• The Pure and Applied Mathematics
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• v.2 no.2
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• pp.141-148
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• 1995

In this paper we shall consider function p(z) analytic in the open unit circle D and the solutions y(z) of the differential equation y"(Z) ＋ p(z)y(z) = 0. (1.1) The ratio f(z) = u(z)/v(z) of any two independent solutions u(z) and v(z) of (1.1) will be function f(z), meromorphic in D with only simple poles, and such that f'(z) (equation omitted) 0. We shall say that a meromorphic function which satisfies these two condition belongs to the restricted class.(omitted)

• Computational Structural Engineering
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• v.8 no.4
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• pp.159-171
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• 1995

The parameters describing a complete hysteresis loop include pinch force, drift offset, effective stiffness, unloading and reloading trangential stiffness. Analytical equations proposed to quantify the nonlinear, inelastic behavior of reinforced shear walls can be used to predict these parameters as a function of axial load and drift ratio. For example, drift offset, effective stiffness, and first and second unloading and reloading tangential stiffness are calculated using equations obtained from test data for a desired drift ratio or ductility level. Pinch force can also be estimated for a given drift ratio and axial load. The effective virgin stiffness at the first yield and its post yield reduction can be estimated. The load deflection response of flexural reinforced concrete shear walls can now be estimated based on the effective wall stiffness that is a function of axial force and drift ratio.

• Restorative Dentistry and Endodontics
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• v.40 no.2
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• pp.113-122
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• 2015

Objectives: The aim of this paper was evaluating the ratios of electrical impedance measurements reported in previous studies through a correlation analysis in order to explicit it as the contributing factor to the accuracy of electronic apex locator (EAL). Materials and Methods: The literature regarding electrical property measurements of EALs was screened using Medline and Embase. All data acquired were plotted to identify correlations between impedance and log-scaled frequency. The accuracy of the impedance ratio method used to detect the apical constriction (APC) in most EALs was evaluated using linear ramp function fitting. Changes of impedance ratios for various frequencies were evaluated for a variety of file positions. Results: Among the ten papers selected in the search process, the first-order equations between log-scaled frequency and impedance were in the negative direction. When the model for the ratios was assumed to be a linear ramp function, the ratio values decreased if the file went deeper and the average ratio values of the left and right horizontal zones were significantly different in 8 out of 9 studies. The APC was located within the interval of linear relation between the left and right horizontal zones of the linear ramp model. Conclusions: Using the ratio method, the APC was located within a linear interval. Therefore, using the impedance ratio between electrical impedance measurements at different frequencies was a robust method for detection of the APC.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.4
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• pp.383-392
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• 2012

This paper reports the active vibration control of plates using a positive position feedback(PPF) controller with moment pair actuators. The equations of motion of the plates under a force and moment pairs are derived and the equations of PPF controllers are formulated. The numerical active control system is then achieved. The effect of the parameters - gain and damping ratio - of the PPF controllers on the open loop transfer function was investigated mainly in terms of the system stability. Increasing the gain of the PPF controller tuned at a mode, the magnitude of the open loop transfer function is increased at all frequencies without changing the phase behavior. The increase of the damping ratio of the PPF controller leads to decrease the magnitude of the open loop transfer function and to modify its phase characteristics, ie, system stability. Based on the behavior of the gain and the damping ratio of the controller, PPF controller for reduction of the plate vibration can be achieved. Two PPF controllers are designed with their connection in parallel to control the two modes simultaneously. Each PPF controller is tuned at the $1^{st}$ and $2^{nd}$ modes, respectively. Their parameters were determined to remain the system to be stable based on the results of the parametric study. A significant reduction in vibration at the tuned modes can be obtained.

• Journal of Mechanical Science and Technology
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• v.15 no.11
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• pp.1541-1547
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• 2001

The non-dimensional fin length for optimum heat loss from a thermally asymmetric rectangular fin is represented as a function of the ratio of the bottom surface Biot number to the top surface Biot number, fin tip surface Biot number and the non-dimensional fin width. Optimum heat loss is taken as 98% of the maximum heat loss. For this analysis, three dimensional separation of variables method is used. Also, the relation between the ratio of the bottom surface Biot number to the top surface Biot number and the ratio of the right surface Biot number to the left surface Biot number is presented.

• Korean Institute of Interior Design Journal
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• v.23 no.6
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• pp.212-220
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• 2014

Entrance floor in hospital has became important space for medical service in holistic perspective and image enhancement. However, basically a discussion of the qualitative properties and the role of public space is paucity in change of public spaces paradigm. In accordance with this problem, this study consider the change of paradigm in public space based on earlier studies and create classification criterion of space. According to the criterion, G/D ratio and the qualitative spatial area ratio of 26 general hospitals which were planned over 500 beds are analyzed by case study method. The conclusion of this study is as follows. 1) The space according to the medical function is variable element. So the public space should be planned from function-subordinate space to self-reliance space in the future. 2) There is no correlation between the high G/D ratio and the high ratio of qualitative spacial area. In other word It's hard to say that the public space which G/D ratio is high is qualitative space. 3) Since 2000, various types in accordance with the circulation system is applied to public space. And ratio of qualitative spacial area is relatively high in the street type and the concourse type. 4) The qualitative spatial area ratio of stay space is higher than passage's one.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.231-234
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• 2004

Ratio that robot occupies is low level worldwide fairly in suspension wire, electricity electron and neutralization learning industry and domestic industry of this is staring in average love. Can speak that grafting of robotic machine and neutralization learning industry is high in terms of side of creation of the added value or progress of technology rightly hereupon. This research raises or designed multi-function handling robot that can make welding, assembly conveniently catching large size work water

• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.98-101
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• 2012

I studied the stability of organic photovoltaic cells in terms of P3HT:PCBM-71 blend ratio as a function of storage time. I obtained the best cell performance by optimizing the blend ratio of electron donor and electron acceptor within the active layer. In this study, I found that the more the P3HT:PCBM ratio increases within the active layer, the more the cell efficiency decreases as the storage time increases. As a result, the best optimized blend ratio was the 1:0.6 ratio of P3HT:PCBM-71, and cell efficiency of the device with the 1:0.6 blend ratio was 4.49%. The device with the best cell efficiency showed good stability.

• Journal of Ceramic Processing Research
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• v.23 no.6
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• pp.766-769
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• 2022

A Battery capacitor was prepared by controlling the mixing ratio of positive materials of the positive electrode to optimize cellproperties. The positive electrode was made by mixing two types of LiNi0.6Mn0.6Co0.2O2 (NMC 622) and LiCoO2 (LCO), andthe electrode was fabricated by changing the ratio of the two positive materials. Increasing of the content of LCO, decreasedthe capacity, and the retention of discharge capacity as a function of current rates did not change remarkably with anincreasing of the content LCO on the mixing ratio of positive materials. The life characteristics showed the highest capacityretention rate compared to the initial period under the condition that the ratio of NCM and LCO was 66 to 20. These resultsclearly indicate that mixing ratio of positive materials affects the electrochemical performances of battery capacitor.

• Proceedings of the Korean Society for Quality Management Conference
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• 1998.11a
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• pp.610-621
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• 1998

In parameter design introduced by Taguchi, we analyze a signal-to-noise(SN) ratio. The SN ratio is a function of the expected loss due to the variation of quality characteristic. In this paper, an easy way for developing SN ratios is presented, which can be used to several quality characteristics simultaneously in parameter design. To develop such multivariate SN ratios, the transformation method of the expected loss and combining techniques are employed. And the analysis of real empirical data for an application of the proposed method is also presented.