Needle-punched aramid nonwoven fabrics were manufactured with a focus on the fiber fineness, fiber length, and needle punching density to improve the absorption and distribution of impact energy, and their physical properties, structure, and low-velocity impact behavior were investigated. In addition, thermal-bonded aramid nonwoven fabrics were manufactured with different mixing ratios of the binder fibers (LM-PET), and their impact resistance properties were analyzed. The tensile strength of the aramid nonwoven fabrics were observed to increase with an increase in the needle punching density. In comparison with woven fabrics of the same weight, the nonwoven fabrics exhibited higher energy absorption capability. This can be attributed to the higher deformability of the nonwoven fabrics that arises from an easily disordered fiber network of the mechanically entangled structure when under impact. Most of the impact energy was dissipated by frictional sliding and deformation of the fibers without significant fiber fracture. Mixing the binder fibers improved the impact absorption due to physical entanglement caused by the needle punching and adhesion between the fibers and the web in the binder fibers.

Since the 1980s, paper relics, including funeral odes, have been excavated during the process of urbanization, including land development and change of burial sites. However, these relics are extremely difficult to study because they are seriously damaged and may not be in their original shape. For safe conservation and restoration of such excavated paper relics, it is important to accurately characterize their fibers through appropriate scientific analyses. This study details optical analyses using stereoscopic microscopy, fluorescent microscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FT-IR), conducted on the paper fibers of seven funeral odes excavated from the burial site of Gwon Goeng (1494-1563). They were excavated from Gagoli, Pungcheonmyeon, and Andongsi in Gyeongsangbugdo, Korea, in March 2017. The investigation revealed that these materials are extensively damaged by pollution, hardening, and molds. Microscopic analysis showed that all the paper fibers of the funeral odes had a transparent membrane, suffered dislocation, and had cross-markings that are distinctive characteristics of paper mulberry bast fibers. SEM-EDS analysis of the foreign substances found between the fibers showed that these fibers comprise 14 different kinds of elements such as carbon, oxygen, calcium, sodium, and iron. The purpose of this study is to report on the kind of paper materials used in funeral odes during the middle Joseon period.

Barrier properties of packaging materials can be enhanced by controlling their microstructure and/or blending them with nanofillers such as cellulose nanocrystals (CNCs). CNCs have attracted considerable attention for use in reinforcing composite materials because of their exceptionally high specific strength and modulus, low density, chemical tunability, renewable nature, and relatively low cost. In this study, barrier films were prepared by incorporating CNCs into a poly(vinyl alcohol-co-ethylene) (EVOH) matrix. The CNCs prepared by acid hydrolysis of microcrystalline cellulose were ~348 nm long and 20 nm in diameter, with aspect ratios of 16. The nanocomposites were prepared by incorporating 1, 2, and 3 wt.% CNCs into an EVOH matrix using solution casting. Turbiscan analysis and contact angle measurements show that the EVOH/CNC composite films possessed interfacial interactions and good dispersion properties. As a result, these composite films may not show any decrease in their transparency. In particular, the oxygen transmission rate in the composite films significantly decreased from $3.2cm^3/(m^2{\cdot}day)$ to $1.3cm^3/(m^2{\cdot}day)$ when the CNC was added, indicating that the EVOH/CNC nanocomposite films can be used as barrier packaging materials.

As the use of high-performance and highly functional industrial fibers has rapidly increased, the amount of the resulting fiber waste has also risen. The purpose of this study was to develop methods for recycling aramid/cotton-blend fabric and characterize its use in flame retardant work clothes. For this purpose, we investigated its properties through Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), and performed a comparative analysis of the mechanical properties of the fabric with a KES-FB system. The recycled fabric retained the properties of both the cotton and aramid fibers. When compared with pure aramid fabric, the recycled aramid/cotton-blend fabric was more flexible, had a higher $Q_{max}$ and thermal conductance, and a similar level of water vapor permeability. These results indicate that the recycled aramid/cotton fabric is comfortable to wear. This study also established a database that can be referenced for the utilization of recycled, aramid/cotton-blend fabrics in flame retardant work clothes.

In this study, pure tone and speech hearing tests were conducted on 60 participants working in shoe-manufacturing factories in Busan in order to examine the effects of exposure to mixed organic solvents and noise on their hearing abilities. The control group was selected from the general public. The shoe-manufacturing workers and the participants selected from the general public represented the exposed and unexposed group, respectively. We observed statistically significant differences in the uncomfortable levels and speech recognition threshold levels between the participants of the exposed and unexposed groups. These observations indicate that the discomfort index increases significantly due to continuous exposure to noise and mixed organic solvents. Furthermore, it was observed that exposure to noise and organic solvents had the same effect on the hearing abilities of the left and right ears. The results of this study were similar to those of earlier studies that showed that hearing loss caused by noise occurs mostly in the high frequency range (3,000-6,000 Hz), and changes most significantly at 4,000 Hz. Categorizing the participants into grades of hearing loss revealed that 13.3% of the participants of the exposed group exhibited a certain level of hearing loss. This was higher by approximately 8% than that observed in the unexposed group (5%), which can be attributed to long-term exposure of the exposed group to mixed organic solvents and noise.

In order to develop the high impact resistant composites with high mechanical properties, carbon fiber composites of polycarbonate matrix having high toughness were studied. Carbon fiber reinforced polycarbonate (carbon/polycarbonate) composites were manufactured by a hot press molding under different temperature ($270-285^{\circ}C$) and pressure($1.5-5ton/in^2$) conditions. The mechanical properties of flexural, interlaminar shear strength, impact energy and morphological features of the carbon/polycarbonate composites were investigated with the molding conditions. The carbon/polycarbonate composites manufactured at $280^{\circ}C$ and $3.5ton/in^2$ for 3 min. was found to have maximum flexural strength of 820 MPa and interlaminar shear strength of 55 MPa due to the effects of high matrix impregnation and good fiber alignment. On the other hand, the maximum impact resistance of the composite appeared at low flexural strength and interlaminar shear strength.

As the substitute of synthetic black hair coloring materials, we focused on benzopyran natural colorants as known as a pleochroism dyes which forms coordination complexes with metal ion. We selected sappan wood(brazilin) and logwood(hematoxyilin) to represent benzopyran-based colorants. Ferrous sulfate and the extract of alder tree or tannic acid were used for mordanting. Wool was applied as the reference for hair dyeing to improve the color properties. By using both of metallic- and bio-mordants, we obtained the dyed hair of deep black color and high color strength with less than 8% of the surface reflectance. Light colorfastness of the dyed hair was relatively good and the rating 4-5 was obtained up to 100 hrs. And the rating to washing of the dyed hair was maintained 5 up to 30 cycles for the evaluation of colorfastness.

In this study, poly(lactic acid) (PLA) nanofibers with sheath-core structure was prepared by coaxial electrospinning. The morphology of PLA sheath-core nanofibers was characterized using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The PLA nanofibers with sheath-core structure was successfully fabricated by coaxial electrospinning, and the loading of model drug was controlled by solution feed ratio. In addition, the dual drug release of PLA nanofibers was evaluated in the physiological media. From the results, the cumulative release rate of model drug in sheath part was higher than that in core part. The PLA sheath-core nanofibers has a great potential for drug delivery system and scaffolds for tissue engineering.

Poly(2-cyano-1,4-phenylene/3,4'-oxydianline terephthalamide) (CNO-Aramid) copolymers and poly(2-cyano-1,4-phenylene terephthalamide) (CNPPTA) were synthesized by low temperature polycondensation reaction of 2-cyano-1,4-phenylene diamine and 3,4'-oxydianiline with terephthaloyl chloride. Structural characterization and thermal stability of CNO-Aramid copolymers and CNPPTA were investigated by FT-IR spectroscopy and thermogravimetric analyzer (TGA). TGA results show that CNO-Aramid copolymer and CNPPTA have excellent thermal stability at high temperature. It was found that CNO-Aramid copolymers with higher ether group contents had better solubility in polar organic solvents such as NMP, DMAc, DMSO, and DMF than CNPPTA.