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Jinwoo KIM(Jinwoo KIM),Hosung WOO(Hosung WOO) 한국4차산업학회 2023 4차산업연구 Vol.3 No.1
Purpose – By designing a PEF(Personalized Education Feedback) system for real-time prediction of learning achievement and motivation through real-time EEG analysis of learners, this system provides some modules of a personalized adaptive learning system. By applying these modules to e-learning and offline learning, they motivate learners and improve the quality of learning progress and effective learning outcomes can be achieved for immersive self-directed learning Research design, data, and methodology – EEG data were collected simultaneously as the English test was given to the experimenters, and the correlation between the correct answer result and the EEG data was learned with a machine learning algorithm and the predictive model was evaluated.. Result – In model performance evaluation, both artificial neural networks(ANNs) and support vector machines(SVMs) showed high accuracy of more than 91%. Conclusion – This research provides some modules of personalized adaptive learning systems that can more efficiently complete by designing a PEF system for real-time learning achievement prediction and learning motivation through an adaptive learning system based on real-time EEG analysis of learners. The implication of this initial research is to verify hypothetical situations for the development of an adaptive learning system through EEG analysis-based learning achievement prediction.
Kim, Jinwoo,Kim, Jin-Young,Oh, Jai-Ho,Kim, Do-Yong Korean Meteorological Society 2010 大氣 Vol.20 No.2
In this paper, an attempt has been made to build and test self-configuring weather sensor networks and internet based observation system to gather atmospheric data. The aim is to provide integrated or real-time weather information in standard form using network data access protocol. This system was successfully developed to record weather information both digital as well as visual using sensor network and web-enabled surveillance cameras. These data were transformed by network based data access protocol to access and utilize for public domain. The competed system has been successfully utilized to monitor different types of weather. The results show that this is one of the most useful weather monitoring system.
Standard Auctions with Security Bids
Jinwoo Kim 한국계량경제학회 2013 JOURNAL OF ECONOMIC THEORY AND ECONOMETRICS Vol.24 No.1
Peter DeMarzo, Ilan Kremer and Andrzej Skrzypacz (2005) study auctions where bidders compete in securities. As the main results, they show that: a steeper security generates a higher revenue for the seller; the revenue ranking between the first-price and second-price auction depends on the steepness of security; and the first-price auction combined with call option achieves the highest revenue among a general set of auction mechanisms. As pointed out by Che and Kim (2010), using steeper securities can cause the adverse selection problem and reduce the seller's revenue, in case a bidder who expects a higher return must incur a higher investment cost. While the analysis of Che and Kim (2010) focuses on the second-price auction, this paper analyzes the first-price auction to show that it is plagued by the same problem and in fact more vulnerable than the second-price auction to the adverse selection problem, which may lead to a reversal of the DKS's revenue ranking between the two auctions.
Optimization of Electropolishing on NiTi Alloy Stents and Its Influence on Corrosion Behavior
Kim, Jinwoo,Park, Jun-Kyu,Kim, Han Ki,Unnithan, Afeesh Rajan,Kim, Cheol Sang,Park, Chan Hee American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.4
<P>Nitinol or NiTi alloys are well-known as an attractive biomedical material due to their unique properties such as the shape memory effect, super-elasticity and biocompatibility. These characteristics enable them to be best candidates for implant materials such as stent. One of the major factors that strongly affect the performance of nitinol stent is its unique surface properties. In this study, the influence of electropolishing on nitinol stents and its corrosion behavior were observed. Electropolishing is an effective method for surface treatment, which not only controls the surface state but also helps to produce uniform surface layers. Therefore, to improve the surface quality of nitinol stents, we conducted an electropolishing under various conditions from 30-40 V and 10-30 s as a post heat treatment for nitinol stent manufacturing process. In order to find the optimal surface state of NiTi stents, various electropolished samples were explored using various characterization techniques. Furthermore, the potentiodynamic polarization tests were also performed to determine the corrosion resistance. The electropolished nitinol stents under the condition of 40 V for 10 s exhibited the best corrosion performance as well as surface quality.</P>
Kim, Dong Kyu,Lee, Ji Sung,Kim, Jinwoo,Kim, Mo Se,Kim, Min Soo Elsevier 2017 APPLIED ENERGY Vol.189 No.-
<P>A parametric study and performance evaluation of an organic Rankine cycle (ORC) system that uses low-grade heat at a temperature below 80 degrees C and with a cycle power of less than 10 kW was undertaken to analyze the effects of the operating conditions on the performance and efficiency. R245fa was used as the working fluid, and a scroll expander as the power generation device. A model of the system was developed and its predictions were verified by the results of experiments, which were also used to determine the appropriate charge of the working fluid for maximizing the system power output. Owing to the difference between the variations of the power generated by the expander and the power consumed by the pump, the performance of the system was found to initially increase and then decrease with increasing refrigerant charge. The parametric investigation of the ORC system was conducted by varying the pressure ratio and mass flow rate of the working fluid. Increases in both parameters were found to increase the system performance by improving the torque generation and expander speed. The variation of the system performance with the heat sink temperature, which was varied between 20 and 35 degrees C, was also examined. The system power and efficiency were observed to decrease with increasing heat sink temperature owing to the decrease in the pressure ratio resulting from the increased condensation temperature. Based on the study findings, we propose a performance map for a low-temperature low-cycle-power ORC. The power and efficiency are shown to be proportional to the heat source temperature and capacity, which varies in a manner similar to the expander performance. The findings of this study highlight the feasibility of an ORC system that uses low-grade heat at a temperature below the boiling point. (C) 2016 Elsevier Ltd. All rights reserved.</P>