• Journal of Power System Engineering
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• v.5 no.4
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• pp.74-81
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• 2001

The infiltration behavior of molten Al-alloy, microstructures, hardness, and the interfacial reactions of $SiC_p/Al$ composites fabricated by the pressureless infiltration technique were investigated. It was made clear that both the weight fraction of SiC reinforcement and additive Mg content considerably influenced on the infiltration behavior of the molten Al-alloy matrix. Complete infiltration of molten Al-alloy achieved under the conditions that weight fraction of SiC content is more than 30wt%, and additive Mg content is more than 9wt%. Interfacial region of Al-alloy matrix and SiC reinforcement phase, $Mg_2Si$ was formed by the reaction between Mg and SiC. Another reaction product AlN was also formed by the reaction between Al-alloy matrix and gas atmosphere nitrogen.

• Analytical Science and Technology
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• v.8 no.4
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• pp.865-868
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• 1995

The method of matrix-assisted laser desorption ionization mass spectrometry has been used to solve some bioanalytical problems, which is difficult to analyse by general methods. For the selection of proper laser wavelength and matrices, eight matriees was used with laser wavelength of 226 and 355nm. The result shows that with wavelength of 355nm better results could be obtained with most of the matrices. The molecular weight of eytochrome C, which was seperated by gel electrophoresis and electro-blotted onto NC membrane is determined by MALDI. The accuracy is better than 0.1%, which is much higher than that of SDS-PAGE. Protein mixture extracted from crude peanut oil is directly determined by MALDI. The molecuiar weight of its three components are determined, and the result also demonstrated that these proteins are in free manner. As proteins arc in 2S bond, with the traditional method, SDS-PAGE, it is not able to decide whether protein exists in combination mode or in free manner. In the technique of two phase aquesous solution, which is used for separating biomaterials, water soluble polymers stained with dyes are used in this technique. By the use of MALDI the number or the dye molecules react with the polymer PEG molecule are determined, and that is difficult to determined by other methods.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.89-92
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• 1995

For the development of lilght weight cement concrete with high durability, this study used perlite and paper sludge ash by the light weight material, and polypropylene fiber by the reinforcment, and poly-acrylic ester emulsion by the matrix improvement. According to the increasing mixture ratio of fiber and use of polymer, the light weight polypropylene fiber reinforced polymer cement ratio of fiber and use of polymer, the light weight polypropylene fiber reinforced polymer cement concrete were showed high resistance for frost damage.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.480-507
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• 2003

A rapid and efficient method for analyzing the nonionic surfactants and silicone polymers, which control the shape and characteristics of cosmetic products and give influence on product quality, has been developed using Matrix-Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI- TOF IMS). The MALDI-TOF/MS could easily and effectively determine the molecular weight distribution and monomer units of nonionic surfactants. As a result, creating a library of mass spectrum data of surfactants used in cosmetic products using MALDI-TOF/MS and analyzing surfactants extracted from the products may become a useful method for detailed structural characterization of the surfactants. Furthermore, the MALDI-TOF/MS analysis was effective in obtaining the spectrum of silicone polymers from which the molecular weight distribution could be determined. The repetition units and structural data could also be obtained through molecular mass peaks. Additionally, the monomer ratio and terminal groups as properties of silicone copolymers could be determined

• Journal of KSNVE
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• v.10 no.1
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• pp.97-106
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• 2000

The dynamic behavior of crankshaft-bearing system in scroll compressor has been investigated using the combined methodologies of finite elements and transfer matrices. The finite element formulation is proposed including the field element for a shaft section and the point element at balancer weight locations, bearing locations, etc., whereas the conventional method is used with the elements. The Houbolt method is used to consider the time march for the integration of the system equations. The linear stiffness and damping coefficients are calculated for a finite cylindrical fluid-film bearing by solving the Reynolds equation, using finite difference method. The orbital response of crankshaft supported on the linear bearing model is obtained, considering balancer weights of motor rotor. And, the steady state displacement of crankshaft are compared with a variation in balancer weight. The loci of crankshaft at bearing locations are composed of the synchronous whirl component and the non-synchronous whirl component.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.455-458
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• 2003

An optimal control approach to robust control design is proposed in this study for rigid robotic systems under the unknown load and the other uncertainties. The uncertainties are quadratically bounded for some positive definite matrix. Iterative method to find the matrix is shown. Simulations arc made for a weight-lifting operation of a two-link manipulator and the robust control performance of robotic systems by the proposed algorithm is remarkable.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.176-182
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• 2003

An optimal control approach to robust control design is proposed in this study for rigid robotic systems under the unknown load and the other uncertainties. The uncertainties are quadratically bounded for some positive definite matrix. Iterative method to find the matrix is shown. Simulations are made for a weight-lifting operation of a two-link manipulator and the robust control performance of robotic systems by the proposed algorithm is remarkable.

• Journal of Animal Science and Technology
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• v.62 no.4
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• pp.533-542
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• 2020

The objective of this study was to observe the interactions between salt-soluble proteins extracted from beef and elephant foot yam (Amorphophallus campanulatus) flour in heat-induced gel matrix development. The effect of salt concentration; 0.5%, 1.0%, 1.5%, and 2.0% in weight/weight basis (w/w), during protein extraction on pH, salt-soluble protein concentration and myofibril fractions of beef extract was determined firstly, and no significant effect was found. The beef salt-soluble proteins extracted using salt solution at different concentrations were then added with elephant foot yam flour at 5%, 10%, and 15% w/w, gelatinized at 90℃ for 20 min, and cooled down at 4℃ for 12 h. The interactions between beef salt-soluble proteins and elephant foot yam flour resulted in an improved gel strength (p < 0.01) and the addition level of elephant foot yam flour affected the pH, instrumental color, moisture, crude protein, and ash content significantly. The addition of elephant foot yam flour also reduced the size of the pores in the gel matrix as shown by scanning electron microscope (SEM) photographs. These suggest that elephant foot yam flour well interacts with beef salt-soluble proteins to form gel matrix.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.663-667
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• 2005

Surface modified carbon nanotubes were applied into the epoxy composites to investigate its tribological property. Carbon nanotubes reinforced epoxy composites were fabricated by casting. Effects to the tribological property of loading concentrations and types of surface modification of carbon nanotubes were investigated under sliding condition using linear reciprocal sliding wear tester. The results show that the small amount of carbon nanotubes into the epoxy exhibited lower weight loss than the pure epoxy. It is concluded that the effect of an enormous aspect ratio of carbon nanotubes surface area which wider than conventional fillers that react as interface for stress transfer. As increased the contents of carbon nanotubes, the weight loss from the wear test was reduced. And the surface modified carbon nanotubes show better tribological property than as produced carbon nanotubes. It is due that a surface modification of carbon nanotubes increases the interfacial bonding between carbon nanotubes and epoxy matrix through chemical bonding. Changes in worn surface morphology are also observed by optical microscope and SEM for investigating wear behaviors. Carbon nanotubes in the epoxy matrix near the surface are exposed, because it becomes the lubricating working film on the worn surface. It reduces the friction and results in the lower surface roughness morphology in the epoxy matrix as increasing the contents of the carbon nanotubes.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.116-123
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• 1990

Synthesis and characterization of photosensitive orthonaphthoquinonediazide-sulfonyl derivatives were studied. These photoactive compounds underwent a UV induced transformation to the base-soluble photoproduct. The photoresists were prepared using these photoactive compounds with low molecular weight m-cresol novolacs as matrix resin. And photosensitive characteristics of the photoresists were studied. 3, 4, 5-Trihydroxy-benzophenone with bulky resonance structure increased the sensitivity and the solubility rate of the exposed region. The mixture of PAC and matrix resin having 3:8 weight ratio had the moderate rate of dissolution in the developer. The photoresist using these conditions showed the best snsitivity and contrast under the fixed conditions.