• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.1889-1910
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• 2017

This paper investigates a protocol so-called Adaptive Harvest Then Transmit (AHTT) for wireless powered communication networks (WPCNs) in multiple-input single-output (MISO) downlink systems, which assists in transmitting signals from a multi-antenna transmitter to a single-antenna receiver. Particularly, the power constrained relay is supplied with power by utilizing radio frequency (RF) signals from the source. In order to take advantage of multiple antennas, two different linear processing schemes, including Maximum Ratio Combining (MRC) and Selection Combination (SC) are studied. The system outage capacity and ergodic capacity are evaluated for performance analysis. Furthermore, the optimal power allocation is also considered. Our numerical and simulation results prove that the implementation of multiple antennas helps boost the energy harvesting capability. Therefore, this paper puts forward a new way to the energy efficiency (EE) enhancement, which contributes to better system performance.

• 가정과삶의질연구
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• 제17권3호
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• pp.131-144
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• 1999

The purpose of this study was to examine the influences of the consumer's knowledge the consumer's attitude the family characteristics and the variables on consumer socialization to the consumer's functions of homemakers. The samples were selected from 428 homemakers living in Kwangju, Frequncies Perentiles Means Standard Deviations Multiple regression Path analysis were used as statistical analysis The results were sumarized as follows: Resulting from multiple regression analysis the consumer's function had the positive linear relationships with variables such as family life cycles interaction with family consume knowledge and consumer attitude. The most influential variable was consumer attitude.

• 가정과삶의질연구
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• 제24권2호
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• pp.73-92
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• 2006

This paper investigates the causal relationships between financial attitudes, spending behaviors and the financial satisfaction of adolescent consumers. The study used Cronbach' $\alpha$, t-test, one-way ANOVA, Duncan's multiple range test, multiple regression and path analysis for statistical analysis and applied it to 1,252 questionnaires. The results are summarized as follows: Path analysis revealed that the financial satisfaction of adolescents had a direct linear relationship with variables such as grade, sex, financial attitudes. (financial situation compared to past and financial situation compared to others) and types of spending behaviors (planned, conspicuous and excessive). Planned spending behavior was the most influential variable on financial satisfaction. Planned spending behavior had positive linear relationship with the attitude toward the past financial situation. Conspicuous spending behavior had positive linear relationships with the attitudes toward the past financial situation and the financial situation compared to others. However, it showed negative relationship with the attitude toward a future financial situation. Impulsive spending behavior had a positive relationship with the attitude toward others' financial situation. Excessive spending had a positive relationship with the attitude toward a past financial situation but showed a negative relationship to the attitude toward others' financial situation.

• 품질경영학회지
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• 제21권1호
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• pp.161-170
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• 1993

This study attempts to present the linear regression analysis that involves more than one regressor variable, because regression analysis is the most widely used statistical technique for describing, predicting and estimating the relationships between given data. The model of multiple linear regression may be solved directly by the two linear programming methods, i.e., to minimize the sum of the absolute deviation (MSD) and to minimize the maximum deviation(MMD). In addition, some results was compared to each techniques for accuracy and tested to the validity of statistical meaning.

• International Journal of Automotive Technology
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• 제4권2호
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• pp.101-108
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• 2003

There are a lot of factors that influence automotive fuel economy such as average trip time per kilometer, average trip speed, the number of times of vehicle stationary, and so forth. These factors depend on road conditions and traffic environment. In this study, various driving data were measured and recorded during road tests in Seoul. The accumulated road test mileage is around 1,300 kilometers. The objective of the study is to identify the driving patterns of the Seoul metropolitan area and to analyze the fuel economy based on these driving patterns. The driving data which was acquired through road tests was analysed statistically in order to obtain the driving characteristics via modal analysis, speed analysis, and speed-acceleration analysis. Moreover, the driving data was analyzed by multivariate statistical techniques including correlation analysis, principal component analysis, and multiple linear regression analysis in order to obtain the relationships between influencing factors on fuel economy. The analyzed results show that the average speed is around 29.2 km/h, and the average fuel economy is 10.23 km/L. The vehicle speed of the Seoul metropolitan area is slower, and the stop-and-go operation is more frequent than FTP-75 test mode which is used for emission and fuel economy tests. The average trip time per kilometer is one of the most important factors in fuel consumption, and the increase of the average speed is desirable for reducing emissions and fuel consumption.

• Interaction and multiscale mechanics
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• 제5권1호
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• pp.27-40
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• 2012

The two-dimensional incompressible flow of a linear viscoelastic fluid we considered in this research has rapidly oscillating initial conditions which contain both the large scale and small scale information. In order to grasp this double-scale phenomenon of the complex flow, a multiscale analysis method is developed based on the mathematical homogenization theory. For the incompressible flow of a linear viscoelastic Maxwell fluid, a well-posed multiscale system, including averaged equations and cell problems, is derived by employing the appropriate multiple scale asymptotic expansions to approximate the velocity, pressure and stress fields. And then, this multiscale system is solved numerically using the pseudospectral algorithm based on a time-splitting semi-implicit influence matrix method. The comparisons between the multiscale solutions and the direct numerical simulations demonstrate that the multiscale model not only captures large scale features accurately, but also reflects kinetic interactions between the large and small scale of the incompressible flow of a linear viscoelastic fluid.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1072-1077
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• 2004

This paper provides a new approach to analyze the stability of a general multi-link TCP Vegas, which is a kind of feedback-based congestion algorithm. Whereas the conventional approaches use the approximately linearized model of the TCP Vegas along equilibrium pints, this approach models a multi-link TCP Vegas network in the form of a piecewise linear multiple time-delay system. And then, based on the exactly characterized dynamic model, this paper presents a new stability criterion via a piecewise and multiple delay-dependent Lyapunov-Krasovskii function. Especially, the resulting stability criterion is formulated in terms of linear matrix inequalities (LMIs).

• 한국통신학회논문지
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• 제16권7호
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• pp.598-609
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• 1991

단일 직선선로의 불요 복사에 대한 이론을 확장하여, PCB와 같이 다수의 비직선 선로에 임의의 선로가 개별적으로 전송될때 이 PCB 전체에서 발생하는 불요전자파 복사의 크기를 정량적으로 구할수 있는 보다 일반화된 해석 방법을 얻기 위하여 복사현상의 회로모형을 배열 안테나 이론에 적용하여 구했다. 제안된 해석방법의 타당성을 확인하깅 ㅟ해 2개 및 3개의 사로 다른 임의의 비직선 각종선로에 600MHz의 신호원을 인가하여 시뮬레이션한 결과와 측정된 불요복사 특성과 비교하여 서로 잘 일치함을 확인하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1256-1261
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• 2004

Nonlinear Response Optimization using Equivalent Static Loads (NROESL) method/algorithm is proposed to perform optimization of non-linear response structures. It is more expensive to carry out nonlinear response optimization than linear response optimization. The conventional method spends most of the total design time on nonlinear analysis. Thus, the NROESL algorithm makes the equivalent static load cases for each response and repeatedly performs linear response optimization and uses them as multiple loading conditions. The equivalent static loads are defined as the loads in the linear analysis, which generates the same response field as those in non-linear analysis. The algorithm is validated for the convergence and the optimality. The function satisfies the descent condition at each cycle and the NROESL algorithm converges. It is mathematically validated that the solution of the algorithm satisfies the Karush-Kuhn-Tucker necessary condition of the original nonlinear response optimization problem. The NROESL algorithm is applied to two structural problems. Conventional optimization with sensitivity analysis using the finite difference method is also applied to the same examples. The results of the optimizations are compared. The proposed method is very efficient and derives good solutions.

• 한국안전학회지
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• 제29권6호
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• pp.151-157
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• 2014

This study deals with the rear-end collision at roundabouts. The purpose of this study is to develop the accident models of rear-end collision in Korea. In pursuing the above, this study gives particular attention to developing the appropriate models using Poisson, negative binomial model, ZAM, multiple linear and nonlinear regression models, and statistical analysis tools. The main results are as follows. First, the Vuong statistics and overdispersion parameters indicate that ZIP is the most appropriate model among count data models. Second, RMSE, MPB, MAD and correlation coefficient tests show that the multiple nonlinear model is the most suitable to the rear-end collision data. Finally, such the independent variables as traffic volume, ratio of heavy vehicle, number of circulatory roadway lane, number of crosswalk and stop line are adopted in the optimal model.