• Elastomers and Composites
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• v.56 no.4
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• pp.254-263
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• 2021

In this study, chitosan obtained after varying extents of deacetylation (i.e., 10%, 30%, and 47%) was employed to introduce antibacterial properties to chitin. The deacetylation reaction completion, wherein the amino group content of chitin was reduced, was ascertained from the FT-IR and NMR analyses. The 47%-deacetylated chitosan exhibited superior antibacterial properties against Bacillus in a disk diffusion test. To further improve these properties, chitosan derivatives were grafted by acrylic acid and acrylamide. The varying concentrations of carboxyl groups, primary amines, and -CH₂-CH₂- with increasing acrylic acid and acrylamide contents were determined by FT-IR and NMR analyses. The enhanced antibacterial properties of the chitosan derivatives, owing to the increased acrylic acid and acrylamide contents, were revealed by the disk diffusion test. In particular, the derivatives with 1.3% acrylic acid and acrylamide showed the highest antibacterial activity, the bacterial reduction rate against Staphylococcus aureus and Escherichia coli being 99.9%, as observed through the ASTM E2149 standard test.

• Journal of ILASS-Korea
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• v.24 no.3
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• pp.145-151
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• 2019

Viscoelastic fluid is used in various industrial sites because its cost reduction and environmental benefits by preventing formation of fine droplets that scattered around. However, viscoelastic fluids, unlike newtonian fluids, contain a shear thinning characteristic that decrease in viscosity as shear rate increases and elastic characteristic, making it difficult to predict spray breakup process. In this study we made three test fluids. Boger fluid with viscoelastic characteristics, and two newtonian fluids, were prepared to exclude shear thinning characteristics and study the effects of elastic characteristic only. Flow visualization, spray angle, and SMD were measured for three test fluids using laboratory scale impinging jet test apparatus. As a result, it was confirmed that Boger fluid, unlike the newtonian fluid, was not formed fine droplets that scattered around and the breakup process appeared differently. In addition, SMD was found to be large in Boger fluid, and the SMD according to pressure was confirmed that there is no significant difference.

• Journal of Environmental Science International
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• v.16 no.2
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• pp.211-218
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• 2007

The objectives of this study have been carried out to investigate the solubilization of municipal sewage sludge by single and dual frequency ultrasonic pretreatment, and the methane production characteristics of pretreated sewage sludge by specific methanogenic activity test for sewage sludge reduction. The waste activated sludge was collected from thickened tank of Suyoung sewage treatment plant in Busan city, and its concentration was adjusted to 1.0% total solids. Ultrasonic frequency was varied 15, 20, 15+20 kHz, and acoustic density was used a maximum 176W/L. The dual frequency ultrasonic pretreatment was found to be more effective than single frequency ultrasonic in the solubilization rate and methane production. The $SCOD_{Cr}/TCOD_{Cr}$, rate were 15.2%, 13.9%, 17.0% with single frequency of 15 kH2, 20 kHz, dual frequency of 15+20 kHz, respectively. The application of dual frequency ultrasound for sewage sludge pretreatment can be interest for sewage treatment plants having problems in sludge treatment and disposal.

• International Journal of Oral Biology
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• v.40 no.3
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• pp.143-146
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• 2015

The purpose of this study was to compare the effect of different methods of hand washing by counting the number of bacteria on the hand surface. Eighteen clinicians were chosen and divided into three groups, consisting of six clinicians each. Culturing of the right raw palms of all individuals was performed. Individuals in the control group washed hands for 5 seconds with antimicrobial soap. Group 1 washed their hands for 10 seconds with antimicrobial soap. Group 2 washed with an instant alcohol-based hand sanitizer. After the respective washes, re-culturing of the right raw palm was done for each member of all groups. The colony-forming units (CFU) were calculated at each time point, and the reduction rate of CFU among the three groups were statistically evaluated using student t-test. All groups showed a significant decrease in CFU, according to the time applied (P<0.01). In addition, the reduction rate of CFU between the groups were statistically evaluated with ANOVA (P<0.01). It showed statistically difference between the control group and group 1, control group and group 2. The present study confirmed that the hand washing method with antimicrobial soap for 10 seconds and hand sanitizer, including alcohol, were excellent for decreasing the number of bacteria on the hand surface.

• International Journal of Railway
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• v.2 no.3
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• pp.99-106
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• 2009

Checks and tests before putting safety facilities into service as well as the results of these tests are essential, time consuming and may show great variations between each other. Economic constraints and the increasing complexity associated with the development of computerized tools tend to limit the capacity of the classic approval process (manual or automatic). A reduction of the validation cover rate could result in practice. This is not compatible with the French national plan to renew the interlocking systems of the national network. The method and the tool presented in this paper makes it possible to formally validate new computerized systems or evolutions of existing French interlocking systems with real-time functional interpreted Petri nets. The aim of our project is to provide SNCF with a method for the formal validation of French interlocking systems. A formal proof method by assertion, which is applicable to industrial automation equipment such as interlocking systems, and which covers equally the specification and its real software implementation, is presented in this paper. With the proposed method we completely verify that the system follows all safety properties at all times and does not show superfluous conditions: it replaces all the indoor checks (not the outdoor checks). The advantages expected are a significant reduction of testing time and of the related costs, an increase of the test coverage rate, an answer to the new demand of railway infrastructure maintenance engineering to modify and validate computerized interlocking systems. Formal methods mastery by infrastructure engineers are surely a key to prove that more safety is not necessarily more expensive.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.14 no.1
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• pp.39-47
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• 2019

Objectives : The purpose of this study was to evaluate the scientific literature demonstrating the effectiveness of Chuna manual therapy (CMT) in the treatment of spinal scoliosis. Methods : A literature search was conducted using eight electronic databases to identify all randomized controlled clinical trials (RCTs) that investigated CMT as a treatment for spinal scoliosis. The Cochrane risk of bias tool was used to assess the methodological quality of each RCT. Results : Five RCTs met our inclusion criteria and were included in the analysis. These studies demonstrated positive results of CMT with respect to the reduction of Cobb's angle, vertebral rotation angle score, bending test score, and efficacy rate compared with brace treatment. Positive results were also assured, in terms of the reduction of Cobb's angle, pulmonary function, and efficacy rate when comparing CMT combined with other therapy with brace treatment, gymnastic training, or traction therapy. Conclusions : This review has identified encouraging and limited evidence of CMT for the treatment of spinal scoliosis. However, to obtain stronger evidence, without the disadvantages of study design and quality, we recommend that treatment effectiveness of CMT for spinal scoliosis is investigated further using a well-designed RCT.

• International Journal of Computer Science & Network Security
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• v.24 no.3
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• pp.182-188
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• 2024

Hardware components are an integral part of Hardware Define Radio (HDR) for seamless operations and optimal performance. On the other hand, Software Define Radio (SDR) is a program that does not rely on any hardware components for its performance. Both of the latter radio programmers utilize modulation functions to make their core components from signal processing viewpoint. The following paper concentrates on SDR based modulation and their performance under different modulations. The bit error rate (BER) of modulations such as PSK, QAM, and PSAM were used as indicators to test channel quality estimation in planar Rayleigh fading. Though it is not commonly used for channel fading, the method of the adder determines the regionally segmented channel fading. Thus, the estimation error of the channel change substantially reduces the performance of the signal, hence, proving to be an effective option. Moreover, this paper also elaborates that BER is calculated as a function of the sample size (signal length) with an average of 20 decibels. Consequently, the size of the results for different modulation schemes has been explored. The analytical results through derivations have been verified through computer simulation. The results focused on parameters of amplitude estimation error for 1dB reduction in the average signal-to-noise ratio, while the combined amplitude deviation estimation error results are obtained for a 3.5 dB reduction

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.33-43
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• 2014

Recently, the case to construct the structure on the soft clayey ground has increased and in order to the reduction of the cost of construction and maintenance on the social infrastructure facilities we have been trying to improve the soft clayey ground using the existing methods such as the pre-loading method and the vertical drain method. Like this, when various ground improvement methods are applied on the soft clayey ground, a long-term consolidation settlement will be key issue due to low permeability coefficient of cohesive soil. According to existing research results that relate to the consolidation settlement, the loading periods for existing the standard consolidation test (Oedometer test) to obtain the consolidation parameters are needed for minimum ten days or more. Therefore, in this study, the standard consolidation test (24 hours step-loading) and constant strain rate consolidation test changed by strain rate was performed using the remolded marine clay on Gwangyang bay composed of a soft clayey ground of the south-west coast. From the laboratory test results, the characteristics of compression, strain-effective stress relations by constant strain rate and the variation characteristic of the pore water pressure by different of loading speed and the relation between consolidation parameters and constant strain rate are compared and analyzed.

• Journal of Biosystems Engineering
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• v.21 no.1
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• pp.60-71
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• 1996

The purposes of this study were to develop a simulation model and to determine minimum specific airflow rate requirements for natural air drying of rough rice in Korea. A simulation model was developed considering energy and mass balances within grain bed, drying and rewetting rates, and hysterisis effect between sorption and desorption isotherms. As the results of validation test, the moisture contents predicted by the model agreed very well with the actual data. The criteria for determining minimum specific airflow rate requirements was that the top loom layer in the bin be dried to a moisture content below 16 percent wet basis with less than 0.5% drymatter decomposition. The minimum specific airflow rate requirements in 13 locations of Korea were presented based on the worst one among the past 7 to 13-year weather data. These requirements were also presented for all the combinations of three harvest dates and four harvest moisture contents. Specific airflow rate requirements seemed to be half by each 2 percent reduction in moisture content from 24 percent. As harvest date was delayed by 10 days from October 1, these requirements were reduced by about 20 to 40 percent.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.87-91
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• 2008

The study examined fire resistance of concrete followed by change of mixed rate in PP and NY composite fiber and the results were as follows. In the event of fluidity in concrete not set, plane satisfied 600±100, its target slump flow, and fluidity was reduced as organic fiber's mixed rate was increased. Air amount satisfied 3.0±1.0, its target air amount, and didn't have distinct differences in reduction and increase according to organic fiber's kind and change of its mixed rate. However, it had a tendency that fluidity was reduced as the mixed rate was increased. In characteristics of hardening concrete, the 28th day compressive strength followed by organic fiber's kind and change of its mixed rate didn't have a lot of differences and satisfied high strength scope as about 70MPa. In spalling characteristics after fire resistance test, spalling was happened in non-mixture, plane combination, and P1N0. In other combinations, spalling resistance was happened. The relic compressive strength rate was 56%, the best condition, in P3N1(PP0.03%, NY0.01% compositeness) mixing PP fiber with NY fiber at once.