• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.6
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• pp.410-420
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• 2016

The geometric dimension and shape of microchannels that are formed during surface texturing are widely studied for applications in flow control, and drag and friction reduction. In this research, a new method for controlling the deformation of U channels during micro-rolling-based surface texturing was developed. Since the width of the U channels is almost constant, controlling the depth is essential. A calibration procedure of initial rolling gap, and proportional-integral PI controllers and a linear interpolation have been applied simultaneously to control the depth. The PI controllers drive the position of the pre-U grooved roll as well as the rolling gap. The relationship between the channel depth and rolling gap is linearized to create a feedback signal in the depth control system. The depth of micro channels is studied on A2021 aluminum lamina surfaces. Overall, the experimental results demonstrated the feasibility of the method for controlling the depth of microchannels.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.3-8
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• 1998

Using GIS and socio-economical data the relationship between human activities and global environmental change Is Analysed from the view point of food productivity and CO2 emission. Under the assumption that the population problem, the food problem and global warming due to energy consumption can be stabilized through managing land use, impacts of human activities such as consumption of food, energy and timber on global environment changes, and global population capacity are Analysed using developed system dynamics model in the research. In the model the world is divided into two groups: OECD countries and the others. Used global land use data set Is land cover map derived from satellite data, and potential distribution of arable land is estimated by the method of Clamor and Solomon which takes into consideration spatial distribution of climate data such as precipitation and evapotranspiration. In addition, impacts of CO2 emission from human activities on food production through global warming are included in the model as a feedback. The results of the analysis for BaU scenario and Toronto Conference scenario are similar to the results of existing models. From the result of this study, the human habitability in 2020 is 8 billion people, and CO2 emission in 2020 based on BaU Scenario and on Toronto Scenario is 1.7 and 1.2 times more than the 1986's respectively. Improving spatial resolution of the model by using global data to distribute the environmental variables and sauce-economical indices is left for further studies.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.72-80
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• 2018

Combustion instabilities are caused by the feedback relationship between heat release perturbations and acoustic pressure oscillations in the combustor. Studies on the combustion instability in an annular combustor have recently received great attention due to the enhanced NOx requirement in aero-engines. In this study, a thermoacoustic network model was developed in order to calculate the acoustic characteristics for various modes in the annular combustor. The network model is combined with flame transfer function(FTF) in order to calculate the stability of the combustor. Numerical results are compared with measurement data.

• The Journal of the Korea Contents Association
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• v.5 no.6
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• pp.264-272
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• 2005

It is generally defined that the trust between members are relayed on the belief of ability and support. The purpose of this study is to make sure that participative decision making effects on productivity of group based on that cooperative relationship could bring the productive improvement. As the results, we could figure out that satisfiable rate of performance feedback and open communication are related with the productivity Especially, an administrative group based on the mutual trust, can meet the level of customer's satisfaction and cultural multiplicity. Setting up the mutual trust is to maximize the ability of members and to derive the motivation of working concentration.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.11
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• pp.1021-1031
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• 2020

This study aims to invest in empirical relationships in a model that becomes the process of Team-Performance due to participation in practical training through causality between Training Effectiveness variables, soft-skill competence, Employee-Creativity, and team performance. This study uses a quantitative approach. The analytical tool used is structural equation modeling (SEM) using AMOS version 23 software. Accidental sampling technique is used to collect the sample. As many as 202 respondents filled up a survey questionnaire with complete and valid answers. This study's results significantly contribute to fill the gap of inadequate empirical evidence that can answer critical questions about the missing link between training and employee-performance, more specifically between training-effectiveness and team-performance. The results showed that practical training would encourage employees' soft-skill competence, improve Employee-Creativity, and improve Team-Performance. Furthermore, training-effectiveness also plays a significant role in enhancing employee-creativity and helping in optimal team-performance. This study also found that the relationship between employee-creativity and team-performance did not show positive and significant results; therefore, empirically, it did not support the hypothesis built in this study. Practical training targeted towards increasing soft-skills and creativity is a fundamental reason which not only aims to contribute toward organizational performance but also provides personal feedback for self-development.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.6
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• pp.1027-1041
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• 2012

This study analyzed middle-aged woman volunteers' evaluations on their volunteering and its implications for the adult life-long education. The subjects were 126 women aged from 35 to 59 who enrolled in the volunteer centers in Busan, Korea. They participated in the survey of the volunteer effects and the factors that made them continue to volunteer. Survey said, middle-aged women volunteers perceived that they got positive feedback from others and themselves and it made them keep doing on volunteering. Based on their volunteering experiences, they reported the personal effects such as positivism, caring, volunteering capacity, industry, maturity and the family member's effects such as positivism and participating in their volunteering. They also mentioned that they had positive and negative effects on family relationship such as family relation reinforcement and being indifferent to their own family. Based on the research findings, it was the emphasized that supports for volunteering of the middle-aged women that helps them to accomplish the developmental tasks in the middle age are necessary. A scheme of linkage between volunteering and the adult life-long education was also dealt with. Finally, the implications on the further studies in the field were discussed.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.168-174
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• 2016

In this paper, current control using PI controller in the synchronous reference frame is analyzed through the relationship among bandwidth, resonance frequency, and sampling frequency in the grid-connected inverter with LCL filter. Stability is investigated by using bode plot in frequency domain and root locus in discrete domain. The feedback variable is the grid current, which is regulated by the PI controller in the synchronous reference frame. System delay is modeled as 1.5Ts, which contains computational and PWM modulator delay. Two resonance frequencies are given at 815 Hz and 3.16 kHz from LCL filter parameters. Sufficient phase and gain margins can be obtained to guarantee stable current control, in case that resonance frequency is above one-sixth of the sampling frequency. Unstable current control is performed when resonance frequency is below one-sixth of the sampling frequency. Analysis results of stability from frequency response and discrete response is the same regardless of resonance frequency. Finally, stability of current control based on theoretical analysis is clearly verified through simulation and experiment in grid-connected inverters with LCL filter.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.5
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• pp.1395-1406
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• 2016

The purpose of this study was to examine the effects of interaction based mother-child art therapy on the change of child and mother's interactions in a child who was in trouble due to attachment problems. The subject in this study was a six-year-old child who faced difficulties in peer relationship building and who were maladjusted to kindergarten because of unstable attachment and negative feedback from his parents. Also, he showed serious problem behaviors at home. The ABA design was adopted among single-subject research designs, and the Target child was observed in the sessions in terms of the subfactors of Marschak's Behavioral Rating Scale to gather data related to the changes of child and mother's interactions. As a result of analyzing the collected data, there were positive changes in all the subfactors that were the child's verbal/nonverbal interactions, the mother's verbal/nonverbal interactions and mother-child interactions. Therefore the interaction based mother-child art therapy that was designed to boost child and mother's interactions was effective at furthering the mother-child interactions of the child with attachment problems.

• Journal of the Korea Society of Computer and Information
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• v.23 no.2
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• pp.117-123
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• 2018

This article is to investigate the possibility that project-based classes introducing mobile phones can replace the monotony of traditional classes led by teachers as well as they can encourage students to take active part in the classes to some extent. The students in groups choose a genre for their own video projects (e.g., movie, drama, news, documentary, and commercial) and produce the video contents using a mobile phone for presentation made at the end of a semester. In the sense that the students are allowed to do video-based mobile phone projects, they can work independently outside of class, where time and space are more flexible and students are free from the anxiety of speaking or acting in front of an audience. A mobile phone project consists of around five stages done both in and outside of the classroom. All of these stages can be graded independently, including genre selection, drafting of scripts, peer review and revision, rehearsals, and presentation of the video. Feedback is given to students. After the presentation, students filled out a survey questionnaire sheet devised to analyze students' responses toward preferences and level of difficulty of the project activity. Finally, proposals are made for introduction of a better mobile phone-based project classes.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.896-904
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• 2017

Lean premixed combustion was successful in meeting current NOx emission regulations. However, these often leads to combustion instability. This phenomena results from the feedback relationship between heat release perturbations and acoustic pressure oscillations in the combustor. Researches on the combustion instability in an annular combustor have recently received great attention due to the enhanced NOx requirement in aero-engines. In this study, the thermoacoustic network model has been developed in order to calculate the acoustics for longitudinal as well as circumferential modes in the annular combustor. The combustion model in the network model is calculated by flame transfer function(FTF). Numerical and analytical results are compared to an measurement data.