• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.348-355
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• 1999

Effects of pH, sugars, organic acids, metal ions, ascorbic acid and light on the stability of anthocyanin pigment extracted from purple-fleshed potato (Solanum tuberosum L.) were studied. The pH had marked influences on the color of the potato anthocyanin pigment: i.e., the lower the pH of the anthocyanin solution was, the more stable and intenser of the pigment was. It showed characteristic bathochromic shift as the pH of the solution increased. Generally, the addition of sugars into the purple-fleshed potato anthocyanin solution caused decrease in color stability of the pigment. Among the sugars tested, maltose was the most deleterious followed by sucrose, galactose, fructose and glucose. The addition of organic acids greatly increased the stability of the pigment. Malic acid was found to be the most effective in stabilizing the pigment followed by tartaric, citric and succinic acids, while malonic acid was found to be deteriorative to the stability of the pigment. Most metal ions except $Cu^{2+}$ increased stability of the pigment-especially, $Cd^{2+}\;and\;Al^{3+}$ were more effective than the others. Ascorbic acid degraded the pigment considerably, but the adverse effect was diminished by adding thiourea. Light gave an adverse effect to the stability of the purple-fleshed potato anthocyanin pigment, which could be minimized by shielding the light from the pigment.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.352-359
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• 1996

Stabilities of purple sweet potato (PSP) anthocyanin pigment on pH, sugars, organic acids, metal ions, ascorbic acid and light were investigated to provide the basic information for utilization of PSP as a potential source of anthocyanin pigment. pH has a marked influences on the color of the PSP anthocyanin solution; i.e., at low pH the color of PSP was more intense and stable. It showed characteristic bathochromic shift as the pH of the solution increased. Among the sugars tested, glucose showed a protective effect on the color of PSP pigment to raise the color intensity and stability, while sucrose and fructose showed an adverse effect. Addition of organic acids greatly increased the stability of PSP anthocyanin pigment. Citric acid was found to be the most effective followed by malic. tartaric, and succinic acids. Most metal ions except $Al^{3+}$ and $Cd^{2+} were found to be detrimental effect on the stability of PSP pigment. Ascorbic acid degraded PSP pigment considerably, and had a synergistic effect with oxygen on the pigment degradation. The effect of light on PSP pigment was found to be very deleterious. The pigment degradation can be minimized by shielding the light from the pigment solution.

• Fire Science and Engineering
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• v.22 no.3
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• pp.216-220
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• 2008

Water mist fire suppression system utilizes the fire suppression features such as cooling of fire source, dilution of ambient oxygen, and shielding of radiation heat with the evaporation of microscopic water droplets. The momentum of water mist is relatively lower than that of larger water droplet and the infiltration of water mist to the fire source is not effective. Contribution of evaporated water vapor is liable to decline to limited portion of fire source due to its light weight and sparse density. On the other hand, the cycling water mist pattern is expected to improve the penetration force of water mist as well as the air expelling capability with the stratified spray characteristics. At this paper, we present the analyzed fire suppression capability of intermittent water spray pattern by use of FDS which is computational fire dynamics fire model. We expect this analysis can support the basic concept to the development of the prototype of water mist nozzle.

• Applied Chemistry for Engineering
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• v.9 no.3
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• pp.342-347
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• 1998

Light-weight conductive polymer composites were prepared by incorporating polyheterocycles such as polypyrrole and polythiophene into pores of a highly porous cross-linked polystyrene, host polymer, to form a conductive network. The highly hydrophobic and porous host polymer was synthesized by concentrated emulsion polymerization method. Polypyrrole-based composites, prepared by employing ferric chloride-methanol system, showed a conductivity as high as 0.82 S/cm. Conductivity of polythiophene-based composites, prepared from ferric chloride-acetonitrile system, was 6.05 S/cm. Conductivity of compositivity was influenced by the initial molar ratio of oxidant to monomer as well. SEM micrographs of the composites showed that conducting polymer coated uniformly the inside wall of the porous host polymer. Shielding effectiveness of the polypyrrole-based composites and of the polythiophene-based composites were 15.2 dB and 22.5 dB at 2.0 GHz, respectively. In the temperature range from 20 to 300K, a polypyrrole impregnated composite exhibited seimiconducting behavior and followed the variable range hopping(VRH) model for charge transport.

• Resources Recycling
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• v.20 no.1
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• pp.69-79
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• 2011

Recently, magnesium alloys are in the spotlight as a promising materials in the fields of automobile parts and electronic appliances due to their merits representing light weight, high specific strength, damping property, shielding of electromagnetic wave and so on. However, magnesium alloys show a poor formability at room temperature because magnesium has HCP crystal structure with limited slip planes and strong basal texture is formed during plastic deformation process such as rolling and extrusion. Therefore, many R&D efforts have been paid for improvement of formability through grain refinement, texture control and various forming technologies. This paper is giving an overview about recent achievements on control of microstructures, forming technologies and magnesium scrap recycling.

• Wind and Structures
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• v.3 no.3
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• pp.143-158
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• 2000

This report presents the findings of a one-year monitoring effort to empirically characterize and evaluate the nature of near-ground winds for structural engineering purposes. The current wind engineering practice in the United States does not explicitly consider certain important near-ground wind characteristics in typical rough terrain conditions and the possible effect on efficient design of low-rise structures, such as homes and other light-frame buildings that comprise most of the building population. Therefore, near ground wind data was collected for the purpose of comparing actual near-ground wind characteristics to the current U.S. wind engineering practice. The study provides data depicting variability of wind speeds, wind velocity profiles for a major thunderstorm event and a northeaster, and the influence of thunderstorms on annual extreme wind speeds at various heights above ground in a typical rough environment. Data showing the decrease in the power law exponent with increasing wind speed is also presented. It is demonstrated that near-ground wind speeds (i.e., less than 10 m above ground) are likely to be over-estimated in the current design practice by as much as 20 percent which may result in wind load over-estimate of about 50% for low-rise buildings in typical rough terrain. The importance of thunderstorm wind profiles on determination of design wind speeds and building loads (particularly for buildings substantially taller than 10 m) is also discussed. Recommendations are given for possible improvements to the current design practice in the United States with respect to low-rise buildings in rough terrain and for the need to study the impact of thunderstorm gust profile shapes on extreme value wind speed estimates and building loads.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.620-625
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• 2002

Considering the fuel consumption of car, a light structure of aluminum alloys is desired for car body nowadays. However, fusion welding of aluminum alloys has some problems of reduction of joint efficiency, porosity formation and hot cracking. ill the present work, investigation to improve the joint performance of laser welded joint has been carried out by addition of Cu, Ni, and Zr to A6N01 alloy welds. Aluminum alloy plate of 2.0mm in thickness with filler metal bar was welded by twin beam Nd:YAG laser facility (total power:5kW). The filler metals were prepared by changing the chemical compositions for adding the elements into the weld metal. Thirteen filler metal bars were prepared and pre-placed into the base metal before welding. Ar gas shielding with a flow rate of 10 l/min was used. The defocusing distance is kept at 0 mm. At travel speeds of 3 to 9 m/min and at laser power of 5kW (front beam 2kW rear beam 3kW), full penetration welds were obtained, whereas at travel speeds of 12 to 18 m/min and same power, partial penetration was observed. The joint efficiency of laser-welded joint was improved by the addition of Cu, Ni, and Zr due to the solid solution hardening, grain refining and precipitation hardening. The type of hardening has been further considered by metallurgical examination.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.4
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• pp.19-22
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• 2007

Recently, the population of people exploring High Mountain trekking or expedition is increasing as an increase in the backpackers. Many accidents occurring at High Mountain above 6,000 m are the results of snow blindness. The damage of cornea and/or retina is direct cause of snow blindness. The UV intensity increases on the hand, along with the altitude caused by decrease in the atmospheric pressure, on the other hand the reflections by bright snow at high mountain area. And it increases approximately 3 times and 4 times higher than the ground level at altitude of 4,000 m and 8,000 m, respectively. The use of sunglasses is more favorable than goggles for the protection of snow blindness at High Mountains. The eye frames that have high mechanical strength and the plastic lenses which can protect UV 100% are recommended. The attachable shielding pads are needed to prevent the incident UV light reflected or scattered from the gap between glasses frame and face. The sunglasses must have flexible and long temples to wind the ears adequately for the prevention of detachment during climbing and it is recommended that the metal frame to be coated with plastics to prevent the eye surroundings from frostbite.

• International Journal of Korean Welding Society
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• v.2 no.2
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• pp.26-31
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• 2002

Considering the fuel consumption of car, a light structure of aluminum alloys is desired fer car body nowadays. However, fusion welding of aluminum alloys has some problems of reduction of joint efficiency, porosity formation and hot cracking. In the present work, investigation to improve the joint performance of laser welded joint has been carried out by addition of Cu, Ni, and Zr to A6NO 1 alloy welds. Aluminum alloy plate of 2.Omm in thickness with filler metal bar was welded by twin beam Nd: YAG laser facility (total power: 5kW). The filler metals were prepared by changing the chemical compositions for adding the elements into the weld metal. Thirteen filler metal bars were prepared and pre-placed into the base metal before welding. Ar gas shielding with a flow rate of 10 1/min was used. The defocusing distance is kept at 0 mm. At travel speeds off 3 to 9 and at laser power of 5kW (front beam 2kW rear beam 3kW), full penetration welds were obtained, whereas at travel speeds of 12 to 18 m/min and same power, partial penetration was observed. The joint efficiency of laser-welded joint was improved by the addition of Cu, Ni, and Zr due to the solid solution hardening, grain refining and precipitation hardening. The type of hardening has been further considered by metallurgical examination.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2005.05a
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• pp.213-215
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• 2005

The metal complexes can be influenced not only by the central metal atoms and the substituent groups, but also by the native of the chelating atoms. For example, near-infrared absorbing chromophores were synthesized by the reaction of phenylenediamine derivatives with a solution of pottassium hydroxide followed by the addition of nickel(II) chloride. These dyes provide absorbing infrared light over 780-840 nm with an extinction coefficient of $2.5-6.0{\times}10^4$. By introduction of alkyl, alkoxyl, cyano, and other functional group into the parent dye, these dyes greatly improved the solubility in organic solvent. New near-infrared absorbing donor-acceptor chromophores have been investigated by varying the electron donating and accepting strength of the two halves of the molecule. The cyanine chromophores permit the simplest way of obtaining systems that absorb well into the near-infrared region of the spectrum. Cyanine dyes possess high extinction coefficients that initially increase with Increasing chain length. These chromophores could be useful in near-infrared optical materials.