• The Journal of the Acoustical Society of Korea
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• v.7 no.2
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• pp.65-73
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• 1988

In this paper, V(z) curve has been analyzed theoretically and compared with the experimental result, and the relation between the V(z) curve and the material characteristic has been studied. Angular spectrum and ray optics theory have been used for theoretical analysis and the acoustic microscope operating at a center frequency of 3 MHz has been used for experiment. In experiment, it has been shown that each material has a V(z) curve of a unique form and the interval of dips appearing in the V(z) curves have been used to determine the Rayleigh wave velocity.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.3
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• pp.263-267
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• 2005

Building classifiers for financial real-world classification problems is often plagued by severely overlapping and highly skewed class distribution. New performance measures such as receiver operating characteristic (ROC) curve and area under ROC curve (AUC) have been recently introduced in evaluating and building classifiers for those kind of problems. They are, however, in-effective to evaluation of classifier's discrimination performance in a particular class of the classification problems that interests lie in only a local operating range of the classifier, In this paper, a new method is proposed that enables us to directly improve classifier's discrimination performance at a desired local operating range by defining and optimizing a partial area under ROC curve or domain-specific curve, which is difficult to achieve with conventional classification accuracy based learning methods. The effectiveness of the proposed approach is demonstrated in terms of fraud detection capability in a real-world fraud detection problem compared with the MSE-based approach.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.5 no.6
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• pp.69-78
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• 1982

Traditional CVP (Cost-Volume-Profit) analysis employs linear cost and revenue functions within some specified time period and range of operations. Therefore CVP analysis is assumption of constant labor productivity. The use of linear cost functions implicity assumes, among other things, that firm's labor force is either a homogenous group or a collection homogenous subgroups in a constant mix, and that total production changes in a linear fashion through appropriate increase or decrease of seemingly interchangeable labor unit. But productivity rates in many firms are known to change with additional manufacturing experience in employee skill. Learning curve is intended to subsume the effects of all these resources of productivity. This learning phenomenon is quantifiable in the form of a learning curve, or manufacturing progress function. The purpose d this study is to show how alternative assumptions regarding a firm's labor force may be utilize by integrating conventional CVP analysis with learning curve theory, Explicit consideration of the effect of learning should substantially enrich CVP analysis and improve its use as a tool for planning and control of industry.

• Journal of International Academy of Physical Therapy Research
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• v.9 no.2
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• pp.1513-1516
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• 2018

The purpose of this study was to identify the effect of upper thoracic mobilization on cervical alignment in stroke patients with forward head posture. The subject's of this study were two stroke patients with forward head posture and a cervical curve angle (four-line Cobb's method; FLCM) less than $40^{\circ}$. The intervention, central posterior-anterior (PA) mobilization, was applied to the T1-T4 vertebrae (upper thoracic spine) following the Maitland concept. This mobilization was applied three times per week for four weeks. In the results, the cervical curve angle (FLCM) increased for both subject 1 and 2. However, Jochumsen method score was decreased in subject 1, while it was increased in subject 2. These results demonstrate that upper thoracic mobilization had the positive effect on the cervical curve angle but not on Jochumsen method score. These findings suggest that PA mobilization on the upper thoracic spine could correct cervical curve angle measured by FLMC in stroke patients with FHP.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.1
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• pp.17-28
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• 2019

Jominy hardenability curves of low alloy steel containing less than 5 wt.% of alloying elements in total were calculated by applying Scheil's rule of additivity to pre-calculated isothermal transformation curve. Isothermal transformation curve for each phase in steel was approximated as a simple mathematical equation by using Kirkaldy's approach and all coefficients in the equation were estimated from experimental temperature-time-transformation (TTT) and/or continuous cooling transformation (CCT) data in the literature. Then jominy test with simple boundary conditions was performed in computer by applying the finite difference scheme. The resultant cooling curves at each location along a longitudinal direction of Jominy bar were applied to calculate phase fractions as well as mechanical properties such as micro Vickers hardness. The simulated results were compared with experimental CCT data and Jominy curves in the literature.

• International Journal of Computer Science & Network Security
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• v.21 no.3
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• pp.60-70
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• 2021

In this paper we study the problem of implementation of security issues of blue tooth, especially secure simple pairing, with the help of an efficient four user authenticated key (4UAK) for an elliptic curve cryptography (ECC). This paper also deals with the design, implement and performance evaluation of secure simple pairing (SSP) using an elliptic curve cryptography, such as Diffie Hellman protocol when four users are involved. Here, we also compute the best, worst and average case step counts (time complexities). This work puts forth an efficient way of providing security in blue tooth. The time complexity of O(n⁴) is achieved using Rabin Miller Primality methodology. The method also reduces the calculation price and light communication loads.

• Bulletin of the Korean Mathematical Society
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• v.39 no.1
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• pp.89-95
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• 2002

In this paper, we obtain an integral formula relating the measure of great spheres $S^{n-2}$ and arc length of a curve on the unit sphere $S^{n-1$ As an application of the formula, we develop a geometric inequality for a spherical curve and prone generalized version of Fenchel＇s theorem in $S^n$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.899-900
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• 2009

• Journal of Multimedia Information System
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• v.5 no.4
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• pp.235-244
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• 2018

Potential maximum soil moisture retention (S) is a dominant parameter in the Soil Conservation Service (SCS; now called the USDA Natural Resources Conservation Service (NRCS)) runoff Curve Number (CN) method commonly used in hydrologic modeling for event-based flood forecasting (SCS, 1985). Physically, S represents the depth [L] soil could store water through infiltration. The depth of soil moisture retention will vary depending on infiltration from previous rainfall events; an adjustment is usually made using a factor for Antecedent Moisture Conditions (AMCs). Application of the method for continuous simulation of multiple storms has typically involved updating the AMC and S. However, these studies have focused on a time step where S is allowed to vary at daily or longer time scales. While useful for hydrologic events that span multiple days, this temporal resolution is too coarse for short-term applications such as flash flood events. In this study, an approach for deriving a time-variable potential maximum soil moisture retention curve (S-curve) at hourly time-scales is presented. The methodology is applied to the Napa River basin, California. Rainfall events from 2011 to 2012 are used for estimating the event-based S. As a result, we derive an S-curve which is classified into three sections depending on the recovery rate of S for soil moisture conditions ranging from 1) dry, 2) transitional from dry to wet, and 3) wet. The first section is described as gradually increasing recovering S (0.97 mm/hr or 23.28 mm/day), the second section is described as steeply recovering S (2.11 mm/hr or 50.64 mm/day) and the third section is described as gradually decreasing recovery (0.34 mm/hr or 8.16 mm/day). Using the S-curve, we can estimate the hourly change of soil moisture content according to the time duration after rainfall cessation, which is then used to estimate direct runoff for a continuous simulation for flood forecasting.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.4
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• pp.308-313
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• 2012

Robust tuning rules of the motion profile are proposed to minimize the residual vibration. For asymmetric S-curve profile, tuning rules are analytically formulated using Laplace-domain approach. When the system modeling is known exactly, by placing a single zero of the motion profile on the pole of the system, the residual vibration can be perfectly eliminated under undamped system. However, if there are some amounts of the modeling errors, the residual vibration significantly increases. To track this issue, the robust tuning rules against modeling error are discussed. One of the proposed robust tuning rules is placing the multiple zeros of the motion profile on the pole of the system, and the other is placing the zeros of the motion profile around the pole of the system. Thanks to the proposed robust tuning rules, motion profile becomes more robust to modeling errors while minimizing the residual vibration. By simulation, the effectiveness of the proposed robust tuning rules is verified.