• Resources Recycling
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• v.18 no.3
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• pp.42-48
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• 2009

Since there are $OH^-,\;[SiO_4]^{4-}$ ion of high concentration at early hydration in the system added with activator (NaOH+$Na_2OSiO_2$) in the blast furnace slag, different from cement hydration, hydration progresses fast without induction period and forms reaction rim around the blast furnace slag grain. $0.6{\mu}m$ reaction rim was formed around the blast furnace slag grain from the 1 day of reaction period, and the thickness of reaction rim increases over the reaction time, growing to $1{\mu}m$ on the 28 days. Unreacted blast furnace slag grain deformed from angular shape to the spherical shape. Mole ratio of Ca/Si tends to decrease from inside of blast furnace slag grain to reaction rim. Difference of Ca/Si mole ratio between reaction rim and inside the blast furnace slag grain decreased and generated hydrate was a poor crystalline CSH(I) with Ca/Si mole ratio less than 1.5.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.183-186
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• 2003

Reaction injection molding (RIM) is a widely used process for producing various kinds of complex parts including automobiles, furniture, appliances, and housings. In RIM, products are made from two or more chemical components through mixing, chemical reaction, and molding [1]. Liquid reactants from two supply tanks flow at high pressure into a mix head, where they impinge at high velocity. (omitted)

• Design & Manufacturing
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• v.10 no.3
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• pp.8-13
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• 2016

Despite technological advance, there have been several troubles in photo reaction injection molding (photo RIM) to produce ultra thin light guide panels (LGPs). In this study, micro leakage problem at cavity edge during photo RIM was investigated numerically. In order to obtain optimal processing conditions, we regulated inlet pressure of injected resin at the cavity edge and figured out micro leakage behaviors. At low inlet pressure (less than 100 Pa), though the micro leakage problem was not occurred, another problem, short shot due to not enough driving force, was appeared More than 1,000 Pa of the inlet pressure, injected resin was rapidly leaked through the micro gap at the cavity edge. Finally, we obtained optimal inlet pressure around 600 ~ 1,000 Pa. At this region, injected resin fully filled the cavity without micro leakage behavior. Based on the present study, further comparative investigations with experimental photo RIM should be performed to find optimal processing conditions for produce ultra thin LGPs.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.75-83
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• 2001

RIM(Reaction Injection Molding) is a widely used method to manufacture middle-large size outfit-part for a prototype car. The main advantage of RIM is the capability of manufacturing a small number of prototype parts with less cost and lead time than injection molding which is the most popular method to manufacture plastic parts. Generally, epoxy resin and RTV(Room Temperature Vulcanization) silicon are used as mold materials for RIM, and the selection of mold materials is usually depended upon the industrial environment of manufactures and it decides overall mold making process and part quality. This paper suggests a new mold making process by consolidating the advantages of epoxy resin and RTV silicon based RIM mold to enhance the parts quality while reducing the manufacturing cost and time and shows the competitiveness of the suggested process compared with conventional methods.

• Journal of Powder Materials
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• v.13 no.1 s.54
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• pp.10-17
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• 2006

Model experiment was introduced to obtain the formation of a core/rim structure by only liquid phase reaction in Ti(C, N)-based cermet alloys. Infiltrated Ti(C, N)-Ni, $MO_2C-Ni$, and TaC-Ni cermets were bonded to sandwiched specimen by heat treatment $1450^{\circ}C$ for 5hr. With nitrogen addition, both (Ti, Mo) (C, N) and (Ti, Ta) (C, N) rim structure was nucleated around comer of cuboidal Ti(C, N) core. However, equilibrium shapes of(Ti, Mo) (C, N) and (Ti, Ta) (C, N) rim were different possibly due to the effect of interface energy. The core/rim and rim! binder interfaces were parallel to each other with TaC addition, while rotated to each other with $MO_2C$ addition.

• Bulletin of the Korean Chemical Society
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• v.17 no.6
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• pp.502-506
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• 1996

Several ester group-containing calix[4]arenes were synthesized by the reaction of calix[4]arene and various acyl chlorides. Two or four ethyl succinyl units could be introduced into the calix[4]arene lower rim depending on the reaction conditions. But the mixture of three and four ethyl malonyl substituted calix[4]arenes were obtained and only three ethyl oxalyl units were introduced at the lower rim of calix[4]arene. Interestingly when calix[4]arene was treated with ethyl oxalyl chloride in the presence of aluminum chloride, two ethyl oxalyl units were introduced at the upper rim of calix[4]arene. The conformation of those ester-containing calix[4]arenes was presented based on the 1H and 13C NMR spectra.

• Honam Mathematical Journal
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• v.14 no.1
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• pp.67-84
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• 1992

• Journal of the Korean Society for Precision Engineering
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• v.33 no.1
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• pp.31-35
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• 2016

For reaction injection molding (RIM) polyurethane was mixed in the mixing head by impingement mixing, injected into the mold, and cured quickly, as soon as the mold is filled. The shape of the nozzle in the mixing head is critical to improve the quality of polyurethane. To achieve homogeneous mixing, an intensive turbulence energy in the mixing nozzle is essential. In this study, a mixing nozzle for RIM was designed, and mixing efficiency was investigated based on experiment. Experiments were conducted with different combinations of nozzle tips and exit diameter to measure the mixing efficiency by measuring jet force and investigating mixing image with high speed camera. Jet force increased gradually and reaches steady state conditions. The jet force depended on shape of nozzle tip and outlet sizes. These results suggest that optimized nozzle configurations are necessary for high efficiency mixing with RIM.

• Bulletin of the Korean Chemical Society
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• v.16 no.2
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• pp.153-157
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• 1995

Calix[6]arenes are selectively dialkylated at the lower rim and further functionalized by the aminomethylation and Claisen Rearrangement reactions. Dialkylation was conducted by the reaction of calix[6]arene and alkyl halides such as benzyl bromide, allyl bromide, ethyl bromoacetate, propyl bromide, and methyl iodide under the carefully controlled reaction conditions. Aminomethylation was carried out with the treatment of disubstituted calix[6]arene and secondary amine in the presence of formaldehyde. Claisen rearrangement reaction of the O-diallylcalix[6]arene produced the p-diallylcalix[6]arene.

• Bulletin of the Korean Chemical Society
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• v.17 no.6
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• pp.525-528
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• 1996

Seven cali[4]arenes, having two different substituents in AAAB or AABB pattern at the upper rim of calix were synthesized by fragmentation condensation reaction of p-substituted phenol trimer (AAA) with 2,6-bishydroxymethylated 4-substituted phenol (B) or that of dimer (AA) with 2,2'-bishydroxymethylated dimer (BB). An equimolar mixture of the coupling components (trimer and monomer or dimer and dimer) was refluxed in dioxane in the presence of TiCl4to afford calix[4]arene 6 and 7 in 15-38% yield. The structure of calix[4]arenes was confirmed by elemental analysis and the 1H/13C NMR spectroscopy.