• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.309-314
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• 2003

In order to find out the microscopic environmental information on the nonionic reverse micelle of Triton X-100/n-hexanol/water in cyclohexane, an absorption and fluorescence spectroscopic study has been conducted using a methylene blue(MB). The information on the microscopic states of water in the polar core of the reverse micelle has been found by investigating complex formation and solvatochromic behavior between MB and Triton X-100. As a result, it was found that there exist three states in the polar core of the reverse micelle. The measured values of $W(=[H_2O]/[Surf])$ for the three states of water are 0.71, 4.98, and 7.26, and the corresponding lifetimes of MB are $15.45 ns{\pm}0.56$, $12.27 ns{\pm}0.79$, and $8.28 ns{\pm}0.82$, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.308-316
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• 2015

In this paper, we carried out performance comparison of four routing protocols that had been proposed for mobile ad hoc networks using the NS-3 network simulator. Those four routing protocols consist of two proactive routing protocols, DSDV(destination-sequenced distance vector) and OLSR(optimized link state routing), and two reactive routing protocols, AODV(ad-hoc on-demand distance vector) and DSR(dynamic source routing). Two performance metrics, system throughput and packet delivery ratio, are adopted and performance evaluation was carried out in a square communication area where each communicating mobile node moves independently. Numerical results show that the AODV routing protocol provides the best performance among those four routing protocols.

• Structural Engineering and Mechanics
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• v.82 no.3
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• pp.295-312
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• 2022

This study investigates the effects of nano silica (NS) and micro steel fiber on the properties of ultra-high-performance concrete (UHPC). The experimental consists of three groups, each one with five percentages of NS content (0%, 2%, 4%, 6% and 8%) in addition to the 20% silica fume and 20% quartz powder proportioned according to the weight of cement added to the mixtures. In addition, three percentages of micro steel fibers (0%, 1% and 2%) were considered. Different mixtures with varying percentages of NS and micro steel fibers were prepared to set the water-to-binder ratio, such as 0.16% and 1.8% superplasticizer proportioned according the weight of the binder materials. The fresh properties, mechanical properties and elevated temperatures of the mixtures were calculated. Then, the results from the microstructure analyses were compared with that of the reference mixtureand it was found that 6% replacement of cement with NS was optimum replacement level. When the NS content was increased from 0% to 6%, the air content and permeability of the mixture decreased by 35% and 39%, the compressive and tensile strength improved by 21% and 18% and the flexural strength and modulus of elasticity increased by 20% and 11.5%, respectively. However, the effect of micro steel fibres on the compressive strength was inconclusive. The overall results indicate that micro steel fibres have the potential to improve the tensile strength, flexure strength and modulus of elasticity of the UHPC. The use of 6% NS together with 1% micro-steel fiber increased the concrete strength and reduce the cost of concrete mix.

• BMB Reports
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• v.38 no.1
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• pp.104-110
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• 2005

We extended the measurable time scale of DNA dynamics to microsecond using $[Ru(phen)_2(dppz)]^{2+}$ (phen = 1,10-phenanthroline, dppz = dipyrido[3,2-a:2',3'-c]phenazine) (RuPD), which displays a mean lifetime near 500 ns. To evaluate the usefulness of this luminophore (RuPD) for probing nucleic acid dynamics, its intensity and anisotropy decays when intercalated into supercoiled and linear pBluescript (pBS) II SK(+) phagemids were examined using frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. The mean lifetime for the supercoiled phagemids (< $\tau$ > = 489.7 ns) was somewhat shorter than that for the linear phagemids (< $\tau$ > = 506.4 ns), suggesting a more efficient shielding from water by the linear phagemids. The anisotropy decay data also showed somewhat shorter slow rotational correlation times for supercoiled phagemids (997.2 ns) than for the linear phagemids (1175.6 ns). The slow and fast rotational correlation times appear to be consistent with the bending and torsional motions of the phagemids, respectively. These results indicate that RuPD can have applications in studies of both bending and torsional dynamics of nucleic acids.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.11a
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• pp.136-140
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• 1992

The purpose of this research is to develop the lithium secondary battery. This paper describes the preparation, electrochemical properties of nontstoichiometric(NS)-$V_6O_{13}$ and characteristics of Li/$V_6O_{13}$ secondary battery. NS-$V_6O_{13}$ was prepared by thermal decomposition of $NH_4VO_3$ under Ar stream of 140ml/min~180ml/min flow rate. And then, this NS-$V_6O_{13}$ was used for cathode active material. Cathode sheet was prepared by compressing the composite of NS-$V_6O_{13}$, acetylene black(A.B) and teflon emulsion (T.E). Characteristics of the test cell are summarised as follows. Oxidation capacity of NS-$V_6O_{13}$ was about 20% less than its reduction capacity. A part of NS-$V_6O_{13}$ cathode active material showed irreversible reaction in early charge-discharge cycle. This phenomena seems to be caused by irreversible incoporation/discoporation of lithium cation to/from NS-$V_6O_{13}$ host. Discharge characteristics curve of Li/$V_6O_{13}$ cell showed 4 potential plateaus. Charge-discharge capacity was declined in the beginning of cycling and slowly increased in company with increasing of coulombic efficiency. Energy density per weight of $V_6O_{13}$ cathode material was as high as 522Wh/kg~765Wh/kg.

• Advances in nano research
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• v.15 no.5
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• pp.467-484
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• 2023

Despite the significant features of fiber-reinforced cementitious composites (FRCCs), including better mechanical, fractural, and durability performance, their high content of cement has restricted their use in the construction industry. Although ground granulated blast furnace slag (GGBFS) is considered the main supplementary cementitious material, its slow pozzolanic reaction stands against its application. The addition of nano-sized mineral modifiers, including nano-silica (NS), is an alternative to address the drawbacks of using GGBFS. The main object of this empirical and numerical research is to examine the effect of NS on the strain-hardening behavior of cementitious composites; ten mixes were designed, and five levels of NS were considered. This study proposes a new method, using a four-point bending test to assess the use of nano-silica (NS) on the flexural behavior, first cracking strength, fracture energy, and micromechanical parameters including interfacial friction bond strength and maximum bridging stress. Digital image correlation (DIC) was used for monitoring the initiation and propagation of the cracks. In addition, to attain a deep comprehension of fiber/matrix interaction, scanning electron microscope (SEM) analysis was used. It was discovered that using nano-silica (NS) in cementitious materials results in an enhancement in the matrix toughness, which prevents multiple cracking and, therefore, strain-hardening. In addition, adding NS enhanced the interfacial transition zone between matrix and fiber, leading to a higher interfacial friction bond strength, which helps multiple cracking in the composite due to the hydrophobic nature of polypropylene (PP) fibers. The findings of this research provide insight into finding the optimum percent of NS in which both ductility and high tensile strength of the composites would be satisfied. As a concluding remark, a new criterion is proposed, showing that the optimum value of nano-silica is 2%. The findings and proposed method of this study can facilitate the design and utilization of green cementitious composites in structures.

• Journal of Acupuncture Research
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• v.25 no.6
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• pp.153-161
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• 2008

Objectives : This study was designed to find out whether normal saline(NS) acupuncture is able to be constituted as an appropriate control group for Cervi Cornu Parvum herbal acupuncture(CC). Methods : NS and CC were injected into Quchi($LI_{11}$) of the subjects. The subjects completed a questionnaire rating the intensity of 21 kinds of acupuncture sensation(hurting, penetrating, sharp, aching, intense, spreading, radiating, tingling, pricking, stinging, pulling, heavy, dull, numb, electric, shocking, hot, burning, cool, pulsing, and throbbing) and side effects. We compared subjective evaluations of acupuncture sensation and side effects between two groups. Results : As for CC most of the acupuncture sensation items were not significantly different from NS especially in less acupuncture-experienced subjects(average 2, below 10 time experiences) rather than more acupuncture-experienced subjects(above 10 time experiences). Conclusions : We found that NS might be an appropriate placebo herbal acupuncture for CC in small amount of acupuncture-experienced subjects. Further study is needed for new placebo herbal acupuncture for CC in more acupuncture-experienced subjects.

• Journal of Bio-Environment Control
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• v.25 no.3
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• pp.162-167
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• 2016

This study was carried out to investigate proper stem cutting position and air temperature to regenerate roots from cuttings of bitter gourd. 'NS454' (NS) and 'Dragon' (DR) cultivars were tested and the cutting position was cut at the 3rd node in the stem (treatment I) and cut at the central part (stem segment) between 3rd leaf and 4th leaf in the stem (treatment II). The air temperature was maintained at 18, 23, 28 and $35^{\circ}C$ in the growth chambers, respectively. The photosynthetic photon flux at the ground of a chamber was maintained in approximately $150-200{\mu}mol\;m^{-2}s^{-1}$ during the 16-hour photoperiod. The relative humidity in the chambers was maintained over 85%. After 10 days of cuttings, regardless of cutting position, DR and NS cultivars showed 100% the survival rate in the $18^{\circ}C$ or $23^{\circ}C$ treatments, however, most of plants $18^{\circ}C$ treatment had not rooting. In the $28^{\circ}C$ treatment, regardless of cutting position, DR and NS cultivars showed 100% of the rooting rate. In the $23^{\circ}C$ treatment, for DR cultivar, the node cutting showed 90% of rooting rate and the stem segment cutting showed 40% rooting rate. For NS cultivar, the node cutting showed 50% of rooting rate and the stem segment cutting showed 40% rooting rate. DR and NS cultivars have high rooting rate, while the rooting rate remarkably decreased in the $35^{\circ}C$ treatment. For DR cultivar, the stem segment cutting showed 5.3 of the highest rooting number and the node cutting showed 2.7 rooting number in the $28^{\circ}C$ treatment. NS cultivar was not significantly different the rooting regardless of cutting position. The results suggested that cutting at the stem segment cutting of bitter gourd is an effective cutting method for increasing survival rate and the air temperature should be maintained at $28^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.5
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• pp.556-561
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• 2014

We applied a combination of most probable number-polymerase chain reaction (MPN-PCR) methods using a PCR procedure targeting the H-NS (VP1133) gene to detect Vibrio parahaemolyticus presence and density in seawater as well as within short-necked clam Ruditapes philippinarum tissues collected from Gomso Bay, Korea. In 30 seawater samples, V. parahaemolyticus levels ranged from less than 1.8 to $1.1{\times}10^3MPN/100mL$, and samples from August showed higher than those from other months. Furthermore, the levels of V. parahaemolyticus in six short-necked clam samples ranged from $7.8{\times}10^2$ to $2.1{\times}10^3MPN/100g$, approximately 2.5 times higher than in seawater samples from the corresponding month. Our results provide data on V. parahaemolyticus contamination in seawater and short-necked clam tissues, and help to improve quantitative methods of assessing V. parahaemolytcius levels.

• Laser Solutions
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• v.17 no.4
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• pp.7-13
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• 2014

In this work, the application of laser induced breakdown spectroscopy (LIBS) for the composition analysis of thin $Cu(In,Ga)Se_2$ (CIGS) solar cell films ($1-2{\mu}m$ thickness) is reported. For the ablation of CIGS films, femtosecond (fs) laser (wavelength = 343nm, pulse width = 500fs) and nanosecond (ns) laser (wavelength = 266nm, pulse width = 5ns) were used under atmospheric environment. The emission spectra were detected with an intensified charge coupled device (ICCD) spectrometer and multichannel CCD spectrometer for fs-LIBS and ns-LIBS, respectively. The calibration curves for fs-LIBS and ns-LIBS intensity ratios of Ga/Cu, In/Cu, and Ga/In were generated with respect to the concentration ratios measured by inductively coupled plasma optical emission spectrometry (ICP-OES).