• The Mathematical Education
• /
• v.55 no.2
• /
• pp.233-249
• /
• 2016

In this study, we extracted the background meaning of the condition that four points lie on a circle, analyzed textbooks critically and proposed the orientation to improve the content in the textbook. As results, the condition has a realistic background meaning which is 'mathematical modeling of finding a fair location'. The condition has a mathematical background meanings which are 'a first complex situation distinguished from two points and three points', 'the condition described in the perspective of side and angle in order to overcome the disadvantages of the perpendicular bisectors context' and 'being possible to transfer more than five points'. However it is difficult to understand the reason why the condition is on four points in the current textbook. In addition, it is difficult to recognize the connectivity of a circumcenter of triangle. To overcome these problems, we proposed five orientations to improve the content in the textbook.

• The Mathematical Education
• /
• v.48 no.3
• /
• pp.287-302
• /
• 2009

This study investigated how 5th grade students found and understood triangle congruence conditions (SSS, SAS, ASA). In particular, this study focused on children's processes of discovering triangle congruence conditions and the obstacles which they encountered in the process of making sense of these conditions. Our data indicates that inquiring the cases in which less than three factors of triangle are given is helpful for children to guess triangle congruence conditions and understand the minimal characteristic of these conditions. And the degree of difficulty of discovering each congruence condition is different. Children discovered SAS condition and ASA condition easily, but it was hard for them to discover and understand that SSS was also a triangle congruence condition because they connected the length of a given side with the use of a scaled ruler not a compass.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2008.11a
• /
• pp.226-230
• /
• 2008

The purpose of this study is to analyse the pedestrian environment of the residential area in residential development. The result of the research are follows; first, the pedestrian environment in the apartment quarter is better than independent residential quarter. second, the pedestrian and the automobile use together the street, because the side walk ist not established from the road where the width is narrow. finally, the condition of side walk paving ist bad, so that the pedestrian environmental level decreased badly

• 한국정보디스플레이학회:학술대회논문집
• /
• 2006.08a
• /
• pp.822-825
• /
• 2006

We propose a transflective In-Plane Switching mode in which patterned retarder is placed only on the reflective area of the upper substrate side. By selecting optic axes of Half Wavelength Plate and Liquid Crystal as 24 and 90 degree with respect to polarizer, condition of low reflectance for visible wavelength range at black state is found.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.1474-1479
• /
• 2004

In electrification of the Honam line, the grounding method of the copper wire shield of 66kV feeder cable was disputed. This paper describes that the review of the proper earthing method(one-side earthing or both-side earthing) under consideration of the site condition and the acceptability of the induction voltage of the shield on the end of the cable.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2002.09a
• /
• pp.1-15
• /
• 2002

In the present paper, the marine reflection seismic survey, the survey using Chirp sonar, the detail topographic survey by narrow multi-beam sounding machine, the sea bottom geological condition survey by side-scan sonar, the sea bottom sampling by core sampler and the positioning by DGPS as the geophysical survey in shallow and transitional region are introduced by placing emphasis on hardware configuration.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.5
• /
• pp.1704-1711
• /
• 2014

Sandy and dusty weather condition often occurs in the high altitude areas of China, which may greatly influence the corona generated radio interference (RI) characteristics of the bundle conductors of 750 kV AC power transmission lines. Corona generated RI of the conductors of the 750 kV AC power transmission lines used in practice is measured by EMI receiver with a coupling circuit and a coupling capacitor connected between the high voltage side and the earth side in fine and sandy and dusty condition. The measuring frequency is 0.5 MHz, and the quasi-peak detection is used. RI excitation function is calculated based on the corona RI current measured by the EMI receiver. Corona generated RI characteristics were analyzed from sand concentration and sand particle size. The test result shows that the corona generated RI excitation function is influenced by the sandy and dusty condition. Corona discharge of the conductors is more serious in sandy and dusty condition with an ultraviolet (UV) detector. Corona generated RI excitation function increases with the increase of sand concentration and also increases with the increase of particle size.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.426-429
• /
• 2003

In this study, phase transformation characteristics of Nitinol shape memory alloy with 54.5wt%Ni-45.5wt%Ti were investigated by varying with annealing treatment and cutting conditions through DSC(differential scanning calorimetry). Annealing treatment conditions were considered as heat treated time of 5 min, 15 min, 30 min, and 45 min, heat treated temperature of 40$0^{\circ}C$, 50$0^{\circ}C$, 5$25^{\circ}C$, 55$0^{\circ}C$, 575$^{\circ}C$, $600^{\circ}C$, $700^{\circ}C$, 80$0^{\circ}C$, and 90$0^{\circ}C$, and environmental condition of heat treatment under vacuum or air. Cutting conditions were considered as no cutting, one side cutting, and two side cutting. Tensile test was also conducted on Nitinol shape memory alloy to investigate thermomechanical characteristics by varying with annealing heat treatment histories. According to the results, annealing treatment and cutting conditions were found to significantly affect on phase transformation and thermomechanical characteristics of Nitinol shape memory alloy.

• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.147-150
• /
• 2002

In general, a single gas flow through a converging nozzle is choked when the pressure communications between the downstream and upstream flowfields are broken by the sonic condition of Mach number, M=1. A similar phenomenon may occur In two streams of different stagnation properties flowing side by side in a converging nozzle. In this case, the limiting condition of M=1 for flow choking is no longer applied to such a compound compressible flow. The compound choking phenomenon can be explained by means of a compound sound wave at the nozzle exit. In order to detail the flow characteristics involved in such a compound choking of the two streams, the two-dimensional, compressible, Wavier-Stokes equations have been solved using a fully implicit finite volume method and compared with the results of the one-dimensional theoretical analysis. The computational and theoretical results show that the compound sound wave can reasonably explain the compound choking phenomenon of the two streams in the convergent flow channel.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.23 no.2
• /
• pp.89-97
• /
• 2003

Experimental model studies were carried out to evaluate the end condition for drilled shafts by applying elastic impact on the top of the shaft, which is one of the various methods using stress waves. Typical impact responses corresponding to the various end conditions including free, fixed, rock-socketed, and soft-bottom with good and poor side contact conditions, were investigated. In order to simulate these renditions, mock-up shaft models made of cement mortar were used. Small-scale laboratory experiments were also performed, and field tests were carried out for the shafts that were socketed into weathered rock. It is found that the rock-socketed condition and depth of penetration into rock ran be identified from the reflection at the interface between the soil and rock in the waveform. The soft bottom rendition can be identified, only when the side contact between shaft and surrounding rock is poor, whereas it cannot be identified when the side contact is good because the waveform is similar to that of fixed end rendition.