• Journal of Power Electronics
• /
• v.18 no.6
• /
• pp.1771-1779
• /
• 2018

Modern trams with a super capacitor have gained a lot of attention in recent years due to its reliability, convenience, energy conservation and environmental friendliness. Because of its special charging characteristic, the traditional charging structure and control strategy cannot satisfy its charging requirements. This paper presents a new charging topology for fast charging modern trams with a super capacitor and it designs a controller using continuous control set model predictive control (CCS-MPC). There are three contributions in this paper. First, a new charging structure is designed and its mathematics model is derived. The cascade structure is adopted instead of the parallel structure to simplify the control process and to keep the rated power of the controllable part low. Second, a MPC control strategy is proposed to satisfy the charging characteristic. The optimal control signal can be obtained by solving the designed optimization problem. The optimal control signal is related to the discrete control action. In addition, mapping between the continuous control signal and the discrete control action is designed. Third, a semi-physical experimental platform is built to verify the proposed topology and control method. The simulation model and experiment platform are built to verify the correctness of the new structure and its control method. The results obtained show that the new topology can work effectively.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.67-69
• /
• 2004

This thesis attempts to investigate and analyze the structure of educational simulation devices implemented thus far. conducting a close analysis of their strengths and weaknesses. On this basis the author Presents and implements a new method of simulation, and continuously upgrades it for increased stability and convenience. The most important aspects of the educational simulation device described in this thesis are: first removing the editing function (scenarios. single line diagrams, and point DB), which the instructor finds time-consuming and inconvenient to use; second, developing and installing the program so as to calculate electric power flow that can measure fluctuations measurements after changing the system status; and third. implementing a Client/server mode to build a system that will make it possible to train many people at a time in remote locations. When compared to simulation devices of the Psst. the greatest differences are that algorithm-based scenarios make scenario inputs unnecessary. and that the amount of work required for the point DB and single line diagrams were minimized.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.10
• /
• pp.80-87
• /
• 2021

Our study introduces an improved modular agricultural platform to provide convenience to agricultural workers. We upgrade the platform design in three parts, namely, by adding a 458 pattern tire, electricity control, and four-wheel steering function, to improve the platform performance. Results showed that the upgrades enhanced the platform performance and reduced its overall weight as compared with the existing platform. To demonstrate the performance of our improved platform, we conducted five types of experiments with respect to the climbing angle, variable width, attitude control, speed, and obstacle passing.

• Korean Journal of Occupational Health Nursing
• /
• v.28 no.2
• /
• pp.104-113
• /
• 2019

Purpose: This study aimed to investigate the factors affecting general hospital nurses' intention to stay in their jobs. Methods: A descriptive research design was used with a convenience sample of 286 nurses. Data were collected from March 15 to April 14, 2017using self-reported questionnaires and analyzed by descriptive statistics, t-test, analysis of variance, Pearson's correlation coefficient, and multiple regression analysis using the SPSS/WIN 21.0 program. Results: The mean scores for intention to stay, resilience, and emotional labor were 5.28 out of 8, 57.40 out of 100, and 3.23 out of 5, respectively. Intention to stay was positively correlated with overall career (r=.30), workplace (r=.18), shift work (r=-.20), position (r=.28), salary (r=.13), job satisfaction (r=.51), hospital satisfaction (r=.46), and resilience (r=.41). Factors influencing the intention to stay were job satisfaction and resilience, which explained 28% of the variance. Conclusion: Overall career, job satisfaction, and resilience are critical factors affecting general hospital nurses' intention to stay. Based on the findings of this study, efforts to improve nurses' job satisfaction and resilience should be implemented to mitigate the loss of this expert group among healthcare professionals.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.14 no.4
• /
• pp.17-26
• /
• 2018

Connected car plays an important role on Intelligent Transport System (ITS). ITS is able to secure drivers' convenience and safety, however, the overall system can be threatened by hacking attempt. Blockchain is one strong candidate of the remedy to promote the security of the ITS network. However, there will be many challenges to adopt previously proposed blockchain technologies to ITS. This work presents a new ITS structure based on blockchain technology. Proposed scheme includes three major layers. The first layer is central manager which is initiated once to register a certain connected car. The third layer is RSU (Road Side Unit) layer which exploits PoS (Proof of Stake) for consortium blockchains and retains real-time information. In addition, this layer performs block expiration based on timers to maintain manageable block length. In the second layer, the generated blocks of the third layer without expiration are housed as private blockchains. We finally demonstrate possible merits of newly proposed scheme.

• Journal of Korean Public Health Nursing
• /
• v.33 no.1
• /
• pp.98-108
• /
• 2019

Purpose: The purpose of this study was to identify factors influencing care workers' patient safety behaviors (PSB), we hoped to provide baseline data for its activation. Methods: The subjects of this study were chosen by convenience sampling, which included 114 care workers at long term care facilities. Data were collected from August 22 to October 10, 2018. The gathered data were analyzed using the SPSS program, which was used to Cronbach's alpha, descriptive statistics, t-test, ANOVA, Pearson correlation coefficient and stepwise regression. Results: The care workers' average PSB was at 7.81 points, patient safety culture (PSC) 3.86 points and safety of long-term care facilities 7.07. PSB positively correlated with safety of facilities(r=.802, p<.001) and PSC(r=.558, p<.001). Work attitude and satisfaction of job were explained 35.1% of the PSB. Conclusion: Administrators of long term care facilities should be interested in patient safety culture and improving job satisfaction of care workers in order to improve patient safety behaviors.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.22 no.6
• /
• pp.1363-1374
• /
• 2012

The number and use of Internet connected devices has dramatically increased in the last several years. Therefore many services synchronizing data in real-time is increasing such as mail, calendar and storage service. This service provides convenience to users. However, after devices are seized, the data could be changed because of characteristic about real-time synchronization. Therefore digital investigation could be difficult by this service. This work investigates the traces on each local device and proposes a method for the preservation of real-time synchronized data. Based on these, we propose the procedures of real-time synchronization data.

• Journal of radiological science and technology
• /
• v.43 no.6
• /
• pp.461-467
• /
• 2020

In the field of nuclear medicine, errors are sometimes generated because the assessment of the uniformity of gamma cameras relies on the naked eye of the evaluator. To minimize these errors, we created an artificial intelligence model based on CNN algorithm and wanted to assess its usefulness. We produced 20,000 normal images and partial cold region images using Python, and conducted artificial intelligence training with Resnet18 models. The training results showed that accuracy, specificity and sensitivity were 95.01%, 92.30%, and 97.73%, respectively. According to the results of the evaluation of the confusion matrix of artificial intelligence and expert groups, artificial intelligence was accuracy, specificity and sensitivity of 94.00%, 91.50%, and 96.80%, respectively, and expert groups was accuracy, specificity and sensitivity of 69.00%, 64.00%, and 74.00%, respectively. The results showed that artificial intelligence was better than expert groups. In addition, by checking together with the radiological technologist and AI, errors that may occur during the quality control process can be reduced, providing a better examination environment for patients, providing convenience to radiologists, and improving work efficiency.

• The Journal of Asian Finance, Economics and Business
• /
• v.8 no.2
• /
• pp.1135-1146
• /
• 2021

The paper aims to examine the relationship between various types of motivation and satisfaction as well as turnover intentions of public university lecturers. Intrinsic motivation is found to affect both satisfaction and turnover, while for extrinsic motivation, only one type has a significant effect on satisfaction. The web-based questionnaire with convenience sampling was chosen to approach target respondents. Data was collected by sending a link of the questionnaire to the lecturers' email. There were 700 questionnaires collected. Of which 681 valid responses, after screening out unusual questionnaires. In order to fulfill these aims, the authors employed structural equation modeling with maximum likelihood method supported by AMOS software with 681 valid samples. The evidence confirms the high correlation between intrinsic motivation and satisfaction for university lecturers which has been shown in previous studies. With regard to extrinsic motivation, extrinsic regulation (material) is found to have a positive influence on satisfaction, meaning financial rewards and job security will lead to his contentment while introjected regulation is a source of dissatisfaction. The results also demonstrate that intrinsic motivation is negatively correlated with turnover intentions. A person who is interested in the job itself is less likely to leave his or her job due to a keen passion for it.

• Journal of Korean Public Health Nursing
• /
• v.35 no.2
• /
• pp.297-309
• /
• 2021

Purpose: This study aimed to identify factors relating to COVID-19 knowledge and resilience that impact elementary school health teacher performance at infection control. Methods: This study adopted a cross-sectional design. Data were collected from 140 elementary school health teachers by convenience sampling. Collected data were analyzed using SPSS Ver. 26.0. Results: Mean scores were as follows COVID-19 knowledge 17.99±2.37 (range 0-23), resilience 120.36±16.90 (range 30-150), and performance at infection control 85.91±10.07 (range 25-100). A positive correlation was observed between resilience and infection control performance (r=0.57, p<.001). Factors found to influence participant performance at infection control were resilience (𝛽=0.54, p<.001) and two categories of educational experience: 11-15 years (𝛽 = 0.24, p=.011) and more than 20 years (𝛽=0.29, p=.044). Conclusion: These results indicate the resilience of elementary school health teachers positively affects their performance at infection control. Generally, both age and work experience affected ability to perform infection control. Therefore, this study supports the need to develop programs to increase the resilience of elementary school health teachers according to infection control performance and age.