• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.276-280
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• 2001

In this paper, an approach to the design of negative impedance stabilizing controllers for PWM DC/DC converters that are used in DC switching. power supplies with constant power loads is presented. The control approach is based on the feedback linearization technique. Because of the negative impedance destabilizing characteristics of constant power loads, classical linear control methods have stability limitations around the operating points. However, the proposed stabilizing technique improves large-signal stability and dynamic responses. The proposed controllers are simulated and their responses under different operations are studied. Stability of the control technique is also verified using the second theorem of Lyapunov.

• 한국경영정보학회:학술대회논문집
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• 2007.06a
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• pp.395-400
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• 2007

Previous studies present the mixed results on online reputation mechanism. In this study, we have found that an approach based on Bayesian statistics can explain most results of previous studies which are conflicting with each others. With this model, we explain why negative ratings have more significant marginal impacts on sellers' reputation than positive ones do. Furthermore, we even show why the feedbacks with a few negative ratings may increase the value of the item and final prices by confirming buyers' prior beliefs on the sellers' reputation much more than those without negative ratings. Also, we explain why there are not many negative ratings. Even though some studies suggest this because of generosity of users, our model shows that the reason is that the existence of FS itself prevents bad sellers from participating to the market as a signal itself. Even further, we show how this extreme tendency of positive ratings gets even stronger as markets evolve. Finally, to validate our analytical results, we examine the previous studies and see what factors effect the outcomes of their analyses.

• Journal of Korean society of Dental Hygiene
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• v.21 no.4
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• pp.481-489
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• 2021

Objectives: This study was conducted to understand the effect of learners' self-determination on class participation, focusing on the feedback type of educators. Methods: A survey was conducted from May 1 to May 31 2021 on dental hygiene students, and a total of 151 valid responses were analyzed. The questionnaire consisted of general characteristics, self-determination, class participation, and educator's feedback type. The analysis method used correlation analysis and hierarchical regression analysis. Results: In relation to self-determination, class participation, and feedback type of educators, self-determination was positive feedback (r=0.338, p<0.01), class participation was corrective feedback (r=0.418, p<0.01), and positive feedback was correction (r=0.742, p<0.01). As a result of the mediating effect of the educator's feedback type in the relationship between self-determination and class participation, it was found to be significant by partially mediating positive and corrective feedback. Conclusions: It was found that the right to self-determination influences class participation based on positive feedback and corrective feedback of educators. It relates to efforts to strengthen learners' self-determination and provide appropriate types of feedback from educators.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.11
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• pp.617-624
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• 2000

The negative weight can be ofter seen in Hopfield neural network, which is difficult to implement negative conductance in circuits. Usually, the inverted output of amplifier is used to avoid negative resistors for expressing the negative weights in hardware implementation. However, there is some difference between using negative resistor and the inverted output of amplifier for representing the negative weight. This difference is discussed in this paper.

• Biomolecules & Therapeutics
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• v.23 no.4
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• pp.320-326
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• 2015

The clinical benefits of oncogenic BRAF inhibitor therapies are limited by the emergence of drug resistance. In this study, we investigated the role of a negative regulator of the MAPK pathway, Spry2, in acquired resistance using BRAF inhibitor-resistant derivatives of the BRAF-V600E melanoma (A375P/Mdr). Real-time RT-PCR analysis indicated that the expression of Spry2 was higher in A375P cells harboring the BRAF V600E mutation compared with wild-type BRAF-bearing cells (SK-MEL-2) that are resistant to BRAF inhibitors. This result suggests the ability of BRAF V600E to evade feedback suppression in cell lines with BRAF V600E mutations despite high Spry2 expression. Most interestingly, Spry2 exhibited strongly reduced expression in A375P/Mdr cells with acquired resistance to BRAF inhibitors. Furthermore, the overexpression of Spry2 partially restored sensitivity to the BRAF inhibitor PLX4720 in two BRAF inhibitor-resistant cells, indicating a positive role for Spry2 in the growth inhibition induced by BRAF inhibitors. On the other hand, long-term treatment with PLX4720 induced pERK reactivation following BRAF inhibition in A375P cells, indicating that negative feedback including Spry2 may be bypassed in BRAF mutant melanoma cells. In addition, the siRNA-mediated knockdown of Raf-1 attenuated the rebound activation of ERK stimulated by PLX4720 in A375P cells, strongly suggesting the positive role of Raf-1 kinase in ERK activation in response to BRAF inhibition. Taken together, these data suggest that RAF signaling may be released from negative feedback inhibition through interacting with Spry2, leading to ERK rebound and, consequently, the induction of acquired resistance to BRAF inhibitors.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.2
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• pp.89-94
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• 2022

In this paper, a discrete-time loop filter(DLF) phase-locked loop with a Frequency Fluctuation Converting Circuit(FFCC) has been proposed. Discrete-time loop filter can improve spur characteristic by connecting the charge pump and voltage oscillator discretely unlike a conventional continuous-time loop filter. The proposed PLL is designed to operate stably by the internal negative feedback loop including the SSC acting as a negative feedback to the discrete-time loop filter of the external negative feedback loop. In addition, the phase noise is further improved by reducing the magnitude of the loop filter output voltage variation through the FFCC. Therefore, the magnitude of jitter has been reduced by 1/3 compared to the conventional structure. The proposed phase locked loop has been simulated with Hspice using the 1.8V 180nm CMOS process.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.6
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• pp.479-486
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• 2021

In this paper, an ultra small phase locked loop (PLL) with a single capacitor loop filter has been proposed by adding a signal sensing circuit (SSC). In order to extremely reduce the size of the PLL, the passive element loop filter, which occupies the largest area, is designed with a very small single capacitor (2pF). The proposed PLL is designed to operate stably by the output of the internal negative feedback loop including the SSC acting as a negative feedback to the output of the single capacitor loop filter of the external negative feedback loop. The SSC that detects the PLL output signal change reduces the excess phase shift of the PLL output frequency by adjusting the capacitance charge of the loop filter. Although the proposed structure has a capacitor that is 1/78 smaller than that of the existing structure, the jitter size differs by about 10%. The PLL is designed using a 1.8V 180nm CMOS process and the Spice simulation results show that it works stably.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1143-1153
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• 2010

In this paper, we propose an alternative method to increase the distortion cancellation bandwidth of an analog RF feedback power amplifier by using a negative group delay circuit(NGDC). A limited distortion cancellation bandwidth due to the group delay(GD) mismatch discouraged the use of feedback technique in spite of its powerful linearization performance. With the fabricated NGDC with positive phase slope over frequency, the feedback amplifier of the proposed topology experimentally achieved adjacent channel leakage ratio(ACLR) improvement of 15 dB over 50 MHz bandwidth at wideband code division multiple access(WCDMA) downlink band when tested with 2-carrier WCDMA signal. At an average output power of 28 dBm, ACLR of 25.1 dB is improved to obtain -53.2 dBc at 5 MHz offset.

• English Language & Literature Teaching
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• v.16 no.1
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• pp.171-188
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• 2009

The purpose of this study was to investigate the role of ongoing feedback from the professor in students' processes of learning and developing writing skills. Specifically, the researcher was concerned with how ongoing feedback affected students' attitudes towards writing because in EFL contexts, motivating students to write is a first step to engage them in a challenging journey of academic writing. 20 freshmen taking a writing course, "Paragraph & Essay Writing", at A university participated in this study and they were asked to complete the questionnaire at the end of the spring semester 2009. The results revealed that receiving ongoing feedback from the professor had a positive influence on affective domain, was helpful to develop learning strategies, and was valuable in learning outcomes. However, they also expressed negative opinions: feeling a burden, focusing on forms, and feeling confused. To reflect their opinions, the following four suggestions were made to create a more effective learning environment: promoting learner autonomy, facilitating individual writing conferences, giving balanced feedback in between form and content, and using judicious feedback through careful streaming.

• Korean System Dynamics Review
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• v.10 no.4
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• pp.39-51
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• 2009

In this paper, we constructed a cognitive map of President Lee of Korea on the policy vision of green growth. This cognitive map is characterized by a scarcity of feedback loops and a strong emphasis on the positive loops. These characteristics can be understood by the fact that the green growth policy is to overcome the limits to growth coming from negative feedback loops. As a conclusion, we proposed a negative feedback loop approach to the green growth policy vision, which might minimize the side effects of positive loops.