• Journal of the Korean Data and Information Science Society
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• 제21권5호
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• pp.967-972
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• 2010

We shall consider estimations of an exponetiated parameter of the exponentiated Pareto distribution with known scale and threshold parameters. A quotient distribution of two independent exponentiated Pareto random variables is obtained. We also derive the distribution of the ratio of two independent exponentiated Pareto random variables.

• Journal of Mechanical Science and Technology
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• 제15권11호
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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.

• 한국소음진동공학회논문집
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• 제22권4호
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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.

• Annals of Clinical Neurophysiology
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• 제21권2호
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• pp.87-93
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• 2019

Background: The standardized autonomic function test has become widely available. However, there are no reference data for this test for the Korean population. This study explored reference data for sudomotor and cardiovagal function tests for the Korean population. Methods: The sweat volume by quantitative sudomotor axon reflex test, heart-rate response to deep breathing (HRdb), expiration:inspiration (E:I) ratio, and Valsalva ratio (VR) were measured in 297 healthy Korean volunteers aged from 20 to 69 years. Multivariate regression analysis was performed to evaluate the effects of age, sex, and body mass index on these variables. The 2.5th, 5th, 10th, 90th, 95th, and 97.5th percentile values were obtained for each investigation. Results: The sweat volume was higher in males than in females. The HRdb and E:I ratio were negatively correlated with age, and were higher in males than in females. The VR was negatively correlated with age, but it was not correlated with sex. Conclusions: This study has provided data on the reference ranges for sudomotor and cardiovagal function tests in healthy Korean adults.

• Journal of Mechanical Science and Technology
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• 제16권7호
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• pp.873-881
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• 2002

In this paper, a on-line estimation method of the radial immersion angle using cutting force is presented. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the immersion angle is a function of the immersion angle and the ratio of radial to tangential cutting force. It is found that the ratio of radial to tangential cutting force is not affected by cutting conditions and axial rake angle, which implies that the ratio determined by one preliminary experiment can be used regardless of the cutting conditions for a given tool and workpiece material. Using the measured cutting force during machining and predetermined ratio, the radial immersion ratio is estimated in process. Various experimental results show that the proposed method works within 5% error range.

• Transactions on Electrical and Electronic Materials
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• 제13권2호
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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.

• 한국생산제조학회지
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• 제9권4호
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• pp.91-98
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• 2000

In this paper , presented is a method of on-line estimation of the radial immersion ratio and cutting force ratio using cutting force. When a tooth finishes sweeping, sudden drop of cutting forces occurs. These force drops are equal to the cutting forces that act on a single tooth at the swept angle of cut and can be obtained from cutting force signals in feed and crossfeed directions. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the swept angle of cut is a function of the swept angle of cut and the ratio of radial to tangential cutting force. In the research, it is found that the ratio of radial to tangential cutting force is not affected by cutting conditions and axial rake angle. Therefore, the ratio of radial to tangential cutting force determined by just one preliminary experiment can be used regardless of the cutting conditions. Using the measured cutting forces, the radial immersion ratio is estimated along with the cutting force ratio at that immersion angle. Various experiments show that the radial immersion ratio and instantaneous ratio of the radial to tangential direction cutting force can be estimated by the proposed method very well.

• 전자공학회논문지S
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• 제34S권2호
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• pp.94-103
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• 1997

The WCHF-FSJTC (wavelet circular harmonic function frequency selective joint transform correlator) using th wavelet transformed CHF as the reference image in FSJTC is proposed for rotation invariant pattern recognition. Since the wavelet transform has the property of feature extraction, the proposed system can have the better DC (discrimination cpability) and the higher SNR(signal to noise ratio) compared with the conventional CHF-CJTC(circular harmonic function conventional joint transform correlator). And since the structure of the proposed system is FSJTC which can eliminate auto-correlation and cross-correlation between input images, it can eliminate false alarm caused by the overlapping among correlation peaks. The used wavelet functio is the morlet function, which is proper for the reference image used in this paper. the optimal dialation parameter and oscillation frequency of the wavelet function are also achieved with varying the parameters of the wavelet function. The computer simulation shows that the proposed system has the best performance when the dilation parameter is 0.8 and the oscillation frequency is 0.48.

• 대한수학회지
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• 제45권2호
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• pp.559-573
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• 2008

In this paper, two classes of functions, involving a parameter and the classical Euler gamma function, and two functions, involving the classical Euler gamma function, are verified to be logarithmically completely monotonic in $(-\frac{1}{2},\infty)$ or $(0,\infty)$; some inequalities involving the classical Euler gamma function are deduced and compared with those originating from certain problems of traffic flow, due to J. Wendel and A. Laforgia, and relating to the well known Stirling's formula.

• 한국군사과학기술학회지
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• 제13권1호
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• pp.140-146
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• 2010

The multi-function radar can detect and track the low RCS targets. For this purpose the multi-function radar uses the pulse train waveform. because this waveform has high dynamic range and good SNR(Signal to Noise Ratio). But the spurious signals can also be detected by processing the pulse train waveform. Thus the multi-function radar signal processor must have the high SFDR(Spurious Free Dynamic Range). This paper describes the development of the multi-function radar signal processor having the high SFDR.