• Magazine of the Korean Society of Agricultural Engineers
• /
• v.41 no.1
• /
• pp.86-96
• /
• 1999

Laboratory experiment was performed for the TDR to measure the soil moisture, and the results, were compared with the design water content and the one measured by oven-try method. Sand and kaolinite were used . Varaiables for the experiment were water content (10-50%), void ration (0.7 -1.3), mixture rate of kaolinite (10-30%), and measurement methods (TDR and oven-dry). In all cases , TDR method showed very accurage and reliable results , and average error and error range were far lews than the oven-dry method which is widely used. Considerable error was noticed when water contnet was 50% where saturation was achieved for both methods. Therefore, TDR was thought to be applicable to the field moisture measurement if it is unsaturated. For field scale application of TDR, more research and verification of the accuracy with diverse soil conditions including physical ,chemical and mineral properties are recommended.

• Journal of Korean Society of Rural Planning
• /
• v.4 no.2
• /
• pp.20-28
• /
• 1998

A small wastewater collection system for rural area was reviewed and the small diameter gravity (SDG) was thought to be the most appropriate. The pilot-scale field experiment was performed for 15 months and the result is presented. The wastewater used for experiment was the effluent of septic tank in Kon-Kuk University, and components are similar to normal domestic wastewater. The SDG experimental system included 2" PVC pipe and reverse-sloped lower section is included. No clogging problem by solids was experienced at the points where flow direction changed. The pipe-breaking by freezing was experienced during the cold weather, thus proper protection may be required where severe weather is expected.

• Journal of Korean Elementary Science Education
• /
• v.38 no.2
• /
• pp.163-172
• /
• 2019

This study explored elementary teachers' perceptions on the essential features of science inquiry, the appropriateness of inquiry activities to science inquiry, and the essential features of inquiry by inquiry activities. 85 elementary teachers' perceptions were investigated using Likert scale survey, and 7 teachers were interviewed. The results are as follows. First, the features that elementary teachers perceived the most essential were 'Engaging students in evaluating their explanations in light of alternative explanations' and 'Engaging students in communicating and justifying their explanations'. Second, The inquiry activities that teachers thought the most appropriate to science inquiry were 'experiment' and 'project'. On the other hand, the perceptions on 'discussion' and 'field trip' were relatively low. Third, the inquiry activity that showed the highest mean score of five essential features of inquiry was 'experiment' while the mean score of 'field trip' was the lowest. Educational implications about the science inquiry were discussed.

• Journal for History of Mathematics
• /
• v.31 no.2
• /
• pp.73-91
• /
• 2018

This study begins with the awareness of problem that the education of mathematics teachers has failed to link the limit and the infinite set conceptually. Thus, this study analyzes the historical and reciprocal development of the limit and the infinite set, and discusses how to improve the education of these concepts and their relation based on the outcome of this analysis. The results of the study confirm that the infinite set is the historical tool of linking the limit and the real numbers. Also, the result shows that the premise of 'the component of the straight line is a point.' had the fundamental role in the construction of the real numbers as an arithmetical continuum and that the moral certainty of this premise would be obtained through a thought experiment using an infinite set. Based on these findings, several proposals have been made regarding the teacher education of awakening someone to the fact that 'the theoretical foundation of the limit is the real numbers, and it is required to introduce an infinite set for dealing with the real numbers.' in this study. In particular, by presenting one method of constructing the real numbers as an arithmetical continuum based on a thought experiment about the component of the straight line, this study opens up the possibility of an education that could get the limit values psychologically connected to the infinite set in overcoming the epistemological obstacle related to the continuum concept.

• Journal of The Korean Association For Science Education
• /
• v.16 no.4
• /
• pp.451-460
• /
• 1996

The ethical issue is one of the most important themes in both science and environmental education. Especially related to the right of other species, animal dissection has been brought about two contradictory attitudes. In spring 1996, a survey was conducted to assess the status of animal dissection in secondary schools and the awareness of 94 biology teachers and 422 secondary students toward animal dissection. And the meaning of animal dissection in biology class was discussed in terms of environmental education. The findings were as follows: First, most of students(96.6%) had participated once or twice to animal dissection experiments(eg. fish, frog, shellfish, cuttlefish and chicken). And about half of teachers (57.4$\sim$64.9%) and some students(41.9%) felt ethical conflict in animal dissection. Second, many teachers(81.0%) and students(87.1%) thought that animal dissection was effective method to achieve the goal of biology education, but they needed more consideration on the respect for life in animal dissection experiment. Third, many teachers(88.3%) had students, who objected to animal dissection, participate obligatorily or passively. Fourth, teachers and students thought that audio-visual media such as video(teachers 63.5%, students 39.7%), computer simulations(teachers 31.7%, students 28.1%) and models(teachers 22.2%, students 24.1%) could be effective as alternatives. These findings suggest that animal dissection experiment, although it is needed to achieve the goal of biology education, requires careful consideration on the rights of animal and the respect for life, and alternatives for students who object to animal dissection in biology class.

• Journal of Educational Research in Mathematics
• /
• v.26 no.3
• /
• pp.509-525
• /
• 2016

This study is a follow-up study of the previous research for teacher education(Kim Nam Hee, 2006, 2009, 2013, 2014). This study was conducted with third grade students of the college of education in 2016. In this study, we guided to allow pre-service teachers to develop their teaching research ability and teaching practical skills using the results obtained from the in-service teachers training courses. Processes mainly performed in this study are as follows; learning the theory on Socrates' method, case study for thought experiment activities, instructional simulation using a Socrates' method, class analysis, textbook analysis, peer evaluation, self-assessment. Observing tutorial examples by in-service teachers, pre-service teachers were expanding their limited knowledge and experience. By analyzing the results obtained from this research processes, we checked the points to put more attention in future pre-service teachers education.

• Journal of Korean Philosophical Society
• /
• v.142
• /
• pp.27-50
• /
• 2017

When we lose our memories or when our self-identity becomes blurred, we may feel as if our mind has split into multiple minds. If someone makes another 'me' by copying my body and mind, how should two conscious 'I's change their credences? In this article, we present a new thought experiment that can be called the 'Two Adams Problem'. This thought experiment represents a piece of philosophical inquiry that speculates on the nature of self-consciousness information that 'I am awake now'. On Sunday evening, as soon as Adam falls asleep, the philosopher Roro makes another Adam by copying Adam's original body and mind. They sleep separately in another room. Within a minute, Roro throws a fair coin. If the coin lands heads up Roro wakes just one of the Adams up on Monday. If the coin lands tails up Roro wakes both Adams up. On Monday, at least one of the Adams will wake up. To what degree ought they believe that the outcome of the coin toss is heads? We will argue that the correct answer to this question is 1/2.

• Transactions of Materials Processing
• /
• v.8 no.4
• /
• pp.374-383
• /
• 1999

To determine the flow stress of semi-solid materials, a new combined method has been studied by experimental and analytic technique in the current approach. Using backward extrusion experiment and its numerical analysis, the characterization scheme of semi-solid materials according to the change of initial solid volume fraction has been proposed. Because that solid volume fraction is sensitive to temperature change, it is required to precisely control the temperature setting. Model materials can guarantee the establishment of material characterization technique from the noise due to temperature change. Thus, clay mixed with bonded abrasives was used for experiment and the change of initial solid fraction was copied out through the variation of mixing ratio. Upper bound method was adapted to increase in efficiency of the calculation in numerical analysis and new kinematically admissible velocity field was employed to improve the accuracy of numerical solution. It is thought that the material characterization scheme proposed in this study can be applied to not only semi-solid materials, but also other materials that is difficult to obtain the simple stress state.

• Computers and Concrete
• /
• v.17 no.2
• /
• pp.189-199
• /
• 2016

Chloride penetration is considered as a most crucial factor for the determination of the service life of concrete. A lot of experimental tools for the chloride penetration into concrete have been developed, however, the mechanism was based on only diffusion, although permeability is also main driving forces for the chloride penetration. Permeation reacts on submerged concrete impacting for short to long term durability while capillary suction occurs on only dried concrete for very early time. Furthermore, hydrostatic pressure increases in proportional to measured depth from the surface of water because of the increasing weight of water exerting downward force from above. It is thought, therefore, that the water pressure has a great influence on the chloride penetration and thereby on the service life of marine concrete. In this study, new experiment is designed to examine the effect of water pressure on chloride penetration in concrete quantitatively. As an experiment result, pressure leaded a quick chlorides penetration by a certain depth, while diffusion induced chlorides to penetrate inward slowly. Therefore, it was concluded that chloride should penetrates significantly by water pressure and the phenomena should be accelerated for concrete exposed to deep sea. The research is expected as a framework to define the service life of submerged concrete with water pressure and compute water permeability coefficient of cementitious materials.

• Journal of Oriental Neuropsychiatry
• /
• v.17 no.1
• /
• pp.121-127
• /
• 2006

Objective : As this is a quasi-experimental study by the post-test design for a nonequivalent control group, it was attempted to verify the effect of massage using aroma oil on whether or not the normal vaginal delivery of primiparous mothers. Methods : As for the experimental treatment, it applied the aroma oil massage to the experiment group when the cervical dilatation was $4{\sim}5cm$, and as for the data analysis, it conducted the significance test using the program of SPSS 12K for Windows, with Chi-square test $(X^2)$ and t-test. Results : The experiment group that carried out the aroma massage therapy, was high in the cases of normal vaginal delivery(P<0.05), compared to the control group that did not carry out the aroma massage therapy. Conclusion : The experiment group, which received the aroma massage therapy, had significant difference in the cases of normal vaginal delivery, compared to the control group that did not receive the aroma therapy, thus the aroma massage therapy is thought to be a nursing-intervention plan, which can be usefully applied as to the primiparous mothers aiming at normal vaginal delivery.