• Journal of Hydrogen and New Energy
• /
• v.25 no.2
• /
• pp.131-138
• /
• 2014

Highly conductive bipolar plate for polymer electrolyte membrane fuel cell (PEMFC) was prepared using phenol novolac-type epoxy/graphite powder (GP)/carbon fiber filament (CFF) composite, and a rubber-modified epoxy resin was introduced in order to give elasticity to the bipolar plate graphite fiber (GF) was incorporated in order to improve electrical conductivity. To find out the cure condition of the mixture of novolac-type and rubber-modified epoxies, differential scanning calorimetry (DSC) was carried out and their data were introduced to Kissinger equation. And tensile and flexural tests were carried out using universal testing machine (UTM) and the surface morphology of the fractured specimen and the interfacial bonding between epoxy matrix and CFF or GF were observed by a scanning electron microscopy (SEM).

• Textile Coloration and Finishing
• /
• v.6 no.1
• /
• pp.44-48
• /
• 1994

Cellulose triacetate(CTA) liquid crystal solutions obtained via dissolution of CTA in solvent mixture of triflucroacetic acid and methylene chloride were spun and saponified in various chemicals. Among chemicals, methanol/sodium hydroxide mixture endowed highest tenacity as well as modulus to regenerated cellulosic fiber and the fiber thereof showed Cell I or Cell IV morphology, or mixed morphology of Cell I and IV.

• Journal of Food Hygiene and Safety
• /
• v.7 no.4
• /
• pp.153-163
• /
• 1992

Dietary fiber imparts both mutritional and functional properties to foods. This review deals with (1) the classification of dietary fiber, (2) the plant cell wall models, (3) the relations between structure and physicochemical and functional properties of dietary fiber and (4) the applications of dietary fiber in foods. Dietary fiber can be classified in terms of source, plant function, solubility, charge and topology. Plant cell wall models are presented to provide information on the interconnections of dietary fiber components which determines the content of soluble and insoluble dietary fiber content. In reality, physicochemical and functional properties of dietary fiber originate factors such as chemical constituents , charge, branching degree, conformation and etc. Dietary fibers possess a variety of functional properties in food systems, which thus make them useful in food application. In particular, rheology and gelation of water-soluble gums or hydrocolloids are discussed for their effects on food quality. A guideline s also listed for the gum selection to meet the best product requirements.

• Proceedings of the Korean Fiber Society Conference
• /
• 2003.10b
• /
• pp.34-37
• /
• 2003

The development and improvement of advanced fuel cell systems is a major topic of current research, since fuel cells are considerably more efficient than other energy converters$^1$. In proton exchange membrane fuel cell and direct methanol fuel cell the polymer membrane represents a key component. The membrane materials fulfill complex requirements. It has to combine electrochemical stability, workability, high ionic conductivity, low permeation of the reactants (methanol etc.) (omitted)

• Applied Microscopy
• /
• v.44 no.2
• /
• pp.61-67
• /
• 2014

Layered structures of fiber cell wall of Korean red pine (Pinus densiflora) were investigated by confocal reflection microscopy (CRM). CRM micrographs revealed detailed structures of the fiber cell wall such as S1, S2, and S3 layers as well as transition layers (S12 and S23 layers), which are present between the S1, S2, and S3 layers. Microfibril angle (MFA) measurement was possible for the S2 and S3 layer in the cell wall. The experimental results suggest that CRM is a versatile microscopic method for investigation of layered structures and MFA measurement in individual sub layer of the tracheid cell wall.

• Microbiology and Biotechnology Letters
• /
• v.13 no.3
• /
• pp.209-212
• /
• 1985

The cell density and packing characteristics of Escherichia coli immobilized in a dual hollow fiber bioreactor consisting of outer silicone membrane for oxygen transport and three inner isotropic polypropylene hollow fibers for substrate transport were investigated. The cells have grown forming the layer like animal tissue in a nearly 100％ packing density. The dry biomass density was 550g/liter of void volume for cell growth, which was the highest among the biomass densities ever reported.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.9
• /
• pp.2770-2781
• /
• 1996

Longitudinal shear modulus of continuous fiber reinforced 2-phase composites is predicted by theoretical and numerical analysis methods. In this paper, circular, hexagonal and rectangular shapes of reinforced fiber are considered using unit cell concept. And fiber array is regular rectangular and hexagonal fiber arrangement. Longitudinal shear modulus is a function of fiber distribution pattern and fiber volume change. It is found that the rectangular array has a higher longitudinal shear modulus than the hexagonal one. Also, the rectangular fiber shape in lower fiber volume fraction and the circular fiber shape in higher fiber volume fraction show the higher longitudinal shear modulus. And it has been found that the theoretical and numerical predictions of the longitudinal shear modulus give a good agreement with the experimental data at lower fiber volume fraction. Both the distance and stress transfer between the fibers are discussed as the major determing factors.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.46 no.2
• /
• pp.35-45
• /
• 2014

Confocal Reflection Microscopy (CRM) was applied to investigate external fibrillation of different types of fibers such as Kajaani reference fiber, Whatman filter fiber, thermomechanical pulp (TMP), and recycled TMP fiber. It was confirmed that the CRM images are created from surface structures of the fiber cell wall. Confocal Laser Scanning Microscopy (CLSM) captured overall shape of the fiber, but minute details of the surface of the fiber were missed. CRM captured the minute details of the fiber surface. From the CRM and CLSM images, it was observed that the CRM images mainly appeared on the fiber surfaces. External fibrillation of the fiber occurs at the fiber surface, not inside the cell wall. Thus, it was concluded that investigation on the external fibrillation of the fiber was possible by utilizing CRM images. A direct qualtitative and quantitative method for analysis of external fibrillation of fiber was demonstrated by utilizing surface area to volume ratio, volume fraction, and roughness calculated from 3-dimensional images reconstructed from stacks of CRM images from the different fibers.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.42 no.1
• /
• pp.7-12
• /
• 2010

Morphological characteristics of hemp fiber were investigated using a light microscope in order to provide fundamental data for the use of hemp as a papermaking law material. Phloem of hemp is composed of cortical parenchyma cells and bast fiber with thick walls while xylem is composed of vessel, wood fiber and ray parenchyma cells. Also there are solitary pore and radial pore multiple which exist in diffuse porous pattern. Ray cells consist of uniseriate rays and thin walled ray parenchyma cells. Wood fibers are composed of three types: a large diameter fiber with longer length; a large diameter fiber with shorter length; a small diameter fiber with medium length. Vessel elements are composed of: a medium length one; a longer length one; the one whose both end walls have ligules or tails. Parenchyma cells in xylem and pit parenchyma cells have completely different size and shape. For bast fiber, the average length is about 4.4 mm and the width is about $30.5\;{\mu}m$; for vessel element, $600.0\;{\mu}m$ in length and $493.6\;{\mu}m$ in width; for wood fiber, $1000\;{\mu}m$ and $38.9\;{\mu}m$; for parenchyma cell, $50\;{\mu}m$ and $26.4\;{\mu}m$.

• Computers and Concrete
• /
• v.8 no.5
• /
• pp.525-539
• /
• 2011

This paper describes the development of a fiber reinforced concrete (FRC) unit cell for analyzing concrete structures by executing a multiscale analysis procedure using the theory of homogenization. This was achieved through solving a periodic unit cell problem of the material in order to evaluate its macroscopic properties. Our research describes the creation of an FRC unit cell through the use of concrete paste generic information e.g. the percentage of aggregates, their distribution, and the percentage of fibers in the concrete. The algorithm presented manipulates the percentage and distribution of these aggregates along with fiber weight to create a finite element unit cell model of the FRC which can be used in a multiscale analysis of concrete structures.