• Geotechnical Engineering
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• v.11 no.4
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• pp.75-86
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• 1995

After open -ended model pipe pile, which was composed of inner tube and outer tube was driven by different installation methods, degradation in open -ended pipe pile capacity was studied during simulated horizontal seismic shaking, which was modeled by records of actual earthquake. Drgradation in ultimate capacity of open -ended pipe pile during simulated earthquake was about 20% in impact pile and was approached up to about 40% in vibratal pile. Most of degradation in ultimate pile capacity was occured in the outer shaft surface and degradations in outer skin friction, toe resistance of steel, and plugging force were about 80%, 10%, 10%, respectively. out of ultimate pile capacity. It appeared that this trend did not depend upon the different installation methods of pile.

• Journal of Elementary Mathematics Education in Korea
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• v.13 no.2
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• pp.141-161
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• 2009

Mathematical Communication ability can be more developed through sharing thoughts with others. Therefore when we instruct students in math, it is very important for teachers to provide them with opportunity to communicate mathematically. So this study provided open-ended problems in small-group collaborative learning. And we analyzed students' mathematical communication focused on the student's level of understanding. Furthermore, to improve students' mathematical communication ability, this study tries to attract the factors that we should consider the exact date for inserting the open-ended problems into a course of math and the student's level of understanding for selecting suitable open-ended problems.

• Journal of the Korean Chemical Society
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• v.50 no.5
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• pp.385-393
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• 2006

In this study, we analyzed the effects of science inquiry learning that applies open-ended hypothesis-testing learning model in a high school chemistry class of grade 11 in respect of science process skills, science-related attitude, and appreciation towards science class by cognitive level. Open-ended science inquiry learning activities on Metals and their applications unit in Chemistry I were developed and applied to the treatment groups while the conventional science activities were applied to the control groups. Four classes of 92 students in a high school located in Seoul were assigned into the treatment and control groups, respectively. According to the results in the test of science process skills, the students treated with the alternative experiments emphasizing open-ended hypothesis-testing obtained higher scores in experimental design, data conversion and description, and hypothesis test than those with conventional experiments but not in problem cognition and definition and hypothesis fixing'. There was negative effect on science-related attitude due to increased roles and tasks in the open-ended science inquiry learning activities.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.199-206
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• 2002

The bearing capacity of open-ended piles is affected by the degree of soil plugging, which is quantified by the incremental filling ratio, IFR. However, most design criteria for open-ended piles do not consider the variation of pile bearing capacity with IFR. In this study, new design equations for calculating the pile base and shaft load capacities, based on IFR value of the pile, were proposed using the results of model pile tests. A full-scale pile load test was also conducted on fully instrumented open-ended pile driven into gravelly sand. The IFR for the pile was continuously measured during pile driving. In order to check the accuracy of predictions made with the proposed equations, the equations were applied to two examples, including the pile load test preformed in this study. Based on the comparisons with the pile load tests results, the proposed equations appear to produce satisfactory predictions.

• Journal of the Korean School Mathematics Society
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• v.10 no.3
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• pp.303-322
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• 2007

This study is to investigate student's processes of problem solving using open-ended Geometric problems to understand student's thinking and behavior. One 8th grader participated in performing her learning in 5 lessons for June in 2006. The result of the study was documented according to Polya's four problem solving stages as follows: First, the student tended to neglect the stage of "understanding" a problem in the beginning. However, the student was observed to make it simplify and relate to what she had teamed previously Second, "devising a plan" was not simply done. She attempted to solve the open-ended problems with more various ways and became to have the metacognitive knowledge, leading her to think back and correct her errors of solving a problem. Third, in process of "carrying out" the plan she controled her solving a problem to become a better solver based on failure of solving a problem. Fourth, she recognized the necessity of "looking back" stage through the open ended problems which led her to apply and generalize mathematical problems to the real life. In conclusion, it was found that the student enjoyed her solving with enthusiasm, building mathematical belief systems with challenging spirit and developing mathematical power.

• Geotechnical Engineering
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• v.12 no.2
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• pp.85-94
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• 1996

Model pile tests, using a calibration chamber in which the stress state and the relative density can be controlled, were performed in order to study the effects of pile diameter on the plugging rate and bearing capacity of open-ended pile. The model piles used in the test series were devised so that the bearing capacity of an open-ended pile could be measured out into three components. The test results showed that fully plugging depth of an open -ended pile increased with increase in pile diameter and soil density. Moreover, it was found that unit plug capacity decreased with increase in pile diameter, though the penetration ratio or plugging rate of piles was constant. However, the existing formulae for estimation of plug capacity give plug capacity which is constant or increased with increase in pile diameter, when penetration ratio or plugging rate of piles is equal. Thus, it is proposed that the effect of pile diameter as well as plugging rate on bearing capacity of pile must be considered in plug capacity estimation.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.1
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• pp.11-21
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• 1998

During an earthquake, there are three main components of excitation : horizontal excitation of the ground, vertical excitation of the pile due to superstructure feedback produced by vertical excitation of the ground, and the seawater excitation induced by the vertical ground shaking, that is, "the seaquake." These excitations could have effects on the soil plugs in open-ended pie piles installed at offshore sites. In this study, seaquake excitation induced by the vertical ground shaking was simulated by pulsing the water pressure at the seabed. During a seaquake, due to the induced excess porewater pressure and pressure gradients in the soil, the capacity of open-ended pipe piles installed in a simulated sea depth of greate than 220 m was reduced serevely and the soil plugging resistance was degraded by more than 80% The soil plug was failed because of eh upward seepage forces that developed in the soil plug due to excess pore water pressure produced in the bottom of the soil plug during the seaquake, The compressive capacity of ar open-ended pile in a simulated sea depth of less than 220 m was reduced only by about 10% and the soil plug resistance was degraded by less than 5%.s than 5%.

• Research in Mathematical Education
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• v.10 no.3 s.27
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• pp.151-167
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• 2006

The open approach to teaching school mathematics in the United States is an outcome of the collaboration of Japanese and U. S. researchers. We examine the approach by illustrating its three aspects: 1) Open process (there is more than one way to arrive at the solution to a problem; 2) Open-ended problems (a problem can have several of many correct answers), and 3) What the Japanese call 'from problem to problem' or problem formulation (students draw on their own thinking to formulate new problems). Using our understanding of the Japanese open approach to teaching mathematics, we adapt selected methods to teach mathematics more effectively in the United States. Much of this approach is new to U. S. mathematics teachers, in that it has teachers working together in groups on lesson plans, and through a series of discussions and revisions, results in a greatly improved, effective plan. It also has teachers actively observing individual students or groups of students as they work on a problem, and then later comparing and discussing the students' work.

• Research in Mathematical Education
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• v.8 no.3
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• pp.123-144
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• 2004

There is a tradition of advocating the 'two basics' (basic knowledge and basic skills) in Chinese mathematics education. The direct consequence is that Chinese students are able to produce excellent performance in the international mathematics examinations and outstanding results in the international mathematics competitions. In this article, we will present why and how Chinese teachers teach the 'two basics,' and how combine the pupil's creativity with their 'two basics.' Open ended problem solving is a way to meet the goal. The following topics will be concerned: Culture background; the speed of computation; 'make perfect' ; Efficiency in classroom; Balance between 'two basics' and personal development. In Particular, Chinese mathematics educators pay more attentions to the link between open ended problem solving and the 'two basics' principal.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.1 s.92
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• pp.33-39
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• 2005

Complex permittivities of material in a wide bandwidth are measured by using an open-ended coaxial probe. To obtain a confident complex permittivity profile, the accuracy of measured reflection coefficients and the stability of the conversion model should be guaranteed in advance. In this paper, the sensitivity of our conversion model is analyzed by employing two instruments with different uncertainties. And various factors effected on the accuracy of measured reflection coefficients are investigated in experiment.