• Communications for Statistical Applications and Methods
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• v.21 no.2
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• pp.183-191
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• 2014

We define a multivariate Cauchy distribution using a probability density function; subsequently, a Ferguson's definition of a multivariate Cauchy distribution can be viewed as a characterization theorem using the characteristic function approach. To clarify this characterization theorem, we construct two dependent Cauchy random variables, but their sum is not Cauchy distributed. In doing so the proofs depend on the characteristic function, but we use the cumulative distribution function to obtain the exact density of their sum. The derivation methods are relatively straightforward and appropriate for graduate level statistics theory courses.

• Journal of KSNVE
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• v.9 no.6
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• pp.1193-1199
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• 1999

This paper deals with the free vibrations of circular curved beams with thin-walled cross-section. The differential equation for the coupled flexural-torsional vibrations of such beams with warping is solved numerically to obtain natural frequencies and mode shapes. The Runge-Kutta and determinant search methods, respectively, are used to solve the governing differential equation and to compute the eigenvalues. The lowest three natural frequencies and corresponding mode shapes are calculated for the thin-walled horizontally curved beams with hinged-hinged, hinged-clamped, and clamped-clamped end constraints. A wide range of opening angle of beam, warping parameter, and two different values of slenderness ratios are considered. Numerical results are compared with existing exact and numerical solutions by other methods.

• Communications for Statistical Applications and Methods
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• v.25 no.5
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• pp.559-568
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• 2018

Gene classification can involve complex order-restricted inference. Examining gene expression pattern across groups with order-restriction makes standard statistical inference ineffective and thus, requires different methods. For this problem, Roy's union-intersection principle has some merit. The M-estimator adjusting for outlier arrays in a microarray study produces a robust test statistic with distribution-insensitive clustering of genes. The M-estimator in conjunction with a union-intersection principle provides a nonstandard robust procedure. By exact permutation distribution theory, a conditionally distribution-free test based on the proposed test statistic generates corresponding p-values in a small sample size setup. We apply a false discovery rate (FDR) as a multiple testing procedure to p-values in simulated data and real microarray data. FDR procedure for proposed test statistics controls the FDR at all levels of ${\alpha}$ and ${\pi}_0$ (the proportion of true null); however, the FDR procedure for test statistics based upon normal theory (ANOVA) fails to control FDR.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.404-406
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• 2014

The NDIF method is developed for eigenvalue analysis of arbitrarily shaped two-dimensional acoustic cavity with a mixed boundary, which consists of rigid-wall and open boundaries. The NDIF method, which was developed by the author in 2000, has the feature that it yields highly accurate eigenvalues compared with other analytical methods or numerical methods (FEM and BEM). The validity of the proposed method is shown in a case study, which indicate that eigenvalues obtained by the proposed method are more accurate compared to the exact method or FEM(ANSYS).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.550-554
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• 2014

Regarding thin films in MEMS/NEMS structures, the exact evaluation of mechanical properties is very essential to enhance the reliability of their design and manufacturing. However, such methods as a tensile test and a resonance test, general methods to measure elastic moduli, cannot be applied to thin films since its thickness is so small. This work concerns guided wave based elastic modulus measurement method. To this end, guided wave excitation and detection system using a pulsed laser and a laser interferometry has been established. Also an elastic modulus extraction algorithm from the measured guided wave signal was developed. Finally, it was applied to actual thin film structures such as Ni-Si and Al-Si multilayers. From experimental results, we confirm that the proposed method has considerable feasibility to measure elastic properties of thin films.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.46-50
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• 2002

In other to evaluate the static and dynamic stiffness of machine tool structure, the accuracy and error from experimental methods are studied in this paper. The F.E.M., impulse tests and exciter tests are performed for the general simple structure whose exact solution can be obtained. So that the parameter and dynamic compliance can be got. From the result, the variation of natural frequency can be verified from the static preload. Further more the relationship of identify and difference for compliance and direction is presented in the exciting direction and measurement direction.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.203-211
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• 1999

Threr are several methods in protecting the building structures from dynamic loads such as an earthquake and a wind. Among them applying a control force to the building structure is one of the methods to decrease the vibration. The most important and difficult problem in the active control is to obtain the mathematical model of the building structure with a controller. the effective active controller can be designed from the exact model of the system In this paper the three story test building with an active mass driver is identified experimentally. the system matrices corresponding to the experimental building are found and verified with the experimentally-obtained transfer functions and responses efficiently.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.704-708
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• 2002

Production scheduling has been one of the most critical issues in a manufacturing environment Job-shop scheduling problems(JSP) are well know from the standpoint of production planning and operations control in this research scheduling against due date is a measure of performance and the objective is minimizing total weighted tardiness This paper presents an idea of decomposition of the problem and shows robustmess of the schedule under various disturbances along with exact and approximation methods. The proposed method can indeed handle shop disturbances more effectively when compared with traditional and dynamic scheduling methods.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.603-610
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• 2008

In this paper, analytical methods for calculating the average probability of bit error of direct sequence pulse amplitude modulation ultra wideband (DS-PAM UWB) system and time hopping pulse position modulation ultra wideband (TH-PPM UWB) system are given. For the multi-user DS-PAM UWB system, the bipolar pulse amplitude modulation is used in order to achieve better performance. As we know, more attention is paid to the TH-PPM UWB systems recently. In this paper. we first introduce the accurate BER calculation methods of the multi-user DS-PAM UWB and TH-PPM UWB systems and then give the performance analysis over the ideal AWGN channel and a correlation receiver. Furthermore, we also introduce their applications in image transmission and data transmission and give the simulation results. The analytical method yields simple and exact formulas relating the performance to the system parameters.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.16 no.3
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• pp.300-306
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• 2009

Purpose: This study was done to investigate differences between lavender abdominal massage and inhalation on dysmenorrhea, menstrual pain, anxiety, and depression. Methods: This study used a non equivalent quasi-experimental design. Lavender essential oil and almond oil were used in massage and a lavender necklace and artificial perfume necklace in inhalation for female college students. Frequencies, percentages, Chi-square, Fisher's exact test and t-test with the SPSS/WIN 12.0 program were used to analyze the data. Results: Dysmenorrhea was significantly higher inhalation for placebo treatment compared to lavender inhalation (p< .001). There was not significant difference between lavender abdominal massage and inhalation. Conclusion: Lavender abdominal massage and inhalation could be effective methods to reduce dysmenorrhea. However, before lavender abdominal massage and inhalation can be considered as intervention, it is more needed to study of menstrual pain, anxiety and depression.