• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.149-157
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• 2002

This paper is to investigate collapse mechanisms of CFRP(Carbon Fiber Reinforced Plastics)composite tubes and to evaluate collapse characteristics on the change of interlaiminar number and ply orientation angle of outer under static and impact axial compression loads. When a CFRP composite tube is crushed, static/impact energy is consumed by friction between the loading plate and the splayed fronds of the tube, by fracture of the fibers, matrix and their interface. These are associated with the energy absorption capability. In general, CFRP tube with 6 interlaminar number(C-type), absorbed more energy than other tubes(A, B, D-types). The maximum collapse load seemed to increase as the interlaminar number of such tubes increases. The collapse mode depended upon orientation angle of outer of CFRP tubes and loading status(static/impact). Typical collapse modes of CFRP tubes are wedge collapse mode, splaying collapse mode and fragmentation collapse mode. The wedge collapse mode was shown in case of CFRP tubes with 0° orientation angle of outer under static and impact loadings. The splaying collapse mode was shown in only case of CFRP tubes with 90°orientation angle of outer under static loadings, however in Impact tests those were collapsed in fragmentation mode .

• Environmental Engineering Research
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• v.18 no.3
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• pp.163-168
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• 2013

In this study, an innovative media, iron mixed ceramic pellet (IMCP) has been developed for arsenic (As) removal from groundwater. A porous, solid-phase IMCP (2-3 mm) was manufactured by combining clay soil, rice bran, and Fe(0) powder at $600^{\circ}C$. Both the As(III) and As(V) adsorption characteristics of IMCP were studied in several batch experiments. Structural analysis of the IMCP was conducted using X-ray absorption fine structure (XAFS) analysis to understand the mechanism of As removal. The adsorption of As was found to be dependent on pH, and exhibited strong adsorption of both As(III) and As(V) at pH 5-7. The adsorption process was described to follow a pseudo-second-order reaction, and the adsorption rate of As(V) was greater than that of As(III). The adsorption data were fit well with both Freundlich and Langmuir isotherm models. The maximum adsorption capacities of As(III) and As(V) from the Langmuir isotherm were found to be 4.0 and 4.5 mg/g, respectively. Phosphorus in the water had an adverse effect on both As(III) and As(V) adsorption. Scanning electron microscopy results revealed that iron(III) oxides/hydroxides are aggregated on the surface of IMCP. XAFS analysis showed a partial oxidation of As(III) and adsorption of As(V) onto the iron oxide in the IMCP.

• Geomechanics and Engineering
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• v.12 no.4
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• pp.707-721
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• 2017

The objective of this paper is to experimentally study the consolidation of saturated silty clay subjected to repeated heating-cooling cycles using a modified temperature-controlled triaxial apparatus. Focus is placed on the influence of the water content, confining pressure, and magnitudes and number of thermal loading cycles. The experimental results show that the thermally induced pore pressure increases with increasing water content and magnitude of thermal loading in undrained conditions. After isothermal consolidation at an elevated temperature, the pore pressure continues to decrease and gradually falls below zero during undrained cooling, and the maximum negative pore pressure increases as the water content decreases or the magnitude of thermal loading increases. During isothermal consolidation at ambient temperature after one heating-cooling cycle, the pore pressure begins to rise due to water absorption and finally stabilizes at approximately zero. As the number of thermal loading cycles increases, the thermally induced pore pressure shows a degrading trend, which seems to be more apparent under a higher confining pressure. Overall, the specimens tested show an obvious volume reduction at the completion of a series of heating-cooling cycles, indicating a notable irreversible thermal consolidation deformation.

• Microbiology and Biotechnology Letters
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• v.16 no.3
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• pp.193-198
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• 1988

Catalase from Aspergillus niger KUF-04 was purified by five steps including gel filtration. The overall purification gave 64-fold purified preparation, a yield of about nine percent. The enzyme showed its maximum absorption at 406 nm. The optimum pH and temperature for the enzyme activity were around pH 7.0 and 6$0^{\circ}C$, respectively. The catalase was found to be stable in the range of pH 4.0 to pH 8.3 and temperature 2$0^{\circ}C$ to 6$0^{\circ}C$. However, it lost nearly all of the activity by heating at 8$0^{\circ}C$ for 20 min. The activity was markedly inhibited by hydroxylamine, potassium cyanide and sodium azide.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.295-301
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• 2012

The collagen-liposomes were prepared with hydrogenated phosphatidylcholine and by solvent injection method for maximum protection and stable absorption of collagen into the body. Cholesterol was added to phosphatidylcholine to increase the stability of liposome membrane. The mixture was dissolved in ethanol and propylene glycol and PBS Buffer was used to Stabilize ions. The properties collagen-liposome were analyzed by DLS, SEM and POM.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.6
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• pp.27-34
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• 2015

There has been a critical issue in optical simulation of phosphors in LEDs due to their light-reabsorption properties. To improve the accuracy of optical modeling for a white LED package, we utilized the spectrum data of the phosphor-dispersed encapsulant film instead of the phosphor powder. By measuring white LED packages with green and red phosphors, the maximum difference between simulation and experimental results of a color temperature, a color rendition index number and a color coordinate corresponds to ${\Delta}T=95K$, ${\Delta}Ra=1.7$ and ${\Delta}xy=0.007$, respectively. Based on those results, the proposed method can well explain the change of emission spectra of white LEDs with more than two phosphors which introduce the complex optical phenomena such as absorption, reabsorption, light emission, reflection and scattering, etc.

• Microbiology and Biotechnology Letters
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• v.7 no.1
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• pp.31-36
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• 1979

Yellow pigment was extracted by petroleum ether, and red pigment by 60％ ethanol. By thin layer chromatography red pigment preparation consists of more than five species whereas yellow pigment preparation consist of single species. The absorption curve of pigment solution exhibits maximum peak at wavelongth range of 495~500 nm and endo pigment at 394~403 nm. Pigment solution was relatively stable at the pH range of 3~9. Extracted pigment solution gave negative hemolysis test and pigment showed no bio-activity and nontoxicity.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.289-293
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• 2000

Diode-laser-pumped Tm:YAG laser of wavelength $2.02\mu\textrm{m}$has been manufactured and its excitation efficiency and output characteristics have been investigated. The excitation efficiency was varied from 66 to 68% with respect to the pump power, yielding pump power absorption of 87-89%. The output power was sensitively varied with the temperature of Tm:YAG rod. When the concave output coupler with a focal length of 25 mm and a transmittance of 3% was used, the maximum output power reached up to 1.2 W. The slope and optical efficiency of this Tm: YAG laser was 29% and 20% at $6^{\circ}C$, respectively.tively.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.175-180
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• 1998

Nd:YAG single crystal widely used as solid state laser was grown by Czochralski method. <111> single crystal with 0.9at% of $Nd^{3+}$ was grown from the Czochralski furnace with a automatic diameter control system. The vertical temperature gradient in the liquid was the major factor that influence the crystal quality, and the crystal diameter was controlled by the home made computer program. The crystal boule with $\phi$50mm$\times$ι100mm effective size was cut, polished, and antireflection coated. The optical evaluation such as absorption spectrum, fluorescence spectrum coincide with typical features of Nd:YAG single crystal. The laser rod was assembled into the CW laser generator with a Kr lamp. The maximum CW laser output was 70 W and the threshold power and efficiency was 1.3kW and 1.64% respectively.

• Korean Journal of Microbiology
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• v.15 no.4
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• pp.159-169
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• 1977

The bacteria of red colonies isolated from soil were identified as Serratia marcescens. The best solvent for pigment extraction was n-buthanol and the pigment was identified as prodigiosene. The extracted pigment was stable on temperature and light but not on acidity. The redpigment color changed into red in alkaline solution. The maximum absorbancy of pigment was 466 nm in alkaline condition and 540 nm in acid condition. And the pigment formed single spot on the TLC(starch). By the result of infra red spectrum, the red pigment has the same absorption pattern comparing with, the prodigisin produced by S. marcescens strain Nima. It was confirmed that the pigment was secondary metabolite and that the maximal peak of production appeared at 30 hrs after the inoculation, when the bacterial growth was in statinary state. Referring to the effect of temperature, the pigment was not formed at $36^{\circ}C$ and the optimal temperature for both of bactrial growth and pigmentation was $30^{\circ}C$. The optimal range of pH for pigmentation was 5.0 and under the condition the bacterial growth was not affected at all. Examining the effects of light, the bacterial pigment ation was more increased in darkness than in visible light.