• Korean Journal of Child Studies
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• v.26 no.6
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• pp.161-171
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• 2005

In Experiment 1, 4- and 5-year-olds were shown either continuous(i.e., pizza) or discontinuous Stimuli(i.e., biscuit) by the experimenter. After a proportion(e.g., 2/8, 4/8, or 6/8) was removed, children were asked to remove an equivalent proportion. Whereas 4-year-olds proportional reasoning was correct only when they shared the same stimulus with the experimenter, 5-year-olds reasoned correctly regardless whether or not they shared the stimulus with the experimenter. In Experiment 2, where the discontinuous stimulus was changed, 4-year-olds also made correct proportional reasoning even when their stimulus was different from the experimenter's. Contrary to other studies, quantity didn't affect children's proportional reasoning except the proportion 1/4, where problems with discontinuous quantity were solved more successfully than problems with continuous quantity.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.6
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• pp.44-51
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• 1997

Crinding of stainless steel, aluminium alloy, copper alloy, and titanium alloy are difficult to obtain high quality finish, because they have the mechanical properties such as low hardness, high toughness. The low hardness and the high toughness result in the loading of wheel and the poor surface finish. In order to perform the grinding operations for these sorts of materials easily, the discontinuous grinding wheel wiht multi-porous grooves has been newly developed. The multi-porous grooves inthe discontinuous grinding wheel were formed during grinding wheel manufacturing process. In this paper, discontinuous grinding wheels having intermittent ratio 0.66, 0.81 and number of grooves 18,32 have been manufactured and grinding surface characteristics of these grinding wheels for SUS304 have been analyzed. Discontinuous grinding temperature according to intermittent ratiohas been also estimated by simulation. The discontinuous grinding wheels increase the grinding performance considerably. It is desirable to use the discontinuous grinding wheel in grinding the materials with high efficiency and accuracy.

• Korean Journal of Cognitive Science
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• v.24 no.3
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• pp.271-300
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• 2013

Human and animals are born with an intuitive ability to determine approximate numerosity. This ability is termed approximate number sense (hereafter, number sense). Evolutionarily, number sense is thought to be an essential ability for hunting, gathering and survival. According to previous research, children with mathematical learning disability have impaired number sense. On the other hand, individuals with more accurate number sense have higher mathematical achievement. These results support the hypothesis that number sense provides a basis for the development of mathematical cognition. Recently, researchers have been examining whether number sense training can lead to enhancement in mathematical achievement and changes in brain activity in relation to mathematical problem solving. Numerosity which basically represents discontinuous quantity is expected to be closely related to continuous quantity such as representations of space and time. A theory of magnitude (ATOM) states that processing of number, space and time is based on a common magnitude system in the posterior parietal cortex, especially the intraparietal sulcus. The present paper introduces current literature and future directions for the study of the common magnitude system.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.3
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• pp.314-319
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• 2005

To compare two different schemes, continuous scheme (CS) and discontinuous scheme (DCS), of once-weekly ovum pick up (OPU) with ultrasound-guided follicular puncture technique, Holstein heifers were randomly divided into two groups of five. After characterization of their two normal estrous cycles, the heifers were subjected to consecutive 20 weeks of once-weekly OPU under two schemes: the CS (one week interval between continuous OPU, total 100 OPU sessions performed) and the DCS (OPU fixed to the day 3 and day 10 of each estrus). Then, the status of ovaries and artificial insemination results were observed. On oocyte yield, the total number of punctured follicles using DCS was lower than that using CS, but the mean numbers of punctured follicles and recovered oocytes per session were higher in DCS than CS group. So the total number of recovered oocytes was similar in both groups. There were also no differences in the quality of recovered oocytes, nor in the developmental ability of oocytes fertilized in vitro between groups. The heifers in the DCS group showed regular estrous cycles with stable estrous signs through the periods of before, during, and after OPU, while those in CS group showed longer estrous cycles and less estrous signs during and/or after OPU compared with before period. Furthermore, the mean number of inseminations required for obtaining pregnancy after completion of the experiments was lower in DCS than CS group. The research demonstrates that similar quantity and quality oocytes can be achieved, and the side effects on donors are lower in DCS that needs fewer OPUs than CS group, and DCS is superior to CS.

• Journal of the Korean GEO-environmental Society
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• v.10 no.3
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• pp.21-28
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• 2009

As the natural aggregates such as sand and clay are getting exhausted, the quantity of utilizing geosynthetics is being increased in the solid waste landfill. Especially, the waste landfills have been constructed at the gorge in the mountainous area and reclaimed land from the sea in the Korean Peninsula. Those areas are not favorable for construction of waste landfill in geotechnical engineering aspect. In this study, the frictional characteristics of geosynthetics that used in the waste landfill were estimated. Then, the studies of the behavior of geosynthetics and stability of LDCRS (Leachate Detection, Collection, and Removal System) of side slope were conducted in the waste landfill by means of the pilot test, and numerical analysis. Geocomposite which is combined type or separated type is influenced on the strain itself, and also implicated in the stress and strain of geomembrane at the lower layer. The strain on the combined type of geocomposite is about 50% smaller than that of the separated type at the side slope. The lateral displacement and settlement of top at the slope with the separated type are three times greater than that of the combined type. In the numerical analysis, discontinuous plans in between ground and geosynthetic, geosynthetic and geosynthetic, goesynthetic and waste have been modeled with the interface element. The results gave a good agreement with the field large-scale model test. The relative displacements of geosynthetics were also investigated and hence the interface modeling of liner system is appropriate for analysis of geosynthetics liner system in the waste landfill.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.3
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• pp.133-147
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• 2005

Various types of ray-tracing methods are used to predict the quantity measures of radiation illumination, the uniformity of illumination, radiation performance of LCD BLU(Hack-Light Unit). The uniformity of radiation illumination is one of the most important design factor of BLU and is usually controlled by the diffusive-ink pattern printed on the bottom of light-guide panel of BLU. Therefore it is desirable to produce an improved (ideally, the optimal) ink pattern to achieve the best uniformity of radiation illumination. In this paper, we applied the Welder-Mead simplex-search method among various direct search method to compute the optimal ink pattern. Direct search methods are widely used to optimize the functions which are often highly nonlinear, unpredictably discontinuous, and nondifferentiable, The ink-pattern controlling the uniformity of radiation illumination is one type of these functions. In this paper, we found that simplex search methods are well suited to computing the optimal diffusive-ink pattern. In extensive numerical testing, we have found the simplex search method to be reasonably efficient and reliable at computing the optimal diffusive-ink pattern. The result also suggests that optimization can improve the functionality of simulation tools which are used to design LCD BLU.