• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1115-1122
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• 2011

Reinforced-Roadbed materials are usually composed of crushed stones. Repeated load application can induce deformation in the reinforced-roadbed layer so that it causes irregularity of track. Thus it is important to develop a prediction model of elastic modulus based on stress-strain relation under repeatitive load in order to investigate behavior of reinforced roadbed. The prediction model of elastic modulus of the material can be obtained from repeated triaxial test. However, a proper size of the sample for the test must be used. In this study, a large repeatitive triaxial test apparatus with the sample size of diameter of 30 cm and height of 60cm was adapted for performing test of the crushed stone reinforced-roadbed considering large particle size to get resilient modulus Mr. The obtained resilient modulus was compared to shear modulus obtained from mid size resonant column test. The sample size effect is somewhat large enough so that it is required to design a scale factor based on similarity law in order to use smaller samples for getting elastic modulus of the crushed stone reinforced-roadbed material. A scale factor could be obtained from this study.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.11a
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• pp.226-227
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• 2014

We demonstrate nanoscale local anodic oxidation (LAO) patterning on few layer graphene using atomic force microscope (AFM) at room temperature and normal atmosphere. We focus on the humidity dependency in nanoscale oxidation of graphene. The relationship between the oxidation size and the AFM setting values, such as set point, tip speed, and humidity are observed. By changing these values, proper parameters were found to produce features on demand size. This technique provides an easy way to form graphene oxide lithography without any chemical resists. We have obtained oxidation size down to 50-nm with 6-nm-height oxide barrier line with $0.1{\mu}m/s$ tip scanning speed and micrometer size symbols on a graphene flake. We attribute the bumps to local anodic oxidation on graphene surface and combination of oxygen ions into the graphene lattice.

• Korean Journal of Veterinary Research
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• v.48 no.3
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• pp.357-361
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• 2008

Although power analysis is of important tool of research, investigators in veterinary medicine are unaware of the concepts of the statistical power. Two types of error occur in classical hypothesis testing and, those errors should be avoided, if possible. Since power is highly dependent on the sample size, whenever declaring non-statistically significant result they should consider the potential for committing a Type II error in their studies, which refers to the probability of falsely stating that two treatments are equivalent despite true difference between them. Also, sample size determination is one of the most important tasks facing the researcher when planning a diagnostic study, and provides valuable information on the characteristics of a test performance. This type of analysis forms the basis for proper interpretation of test results. The aim of this article was to re-evaluate some selected studies on diagnostic test reported in the domestic veterinary publications to determine the power and necessary sample size for inequality testing to ensure the desired power. Power calculations were illustrated using real-life examples of comparison of a new test and a reference test for detecting antibodies of various animal diseases. Factors affecting to the power were also discussed.

• Fashion & Textile Research Journal
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• v.11 no.5
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• pp.771-778
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• 2009

There may be some problems in size fitness for ready-made-clothes purchasers with fatty body shape especially for them with abdominal obesity. The purpose of this study was to improve the wearing comfort of Middle-aged women slacks by setting grading points and developing grading rules proper to the abdominal obesity. The subjects in this study was over $25kg/m^2$ of the BMI, over 85cm of waist, and over 0.8 of WHR. A total of 176 Middle-aged women satisfyingthem were enrolled. The results of this study are as follows: (1) The majority segment is 85-94 size accounting for the 11.36% of subjects. (2) The measurements on 11 size from three groups after drawing slacks pattern on them revealed that the changed values of slacks front and back on the grading point marked are differ, indicating that it is needed to apply body shape and age specific grading rule. (3) The evaluation on the appearance for wearing slacks showed relatively high score, indicating that the grading between sizes within each group was effective. The studies on the body size distribution on each obesity pattern and on the setting size system reflecting characteristics of each body shape should be performed continuously.

• Journal of Powder Materials
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• v.20 no.6
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• pp.479-486
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• 2013

In the present work, physicochemical treatments were introduced for de-aggregation and stable dispersion of detonation nanodiamonds (DND) in polar solvents. The DNDs in water exhibited a particle size of 138 nm and high dispersion stability without particular treatment. However, the DNDs in ethanol were severely aggregated to several micrometers in size and showed poor dispersion stability with time. To break down aggregates of DNDs and enhance the dispersion stability of them in ethanol, mechanical force and chemical surfactant were introduced as functions of zirconia ball size, kind of surfactant and amount of surfactant added. From the analyses of average particle size and Turbiscan results, it was suggested that the size of DNDs in ethanol can be reduced by only mechanical force; however, the DNDs were re-aggregated due to high surface activity. The long-term dispersion stability can be achieved by applying mechanical force to break down the aggregates of DNDs and by preventing re-aggregation of them using proper surfactant.

• Journal of Pharmaceutical Investigation
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• v.28 no.4
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• pp.249-255
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• 1998

Solid Lipid Nanoparticle(SLN), one of the colloidal carrier systems, has many advantages such as good biocompatibility, low toxicity and stability. In this paper, the effects of drug lipophilicity and surfactant on the drug loading capacity, particle size and drug release profile were examined. SLNs were prepared by homogenization of melted lipid dispersed in an aqueous surfactant solution. Ketoprofen, ibuprofen and pranoprofen were used as model drugs and tweens and poloxamers were tested for the effect of surfactant. Mean particle size of prepared SLNs was ranged from 100 to 150nm. The drug loading capacity was improved with the most lipophilic drug and low concentration of surfactant. Particle size and polydispersity of SLNs were changed according to the used lipid and surfactant. The rates of drug release were controlled by the loading drug and surfactant concentration. SLN system with effective drug loading efficiency and proper particle size for the intravenous or oral formulation can be prepared by selecting optimum drug and surfactant.

• Transactions on Electrical and Electronic Materials
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• v.7 no.4
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• pp.167-172
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• 2006

Submicron colloidal silica coated with ceria were prepared by mixing of silica and nano ceria particles and modified by hydrothermal reaction. The polishing efficiency of the ceria coated silica slurry was tested over oxide film on silicon wafer. By changing the polishing pressure in the range of $140{\sim}420g/cm^2$ with the ceria coated silica slurries in $100{\sim}300nm$, rates, WIWNU and friction force were measured. The removal rate was in the order of 200, 100, and 300 nm size silica coated with ceria. It was known that the smaller particle size gives the higher removal rate with higher contact area in Cu slurry. In the case of oxide film, the indentation volume as well as contact area gives effect on the removal rate depending on the size of abrasives. The indentation volume increase with the size of abrasive particles, which results to higher removal rate. The highest removal rate in 200 nm silica core coated with ceria is discussed as proper combination of indentation and contact area effect.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.1
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• pp.27-33
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• 1975

The required minimum size of character diode matrix of Korean letters is estimated from the topological complexity of letter structure. The OR aombination of three letter boards (diode matrice) gives all possible Hangout whole letters in proper traditional combined form with minimum required discernibility. Two forms of first consonants (centre located ones for horizontal vowels and leftward displaced ones for vertical and composed vowels) are switched by only 1 bit of the vowel code. The vowel pattern length is modified by again the last four bits of the code. A new 15bit sized inner code is proposed which permits considerably small sized decoding mechanism.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.1
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• pp.143-148
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• 2007

The objective of this study was to investigate the proper conditions of calcination and calcium extraction from powdered oyster shell. The physical characteristics such as particle size distribution, surface morphology, and thermal gravity were examined. The following result were obtained. As the powdered oyster shell was ignited in high temperature of $650^{\circ}C$ to $950^{\circ}C$, the calcination reactions was effectively progressed. The amount of weight loss during calcination would be matched with the generation of carbon dioxide gas. In the calcination of powdered oyster shell, the amount of weight loss increased according to the increased of calcination temperature and the decrease of mean particle size. It was founded that the proper temperature and retention time of calcination was $850^{\circ}C$ and 40 minute. In the extraction of calcium into liquid form using acid addition, the calcination oyster shell was more effective than the non-calcinated shell. The liquid calcium extraction technique using the calcinated oyster shell needed more researches considering cost evaluation.

• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.7-18
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• 2009

In 2008, there are 135 service areas, which provide for drivers to convenience on expressways. But there are some problems on parking capacity, because it is failed to calculate the appropriate parking lots of the service area. The fundamental problem is that the size of parking lots is calculated by simple value; despite there are various factors of utilization, congestion, and turnover. This paper describes a study on proper coefficient for calculating the appropriate service area, considering the characteristics of drivers' behavior. We conducted statistical analysis with the surveyed data in "Status of the expressway facilities in 2004." Analysis results show there are some difference by day and night, and vehicle type with the factor of utilization, congestion, and turnover, and there are different usages according to expressway route. The results indicate that the usage of a service area have different characteristics by time and space, and vehicle type.