• Bulletin of the Korean Chemical Society
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• 제23권9호
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• pp.1235-1267
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• 2002

A series of 2,5-dialkoxy substituted poly(1,4-phenylenevinylene) derivatives containing a rigid and bulky cyclohexyl group in the side chain, poly[2-(7-cyclohexylheptyloxy)-5-butoxy-1,4-phenylenevinylene] (PBCyHpPV), Poly[2-(6-cyclohexylmethoxyhexyloxy)-5-butoxy-1,4-phenylenevinylene] (PBCyHxPV), Poly[2,5-di-(6-cyclohexylmethoxy-hexyloxy)-1,4-phenylenevinylene] (PDCyHxPV) were synthesized via the Gilch polymerization. The synthesized polymers were soluble in common organic solvents and showed good thermal stability up to $370^{\circ}C$. The maximum absorption of PBCyHpPV, PBCyHxPV and PDCyHxPV as thin films was at 513 ㎚, 515 ㎚, 511 ㎚, respectively. Photoluminescence maximum emission of above polymers appeared at 590 ㎚, 597 ㎚, 590 ㎚, respectively. The electroluminescence (EL) maxima of the polymers appeared around 585-590 ㎚, and also showed another shoulder around 630 ㎚ strongly. PDCyHxPV showed the highest EL efficiency and EL power than those of other polymers due to the dilution effect of the two rigid and bulky cyclohexyl groups.

• 한국운동역학회지
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• 제22권2호
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• pp.243-251
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• 2012

The purpose of this study was to develop an impact force measurement device in order to facilitate the acquisition of quantitative data for the analysis of various sporting events. The device was designed to include cylindrical aluminum supports of 220 mm diameter, which allows mounting and dismounting of the device on walls and frames. In addition, a hard sponge for impact absorption, as well as 4 springs, were attached to the plate. Both were attached to prevent psychological variables and injuries. When a subject applies force on the device, accurate data about the maximum repulsive force is acquired in real time, with a lag of only 0.001 s. The device was calibrated in four steps: (1) increase, (2) increase, (3) increase-decrease, and (4) increase-decrease. The maximum relative expanded uncertainty was 0.166%, indicating that the impact force measurement was sufficiently reliable. The proposed device can be applied to various sporting situations and is expected to be useful for studying kinetics.

• Agricultural and Biosystems Engineering
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• 제1권1호
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• pp.16-21
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• 2000

Measurement of spray deposit is necessary for evaluation of a chemical application technology. However it is not easy and time consuming. A simple method for measuring the deposition amount of spray using a tracer and a spectrophotometer was developed. Various materials were tested to determine an adequate tracer. Food dye was selected as a tracer, because it was cheep and easily treatable. Using NIRS(Near Infrared Reflection Spectrophotometer), a regression curves between maximum absorbance of a solution and concentration of the tracer were obtained. Yellow food dye solution showed a peak of spectrum at 452 nm, and absorbance of peak showed a tendency to increase as concentration increased. Green or pink food dye were tested and judged to be good tracers. However, tracer concentration should not exceed certain limits in order to measure maximum absorption. Using spraying liquid with known tracer concentration and known amount of washing liquid, spray deposit amount on real targets on leaves could be estimated at less than 13% error level.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.631-636
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• 2002

This study shows basic data for using as the structural lightweight aggregate. This will be the procedural method of recycling environmental close waste PET bottle lightweight aggregate(PBLA) that is rapidly increased the amount of production of waste PET bottle recently, the quality of developed PBLA and the fundamental properties by analyzing of mortar containing with PBLA. After experiment, the result shows the PBLA quality that have oven dry specific gravity of 1.39, unit volume weight of 844 kg/m$^3$ and absorption rate of 0% is satisfied with qualify regulation of lightweight aggregate. The flowability of mortar containing PBLA is increased maximum 16% with increasing mixing ratio of PBLA, however the compressive strength of mortar is decreased maximum 35% with increasing mixing ratio of PBLA.

• Journal of Ginseng Research
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• 제3권2호
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• pp.127-133
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• 1979

A simple and rapid colorimetric method for determination of panaxadiol and , panaxadiol was developed. 1. After heating with 60% perchloric acid, panaxadiol and panaxadiol yielded red.purple color with absorption maximum at 540 nm and 538 nm, respectively. 2. The maximum colors of the Panaxadiol and panaxadiol were reached when the algycones were treated at 6$0^{\circ}C$, 5 minutes or 7$0^{\circ}C$ 3 minutes. 3. The absorbance varied linearly with the amount of aglycone in the reaction mixture. And the colorimetric method was sensitive to about 10$\mu\textrm{g}$ of aglycone in 5.5ml of the reaction mixture. 4. The color was stable for about a week at 4$^{\circ}C$. 5. $\beta$-Sitosterol, oleanolic acid and cholesterol were not yielded red color by treatment with 60% perchloric acid under the conditions described.

• 한국세라믹학회지
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• 제33권5호
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• pp.479-484
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• 1996

The tribological properties of ceramics are very important in the application to engineering ceramic parts such as mechanical seal slurry valve disc and so on. In this study the effect of graphite addition on the mechanical and tribological properties of RBSC/graphite composites were investigated. The composites were prepared by adding graphite powder to the mixture of SiC powder metallic siliconcarbon black and alumina. Bending strength water absorption friction coefficient the amount of worn out material at a certain time and maximum surface roughness(Rmax) of the prepared composites were measured and crystalline phases were examined with XRD. The composite containing 5 vol% graphite powder showed improved bending strength due to high green density and decreased friction coefficient and wear resistance. The friction coefficient and the wear resistance of the composite were increased by adding graphite powder up to 10 vol% They decreased however as increasing the amount of graphite powder more that 10vol% There was no linear relationship between the tribological properties and bending strength of the composites.

• 한국세라믹학회지
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• 제34권4호
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• pp.380-386
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• 1997

The tribological properties of ceramics are very important in the application to engineering ceramic parts such as seal rings, pump parts, thread guides, and so on. In this study, the effects of graphite addition on the mechanical and tribological properties of alumina/graphite composites were investigated. The composites were prepared by the adding of graphite powder to the mixture of Al2O3, talc and calcium carbonate. Bending strength, water absorption, friction coefficient, the amount of worn out material at a certain time, and maximum surface roughness(Rmax) of the prepared composites were measured. Crystalline phases and microstructure were examined with XRD and SEM. The melt of Al2O3-CaO-MgO-SiO2 system was shown over 10 vol% graphite composition. As the amount of the graphite is increased, needle like crystals of mullite were formed and grown. We obtained the good properties of friction coefficients and wear resistance at the powder composition containing 15 vol% of graphite.

• 국제물리치료학회지
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• 제2권1호
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• pp.222-228
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• 2011

With comparison of maximum vertical reaction force and lower limb on drop landing between normal and flat foot group, this study is to provide fundamental data of the prevention of injury and the treatment of exercise which are frequently occurred on flat foot group's drop landing. The surface electrodes were sticked on lateral gastrocnemius muscle, medial gastrocnemius muscle, tibialis anterior and the drop landing on a force plate of 40cm was performed with a normal group who had no musculoskeletal disease and a flat foot group of 9 people who had feet examinations. Vertical reaction force were significantly statistically different between two groups(p<.001). Muscle activity of lower limbs in all three parts were not statistically different but showed high tendency on average in the flat foot group. The flat foot group had difficulties in diversification of impact burden and high muscle activity. Therefore, it was suggested that muscular strengthening of knee joints and plantar flexions of foot joints which were highly affected in impact absorption will be required.

• 동아시아식생활학회지
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• 제15권3호
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• pp.334-339
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• 2005

This study was conducted to test the white bread dough with substitution of 1, 2, 3, 4 and $5\%$ kimchi powder on farinograph, extensograph, amylograph, and pH to find the dough development time, stability, extensibility, resistance to extension, temperature at gelatinization, and temperature at maximum viscosity. Dough with kimchi powder showed less moisture absorption than control. Upon increasing amount of kimchi powder, pH was decreased and dough development time was increased Extensibility of dough showed negative correlation with amount of kimchi powder added Gelatinization temperature increased but maximum viscosity temperature decreased as the amount of kimchi powder increased Overall, the samples with substitution of kimchi powder showed better extensibility than the control sample at the first fermentation.

• Journal of Plant Biology
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• 제13권1호
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• pp.25-32
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• 1970

Ecological study on the reclaimed high saline soil was carried out throughout a year(1969) to elucidate the changes of the structure of halophytes communiteis and the possibilities of desalination from high saline soil by absorption of chloride ion. Results from this studies are summarized as followings; 1) The growth rates of halophytes showed a variation; maximum growth rate of Salicornia appeared on August, Chenopodium on July, Suaeda on July, Aster on August and Scirpus on June. 2) Changes of frequency of each halophyte were varied in accordance with species. Chenopodium and Salicornia have the highest frequency of all on May. However, frequency as well as density of halophytes decreased after on May due to competition for absorbing moisture in plant communities. 3) The terrestrial plants which were succeed into the reclaimed tidal land had herborized 25 species on the both side of irrigation route. 4) Each of the maximum chloride uptake by halophytes appeared on May(Salicornia and Aster), on June(Chenopodium and Scirpus), and on August(Suaeda), respectirecely 5) Among the halophytes, Salicornia was confirmed to absorb the highest amount of chloride. A possible amount of chloride uptake by all halophytes per 100 square cm reached about 24,629. ppm.