• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.10-12
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• 1996

AlGaAs/GaAs Heterojunotion Bipolar Transistors (HBTs) with various emitter areas were fabricated and the device size dependence on the current gain was examined. With the different emitter areas, the passivated devices having the same peripheral length were fabricated and measured. The measured base current density in the Gummel plots shows an ideality factor of nearly 2. It is found that as the emitter area becomes small, the base current density with the ideality factor of 2 increases linearly, and as the emitter perimeter/area ratio becomes large, the surface recombination current density component increases. The current gain performance in AlGaAs/GaAs HBTs is mainly determined by either the larger emitter area or the smaller ratio of the emitter perimeter to the emitter area. These results will be compared with experimental works for GaInP/GaAs HBTs

• International journal of advanced smart convergence
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• v.10 no.2
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• pp.175-186
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• 2021

We have studied the speed regulation of the permanent magnet synchronous motor (PMSM) servo system in this paper. To optimize the PMSM servo system's speed-control performance with disturbances, a non-linear speed-control technique using a back-propagation neural network (BP-NN) algorithm forthe controller design of the PMSM speed loop is introduced. To solve the slow convergence speed and easy to fall into the local minimum problem of BP-NN, we develope an improved BP-NN control algorithm by limiting the range of neural network outputs of the proportional coefficient Kp, integral coefficient Ki of the controller, and add adaptive gain factor β, that is the internal gain correction ratio. Compared with the conventional PI control method, our improved BP-NN control algorithm makes the settling time faster without static error, overshoot or oscillation. Simulation comparisons have been made for our improved BP-NN control method and the conventional PI control method to verify the proposed method's effectiveness.

• Journal of electromagnetic engineering and science
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• v.14 no.2
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• pp.47-53
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• 2014

This paper presents a high gain and high harmonic rejection low-noise amplifier (LNA) for software-defined radio receiver. This LNA exploits the high quality factor (Q) series resonance technique. High Q series resonance can amplify the in-band signal voltage and attenuate the out-band signals. This is achieved by a source impedance transformation. This technique does not consume power and can easily support multiband operation. The chip is fabricated in a $0.13-{\mu}m$ CMOS. It supports four bands (640, 710, 830, and 1,070MHz). The measured forward gain ($S_{21}$) is between 12.1 and 17.4 dB and the noise figure is between 2.7 and 3.3 dB. The IIP3 measures between -5.7 and -10.8 dBm, and the third harmonic rejection ratios are more than 30 dB. The LNA consumes 9.6 mW from a 1.2-V supply.

• Women's Health Nursing
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• v.9 no.3
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• pp.287-298
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• 2003

Purpose: To explain the concept of postpartum weight retention and to analyze factor effect on it. Method: A total of 20 studies related postpartum weight retention were selected in the year of 1988-2001 and analysis was done. Result: A demographic factor like parity, age, social and economic level and life style such as exercise, diet, breast feeding are influential factor on postpartum retention weight. But parts of them don't agree the same results. Meanwhile, in some studies, psychological factor like women's self esteem related to postpartum retention weight, body image change, depressing is found to be very related. As a result, postpartum overweight gain could be a bad factor of physical and mental health. In Korea, we have few studies related to them. Conclusion: It is required to do many-sided and deep studies about aspects of postpartum retention weight and the factor that effect on it. Postpartum retention weight should be approached by controling weight from the period of pregnancy. And it would rather be researched through individual approach considered women's various demographic, social-cultural and physical level than be required standardized level of weight gain.

• Asia pacific journal of information systems
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• v.26 no.1
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• pp.189-210
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• 2016

The current study attempts to expand our understanding of the determinants of energy-saving technology (EST) use by focusing on the individual aspects of environmental behaviors. This study integrates the hedonic, normative, and gain goals to explain the causal relationship between users and EST use. By adopting Goal-Framing Theory, this study proposed three individual goal frames in the environmental context: hedonic (perceived pleasurability), normative (social norms), and gain goals (legislative pressure and economic factor). Partial Least Square (PLS) was used to analyze the data from 104 respondents. Eight of the ten hypotheses were strongly supported. We found that social norms, perceived pleasurability, economic factor, and legislative pressure had positive and significant effects on attitude to EST use. Interestingly, we found that media influence did not have a severe effect on perceived pleasurability, and that the economic factor enforces mainly positive attitude to EST. Important theoretical and practical implications of these findings are discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1618-1623
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• 2008

In this paper, a new design method for IMC-PID that adds a phase scaling factor of system identifications to the standard IMC-PID controller as a control parameter is proposed. Based on analytically derived frequency properties such as gain and phase margins, this tuning rule is an optimal control method determining the optimum values of controlling factors to minimize the cost function, integral error criterion of the step response in time domain, in the constraints of design parameters to guarantee qualified frequency design specifications. The proposed controller improves existing single-parameter design methods of IMC-PID in the inflexibility problem to be able to consider various design specifications. Its effectiveness is examined by a simulation example, where a comparison of the performances obtained with the proposed tuning rule and with other common tuning rules is shown.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.338-341
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• 1994

This paper presents a Fuzzy-PID controller based on Fuzzy logic. Up to now PID controller has had the difficulty of obtaining the optimal gain, and Fuzzy controller has had the difficulty of determining scale factor affecting the performance of control. So that a Fuzzy-PID controller is presented here self tuning of the scale factor and optimal gain. The results of simulation show a good performance in comparison with Ziegler-Nichols controller, having the generality of determining the components of scale factor in Fuzzy rule.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.90-95
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• 2008

An SHGC(Solar Heat Gain Coefficient) is a determinant of total flux of solar radiation coming indoor and a critical factor in evaluating heating and cooling load. U-value represents heat loss while SHGC denominates heat gain. Recently, windows with high solar gain, mid solar gain or low solar gain are being produced with the development of Low-E coating technology. This study evaluated changes in energy consumption for heating and cooling according to changes in SHGC when using double-layered Low-E glass and triple layered Low-E glass in relation to double layered clear glass as base glass. An Office was chosen for the evaluation. For deriving optical properties of each window, WINDOW 5 by LBNL, an U.S. based company. and the results were analyzed to evaluate performance of heat and cooling energy on anannual basis using ESP-r, an energy interpretation program. Compared to the energy consumption of the double layered clear glass, the double layered Low-E glass with high solar gain consumed $69.5kWh/m^2,yr$, 9% more than the double layered clear glass in cooling energy. The one with mid solar gain consumed $63.1kWh/m^2,yr$, 1% less than the base glass while the one with low solar gain consumed $57.6kWh/m^2,yr$, 10% less than the base glass. When it comes to tripled layered glass, the ones with high solar showed 2% of increase respectively while the one with mid solar gain and low solar gain resulted 5% and 11% in decrease in energy consumption due to low acquisition of solar radiation. With respect to cooling energy. it was found that the lower the SHGC. the less energy consumption becomes.

• Korean Journal of Biological Psychiatry
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• v.18 no.4
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• pp.245-253
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• 2011

Objectives In the current study, we quantitatively estimated changes in appetite and eating behavior of bipolar disorder patients during the pharmacotherapy. We also investigated their contribution to the weight gain and their association with specific food-craving characteristics of the patients. Methods Subjects included forty-one bipolar disorder patients and fifty-six controls. Currently sustained natures of food craving were assessed using the General-Food Craving Questionnaire-Trait (G-FCQ-T) and changes in appetite and eating behavior were measured using the Drug-Related Eating Behavior Questionnaire (DR-EBQ). Results Compared to the control group, the patients' group showed significantly higher body mass index (t=2.028, p=0.045). The patients' group had significantly higher 'Preoccupation with food' factor score of G-FCQ-T (p=0.016) than that of the control group. Hierarchical multiple regression analysis showed that only 'preoccupation with food' factor independently predicted psychotropic medication-induced appetite change. Conclusions Appetite change while receiving psychotropic medication seems to be related to the weight-gain and associated with craving natures of 'preoccupation with food' in bipolar disorder. Appetite and/or eating behavioral changes measured by G-FCQ-T and DR-EBQ could be regarded as an important mediating factor in future studies exploring biological mechanisms of weight gain related with pharmacotherapy for bipolar disorder.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.271-272
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• 2006

This paper presented a new experimental gain tuning technique for a Multi-Axis Servo System. First, the investigation for proportional gain of velocity control loop by using a Dynamic Signal Analyzer (DSA) was performed. Using the FUNCTION characteristic of DSA based on the Bode plot, the Bode plot of open loop transfer function was obtained. In turn, the integral gain of a servo controller can be found out by using the Integration time constant extracted from the Bode plot of open loop transfer function. In the meanwhile, the positional gain of the servo controller has been obtained by using the Bode plot of the closed loop transfer function. We have also proposed the technique to find out an optimal parameter of a notch filter, which has a great influence on vibration reduction, by using the damping factor extracted from the Bode plot of closed loop transfer function.