• Journal of Korean Elementary Science Education
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• v.28 no.2
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• pp.154-160
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• 2009

Correlational reasoning is used to analyze results from an experiment and create meaningful relationships among variables. Although there were many recognition development studies, not a single study found the optimal period for the development of logical thinking. Therefore, the purpose of this study is to find the optimal period for students whose logic for variable controlling and correlational reasoning are poor. This study made a logic program treatment subject for students between the 4th and 8th grade whose recognition in reasoning has not been developed in general in order to find the optimal period for their development. The variable-controlling reasoning was performed the program of voice survey and sugared-water melting in subsection survey and sugared-water melting in subsection. And, the correlation reasoning was performed the program of rat's size and tail color, treatment, and effect. As a result of research, students, who were not formed variable controlling and correlational reasoning, could be known to be enhanced through learning, but to fail to be formed the qualitative change like the cognitive development. In other words, the optimal period couldn't be found that is grown the formation of students, who are not formed the variable controlling and correlational reasoning, through learning. It is expected that this research can contribute to the improvement of students' cognitive level and there would be more active researches in different fields to improve the cognitive level.

• Economic and Environmental Geology
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• v.27 no.2
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• pp.171-180
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• 1994

Several ultramafic bodies and ultramafic origin talc deposits are distributed in Chungnam province near the contact zone with Ogchun fold belt They occur as discontinued belt form with northeast trending, and most of them are more or less sepentinized. Major, trace, and rare earth elements analyses were made of the ultramafics from the study area to constrain their origin and genetic relationships. Compared to the primitive mantle estimates of privious workers, the correlations defined by the studied rock samples indicate similar Ni but very lower $Al_{2}O_{3}$, CaO and $TiO_{2}$ contents. It is inferred that source material of the studied rocks might be residual mantle which had undergone a large degree of partial melting event. The REE patterns show relatively flat to enriched in LREE (chondrite normalized La/Yb and Sm/Yb ratios are 1.1-5.2 and 1.2-1.6). Several alternative explaination are possible for LREE enrichment patterns in the studied ultramafic rocks such as 1) enrichment due to late stage alteration, 2) enriched pre-melting composition, and 3) mixing of two components. Based on the result, the LREE enrichment characteristic of the studied rocks might be result from the mixture of two geochemically distinct components; one is depleted residual mantle and the other component which determine the abundances of incompatible elements and responsible for the LREE enrichment.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.489-494
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• 1997

A comparative transient analyses were performed for oxide and nitride cores or a large (3000 MWt), pool-type, liquid-metal-cooled reactor (LMR). The study was focused on three representative accident initiators with failure to scram : the unprotected loss-of-flow (ULOF), the unprotected transient overpower (UTOP), and the unprotected fast transient overpower (UFTOP). The margins to fuel melting and sodium boiling have been evaluated for these representative transients. The results show that there is an increase in safety margin with nitride core which maintains the physical dimensions of the oxide core.

• Proceedings of the Korean Fiber Society Conference
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• 1997.04a
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• pp.328-332
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• 1997

Hot stretching focused on the improvement of properties of poly(L-lactic acid) fiber. Some aliphatic polyesters are biodegradable under microbial attack and the new unique applications are expected. Generally, these materials have a somewhat low melting temperature and low mechanical properties compared with the aromatic polyesters. In this study, melt-spinning of poly(L-lactic acid) was conducted. We investigated effects of the stretching and the molecular orientation of aliphatic polyester fibers on the change of fine-structure. Glass transition temperature, molecular orientation and crystallinity increased according to the increase of stretching ratio.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1737-1746
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• 1991

본 연구에서는 저온의 순수물 속의 등온 수직원기둥에 의해 야기되는 열전달 특성을 구명함에 있어서 짧은 원기둥 범주에 속하는 종횡비 0.5인 얼음 원기둥을 이용 하여 실험적으로 열전달 특성을 구명하였다. 그리고 전 유동장을 가시화 하였으며, 얼음의 융해율로써 누셀트(Nusselt)수를 측정하여 기존의 결과들과 비교검토하였다.

• Journal of Welding and Joining
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• v.14 no.3
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• pp.93-104
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• 1996

This study evaluated relative hot cracking susceptibility of commercial aluminum alloy welds, and then suggested possible mechanisms operated in the weld fusion zone and in the heat affected zone based on the observed cracking morphologies, fractography and microstructural features. The fusion zone solidification cracking was found to be mainly due to a microsegregation of Cu, Si, and Mg in grain boundaries, while liquation cracking in the HAZ was by the incipient melting of the segregated grain boundaries and the consitutional liquation of large aging precipitates and intermetallic compounds in the partially melted zone adjacent to the fusion line which experienced a rapid thermal excursion during welding.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.157-162
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• 2000

The object is design an optimal injection position on the Monitor Cover. In this paper, the defined injection position are three types, which simulate in melting temperature, molding temperature and weld line in variation. We obtained a result from simulation and descried the result related injection pressure with injection position.

• 한국기계연구소 소보
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• s.19
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• pp.23-30
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• 1989

Heat transfer phenomena of solidification process of the phase change material within cylindrical can is studied experimentally. N-Eicosane paraffin wax is used for phase change material and its melting temperature is 309.8 K. In order to achieve higher heat transfer rate of latent heat storage apparatus, fins in made of copper are used in the cylindrical can. If there are fins in cylindrical can, we can know that the inward latent heat energy in paraffin can be effectively transfered to cooling water than if finless.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.217-219
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• 2005

In the conventional GMAW of 9% Ni steel, Inconel wire has been employed. The major problem of the Inconel GMAW is that arc stability and fluidity of weld pool is poor. Lack of fusion and convex weld bead is liable to occur in case of 9% Ni steel because of low melting point of Inconel wire. In this study the effect of shielding gases on the Inconel 625 GMA weldability was investigated.

• Journal of the Korean Applied Science and Technology
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• v.27 no.4
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• pp.482-486
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• 2010

In this study, 2-(Nitroimino)imidazoline was prepared by the reaction of nitroguanidine with ethylenediamine in the presence of water at $65^{\circ}C$. The product was identified by using various analytical tools such as melting point, elemental analyzer, IR spectrophotometer, mass spectrometer and TLC. This compound can be used as intermediate for prepareing pesticide-imidacloprid packing and cosmetics preservative.