• Journal of Microbiology and Biotechnology
• /
• v.16 no.7
• /
• pp.1053-1059
• /
• 2006

The effectiveness of a proteinaceous fibrous material formed during commercial fermentation of soy protein (PFSP) and cysteine addition were evaluated in order to improve on the properties of soy protein-based films. Nine types of films were prepared at pH 7, 9, and 11, with heat treatments at $70^{\circ}C\;and\;90^{\circ}C$ for 30 min, by casting 5% (w/w) PFSP aqueous solution, containing 2.25% (w/w) glycerol, on to polystyrene plates. The tensile strength (TS) of films ranged from 3.88 to 6.87 MPa. The highest puncture strength (PS) was observed with pH 7.0 films prepared from PFSP solution heated at $70^{\circ}C$ (P<0.05). Alkaline pH and temperature caused a decrease in both the TS and PS of the films. The thickness of films ranged from $58\;to\;74{\mu}m$. Water vapor permeabilities of the films decreased with increasing pH and temperature. To produce films from PFSP, pH value of 7.0 to 9.0 and heat treatment of $70^{\circ}C\;to\;90^{\circ}C$ were needed. A soluble nature of PFSP films in water might be useful for preparation of hot water-soluble pouches. Cysteine addition could be necessary to produce films with increased TS and enhanced barrier properties. The combination treatment that provided the best combination of barrier and mechanical properties was the PFSP film prepared at pH 7.0 with addition of 1% cysteine. The films were good oxygen barriers.

• Korean Journal of Materials Research
• /
• v.23 no.2
• /
• pp.135-142
• /
• 2013

The Ti-6Al-4V extra low interstitial (ELI) alloy has been widely used as an orthopedic implant material because of its excellent mechanical properties and biocompatibility. However, it still has many problems, including a high elastic modulus and toxicity of the Al and V elements. Therefore, non-toxic biomaterials with a low elastic modulus need to be developed. A high energy mechanical milling (HEMM) process is introduced to improve the effect of sintering. Rapid sintering of spark plasma sintering (SPS) under pressure was used to make an ultra fine grain of Ti-25 wt.%Nb-7 wt.%Zr-10 wt.%Mo-(10 wt.%CPP) composites with bio-attractive elements for increasing strength. These composites were fabricated by SPS at $1000^{\circ}C$ at 60 MPa using HEMM powders. During the sintering process, $CaTiO_3$, TixOy, and CaO were formed because of the reaction between Ti and CPP. The effects of CPP content on the physical and mechanical properties of the sintered Ti-Nb-Zr-Mo-CPP composites were investigated. The biocompatibility and corrosion resistance of the Ti-Nb-Zr-Mo alloys were improved by the addition of CPP.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.11
• /
• pp.1191-1198
• /
• 2011

The use of a ventricular assist device (VAD) can raise the one-year survival rate without cardiac transplantation from 25% to 52%. However, malfunction of the VAD system causes 6% of VAD patients' deaths, which could possibly be avoided through the development of new VADs in which VAD malfunctions do not affect the patient's heart movement or hemodynamic state. A conventional VAD has an impeller or vane for propelling blood that can allow blood to regurgitate when the propelling force is weaker than the aortic pressure. In this paper, we developed a new pulsatile conduit-shaped VAD that has two valves. This device removes the possibility of blood regurgitation and has a small stationary area even when the pumping force is extremely weak. We estimated the characteristics of the device by measuring the outflow and the pressure of the pump in in-vitro and in-vivo experiments.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.7
• /
• pp.233-240
• /
• 2003

Recently, the world are preparing for new revolution, called as If (Information Technology), NT (Nano-Technology), and BT (Bio-Technology). NT can be applied to various fields such as semiconductor-micro technology. Ultra precision processing is required for NT in the field of mechanical engineering. Recently, together with radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts. Therefore, in this paper, stability of ultra precision cutting unit is investigated, this unit is the kernel unit in ultra precision processing machine. According to alteration of shape and material about hinge, stability investigation is performed. In this paper, hinge shapes of micro stage in UPCU(Ultra Precision Cutting Unit) are designed as two types, where, hinge shapes are composed of round and rectangularity. Elasticity and strength are analyzed about micro stage, according to hinge shapes, by FE analysis. Micro stage in ultra precision processing machine has to keep hinge shape under cutting condition with 3-component force (cutting component, axial component, radial component) and to reduce modification against cutting force. Then we investigated its elasticity and its strength against these conditions. Material of micro stage is generally used to duralumin with small thermal deformation. But, stability of micro stage is investigated, according to elasticity and strength due to various materials, by FE analysis. Where, Used materials are composed of aluminum of low strength and cooper of medium strength and spring steel of high strength. Through this stability investigation, trial and error is reduced in design and manufacture, at the same time, we are accumulated foundation data for unit control.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.05a
• /
• pp.53.1-53.1
• /
• 2011

Bioactive glass powders were synthesized by hydrothermal chemical route by the use of ultrasonic energy irradiation. We used sodalime, calcium nitrate tetra hydrate and di ammonium hydrogen phosphate as the precursor material to synthesize $SiO_2$ rich bio-active glass materials. The $SiO_2$ content was varied in the precursor mixture to 60, 52 and 45 mole%. Dense compacts were obtained by microwave sintering at $1,100^{\circ}C$. Mechanical properties were characterized for the fabricated dense bioactive glasses and were found to be comparable with conventional CaO-$SiO_2$-$Na_2O$-$P_2O_5$ bioactive glass. Detailed biocompatibility evaluation of the glass composition was investigated by in-vitro culture of MG-63 cell and mesenchyme stem cell. Cell adhesion behavior was investigated for both of the cell by one cell morphology for 30, 60 and 90 minutes. Cell proliferation behavior was investigated by culturing both of the cells for 1, 3 and 7 days and was found to be excellent. Both SEM and confocal laser scanning microscopy were used for the investigation. Western blot analysis was performed to evaluate the bimolecular level interaction and extent and rate of specific protein expression. The ability to form biological apatite in physiological condition was observed with simulated body fluid (SBF). In-vivo bone formation behavior was investigated after implanting the materials inside rabbit femur for 1 and 3 month. The bone formation behavior was excellent in all the bioglass compositions, specially the composition with 60% $SiO_2$ content showed most promising trend.

• Journal of Adhesion and Interface
• /
• v.20 no.3
• /
• pp.110-115
• /
• 2019

Graphene oxide has been gathering interests as a way to exfoliate graphene. Since the oxidation group of graphene oxide can hydrogen bond with various functional groups, tremendous efforts have been actively conducted to apply various applications. However, graphene oxide alone cannot substantially possess the mechanical properties required for the practical application. Therefore, in this study, polydopamine, which is a bio-mimetic mussel protein-inspired material, was combined with graphene oxide to form a large-area composite membrane at the liquid-gas interface. In addition, the morphology of the polydopamine-graphene oxide composite thin film was also controlled to obtain a composite membrane having a nano-wrinkle structure. It can be expected to be used in the next generation seawater desalination membranes or carbon composites because it can form mechanically superior and sophisticated nanostructures.

• Journal of Adhesion and Interface
• /
• v.18 no.2
• /
• pp.59-67
• /
• 2017

Recently, integration of parts is accelerating according to the growth of the smart mobile industry. The integration of these parts causes problems of interference phenomena between the parts, and the importance of electromagnetic wave shielding technology to solve this problem is highlighted. Electromagnetic wave shielding technology is implemented so as to reflect or absorb electromagnetic waves, and generally conductive materials are utilized for electromagnetic wave shielding. Transparent shielding technology is required according to recent industrial changes. In this research, we propose transparent the shielding film using imprint technology with conductive composite binder. Utilizing UV polymerized acrylic binder to produce a conductive composite binder. Spherical, plate and stacked silver particles were used for conductivity. The changes of the curing characteristics, conductivity and adhesion were observed according to the structural characteristics of the silver particles. The use of spherical particles was the most efficient in the curing process, and an additional curing system was required to complement the UV-shadowing structure. In the conductivity evaluation, the stacked structure showed excellent characteristics. The adhesion of spherical system was the best. It is evaluated as a result of irregularities on the surface. Ultimately, the patterned film using this showed excellent transparency characteristics.

• Applied Chemistry for Engineering
• /
• v.31 no.2
• /
• pp.115-124
• /
• 2020

Sustainable plastics can be mainly categorized into (1) biodegradable plastics decomposed into water and carbon dioxide after use, and (2) biomass-derived plastics possessing the carbon neutrality by utilizing raw materials converted from atmospheric carbon dioxide to biomass. Recently, biomass-derived engineering plastics (EP) and natural nanofiber-reinforced nanocomposites are emerging as a new direction of the industry. In addition to the eco-friendliness of natural resources, these materials are competitive over petroleum-based plastics in the high value-added plastics market. Polyesters and polycarbonates synthesized from isosorbide and 2,5-furandicarboxylic acid, which are representative biomass-derived monomers, are at the forefront of industrialization due to their higher transparency, mechanical properties, thermal stability, and gas barrier properties. Moreover, isosorbide has potential to be applied to super EP material with continuous service temperature over 150 ℃. In situ polymerization utilizing surface hydrophilicity and multi-functionality of natural nanofibers such as nanocellulose and nanochitin achieves remarkable improvements of mechanical properties with the minimal dose of nanofillers. Biomass-derived tough-plastics covered in this review are expected to replace petroleum-based plastics by satisfying the carbon neutrality required by the environment, the high functionality by the consumer, and the accessibility by the industry.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.11
• /
• pp.2901-2919
• /
• 2012

Recent research in MEMS (Micro-Electro-Mechanical Systems) and wireless communication has enabled tracking of continuous objects, including fires, nuclear explosions and bio-chemical material diffusions. This paper proposes an energy-efficient scheme that detects and tracks different dynamic shapes of a continuous object (i.e., the inner and outer boundaries of a continuous object). EBCO (Efficient Boundary detection and tracking of Continuous Objects in WSNs) exploits the sensing capabilities of sensor nodes by automatically adjusting the sensing range to be either a boundary sensor node or not, instead of communicating to its neighboring sensor nodes because radio communication consumes more energy than adjusting the sensing range. The proposed scheme not only increases the tracking accuracy by choosing the bordering boundary sensor nodes on the phenomenon edge, but it also minimizes the power consumption by having little communication among sensor nodes. The simulation result shows that our proposed scheme minimizes the energy consumption and achieves more precise tracking results than existing approaches.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.899-904
• /
• 2003

Microarrayer makes DNA chip and microarray that contain hundreds to thousands of immobilized DNA probes on surface of a microscope slide. This paper shows the development results for a printing type of microarrayer. It realizes a typical, low-cost and efficient microarrayer for generating low density microarray. The microarrayer is developed by using a robot of three-axes perpendicular type. It is composed of a computer-controlled three-axes robot and a pen tip assembly. The key component of the arrayer is the print-head containing the tips to immobilize cDNA, genomic DNA or similar biological material on glass surface. The robot is designed to automatically collect probes from two 96-well plates with up to 32 tips at the same time. To prove the performance of the developed microarrayer, the general water types of inks such as black, blue and red. The inks are distributed at proper positions of 96 well plates and the three color inks are immobilized on the slide glass under the operation procedure. As the result of the test, it can be shown that it has sufficient performance for the production of low integrated DNA chip consisted of 96 spots within 1 $cm^2$ area.