• 한국생산제조학회지
• /
• 제9권4호
• /
• pp.117-122
• /
• 2000

This paper presents an indirect compensation of thermal errors during machining , in which thermal error is modelled as a linear regression of temperatures measured at 4 specified positions. In this regression model, weighting coefficients of the measured temperatures were estimated by using the least square method. The grinding test with compensation , after 4 -hour warning-up operation before the test, showed that the maximum machining error of the work pieces was reduced to 12${\mu}{\textrm}{m}$ while it measured by 28${\mu}{\textrm}{m}$ without compensation . Furthermore the standard deviation of machining errors was also reduced from 8${\mu}{\textrm}{m}$ to 2${\mu}{\textrm}{m}$.

• 산업공학
• /
• 제11권3호
• /
• pp.15-22
• /
• 1998

A new improved algorithm in edge location to subpixel accuracy using decent-based weight to spatial information is proposed in this paper and applied to automated visual inspection(AVI) system. An application of the new edge operator as an edge detector is also provided and compared with Tabatabai and Lyvers edge detectors. The existing algorithms located edger to subpixel accuracy using least-square or moment-based methods. The algorithms also use only spatial information or grey-level values to locate edges. However, the proposed algorithm consider the weighted sum of grey-levels values of each edge pattern. The results show that the proposed algorithm is relatively less biased and has smaller standard deviation than the edge operations developed by Tabatabai and Lyvers in the presence of noise.

• Smart Structures and Systems
• /
• 제15권4호
• /
• pp.1159-1175
• /
• 2015

In this study, the effect of temperature variation on the wireless impedance monitoring is analyzed for the tendon-anchorage connection of the prestressed concrete girder. Firstly, three impedance features, which are peak frequency, root mean square deviation (RMSD) index, and correlation coefficient (CC) index, are selected to estimate the effects of temperature variation and prestress-loss on impedance signatures. Secondly, wireless impedance tests are performed on the tendon-anchorage connection for which a series of temperature variation and prestress-loss events are simulated. Thirdly, the effect of temperature variation on impedance signatures measured from the tendon-anchorage connection is estimated by the three impedance features. Finally, the effect of prestress-loss on impedance signatures is also estimated by the three impedance features. The relative effects of temperature variation and prestress-loss are comparatively examined.

• 설비공학논문집
• /
• 제11권4호
• /
• pp.518-527
• /
• 1999

The solubility and miscibility measurement apparatus has been developed and used to obtain data for refrigerant/oil mixture. The solubility and miscibility data for R-134a/46 ISO VG Polyalkylen Glycol(PAG) oil mixture are obtained over the temperature range from -20 to 6$0^{\circ}C$ with a 1$0^{\circ}C$ interval and the oil concentration range from 0 to 90wt%. Using the experimental data, an empirical model is developed to predict the solubility relations for R-134a/PAG oil mixture at equilibrium. The average root-mean-square deviation between measured data and calculated results from the empirical model is 4.2%. Raoult's rule and Flory-Noggins theory are also used to predict mixture behavior. Immiscibility is observed for R-134a/46 ISO VG PAG oil mixture at low oil concentrations of 4.6, 10.1, and 20.4wt%.

• 대한간호학회지
• /
• 제34권3호
• /
• pp.421-429
• /
• 2004

Purpose: This study is to evaluate the effects of drug abuse prevention program for elementary school students. Method: The design of this study is nonequivalent control group pretest-posttest design. The subjects of experimental group were 27 students and the subjects of control group were 25 students in fifth grade of elementary school in C City, Gyeongsangbuk-do. The experimental group had Drug Abuse Prevention Program, which was two days per week program, for 5 weeks. And post-test was carried out in the same way as the pre-test. Data analysis was done using frequency, percentage, mean, standard deviation, Chi-square test, t-test, Paired Samples t-test using with SPSS WIN 11.0. Result: the experimental group, to which drug abuse prevention program was given, was improved in knowledge of drug and unacceptable attitude of drug compared to the control group, but there were no significant differences of self-esteem and assertiveness between two groups. Conclusion: The drug abuse prevention program was effective to increase knowledge and attitude of drug in elementary school students.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
• /
• pp.315-318
• /
• 1995

The optimum design problem of a coat-hanger die is solved by the inverse formulation. The flow in the die is analyzed using three-dimensional model. The new model for the manifold geometry is developed for the inverse formulation. The inverse problem for the optimum die geometry is formed as the optimization problem whose objective function is the linear combination of the square sum of pressure gradient deviation at die exit and the penalty function relating to the measure of non-smoothness of solution. From the several iterative solutions of the optimization problem, the optimum solution can be obtained automatically while producing the uniform flow rate distribution at die exit.

• 대한가정학회지
• /
• 제42권12호
• /
• pp.31-54
• /
• 2004

The purpose of this research is to exam the attitudes of elderly people to dating. This research also investigates the differences of the elderly's attitudes to dating based on demographic, family relation, and social relation variables. Attitudes to elderly dating in this study included the perception, necessity, and difficulty of elderly dating. The sample consisted of 689 elderly Korean people. Data were analyzed by frequencies, mean, standard deviation, Chi-square test, t-test, and F-test. The results showed that there were statistically significant differences in elderly attitudes to dating according to demographic, family relation, and social relation variables. The findings of this study are described in the results section and the implications of these research findings are discussed.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
• /
• pp.673-678
• /
• 2000

This paper presents an indirect compensation of thermal errors during machining, in which thermal error is modeled as a linear regression of temperatures measured at 4 specified positions. In this regression model, weighting coefficients of the measured temperatures were estimated by using the least square method. The grinding test with compensation, after 4-hour warming-up operation before the test, showed that the maximum machining error of the work pieces was reduced to 12${\mu}{\textrm}{m}$ while it measured 28${\mu}{\textrm}{m}$ without compensation. Furthermore the standard deviation of machining errors was also reduced from 8${\mu}{\textrm}{m}$ to 2${\mu}{\textrm}{m}$.

• 산업공학
• /
• 제14권4호
• /
• pp.385-393
• /
• 2001

In this paper, a scheme of scheduling a bottleneck operation is presented for production planning of make-to-order. We focus on the problem of capacity-dependent processing time in which processing time of the bottleneck operation is not fixed, but varies with job sequence or equipment capacity. For this, a genetic algorithm is applied for job sequencing with an objective function of mean square of weighted deviation. An experimental study is implemented in power transformer plant and results are compared with those of the EDD rule. It shows that the genetic algorithm is relatively good for most cases.

• 대한전기학회논문지
• /
• 제33권9호
• /
• pp.355-363
• /
• 1984

An ideal and an approximate eauivalent circuits of a face-mounted PZT piezoelectric transformer were introduced from the equivalent circuit taking into account the mechanical loss of a PZT piezoelectric disk vibrator. And several expressions for the resonant frequencies and for the voltage ratios were derived from the approximate circuit of the transformer. From the experiments on the vltage ratios regarding the frequency variation without load and on the load variation at resonant frequency, it was found that the voltage ratio increased with the increase of load resistance and decreased sharply with the slight deviation from the resonant frequency, and that no-load voltage ratio at the resonant frequency was proportional to the product of the mechanical quality factor and the square of the electromechanical coupling factor of the vibrator.