• Korean Journal of Child Studies
• /
• v.37 no.3
• /
• pp.69-82
• /
• 2016

Objective: This study aimed to explore early childhood educators' anxiety regarding science education via Q-methodology. Methods: As the first step, 268 Q samples were collected from resources such as books and research papers related to science education for young children. Through five stages of excluding and modifying, a set of 33 Q statements was finalized. The P sample consisted of 40 early childhood educators and was based on educational levels, years of teaching experiences and types of centers. The collected data were analyzed using QUANL statistical program. Results: The results of this study indicate that science anxiety among early childhood educators are classified into four types, explaining 45.13% of the total variance. Conclusion: We conclude that early childhood educators' science anxiety stems from "preparing educational environment and materials," "instructional methods focused on process and scientific inquiry skills," "lack of understanding regarding early childhood science education," and "simple science avoidance."

• Communications for Statistical Applications and Methods
• /
• v.4 no.1
• /
• pp.243-254
• /
• 1997

특정분포에 대한 P-P plot과 Q-Q plot의 특징을 분석하고 두 가지 그래프 사이의 관계를 비교해 보았다. NTV의 본질적인 특징을 알아보고 각 특정분포에 대한 NTV plot의 특징을 분석했다. 전형적인 bimodal 분포가 나타날 때 P-P 혹은 Q-Q plot은 뚜렷한 break-point를 갖는다는 것을 알아보고, 단지 skewed된 분포나 skewed된 것처럼 보이는 bimodal 분포 사이에서 발생하는 판단의 어려움에 대하여 여러 plot고찰해 보았다.

• Communications for Statistical Applications and Methods
• /
• v.5 no.1
• /
• pp.205-215
• /
• 1998

정규분포에 관한 검정에 있어서 P-P 플롯과 Q-Q 플롯의 가시적인 변동을 이용한 통계량을 제시하고 이 통계량들과 Shapiro-Wilk의 W 통계량과의 비교를 정확도(accuracy)의 측면을 고려하여 실시하였다. 또한, 의학이나 임상에서 척도의 우수성을 검정하기 위해 많이 사용하는 Receiver Operating Characteristic (ROC) 분석 기법을 이용하여 제시된 통계량들에 관한 Power와 Accuracy는 물론 Best Cut-Off 측면에서의 효율성을 검정하였다.

• Journal of Power Electronics
• /
• v.8 no.1
• /
• pp.91-100
• /
• 2008

The d-q harmonic detecting algorithms are dominant methods to generate current references for active power filters (APF). They are often implemented in the synchronous frame and time domain. This paper researches the frequency characteristics of d-q synchronous transformations, which are closely related to the analysis and design issues of control system. Intuitively, the synchronous transformation is explained with amplitude modulation (AM) in this paper. Then, the synchronous filter is proven to be a time-invariant and linear system, and its transfer function matrix is derived in the stationary frames. These frequency-domain models imply that the synchronous transformation has an equivalent effect of frequency transformation. It is because of this feature, the d-q method achieves band-pass characteristics with the low pass filters in the synchronous frame at run time. To simplify these analytical models, an instantaneous positive-negative sequence frame is proposed as expansion of traditional symmetrical components theory. Furthermore, the synchronous filter is compared with the traditional bind-pass filters based on these frequency-domain analytical models. The d-q harmonic detection methods are also improved to eliminate the inherent coupling effect of synchronous transformation. Typical examples are given to verify previous analysis and comparison. Simulation and experimental results are also provided for verification.

• Journal of Sensor Science and Technology
• /
• v.33 no.1
• /
• pp.1-6
• /
• 2024

This study aims to suggest the partition ratio (Q-factor) of healthy Koreans and the comparison results of breath alcohol concentration (BAC) measurements using two methods (photoacoustic and electrochemical methods) for developing breath alcohol ignition interlock devices (BAIIDs). Given the relationship between BACs and BrACs and the Q-factor, the alcohol metabolism of healthy Koreans (96 males and 91 females) is revealed for understanding the digestion of alcohol and surveying the fundamental data of alcohol-related problems, CO₂ concentrations vs. alcohol concentrations, and the performance of alcohol sensors in the marketplace. The average Q-factor of healthy Korean males and females are 1,913 (95% confidence interval from 1,889-1,937) and 1,991 (95% confidence interval from 1,945-2,036). Photoacoustic measurements could be applied to predict the BACs of drinkers, which is confirmed by the Bland-Altman plots presented in this study. The biases based on the partition ratios (Q=1,913 and Q=1,991) in the Bland-Altman plots were -0.0004% (95% CI from -0.0011 to +0.0003% for males) and -0.0017% (95% CI from -0.020 to +0.017% for females).

• Geomechanics and Engineering
• /
• v.30 no.5
• /
• pp.449-460
• /
• 2022

Safe underground construction in a rock mass requires adequate ground investigation and effective determination of rock conditions. The estimation of rock mass behavior is difficult, because rock masses are innately anisotropic and heterogeneous at different scales and are affected by various environmental factors. Quantitative rock mass classification systems, such as the Q-system and rock mass rating, are widely used for characterization and engineering design. The measurement of rock classification parameters is subjective and can vary among observers, resulting in questionable accuracy. Geophysical investigation methods, such as seismic surveys, have also been used for ground characterization. Torsional shear wave propagation characteristics in cylindrical rods are equal to that in an infinite media. A probabilistic quantitative relationship between the Q-value and shear wave velocity is thus investigated considering long-wavelength wave propagation in equivalent continuum jointed rock masses. Individual Q-system parameters are correlated with stress-dependent shear wave velocities in jointed rocks using experimental and numerical methods. The relationship between the Q-value and the shear wave velocity is normalized using a defined reference condition. This relationship is further improved using probabilistic analysis to remove unrealistic data and to suggest a range of Q-values for a given wave velocity. The proposed probabilistic Q-value estimation is then compared with field measurements and cross-hole seismic test data to verify its applicability.

• Journal of KIISE:Databases
• /
• v.33 no.6
• /
• pp.644-653
• /
• 2006

This paper analyzes the properties of user query for stock investment recommendation, and defines the 'following relation', which is a new relation between two queries. A following relation between two queries $Q_1,\;Q_2$ and a recommendation value X means 'If the recommendation value of a preceding Query $Q_1$ is X, then a following query $Q_2$ always has X as its recommendation value'. If there exists a following relation between $Q_1\;and\;Q_2$, the recommendation value of $Q_2$ is decided immediately by that of $Q_1$, therefore we can eliminate the running process for $Q_2$. We suggest two methods in this paper. The former method analyzes all the following relations among user queries and represents them as a graph. The latter searches the graph and decides the order of queries to be processed, in order to make the number of eliminated query-running process maximized. When we apply the suggested procedures that use the following relation, most of user queries do not need to be processed directly, hence the performance of running overall queries is greatly improved. We examined the superiority of the suggested methods through experiments using real stock market data. According to the results of our experiments, overall query processing time has reduced less than 10% with our proposed methods, compared to the traditional procedure.

• Communications of the Korean Mathematical Society
• /
• v.25 no.4
• /
• pp.655-669
• /
• 2010

In this paper we propose new primal-dual interior point methods (IPMs) for $P_*(\kappa)$ linear complementarity problems (LCPs) and analyze the iteration complexity of the algorithm. New search directions and proximity measures are defined based on a class of kernel functions, $\psi(t)=\frac{t^2-1}{2}-{\int}^t_1e{^{q(\frac{1}{\xi}-1)}d{\xi}$, $q\;{\geq}\;1$. If a strictly feasible starting point is available and the parameter $q\;=\;\log\;\(1+a{\sqrt{\frac{2{\tau}+2{\sqrt{2n{\tau}}+{\theta}n}}{1-{\theta}}\)$, where $a\;=\;1\;+\;\frac{1}{\sqrt{1+2{\kappa}}}$, then new large-update primal-dual interior point algorithms have $O((1\;+\;2{\kappa})\sqrt{n}log\;n\;log\;{\frac{n}{\varepsilon}})$ iteration complexity which is the best known result for this method. For small-update methods, we have $O((1\;+\;2{\kappa})q{\sqrt{qn}}log\;{\frac{n}{\varepsilon}})$ iteration complexity.

• Korean Journal of Mathematics
• /
• v.24 no.4
• /
• pp.681-691
• /
• 2016

In this note, we consider a generalized Fibonacci sequence {$q_n$}. We give a generating matrix for {$q_n$}. With the aid of this matrix, we derive and re-prove some properties involving terms of this sequence.

• Communications for Statistical Applications and Methods
• /
• v.9 no.2
• /
• pp.543-553
• /
• 2002

Principal component analysis is applied to reduce p-dimensions into q-dimensions ( $q {\leq} p$). Any partition of a collection of data points with p and q variables generated by the application of six hierarchical clustering methods is re-classified by discriminant analysis. From the application of discriminant analysis through each hierarchical clustering method, correct classification ratios are obtained. The results illustrate which method is more reasonable in exploratory data analysis.