• Analytical Science and Technology
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• v.8 no.3
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• pp.249-258
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• 1995

The polymers, polyazine, polyazomethine ( I ) and polyazomethine ( II ) were prepared by the condensation of p-benzoquinone with hydrazine hydrate, p-phenylenediamine and diaminomaleonitrile in DMSO, respectively. The IR spectra of these polymers showed a characteristic peak of schiff base (-C=N-) at about $1600cm^{-1}$. These polymers dissolved in concentrated sulfuric acid showed UV/VIS absorption near 300nm indicatiog the presence of iminium ion(>$C\limits^{\small\oplus}=NH-$). Another UV/VIS absorption band in the region of 350~415nm was shown presumably due to the charge transfer transition in the molecule. The electrical conductivities of polyazine, polyazomethine ( I ) and ( II ) were measured. The self-electrical conductivity of these was found to be about $10^{-14}{\sim}10^{-11}{\Omega}^{-1}cm^{-1}$ and these polymers doped with $I_2$ showed the maximum conductivity of about $10^{-2}{\Omega}^{-1}cm^{-1}$.

• Journal of Magnetics
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• v.18 no.2
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• pp.150-154
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• 2013

$La_{1-z}Nd_z(Fe_{0.88}Si_{0.12})_{13}$ and their hydrides were investigated to obtain large magnetocaloric effects (MCEs) in a wide temperature range, including room temperature, for applications in magnetic refrigents. Since the magnetization change due to the itinerant-electron metamagentic (IEM) transition for $La_{1-z}Nd_z(Fe_{0.88}Si_{0.12})_{13}$ becomes larger with increasing z, the isothermal magnetic entropy change ${\Delta}S_m$ and the relative cooling power (RCP) are enhanced. In addition, the Curie temperatrue $T_C$ of $La_{0.8}Nd_{0.2}(Fe_{0.88}Si_{0.12})_{13}$ is increased from 193 to 319 K by hydrogen absorption, with the IEM transition. The maximum value of $-{\Delta}S_m$, $-{\Delta}S{_m}^{max}$, in a magnetic field change of 2 T for $La_{0.8}Nd_{0.2}(Fe_{0.88}Si_{0.12})_{13}H_{1.1}$ is about 23 J/kg K at $T_C$ = 288 K, which is larger than that of 19 J/kg K at $T_C$ = 276 K for $La(Fe_{0.88}Si_{0.12})_{13}H_{1.0}$. The value of RCP = 179 J/kg of the former is also larger than 160 J/kg of the latter. It is concluded that the partial substitution of Nd improves MCEs in a wide temperautre range, including room temperature.

• Polymer(Korea)
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• v.37 no.2
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• pp.148-155
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• 2013

The purpose of this study is to clarify the effect of the emulsifier ratio on the properties of the polymer cement mortars based on styrene-butyl acrylate (S/BA) latexes, and to obtain necessary basic data to develop appropriate latexes for cement modifiers. The polymer dispersions for cement modifiers was synthesized using styrene and butyl acrylate. Polymer cement mortars based on S/BA latexes were prepared with various monomer and emulsifier ratios, and their water-cement ratio, air content, flexural and compressive strengths, water absorption and chloride ion penetration were tested. From the test results, the maximum flexural and compressive strengths of polymer cement mortars based on S/BA latexes were obtained at a bound styrene content of 60% and an emulsifier ratio of 6%. Also, the water absorption and chloride ion penetration depth are greatly affected by the polymer-cement ratio rather than the bound styrene and emulsifier content. Accordingly, it is judged that S/BA latexes can be used place of the conventional polymer dispersions of cement modifier.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3399-3404
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• 2013

A new accepter unit, pyrrolo[3,2-b]pyrrole-2,5-dione, was prepared and utilized for the synthesis of the conjugated polymers containing electron donor-acceptor pair for OPVs. Pyrrolo[3,2-b]pyrrole-2,5-dione unit, regioisomer of the known pyrrolo[3,4-c]pyrrole-1,4-dione, is originated from the structure of stable synthetic pigment. The new conjugated polymers with 1,4-diphenylpyrrolo[3,2-b]pyrrole-2,5-dione, thiophene and carbazole were synthesized using Suzuki polymerization to generate P1 and P2. The solid films of P1 and P2 show absorption bands with maximum peaks at about 377, 554 and 374, 542 nm and the absorption onsets at 670 and 674 nm, corresponding to band gaps of 1.85 and 1.84 eV, respectively. To improve the hole mobility of the polymer with 1,4-bis(4-butylphenyl)-pyrrolo[3,2-b]-pyrrole-2,5-dione unit, which was previously reported by us, the butyl group at the 4-positions of the N-substituted phenyl group was substituted with hydrogen and methyl group. The field-effect hole mobility of P2 is $9.6{\times}10^{-5}cm^2/Vs$. The device with $P2:PC_{71}BM$ (1:2) showed $V_{OC}$ value of 0.84 V, $J_{SC}$ value of 5.10 $mA/cm^2$, and FF of 0.33, giving PCE of 1.42%.

• Korean Journal of Materials Research
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• v.3 no.5
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• pp.505-513
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• 1993

To make the electrophotographic photoreceptor that srnsirizes for panchromatic matcrial, the dying element of sunfasr yellow which has an absorption ivavclength at near 400nm, and $\alpha,\beta$-copper phthalocyaninc dying elements with 700nm absorption wavelength were adsorbed and then dispersed onto the zine oxide(Zn0). In ordcr to characterize rhe change In sensitivity the various binders and different mole ratio of ZnO to binder were employed in here. It was found rhat the optimum sensitivity was obtained with 5.5 ratio. I;rom the measurements of electrostatic and spectral sensitivity, it was found that the maximum photographic properties were obtained for mixing the sunfast yellow and $\beta$-copper phthalocyaninr. In this case the electrophotographic sensiri\ity was found to he $E{1:2}$= 1440 lux . sec. And also the spectral sensitivity shows that it had a good properties for panchromatic matcrial.

• Korean Journal of Applied Biomechanics
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• v.29 no.4
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• pp.255-261
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• 2019

Objective: The purpose of this study was to investigate differences of shock attenuation strategies between double-leg and single-leg landing on sagittal plane using statistical parametric mapping. Method: Nine healthy female professional soccer players (age: 24.0±2.5 yrs, height: 164.9±3.3 cm, weight: 55.7±6.6 kg, career: 11.2±1.4 yrs) were participated in this study. The subjects performed 10 times of double-leg and single-leg landing from the box of 30 cm height onto force plates respectively. The ground reaction force, angle, moment, angular velocity, and power of the ankle, knee, and hip joint on sagittal plane was calculated from initial contact to maximum knee flexion during landing phase. Statistical parametric mapping was used to compare the biomechanical variables of double-leg and single-leg landing of the dominant leg throughout the landing phase. Each mean difference of variables was analyzed using a paired t-test and alpha level was set to 0.05. Results: For the biomechanical variables, significantly increased vertical ground reaction force, plantarflexion moment of the ankle joint, negative ankle joint power and extension moment of the hip joint were found in single-leg landing compared to double-leg landing (p<.05). In addition, the flexion angle and angular velocity of the knee and hip joint in double-leg landing were observed significantly greater than single-leg landing, respectively (p<.05). Conclusion: These findings suggested that negative joint power and plantarflexion moment of the ankle joint can contribute to shock absorption during single-leg landing and may be the factors for preventing the musculoskeletal injuries of the lower extremity by an external force.

• Korean Journal of Food Science and Technology
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• v.25 no.3
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• pp.214-219
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• 1993

Properties of the antioxidative fraction isolated from browning reaction product (BRP) that were obtained from 2 M L-ascorbic acid (AsA) solution (adjusted to pH 7.0) by heating for 25 hrs at $85^{\circ}C$ were investigated. Both of dialyzable and nondialyzable fraction isolated from BRP showed antioxidative effect. Dialyzable fraction has stronger antioxidative activity than nondialyzable. Dialyzable fraction was divided into the three fractions (A, B, C) by gel filtration. Among these fractions, the fraction (A) that had the highest reducing power and lowest browning drgree had lowest antioxidative activity. The fraction (C) that had lowest reducing power and highest browning degree showed strongest antioxidative effect. In the UV-visible spectrum of these fractions, the maximum absorption wavelengths of fraction A and B were 266.1 and 257.4nm, respectively, and fraction C showed a weaker absorption peak at 274.8nm. Infrared (IR) spectrum results showed that all fractions (A, B, C) had both hydroxy and carboxylic groups, and fraction B and C had carboxylic ester group.

• Journal of Korea Foundry Society
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• v.24 no.6
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• pp.356-365
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• 2004

Mechanical properties and microstructures of the Ni-AI-Fe and Ni-AI-Fe-(B, Zr) alloys which containing $10{\sim}30at$.%Fe, 0.1at.%B and/or 0.1at.%Zr have been investigated. The experimental results showed that the microstructures of Ni25Al were changed from a single phase ${\gamma}$ to dual phase ${\gamma}$ and ${\beta}$ by addition of 27at.%Fe. Ni45Al, however, kept the single ${\beta}$ phase even though Fe was added upto 30at.%. The hardness of Ni25Al were increased from $H_RB$ 70 to $H_RC$ 39 by addition of 27at.%Fe. In the case of Ni45Al which have $H_RC$ 37, the hardness was decreased by lOat.%Fe addition, but increased with 30at.%Fe. The yield strength and ultimate compressive strength in the compressive test have showed a similar trend with the hardness change. The strain to fracture was 14% at maximum and achieved in Ni25Al-27at.%Fe and Ni25Al-27at.%Fe-0.1 at.%B alloys. The Ni45Al showed a relatively low strain to fracture as 4%. The impact absorption energy of Ni25Al increased from 0.74 kg-m to 1.81 kg-m by addition of 27at.%Fe. In case of Ni45Al, the addition of lOat.%Fe and lOat.%Fe with small amounts of Band Zr did not change significantly the impact absorption energy of 0.60 kg-m, whereas the addition of 30at.%Fe with small amounts of B and Zr increased it slightly. In fracture tests, both of two basic materials showed the same intergranular fracture but by adding Fe it changed to the cleavage fracture mode or co-existing of cleavage and intergranular fractures.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1633-1637
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• 2010

The UV-vis absorption spectrum of protoporphyrin IX shows a very sharp and strong absorption maximum peak at 398 nm in acetonitrile-water mixture solution (1:1 v/v). When divalent metal ions such as $Cu^{2+}$, $Zn^{2+}$, and $Ca^{2+}$ ion were added to protoporphyrin IX, metal protoporphyrin IX complexes were thereby produced. Cu-protoporphyrin IX complexes have the largest formation constant ($K_f$) among them. The fluorescence intensity of protoporphyrin IX was diminished by the presence of $Cu^{2+}$, $Zn^{2+}$, $Ca^{2+}$, $Mn^{2+}$, and $Ni^{2+}$ ions as quenchers. However, $Mg^{2+}$, $Mn^{2+}$, and $Ni^{2+}$ ions are hardly combined with protoporphyrin IX. $Mg^{2+}$ ion does not take part in the fluorescence quenching process of protoporphyrin IX in acetonitrile-water mixture solution. According to the Stern-Volmer plots, fluorescence quenching by $Cu^{2+}$, $Zn^{2+}$, and $Ca^{2+}$ ions involves static quenching, which is due to complex formation. On the contrary, dynamic quenching has a large influence on the overall quenching process, when $Mn^{2+}$ and $Ni^{2+}$ ions were added to protoporphyrin IX in acetonitrile-water mixture solution.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.5
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• pp.817-823
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• 1996

The rheological prouerties of dough were evaluated the dough added whole wheat flour during breadmaking. From the farinogram, water absorption of the dough was decreased as the amount of coarse whole wheat flour was increased. While water absorption of the dough was increased as the amount of fine whole wheat flour was increased. Arrival time and development time of the dough with coarse whole wheat flour were longer than those of fine whole wheat flour. As the amount of whole wheat flour was increased, the weakness was increased. Weakness of coarse whole wheat flour was higher than that of fine whole wheat flour. From the extensograph, extension and resistance to extension were decreased with increasing the amount of whole wheat flour. Resistance to extension of coarse whole wheat flour was higher than that of fine whole wheat flour. From the amylograph, as the amount of whole wheat flour increased, maximum viscosity was decreased gradually. Though the amount of coarse whole wheat flour and fine whole wheat flour was increased up to 30% and 50%, respectively, external characteristics of bread was remained in normal. As the amount of whole wheat flour was increased, the value of whiteness was decreased.