• Journal of Power Electronics
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• v.11 no.4
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• pp.606-611
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• 2011

Power electronics is a key technology for electric, hybrid, plug-in hybrid, and fuel cell vehicles. Typical power electronics converters used in electric drive vehicles include dc/dc converters, inverters, and battery chargers. New semiconductor materials such as silicon carbide (SiC) and novel topologies such as the Z-source inverter (ZSI) have a great deal of potential to improve the overall performance of these vehicles. In this paper, a Z-source inverter for fuel cell vehicle application is examined under three different scenarios. 1. a ZSI with Si IGBT modules, 2. a ZSI with hybrid modules, Si IGBTs/SiC Schottky diodes, and 3. a ZSI with SiC MOSFETs/SiC Schottky diodes. Then, a comparison of the three scenarios is conducted. Conduction loss, switching loss, reverse recovery loss, and efficiency are considered for comparison. A conclusion is drawn that the SiC devices can improve the inverter and inverter-motor efficiency, and reduce the system size and cost due to the low loss properties of SiC devices. A comparison between a ZSI and traditional PWM inverters with SiC devices is also presented in this paper. Based on this comparison, the Z-source inverter produces the highest efficiency.

• Journal of KIISE:Software and Applications
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• v.36 no.1
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• pp.45-53
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• 2009

In these days GUI components are recognized as the important driving elements to the successful software development. Thus they must be verified. In practice, however, GUI testing for verifying the GUI components needs lots of time and high costs. Test automation for GUI testing is a promising solution to save those expenses. In this paper, we discuss some issues considered to perform GUI testing and suggest a new method that improve the GUI test case generation method based on our previous 'record & playback' approach. For this, we suggest the event generation method using the 'spy' technique and the scenario generation method that generates effectively a lot of scenarios with the generated events. In turn we describe how to create GUI test cases from the generated scenarios.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.5
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• pp.1-10
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• 2016

Drought is a slow-varying natural hazard that is characterized by various factors such that reliable drought forecasting along with uncertainties estimation has been a major issue. In this study, we proposed a stochastic simulation technique based scheme for providing a set of drought scenarios. More specifically, this study utilized a nonstationary Hidden markov model that allows us to include predictors such as climate state variables and global climate model's outputs. The simulated rainfall scenarios were then used to generate the well-known meteorological drought indices such as SPI, PDSI and PN for the three dam watersheds in South Korea. It was found that the proposed modeling scheme showed a capability of effectively reproducing key statistics of the observed rainfall. In addition, the simulated drought indices were generally well correlated with that of the observed.

• Journal of the Korea Safety Management & Science
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• v.16 no.4
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• pp.159-165
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• 2014

For the hydrogen economy system being tried starting with the 21st century, the fields that was not dealt with so far, such as the safety measure for large leakage accidents, the safety problem at infrastructures like a hydrogen station, the safety problem in terms of automobiles depending on introduction of hydrogen cars, the safety problem in a supply for homes like fuel cells, etc., are being deeply reviewed. In order to establish a safety control system, an essential prerequisite in using and commercializing hydrogen gas as an efficient energy source, it is necessary to conduct an analysis, such as analysis of hydrogen accident examples, clarification of physical mechanisms, qualitative and quantitative evaluation of safety, development of accident interception technologies, etc. This study prepared scenarios of hydrogen gas leakage that can happen at hydrogen stations, and predicted damage when hydrogen leaks by using PHAST for this.

• Environmental Engineering Research
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• v.24 no.4
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• pp.618-629
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• 2019

Along with growing population and economic development, increasing waste generation rates in developing countries have become a major issue related to the negative impacts of waste management on the environment. Currently, the business-as-usual waste management practices in Myanmar are largely affecting the environment and public health. Therefore, this study developed an alternative approach to waste management for reducing the environmental impacts in Myanmar by highlighting the greenhouse gas (GHG) emissions from business-as-usual practices and three proposed scenarios during 2018-2025. The calculation methods of the Intergovernmental Panel on Climate Change and Institute for Global Environmental Strategies were used for estimating the GHG emissions from waste management. It was estimated that the current waste management sector generated approximately 2,000 gigagrams of CO₂-eq per year in 2018, trending around 3,350 Gg of CO₂-eq per year in 2025. It was also observed that out of the proposed scenarios, Scenario-2 significantly minimized the environmental impacts, with the lowest GHG emissions and highest waste resource recovery. Moreover, the GHG emissions from business-as-usual practices could be reduced by 50% by this scenario during 2018-2025. The target of the similar scenario could be achieved if the local government could efficiently implement waste management in the future.

• Journal of Korea Game Society
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• v.6 no.4
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• pp.89-95
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• 2006

The game has both directionalities that users are to choose and act accordingly. In this regard, the game scenario goes beyond just conveying the story, and trains users and guide them in playing the Same. However, this Same scenario is huge in size and every event is linked with each other so that it was rather difficult to have it made in practice. A study proposes that a script, the minimum unit, is built into a database, and based on which, quests are made, then the resulting quests are built back into a database. Scripts are classified into text, graphic and sound type and these are positioned in accordance with the quest structure. With this method, one can re-use the existing scenarios and can overcome the negatives of irregular qualities of scenarios.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.26-32
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• 2013

The best way to prevent major occupational accidents is prohibiting use of hazardous substances such as flammable gas, toxic gas whereas using alternative substances that ensured safety. but if there are no economic efficiency and substituting technologies of alternative substances, the best way is preparing to prevent accidents thoroughly. Therefore, this study has developed and selected release scenarios to use and apply for consequence analysis and emergency action plan for HF charging process of chemical plants that have HF release accidents and high probability of release accidents.

• Journal of Information Science Theory and Practice
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• v.8 no.1
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• pp.6-19
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• 2020

When information professionals deal with other disciplines in the course of digital humanities projects, they often assume that they are dealing with 'needful users' who have an 'information gap' to fill. This paper argues that the traditional view that information/knowledge is transferred from an information specialist donor to a domain specialist receiver is no longer appropriate in the digital humanities context, where the gap-and-search (or gap-and-filler) approach to information has given way to more direct, explorative engagement with information. The paper asks whether information science and the practising profession are ready for this paradigm shift and examines information science conservatism in two common collaboration scenarios, library support and digital development. It is shown that information science theory still assumes a traditional donor role in both scenarios. How information scientists deal with conservatism in practice is discussed in the example of the Prior project, in which the information science team exerted an ambiguous, hybrid approach with both conservative and non-conservative elements. Finally, two rather hypothetical answers are offered to the question of how information professionals should approach scholarly collaboration in the digital humanities context, where users have ceased to be supplicants. From a purely pragmatic perspective, information scientists need to shift their focus from information needs to research practices and the implications of these practices for digital information systems. More fundamentally, the emergence of digital humanities challenges information professionals to transform information systems designed for searching into digital objects that can be explored more freely by the digital humanities community.

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

• Electronics and Telecommunications Trends
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• v.34 no.6
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• pp.51-60
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• 2019

As a way to further expand and enable the 5G ecosystem, the $3^{rd}$ Generation Partnership Project (3GPP) is considering the development of a 5G new radio (NR)-based non-terrestrial network (NTN). These NTNs are expected to provide ubiquitous 5G services to user's equipment (especially, in Internet of Things/machine-type communications (IoT/MTC) public safety, and critical communications) by extending service coverage to areas not covered by 5G terrestrial networks. To this end, this NTN is developing scenarios to provide 5G services using spaceborne vehicles, such as geosynchronous and low-Earth orbit satellites, and airborne vehicles, such as unmanned aircraft systems, including high-altitude pseudo-satellites. In addition, various technologies are being studied to satisfy new requirements not considered in 5G NR, such as long propagation delay time, large cell coverage, large Doppler effect, and base station movement. In this paper, we present the scenarios, requirements, technical issues and solutions, and standardization planning for NR-based NTN in 3GPP.