• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.10a
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• pp.51-54
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• 2005

Clustering analysis is a descriptive task that seeks to identify homogeneous groups of objects based on the values of their attributes. In this paper we propose a new algorithm for K-medoids clustering which runs like the K-means algorithm. The new algorithm calculates distance matrix once and uses it for finding new medoids at every iterative step. We evaluate the proposed method using real and synthetic data and compare with the results of other algorithms. The proposed algorithm takes reduced time in computation and better performance than others.

• Journal of the Korean Mathematical Society
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• v.60 no.1
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• pp.227-253
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• 2023

In this article, we generalize the results discussed in [6] by introducing a genus to generic fibers of Lefschetz fibrations. That is, we give families of relations in the mapping class groups of genus-1 surfaces with boundaries that represent rational homology disk smoothings of weighted homogeneous surface singularities whose resolution graphs are 3-legged with a bad central vertex.

• Korean journal of food and cookery science
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• v.6 no.4 s.13
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• pp.59-68
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• 1990

Juices prepared from carrots, apples, and mandarin oranges were fermented with Leuconostoc mesenteroides or along with Saccharomyces cerevisiae. The pH of the fermented juices was not found significantly different between the mixed and single-cultured groups. The juices containing 0.5% NaCl had lower pH than the groups without 0.5% NaCl. The final pH of the single-cultured gruops was the highest among the sample groups. However, reducing sugar content of the mixed-cultured groups was lower than that of the single-cultured groups. The viable cells of the mixed-cutured groups were remarkably increased until 3 days of storage, and after 6 days they were gradually decreased. The results of the sensory evaluation demonstrated acidic, salty and alcoholic flavors were significantly different among the groups. The single-cultured group without salt was significantly more acidic than the non-pasteurized control group. The mixed-cultured group with salt was significantly more alcoholic than the group without salt and control groups. The non-pasteurized control group was significantly more homogeneous than the mixed-cultured groups and single-cultured group with salt. Preference ranking test showed that flavor and overall acceptability of the fermented juices was significantly different among the groups. Flavor of the single-cultured group without salt was found significantly better than those of the groups with salt. With the respect of overall acceptability, the single-cultured group without salt was significantly more acceptable than the non-pasteurized control group and the mixed-cultured group with salt.

• Polymer(Korea)
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• v.39 no.2
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• pp.300-310
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• 2015

In this study, we modified silica nanoparticles with N-[3-(trimethoxysilyl)propyl]ethylenediamine (TPED) silane coupling agent, which has one primary and one secondary amino groups in a molecule, to introduce amino groups on the silica surface. After modification of silica, we used 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM) to introduce methacrylate groups by Michael addition reaction. We found about 30% of N-H groups on the TPED modified silica surface reacted with acrylate groups of AHM compared to about 85% of reaction between N-H groups of pure TPED with acrylate groups of pure AHM. This lower degree of Michael addition reaction for heterogeneous reaction between N-H groups on the solid TPED modified silica and liquid AHM compared to homogeneous reaction between pure liquid TPED and pure liquid AHM may be caused by lower mobility of grafted amino groups of TPED moiety and higher steric hindrance caused by solid silica particles.

• Korean Journal of Remote Sensing
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• v.25 no.1
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• pp.21-30
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• 2009

The purposes of this paper are to present a selection method of neighboring pixels whose local statistics are similar to the center pixel and combine the selection result with mean curvature diffusion filter to reduce noises in remote sensed imagery. The order of selection of neighboring pixels is critical, especially for finding a pixel belonging to the homogeneous region, since the statistics of the homogeneous region vary according to the selection order. An effective strategy for selecting neighboring pixels, which uses rank-order differences vector obtained by computing the intensity differences between the center pixel and neighboring pixels and arranging them in ascending order, is proposed in this paper. By using region growing method, we divide the elements of the rank-ordered differences vector into two groups, homogeneous rank-ordered differences vector and outlier rank-ordered differences vector. The mean curvature diffusion filter is combined with a line process, which chooses selectively diffusion coefficient of the neighboring pixels belonging into homogeneous rank-ordered differences vector. Experimental results using an aerial image and a TerraSAR-X satellite image showed that the proposed method reduced more efficiently noises than some conventional adaptive filters using all neighboring pixels in updating the center pixel.

• Journal of the Korean Ceramic Society
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• v.24 no.6
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• pp.561-571
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• 1987

In case of glass ceramics and powder preparation from the metalakoxide solutions, metalakoxide solutions with a various species of alkoxy groups have unique characteristics. Therefore, in this study, the mixing ability of homogeneous sol, gel morphology and physical properties of gels were investigated by the changes in terms of the different four alkoxy groups, CH3-, C2H5-, i-C3H7-n-C4H9-, along with the catalyst for the purpose of the observation about the homogenous transition range from sol to gel. As a result, when the fixed condition was mol ratio of H2O/Si(OR)4=2.0 and variables were batch composition and addition amount of catalyst, the characteristics of Tetra-normal-Butoxysilane and Tetra-iso-propoxysilane systems had very narrow sol-gel conversion region than Tetramethoxysilane and Tetraethoxysilane system. And silicon-alkoxide, systems having narrow sol-gel conversion region were enlarged by addition of catalyst. In viewpoint of the weight loss of gel produced by hydrolysis of silicon alkoxide systems with different four alkoxy groups, the amounts of weight loss of gel containing large molecular alkoxy groups were much more than those of small molecular alkoxy group.

• Journal of the East Asian Society of Dietary Life
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• v.26 no.4
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• pp.285-296
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• 2016

This study was conducted to obtain a better understanding of American green tea consumers for increasing Korean green tea sales in the US market. In doing so, this study investigated green tea choice attributes of US consumers and segmented them based upon their perceptions about important attributes of green tea. A factor-cluster segmentation approach was used for this study. An exploratory factor analysis identified five green tea choice motives: 'Sensory', 'Diet', 'Price', 'Health', and 'Brand'. Based upon these five choice attributes, cluster analyses classified all respondents into four homogeneous subgroups: 'Highly motivated', 'Taste/Price oriented', 'Health oriented', and 'Brand oriented'. Cross-tab tests proved that green tea consumption and purchasing patterns were significantly different among the four clusters. In particular, two cluster groups representing 'Highly motivated' and 'Health oriented' groups were found to offer the most utility for further American green tea market segmentation research. Findings show that American green tea consumers include a wide range of age groups and they usually buy green tea at grocery markets. Managerial implications for all cluster groups based upon their unique characteristics are provided. Korean green tea companies can apply these findings in order to develop more effective and efficient marketing strategies to attract American consumers to buy more Korean green tea.

• Journal of The Korean Association For Science Education
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• v.22 no.4
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• pp.717-724
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• 2002

In this study. the effects of grouping by students' agreeableness in cooperative learning strategy applied to middle school science classes on their achievement. confidence, satisfaction, attitude toward science class, and cohesion of group members were investigated. One hundred and fifty-eight students were assigned to control group, homogeneous group and heterogeneous group, and taught about separation of mixture for 7 class hours. The results revealed that there was no significant difference in the achievement test scores. However, significant interaction between the instruction and the level of agreeableness were found in the satisfaction and the cohesion of group members. Students of higher agreeableness level in the homogeneous group were more satisfied with science class and cohesive. Students' attitude toward science class in the homogeneous group was also significantly higher than those in the other groups.

• Journal of Korean Society of Transportation
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• v.31 no.4
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• pp.85-94
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• 2013

The Continuous Risk Profile (CRP) has been well known to be the most accurate and efficient among existing network screening methods. However, the classical CRP uses safety performance functions (SPFs) which require a huge investment to construct a database system. This study aims to suggest a new CRP method using average crash frequencies of homogeneous groups, instead of SPFs, as rescaling factors. Hierarchical clustering analysis is performed to classify freeway segments into homogeneous groups based on the data of AADT and number of lanes. Using the data from I-880 in California, the proposed method is compared to other several network screening methods. The results show that the proposed method decrease false positive rates while it does not produce any false negatives. The method developed in this study can be easily applied to screen freeway networks without any additional complex database systems, and contribute to the improvement of freeway safety management systems.

• Journal of East-West Nursing Research
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• v.10 no.1
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• pp.41-52
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• 2004

Purpose: The purpose of this research was to compare the effects of Danjeon Breathing exercise and walking exercise on blood lipids, physical symptoms and hemoglobin of middle-aged women to determine which of these two exercises was more beneficial. Methods: The Danjeon breathing exercise group(20) took health management counseling and performed an eighty-minute Danjeon breathing exercise three times a week for 12 weeks while the walking exercise group(25) took health management counseling and performed a walking exercise seven hours per week for 12 weeks. The control group(20) received only health management counseling. The groups were homogeneous on age, religion, marital status, education, profession, monthly income per household, menopause, smoking, drinking, fat intake and cholesterol intake. Likewise, the groups were homogeneous on total cholesterol, HDL-cholesterol,atherogenic index, hemoglobin and physical symptoms. The collected data were analyzed by using the SPSS PC program and $x^2$-test, ANOVA, repeated measures of ANOVA and LSD. Results: 1. Total cholesterol of the Danjeon breathing exercise group and the walking exercise group were lower than that of the control group. 2. HDL- cholesterol of the Danjeon breathing exercise group and the walking exercise group were not higher than that of the control group. 3. Atherogenic index of the Danjeon breathing exercise group was lower than that of the control group, but atherogenic index of the walking exercise group was not lower than that of the control group. 4. Hemoglobin of the Danjeon breathing exercise group and the walking exercise group were not higher than that of the control group. 5. Physical symptom score of the Danjeon breathing exercise group was lower than those of the walking exercise group and the control group, but Physical symptom score of the walking exercise group was not lower than that of the control group. Conclusion: Danjeon breathing exercise and walking exercise are effective for decreasing total cholesterol of middle-aged women. Danjeon breathing exercise is more effective for decreasing atherogenic index and physical symptoms of middle-aged women than walking exercise.