• Korean Journal of Animal Reproduction
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• v.12 no.1
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• pp.1-10
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• 1988

In order to investigate the spermiogenesis of the Korean Native Jin-do dog, the tissue sampled from the testis and the epididymis of matured dog were conventionally prepared as thin sections. And then these sections were observed under a transmission electron microscope. Based on the development of various permanent organelle and certain transient structures, the spermiogenesis of the dog could be divided into four major phases: Golgi, cap, acrosome and maturation; and these phases had been futher subdivided into seven stages. In the maturatin phase, the karyoplasm has been condensed completely and the nucleus eleongated as the movement of the unclear ring. The equatorial segment has notable waist-form at the late acrosomal stage. In the cross section of the tail, it shows a typicl 9＋9＋2 pattern of the axial fiber bundle condisting of the dense fibers, the inner fibers, and a central pair. The dense fiber number 1, 5, 6, and 9 were larger in diameter than the rest of the dense fibers.

• Composites Research
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• v.26 no.3
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• pp.160-164
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• 2013

In this study, the effect of phosphoric acid (PA) as a fiber spinning aid on the strength increase of polyacrylonitrile (PAN) nano-fibers by using modified mechano-electrospinning technologies has been analyzed. The medium carbonization temperature of $800^{\circ}C$ has been selected for the future economic production of these new materials. The concentration of PAN in dimethyl sulfoxide (DMSO) was fixed as 5 wt%. The weight fraction of PA was selected as being 2%, 4%, 6%, and 8% in comparison to PAN. These solutions have been used to make the nanofibers. The mechano-electrospinning apparatus installed in KRICT was made by our own design. By using this apparatus the continous and highly aligned precursor nano-fibers have been obtained. The bundle of 50 well aligned nano diameter continuous fibers with the diametr of 10 microns with 6 wt% phosphoric acid for addition showed maximum mechanical properties of 1.6 GPa as tensile strength and 300 GPa as Young's modulus. The weight of final product can be increased 19%, which can improve the economical benefits for the application of these new materials.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.7 s.155
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• pp.1025-1033
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• 2006

Kenaf bast can be obtained by decortication of Kenaf stem. Kenaf fibers are much more rough than cotton fiber because they include impurities as pectin, lignin and hemicellulose besides cellulose. The purpose of this research is to investigate the distribution of kenaf fiber length and diameter during the processes of removing impurities. To remove pectin, kenaf bast was retted chemically. A half of the retted kenaf fiber bundle were scoured and bleached. The other half one were treated with $NaClO_2$ solution to remove lignin, and were treated with sodium hydroxide solution to remove hemicellulose. Four kinds of specimens that were obtained for investigating physical characteristics. Length and diameter of 100 fibers on each specimen was measured. The tensile strength of 100 fiber bundles were measured. And also the color values of them were measured with spectrocolorimeter. The length of retted kenaf fiber was 16.97cm. Then it decreased to 11.43cm after bleaching. Kenaf fiber bundles could be finer by chemical processes that remove non-cellulosic materials. The thickness of retted fiber was $132{\mu}m$. And after undergoing the chemical processes to remove non-cellulosic materials, the thickness of kenaf fiber became finer as $73{\mu}m$. Tensile strength of the retted kenaf fiber bundles was 11.37Mpa. The retted kenaf fiber lost their strength as 22.6% by bleaching and as 18.3% by treatment for removing lignin. The retted kenaf fiber showed low whiteness as 56.48 of L*value. After bleaching, the kenaf fibers have creamy white color and their whiteness got 90.02 of L*value. After the treatment for removing hemicellulose, the kenaf fibers also have creamy white color and their whiteness got L* value of 79.02.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.161-164
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• 2006

This paper introduces a preliminary work for the design of a mini-dish cluster system for power general ion. Each mini-dish (typically has a 20 to 30cm in diameter) is designed with a simple parabolic profile, concentrating sun light (after the glass glazing cover to avoid dust deposition on the reflector and facilitate cleaning) onto a centrally located small plane(or concave) mirror which is placed on the bottom side of the transparent glass cover. The mirror with a mini-dish concentrator is designed to focus beam radiation onto a focal point before it enters a bundle of optical fibers connected to a remote receiver for power generation different options are considered In designing a mini-dish concentrator to maximize its effectiveness for the collection and use of solar energy.

• New & Renewable Energy
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• v.2 no.4 s.8
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• pp.39-45
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• 2006

This paper introduces a preliminary work for the design of a mini-dish cluster system for power generation. Each mini-dish [typically has a 20 to 30 cm in diameter] is designed with a simple parabolic profile concentrating sun light [after the glass glazing cover to avoid dust deposition on the reflector and facilitate cleaning] onto a centrally located small plane[or concave] mirror which is placed on the bottom side of a transparent glass cover. The mirror with a mini-dish concentrator is designed to focus beam radiation onto a focal point before it enters a bundle of optical fibers connected to a remote receiver for power generation. Different options are considered in designing a mini-dish concentrator to maximize its effectiveness for the collection and use of solar energy.

• Journal of the Korean Wood Science and Technology
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• v.46 no.3
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• pp.231-240
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• 2018

Bamboo is one of the major biomass resources that have many advantages such as fast growing, easy cultivation, short rotation, and a relatively lower price. In this study, the anatomical characteristics of Moso bamboo (Phyllostachys pubescens) by age from one-year-old to five-year-old were examined by optical and scanning electron microscopy. Also, the crystalline properties such as relative crystallinity and crystallite width were investigated by an X-ray diffraction method. In one-year-old bamboo xylem, a few vascular bundles showed missing bundle sheath in near the intercellular space. Moreover, one-year-old bamboo had the shortest fiber length and the smallest values in vessel diameter, width of vascular bundle, and thickness of inner layer. One-year-old bamboo also showed the smallest values in the crystallinity and crystallite width. Near epidermis samples had longer fiber length and greater vascular bundle spacing than near pith samples. Relative crystallinity and crystallite width near the epidermis were also higher than near the pith. This study revealed significant differences in qualitative and quantitative anatomical characteristics between one-year-old and two-year- or more old Moso bamboos. It is concluded that the structural differences by bamboo age can be used to differentiate the characteristics of juvenile and mature bamboo.

• Journal of Biomedical Engineering Research
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• v.23 no.1
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• pp.27-32
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• 2002

The purpose of this study was to evacuate the effects of the number of tied hollow fibers in a novel membrane oxygenator that satisfied the limiting factor of minimizing the friction loss in the intravascular blood flow Pattern. The membrane oxygenator is a bundle consisted of several hundred ho1low fibers haying the outside diameter of 380 $\mu m$ and the axial jacket length of 600 mm. The eight different variation of tied hollow fibers in a bundle were designed. and the liquid flow pattern was controlled by a pump. The liquid pressure drop was measured by in vitro experiments using water and g1ycero1. Uniform blood flow pattern was observed for each number of tied hollow fibers. Pressure drop was 13-16 mmHg outside of the membrane oxygenator consisting of up to 700 ho1low fibers. More effective contact of liquid with the tied ho1low fibers was observed as a decrease in the number of the tied hollow fibers. and resulted in the enhancement of the friction tractor

• Journal of the Korean Wood Science and Technology
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• v.46 no.1
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• pp.29-37
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• 2018

Bamboo is one of the major biomass resources in the world. To obtain valuable information for effective use of bamboo resources in Korea, the anatomical characteristics of the commercial Korean bamboo species (Phyllostachys pubescens, Phyllostachys nigra, and Phyllostachys bambusoides) were analyzed. The structures in bamboo culm were observed by optical and scanning electron microscopy. Also the crystalline properties as relative crystallinity and crystallite width were measured by an X-ray diffraction method. The three Korean bamboo species had the vascular bundle type I with tylosoid in intercellular space. In the outer part of culm, vascular bundles showed denser spacing than inner part. The fiber length in outer part samples of the three bamboo species showed longer than inner part samples. Furthermore, the fiber length showed a significant difference between inner part and outer part in three bamboo species, showing the longest fiber length in Phyllostachys bambusoides. Phyllostachys pubescens showed the greatest diameter in vessel and parenchyma on cross section. Parenchyma cells in Phyllostachys pubescens and Phyllostachys bambusoides showed similar length and width in both radial and tangential sections. The relative crystallinity and crystallite width in outer part samples of the three bamboo species showed higher values than those in inner part samples, with the greatest values from Phyllostachys bambusoides.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.5
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• pp.1079-1085
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• 2012

Many researchers worldwide have been making a lot of effort to find sustainable clean energy source to replace the current fossil fuels. However, solar energy is considered as the ultimate energy solution to supply the world total power consumption. Light can be used for lighting, heating, wired and wireless communications, etc. Moreover, even light-driven motors which can directly convert optical energy into kinetic energy are studied recently. In this paper, we analyze optical energy delivery through multi-core optical fibers. Our estimation shows that an optical power of 2 kW can be transmitted through a multi-core fiber and an optical power of >10 MW can be transmitted through a bundle of optical fibers with a diameter of several centimeters. It seems competitive compared with the electric power delivery through a copper cable.

• Research in Plant Disease
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• v.10 no.1
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• pp.34-38
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• 2004

The damage of plant growth and alteration of cellular tissues of barley infected by Barley yellow mosaic virus (BaYMV) was explored. The infected plots significantly damaged in all of measured factors by the disease. In severely diseased plant, the viral infection affected on plant growth like as shorten culm length about 25cm, 36％ constrained ratio, comparing to healthy. The yield decreased over 70％ in diseased plots by fewer numbers of spike and kernel per square meter and spike, respectively. BaYMV constructed typical inclusion body like a pinwheel type inside barley leaves, and the infection affected on cellular elongation or growth not cell division in examined three parts as stem, neck of panicle and node, related to dwarfness of infected barley. The stem tissues were most severely affected on cell growth as restrained epidermis cell length in diameter and vascular bundle size. In neck of panicle tissues, distribution and size of tissues of fiber and cortex parts, respectively, showed differences between healthy and infected plants. In node part, healthy plant showed bigger tissue size as 1.5 times than infected plant. Theses results suggest that BaYMV infection could affect on the cell growth not cell division, and which resulted shorten culm length in plant growth and decreased yield, finally.