• Journal of the Korean Institute of Intelligent Systems
• /
• v.11 no.4
• /
• pp.340-346
• /
• 2001

This paper proposes a new design method for the GBAM: (general bidirectional associative memory) model. Based on theoretical investigations on the GBAM: model, it is shown that the design of the GBAM:-based bidirectional associative memeories can be formulated as optimization problems called GEVPs (generalized eigenvalue problems). Since the GEVPs arising in the procedure can be efficiently solved within a given tolerance by the recently developed interior point methods, the design procedure established in this paper is very useful in practice. The applicability of the proposed design procedure is demonstrated by simple design examples considered in related studies.

• Journal of Mechanical Science and Technology
• /
• v.20 no.12
• /
• pp.2189-2196
• /
• 2006

The present work is concerned with the development of a procedure for adaptive computations of shear localization problems. The maximum jump of equivalent strain rates across element boundaries is proposed as a simple error indicator based on interpolation errors, and successfully implemented in the adaptive mesh refinement scheme. The time step is controlled by using a parameter related to the Lipschitz constant, and state variables in target elements for refinements are transferred by $L_2$-projection. Consistent tangent moduli with a proper updating scheme for state variables are used to improve the numerical stability in the formation of shear bands. It is observed that the present adaptive mesh refinement procedure shows an excellent performance in the simulation of shear localization problems.

• Journal of Korean Neurosurgical Society
• /
• v.53 no.4
• /
• pp.249-251
• /
• 2013

Pneumocephalus is a condition characterized by the presence of air in the cranium, and it is mainly caused by trauma or a neurosurgical procedure. In the absence of head trauma or a neurosurgical procedure, meningitis is an extremely rare cause of pneumocephalus. Here, the authors present a rare case of spontaneous pneumocephalus caused by pneumococcal meningitis, in which simple lateral radiography and computed tomography (CT) findings of the skull suggested the diagnosis. Cerebrospinal fluid analysis showed bacterial meningitis which later revealed streptococcus pneumonia. The patient was treated with antibiotics and responded remarkably well. Repeat CT performed after 2 weeks of treatment showed complete resolution of the intracranial gas. Here, the authors report an unusual case of a pneumocephalus caused by meningitis in the absence of head trauma or a neurosurgical procedure.

• Journal of Korean Neurosurgical Society
• /
• v.63 no.3
• /
• pp.373-379
• /
• 2020

Carotid endarterectomy (CEA) is the main procedure in carotid surgery, as well as the most frequent vascular procedure. Two techniques of CEA are available : eversion and conventional plus patch angioplasty. Eversion CEA is anatomic procedure that reduces ischemic and total operative time. Simultaneous correction of the joined carotid kinking and coiling is possible, easy and safe, while the usage of patch is excluded. Thanks to oblique shape of anastomosis, eversion CEA is associated with low risk of long-term restenosis. The false anastomotic aneurysms occurrence is very rare, almost impossible after eversion CEA. However, the usage of carotid shunt during eversion CEA is not always simple, while proximal or distal extension of the carotid plaque can make eversion CEA more difficult and risky. Eversion CEA should be the first choice in carotid surgery. Conventional CEA is indicated in cases when carotid plaque is extended more than usual, as well as, if the usage of carotid shunt is necessary.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1995.04a
• /
• pp.476-486
• /
• 1995

In this paper, an attempt has been made to revise Raafat' s(1985) results on an inventory model for decaying raw materials and the finished product at a constant rate which was based on Goyal's integrated inventory model for a single product system. This paper is concerned with scheduling the frequencies of order quantity of several different raw materials on a production inventory model. The purpose of this paper is to present a simple method of deciding the frequencies of order quantity of raw materials, in the sense of minimizing the average total cost of the system. We describe on iterative procedure for directly determining near optimal frequencies of order quantity for the raw materials and the associated fundamental cycle time which can be used for constructing the production duration of the finished product. In cases where feasible schedules cannot be constructed using the values from the iterative procedure, the procedure provides a basis for changing the order quantity frequencies and the fundamental cycle time to obtain feasible schedules. An example is given to illustrate the derived results.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2006.11a
• /
• pp.165-168
• /
• 2006

Exponential smoothing methods do not adapt well to unexpected changes in underlying process. Over the past few decades a number of adaptive smoothing models have been proposed which allow for the continuous adjustment of the smoothing constant value in order to provide a much earlier detection of unexpected changes. However, most of previous studies presented ad hoc procedure of adaptive forecasting without any theoretical background. In this paper, we propose a detection-adaptation procedure applied to simple and Holt's linear method. We derive level and slope change detection statistics based on Bayesian statistical theory and present distribution of the statistics by simulation method. The proposed procedure is compared with previous adaptive forecasting models using simulated data and economic time series data.

• Communications for Statistical Applications and Methods
• /
• v.8 no.3
• /
• pp.719-729
• /
• 2001

Overlap Maximization is a sampling technique to reduce survey costs and costs associated with the survey. It was first studied by Keyfitz(1951). Ernst(1998) presented a remarkable procedure for maximizing the overlap when the sampling units can be selected for two identical stratified designs simultaneously, But the approach involves mimicking the behaviour of nonlinear function by linear function and so it is less direct, even though the stratification problem for the overlap corresponds directly to the linear programming problem. furthermore, it uses the controlled selection algorithm that repeatedly needs zero-restricted controlled roundings, which are solutions of capacitated transportation problems. In this paper we suggest a comparatively simple procedure to use linear programming in order to maximize the overlap. We show how this procedure can be implemented practically.

• Journal of KSNVE
• /
• v.10 no.4
• /
• pp.679-685
• /
• 2000

A procedure is presented for calculating the magnitude and shape of impact pulses in a vibro-impact system when an arbitrary input force is applied to a point in the system. The procedure utilizes the condition that the displacements of two contacting point in the primary and secondary system are the same during a contacting period. The displacements of those points are calculated numerically through the convolution integral which involve the impulse response functions and applied forces. The validity of the calculation procedure is demonstrated by using it to calculated the impact forces of a simple system where a theoretical solution is known and also of systems for which other researchers have published results. The agreement between the results derived by the numerical method and the theoretical and also some published results is good.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2002.09a
• /
• pp.258-265
• /
• 2002

Most structures are expected deform nonlinear and inelastic behavior when subjected to strong ground motion. Nonlinear time history analysis(NTHA) is the most rigorous procedure to compute seismic performance in the various inelastic analysis methods. But nonlinear analysis procedures necessitate more reliable and practical tools for predicting seismic behavior of structures. Some building codes propose the capacity spectrum method. This method is the concept of an equivalent linear system, wherein a linear system having reduced stiffness and increased damping is used to estimate the response of the nonlinear system. This procedure are conceptually simple, but the iterative procedure is time-consuming and may sometimes lead to no solution or multiple solutions. This paper presents a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of structures, without iterative computations, given by the structural initial elastic period and yield strength from the pushover analysis, especially for mixed building structure.

• Computers and Concrete
• /
• v.19 no.4
• /
• pp.405-411
• /
• 2017

Carbon Fiber Reinforced Plastic (CFRP) has commonly been used to strengthen existing RC structures. Wrapping the whole component with CFRP is an effective method and simple to execute. Besides, specific configuration of CFRP sheets (L, X and T shape) has also been considered in some experiments to examine CFRP effects in advance. This study aimed to provide an optimal CFRP configuration to effectively retrofit the beam-column connection using continuous material topology optimization procedure. In addition, Moved and Regularized Heaviside Functions and penalization factors were also considered. Furthermore, a multi-material procedure was also used to compare with the results from the single material procedure.