• 한국학교수학회논문집
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• 제23권4호
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• pp.523-556
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• 2020

이공계열 대학 신입생들이 함수의 극한, 함수의 연속과 관련된 기초 개념을 어느 정도 이해하고 있는지 조사·분석하였다. 조사 결과, 개념들을 연결하여 이해한 대학생들에 비해 그렇지 못한 대학생들이 많이 나타났다. 그러므로 대학 교양 수학을 지도하기 위해 대학 신입생들이 기초수학 개념을 어느 정도 연결하여 이해하고 있는지 조사·분석하여 대학생 개개인에게 적합한 교수·학습법을 적용할 필요성이 있다.

• 한국수학교육학회지시리즈A:수학교육
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• 제40권2호
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• pp.345-350
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• 2001

This study suggested a teaching method to improve intuitive understanding of the statistical basic concepts about the central limit theorem with experiment. It is very hard to understand about the concept of the central limit theorem in the school mathematics class. The result of this study experiment for the class of statistics education shows that the students and mathematics teachers were interesting at this experiment. They corrected their misunderstanding about the central limit theorem by discussion for the result of experiment with team members. I think that this study can help teachers to teach the students using the experiment method.

• 터널과지하공간
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• 제7권4호
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• pp.310-322
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• 1997

New limits of comfort boundary, psychological damage boundary and exposure limit for building residents by continuous and vibration are suggested. These limits are derived from the ISO 2631 and DIN 4150 regulations. A reasonable method to evaluate damages by vibrations is also suggested using the "total over-exposure of vibration" concept.; concept.

• East Asian mathematical journal
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• 제39권2호
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• pp.119-139
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• 2023

Most of calculus and real analysis are concerned with the study on continuous functions. Because of self-sustaining concept caused by everyday language, continuity has difficulties. This kind of viewpoint is strengthened with that teacher explains continuity by graph drawn ceaselessly and so finally confused with mathematics concept which is continuity and connection. Thus such a concept image of continuity becomes to include components which create conflicts. Therefore, we try to analyze understanding of continuity on university students by using the concept image as an analytic tool. We survey centering on problems which create conflicts with concept definition and image. And we investigate that difference of definition in continuous function which handles in calculus and analysis exists and so try to present various results on university students' understanding of continuity concept.

• 충청수학회지
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• 제32권1호
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• pp.69-86
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• 2019

In this paper, we introduce a concept of the ${\epsilon}_0$-limits of vector and multiple valued sequences in $R^m$. Using this concept, we study about the concept of the ${\epsilon}_0$-dense subset and of the points of ${\epsilon}_0$-dense ace in the open subset of $R^m$. We also investigate the properties and the characteristics of the ${\epsilon}_0$-dense subsets and of the points of ${\epsilon}_0$-dense ace.

• 한국안전학회지
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• 제26권5호
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• pp.1-6
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• 2011

Flame extinction and the chemistry of stoichiometric methane/air mixture were investigated numerically in the PSR(perfectly stirred reactor). For the study, PSR code was modified to be possible to unsteady calculation, and the sinusoidal fluctuation was subjected to the residence time. In the region of residence time far from the extinction limit, combustion mode was strongly dependent on the frequency. The low frequency excitation provided the quasi-steady behavior on the temperature and the concentrations of related species, but small variation of temperature was observed under high frequency. In the region of residence time near the extinction limit, the mixture subjected above 1 KHz was still reacting even though extinction had to be occurred under quasi-steady concept. The attenuation of extinction limit resulted from that chemical time was comparable to the flow time. The mean mole fractions of both NO and CO were almost same regardless of imposed frequency. However, the average mole fraction of $C_2H_2$ was decreased as increasing frequency, which implies that soot yield might be reduced at the higher frequency of flow excitation. The result provides the basic concept for flame stabilization, and it will be used to design a mild combustor.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1572-1579
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• 2005

New procedure for evaluation of creep reduction factor using performance limit strain concept was introduced and confirmed through the creep test results. To determine the performance limit strain of the textile geogrid used in this study, the Sherby-Dorm Plots were applied and the results were compared with the results that applied existed limit strain criteria (GRI test method GG-4). The limit creep strain of the geogrid samples that determined by using the Sherby-Dorm Plots were all 11%. This value is more higher than the existed criteria as 10%. From this 11% limit strain the creep reduction factors were calculated at 100,000 hours design. It was resulted in 1.45 for all of the geogrid samples(8t/m, 10t/m). Finally, when it was compared with the creep reduction factors that using 10% criteria, there were some decrease of reduction factor values about $0.06{\sim}0.14$.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1993년도 가을 학술발표회 논문집
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• pp.63-68
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• 1993

Soil nailing is a method of reinforcing natural deposits of soil with passive inclusions, called nails, of steel or other materials. Its purpose is mainly to increase the tensile and shear strength of the soil mass. This method has been widely used during the last two decades to stabilize steep slopes in several countries (France, Germany, USA, Japan, etc.). The design methods that have been mostly used are Davis method, German method, and French method which are based on limit equilibrium approaches, and Juran method which utilizes the kinematical limit equilibrium design concept. This paper is focussed on the evaluation of the available design methods(especially, the France, Davis and German design methods) through comparison with each different assumption for the failure surface, the concept of failure mechanism and the definition of safety factor. The parametric study to identify the effects of design parameters on the overall factor of safety has also been conducted. By considering the results along with the associated assumptions which have been postulated in the several methods, the applicability of the method for a given soil and nail conditions has been evaluated.

• 대한산업공학회지
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• 제36권2호
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• pp.108-116
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• 2010

The maintenance of a deteriorating system is often imperfect. Previous studies have shown that the imperfect preventive maintenance (PM) can reduce the wear out and aging effects of deteriorating systems to a certain level between the conditions of as good as new and as bad as old. In this paper, we employ the concept of the improvement factor in investigating two optimal PM policies; failure limit policy and periodic PM policy. We redefine the improvement factor model as a function of the cost of PM, using this concept, we derive the conditions of optimal PM policies and formulate expressions to compute the expected cost rate. Based on this information, the determination of the maintenance policies which minimize the cost rate is examined. Numerical examples for the Weibull distribution case are also given.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.309-314
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• 2007

Recently, the LRFD and the PSF based on structural reliability assessment have been applied to NPP designs in behalf of the conventional deterministic design methods. In the risk-informed structural integrity, it is especially possible to optimize design procedures considering cost, manufacturing and maintenance because the structural reliability concepts have confirmed the reliability for which a designer aims. Generally, in order to evaluate the PSF, the LRFD which is the design concept for evaluating safety factors respectively on the limit state function including load and resistance. This study certifies the concept and its applications of the PSF using the LRFD based on the structural reliability engineering.