• Journal of the Korean Society for Precision Engineering
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• v.34 no.4
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• pp.265-272
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• 2017

Velocity ripple in manufacturing processes reduces productivity and limits the precision of the product. In practice, the frequency and phase of velocity ripples always change minutely, which makes it impossible to compensate for the ripple by simply inserting an opposite feed-forward signal in the system. In this study, an active-phase compensation algorithm was developed to enable the velocity-ripple controller to track the phase change of the ripples in real time. The proposed controller can compensate for the velocity ripple whatever its cause, including disturbance by the torque ripple. The algorithm consists of three functional modules: the velocity-ripple extractor, the synchronized integrator, and the phase shifter. Experimental results showed that the proposed controller clearly reduces velocity ripples with phase variation.

• Journal of Engineering Education Research
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• v.23 no.6
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• pp.3-16
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• 2020

This study aims to introduce the ENACT model, which is a systematic teaching-learning model for cultivating social responsibility of science and engineering college students, and to discuss its educational implications. For the development of the ENACT model, we conducted extensive literature reviews on RRI, STEM education, and science and technology studies (STS). In addition, we examined exemplary overseas education programs emphasizing social responsibility of scientists/engineers and citizens. The ENACT model consists of five steps; 1) Engage in SSIs, 2) Navigate SSIs, 3) Anticipate consequences, 4) Conduct scientific and engineering practice, and 5) Take action. This model links Socioscientific Issues (SSI) education with engineering education, dividing the major elements of social responsibility education for scientists and engineers into the dimensions of epistemology and praxis, and reflected them in the model. This effort enables science and engineering college students to pursue more responsible and sustainable development by carrying out the responsible problem-solving process based on an understanding of the nature of science and technology. We plan to implement ENACT model based programs for science and engineering college students and to examine the effects.

• Journal of Korean Society of Forest Science
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• v.103 no.2
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• pp.203-210
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• 2014

The purpose of this study was to investigate the effect of experimental warming using infrared lamps on seed germination and seedling survival rate of Pinus densiflora and Abies holophylla. The air temperature of warmed plots had been automatically maintained 3 higher than control plots. The percent germinations (%) of the two coniferous species were higher in warmed plots than in control plots, however a significant difference appeared only in A. holophylla. In addition, P. densiflora and A. holophylla showed the shorter mean germination time (days), higher germination rate ($seed{\cdot}day^{-1}$) and germination energy (%) in warmed plots than in control plots. A. holophylla showed a higher seedling mortality rate in the warmed plots than in control plots because of increased air and soil temperatures and decreased soil moisture. However, seedling survival rate of P. densiflora showed no significant difference by experimental warming. In the future, changed air and soil temperatures and soil moisture due to global warming will induce a variety of changes in seed germination and survival rate of tree species in nursery culture. Therefore, it is necessary to establish adaptation strategies that improve techniques in nursery culture against global warming.

• Journal of Mechanical Science and Technology
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• v.14 no.11
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• pp.1250-1256
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• 2000

Rubbing occurs when a rotor contacts with a stator during whirling motion of the rotor. Compared to full annular rub, partial rub against a nonrotating part is more common in practice. In this study, several partial rubbing phenomena of superharmonic and subharmonic vibrations and jump phenomenon are demonstrated experimentally for the cases of light and heavy rub for a flexible rotor. The orbit patterns of forward or backward whirling are also calculated using directional spectrum analysis. The occurrence if subharmonic vibration during heavy rub is demonstrated as one impact per two rotations both experimentally and numerically.

• Journal of Science Education
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• v.43 no.3
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• pp.363-381
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• 2019

This study aims to suggest an inclusive conceptual framework for the Nature of Technology (NOT) by examining literature and researches regarding NOT and then to analyze the conceptions of the students in Science and Engineering Department of a college based on the NOT framework. Findings are as follows: First, the conceptual framework of the NOT developed from the study has the five domains of NOT, which are Technology as Artifacts, Technology as Knowledge, Technology as Practice, Technology as History, and Technology as a part of Society. Second, the participants' conceptions of the NOT emphasize on three domains of the Technology as Practice (26.4%), Technology as a part of Society (25.8%), and Technology as Knowledge (24.3%) among the five domains of the NOT. Third, according to the microanalysis of the students' conceptions regarding NOT, students in Science and Engineering Department of a college possess concrete and various views of the NOT even though NOT is abstract and complex ideas. Specifically, they seem to recognize the NOT as a product of process and ability to utilize the technology for convenience of life.

• Journal of dental hygiene science
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• v.13 no.4
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• pp.410-417
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• 2013

This research surveyed 324 college students majored dental hygiene in Gwangju and Chonnam province to analyze their awareness and degree of practice about infection control. Through the study for recognition about infectious disease related with the grade, the sophomore students are the group who is the most aware. In addition, the study shows students who experienced teeth cleaning have high degree of awareness (p<0.05). The research of perception about infectious disease based on experiences for vaccinations and education about infection prevention says hepatitis B has the highest rate when it comes to level of occurrence risk and tuberculosis and acquired immune deficiency syndrome are the lowest (p<0.05). According to the research, the group who had vaccination, knowledge about infection prevention and experience for scaling shows high practice rate for hand washing according to whether students receive protective inoculation or not. Depending on what the result were, since student learned about infection control has high degree of recognition and practice about infection management if we could emphasize the importance to students through regulative education about infection control and then increase the degree of practice, it would make big contributions to the effective infection control.

• Journal of Information Science Theory and Practice
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• v.12 no.2
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• pp.79-95
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• 2024

The new AI based conversational chatbot, ChatGPT, launched in November 2022, is causing a stir. There are many opinions about this being a 'threat or a promise,' and thus it is important to understand what has been said about this tool and, based on the growing literature that has emerged on the subject, demystify its effective impact on society. To analyse this impact, a systematic literature review with the support of the preferred reporting items for systematic reviews and meta-analysis protocol was used. The data, scientific documents, were collected using the main scientific databases - SCOPUS and Web of Science - and the results were presented based on a bibliometric and thematic exploration of content. The main findings indicate that people are increasingly using this chatbot in more diverse areas. Therefore, this study contributes at the practical level, aiming to enlighten people in general - both in professional and personal life - about this tool and its impacts. Also, it contributes at the theoretical level, which involves expanding understanding and elucidation of the impacts of ChatGPT in different areas of study.

• Journal of Veterinary Science
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• v.22 no.6
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• pp.74.1-74.13
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• 2021

Tissue engineering has been extensively investigated and proffered to be a potential platform for novel tissue regeneration. The utilization of mesenchymal stem cells (MSCs) from various sources has been widely explored and compared. In this regard, MSCs derived from bone marrow have been proposed and described as a promising cell resource due to their high yield of isolated cells with colony-forming potential, self-renewal capacity, MSC surface marker expression, and multi-lineage differentiation capacities in vitro. However, there is evidence for bone marrow MSCs (BM-MSCs) both in vitro and in vivo from different species presenting identical and distinct potential stemness characteristics. In this review, the fundamental knowledge of the growth kinetics and stemness properties of BM-MSCs in different animal species and humans are compared and summarized. Finally, to provide a full perspective, this review will procure results of current information studies focusing on the use of BM-MSCs in clinical practice.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.939-942
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• 1989

Most of systems are included nonlinear characteristics in practice. One might be faced with difficulties when problems of nonlinear systems are solved. In this paper we present a formal linearization method of nonlinear systems by using the trigonometric Fourier expansion on the state space considering easy inversion. An error bound, an application, and a compensation of this method are also investigated.

• Wind and Structures
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• v.37 no.2
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• pp.105-115
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• 2023

Structural design includes calculation of the wind speed as one of the major steps in the design process for wind loading. Accurate determination of design wind speed is vital in achieving safety that is consistent with the economy of construction. It is noticeable that many countries and regions such as Hong Kong, Japan and Australia regularly make amendments to improve the accuracy of wind load estimations for their wind codes and standards. This study compares the latest Hong Kong wind code published in 2019, which is generally known as the Code of Practice on Wind Effects in Hong Kong - 2019, with the latest revision of the AIJ Recommendations for Loads on Buildings - 2015 (Japan), and the Australian/New Zealand Standard, AS/NZS 1170.2:2021. The comparisons include the variations between the design wind speed and the vertical profiles of wind speed multipliers. The primary purpose of this study was to show any differences in the basic design wind speed and exposure factor estimations among the three economies located in the Western Pacific Ocean. Subsequently, the reasons for such underlying variations between the three documents, are discussed, together with future development trends.