• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.57-63
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• 1999

A thin metal plate such as detent spring has the shape deformation due to the phenomenon of spring back after press machining and heat treatment process. This requires the correction of spring shape and force in final inspection process. To do correction of the shape deformation the impact force is manually applied to the bended part of detent spring after measuring the shape deformation and spring force. To develop the automatic spring force correction system, applied force of occurring plastic deformation must be derived from the experimental method. But frequent change of spring shape and material makes it difficult to accomplish the experimental method to be applied. This paper describes the analytical method for detent spring force correction system is to be substituted for the experimental method. FEM(Finite Element Method) is used to find the boundary value between elastic and plastic deformation in the analytical method. To confirm the validity of the analytical method, the result of two methods is compared each other at various applied force conditions. It shows that the simulation result of the analytical method is consistent with the result of the experimental method within the error bound ${\pm}$5%. The result of this paper is useful for development of the automatic spring correction system and reduction of the complicated and tedious processes involved in experimental method.

• Particle and aerosol research
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• v.5 no.1
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• pp.17-27
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• 2009

Particle deposition on a semiconductor wafer larger than 100 mm was studied experimentally and numerically. Particularly the electrostatic effect on particle deposition velocity was investigated. The experimental apparatus consisted of a particle generation system, a particle deposition chamber and a wafer surface scanner. Experimental data of particle deposition velocity were obtained for a semiconductor wafer of 200 mm diameter with the applied voltage of 5,000 V and PSL particles of the sizes between 83 and 495 nm. The experimental data of particle deposition velocity were compared with the present numerical results and the existing experimental data for a 100 mm wafer by Ye et al. (1991) and Opiolka et al. (1994). The present numerical method took into consideration the particle transport mechanisms of convection, Brownian diffusion, gravitational settling and electrostatic attraction in an Eulerian frame of reference. Based on the comparison of the present experimental and numerical results with the existing experimental results the present experimental method for a 200 mm semiconductor wafer was found to be able to present reasonable data.

• Journal of the Korean Society for Library and Information Science
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• v.18
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• pp.277-325
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• 1990

The purpose of this study was to determine the effectiveness of instructors' utilization of the reserve collection in the university library. To accomplish this, an experiment-and-questionnaire study was done by selecting an experimental group for whom the teaching method utilizing the reserve collection was used and a control group for whom the method was not used. An experimental group and a control group studied were as follows: (1) Students take the 'Comparative Politics' course in the Department of Political Science. (2) Students take the 'History of 'English Literature' course III the Department of English Language and Literature. The data to test the hypothesis were analyzed by SPSS/PC+ routine. The results are as follows: (1) There were significant differences between the experimental group and the control group in academic achievement(T(228)=6.69, P<.01). To investigate the difference in effect by major, the one-way analysis of variance was employed. According to the results, there were significant differences between the experimental group and the control group In the Department of Political Science and the Department of English Language & Literature. Therefore, students for whom the teaching method utilizing the reserve collection was used have higher academic achievement than those for whom the method was not used. (2) As for the degree of utilizing the library and its materials, there were significant differences between the experimental group and the control group(T(228)=8.87, P<.01). As for the results of the one-way analysis of variance to investigate the difference in effect by major, there were significant differences between the experimental group and the control group in both departments. As for the degree of utilizing library catalogues and bibliographical tools, there were significant differences between the experimental group and the control group(T (228)=8.55, P<.01). As stated earlier, the one-way analysis of variance to investigate the difference in effect by major has shown that there were significant differences between the experimental group and the control group in both departments. As for the degree of sincerity in doing homework and writing papers, there were significant differences between the experimental group and the control group(T(176)=8. 03, P<.01). To investigate the difference in effect by major, the one-way analysis of variance was again employed. According to the results, there were again significant differences between the experimental group and the control group in both departments. So, the students for whom the teaching method utilizing the reserve collection was employed used library catalogues and bibliographical tools much more than those for whom the method was not employed, and were more sincere in doing homework and writing papers. (3) There were also significant differences between the experimental group and the control group in degree of satisfaction in taking the course (T (228) = 6.61, P<.01). The results of the one-way analysis of variance to investigate the difference in effect by major was that there were significant differences between the experimental group and the control group in both departments. Therefore, the degree of satisfaction of students who were taught by the teaching method utilizing the reserve collection is higher than that of those who were not taught by the method. On the other hand, the responses of the experimental groups of two departments as to the degree of satisfaction with their teaching method was investigated. The result shows that students who took the 'Comparative Politics' course in a small class which employed the seminar method were higher in degree of satisfaction with the teaching method than students who took the 'History of English Literature' course III a large class which employed a lecture-oriented teaching method.

• The Journal of Korean Academic Society of Nursing Education
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• v.15 no.1
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• pp.120-127
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• 2009

Purpose: In the literature power analysis in experimental studies is often executed and reported falsely. This descriptive study was done to promote the correct application of the Cohen(1988)'s power analysis method. Method: Articles of experimental studies from a nursing journal were selected and reviewed to examine the uses of and the reports on the power analysis process. Also, the appropriate power analysis process was discussed with an example of the most common experimental design, an independent two-group design with t test analysis plan. Result: Around half the experimental studies examined reported that they carried out power analysis. Cohen's method was the most frequently utilized but with accuracy in question. Conclusion: Power analysis to estimate sample size is the interplay between alpha, power, and effect size, and other factors in the case of t test analysis. Researchers should have a clear understanding of how to apply the Cohen's power analysis method so they do not produce poorly estimated sample sizes.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.307-315
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• 2001

The purpose of this study was to provide the evaluation and prediction of strengths of SB latex modified concrete(LMC) using a statistical method and factorial experimental design method. The main experimental variables were as follows ; W/C ( 4 levels ; 31, 33, 35, 42%), S/a( 2 levels ; 55, 58%) and L/C(2 levels ; 5, 15%). The compressive strength and flexural strength of LMC were selected as a factor of response. The statistical method was carried out to analyze the results, together with factorial experimental design method and response surface method. The analysis showed that if L/C had been 15%, W/C appeared to be around 33% to achieve the design strength of $350kgf/cm^2$. In this case, the flexural strength and the slump came to around $68kgf/cm^2$ and 18cm, respectively. Eventhough the L/C varied, the design strength and W/C could be predictable together with slump value and flexural strength. As a result of series of experiments in this study, W/C and L/C were proved to be the main factors influencing on the compressive and flexural strength of LMC. Both of strength and slump values could be predictable from the mixing proportion of LMC.

• English Language & Literature Teaching
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• v.10 no.2
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• pp.89-111
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• 2004

The purpose of this article is to study the effect of finger play teaching method on the reproduction of children's English words. The hypotheses are as follows: 1) there will be the difference of the reproduction of children's English words between the experimental group(that is taught by finger play teaching method) and the controlled group (that is taught by only oral teaching method). 2) there will be the difference of children's retention capacity of reproducing English words between the experimental group and the controlled group, The researcher made the time series data The measure tool was the check list for reproduction test of children's English words that was made by Run-Soon Oh and J. Eden(2004). The researcher analyzed the data using the Repeated Measures ANOVA and the Analysis of Covariance. The findings of research are as follows: 1) the more the frequency of teaching increases, the more there are the difference of reproducing English words according to frequencies and groups. The reproduction capacity of the experimental group is better than that of the controlled group. A degree of statistical significance is p<.001. 2) The difference of retention capacity of reproducing English words between the experimental group and the controlled group is a statistical significant, p<.05. The experimental group is better than the controlled group.

• Journal of Korean Library and Information Science Society
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• v.28
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• pp.93-135
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• 1998

The purpose of this study was to compare the effectiveness of programmed instruction versus lecture and discussion method on the knowledge of basic reference sources among undergraduate library and information science students. The hypotheses of the study were: 1. Programmed instruction will be more effective than the lecture/discussion method with regard to academic achievement. 2. There will be a significant difference in learning time between the experimental and the control groups. Seventy-eight library and information science students were participated m the study from the two universities in Chungchong Province. A programmed instruction manual, including 4-types of reference sources-dictionary, encyclopaedia, bibliography, indexes and abstracts, 40-item multiple choice post-test, and a questionnaire for the students' attitude toward programmed instruction were developed specifically for this research. The post-test only control-group design was selected for this experimental study. Students were given instruction on the specific reference titles in dictionary, encyclopedia, bibliography, indexes and abstracts. The control group was instructed by the lecture and discussion method while the experimental group completed a programmed instruction manual by themselves. Both the control and the experimental group were tested right after the instruction of 4-types of reference sources. In addition, a questionnaire asking students' attitude toward programmed instruction was administered to the experimental group. The findings from this study are summarized as follows: 1. The results showed that there were no significant difference in the mean of the post test score between the two groups. Therefore, programmed instruction is viable as an alternative method of instruction in the teaching of reference sources. 2. There was a significant difference in the mean of time spending for the leaning of bibliography, indexes and abstracts between the two groups. Accordingly, programmed instruction proved to be more efficient than the conventional lecture/discussion method in terms of learning time. 3. Students showed positive response to programmed instruction and evaluated it very interesting and challenging. In conclusion, the programmed instruction method was just as effective as the lecture/discussion method in the teaching of reference sources. And students' attitude toward the programmed instruction was favorable enough to secure a continued use of this method for the teaching of reference sources.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.427-432
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• 1999

An electrci method for the rapid determination of chloride diffusion coefficient in concrete is proposed considering the electrical migration term in the Nernst-Plank equation. The experimental set-up for this method is basically that for PD index by Dhir, excluding some change in the experimental parameter values in consideration of reliability, simplicity and rapidity of the accelerated test method. Experimental results show that 30mm of specimen thickness, 10 volt of supplied potential, and 5M of chloride ion concentration are optimal

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.328-334
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• 2001

Up to now. vibration analysis and vibration engineering have been developed, encompassing the aspects of both experimental and analytical techniques. Using experimental modal analysis or modal testing, the mode shapes and frequencies of practical structure can be measured accurately. Curve-Fitting Method is realized through experimental modal identification. In the experimental modal parameter estimation, the estimation of modal damping factor is difficult for complicated and large structure. Also numbers of Selected mode are determined before the procedure. This paper describes the vibration shape of the super-structure model of ship through experimental modal analysis.

• Journal of KSNVE
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• v.6 no.3
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• pp.317-323
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• 1996

This paper proposes the method of experimental structural dynamic modification of fixture for environmental vibration test control. This method can predict the responses at any points on the fixture utilizing the experimental data, and structural dynamic modification of fixture is made using the predicted responses for the spectra at the specimen attachment points to meet the specified reference spectrum. From the results of controlling the fixture before and after modification by conventional control method and optimal reference spectrum, which has been previously reported by the authors, the proposed method is shown to be an effective one.