• Journal of the Korean Ceramic Society
• /
• v.31 no.6
• /
• pp.660-670
• /
• 1994

Transparent, crack-free dried gel monoliths with a composition of LiZr1.5Si2P2O12.5 have been synthesized by the low temperature polymerization of the Sol-Gel technique using metal alkoxides as starting materials. After initial reaction (20~40 min), each metal alkoxide closely paralleled each other during the hydrolysis reactions. The safe drying conditions of gels with no creaks the control of the shrinkage rate. The gels converted into the glass by heat treatment at 75$0^{\circ}C$. FTIR data indicated that the gels were phase separated into silicarich and phosphate-rich regions with the lithium. XRD results showed the formation of crystalline LiH2PO4. The gels dried at 15$0^{\circ}C$ or fired at 75$0^{\circ}C$ contained the residual water. The high ionic conductivity at room temperature for these gels was attributed to the motion of protons.

• The Korean Journal of Ceramics
• /
• v.6 no.1
• /
• pp.37-42
• /
• 2000

To reduce shrinkage and the possibility of fracture during ambient pressure drying, it is of great importance to increase the strength and stiffness of the wet gels. In this paper is presented the strengthening and stiffening of wet silica gels prepared from sodium silicate (water glass) as well as properties of the corresponding xerogels. By washing gels containing different initial silica contents in water solutions at elevated pH, a maximum in shear modulus of ~4 MPa was obtained. The maximum stiffness enabled xerogels with bulk density of 0.28g/$\textrm{cm}^3$ to be made regardless of silica content and washing conditions. However, by aging the wet gels in a solution providing fresh monomers to the gel network, a shear modulus of 20 MPa was obtained after 27h. By this method monolithic xerogels with a density down to ~0.2g/$\textrm{cm}^3$ was prepared. The results are compared to alkoxide based gels.

• International Journal of Concrete Structures and Materials
• /
• v.3 no.2
• /
• pp.97-101
• /
• 2009

It has been known that acid-resistant concretes on the liquid glass basis have high porosity (up to 18${\sim}$20%), low strength and insufficient water resistance. Therefore they can not be used as materials for load-bearing structural elements. Significant increasing of silicate matrix strength and density was carried out by incorporation of special liquid organic alkali-soluble silicate additives, which block of superficial pores and reduces concrete shrinkage deformation. It was demonstrated that introduction of tetrafurfuryloxisilane additive sharply increases strength, durability and shock resistance of silicate polymer concrete in aggressive media. This effect is attributable to hardening of contacts between silicate binder gel globes and modification of alkaline component owing to "inoculation" of the furan radical. The optimal concrete composition with the increased strength, chemical resistance in the aggressive environments, density and crack resistance was obtained.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.6 no.3
• /
• pp.136-145
• /
• 2006

Two major processing technologies of GaAs HBT and pHEMT have been released in production at Win Semiconductors corp. to address the strong demands of power amplifiers and switches for both handset and WLAN communications markets. Excellent performance with low processing cost and die shrinkage features is reported from the manufactured MMICs. With the stringent tighter manufacturing quality control WIN has successfully become one of the major pure open foundry house to serve the communication industries. The advancing of both technologies to include E/D-pHEMTs and BiHEMTs likes for multifunctional integration of PA, LNA, switch and logics is also highlighted.

• Fibers and Polymers
• /
• v.2 no.1
• /
• pp.152-156
• /
• 2001

Three different silicone polymer systems, such as aminofunctional, epoxyfunctional, and hydrophilic epoxyfunctional silicone polymers, were applied onto plasma pretreated wool fabric to improve the dimensional properties. The results showed that the plasma pretreatment modified the cuticle surface of the wool fiber and increased the reactivity of wool fabric toward silicone polymers. Felting shrinkage of plasma and silicone treated wool fabric was decreased with different level depending on the applied polymer system. Fabric tear strength and hand were adversely affected by plasma treatment, but these properties were favorably restored on polymer application. Therefore, it has been concluded that the combination of plasma and silicone treatments can achieve the improved dimensional stability, and better performance properties of wool fabric. The surface smoothness appearances of treated fabrics were measured using a new evaluation system, which showed good correspondence with the results of KES-FB4 surface tester.

• Laser Solutions
• /
• v.2 no.3
• /
• pp.32-41
• /
• 1999

This study is about Jig used in wiring when we make Probecard and Large Scale Intergrated Electronic Circuit. The most universal wiring method is molding with Bond. Polymer film is punched down and adhesives is applied after wiring. Due to shrinkage and modification many problems still have happened in the process of molding. To solve these problems, ceramic plate was introduced in the study. Using Laser, an experiment of microhole treatment on ceramic plate was proceeded. Laser energy, assistance gas, and special features by purity degree were analyzed with the 35W low capacity YAG-Laser. In the condition of energy 0.08J, frequency 20Hz and interval time 200$mutextrm{s}$, about 70${\mu}{\textrm}{m}$ microhole was adequate for the Probecard Jig. In the purity experiment of ceramic materials, high purity ceramic met with good result for microhole. But the price is too high. The shape and size of holes machined combustion gas $O_2$ were better than those in $N_2$ and Ar, the inert gas.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2000.04a
• /
• pp.47-52
• /
• 2000

Recently, it is very necessary the development of the manufacturing techniques for high strength concrete(HSC) for the large-scale size and good quality of civil structure. But, the manufacture and quality control of HSC of which shrinkage, heat of hydration and workability at construction filed are considered, is very difficult due to its low water-cement ratio and high quantity of unit cement content. In the present study, we tried to know and assess the influences of chemical and physical properties of cement on the material properties of HSC. We analyzed basic properties of 4 kinds of cement whose chemical and physical properties are different each other through various tests such as chemical analysis and mortal test. Also, we performed the assessment of the material properties of HSC for each dement by the test for the conditions of same mix design and similar compressive strength. From the results in the study, the assessment of the important quality factors of cement influencing the properties of HSC may be utilized to quality control of applied cement to manufacture the HSC of high quality.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.10a
• /
• pp.433-438
• /
• 2004

The rapid machining of prototypes plays an important role in product process. Rapid Prototyping(RP) is the widespread technology to produce prototype. But, it have many problems such as shrinkage, deformation and formation occurred by hardening of resin and stair shaping, On the contrary, high speed machining(HSM) technology has many advantages such as good quality, low cost and rapid machining time. Moreover, it is possible to use the material of original product. This paper presents manufacture of trial product by HSM and optimization of machining condition for high productivity in the view of manufacturing time and average error. For example, propeller is machined by the surface machining of thin surface parts. Experiments are designed of machining conditions by Latin Square method and machining condition is optimized and selected by ANOVA

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.05a
• /
• pp.245-246
• /
• 2012

The analysis of microstructure is essential to understand the material behavior such as shrinkage, strength, and permeability. In this study, three different easy-to-apply specimen preparation methods for the mercury intrusion analysis were chosen, and their effectiveness in removing pore water and thus impeding further hydration was evaluated. As a result, it was found that the direct freeze-drying was the most effective among the three methods.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.10 s.175
• /
• pp.99-106
• /
• 2005

This paper presents manufacture of mock-up by HSM and optimization of machining condition for high productivity in the view of manufacturing time and accuracy. The rapid machining of prototypes plays an important role in building mock-up. Rapid Prototyping(RP) is a technology to make prototype. But, it have many problems such as shrinkage. deformation and formation occurred by hardening of resin and stair shaping. On the contrary, high speed machining(HSM) technology has many advantages such as good quality, low cost and rapid machining time. HSM and RP is compared for machining efficiency. Experiments are designed by Latin Square Method and machining condition is optimized and selected by ANOVA. For example, propeller is machined by the surface machining of thin surface parts.