perceived higher value of entertainment. On the other hand, consumers with low team identification perceived more irritation than those with high team identification. This study contributes to the understanding of sports star influencer advertising in social networking sites. Theoretical and practical implications as well as suggestions for future research in this area are provided.

• The Korean Journal of Applied Statistics
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• v.34 no.2
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• pp.153-166
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• 2021

A main goal of pharmacogenomics studies is to predict individual's drug responsiveness based on high dimensional genetic variables. Due to a large number of variables, feature selection is required in order to reduce the number of variables. The selected features are used to construct a predictive model using machine learning algorithms. In the present study, we applied several hybrid feature selection methods such as combinations of logistic regression, ReliefF, TurF, random forest, and LASSO to a next generation sequencing data set of 400 epilepsy patients. We then applied the selected features to machine learning methods including random forest, gradient boosting, and support vector machine as well as a stacking ensemble method. Our results showed that the stacking model with a hybrid feature selection of random forest and ReliefF performs better than with other combinations of approaches. Based on a 5-fold cross validation partition, the mean test accuracy value of the best model was 0.727 and the mean test AUC value of the best model was 0.761. It also appeared that the stacking models outperform than single machine learning predictive models when using the same selected features.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.2
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• pp.27-37
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• 2020

The Fukushima Daiichi accident in 2011 revealed some vulnerabilities of existing Nuclear Power Plants (NPPs) under extended Station Blackout (SBO) accident conditions. One of the key Severe Accident Management (SAM) strategies developed post Fukushima accident is the In-Vessel Retention (IVR) Strategy which aims to retain the structural integrity of the Reactor Pressure Vessel (RPV). RELAP/SCDAPSIM/MOD3.4 is selected to predict the thermal-hydraulic response of APR1400 undergoing an extended SBO. To assess the effectiveness of the IVR strategy, it is essential to quantify the underlying uncertainties. In this work, both the epistemic and aleatory uncertainties are considered to identify the success window of the IVR strategy. A set of in-vessel relevant phenomena were identified based on Phenomena Identification and Ranking Tables (PIRT) developed for severe accidents and propagated through the thermal-hydraulic model using Wilk's sampling method. For this work, a Systems Engineering (SE) approach is applied to facilitate the development process of assessing the reliability and robustness of the APR1400 IVR strategy. Specifically, the Kossiakoff SE method is used to identify the requirements, functions and physical architecture, and to develop a design verification and validation plan. Using the SE approach provides a systematic tool to successfully achieve the research goal by linking each requirement to a verification or validation test with predefined success criteria at each stage of the model development. The developed model identified the conditions necessary for successful implementation of the IVR strategy which maintains the vessel integrity and prevents a melt-through.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.139-146
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• 2022

Recently, solving industrial and social problems and creating new values based on big data and AI is being discussed as the main policy goal. The new government also set the digital platform government as a national task in order to achieve new value creation based on big data and AI. However, studies that summarize and diagnose discussions over the past five years are insufficient. Therefore, this study diagnoses the discussions over the past 5 years using the 4th industrial revolution as a keyword. After collecting news editorials from 2017 to 2022 by applying the text mining technique, 9 major topics were discovered. In conclusion, this study provided implications for the government's task to prepare for the future society.

• Journal of Internet Computing and Services
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• v.23 no.1
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• pp.95-103
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• 2022

The goal of education and training in military is to foster strong combatants who can fight and defeat enemies. The Korean military is deeply aware of the importance of education & training, and has been introducing various advanced training systems so far. Despite these efforts, however, the military environment to maintain and strengthen the level of training is becoming increasingly difficult. In this study, it was conducted on the effectiveness analysis and utilization of the game system for military education & training through literature review. As a result of literature analysis, the introduction of the game system could be expected to have various effects throughout the cognitive and behavioral areas. Based on this effect analysis, the concept and shape of game system operation for each purpose were derived, and an improved plan using the game system was proposed.

• Steel and Composite Structures
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• v.43 no.2
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• pp.165-183
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• 2022

Most transportation departments have recognized and developed procedures to address the ever-increasing weights of trucks traveling on bridges in a service today. Transportation agencies also recognize the issues with overheight vehicles' collisions with bridges, but few stakeholders have definitive countermeasures. Bridges are becoming more vulnerable to collisions from overheight vehicles. The exact response under lateral impact force is difficult to predict. In this paper, nonlinear impact analysis shows that the degree of deformation recorded through the modeling of the unprotected vehicle-girder model provides realistic results compared to the observation from the US-61 bridge overheight vehicle impact. The predicted displacements are 0.229 m, 0.161 m, and 0.271 m in the girder bottom flange (lateral), bottom flange (vertical), and web (lateral) deformations, respectively, due to a truck traveling at 112.65 km/h. With such large deformations, the integrity of an impacted bridge becomes jeopardized, which in most cases requires closing the bridge for safety reasons and a need for rehabilitation. We proposed different sacrificial cushion systems to dissipate the energy of an overheight vehicle impact. The goal was to design and tune a suitable energy absorbing system that can protect the bridge and possibly reduce stresses in the overheight vehicle, minimizing the consequences of an impact. A material representing a Sorbothane high impact rubber was chosen and modeled in ANSYS. Out of three sacrificial schemes, a sandwich system is the best in protecting both the bridge and the overheight vehicle. The mitigation system reduced the lateral deflection in the bottom flange by 89%. The system decreased the stresses in the bridge girder and the top portion of the vehicle by 82% and 25%, respectively. The results reveal the capability of the proposed sacrificial system as an effective mitigation system.