• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.273-274
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• 2007

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1244-1247
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• 2007

최근 대용량 데이터 전송을 요구하는 과학기술 응용에 대한 사용량이 증대 되고 차세대 인터넷에 대한 관심과 지원이 점차 확대되고 있다. 이러한 요구를 충족하기 위해 고성능 망에서의 단대단 네트워크 성능 측정 및 진단기술이 중요시 되고 있다. 본 논문에서는 현재 존재하는 단대단 망 성능 측정 도구들을 분석하고 각 도구들의 특징을 살펴본 후 현존하는 측정 도구들의 한계점에 대해 살펴본다. 또한 이러한 분석을 바탕으로 앞으로 단대단 망 성능 측정 기술이 나아가야 할 방향에 대해 모색한다.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1031-1037
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• 2018

The formation of a complex between PVP or HPC and iodine was indicated by a red shift in the tri-iode band while PVA-iodine complex showed its characterized band around 500 nm in pure aqueous media. Addition of surfactant SDS resulted in a disapperance of the characteristic blue color of the PVA-iodine complex indicating that the complex is not formed in aqueous surfactant media. However in case of PVP or HPC, presence of the monomers of SDS favored the complex formation but in higher concentration, the micelles of SDS decreased the complex. Complexation was found to increase with increasing content of n-propanol in the system since n-propanol inhibits the formation of gels or microgels in the polymer solution. But in case of PVA-iodine complex, addition of n-propanol led to conversion of bigger polyiodides into smaller ones, which is indicative of increased intermolecular hydrogen bond interaction between propanol and PVA effecting a decrease in the PVA aggregate space.

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.77-82
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• 1999

This study was carried to investigate the characteristics of chloramination as a disinfection in drinking water distribution system. The raw water comes from midstream of Han river. In the range of pH 6~8, preformed chloramine of $Cl_2/NH_3-N$ ratio 5:1 had the HPC inactivation of more than 99% with lower pH and shorter contact time and available chloramine residual was decreased a little. In the chloramines of $Cl_2/NH_3-N$ ratio 3:1~5:1, the higher $Cl_2/NH_3-N$ ratio, the much inactivation of HPC was increased, but as contact time was longer, HPC inactivation of $Cl_2/NH_3-N$ ratio 3:1~5:1 were equaled. Bactericidal activity of three chlorine and postammoniation was influenced by free available chlorine completely and that of preammoniation was as follows : free chlorine ${\fallingdotseq}$ postammoniation>preammoniation>preformed chloramine.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.6
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• pp.527-533
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• 2018

Microorganisms detected in the biofilm not only cause secondary pollution of drinking water such as taste, odor and pathogenic disease but also increase the amount of disinfectant due to microbial regrowth during the transportation of tap water. In this work, the influence of C/N ratio in tap water on the characteristics of biofilm growth was examined. The C/N ratio of the tap water sample was controlled at 100:5, 100:10, 100:20, 100:30, and 100:40 by adding appropriate amounts of dextrose and $(NH_4)_2SO_4$. Of the five C/N ratios, heterotrophic plate counts (HPC) was highest at the ratio of 100:10. Following the initial formation in all the five experimental conditions, natural detachment of the biofilm was observed. Extracellular enzyme activity (EEA) analyses showed that the change of the EEA during the experimental period was similar to that of the HPC, demonstrating a positive correlation between HPC and EEA. For TOC concentration in the tap water sample, approximately 75% of the TOC was consumed in 7 days of the experiment and 96% in 28 days. The TOC appeared to be relatively rapidly consumed at the initial phase of the biofilm growth. Consumption pattern of the ammonia nitrogen was different from the TOC consumption pattern showing the different role of ammonia nitrogen on the growth of biofilm.

• Journal of the Korean Ceramic Society
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• v.32 no.5
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• pp.594-600
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• 1995

Spherical alumina gel powders were produced by hydrolysis of aluminum sec-butoxide (Al(sec-OC4H9)3) in a n-octanol/acetonitrile mixed solvent. The enlargement of particle size was induced by increasing HPC (hydroypropylcellulose) concentration (0.005, 0.1, and 0.05 g/ι) and emulsion-state aging time (10 min and 360 min). Mean particle sizes of dried alumina gel powders increased from 1.4 ${\mu}{\textrm}{m}$ to 3.5${\mu}{\textrm}{m}$ at 10-min emulsion-state aging time and from 1.9${\mu}{\textrm}{m}$ to 4.1${\mu}{\textrm}{m}$ at 360-min emulsion-state aging time as HPC concentration increased from 0.005 g/ι to 0.05 g/ι. At the same HPC concentration, particle size of dried alumina gel powder increased with increasing of emulsion-state aging time from 10 min to 360 min. The increase in the average particle size of dried alumina gel powder with increase in HPC concentration was interpreted as the enlargement of particles from alkoxide emulsions unprotected by HPC. The produced dried gel powder calcined at 115$0^{\circ}C$ for one hour transformed to $\alpha$-alumina.

• Journal of the Korean Ceramic Society
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• v.28 no.8
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• pp.611-618
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• 1991

In the present study adding hydroxypropyl celluose as dispersant to the ethanol solution of Zr-butoxide prior to starting the hydrolysis reaction, spherical and submicrometer sized hydrated zirconia powders were synthesized successfully. But syntesized hydrated zirconia powders were soluble considerably in ethanol used as washing medium. Washing once the powder with plenty amount of water after washing thrice it with acetone, reaction mother solution remained between the particles was effectively removed and the particles were converted to insoluble state to ethanol at the same time. As a result of such washing processes it was able to prevent the formation of polydispersed, agglomerated and multiplet particles almost always even when such concentrated solutions of Zr-n-butoxide as 0.5 M were hydrolyzed.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.2
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• pp.501-506
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• 2015

Background: To evaluate the effectiveness of the National Train-the-Trainers Program for Hospice and Palliative Care Experts (TTHPC) sponsored by the National Cancer Center of Korea between 2009 and 2012. This program was developed to improve the teaching skills of those in the field of hospice and palliative care (HPC). Materials and Methods: Training was offered in eight 1-day sessions between 2009 and 2012. The effect of the program was measured using Kirkpatrick's model of educational outcomes. First, levels 1 and 2 were evaluated immediately after the 1-day program (n=120). In 2012, the level-3 evaluation test was administered to trainers who offered at least one HPC training (n=78) as well as to their trainees (n=537). Results: The level-1 evaluation addressed participant reactions to and satisfaction with the program. Participants (n=120) were generally satisfied with the content, the method, and the overall course (mean range: 3.94-4.46 on a five-point Likert scale). The level-2 evaluation (learning) showed that participants gained knowledge and confidence related to teaching HPC (4.24 vs. 4.00). The level-3 evaluation (behavioral), which assessed trainers' application of teaching skills to HPC, showed that trainees rated the teaching methods of trainers (mean range: 4.03-4.08) more positively than did trainers (p<0.05). Female trainers were more likely than were male trainers to plan sessions in consideration of their trainees' characteristics (4.11 vs. 3.58; p<0.05), and nurse trainers were more likely than physician trainers to use a variety of instructional methods (4.05 vs. 3.36; p<0.05) Conclusions: We conducted systematic evaluations based on Kirkpatrick's model to assess the effectiveness of our train-the-trainers program. Our educational program was practical, effective, and followed by our HPC experts, who needed guidance to learn and improve their clinical teaching skills.

• Structural Engineering and Mechanics
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• v.52 no.1
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• pp.97-113
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• 2014

In the present work appropriate concrete material models have been proposed to predict drying shrinkage and specific creep of High-performance concrete (HPC) using Artificial Neural Network (ANN). The ANN models are trained, tested and validated using 106 different experimental measured set of data collected from different literatures. The developed models consist of 12 input parameters which include quantities of ingredients namely ordinary Portland cement, fly ash, silica fume, ground granulated blast-furnace slag, water, and other aggregate to cement ratio, volume to surface area ratio, compressive strength at age of loading, relative humidity, age of drying commencement and age of concrete. The Feed-forward backpropagation networks with Levenberg-Marquardt training function are chosen for proposed ANN models and same implemented on MATLAB platform. The results shows that the proposed ANN models are more rational as well as computationally more efficient to predict time-dependent properties of drying shrinkage and specific creep of HPC with high level accuracy.

• International Journal of Concrete Structures and Materials
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• v.9 no.1
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• pp.119-132
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• 2015

Electrical resistivity is an important physical property of portland cement concrete which is directly related to chloride induced corrosion process. This study examined the electrical surface resistivity (SR) and bulk electrical resistivity (BR) of concrete cylinders for various binary and ternary based high-performance concrete (HPC) mixtures from 7 to 161 days. Two different types of instruments were utilized for this investigation and they were 4 point Wenner probe meter for SR and Merlin conductivity tester for bulk resistivity measurements. Chronological development of electrical resistivity as well as correlation between two types of resistivity on several days was established for all concrete mixtures. The ratio of experimental surface resistance to bulk resistance and corresponding resistivity was computed and compared with theoretical values. Results depicted that bulk and SR are well correlated for different groups of HPC mixtures and these mixtures have attained higher range of electrical resistivity for both types of measurements. In addition, this study presents distribution of surface and bulk resistivity in different permeability classes as proposed by Florida Department of Transportation (FDOT) specification from 7 to 161 days. Furthermore, electrical resistivity data for several HPC mixtures and testing procedure provide multiple promising options for long lasting bridge decks against chloride induced corrosion due to its ease of implementation, repeatability, non-destructive nature, and low cost.