• Journal of applied mathematics & informatics
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• 제13권1_2호
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• pp.183-194
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• 2003

We will explain a new method for obtaining the nearly optimal domain for optimal shape design problems associated with the solution of a nonlinear wave equation. Taking into account the boundary and terminal conditions of the system, a new approach is applied to determine the optimal domain and its related optimal control function with respect to the integral performance criteria, by use of positive Radon measures. The approach, say shape-measure, consists of two steps; first for a fixed domain, the optimal control will be identified by the use of measures. This function and the optimal value of the objective function depend on the geometrical variables of the domain. In the second step, based on the results of the previous one and by applying some convenient optimization techniques, the optimal domain and its related optimal control function will be identified at the same time. The existence of the optimal solution is considered and a numerical example is also given.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.88-93
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• 1998

This paper presents a new solution approach to moving obstacle avoidance problem for a mobile robot. A new concept avoidability measure(AVM) is defined to describe the state of a pair of a robot and an obstacle regarding the collision between them. As an AVM, virtual distance function(VDF) is derived as a function of the distance from the obstacle to the robot and outward speed of the obstacle relative to the robot. By keeping the virtual distance above some positive limit value, the robot avoids the obstacle. In terns of the VDF, an artificial potential field is constructed to repel the robot away from the obstacle and to attract the robot toward a goal location. At every sampling time, the artificial potential field is updated and the force driving the robot is derived form the gradient of the artificial potential field. The suggested algorithm drives the robot to avoid moving obstacles in real time. Since the algorithm considers the mobility of the obstacle as well as the distance, it is effective for moving obstacle avoidance. Some simulation studies show the effectiveness of the proposed approach.

• Journal of the Korean Data and Information Science Society
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• 제28권6호
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• pp.1557-1564
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• 2017

We take genomic sequences of high-dimensional low sample size (HDLSS) without ordering of response categories into account. When constructing an appropriate test statistics in this model, the classical multivariate analysis of variance (MANOVA) approach might not be useful owing to very large number of parameters and very small sample size. For these reasons, we present a pseudo marginal model based upon the Gini-Simpson index estimated via Bayesian approach. In view of small sample size, we consider the permutation distribution by every possible n! (equally likely) permutation of the joined sample observations across G groups of (sizes $n_1,{\ldots}n_G$). We simulate data and apply false discovery rate (FDR) and positive false discovery rate (pFDR) with associated proposed test statistics to the data. And we also analyze real SARS data and compute FDR and pFDR. FDR and pFDR procedure along with the associated test statistics for each gene control the FDR and pFDR respectively at any level ${\alpha}$ for the set of p-values by using the exact conditional permutation theory.

• Geomechanics and Engineering
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• 제20권5호
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• pp.421-432
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• 2020

Cutting of rocks is very common encountered in tunneling and mining during underground excavations. A deep understanding of rock-tool interaction can promote industrial applications significantly. In this paper, a distinct element method based approach, PFC^3D, is adopted to simulate the rock cutting under different operation conditions (cutting velocity, depth of cut and rake angle) and with various tool geometries (tip angle, tip wear and tip shape). Simulation results showed that the cutting force and accumulated number of cracks increase with increasing cutting velocity, cut depth, tip angle and pick abrasion. The number of cracks and cutting force decrease with increasing negative rake angle and increase with increasing positive rake angle. The numerical approach can offer a better insight into the rock-tool interaction during the rock cutting process. The proposed numerical method can be used to assess the rock cuttability, to estimate the cutting performance, and to design the cutter head.

• Clinical and Experimental Pediatrics
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• 제50권2호
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• pp.127-131
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• 2007

Fever of unknown origin (FUO) has been a convenient term used to classify patients who warrant a particular systemic approach to diagnostic evaluation and management. The greatest clinical concern in evaluating FUO is identifying patients whose fever has a serious or life-threatening cause when a delay in diagnosis could jeopardize successful intervention. Thorough history and complete physical examination are critical to uncover the etiologic diagnosis. Most cases of FUO in children are caused by atypical presentations of common diseases rather than by typical manifestations of rare disorders. Selection of diagnostic tests and speed of investigation should be guided by a knowledge of the disease severity, patient age, epidemiologic and geographic information, and any positive findings from a detailed history and physical examination. The three most common causes of FUO in children are infectious diseases, connective tissue diseases, and malignancy. In general, the prognosis of FUO in children is better than that of adults. Although the outcome is dependent on the primary disease process, fever abates spontaneously in most cases in whom the cause of fever remains unclear.

• 한국식생활문화학회지
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• 제27권5호
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• pp.445-458
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• 2012

This study was conducted to approach the Korean new food words for the years 1994-2005 from the stance of food ethics. The new food words were categorized into food industry, foodstuffs, cooking, various foods, processed foods, distribution, and consumer health. The principles of food ethics applied to new food words include a respect for life, justice, environmental preservation, priority of safety, and dynamic equilibrium. Seventy percent of new food words were ethically neutral, while 30% had significant ethical meaning. There were more words with a negative ethical meaning than with a positive one. All of the principles, except respect for life, could be successfully applied to new food words. Dynamic equilibrium was the most appropriate principle for the new food words, followed by a priority for safety, justice, and environmental preservation. The results of this study implied that moderation and balance is required in our modern dietary life.

• 대한치과의사협회지
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• 제51권11호
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• pp.604-609
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• 2013

Crown fractures are relatively common trauma to anterior teeth, and should be restored immediately in most cases. For those who suffer from unfortunate traumatic episode, the best treatment option should be minimally invasive approach. In the presence of fractured tooth fragment, reattachment procedure creates positive emotional response in the patient and simplifies the procedure and maintenance of the patient's original tooth anatomy and occlusion. Without fractured tooth fragment, next conservative option could be direct composite restoration which is based on minimal invasion concept. This article proposes simple and very conservative techniques that anyone can do in daily practice.

• KIEE International Transactions on Power Engineering
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• 제4A권4호
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• pp.178-191
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• 2004

This paper presents a new approach to HVDC system control for damping subsynchronous oscillation (SSO) involving HVDC converters and turbine generator shaft systems. This requires a novel eigenvalue analysis (NEA) program, derivation of HVDC system modeling considering steady-state conditions and dynamic conditions in the combined AC/DC system, and an appropriate control scheme. The method suggested makes possible the design of a subsynchronous oscillation damping controller (SODC) to provide positive damping torque for the range of torsional modes in combined AC/DC systems. There are three steps involved in the design of a SODC； first the worst torsional mode is determined using the NEA program, next the SODC parameters are designed for the range of that torsional mode, and then finally an off-line simultaneous time domain program such as PSCAD/EMTDC is used to verify the parameters of the SODC. The suggested SODC design method is applied to two AC/DC systems, and its practicality is verified using the PSCAD/EMTDC simulation program.

• 전기학회논문지
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• 제62권1호
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• pp.95-100
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• 2013

This paper presents a new state feedback control approach for communication networks based control systems in which control input and output observation time-delay natures are generally occurred in practice. We first establish a generic state feedback control framework based on well-known linear system theory. A maximum time-delay value which allows critical stability of whole control system are defined to make a positive definite Lyapunov function which is mathematically composed of controlled system states. We analytically derive its control parameters by using a steepest descent optimization method in order to guarantee a stability condition through Lyapunov theory. Computer simulation is numerically carried out for demonstrating reliability of the proposed NCS algorithm and a comparative study is accomplished to prove its superiority for which the traditional control approach for NCS is made use of under same simulation scenarios.

• 한국IT서비스학회지
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• 제9권4호
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• pp.135-150
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• 2010

In the age of digital convergence, it is expected that quality of life of human beings can be improved by converged devices and services. Researches concerning change of buying patterns and consumer behaviors in these contexts have to be progressed actively. To investigate future trend of consumer behaviors, we used focus group interview for Qualitative approach in the first step and then conducted questionnaire survey for experts in order to get validity and feasibility of research results. As result of research we suggested eight propositions by FGI for 20s target consumers. Additionally, on the basis of qualitative research, by questionnaire survey for 22 experts two perspectives of positive and negative views In future trends were proposed. Results can give lots of Implications and research motivations to academia, practices and workers in public policies who have interests in change of consumer behaviors, thinking styles, and life style under digital convergent environment.