• Journal of Sericultural and Entomological Science
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• v.38 no.1
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• pp.25-30
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• 1996

The adsorption mechanism of Chromium(VI) uptake in silk fibroin fibers was discussed. The adsorption equilbrium of Chromium(VI) is significantly influenced by the initial adsorption rate and it showed 52% of the equilibrium uptake. The Chromium(VI) uptake by silk fibroin in increased with the acidic range of pH, which react upon Chromium(VI) oxidations. The enthalpy change in the Chromium(VI) on the temperatures, $\Delta$H, was found to be 39.7 KJ.mol-1, It means that the Chromium(VI) adsorption proceeds via a certain complex chemical reaction and the Chromium complex was found to be coordinated with carbonyl group of amides from the result of infrared spectra. The chroming of silk fibroin fibers in moderated in the conditions of 5$0^{\circ}C$, pH 2.4, and 3 hours, which prevent from the loss of physical properties. The equilibrium adsorption is attained at 5 X 10-3M of Chromium(VI) solutions.

• Journal of the Korean Geosynthetics Society
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• v.16 no.1
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• pp.73-83
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• 2017

Laboratory and in-situ tests were conducted to evaluate the cone factors for the layers with low plasticity containing a lot of silty and sand soils from the west coast (Incheon, Hwaseong and Gunsan areas) and its applicability was evaluated based on these results. The cone factors were evaluated from 19 to 23 based on unconfined compression strengths (qu), from 13 to 13.8 based on simple CU strengths and from 11.6 to 13.1 based on field vane strengths, respectively. The unconfined compression strengths of undisturbed silty soil samples with low plasticity were considerably underestimated due to the change of in-situ residual effective stress during sampling. Half of unconfined compression strength (qu/2) based cone factors of silty soils with low plasticity fluctuated and were approximately 1.8 times higher than simple CU based values of these soils. When evaluating cone factors of these soils, it should be judged overall on the physical properties such as the grain size distribution and soil plasticity and on the fluctuation of the corrected cone resistance and the sleeve friction due to the distribution of sandseam in the ground including pore pressure parameter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.10
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• pp.642-647
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• 2015

The perovskite solid solutions of the $Sr_{1-x}Mg_xFe{^{3+}}_{1-{\tau}}Fe{^{4+}}_{\tau}O_{3-y}$ system (x=0.0, 0.1, 0.2, and 0.3) were synthesized in $N_2$ at $1,150^{\circ}C$. X-ray powder diffraction study assured that all the four samples had cubic symmetries(SM-0: $3.865{\AA}$, SM-1: $3.849{\AA}$, SM-2: $3.833{\AA}$, and SM-3: $3.820{\AA}$) and that the lattice volumes decreased steadily from $57.7{\AA}^3$ to $55.7{\AA}^3$ with x values. The nonstoichiometric chemical formulas were determined by Mohr salt analysis and with the increase of x values the amounts of $Fe^{4+}$ ion and oxygen were decreased simultaneously. Thermal analysis showed that SM-0 started to lose its oxygen at $450^{\circ}C$ and SM-1, Sm-2, and SM-3 began to lose their oxygen at around $350{\sim}400^{\circ}C$. SM-0 showed almost reversible weight change in the cooling process. All the samples exhibited semiconducting behaviors in the temperature range of $10{\sim}400^{\circ}C$. Conductivities of the 4 samples were decreased in the order of SM-0, SM-1, SM-2, and SM-3 at constant temperature. The activation energies of the conductions were in the range of 0.176 eV~0.244 eV.

• Earthquakes and Structures
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• v.22 no.1
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• pp.1-13
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• 2022

When a building suffers damages under moderate to severe loading condition, its physical properties such as damping and stiffness parameters will change. There are different practical methods besides various numerical procedures that have successfully detected a range of these changes. Almost all the previous proposed methods used to work with translational components of mode shapes, probably because extracting these components is more common in vibrational tests. This study set out to investigate the influence of using both rotational and translational components of mode shapes, in detecting damages in 3-D steel structures elements. Three different sets of measured components of mode shapes are examined: translational, rotational, and also rotational/translational components in all joints. In order to validate our assumptions two different steel frames with three damage scenarios are considered. An iterative model updating program is developed in the MATLAB software that uses the OpenSees as its finite element analysis engine. Extensive analysis shows that employing rotational components results in more precise prediction of damage location and its intensity. Since measuring rotational components of mode shapes still is not very convenient, modal dynamic expansion technique is applied to generate rotational components from measured translational ones. The findings indicated that the developed model updating program is really efficient in damage detection even with generated data and considering noise effects. Moreover, methods which use rotational components of mode shapes can predict damage's location and its intensity more precisely than the ones which only work with translational data.

• Applied Biological Chemistry
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• v.33 no.4
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• pp.301-306
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• 1990

The Physical and chemical properties or dry acorn starch(DS), detannined acorn starch (DTS) and defatted and detannined acorn starch(Drn) were investigated. Ail acorn starch sample, observed by a scanning electron microscope, showed a hemispherical shape ud its size was about $5{\sim}10{\mu}m$ in diameter. It had a little change on the pasting temperature of DS, DTS and DFTS but peak viscosity of DTS was somewhat higher than that of n. Flow behavior of gelatinized starch pastes showed a pseudoplastic behavior and flow behavior index was lower than unit. The consistency coefficient showed concentraion and temperature dependency. The activation energies of DS, DTS and DFTS were $2.09{\sim}3.58Kcal/g\;{\cdot}\;mol and time dependent characteristic of acorn starch samples showed thixotrpic behavior.

• Journal of Sensor Science and Technology
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• v.26 no.2
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• pp.96-100
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• 2017

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been extensively studied as the active material in ammonia gas sensor because of its fast response time, high conductivity and environmental stability. It is well known that a post annealing process for organic devices based on PEDOT:PSS significantly increases the device performance. In this study, we propose the solvent annealing of PEDOT:PSS and investigated its effects. As a results, post solvent annealing on PEDOT:PSS lead to the surface chemical and physical properties change. These changes result in improved conductivity of the PEDOT:PSS. In additional, ammonia sensitivity of solvent annealed PEDOT:PSS become higher than pristine polymer film. The enhancement is mainly caused by the depletion of gas barrier PSS and structural re-forming PEDOT networks. We believe that the post solvent annealing is a promising method to achieve highly sensitivity PEDOT:PSS films for applications in efficient, low-cost and flexible ammonia gas sensor.

• Korean journal of food and cookery science
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• v.15 no.1
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• pp.50-54
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• 1999

The persimmon puree was hydrolyzed with commercial polysaccharide hydrolyzing enzymes, Viscozyme and Celluclast and jam was prepared with the enzyme treated persimmon juice by addition of pectin. The textural characteristics of the jam were studied for the effects of pectin addition and storage temperature. When the persimmon jam was prepared with the enzyme treated juice with addition of pectin(2.2∼3.0%), the hardness of the go] was stabilized at the addition level of more than 2.8% as measured by %sag. The hardness, cohesiveness, adhesiveness, and gumminess were also significantly increased as the amount of pectin addition increased, whereas the cohesiveness and elasticity did not change significantly. The gel prepared with the puree hydrolyzed with Celluclast generally showed higher hardness, gumminess and adhesiveness and less cohesiveness and elasticity than those treated with Viscozyme. Higher temperature (17$^{\circ}C$) caused a significant decrease in most of the textural properties except elasticity. Results of sensory test showed the orange colors was much improved by the Celluclast treatment, while other characteristics such as total acceptability and texture were not significantly different.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.7
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• pp.50-55
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• 2018

The important thing in extrusion technology is the design and production of molds. Appropriate design of the molds is essential for achieving the desired extrusion of molds at the same time to maximize the life of the molds and increase their efficiency. The extrusion temperature and extrusion speed are the main parameters at the time of extrusion. Different extrusion conditions should be added depending on the extrusion ratio, physical properties of the material, and type of extrusion. In this study, the extrusion process of various 6xxx series aluminum cast alloys for high speed train interior or exterior parts were investigated. The extruded die design was performed for the 6063, 6061, 6N01, 6005, 5083 and 6060 alloy profiles and an extrusion test was conducted. In addition, the extrusion conditions, such as extrusion pressure following as the billet temperature, extrusion temperature, and materials change, were analyzed. Although the 6063 aluminum alloy can be extruded at the lowest temperature and pressure, the 6061 alloy can be extruded at the highest temperature and pressure. From these results, the successful extruded products were manufactured from these established conditions.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.537-542
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• 2011

Magnesium hydroxide as a non-halogen flame retardant has increasing attention due to its non-toxicity, high decomposition temperature and smoke suppressant ability during combustion. For the application of magnesium hydroxide retardant to the textile by soaking and coating method, the prerequisite for the coating is a small particle size, stable dispersion, and adhesion to the textile. The dispersion of $Mg(OH)_2$ particles and stability of the coating was checked by monitoring the change of transmittance and backscattering by varying the types of dispersion agents, binder, solvent, and $Mg(OH)_2$ source, and their compositions in the coating. The $Mg(OH)_2$ dispersion coating was applied to PET(poly(ethylene terephthalate)) non-woven textile. The physical properties are characterized by surface morphology, amount of coating, particle dispersion, and adhesion test. The flame retardant $Mg(OH)_2$ coated textile has been compared by limited oxygen index(LOI) and thermal gravimetry and differential scanning calorimetry(TG-DSC). It was found that phosphorous additive may give synergistic effect on $Mg(OH)_2$ flame retardant coating to make the flame retardant PET non-woven textile.

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.413-418
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• 2001

We investigated change of crystal structure, surface morphology and crystal orientation of the electrodeposited film from dispersed $SiO_2$ suspensions (colloidal silica) copper sulfate bath and arse corrosion potentials and physical specific properties. As addition of colloidal silica in copper electrolytic hath, the crystal Particles on filial was fined-down, made uniform and account of particles were increased. Hardness of copper electrodeposited film ascended about 15% and (111), (200) and (311) plane of X-ray diffraction patterns were almost swept away, so preferred orientation chanced from (111) to (110) plane. Also, corrosion potential of electrodeposited copper film was noble with colloidal silica addition.