• Journal of Pharmaceutical Investigation
• /
• 제37권4호
• /
• pp.243-247
• /
• 2007

Retinoids have many important and diverse functions and particularly, have been widely used as anti-aging agent and for the treatment of acne and psoriasis in cosmetics. However, retinoids have low stability against the air, light, water, oxygen and heat, thus, to stabilize the retinoids in formulations is very critical procedure. In this study, cubic liquid crystalline phase of monoolein was applied to stabilize the retinylpalmitate (RP) and to enhance the transdermal permeation. Cubic liquid crystalline phase significantly enhanced the stability of RP. After 15 days, the content of RP in the cubic formulation was 94.7% while the content of RP in ethanol solution was below 0.5% at room temperature. Although BHT containing crystalline phase showed the slightly increased stability of RP, there were no significant differences in RP stability between with or without antioxidants (ascorbic acid, ${\alpha}$-tocopherol, BHT, BHA) at $40^{\circ}C$. The skin retention of RP in crystalline formulations was approximately $5.3{\sim}6.4$ times greater than that of o/w cream formulation. Incorporation of RP into cubic liquid crystalline phase of monoolein effectively stabilized the RP and worked as excellent topical vehicle for RP. Liquid crystalline phase is considered to be suitable formulation for RP for topical delivery system as a stabilizer and permeation enhancing agent.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.757-760
• /
• 2005

The technology of rapid prototyping (RP) is used for design verification, function test and fabrication of prototype. The current issues in RP are improvement in accuracy and application of various materials. In this paper, a hybrid rapid prototyping system is introduced which can fabricate nano composites using various materials. This hybrid system adopts RP and machining process, so material deposition and removal is performed at the same time in a single station. As examples, micro gears and a composite scaffold were fabricated using photo cured polymer with nano powders such as carbon black and hydroxyapatite. From the micro gear samples the hybrid RP technology showed higher precision than those made by casting or deposition process.

• 한국정밀공학회지
• /
• 제18권3호
• /
• pp.47-52
• /
• 2001

Rapid Prototyping(RP) has been widely applied in designing and developing process of new products. RP can reduce the lead time and expense required to bring a new product form initial concept to production. Among several RP process can dramatically reduce the total build time and be applied for fabrication of large-sized and free form object because it uses in LOM the paper thickness is 0.05∼0.38mm as deposition feature segment. In this study, mechanical properties of pattern with LOM system is studied for optimal design of sand mold casting. The main result is that tensile, compressive strength and pattern size are significantly affected by temperature of hot roll.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 추계학술대회
• /
• pp.1016-1020
• /
• 2003

In this paper, we present a technology of producing anew chaotic micromixer, named Micromixer with Arranged Blocks(MAB), and the experimental result of the mixing performance. Chaotic mixing was successfully achieved by introducing periodic perturbation in the field of the channel flow by means of slanted blocks. The MAB was made by an RP(Rapid Prototyping) technology. We performed flow visualization experiments for the quantification of the mixing performance with the MAB. Lyapunov exponent was measured to be 0.3557 and 0.1305 for the block height 0.8 and 0.2 times the channel width.

• Biomolecules & Therapeutics
• /
• 제22권1호
• /
• pp.73-77
• /
• 2014

The purpose of this study was to examine the effect of stabilization of retinyl palmitate (RP) on its skin permeation and distribution profiles. Skin permeation and distribution study were performed using Franz diffusion cells along with rat dorsal skin, and the effect of drug concentration and the addition of pectin on skin deposition profiles of RP was observed. The skin distribution of RP increased in a concentration dependent manner and the formulations containing 0.5 and 1 mg of pectin demonstrated significantly increased RP distributions in the epidermis. Furthermore, it was found that skin distribution of RP could be further improved by combined use of pectin and ascorbyl palmitate (AP), due largely to their anti-oxidative effect. These results clearly demonstrate that the skin deposition properties of RP can be improved by stabilizing RP with pectin. Therefore, it is strongly suggested that pectin could be used in the pharmaceutical and cosmetic formulations as an efficient stabilizing agent and as skin penetration modulator.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 추계학술대회 논문집
• /
• pp.281-282
• /
• 2008

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.416-421
• /
• 1997

This study presents a way to construct 3D shape in STL format from 2D slice data. Nowadays ahape reconstruct has been done in many ares, the application of this method is important especially in Reverse Engineering which reconstructs original shape from cross-section data. Current RP (Rapid Prototyping) is used not only for the verification of a part designed but also for the production and tooling in more effective way. In RP technology, data should be prepared in STL format. In this paper, the way to make 3D shape data in STL format form 2D slice data is described which can be used to reconstruct an original shape in RP equipment.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1257-1260
• /
• 2003

Rapid Prototyping technology has many advantages such as Rapid Tooling. However, Using the RT technique is limited by the poor surface quality of the RP part. Thus, additional post-machining is required for improving the surface roughness by the sanding, grinding and polishing etc. But, these traditional finishing techniques are time and labor cost consuming. Hence, improving and formulation the finishing technique is inevitably necessary for the RF part. A new post-machining methodology for RP part is presented by the SLS part is used for automobile components in this research. Also, a web based interface tool that user requirements are rapidly ordered for post-machining RP part is developed.

• Journal of Welding and Joining
• /
• 제23권2호
• /
• pp.47-51
• /
• 2005

Rapid Prototyping (RP) technology has helped successfully to reduce time and costs since first emerged in 1986. Recently, RP using functional materials like as metal have been researched. However RP using molten metal and brazing material have been struggling to resolve several drawbacks, such as dimensional inaccuracy, poor surface finish and post finishing because occurring shrinkage and warpage at cooling. So, the purpose of this study is to develop a new RP technique using sheet metal and projection welding for reducing several drawbacks in occurring RP using molten metal. And optimum process variables were determined using desist of experiment(DOE).

• 한국정밀공학회지
• /
• 제16권11호
• /
• pp.62-67
• /
• 1999

The RP&M(Rapid Prototyping and Manufacturing) is the most appropriate technology for the small-lot production system, in which the production cycle is getting shorter owing to various needs from consumers. Recently RP products which are made of plastics, wax, and paper are used to verify the design of samples. But these products cannot be applied to the real mold because the strength enough to be a mold cannot be given by soft materials such as plastics. So RP products are copied to AFR(Al powder Filled Resin) molds or metal molds, which is called the RP&M. In this paper, RP&M is applied to a casting process. A porous casting mold, which is made from ceramic powder and binder, is used for rapid tooling of aluminum shoes molds.