• Journal of Mechanical Science and Technology
• /
• 제15권10호
• /
• pp.1369-1379
• /
• 2001

This paper focuses on a development of a sensor system measuring locations of a vehicle to localize a mobile robot while it tracks on the track (location sensor) . Also it focuses on a system configuration identifying the vehicle's orientation and distance from the object while it is stationary at certain station (position sensor) . As for the location sensor it consists of a set of sensors with a combined guiding and counting sensor, and an address-coded sensor to localize the vehicle while moving on the rail. For the position sensor a PSD (Position Sensitive Device) sensor with photo-switches sensor to measure the offset and orientation of the vehicle at each station is introduced. Both sensor systems are integrated with a microprocessor as a data relay to the main computer controlling the vehicle. The location sensor system is developed and its performance for a mobile robot is verified by experiments. The position measuring system is proposed and is robust to the environmental variation. Moreover, the two kinds of sensor systems guarantee a low cost application and high reliability.

• 한국직업건강간호학회지
• /
• 제30권4호
• /
• pp.167-174
• /
• 2021

Purpose: This study aimed to identify how job stress and teaching efficacy impacted organizational commitment. Methods: Data were collected from 158 nursing professors via an online survey, from Jan to June 2019. Results: The study found that four factors affected the organizational commitment of nursing professors: i) type of nursing institution in which they are currently employed (β=-.16, p=.030), ii) position as an assistant professor (β=-.37, p=.012) and an associate professor (β=-.44, p=.002), iii) salary in the 50-59 million won range (β=.20, p=.024), and above 60 million won (β=.41, p<.001), and iv) professor's teaching efficacy (β=-.18, p<.016). Conclusion: To increase the organizational commitment of four-year university professors, job characteristics should be considered. In the case of lower positions and salaries, additional compensation and programs that increase school affiliation should be introduced. Teaching methods training, lecture evaluation monitoring programs, and clinical training may also improve teaching efficacy.

• Communications for Statistical Applications and Methods
• /
• 제3권3호
• /
• pp.25-30
• /
• 1996

In discriminant analysis the procedures commonly used to estimate the dimensionality involve testing a sequence of dimensionality hypotheses. There is a problem with the size of the test since dimensionality hypotheses are tested sequentially and thus they are actually conditional tests. The focus of this paper is to investigate in asymptotic sense what happens to the sequential testing procedure if the assumption of normality does not hold.

• Communications for Statistical Applications and Methods
• /
• 제3권3호
• /
• pp.75-81
• /
• 1996

Polynomial measurement error model(MEM) with one predictor is considered. It is briefly mentioned that Chan and Mak's generalized least squares estimator(GLSE) can be derived more easily if Hermite polynomial concept is applied. It is proved that GLSE derived using new procedure is equivalent to the estimator obtained from corrected score function. Finally, much simpler proof of the asymptotic behavior of GLSE than that of Chan and Mak is provided. Much simpler formula of asymptotic covariance matrix of GLSE is a part of that proof.

• Journal of the Korean Statistical Society
• /
• 제5권2호
• /
• pp.143-158
• /
• 1976

The purpose of this article is, first, to argue that the fertility cannot be reduced rapidly through widerspread diffusion of contraceptive practices which has been the main drive of the national policy in population control, because there involves the inescapable externalites in procreation, second, family sizes tend to be larger because of the financial externalities arising from government subsidies to families with children, and finally, the decreasing relative risk aversion of households with wealth may induce the poor to have large family sizes.

• Journal of the Korean Statistical Society
• /
• 제8권2호
• /
• pp.139-163
• /
• 1979

Utilization of the aggregation concept applied in economics has been a traditional way of describing the state of an economic system and of predicting the future economic conditions. In addition, certain aggregate variables have also played a crucial role as indicators of the business cycle. Quick examples would be the price index, the productivity changes, the industrial production index, GNP, and so on. The methods of aggregation could be either simple summations, like GNP, or sophisticated weighted average, like the price index.

• Communications for Statistical Applications and Methods
• /
• 제6권1호
• /
• pp.305-318
• /
• 1999

In this paper we derive the higher order expansions of the first four cumulants of multi-dimensional Maximum Likelihood Estimator (MLE) under the general parametric model up to and including terms of order O({{{{ {n }^{-1 } }}}}) Also we obtain the explicit form of the expansion of the normalizing trans formation of multi-dimensional MLE and show that the suggested normalizing process is much better than the normal approximation based on central limit theorem through example.

• Communications for Statistical Applications and Methods
• /
• 제6권2호
• /
• pp.467-478
• /
• 1999

This paper deals with the problem of change-point estimation where there is one level change in location with iid errors. A change-point estimator using rank average is proposed with the proof of its consistency. A comparison study of various change-point estimators is done by simulation on the mean the proportion and the variance when the errors are from the normal and the double exponential distributions.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1990년도 PROCEEDINGS OF THE FIRST KOREA-JAPAN JOINT GEOTECHNICAL SEMINAR ON EXCAVATION and TUNNELING IN URBAN AREAS
• /
• pp.163-175
• /
• 1990

A main factor in the design of excavation in an urban area is the movements. The finite element method provides rational predictions of excavation behaviour, yet practical engineers may find difficulties in applying it to the actual field case. In this study, factors affecting the excavation behaviour are considered in details and the applicability of the finite element method to the actual field excavation cases is presented. Numerical examples are analyzed to provide results of parametric study on the affecting factors.

• Communications for Statistical Applications and Methods
• /
• 제3권1호
• /
• pp.257-265
• /
• 1996

We consider nonstationary autoregressive autoregressive process with infinite variance of error. In the case of infinite cariance, the limiting distribution of the estimated coefficient is different from that under the finite cariance assumption. In this paper we show that the bootstrap method can be used to approximate the distribution of ordinary least squares estimator of the coefficient in the first order random walk process with infinite variance through some empirical studies and we suggest a test procedure based on bootstrap method for the unit root test.