• International Journal of Reliability and Applications
• /
• 제11권2호
• /
• pp.123-138
• /
• 2010

This paper investigates a mathematical model of a system composed of two non-identical unit parallel system with common-cause failure, critical human error, non-critical human error, preventive maintenance and two type of repair, i.e. cheaper and costlier. This system goes for preventive maintenance at random epochs. We assume that the failure, repair and maintenance times are independent random variables. The failure rates, repair rates and preventive maintenance rate are constant for each unit. The system is analyzed by using the graphical evaluation and review technique (GERT) to obtain various related measures and we study the effect of the preventive maintenance preventive maintenance on the system performance. Certain important results have been derived as special cases. The plots for the mean time to system failure and the steady-state availability A(${\infty}$) of the system are drawn for different parametric values.

• Structural Engineering and Mechanics
• /
• 제38권6호
• /
• pp.767-802
• /
• 2011

Developers of new finite elements or nonlinear solution techniques rely on discriminative benchmark tests drawn from the literature to assess the advantages and drawbacks of new formulations. Buckling benchmark tests provide a rigorous evaluation of finite elements applied to thin structures, and a complete and detailed set of reference results would therefore prove very useful in carrying out such evaluations. Results are usually presented in the form of load-deflection curves that developers must reconstruct by extracting the points, a procedure which is often tedious and inaccurate. Moreover the curves are usually given without accompanying information such as the calculation time or number of iterations it took for the model to converge, even though this type of data is equally important in practice. This paper presents ten different limit-point buckling benchmark tests, and provides for each one the reference load-deflection curve, all the points necessary to recreate the curve in tabulated form, analysis data such as calculation time, number of iterations and increments, and all of the inputs used to obtain these results.

• International Journal of Knowledge Content Development & Technology
• /
• 제3권1호
• /
• pp.19-29
• /
• 2013

Insights from the recent wealth of popular books on neuroscience are offered to suggest a strengthening of theory in information science. Information theory has traditionally neglected the human dimension in favour of 'scientific' theory often derived from the Shannon-Weaver model. Neuroscientists argue in excitingly fresh ways from the evidence of case studies, non-intrusive experimentation and the measurements that can be obtained from technologies that include electroencephalography, positron emission tomography (PET), functional magnetic resonance imaging (fMRI), and magnetoencephalography (MEG). The way in which the findings of neuroscience intersect with ideas such as those of Kahneman on fast and slow thinking and Csikszentmihalyi on flow, is tentatively explored as lines of connection with information science. It is argued that the beginnings of a theoretical underpinning for current web-based information searching in relation to established information retrieval methods can be drawn from this.

• 한국IT서비스학회지
• /
• 제2권2호
• /
• pp.121-134
• /
• 2003

To improve the quality of the services and to concentrate on the core capability, in public sector the IT outsourcing is recently being vitalized by the institutional support of the government for the entrusting non-government. Because the lots of general studies so far have simply focused on indicating fragmentary factors i.e. economical factors, risk factors, system factors, or induction objects, etc., they are insufficient in making the practical decisions, therefore we indicated systemized model extending over the whole range of the IT outsourcing to support substantial decision makings, and assorted 4 categories and drew considerable 55 factors from the literature study to materialize the previously considerable factors at each decision making stage. And the principal factors were drawn from each decision making category by a group of 11 experts. Besides, a henceforth plan for the application was also presented through an actual example of the IT outsourcing decision making process of 'M', a public enterprise.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 ITC-CSCC -1
• /
• pp.144-147
• /
• 2000

In this paper, we propose two receiver structures of the impulse radio (IR) system to improve its performance in multipath environments. Recently, the impulse radio system has drawn much attention for future high-speed wire-less communication services. The conventional IR receiver directly correlates received signals with the ideal reference waveform, which results in performance degradation in multipath environments. The Key idea of the proposed receiver structures is to reflect the multipath Characteristics into the IR receiver. One is to deconvolve the received waveform with estimates of the multipath gains to obtain the transmitted waveform while the other is to modify the reference waveform of the correlator according to the estimates of the multipath gains. We examine the performance of the proposed schemes for the statistical indoor wireless communication channel model using computer simulation.

• 마케팅과학연구
• /
• 제18권1호
• /
• pp.157-177
• /
• 2008

Sportswear, including sports shoes, becomes a common and popular category because it gives young people a more relax lifestyle and greater versatility and comfort. It is believed that consumers prefer products of developed countries to products of developing or underdeveloped countries. This study tries to compare consumer behaviors for sports shoes in China and Korea. Our research model analyzed relationships among country-of-origin, perceived quality, perceived price, brand image and purchase intention for sports shoes in Korea and China. The country-of-origin was not found to play a significant role in Korea. But it was found to positively influence perceived quality in China. Brand image was found to play an important role in influencing perceived quality and perceived price in Korea and China. Perceived quality was found to influence positively purchase intention in both countries. Perceived price was found to negatively influence purchase intention in China. Implications drawn from this study were discussed.

• 한국군사과학기술학회지
• /
• 제13권1호
• /
• pp.99-104
• /
• 2010

MDPREF(Multidimensional Preference Analysis) is a program for analysis of preferences. It is what is known as a vector model. This means that the objective of the MDPREF analysis is to identify a perceptual map displaying subject(attribute) vectors. To form the subject vectors visually, lines are drawn from the origin of the plot to each subject point. We analysis the defense industry infrastructure in fire power area by using MDPREF.

• 한국항해학회지
• /
• 제18권2호
• /
• pp.69-81
• /
• 1994

Studies on the ship's automatic navigation & berthing control have been continued by way of solving the ship's mathematical model, but the results of such studies have not reached to our satisfactory level due to its non-linear characteristics at low speed. In this paper, the authors propose a new berthing control system which can evaluate as closely as cap-tain's decision-making by using the FNN(Fuzzy Neural Network) controller which can simulate captain's knowledge. This berthing controller consists of the navigation subsystem FNN controller and the berthing subsystem FNN controller. The learning data are drawn from Ship Handling Simulator (NavSim NMS-90 MK Ⅲ) and represent the ship motion characteristics internally. According to learning procedure, both FNN controllers can tune membership functions and identify fuzzy control rules automatically. The verified results show the FNN controllers effective to incorporate captain's knowledge and experience of berthing.

• 산업경영시스템학회지
• /
• 제21권45호
• /
• pp.319-328
• /
• 1998

In this paper, the design of ALT(Accelerated Life Test) requires a sampling plan based on failure-censored(Type II censored) ALT with lognormal life distribution. Specially the environmental effect of products has been emphasized, so we considered the upper life limit as well as lower life limit in the ALT sampling plan. The optimal plan with a high stress and a low stress is used as test plan, and the total sample size for test and lot acceptability constant which minimize an asymptotic variance of maximum likelihood estimator of assumed model parameters and satisfy the given producer's risk and customer's risk are drawn out. These values can be acquired by means of the computer program that we coded for resolving the difficulty and complexity of calculation.

• 제어로봇시스템학회논문지
• /
• 제16권5호
• /
• pp.411-414
• /
• 2010

As high quality image is required for digital cameras in recent use, the image stabilization technique has drawn much attention to prevent image degradation from shaky disturbance by users. In this paper, the optical image stabilization (OIS) system for DSLR (Digital Single Lens Reflex) camera is considered. First, the analytic model of an OIS system is presented to demonstrate the mechanism of image destabilization due to unknown disturbance that causes blurry images on CCD sensor. Then, to enhance the stabilization performance, a sliding mode control based on the min-max nonlinear control is introduced. Through the experiments and simulations, the effectiveness of the proposed method will be verified.