• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.368-373
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• 2003

This paper presents a study of low frequencies volume velocity vibration control of a smart panel in order to reduce sound transmission. A distributed piezoelectric quadratically shaped polyvinylidene fluoride (PVDF) polymer film is used as a uniform force actuator and an array of 4$\times$4 accelerometer is used as a volume velocity sensor for the implementation of a single-input single-output con rot system. The theoretical and experimental study of sensor-actuator frequency response function sho vs that this sensor-actuator arrangement provides a required strictly positive real frequency response function below about 900Hz. Direct velocity feedback could therefore be implemented with a limited gain which gives reductions of about 15㏈ in vibration level and about 8 ㏈ in acoustic power level at the (1, 1) mode of the smart Panel. It has been also shown that the shaping error of PVDF actuator could limit he stability and performance of the control system.

• Korean System Dynamics Review
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• v.12 no.4
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• pp.35-62
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• 2011

PFI(Private Finance Initiative) for suppling SOC and public facilities instead of Government Infrastructure Project introduced from 1994. BTO(Build-Transfer-Operate) project had been major type of PFI system from 1994 to 2005. But after changed the Law of PFI on SOC, the BTL project newly introduced. In BTO system, the Government retrieves the investment through the operating income, but in BTL system, the government lease the facilities. As the BTO and BTL projects are widely adopted and implemented to ease the fiscal burden of government, but it has caused the tremendous fiscal burden each year over the period operation. Therefore this study attempted to analyze the question, that is, why government fiscal burden tipping? Hence, this paper, compares the difference of business structure between BTO and BTL project and explore the vicious and virtuous business structure, with the method of circular causal loop analysis. As a result, it has shown that there are some positive feedback and negative feedback loops cause the tipping and easing of government fiscal burden.

• Korean Medical Education Review
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• v.23 no.2
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• pp.90-103
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• 2021

This study examined the current status of the medical professionalism curriculum in Korea to suggest a plan to move towards the formation of a professional identity. Professionalism education data from 28 Korean medical schools were analyzed, including the number of courses, required or elective status, corresponding credits, major course contents, and teaching and evaluation methods. Considerable variation was found in the number of courses and credits in the professionalism curriculum between medical schools. The course contents were structured to expand learners' experiences, including the essence and knowledge of professionalism, understanding of oneself, social interaction with others, and the role of doctors in society and the healthcare system. The most common teaching methods were lectures and discussions, while reflective writing, coaching, feedback, and role models were used by fewer than 50% of medical schools. Written tests, assignments and reports, discussions, and presentations were frequently used as evaluation methods, but portfolio and self-evaluation rates were relatively low. White coat ceremonies were conducted in 96.2% of medical schools, and 22.2% had no code of conduct. Based on the above results, the author suggests that professional identity formation should be explicitly included in learning outcomes and educational contents, and that professional identity formation courses need to be added to each year of the program. The author also proposes the need to expand teaching methods such as reflective writing, feedback, dilemma discussion, and positive role models, to incorporate various evaluation methods such as portfolios, self-assessment, and moral reasoning, and to strengthen faculty development.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.75.4-75.4
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• 2019

We present a quantitative analysis of the relationship between the gas dynamics and star formation history of DDO 210 which is an irregular dwarf galaxy in the local Universe. We perform profile analysis of an high-resolution neutral hydrogen (HI) data cube of the galaxy taken with the large Very Large Array (VLA) survey, LITTLE THINGS using newly developed algorithm based on a Bayesian Markov Chain Monte Carlo (MCMC) technique. The complex HI structure and kinematics of the galaxy are decomposed into multiple kinematic components in a quantitative way like 1) bulk motions which are most likely to follow the underlying circular rotation of the disk, 2) non-circular motions deviating from the bulk motions, and 3) kinematically cold and warm components with narrower and wider velocity dispersion. The decomposed kinematic components are then spatially correlated with the distribution of stellar populations obtained from the color-magnitude diagram (CMD) fitting method. The cold and warm gas components show negative and positive correlations between their velocity dispersions and the surface star formation rates of the populations with ages of < 40 Myr and 100~400 Myr, respectively. The cold gas is most likely to be associated with the young stellar populations. Then the stellar feedback of the young populations could influence the warm gas. The age difference between the populations which show the correlations indicates the time delay of the stellar feedback.

• Asia-Pacific Journal of Business
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• v.14 no.4
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• pp.37-48
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• 2023

Purpose - This study aims to explore the influence of emotional discrepancies among investors on the cryptocurrency market. It focuses on how varying emotions affect market dynamics such as volatility and trading volume in the context of Bitcoin trading. Design/methodology/approach - This study involves analyzing data from Bitcointalk.org, consisting of 57,963 posts and 2,215,776 responses from November 22, 2009, to December 31, 2022. Tools used include the Linguistic Inquiry and Word Count (LIWC) software for classifying emotional content and the Python Pattern library for sentiment analysis. Findings - The results show that heterogeneous emotional feedback, whether positive or negative, significantly influences Bitcoin's intraday volatility, skewness, and trading volume. These findings are more pronounced when the underlying emotion in the feedback is amplified. Research implications or Originality - This study underscores the significance of emotional factors in financial decision-making, especially within the realm of social media. It suggests that investors and market strategists should consider the emotional landscape of online forums when making investment choices or formulating market strategies. The research also paves the way for future studies regarding the behavioral impact of emotions on the cryptocurrency market.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.780-786
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• 2015

Social media, such as Social Network Service include a lot of spontaneous opinions from customers, so recent companies collect and analyze information about customer feedback by using the system that analyzes Big Data on social media in order to efficiently operate businesses. However, it is difficult to analyze data collected from online sites accurately with existing morpheme analyzer because those data have spacing errors and spelling errors. In addition, many online sentences are short and do not include enough meanings which will be selected, so established meaning selection methods, such as mutual information, chi-square statistic are not able to practice Emotional Classification. In order to solve such problems, this paper suggests a module that can revise the meanings by using initial consonants/vowels and phase pattern dictionary and meaning selection method that uses priority of word class in a sentence. On the basis of word class extracted by morpheme analyzer, these new mechanisms would separate and analyze predicate and substantive, establish properties Database which is subordinate to relevant word class, and extract positive/negative emotions by using accumulated properties Database.

• The Journal of the Korea Contents Association
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• v.20 no.5
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• pp.37-45
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• 2020

The purpose of the study is to explore the perceptions or attitudes about utilizing the AWE(Automated Writing Evaluation), Grammarly in English writing. A total of 131 students who are in first grade and in beginner level participate in the study. As a research tool of the study, pre and post-surveys, pre and post-tests, and learning journals were collected and analyzed. The study was conducted for 15 weeks in the 2^nd semester of 2019. According to the results, the findings are as follows. First, the students in the study had difficulty with English grammar and found it useful to get English feedback in English writing. Next, the students showed positive attitudes toward the use of Grammarly. It was helpful for English learning and assignment performance and showed high usefulness. Finally, Grammarly's effect showed a statistically significant result between the pre and post-tests. Based on the results some suggestions are as follows. First, let the students take some time with the program to use to operate. Second, teachers have to make the students understand that AWE's feedback is not always correct. Lastly, it should be provided with teachers' feedback.

• Microbiology and Biotechnology Letters
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• v.16 no.3
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• pp.238-245
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• 1988

Studies were made on the regulation of chorismate mutase and prephenate dehydratase of a species of Intrasporangium, a phenylalanine producing Actinomycete isolated from soil. Two distinctly regulated species of chorismate mutase, designated CM I and CM IIwere resolved by DEAE Cellulose and DEAE Sephadex A 50 chromatography. The activity of CM II was inhibited by L-tyrosine, whereas that of CM I appeared to be unregulated. Single species of prephenate dehydyatase was also separated in the same purification steps. The activity of the enzyme was strongly feedback inhibited by L-phenylalanine, but by L-tyrosine or L-methionine it was rather slightly stimulated. Synthesis of chorismate mutase was not influenced by the presence of phenylalanine, tyrosine or tryptophan, whereas prephenate dehydratase was found to be subject to strong feedback repression by L-phenylalanine. The rate of repression was 94% at the concentration of 1mM L-phenylalanine but the repression was completely offset by the presence of 5mM tyrosine. The critical regulatory site of the phenylalanine terminal biopathway was, therefore, proved to be the second reaction which was catalyzed by the L-phenylalanine inhibitable and repressible prephenate dehydratase.

• International Journal of Control, Automation, and Systems
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• v.4 no.4
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• pp.414-427
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• 2006

This paper presents an adaptive feedback linearization control scheme for induction motors with simultaneous variation of rotor and stator resistances. Two typical modeling techniques, rotor flux model and stator flux model, have been developed and successfully applied to the controller design and adaptive observer design, respectively. By using stator fluxes as states, over-parametrization in adaptive control can be prevented and control strategy can be developed without the need of nonlinear transformation. It also decrease the relative degree for the flux modulus by one, thereby, yielding, a simple control algorithm. However, when this method is used for flux observer, it cannot guarantee the convergence of flux. Similarly, the rotor flux model may be appropriate for observers, but it is not so for adaptive controllers. In addition, if these two existing methods are merged into overall adaptive control system, it brings about structural complexies. In this paper, we did not use these two modeling methods, and opted for the airgap flux model which takes on only the positive aspects of the existing rotor flux model and stator flux model and prevents structural complexity from occuring. Through theoretical analysis by using Lyapunov's direct method, simulations, and actual experiments, it is shown that stator and rotor resistances converge to their actual values, flux is well estimated, and torque and flux are controlled independently with the measurements of rotor speed, stator currents, and stator voltages. These results were achieved under the persistent excitation condition, which is shown to hold in the simulation.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.6
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• pp.68-77
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• 2003

An improved negative capacitance circuit that cancels out input impedance of a front-end in a bioimpedance measurement and operates stably with a low gain margin has been proposed. Since the proposed circuit comprises wide-band operational amplifiers, selecting operational amplifiers is easy, while an operational amplifier of prefer bandwidth should be chosen to apply conventional circuit. Also, since gain margin can be controlled by a feedback resistor connected serially with a feedback capacitor, gain margin is tuneable with a potentiometer. The input impedance of the proposed circuit is two times larger than that of the conventional circuit and 40-times than that without a negative capacitance circuit. Furthermore, closed-loop phase response of the proposed circuit is better than that of the conventional circuit or without a negative capacitance circuit. Above all, for the proposed circuit, the frequency at which a gain peaking occurs is higher than the frequency at which the loop gain becomes a maximum. Thus, the proposed circuit is not affected by a gain peaking and can be operated with a very low gain margin.