• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.11
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• pp.1959-1975
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• 2011

Adaptive Bit Loading (ABL) in Multiple-Input Multiple-Output Orthogonal Frequency-Division Multiplexing (MIMO-OFDM) is often used to achieve the desired Bit Error Rate (BER) performance in wireless systems. In this paper, we discuss some of the bit loading algorithms, compare them in terms of the BER performance, and present an effective and concise Adaptive Grouped Loading (AGL) algorithm. Furthermore, we propose a "weight factor" for loading algorithm to converge rapidly to the final solution for various data rate with variable Signal to Noise Ratio (SNR) gaps. In particular, we consider the bit loading in near optimal Singular Value Decomposition (SVD) based MIMO-OFDM system. While using SVD based system, the system requires perfect Channel State Information (CSI) of channel transfer function at the transmitter. This scenario of SVD based system is taken as an ideal case for the comparison of loading algorithms and to show the actual enhancement achievable by our AGL algorithm. Irrespective of the CSI requirement imposed by the mode of the system itself, ABL demands high level of feedback. Grouped Loading (GL) would reduce the feedback requirement depending upon the group size. However, this also leads to considerable degradation in BER performance. In our AGL algorithm, groups are formed with a number of consecutive sub-channels belonging to the same transmit antenna, with individual gains satisfying predefined criteria. Simulation results show that the proposed "weight factor" leads a loading algorithm to rapid convergence for various data rates with variable SNR gap values and AGL requires much lesser CSI compared to GL for the same BER performance.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.9
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• pp.62-66
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• 2016

This paper presents a MedRadio-band low power low noise amplifier for Medical Devices. A proposed MedRadio-band low power low noise amplifier adopts a current-reuse resistive feedback topology to increase overall gm and reduce power consumption. The gain of the LNA increases by the Q-factor of the additional series RLC input matching network, and its noise figure is minimized by the similar factor. Furthermore, it consumes low power because of low supply voltage and current reuse technique. By exploiting the $g_m$-booting and matching network property, the proposed MedRadio-band low noise amplifier achieves a noise figure of 0.85 dB, a voltage gain of 30 dB, and IIP3 of -7.9 dBm while consuming 0.18 mA from a 1 V supply voltage in $0.13{\mu}m$ CMOS technology.

• Journal of Families and Better Life
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• v.10 no.1 s.19
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• pp.15-25
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• 1992

This article introduces the conceptual framework of self-efficacy and reviewes recent research articles which are related to development of self-efficacy in children. Self-efficacy means personal judgement about one's capability to organize his behavior in a specific situation. Perceived efficacy can have diverse effects on behavior, thought patterns and affective arousal. People acquire their efficacy information from their performance accomplishments, vicarious experiences, verbal persuasion and their physiological states. In this paper, I argue that two factors, psychological and environmental factor, contribute to the development of children's self-efficacy. Specifically reward, attributional feedback, social comparision and goal setting are classified to psychological factor and home environment, school environment and social environment belong to environmental factor. Since not many studies have been done in this area, in this paper I also suggest some directions for future research.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.3
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• pp.270-276
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• 2018

This paper presents a low area 256-point pipelined FFT architecture, especially for IEEE 802.16a WiMAX systems. Radix-24 algorithm and single-path delay feedback (SDF) architecture are adopted in the design to reduce the complexity of twiddle factor multiplication. A new cascade canonical signed digit (CSD) complex multipliers are proposed for twiddle factor multiplication, which has lower area and less power consumption than conventional complex multipliers composed of 4 multipliers and 2 adders. Also, the proposed cascade CSD multipliers can remove look-up table for storing coefficient of twiddle factors. In hardware implementation with Cyclone 10LP FPGA, it is shown that the proposed FFT design method achieves about 62% reduction in gate count and 64% memory reduction compared with the previous schemes.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1030-1033
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• 2002

This paper, a new simple controller operates in continuous conduction mode (CCM) for Boost power factor collection converter is introduced. The duty ratios are obtained by comparisons of a sensed signal from inductor current and a negative ramp carrier waveform in each switching period. By using the proposed controller, input voltage sensing, error amplifier in the current feedback loop, and analog multiplier／divider are not required, then, the control circuit implementation is very simple. To verify the proposed controller, the circuit simulation for Boost power factor correction converter was applied. For the results, the input current waveform was shaped to be closely sinusoidal, implying low THD.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.281-286
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• 1998

This paper proposes a new single-stage, single-switch AC/DC converter based on the boost power factor correction (PFC) cell. The converter offers both high power factor and high efficiency. To reduce the dc voltage on the energy storage capacitor, the dc bus voltage feedback method was used. A 100W (5V/20A) prototype was built and tested to show the validity of the proposed converter.

• Asia-Pacific Journal of Business
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• v.6 no.2
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• pp.63-79
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• 2015

The purpose of this study is to examine the effects of transformational leadership on job satisfaction and to examine the effects of transactional leadership on job satisfaction. This study tried to verify the facial feedback hypothesis in causal relations of charisma, intellectual stimulation, individualized consideration, contingent reward, management by exception, job satisfaction. The self-administerd survey was undertaken against 380 respondents who soldier working in Daegu. A total of 375 responses were collected. Excluding missing data, 337 usable data were used for analysis. Results of this study are as follows. First, it is found that charisma factor is positively impact on job satisfaction. Second, it is found that individualized consideration factor is positively impact on job satisfaction. Third, it is found that contingent reward factor is positively impact on job satisfaction. Fourth, it is found that management by exception is positively impact on job satisfaction. The theoretical implication and practical implication for the army and government are discussed. The limitations are also mentioned.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.97-103
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• 2006

This paper described the design and performance evaluation of fiber optic gyro using digital closed-loop processing. For the feedback to null the gyro input rate, digital serrodyne modulation was employed, and for scale factor stabilization, the control circuits of modulation amplitude and optical power are implemented. Performance tests show that prototype fiber optic gyro has bias stability of 0.34 deg/hr, scale factor non-lineality of about 100ppm, and maximum measurement range of ${\pm}500$ deg/sec.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.113-122
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• 2011

This paper introduces and develops an efficient method for measuring power factor (PF) and its nature under nonlinear load current situations. The method is based on generating a pulse width modulated signal whose width correlates to the value of PF. This signal can then be employed as a feedback signal for controlling PF related power quantities in a system. This method has the advantages of its simple implementation, less computational complexity, and its allowable error of less than 4[%], which is justified by the computer simulation results.

• Hwankyungkyoyuk
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• v.8 no.1
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• pp.107-121
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• 1995

The goal of this study was to establish the evaluation method, which consist of the principle, factor, procedure and checklist, on environmental camp program and then to support staffs of environmental camp for decision-making to improve pre-program and develop new one. The main principles of the evaluation method established in this study were Hierarchical holism and Open inter-communication. First, hierarchical holism focused at the interaction among six factors, which were divided by 3 steps : 1) goal(and objectives) 2) learners and sites 3) activities, staffs and media. Second, open inter-communication could be defined a feedback process among all program participants : manager, staff, teacher, volunteer, learner and so on. The evaluation checklist had been developed of 10 comprehensive items and 30 factor-items at the preliminary step but some items were assessed some complex or duplicate in the result of 3 case studies. The suggested checklist was diminished to 5 comprehensive items and 25 factor-items. Several alternatives, which included specifing learners and objectives, developing site-oriented program and establishing the evaluation sheet were suggested for improving environmental camp program.