• Journal of Korean Society for Atmospheric Environment
• /
• v.13 no.1
• /
• pp.51-63
• /
• 1997

Total suspended particulate matters in the ambient air were analyzed for eight chemical elements (Ca, Co, Cu, Fe, Mn, Pb, Si, and Zn) using an x-ray fluorescence spectrometry (XRF) at the Kyung Hee University - Suwon Campus during 1989 to 1994. To use these data as basis for source identification study, membership of each sample was selected to represent one of the well defined sample groups. The data sets consisting of 83 objects and 8 variables were initially separated into two groups, fine (d$_{p}$<3.3 ${\mu}{\textrm}{m}$) and coarse particle groups (d$_{p}$>3.3 ${\mu}{\textrm}{m}$). A hierarchical clustering method was examined to obtain possible member of homogeneous sample classes for each of the two groups by transforming raw data and by applying various distances. A disjoint principal component analysis was then used to define homogeneous sample classes after deleting outliers. Each of five homogeneous sample classes was determined for the fine and the coarse particle group, respectively. The data were properly classified via an application of logarithmic transformation and Euclidean distance concept. After determining homogeneous classes, correlation coefficients among eight chemical variables within all the homogeneous classes for calculated and meteorological variables (temperature. relative humidity, wind speed, wind direction, and precipitation) were examined as well to intensively interpret environmental factors influencing the characteristics of each class for each group. According to our analysis, we found that each class had its own distinct seasonal pattern that was affected most sensitively by wind direction.ion.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.3
• /
• pp.471-480
• /
• 2023

The purpose of this study is to confirm the effect of recording online classes and real-time video classes on other behaviors, lecture satisfaction, and lecture flow in during the COVID-19 period. Data were collected and analysis using a structured questionnaire from May 20th to June 4th in 2021 for 550 nursing students in the D University. As a result of the study, it was found that there were more others behaviors in record online classes than in real-time online classes (t=-2.00, p=.046), lecture satisfaction(t=-1.54, p=.124) and lecture flow in real-time online classes it was higher in the record online classes (t=-.63, p=.529), but it was not statistically significant. However, the 2nd year students who participated in the two types of online classes showed statistically significantly higher lecture satisfaction (t=13.55, p=.000) and lecture flow(t=4.48, p=.004). And 4 th grade students of others behaviors was statistically significantly lower (t=4.68, p=.003). In the multiple regression analysis, the main factor affecting lecture flow was lecture satisfaction, and the explanatory power of the model was 55.1% in record online classes (F=128.49, p <.01), and in real-time classes 47.2%(F=77.24, p<.01). In the future, research should be conducted to confirm the difference between the two types of online classes of the same instructor and the difference in other things, lecture satisfaction, and class commitment that appear after applying learner-centered learning.

• Journal of the Korean earth science society
• /
• v.42 no.4
• /
• pp.459-469
• /
• 2021

In this study, we investigated the difference in the affective characteristics between science-gifted students and general students through the positive experiences about science (PES) index. We also explored ways to apply the characteristics of gifted classes suggeseted by the teachers of this study, which had a positive effect on science-gifted students, to general science classes. For this study, a PES survey was carried on middle school science-gifted students enrolled in the gifted education center in the central region and general middle school students in the same area who had no experience in gifted education. Based on the survey result, we conducted in-depth interviews with teachers, having teaching experience with both science-gifted and general students. The results revealed that science-gifted students showed a significantly higher PES index than general students in all five areas of PES. The area with the largest difference between the two groups was science-related self-concept and the smallest was science academic emotion. Teachers suggested ways to apply the characteristics of science-gifted classes to general science classes, such as organizing general science classes around inquiry activities, supporting class materials such as MBL or tablets, reconstructing the classes using materials reflecting students' needs, and changing the textbook content and narrative style, to induce students' interest and curiosity. Based on the study results, ways to enhance the PES through science classes for general students were proposed.

• Journal of Science Education
• /
• v.45 no.2
• /
• pp.257-273
• /
• 2021

This study explores classes for pre-service mathematics teachers. The purpose of this study is to examine the differences between 'non-face-to-face' classes & 'face-to-face' classes, as well as the differences in learning outcomes between these two methods. A Professors' Learning Group was formed to effectively carry out this study. Through this learning group, we shared how to plan and operate the lecture. The subjects of this study are 'non-face-to-face calculus courses & face-to-face calculus courses' and 'non-face mathematics education theory courses & face-to-face mathematics education theory courses." Specifically, in these two pairs of courses, we analyze the differences in course management and the differences in the outcomes of students' assessments. Non-face-to-face classes were planned, developed, implemented and evaluated based on the 'non-face class design model.' The results of this study are as follows: First, we explored the differences between 'non-face-to-face classes/mixed classes' and 'face-to-face classes.' Second, the achievement results in calculus courses were higher in face-to-face classes than in non-face classes. Third, the results of achievements in mathematics education theory courses were higher in mixed classes than in face-to-face classes. Through the results of this study, we hope that the non-face-to-face class capabilities can be improved in pre-service mathematics teacher training.

• Proceedings of the Korean Association for Survey Research Conference
• /
• 2002.11a
• /
• pp.255-274
• /
• 2002

We classify rotation sampling designs into two classes. The first class replaces sample units within the same rotation group while the second class replaces sample units between different rotation groups. The first class is specified by the three-way balanced design which is a multi-level version of previous balanced designs. We introduce an extended generalized composite estimator (EGCE) and derive its variance and mean squared error for each of the two classes of design, cooperating two types of correlations and three types of biases. Unbiased estimators are derived for difference between interview time biases, between recall time biases, and between rotation group biases. Using the variance and mean squared error, since any rotation design belongs to one of the two classes and the EGCE is a most general estimator for rotation design, we evaluate the efficiency of EGCE to simple weighted estimator and the effects of levels, design gaps, and rotation patterns on variance and mean squared error.

• English Language & Literature Teaching
• /
• v.15 no.4
• /
• pp.177-197
• /
• 2009

This study investigated the effects of dictation practice, in terms of listening proficiency and the use of listening strategy. The research was implemented for 15 weeks with 89 freshmen and sophomores at a Korean university. The subjects were divided into an experimental group and a control group. All conditions were the same in both groups, except that the experimental group had dictation practice on a regular basis in their listening classes through one semester. For the purpose of the study, two research questions were set; 1) Does dictation practice improve listening proficiency? 2) What are the differences in the use of listening strategies between the two groups? Does dictation practice make the participants use different listening strategies? A sample TOEIC listening test was conducted as a pre-test and post-test. A questionnaire was used to find out the differences in the use of listening strategies between the two groups. The results of this study reveal that there was no statistically difference in improvement between the two groups; however, the experimental group scored much higher on the post-test than the pre-test compared with the control group. In regard to listening strategies, among 6 listening strategies, the use of metacognitive listening strategies had a significant difference between the two groups. On the basis of the results, the study suggested some guidelines for dictation practice in EFL listening classes and called for more studies on its effects.

• Journal of the Korean Mathematical Society
• /
• v.36 no.6
• /
• pp.1075-1090
• /
• 1999

This paper deals with Littlewood-Paley type estimates of the Besov spaces {{{{ { B}`_{p,q } ^{$\alpha$ } }}}} on the d-dimensional unit cube for 0< p,q<$\infty$ by two certain classes. These classes are including biorthogonal wavelet systems or dual multiscale systems but not necessarily obtained as the dilates or translates of certain fixed functions. The main assumptions are local supports of both classes, sufficient smoothness for one class, and sufficiently many vanishing moments for the other class. With these estimates, we characterize the Besov spaces by coefficient norms of decompositions with respect to biorthogonal wavelet systems on the cube.

• Korean Journal of Remote Sensing
• /
• v.20 no.5
• /
• pp.353-359
• /
• 2004

This study proposes an approach to unsupervisedly estimate the number of classes and the parameters of defining the classes in order to train the classifier. In the proposed method, the image is segmented using a spatial region growing based on hierarchical clustering, and fuzzy training is then employed to find the sample classes that well represent the ground truth. For cluster validation, this approach iteratively estimates the class-parameters in the fuzzy training for the sample classes and continuously computes the log-likelihood ratio of two consecutive class-numbers. The maximum ratio rule is applied to determine the optimal number of classes. The experimental results show that the new scheme proposed in this study could be used to select the regions with different characteristics existed on the scene of observed image as an alternative of field survey that is so expensive.

• The KIPS Transactions:PartB
• /
• v.12B no.3 s.99
• /
• pp.337-342
• /
• 2005

This paper presents a typographical analyses and classes. Typographical analysis is an indispensable tool for machine-printed character recognition in English. This analysis is a preliminary step for character segmentation in OCR(Optical Character Recognition). This paper is divided into two parts. In the first part, word typographical classes from words are defined by the word typographical analysis. In the second part, character typographical classes from connected components are defined by the character typographical analysis. The character typographical classes are used in the character segmentation.

• Journal of Korean Elementary Science Education
• /
• v.23 no.1
• /
• pp.37-43
• /
• 2004

In this study, we investigated the effects of using concept mapping as an instructional tool on 4th graders' achievement, science learning motivation, and attitude toward science classes. Two classes (38 students) from an elementary school were respectively assigned to a control group and a treatment group. Students were taught about "expansion of matter by heat" and "heat transfer". These topics were chosen because they require students to understand more concepts as well as relationships among them. A science learning motivation test and an attitude toward science classes test were administered as pretests. A researcher-made achievement test, the science learning motivation test, and the attitude toward science classes test were administered as posttests. The results indicated that using concept mapping in 4th-grade science classes was not significantly effective in improving students' achievement though a statistically significant positive effect was found in the subcategory of knowledge. No statistically significant effect of using concept mapping was found in the scores of the science learning motivation test and the attitude toward science classes test. Educational implications are discussed.