• Journal of Industrial Technology
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• v.20 no.A
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• pp.257-267
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• 2000

It was difficult to apply conventional excavation methods in some sections from Seoul to Pusan high speed rail road construction of 1 lot 2, due to highway concrete road, gas pipe, water pipe and nearby factories with automatic control system machine. To excavate safely and efficiently in these sections new blast patterns were employed within allowable blast vibration level, by test blast and controlled vibration by sequential blast. Behaviors of the rock mass including convergence and displacement around tunnel were measured with construction works and the crack width in concrete wall was also monitored for controlling allowable limits. The results can be summarized as follow : 1. The allowable blast vibration level in structure site is less 1.0cm/sec for highway concrete, 0.5 cm/sec for gas pipe, water pipe and building housing and 0.3 cm/sec for automatic control system machine. 2. The convergence displacement, single rod extensometer and multi rod extensometer around tunnel and cracks in concrete wall were measured, it was confirmed that the measured values were converged within allowable level. 3. The empirical formular of ground vibrations with 90% confidence lines for PD-3 was given as follow. $$V_{90%}=45.549({\frac{D}{\sqrt{W}}})^{-1.353}$$

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.5
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• pp.613-623
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• 1999

A Lagrangian particle dispersion mode l(LPDM) coupled with the prognostic flow model based on nonequilibrium level 2.5 turbulence closure has been dcveloped to simulate the dispersion from an elevated emission source. The proposed model did not require any empirical formula or data for the turbulent statistics such as velocity variances and Lagrangian time scales since the turbulence properties for LPDM were calculated from results of the flow model. The LPDM was validated by comparing the model results against the wind tunnel tracer experiment and ISCST3 model. The calculated wind profile and turbulent velocity variances were in good agreement with those measured in the wind tunnel. The ground level concentrations along the plume centerline as well as the dispersion codfficients also showed good agreement in comparison with the wind tunnel tracer experiment. There were some discrepancies on the horizontal spread of the plume in comparison with the ISCST3 but the maximum ground level concentrations were in a good confidence range. The results of comparisons suggested that the proposed LPDM with the flow model was an effective tool to simulate the dispersion in the flow situation where the turbulent characteristics were not available in advance.

• Journal of Educational Research in Mathematics
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• v.9 no.1
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• pp.279-294
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• 1999

The level-based task learning had an effect on enhancing the math achievement of enrichment and ordinary classes. Besides, the analysis of mathematical attitude change showed that the level-based task learning took effect in the experimental class in every domain, including self-confidence, flexibility, will power, reaction and value, while it made little difference to the comparative class. The findings were as follows in detail. 1. The Outcome of the Achievement Test 1) The Enrichment Class In the first two tests, there were little differences in the enrichment class, But the disparity between the experimental and comparative classes became larger as this study advanced with 4.3 for the third test, 6.4 for the fourth and 6.1 for the fifth. 2) The Ordinary Class In the first to fifth achievement tests, the ordinary class made less difference than the enrichment class did. But there appeared some effect as this study progressed, since the mean grade disparity between the experimental and comparative classes was 2.1 for the first test, 3.5 for the second, 3.9 for the third, 4.4 for the fourth and 6.3 for the fifth. 3) The Supplementary Class The supplementary class showed no big difference in the first two tests. But, like the ordinary class, there was some effect with the lapse of the third 2.9 for the test, 3.2 for the fourth and 4.1 for the fifth. 2. The Change of Mathematical Attitude 1) The Experimental Class The task learning by level had a great deal of effect on the experimental class, as the pre-and post-comparative analyses showed that this class's grades were 5.1 for self-confidence, 10.8 for flexibility, 11.3 for will power, 9.7 for curiosity, 10.9 for reaction and 2.8 for value. 2) The Comparative Class The relative comparison between the comparative class and experimental class revealed that there was a hole effect on the comparative class. 3. The Outcome of Questionnaire Survey 1) They showed a positive reaction, as 40.1% of them answered the level-based task loaming served to raise their achievement, and 48.0% told so-so, and 11.9% replied they weren't helped by it. 2) The results after the experiment were;37.8% of the students say they under- stood practically everything while 12.6% of them say they under stood almost half. 3) The will to learn after the experiment shows dramatic changes between the two classes, The students in the enrichment class showed better will to learn than the students in the ordinary and supplementary classes did.

• Journal of Families and Better Life
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• v.25 no.6
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• pp.83-94
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• 2007

The purpose of this study was to examine the relationships between ego- resilience and stress coping styles of adolescents. The study also tried to identify differences on stress coping styles based on the level of ego- resilience of adolescents. Ego-resilience showed positive correlations with problem-focused and social support seeking coping styles and a negative correlation with an emotion-focused coping style. Canonical Correlation analysis revealed that self-confidence among four sub-domains of ego-resilience made the most outstanding contributions in predicting stress coping styles of adolescents. The problem-focused coping style had the highest correlation with ego-resilience among the four coping styles. The group of adolescents who had a higher level of ego-resilience reported more problem-focused and social support-seeking coping styles in stressful situations. The results of this study suggested that development of ego-resilience of adolescents who were in the midst of transitions and adjustment problems was important for effective coping strategies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.609-612
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• 2001

Rogowski coil is made having no ferromagnetic material in a core. So the coil cannot be driven into saturation. This result in that Rogowski coils may be calibrated at relatively low currents. and used with confidence at very high currents. However the lowest level of current that can be measured is limited by the sensitivity of the voltage measuring instrument and system noise. Therefore. geometrical effects were investigated in order to measure high sensitivity of low level current and the significant source of error was examined as well. In the results, the source of error was associated with coil designs. i.e. shape and uniformity of coil and a geometrical location of current source inside and outside of the Rogowski coil.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.609-612
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• 2001

Rogowski coil is made having no ferromagnetic material in a core. So the coil cannot be driven into saturation. This result in that Rogowski coils may be calibrated at relatively low currents, and used with confidence at very high currents. However the lowest level of current that can be measured is limited by the sensitivity of the voltage measuring instrument and system noise. Therefore, geometrical effects were investigated in order to measure high sensitivity of low level current and the significant source of error wa examined as well. n the results, the source of error was associated with coil designs, i.e. shape and uniformity of coil and a geometrical location of current source inside and outside of the Rogowski coil.

• Journal of the Korean Geographical Society
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• v.28 no.3
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• pp.193-199
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• 1993

The interannual fluctuation, trends and perio-dicties in summer rainfall of South Korea were analyzed primarily by using Mann-Kendall rank method and Power Spectrum analysis for the period from 1920 to 1985. Their relations to Indian summer monsoon rainfall have also been examined. Increasing or decreasing rainfall tendencies are not found in South Korea. In Power Spectrum alalysis, 2.5 years periods are predominent at the 95 per cent confidence level in south Korea as a whole and Pusan. Also the period of 11.0 years is found in Seou. There are another prominent spectral peaks at 2.4, 3.1, 6.2 and 7.3 years period, which are significant at 90 per cent confidence level.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1651-1658
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• 2001

It is necessary to evaluate fatigue strength and reliability of the connecting rod which is core part in automotive engine to assure the high level of durability of automobile. For this purpose, the loading conditions in automotive engine is obtained by the dynamic analysis. Based on these results, the critical section was identified by the finite element analysis. The fatigue strength under constant amplitude was evaluated and the mean of the fatigue limit at R = -2.27 derived from the staircase method was 311.2MPa. And the failure probability( F$\sub$p/ ) derived from the strength-stress interference model is 0.0003% at the 99.99% confidence level and the mean factor of safety was 4.2.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.281-286
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• 2011

Station structures, one of important infrastructures, which have been being operated since the 1970s, are especially vulnerable to even the medium-level earthquake and they could be damaged by long-term internal or external vibrations such as ambient vibrations. Recently, much attention has been paid to real-time monitoring of the fatal defect or long-term deterioration of civil infrastructures to ensure their safety and adequate performance throughout their life span. In this study, a structural health monitoring methodology using acceleration responses is proposed to evaluate the health-state of the station structures and to detect initial damage-stage. A damage index is developed using the acceleration data and it is applied to outlier analysis, one of unsupervised learning based pattern recognition methods. A threshold value for the outlier analysis is determined based on confidence level of the probabilistic distribution of the acceleration data. The probabilistic distribution is selected according to the feature of the collected data.

• The Mathematical Education
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• v.40 no.2
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• pp.179-194
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• 2001

The seventh curriculum put into operation gradually from first-year student in 2000 academic years of elementary school is subject to form and apply a step-wise level curriculum. Mathematics(correspond to junior high school course from 7th school year to 9th school year) should apply a step-wise level curriculum from 7th school year in 2001 academic years. Accordingly, mathematics teachers must diagnose actual conditions of educations, distribution tables of test results, step-wise teaching-studying programs etc. They also make proper plans suitable for actual situations of each school, prepare appropriate teaching materials and aids. I investigated preceding studies planned for preparation of putting into operation of a step-wise level curriculum. It showed that most of the studies were conducted at schools of medium or large scale and studies conducted at schools of small scale was rare. There were 113 small scale middle schools out of total 297 middle schools in Kyongsangbuk-do area in 2000. In this situation, I felt necessities of modeling of a step-wise level curriculum suitable for small scale schools. In this study, I modeled a step-wise level curriculum suitable for small scale middle schools, applied this model to 44 students in M middle school. I modeled two types of curriculum. One is a step-wise level curriculum that execute special supplementation process to students who do not complete 7-가 step successfully. The other is a step-wise level curriculum which is a regular model for a step-wise level of 7-나 step. I carried out an academic achievement test and intimacy test about mathematics before and after the application of the model. In this study, I found out that this model was very effective in academic achievement of students and helpful to declined students in scholarship. In the intimacy test, It was found out that most of the students gained confidence in mathematics, felt less anxiety, formed positive self consciousness. Therefore, I think that this model will be helpful to the application of the seventh step-wise level curriculum.