• Journal of Power Electronics
• /
• v.2 no.4
• /
• pp.288-296
• /
• 2002

In this paper, a high frequency transformer - assisted auxiliary active resonant commutated snubber (HFTA-ARCS) for voltage source soft switching pulse width modulated power conversion circuits is presented. A three phase voltage source type soft switching inverter incorporating HFTA-ARCS circuits in its three bridge legs can reduce current rating of auxiliary active power switches and has sensorless simplified control scheme which any specified boost current management is not required for soft switching. Its operation principle and digital control scheme are described and a practical design method of circuit parameters on this HFTA-ARCS circuit is also introduced on the basis of computer simulation. Moreover, this space voltage vector modulated soft switching inverter system with DSP-based digital control scheme Is discussed and its effectiveness is proved on the basis of performance evaluations. The operating performances of this inverter system are also compared with those of conventional three-phase hard switching inverter under practical conditions of specified parameters.

• Industrial Engineering and Management Systems
• /
• v.13 no.2
• /
• pp.163-171
• /
• 2014

Under amazing increase in markets and certain demand on qualified service in the delivery system, global logistic optimization is becoming a keen interest to provide an essential infrastructure coping with modern competitive prospects. As a key technology for such deployment, we have been engaged in the practical studies on vehicle routing problem (VRP) in terms of Weber model, and developed a hybrid approach of meta-heuristic methods and the graph algorithm of minimum cost flow problem. This paper extends such idea to multi-depot VRP so that we can give a more general framework available for various real world applications including those in green or low carbon logistics. We show the developed procedure can handle various types of problem, i.e., delivery, direct pickup, and drop by pickup problems in a common framework. Numerical experiments have been carried out to validate the effectiveness of the proposed method. Moreover, to enhance usability of the method, Google Maps API is applied to retrieve real distance data and visualize the numerical result on the map.

• Proceedings of the KSRS Conference
• /
• 2002.10a
• /
• pp.191-196
• /
• 2002

From this year, KIGAM, one of Korean government-supported research institutes, has started new national program for digital geologic/natural resources infrastructure building. The goal of this program is to prepare digitally oriented infrastructure for practical digital database building, management, and public services of numerous types of paper maps related to geo-scientific resources or geologic thematic map sets: hydro-geologic map, applied geologic map, geo-chemical map, airborne radiometric/magnetic map, coal geologic map and off-shelf bathymetry map and so forth. As for digital infrastructure, several research issues in this topic are composed of: ISP (Information Strategy Planning), geo-framework modeling of each map set, pilot database building, cyber geo-mineral directory service system, and web based geologic information retrieval system upgrade which services Korean digital geologic maps scaled 1:50K. In this study, UML (Unified Modeling Language)-based data modeling of geo-data sets by and in KIGAM, among them, is mainly discussed, and its results are also presented in the viewpoint of digital geo-modeling ISP. It is expected this model is further progressed with the purpose of being a guidance or framework modeling for geologic thematic mapping and practical database building, as well as other types of national thematic map database building.

• Journal of Digital Convergence
• /
• v.17 no.3
• /
• pp.55-61
• /
• 2019

Multimedia materials were developed to creative children's songs to elementary schoolers so as to improve favorable personality. To this end, we selected elementary school students to select appropriate songs for the cultivation of humanity, and produced multimedia including various image materials such as animation, documentary, chorus, dance performances, and interviews. Above all, we have created a teaching - learning process and presented the program so that teachers can easily guide students to agitation. As a result, the change of personality of elementary school students was positively shown through sway broadcasting, and I tried to give practical examples of practical application for cultivation of creativity and personality that should be emphasized at elementary school.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.6
• /
• pp.141-149
• /
• 2019

This study was attempted to contribute to enhancing the quality of practical education by using Q-methodology to find out how nursing students cope with a mistake during clinical practice. From October 3rd to 26th, 2016, 30 Q-statements were selected through in-depth interviews and prior papers to identify response patterns for mistakes in the 3rd to 4th grade of the Department of Nursing at K University. The analysis using the QUANL program has four types. the first type was named the frankness type, the second type was named the forwardness type, the third type was named the evasion type, the fourth type was named the anxiousness type. In this paper we proposed that the practical guidance instructor and the field instructor need to understand the individual recognition style of each student and to develop coping strategies considering the individuality and to cooperate with education and guidance. In addition, in order to establish a positive cognitive formation and coping method in case of a mistake, it is necessary to educate management about mistakes in systematic nursing student clinical practice.

• Nuclear Engineering and Technology
• /
• v.54 no.5
• /
• pp.1845-1850
• /
• 2022

In-vessel corium retention (IVR) during external reactor vessel cooling (ERVC) is a key severe accident management strategy adopted in advanced nuclear power plants. The injection of nanofluids has been regarded as a means of enhancing CHF when using the IVR-ERVC strategy to safeguard high-power nuclear reactors. However, a critical practical concern is that various types of debris flowing from the contaminant sump during operation of an ERVC system might degrade CHF enhancement by nanofluids. Our objective here was to experimentally assess the viability of nanofluid use to enhance CHF in practical ERVC contexts (e.g., when fluids contain various types of debris). The types and characteristics of debris expected during IVR-ERVC were examined. We performed pool boiling CHF experiments using nanofluids containing these types of debris. Notably, we found that debris did not cause any degradation of the CHF enhancement characteristics of nanofluids. The nanoparticles are approximately 1000-fold smaller than the debris particles; the number of nanoparticles in the same volume fraction is 1 billion-fold greater. Nanofluids increase CHF via porous deposition of nanosized particles on the boiling surface; this is not hindered by extremely large debris particles.

• Asia-Pacific Journal of Business
• /
• v.12 no.3
• /
• pp.295-328
• /
• 2021

Purpose - This study reviewed domestic empirical studies on abusive supervision published from 2009 to 2020 and summarized the accumulated results. In particular, this study classified previous studies on abusive supervision as antecedents (supervisor characteristics, subordinate characteristics, and contextual factors) and outcome variables (cognition/awareness, affection/emotion, attitude, behavior, and others). Based on the results, this study suggested potential issues of previous studies and future directions for abusive supervision. In addition, this study proposed the academic and practical implications and limitations. Design/methodology/approach - The domestic studies on abusive supervision can be divided into antecedents and outcome variables, and each study was organized into the characteristics of the supervisor, subordinate, and situational characteristics, and the resultant variables were divided into cognition/awareness, affection/emotion, attitude, behavior, and others. Finding - Prior studies on abusive supervision had several limitations in obtaining clear results with individual characteristics or fragmented approaches at the organizational level. In the future, more comprehensive approaches will be needed. Research implications or Originality - This study will provide academic and practical implications for future research on abusive supervision by deepening an understanding of the negative consequences of abusive supervision.

• International Journal of Advanced Culture Technology
• /
• v.11 no.2
• /
• pp.36-43
• /
• 2023

This study aims to derive discourse's linguistic meaning, production method, and social practice implications by analyzing news reports on de-facility for people with disabilities. To this end, the discourse was analyzed by applying Fairclough's framework of critical discourse analysis. The subject of analysis is a news article on the de-facility of the disabled on the N portal site, and the analysis period is one year, from January 1 to December 31, 2022. First, as a result of the study, the surface meaning of the news discourse on the de-facility for disabled people was ideological through the seriousness of the problem for disabled people, the poor environment, and the policy of de-facility for disabled people separated from reality. Second, the social meaning of the de-facility news discourse for disabled people appeared from a realistic perspective, such as the structural cause of the problem for disabled people and the need for sensible government policies and measures to practice de-facility for disabled people. Finally, the socio-cultural practical implications of the de-facility news discourse for people with disabilities proposed the development of a systematic and realistic de-facility management manual for the disabled, practical government policy support, and changes in self-support perception for disabled people. The results of this study are expected to help find an alternative direction to reduce the gap between actual policies for de-facility for disabled people and practice in the field in the future.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.31 no.2
• /
• pp.95-99
• /
• 2023

As our whole society has become increasingly aware of safety and emphasizes the importance of preventing safety accidents, the airline cabin service sector is also facing a strong demand to improve practical system for aviation safety education. In this regard, the development of appropriate safety education programs and the getting of human resources who can develop and operate such programs are becoming key issues. This study aims to provide academic and practical implications for safety education and training in airline cabins by reconfirming the importance and direction of safety education in the context of airline cabin services, and by specifying and establishing qualification requirements for personnel who develop and operate such safety programs. To this end, we review the content that should be included in safety training programs, the qualifications required of developers, managers, instructors, and examiners who develop or operate such programs, and how safety training programs can be continually improved as relevant conditions change in the future. In addition, we have also suggested ways to train appropriate managers, instructors, and examiners, including improving the compensation system for them, and how to effectively manage trainees. In order to secure a higher level of aviation safety in the future, it will be necessary to continue research on the development of more diverse and high-quality aviation safety education programs and the training of related personnel.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.05a
• /
• pp.265-266
• /
• 2021

Recently, the importance of disaster prevention has emerged as serious accidents have occurred frequently, in which workers died or seriously injured at industrial sites. In response, the government enacted the 'Act on the Punishment of Major Disasters' to strengthen the responsibility, punishment intensity, and regulation of business owners for accidents at the site. In particular, the construction industry accounts for a large proportion of serious accidents, so safety levels need to be raised through on-site management. This study aims to reduce the occurrence of disasters at construction sites and to improve the work efficiency of safety managers. To derive detailed elements of the safety manager's work, domestic and overseas cases were investigated. The derived items were analyzed for the difficulty and preventive effects of the work through a survey of experts, and they will contribute to disaster prevention by presenting tasks to be focused and suggesting ways to improve inefficient tasks.