• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.485-488
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• 2005

In this paper designed available pre-amplifier to Ultrabroadband power amplifier. Designed pre-amplifier used WJ company's AM1 which frequency characteristic and noise characteristic are superior. Designed to have superior VSWR characteristic and frequency characteristic covering broadband of 100MHz ${\sim}$ 3GHz using feedback.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1955-1957
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• 2003

This paper presents a novel defected ground structure (DGS) and its application to a microwave oscillator. The presented oscillator is designed so as to use the suggested defected ground structure as a feedback loop inducing a negative resistance as well as a frequency-selective circuit. Applying the feedback loop between the drain and the gate of a FET device produces precise phase conversion in the feedback loop. The equivalent circuit parameters of the DGS are extracted by using a three-dimensional EM calculations and simple circuit analysis method. The implemented 1.07 GHz oscillator exhibits 0 dBm output power with over 15% dc-to-RF power efficiency and -106 dBc/Hz phase noise at 100 kHz offset from carrier.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.141-143
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• 1994

The pulse width modulated class D power amplifier has the highest efficiency among various class amplifiers but the performances, such as bandwidth, distortion and stability are inferior to the conventional ones. In this paper, a new class D amplifier design is Presented employing dual feedback loops namely current and voltage feedback. The new design provides wide full-power bandwidth and stability at any load with high efficiency.

• Proceedings of the KSPS conference
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• 2003.05a
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• pp.105-108
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• 2003

The purpose of this paper was to evaluate the effect of auditory feedback on fundamental frequencies in prelingulally deaf children. Participants totaled three groups of sixty children: deaf children with cochlear implantation(CI), deaf children with hearing aids (HA), and children with normal hearing(NH). Fundamental frequencies were measured during sustained phonation of /a/. There were statistically significant differences of fundamental frequencies across the groups(p<.01). In post hoc analysis, HA and NH group showed statistically significant differences, but CI group didn't. In correlation analysis between Fo and the chronological age, there were significant negative tendencies in CI and NH group, but not in HA group. The characteristics of fundamental frequencies in CI group were found similar to NH group than HA group in this study. This could be understood as the effect of relatively sufficient auditory feedback after cochlear implantation.

• International Journal of Computer Science & Network Security
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• v.22 no.10
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• pp.43-50
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• 2022

The students' feedback is important to measure and improve teaching performance. Many teacher performance evaluation systems are based on responses to closed question, but the free text answers can contain useful information which had to be explored. In this paper we present a lexicon-based sentiment analysis to explore students' text feedback. The data was collected from a system for the evaluation of teachers by students developed and used in our university. The students comments are in Romanian language so we built a Romanian sentiment word lexicon. We used this to categorize the feeback text as positive, negative or neutral. In addition, we added a new polarity - indifferent - in order to categorize blank and "I don't answer" responses.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.4
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• pp.54-63
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• 1993

This paper presents the dynamic modeling and control methodology to arrest structural deflections of industrial robotic manipulators featuring elastic members retrofitted with surface bonded pizoelectric actuators and sensors. The cynamic modeling is accomplished by employing a variational theorem, prior to developing a finite element formulation. This finite element formulation accounts for both original robot member elements and also bonded piezoelectric material elements. The governing equation of motion is then modified by condensing the electric potential vectors and subsequently two different negative velocity feedback controllers are established; a constant-gain feedback controller and a constant- amplitude feedback controller. By adopting a Model P50 articulating industrial robot manufactured by Gerneral Electric Company, conputer simulations are underlaken in order to demonstrate superior performance characteristics to be accrued from this proposed methodology such as smaller deflections at the end-effector.

• Journal of Korean Elementary Science Education
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• v.24 no.2
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• pp.111-122
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• 2005

The goal of this study was to investigate the differences in the effect of feedback from different providers on elementary school students' science achievement and to examine the responses of the students regarding the feedback. Three 6th grade classes were chosen to be assigned as experimental group 1, experimental group 2, and control group, respectively. In experimental group 1, the teacher provided feedback with students concerning the formative evaluations which were conducted periodically. Experimental group 2 was the one in which students were organized into small groups to compose and exchange feedback with one another. No feedback was of offered to students in the control group. The results of the science achievement test indicated ,that the provision of feedback by the teacher resulted in more gains in student academic achievement. The interviews with students revealed that the learners made positive responses to the feedback provided by the teacher while they showed negative attitudes toward the feedback exchange among students. There were also differences in student responses to feedback between high and low achievers in science. Implications for science lessons and science education research were presented and discussed.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.638-648
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• 2003

An active capacitance circuit is analyzed in depth and its application to active RF BPF with low noise figure is discussed. The characteristics of the active capacitance circuit made of FET[1] exhibits negative resistance and conventional capacitance, which is easily controlled. However, it is difficult to make the negative resistance adequate in the designated frequency range due to the lack of detailed analysis, which could make an active circuit unstable as the frequency is going higher or lower. In this paper, we analyzed the negative resistance characteristics of active capacitance circuits and also presented the method that the flatness of passband can be controlled. Finally we have designed a 4-stage active BPE, which results in bandwidth of 100 MHz, 0,04 dB insertion loss, 0.2 dB ripple, and noise figure of 2.4 dB at 1.75 GHz band.

• International Journal of Computer Science & Network Security
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• v.23 no.3
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• pp.101-109
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• 2023

This paper discusses the use of sentiment analysis and text summarization techniques to extract valuable information from the large volume of user-generated content such as reviews, comments, and feedback on online platforms and social media. The paper highlights the effectiveness of sentiment analysis in identifying positive and negative reviews and the importance of summarizing such text to facilitate comprehension and convey essential findings to readers. The proposed work focuses on summarizing all positive and negative reviews to enhance product quality, and the performance of the generated summaries is measured using ROUGE scores. The results show promising outcomes for the developed methods in summarizing user-generated content.

• Journal of Information Technology Services
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• v.23 no.2
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• pp.83-97
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• 2024

This study was conducted to examine the effect of institutional mechanisms on customers' trust and continuous purchase intention in open market platforms, The research frame was expanded by setting institutional situations into positive and negative areas in order to examine the relationship between institutional mechanisms and trust in multiple dimensions. The results of this study confirmed that the feedback system, dispute resolution, and intermediary trust factors affect trust in positive areas, and dispute resolution, information security, and intermediary trust affect buyer trust in negative areas. For the relationship between trust and repurchase intention, it was confirmed that if the institutional situation is positive, trust leads to repurchase intention, and in negative areas, trust does not lead to repurchase intention. The results of this study show that institutional mechanisms are a key factor in building trust in online platforms according to institutional circumstances and play a role in offsetting trust in platforms in negative areas.