• 시스템엔지니어링학술지
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• 제16권2호
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• pp.67-77
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• 2020

Traditionally nuclear thermal hydraulic and nuclear safety has relied on numerical simulations to predict the system response of a nuclear power plant either under normal operation or accident condition. However, this approach may sometimes be rather time consuming particularly for design and optimization problems. To expedite the decision-making process data-driven models can be used to deduce the statistical relationships between inputs and outputs rather than solving physics-based models. Compared to the traditional approach, data driven models can provide a fast and cost-effective framework to predict the behavior of highly complex and non-linear systems where otherwise great computational efforts would be required. The objective of this work is to develop an AI algorithm to predict the peak fuel cladding temperature as a metric for the successful implementation of FLEX strategies under extended station black out. To achieve this, the model requires to be conditioned using pre-existing database created using the thermal-hydraulic analysis code, MARS-KS. In the development stage, the model hyper-parameters are tuned and optimized using the talos tool.

• 한국치위생학회지
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• 제21권4호
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• pp.393-402
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• 2021

Objectives: As the school-age population continues to decline in Korea, the consolidation and abolition of departments continues with the economic logic. This study aimed to analyze the relative competitiveness of the department of dental hygiene and to investigate the effectiveness of the YouTube platform being used to promote admission. Methods: Using the admission result data provided by the Korea council for university education, the new student competition rate and recruitment rate of the department of dental hygiene were compared with those of the departments of natural sciences and all other departments. Also, the effect of YouTube channel operation on them was analyzed. Results: The department of dental hygiene showed a slight advantage but it was not particularly the case compared to other departments of natural sciences. The promotion using YouTube did not have any significant effects. Conclusions: Considering that the school-age population will rapidly decrease in the future, more active strategies are needed.

• International Journal of Internet, Broadcasting and Communication
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• 제13권3호
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• pp.137-147
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• 2021

We aimsto examine the determinants of visitors' positive word-of-mouth (WOM) in a web-based virtual reality contemporary art exhibition. We also examines the effects of 3 realms of experience (entertainment, esthetic, escapist) on emotional arousal, how this emotional arousal affects memory and positive word-of-mouth, how memory affects positive word-of-mouth and how age moderate all of the paths. We examined a total of 297 visitors and was conducted through an online survey focusing on Chinese users of ages 20-49. The analysis results showed that entertainment and esthetic have an effect on emotional arousal, but escapist did not. The results also showed emotional arousal has an effect on memory and positive WOM. Memory did not affect positive word-of-mouth. Finally, age has a moderate effect on all the paths, except for the path form escape towards emotional arousal and memory to positive word-of-mouth. The theoretical implications of this study are meaningful exhibition research. While, it also will be helpful to segment the web-based virtual reality art exhibition visitors by dividing into 3 groups (20s, 30s, 40s) and to provide marketing and operation strategies.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2883-2897
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• 2022

According to the Renewable Energy 3020 Implementation Plan announced in 2017 by the South Korean government, the electricity share of renewable energy will be expanded to 20% of the total electricity generation by 2030. Given the intermittency of electricity generation from renewable energy, realization of such a plan presents challenges to managing South Korea's isolated national electric grid and implies potentially large excess electricity generation in certain situations. The purpose of this study is: 1) to develop a model to accurately simulate the effects of excess electricity generation from renewables which would arise during the transition, and 2) to propose strategies to manage excess electricity generation through effective utilization of domestic electricity generating capabilities. Our results show that in periods of greater PV and wind power, namely the spring and fall seasons, the frequency of excess electricity generation increases, while electricity demand decreases. This being the case, flexible operation of coal and nuclear power plants along with LNG and pumped-storage hydroelectricity can be used to counterbalance the excess electricity generation from renewables. In addition, nuclear energy plays an important role in reducing CO₂ emissions and electricity costs unlike the fossil fuel-based generation sources outlined in the 8th Basic Plan.

• 전력전자학회논문지
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• 제27권5호
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• pp.425-430
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• 2022

A pumped storage power station is an important means to solve the problem of peak load regulation and ensures the safety of power grid operation. The doubly fed variable-speed pumped storage (DFVSPS) system adopts a doubly fed induction machine (DFIM) to replace the synchronous machine used in traditional pumped storage. The stator of DFIM is connected to the power grid, and the three-phase excitation windings are symmetrically distributed on the rotor. Excitation current is supplied by the converter. The active and reactive power of the unit can be quickly adjusted by adjusting the amplitude, frequency, and phase of the rotor-side voltage or current through the converter. Compared with a conventional pumped storage hydropower station (C-PSH), DFVSPS power stations have various operating modes and frequent start-up and shutdown. This study introduces the structure and principle of the DFVSPS unit. Mathematical models of the unit, including a model of DFIM, a model of the pump-turbine, and a model of the converter and its control, are established. Fast power control strategies are proposed for the unit model. A 300 MW model of the DFVSPS unit is established in MATLAB/Simulink, and the response characteristics in generating mode are examined.

• Smart Structures and Systems
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• 제29권1호
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• pp.207-220
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• 2022

Structural health monitoring (SHM) plays a vital role in the maintenance and operation of constructions. In recent years, autonomous inspection has received considerable attention because conventional monitoring methods are inefficient and expensive to some extent. To develop autonomous inspection, a potential approach of crack identification is needed to locate defects. Therefore, this study exploits two deep learning-based segmentation models, DeepLabv3+ and Mask R-CNN, for crack segmentation because these two segmentation models can outperform other similar models on public datasets. Additionally, impacts of label quality on model performance are explored to obtain an empirical guideline on the preparation of image datasets. The influence of image cropping and label refining are also investigated, and different strategies are applied to the dataset, resulting in six alternated datasets. By conducting experiments with these datasets, the highest mean Intersection-over-Union (mIoU), 75%, is achieved by Mask R-CNN. The rise in the percentage of annotations by image cropping improves model performance while the label refining has opposite effects on the two models. As the label refining results in fewer error annotations of cracks, this modification enhances the performance of DeepLabv3+. Instead, the performance of Mask R-CNN decreases because fragmented annotations may mistake an instance as multiple instances. To sum up, both DeepLabv3+ and Mask R-CNN are capable of crack identification, and an empirical guideline on the data preparation is presented to strengthen identification successfulness via image cropping and label refining.

• 공학교육연구
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• 제25권5호
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• pp.75-84
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• 2022

In the post-Corona era, blended learning will be one of the most important instructional strategies for successful education. The purpose of this study is to examine reliability and validity of the instrument developed in the instructional aspect so that a successful blended learning can take place. This instrument consists of 31 items to evaluate class operation, online learning environment, online contents, offline class, interaction and overall satisfaction. For this study, a survey was conducted in LMS and the responses of 164 students were used for analysis. Confirmatory factor analysis was used to evaluate validation of this instrument and this analysis was run in R studio. As a result of CFA, the standardized factor loadings of all items were 0.930~0.754 and the reliability and validity of all constructs were adequate. The results of this instrument enable universities to manage the quality of their classes and instructors can use them as self-checklist to improve future classes in terms of instructional points. Finally, this instrument can be used in a variety of learner-centered learning environments.

• 디지털정책학회지
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• 제2권1호
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• pp.1-7
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• 2023

본 중국에서는 시중은행들이 모바일뱅킹을 출시하고 있으며, 동질화된 상품으로 모바일뱅킹 경쟁이 치열하다.모바일뱅킹 월간 활성고객(MAU)은 모바일뱅킹 운영 성과를 평가하는 중요한 지표로 시중은행들이 직면한 과제이다.본 연구의 목적은 자동판매기를 이용하여 모바일뱅킹의 월간 고객활성화를 위한 전략을 모색하는 것이다. 본 연구는 문헌법과 사례법을 통해 연구를 수행하였으며, 연구 결과에 따르면 자동판매기를 사용하면 모바일뱅킹의 월간 활성고객을 효과적으로 향상시킬 수 있을 뿐만 아니라 차별화된 전략을 실현하여 모바일뱅킹 시장을 점유할 수 있다.동시에 이 연구는 상업 은행의 비즈니스 발전에 일정한 도움과 지도 의의가 있다.

• Journal of Trauma and Injury
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• 제35권4호
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• pp.261-267
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• 2022

Purpose: With the increasing number of polytrauma patients treated at high-level trauma centers, plastic surgery has entered the specialty of traumatology. Plastic surgeons specialize in the simultaneous surgical care of patients with facial or hand trauma and soft tissue injuries requiring microsurgery. The purpose of this study was to introduce the role of plastic surgery in a high-level trauma center. Methods: Between January 2020 and December 2020, 5,712 patients with traumatic injuries were admitted to the emergency department of a tertiary hospital. Of these 5,712 patients, 1,578 patients were hospitalized for surgical treatment and/or critical care. Among the 1,578 hospitalized trauma patients, 551 patients (35%) required at least one plastic surgery procedure. The patient variables included age, sex, etiology, the injured area, and injury characteristics. We also retrospectively investigated surgical data such as the duration of the operation, hospital stay, length of time from injury to surgery, and collaboration with other departments. Results: The most common injury referred to plastic surgery was facial trauma (41%), followed by hand trauma (36%), and soft tissue injuries requiring microsurgery in various parts of the body other than the hand (7%). The majority of facial and hand traumas were concomitant injuries. Sixteen percent of patients underwent collaborative surgical management for polytrauma involving both plastic surgery and another department. Conclusions: The role of plastic surgery in multidisciplinary teams at high-level trauma centers has become increasingly important. The results of this study may help in the development of multidisciplinary trauma team strategies and future workforce planning.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.800-807
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• 2009

The limited public funds available for infrastructure projects have led governments to consider private entities' participation in long-term contracts for finance, construction, and operation of these projects to share risks and rewards between the public and the private. Because these projects have complicated risk evolutions, diverse contractual forms for each project member to hedge risks involved in a project are necessary. In light of this, Build-Operate-Transfer(BOT) model is considered as effective to accomplish Public Private Partnerships(PPPs) with a characteristic of an ownership-reversion. In BOT projects, the government has used such an incentive system as minimum revenue guarantee(MRG) agreement to attract the private's participation. Although this agreement turns out critical in success of BOT project, there still exist problematic issues in a financial feasibility analysis since the traditional capital budgeting theory, Net Present Value(NPV) analysis, has failed to evaluate the contingent characteristic of MRG agreement. The purpose of this research is to develop real option model based on option pricing theory so as to provide a theoretical framework in valuing MRG agreement in BOT projects. To understand the applicability of the model, the model is applied to the example of the BOT toll road project and the results are compared with that by NPV analysis. Finally, we found that the impact of the MRG agreement is significant on the project value. Hence, the real option model can help the government establish better BOT policies and the developer make appropriate bidding strategies.