• Macromolecular Research
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• v.12 no.1
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• pp.127-133
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• 2004

We have studied the surface micelle formation of polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) at the air-water interface. A series of four PS-b-P2VPs were synthesized by anionic polymerization, keeping the PS block length constant (28 kg/㏖) and varying the P2VP block length (1, 11, 28, or 59 kg/㏖). The surface pressure-area ($\pi$-A) isotherms were measured and the surface morphology was studied by atomic force microscopy (AFM) after Langmuir-Blodgett film deposition onto silicon wafers. At low surface pressure, the hydrophobic PS blocks aggregate to form pancake-like micelle cores and the hydrophilic P2VP block chains spread on the water surface to form a corona-like monolayer. The surface area occupied by a block copolymer is proportional to the molecular weight of the P2VP block and identical to the surface area occupied by a homo-P2VP. It indicates that the entire surface is covered by the P2VP monolayer and the PS micelle cores lie on the P2VP monolayer. As the surface pressure is increased, the $\pi$-A isotherm shows a transition region where the surface pressure does not change much with the film compression. In this transition region, which displays high compressibility, the P2VP blocks restructure from the monolayer and spread at the air-water interface. After the transition, the Langmuir film becomes much less compressible. In this high-surface-pressure regime, the PS cores cover practically the entire surface area, as observed by AFM and the limiting area of the film. All the diblock copolymers formed circular micelles, except for the block copolymer having a very short P2VP block (1 kg/㏖), which formed large, non-uniform PS aggregates. By mixing with the block copolymer having a longer P2VP block (11 kg/㏖), we observed rod-shaped micelles, which indicates that the morphology of the surfaces micelles can be controlled by adjusting the average composition of block copolymers.

• Korean Journal of Optics and Photonics
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• v.17 no.1
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• pp.68-74
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• 2006

We have extracted an optical clock signal from a return-to-zero(RZ) pseudorandom bit sequence(PRBS) and non-return-to-zero(NRZ) PRBS data in a pulsation multi-section laser diode with DFB reflector. The ms timing jitter achieved less than 1 ps for the input 11.727 Gbit/s RZ PRBS and NRZ PRBS data. The PRE data wasconverted from the NRZ data using an NRZ to pseudo-return to zero(PRZ) converter module. The optical clock was extracted from the PRZ data which contains the clock components. Although the input PRZ data gives a timing jitter of 2 ps, the extracted clock has timing jitter of ${\~}$1 ps.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.610-615
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• 2010

This study was conducted to evaluate fertigation effects of pig slurry (PS) and chemical fertilizer (CF) in tomato by analyzing the growth and yield, nutrient content and uptake, nutrient use efficiency, and soil characteristics in greenhouse cultivation. The treatments compared were; no-fertilizer, two different levels of PS (26 mg $L^{-1}$ and 52 mg $L^{-1}$), and a control treatment of chemical fertilizer. There was no significant difference in growth and yield between PS and CF treatments. however, yield reduction was observed in PS 26 mg $L^{-1}$ treatment. The N-utilization efficiency in CF treatment was similar to that of PS 52 mg $L^{-1}$ treatment. Nutrient utilization efficiency decreased in order of potassium (K), nitrogen (N), phosphate (P) with 29.2~43.3% in K, 15.8~36.7% in N, and 3.0~6.3% in P. In soil chemical characteristics, soil pH in PS treatment was higher than in CF treatment. In contrast, nitrate content in soil was higher in CF treatment than in PS treatment. The content of exchangeable K in soil was higher in PS and CF 52 mg $L^{-1}$ treatments. There was no significant difference in exchangeable Ca and Mg among those treatments. Therefore, it can be concluded that chemical fertilizers can be substituted by PS based on soil chemical analysis in tomato fertigation culture.

• Macromolecular Research
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• v.16 no.2
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• pp.178-181
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• 2008

Polystyrene (PS) nanospheres with a monodisperse size distribution, positive surface charge and high molecular weight were successfully synthesized using various types of metal stearates in an aqueous NaOH medium. The diameter of the PS nanospheres was controlled from 80 to 450 nm by changing the type of metal stearate. It was also found that controlling the NaOH concentration in solution was important for producing monodisperse PS nanoparticles. The nanospheres prepared with zinc stearate possessed a positive surface charge of 60 to 80 mV, confirming that PS particles were functionalized with metal stearates. It is believed that the metal stearates provide PS particles with not only colloidal stability but also a positive surface charge.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.3
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• pp.352-358
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• 2016

A 5-phase phase-locked loop (PLL) for USB2.0 applications was implemented by using an all-synthesis technique. The length of the time-to-digital converter for the fine phase detector was halved by the operation of a coarse phase detector that uses 5-phase clocks. The maximum time difference between the rising edges of two adjacent-phase clocks was 6 ps at 480 MHz. The PLL chip in a 65-nm process occupies $0.038mm^2$, consumes 4.8 mW at 1.2 V. The measured rms and peak-to-peak output jitters are 8.6 ps and 45 ps, respectively.

• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.180-186
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• 1987

Cell suspensions of two isolates of Pseudomonas syringae. PS8401 from sweet persimon and PS8402 from tea plant, were active in ice nucleation at -2.5 and $-3.8^{\circ}C$, respectively. Ice nucleation at those temperature was, using micropipette method, detected in suspensions ($10^8$ olony forming unit/ml of distilled water) of cells that had been grown on nutrient agar supplemented with $2.5\%$ glycerol. Using the same method, on the other hand, the freezing temperature of distilled water only was approx. $-21.8^{\circ}C$, and those of various plant saps including corn were lower than $-11.6^{\circ}C$. Corn seedlings sprayed with cell suspensions $(10^8\;cfu/ml)$ of nutrient broth) of PS8401 began to be damaged at $-2^{\circ}C$ and were almost completely damaged at $-4^{\circ}C$, whereas seedlings sprayed with nutrient broth only were not injured until the temperature down to $-9^{\circ}C$. Amounts of frost damage measured 48 hr after application of PS8401 suspensions increased as applied bacterial cell densities were increased. Ice-nucleation activity of the cell suspensions in vitro increased with increasing the number of cells in suspension. The activity also affected by growth-medium composition or growth-temperature. Ice nucleation thus occured at -4.0, -4.4 and $-7.2^{\circ}C$ in suspensions $(10^2\;cfu/ml)$ of PS8401 that had been grown at$25\%$ nutrient agar with $2.5\%$ glycerol, nutrient agar with $2.5\%$ glucose and nutrient agar only, respectively, and occured at -4.0 and $-7.6^{\circ}C$ in suspensions $(10^2\;cfu/ml)$ of PS8401 hat had been grown on nutrient agar with $2.5\%$ glycerol at $15\~25^{\circ}C$ and $30^{\circ}C$, respectively.

• Journal of Life Science
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• v.13 no.4
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• pp.463-472
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• 2003

Interactions between factor Va (HFVa) and membrane phosphatidylserine (PS) regulate the activity of the prothrombinase complex. I have previously shown that two solvent exposed hydrophobic residues located in the C2-domain, Trp2063 and Trp2064, are required for binding to immobilized PS and for expression of procoagulant activity on membranes containing 5% PS. In order to fully define the functional importance of these two residues I have expressed and isolated recombinant factor Va (rHFVa) W2063A/W2064A double mutant. In contrast to the native protein the two glycoforms resulting from alternative glycosylation of Asn2181 eluted as a single peak with rHFVa1 W2063A/W2064A eluting on the leading edge and rHFVa2 W2063A/W2064A eluting on the trailing edge. The double mutant rHFVa2 W2063A/W2064A expressed little or no procoagulant activity on membranes containing 1-10% mol % PS. In contrast, the procoagulant activity of this mutant was slightly greater than the native protein on membranes containing>18 mol % PS. The binding of rHFVa2 W2063A/W2064A to immobilized phospholipid vesicles was markedly reduced compared to the native protein in a surface plasmon resonance binding assay. I conclude that Trp2063 and Trp2064 are required for high affinity binding of factor Va to PS membranes and that this interaction is necessary for assembly of the prothrombinase complex on membranes containing physiological concentrations of PS.

• The Journal of Korean Physical Therapy
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• v.10 no.1
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• pp.7-21
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• 1998

An analysis of 101 stroke patients who were enrolled in 10 hospitals of Cities of Pusan, Taegu, and Andong from November 1, 1996 to April 31. 3997 was conducted using the modified Barthel Index(BI) and the adapted PULSES profile index(PS) to evaluate their function. Patients were examined at the following intervals: Initial assessment, one month after initial. at discharge, and one month after discharge. The mean BI score of patients initial assessment was 27.18, and that of PS was 17.54. There were statistically significant between initial score and one month after initial (21.39: p<0.001), at discharge(37.47: p<0.001), one month after discharge(46.49: p<0.001). PS scores were also improved .significantly(-2.62, -4.52. and -6.26(p<0.001). And the score between dischange and one month after discharge was significant (9.01: p<0.001) and in PS score(-1.73: p<0.001). Age and BE score were significantly associated with the improved in BI score between initial and discharge(T3-T1)(p<0.05). Below age forty the Bower initial BI score showed significantly higher improvement(T3-T1) after physical therapy(p<0.05). Initial Bl score, patients' attitude for physical therapy after discharge, age, and surgical operation were significantly associated with the improvement of BI score between initial and one month after discharge(T4-T1)(p<0.05). The lower initial BI score, patients' positive attitude for physical therapy after discharge, below age forty. and no surgical operation showed significantly higher improvement(p<0.05). BI score at discharge, side of hemiparesis and religion were significantly associated with the improvement of BI score between at discharge and one month after discharge(T4-T3) (p<0.05). The lower BI score at discharge. left aide of hemiparesis, with religion showed significantly higher improvement (p<0.05). Age, initial PS score were significantly associated with the improved in PS score between initial and discharge(T3-T1)(p<0.05). The higher initial PS score and below age forty showed significantly higher improvement(T3-T1)(p<0.05). Initial PS score, patient' attitude for physical therapy after discharge, age, educational level, physical therapy hour after discharge, and surgical operation were significantly associated with the improvement of PS score between initial and one month after discharge(T4-T1)(p<0.05). The higher initial PS score, patients' positive attitude for physical therapy after discharge, below age forty, higher education, the shorter physical therapy hour, and no surgical operation showed significantly higher improvement(T4-T1)(p<0.05). PS score at discharge, educational level, patient' attitude far physical therapy after discharge, physical therapy hour after discharge, and gender were significantly associated with the improvement of PS score between discharge and une month after discharge(T4-T3) (p<0.05), The higher PS non at discharge, higher education, patients' positive attitude for Physical therapy after discharge, the shorter physical therapy hour, and male showed significantly higher improvement (T4-T3)(p<0.05). In conclusion, initial BI score and age were significantly associated with BI score improvement and initial PS score, age, and educational level were also significantly associated with PS score improvement in stoke patients.

• Environmental Engineering Research
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• v.25 no.2
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• pp.178-185
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• 2020

The aim of this study is to investigate the degradation of ciprofloxacin (CIP) from its aqueous solutions via different advanced oxidation processes (AOP). The effects of persulfate (PS) concentration, pH, zinc oxide nanoparticles (ZnO-NPs) dose, initial CIP concentration, and reaction time on the degradation of CIP were studied. It was found that the sonochemical (US) degradation is a less efficient process (with removal efficiency of 36%) compared to the sono-nano-chemical (US/ZnO) process which resulted in removal efficiency of 70%. Maximum removal of 99% was obtained using the sono-nano-chemical/PS (US/ZnO/PS) process at a frequency of 60 kHz, time of 10 min, pH of 7, initial CIP concentration of 25 mg/L, and PS concentration of 476.06 mg/L. The addition of PS and ZnO-NPs to the process enhanced the rate of US degradation of CIP. In addition, the kinetic parameters for the US/ZnO/PS process were obtained by fitting the kinetic data into the pseudo-first-order and pseudo-second-order kinetic models. The kinetic data was found to fit into the pseudo-first-order kinetic model than the pseudo-second-order model. The results showed that the AOP using US/ZnO/PS is a promising technique for the treatment of ciprofloxacin containing solutions.

• Journal of Sensor Science and Technology
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• v.7 no.2
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• pp.97-102
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• 1998

Organic thin film EL devices using PPV(poly (p-phenylenevinylene)) as emitter were fabricated on various conditions and structures, their electro-optical properties were estimated. Fabricated EL devices had structures of single layer(ITO(indium tin oxide)/PPV/Mg), double layer(ITO/PVK(poly(N-vinylcarbazole))/PPV/Mg and ITO/PPV/Polymer matrix + PBD/Mg) and three layer (ITO/PVK/PPV/PS(polystyrene)+PBD(butyl-2-(4-bipheny])-5-(4-tert-butylphenyl-1,3,4-oxadiazole))/Mg), their electro-optical characteristics were compared with each other. In structure of double layer (ITO/PPV /Polymer matrix + PBD/Mg), the used polymer-matrices were PMMA(poly(methyl methacrylate), PC(polycarbonate), PS and MCH(side chain liquid crystalline homopolymer). When PS as a hole transport layer was used, the luminance characteristics on concentration of PBD was obtained. In results, current-voltage-luminance curves of fabricated devices had characteristics of tunneling effect and the device showed a stable light emitting.