• Journal of the Korean School Mathematics Society
• /
• v.11 no.4
• /
• pp.629-654
• /
• 2008

This study investigated school mathematics curriculum of the State of Georgia in the United States focused on the 'number and operation' and 'algebra' domain. On the basis of its understanding, this domain was compared and analyzed with school mathematics curriculum of Korea. In doing so, this study explored its plans and procedures and established a frame of comparison for the curriculums between the two countries. The most noticeable difference between the former and the new curriculum in mathematics for Georgia schools is the use of performance standards. A performance standard has four components: a content standard, illustrative tasks, examples of student work, and a commentary for teachers. This study focuses on the content standard and according to the results of the present study, Korea focuses on the formal and systematic mathematical knowledge on the basis of sound understanding of certain mathematical terms or concepts. On the other hand, the State of Georgia curriculum tends to deal with the content which can be understood more intuitively, flexibly, and naturally through the experience, aquisition, and furthermore interpretation based on the concrete manipulation and technological devices.

• The Research Journal of the Costume Culture
• /
• v.24 no.2
• /
• pp.180-197
• /
• 2016

The purpose of this study is to create knit ruffles that represent the aesthetic and artistic values of painted works of art that rhythmically express flower petals and add an artistic impression on the knit ruffle designs. This study is based on the artistic life of Georgia O'Keeffe and changes in her artistic background, and the world of paintings. The relevant data was gathered from domestic and foreign references, academic journals, and the internet. The characteristics of Georgia O'Keeffe paintings were examined. Her paintings typically include a series of various motifs, symmetry, balance, and harmony of detailed realistic expressions and abstract elements, repetition, and the principles of contrast and emphasis in shaping. The decoration techniques used on fabrics were applied using the knitting machine which controls the tension to develop a variety of textures, apart from the previous standardized knit textures, through various knitting techniques. A gradation effect was then applied by piece-dyeing the knitted materials in various colors to express asimilarity to the original colors in O'Keeffe's works with delicate color expressions. After the piece-dyeing, the decorative knitted materials were trimmed on a model to re-create the natural curves of flower petals. This study aims to converge works of art with fashion designs to develop various creative knitted fashion and to impart an artistic sense in the fashion design industry.

• Communications for Statistical Applications and Methods
• /
• v.24 no.3
• /
• pp.241-254
• /
• 2017

Drawing a sample can be costly or time consuming in some studies. However, it may be possible to rank the sampling units according to some baseline auxiliary covariates, which are easily obtainable, and/or cost efficient. Ranked set sampling (RSS) is a method to achieve this goal. In this paper, we propose a modified approach of the RSS method to allocate units into an experimental study that compares L groups. Computer simulation estimates the empirical nominal values and the empirical power values for the test procedure of comparing L different groups using modified RSS based on the regression approach in analysis of covariance (ANCOVA) models. A comparison to simple random sampling (SRS) is made to demonstrate efficiency. The results indicate that the required sample sizes for a given precision are smaller under RSS than under SRS. The modified RSS protocol was applied to an experimental study. The experimental study was designed to obtain a better understanding of the pathways by which positive experiences (i.e., goal completion) contribute to higher levels of happiness, well-being, and life satisfaction. The use of the RSS method resulted in a cost reduction associated with smaller sample size without losing the precision of the analysis.

• Imaging Science in Dentistry
• /
• v.44 no.2
• /
• pp.149-154
• /
• 2014

Purpose: This study assessed the effectiveness of three antimicrobial mouthrinses in reducing microbial growth on photostimulable phosphor (PSP) plates. Materials and Methods: Prior to performing a full-mouth radiographic survey (FMX), subjects were asked to rinse with one of the three test rinses ($Listerine^{(R)}$, $Decapinol^{(R)}$, or chlorhexidine oral rinse 0.12%) or to refrain from rinsing. Four PSP plates were sampled from each FMX through collection into sterile containers upon exiting the scanner. Flame-sterilized forceps were used to transfer the PSP plates onto blood agar plates (5% sheep blood agar). The blood agar plates were incubated at $37^{\circ}C$ for up to 72 h. An environmental control blood agar plate was incubated with each batch. Additionally, for control, 25 gas-sterilized PSP plates were plated onto blood agar and analyzed. Results: The mean number of bacterial colonies per plate was the lowest in the chlorhexidine group, followed by the Decapinol, Listerine, and the no rinse negative control groups. Only the chlorhexidine and Listerine groups were significantly different (p=0.005). No growth was observed for the 25 gas-sterilized control plates or the environmental control blood agar plates. Conclusion: The mean number of bacterial colonies was the lowest in the chlorhexidine group, followed by the Decapinol, Listerine, and the no rinse groups. Nonetheless, a statistically significant difference was found only in the case of Listerine. Additional research is needed to test whether a higher concentration (0.2%) or longer exposure period (two consecutive 30 s rinse periods) would be helpful in reducing PSP plate contamination further with chlorhexidine.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.5
• /
• pp.391-403
• /
• 2013

Propeller aircraft propelled by an electric propulsion system is gaining a renewed interest because of ever-increasing environmental concern on harmful emissions emitted from conventional jet engines and national energy security. Traditional aircraft sizing methods are not readily applicable to electric propulsion aircraft that utilize a variety of alternative energy sources and power generation systems. This study showcases an electric propulsion aircraft sizing exercise based on a generalized, power based sizing method. A general aviation aircraft is propelled by an electric propulsion system that comprises of a propeller, a high temperature super conducting motor, a Proton Exchange Membrance(PEM) fuel cell system fuelled with hydrogen, and power conditioning equipment. In order to assess the impact of technology progression, aircraft sizing was conducted for two different sets of technology assumptions for electric components, and the results were compared with conventional baseline aircraft.

• Journal of Electrochemical Science and Technology
• /
• v.1 no.1
• /
• pp.50-56
• /
• 2010

$La_{0.6}Sr_{0.4}Co_{0.2}Fe_{0.8}O_{3-\delta}$ (LSCF) powders with different particle sizes, synthesized through a citrate complexation method and a gel-casting technique, are used to fabricate porous LSCF cathodes with graded microstructures via tape casting. To create porous electrodes with desired porosity and pore structures, graphite and starch are used as pore former for different layers of the graded cathode. Examination of the microstructures of the as-prepared LSCF cathode using an SEM revealed that both grain size and porosity changed gradually from the catalytically active layer (near the electrodeelectrolyte interface) to the current collection layer (near the electrode-interconnect interface). Impedance analysis showed that a 3-layer LSCF cathode with graded microstructures exhibited much-improved performance compared to that of a single-layer LSCF cathode, corresponding to interfacial resistance of 0.053, 0.11, and 0.27 $\Omega{\cdot}cm^2$ at 800, 750, and $700^{\circ}C$ respectively.

• Transactions on Electrical and Electronic Materials
• /
• v.7 no.5
• /
• pp.217-223
• /
• 2006

When only partial information is available about equipment failures (installation date and amount, as well as failure and replacement rates), data on sufficiently large number of yearly populations of the components can be combined, and estimation of model parameters may be possible. The parametric models may then be used for forecasting of the system's short term future failure and for formulation of replacement strategies. We employ the Weibull distribution and show how we estimate its parameters from past failure data. Using Monte Carlo simulations, it is possible to assess confidence ranges of the forecasted component performance data.

• ETRI Journal
• /
• v.23 no.1
• /
• pp.23-32
• /
• 2001

Examination of the statistical variation of integrated passive components is crucial for designing and characterizing the performance of multichip module (MCM) substrates. In this paper, the statistical analysis of parallel plate capacitors with gridded plates manufactured in a multilayer low temperature cofired ceramic (LTCC) process is presented. A set of integrated capacitor structures is fabricated, and their scattering parameters are measured for a range of frequencies from 50 MHz to 5 GHz. Using optimized equivalent circuits obtained from HSPICE, mean and absolute deviation is calculated for each component of each device model. Monte Carlo Analysis for the capacitor structures is then performed using HSPICE. Using a comparison of the Monte Carlo results and measured data, it is determined that even a small number of sample structures, the statistical variation of the component values provides an accurate representation of the overall capacitor performance.

• Journal of the Korean School Mathematics Society
• /
• v.1 no.1
• /
• pp.89-96
• /
• 1998

The purpose of this paper was to introduce 'The Third International Mathematics and Science Study'(TIMSS) to the mathematics education society in Korea, and to address current discussion about the TIMSS from the view of three Korean authors who are currently enrolled in an American university. This paper consisted of three parts: (1) The structure and organization of the TIMSS, (2) The analyses on test items from three populations of student groups, curricula and textbooks, questionnaires from students and teachers, video study, and case studies, (3) The discussion of various perspectives for mathematics education in Korea. The authors pointed out that the TIMSS was not just an international comparison study designed for ranking each of the 41 participating countries, but a study providing some insights for Korean mathematics education.

• Journal of information and communication convergence engineering
• /
• v.8 no.3
• /
• pp.281-288
• /
• 2010

This paper investigates the performance of IEEE 802.11p wireless access in vehicular environments (WAVE) system in small-scale fading models reported by Georgia Institute of Technology (Georgia Tech). We redesign the small-scale fading models to be applied to the computer simulation and develop the IEEE 802.11p WAVE physical layer simulator to provide the bit error rate and packet error rate performances. Moreover, a new channel estimator using decision directed channel estimation and linear minimum mean square error smoothing is proposed in order to improve the performance of the conventional least square channel estimator using two identical long training symbols. The simulation results are satisfactorily coincident with the scenarios of Georgia Tech report, and the proposed channel estimator significantly outperforms the conventional channel estimator.