• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.33 no.4
• /
• pp.139-144
• /
• 2023

Stone papers made of inorganic filler and plastic polymer do not use pulp, which is the main raw material of existing papers, so they contribute to the preservation of nature and can be used as more eco-friendly materials when they have biodegradability. Since most stone papers are manufactured by hot extrusion, the amount of ceramic fillers and related physical properties are limited to control manufacturing workability. In this study, the stone paper composition was prepared in a liquid form using solvents, so that there was little limitation on the amount of ceramic filler added and it was also easy to add additives to control biodegradability. They were fabricated from eco-friendly raw materials using waste oyster shells as an inorganic filler and (recyclable) PVC materials as an organic binder. After making a solution using common solvents for PVC, inorganic filler and cellulose to impart biodegradability were mixed and processed into sheets to prepare solvent-based stone papers, and their paper properties were evaluated.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.5
• /
• pp.3351-3356
• /
• 2014

Recently, Importance of studying based on biomass materials have increased due to the concern about plastic waste problems. Cellulose acetate butyrate (CAB) is a potential alternative to petroleum-based plastics because of its biodegradable property. Poly(ethylene-co-isosorbide terephthalate) (PEIT) is bio-based plastic, produced by isosorbide monomer. In this study, CAB/PEIT blends were prepared by solution blending to improve thermal stability of CAB. CAB and PEIT were dissolved in chloroform, and then precipitated in ethanol. To evaluate the compatibility of CAB/PEIT blends, the morphology and glass transition behaviors were analyzed by FE-SEM and DMA, respectively. TGA results revealed the improved thermal stabilities of the PEIT-rich and 50:50 compositions. No new or changed crystal structures were observed in the XRD result. Finally, CAB/PEIT solution blends showed good compatibility in overall compositions.

• Archives of Plastic Surgery
• /
• v.36 no.3
• /
• pp.247-253
• /
• 2009

Purpose: Hydroxyapatite(HA) has been widely used due to its chemical similarity to bone and good biocompatibility. HA is composed of macropores and micropores. Too much irregularities of the micropores are ineffective against the adhesion and proliferation of osteoblast. Many efforts have been tried to overcome these drawbacks. HA crystal coating on the irregular surface of HA scaffold, crystallized HA, is one of the method to improve cell adhesion. Meanwhile, the collagen has been incorporated with HA to create composite scaffold that chemically resembles the natural extracellular matrix components of bone. The authors proposed to examine the effect of collagen - coated crystallized HA on the adhesion and proliferation of osteoblast. Method: HA powder containing $10{\mu}m$ pore size was manufactured as 1 cm pellet size. For the making crystallized HA, 0.1 M EDTA solution was used to dissolve HA powder and heated $100^{\circ}C$ for 48 hours. Next, the crystallized HA pellets were coated with collagen (0.1, 0.5, and 1%). The osteoblasts were seeded into HA pellets and incubated for the various times (1, 5, and 9 days). After the indicating days, methylthiazol tetrazolium (MTT) assay was performed for cell proliferation and alkaline phosphatase (ALP) activty was measured for bone formation. Result: In SEM study, the surface of crystallized HA pellet was more regular than HA pellet. MTT assay showed that the proliferation of osteoblasts increased in a collagen dose - dependent and time - dependent manner and had a maximum effect at 1% collagen concentration. ALP activity also increased in a collagen dose - dependent manner and had a highest effect at 1% collagen concentration. Conclusion: These data showed that crystallization and collagen coating of HA was effective for osteoblast proliferation and ALP activity. Therefore, our results suggest that crystallized - HA scaffold with collagen coating is may be a good strategy for tissue engineering application for bone formation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.159-159
• /
• 2009

We characterize a flexible self-assembled liquid crystal display (LCD) fabricated from a polyimide (PI) alignment layer with polydimethylsiloxane pixel walls. Ion beam (IB) irradiation aligned LC molecules in the PI layer and bonded two flexible plastic substrates in a one-step assembly of the pixel walls. X-ray photoelectron spectroscopic analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy provided chemical and physical evidence for the formation of stable chemical bonds between the PI layer and the PDMS pixel walls in addition to the important maintenance of a uniform 6 um gap between the two substrates without the use of any epoxy resins or other polymers.

• Transactions of Materials Processing
• /
• v.14 no.4 s.76
• /
• pp.360-367
• /
• 2005

The injection-molded plastic parts have many surface defects: warpage, weldline, flowmark, zetting, scratching, shading and so on. As weldline was one of the major surface defects in the case of desktop monitor, warpage and surface shrinkage are the bigger problems of LCD monitor in the pursuit of light weight and thinner thickness of parts. Some measures to improve these defects were introduced in this paper. Based on these, the laboratory work to find out the optimum processing conditions and to get the best parts was repeated injection moulding try-out after reflecting these improvements. The defects of warpage and surface shrinkage was significantly improved after the improvements in the case of the 20.1 inch even if in the 15 and 17inch case the warpage size was a lttle over the allowed specification because of not taking the measure for parts design within the allowable limits from the required specification in the cause of cost down.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.10a
• /
• pp.339-346
• /
• 2003

Molecular dynamic simulations of nano indentation on single-crystal silicon (100) surface were performed using diamond indentor. Silicon substrate and diamond indentor were modeled diamond structure with Tersoff potential model. Phase transformation of silicon, incipient plastic deformation, change of incident temperature distribution are investigated through the change of potential energy distribution, displacement-load diagram, the change of kinetic energy distribution and displacements of silicon atoms. Phase transformation is highly localized and consists of a high-density region surrounding the tip. Axial load linearly increased according to the indenting depth. Number of atoms with high kinetic energy increased at the interface between substrate and indentor tip.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.623-624
• /
• 2005

Micro injection molding is a branch of micro system technology and has been under development for the mass manufacture of micro parts. Enhanced technological products like micro optical devices are entering the market. This paper presents fundamental research on the injection molding technique in micro fabrication. In order to successful manufacturing of micro plastic parts, it is necessary to research for development of micro-injection machine, machining of micro mold, decision of optimum injection conditions and the research for polymer material. Therefore in this study, in order to machining of micro mold, a mold core with microscopic V-shaped groove was tooled by ultra-precise tooling machine. The transcription experiments with a polymer, PMMA resin on the surface of core with Ni plating were carried out and surface profile of injected parts was measured with AFM.

• Journal of the Korean Institute of Navigation
• /
• v.16 no.2
• /
• pp.21-27
• /
• 1992

Shortening the lasing wavelength(particularly below infrared ; the visible region) of laser diodes is very attractive because it can provide a wide range of applications in the fields of optical information, measurement, sensor, the development of medical instrument, and optical communication through plastic fibers. According to the recent researches on the field, InGaAsP/GaAs was suggested as a material for red-light laser. In this study, in order to grow InGaAsP/GaAs epitaxial layer on InGaAsP/GaAs by LPE, we used GaP and InP two phase solution technique for 670nm and 780 nm region, respectively. Through the X-ray diffraction measurement for the epitaxial layer grown from the experiments, we found that the lattice mismatch of $In_{0.46}Ga_{0.54}As_{0.07}P_{0.93}$/GaAs and $In_{0.19}Ga_{0.81}As_{0.62}P_{0.38}$/GaAs was about +0.3% and +0.1%, respectively.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.14 no.3
• /
• pp.103-109
• /
• 2005

Since fretting fatigue damage accumulation occurs over relatively small volumes, the role of the microstructure is quite significant in fretting fatigue analysis. The heterogeneity of discrete grains and their crystallographic orientation can be accounted for using continuum crystallographic cyclic plasticity models. Such a constitutive law used in parametric studies of contact conditions may ultimately result in more thorough understanding of realistic fretting fatigue processes. The primary focus of this study is to explore the influence of microstructure as well as the magnitude of the normal force and tangential force amplitude during the fretting fatigue process. Fretting maps representing cyclic plastic strain behaviors are also developed to shed light on the cyclic deformation mechanisms.

• Journal of Mechanical Science and Technology
• /
• v.19 no.3
• /
• pp.802-810
• /
• 2005

Deformations of single crystals were studied using finite element analysis to investigate the localized modes and the orientation dependence of plastic deformation observed in single crystals. Investigation of mechanical properties of single crystals is closely related with the understanding of deformation processes in single crystals. Localized bands such as shear and kink were studied and the material and geometric characteristics that influence the formation of such localized bands were investigated. Orientation dependence of material behavior in NiAl single crystals was studied by rotating slip directions from 'hard' orientation. The maximum nominal compressed stress in NiAl single crystals was widely ranged depending on the misalignment from 'hard' orientation. As the compression axis was set closer to 'hard' orientation, the maximum nominal compressed stress was rapidly increased and made <100> slips difficult to activate. Therefore, non-<100> slips will be activated instead of <100> slips for 'hard' orientation.