• Environmental Engineering Research
• /
• v.15 no.3
• /
• pp.135-140
• /
• 2010

With the various urban characteristics of each city, the existing water demand prediction, which uses average liter per capita day, cannot be used to achieve an accurate prediction as it fails to consider several variables. Thus, this study considered social and industrial factors of 164 local cities, in addition to population and other directly influential factors, and used main substance and cluster analyses to develop a more efficient water demand prediction model that considers unique localities of each city. After clustering, a multiple regression model was developed that proved that the $R^2$ value of the inclusive multiple regression model was 0.59; whereas, those of Clusters A and B were 0.62 and 0.74, respectively. Thus, the multiple regression model was considered more reasonable and valid than the inclusive multiple regression model. In summary, the water demand prediction model using principal component and cluster analyses as the standards to classify localities has a better modification coefficient than that of the inclusive multiple regression model, which does not consider localities.

• Journal of Communications and Networks
• /
• v.12 no.4
• /
• pp.358-365
• /
• 2010

We develop a low complexity cooperative diversity protocol for low energy adaptive clustering hierarchy (LEACH) based wireless sensor networks. A cross layer approach is used to obtain spatial diversity in the physical layer. In this paper, a simple modification in clustering algorithm of the LEACH protocol is proposed to exploit virtual multiple-input multiple-output (MIMO) based user cooperation. In lieu of selecting a single cluster-head at network layer, we proposed M cluster-heads in each cluster to obtain a diversity order of M in long distance communication. Due to the broadcast nature of wireless transmission, cluster-heads are able to receive data from sensor nodes at the same time. This fact ensures the synchronization required to implement a virtual MIMO based space time block code (STBC) in cluster-head to sink node transmission. An analytical method to evaluate the energy consumption based on BER curve is presented. Analysis and simulation results show that proposed cooperative LEACH protocol can save a huge amount of energy over LEACH protocol with same data rate, bit error rate, delay and bandwidth requirements. Moreover, this proposal can achieve higher order diversity with improved spectral efficiency compared to other virtual MIMO based protocols.

• Communications for Statistical Applications and Methods
• /
• v.12 no.3
• /
• pp.683-696
• /
• 2005

The results of using principal coordinates prior to cluster analysis are investigated on the samples from multiple binary outcomes. The retrieval ability of the known clustering algorithm is significantly improved by using principal coordinates instead of using the distance directly transformed from four association coefficients for multiple binary variables.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.1
• /
• pp.168-186
• /
• 2016

In this paper, we investigate the degrees of freedom (DoF) of a two-cluster multiple-input multiple-output (MIMO) multiway relay interference channel (mRIC), where there are two relays and two users per cluster. In this channel, users within the same cluster exchange messages among themselves with the help of two relays.We first obtain the DoF upper bound of the considered MIMO mRIC based on cut-set bound. Then, we propose a novel transmission strategy, blind interference neutralization (BIN), to approach the DoF upper bound. This new method utilizes the overheard information at two relays and focuses on the beamforming matrix designs at two relays so that the channel state information (CSI) at users is not required. Through theoretical analysis and numerical simulations, we show that the DoF upper bound can be obtained by using the BIN scheme. From simulation results, we show that the proposed BIN scheme can provide significant performance gain over the conventional time division multiple access (TDMA) scheme in terms of DoF. In addition, we show that the BIN scheme is a superior approach to the existing signal space alignment (SSA) schemes for the considered mRIC.

• Journal of Korean Society for Atmospheric Environment
• /
• v.9 no.4
• /
• pp.278-287
• /
• 1993

In order to calssify smog type durnig the summer season in Seoul, air Quality and meterorological data were analyzed by multivariate analysis. Among 15 variables relating to visibility, 10 variables were selected by multiple regression analysis for clustering of smog types; total suspended particle, sulfur dioxide, ozone, ntrogen dioxide, total hydrocarbon, south-north wind component, ralative humidity, precipitable water, mixing height and air temperature. Somg types were grouped into three clusters using cubic clustering criterion and the mumbers of days in each cluster were contained 74, 28 and 16 days. Each cluster was seperated clearly by sulfur dioxide, precipitable water and air teperature. The first cluster was representative of high ozone concentration and prevailing meterological conditions for ozone formation. Therefore, visibility in the first cluster was considered to be affected by photochemical smog. The third cluster showed characteristics of sulphurous smog type due to the higher concentration of primary pollutant, based on the dry condition than that in another cluster. On the other hand, the characteristic of the second cluster was not relatively clear, but considered to be in an intermediate characteristic between photochemical smog and sulphurous smog type.

• Journal of Korean Society for Atmospheric Environment
• /
• v.32 no.5
• /
• pp.513-525
• /
• 2016

To propose an effective ensemble methods in predicting $PM_{10}$ concentration, six experiments were designed by different ensemble average methods (e.g., non-weighted, single weighted, and cluster weighted methods). The single weighted method was calculated the weighted value using both multiple regression analysis and singular value decomposition and the cluster weighted method was estimated the weighted value based on temperature, relative humidity, and wind component using multiple regression analysis. The effects of ensemble average methods were significantly better in weighted average than non-weight. The results of ensemble experiments using weighted average methods were distinguished according to methods calculating the weighted value. The single weighted average method using multiple regression analysis showed the highest accuracy for hourly $PM_{10}$ concentration, and the cluster weighted average method based on relative humidity showed the highest accuracy for daily mean $PM_{10}$ concentration. However, the result of ensemble spread analysis showed better reliability in the single weighted average method than the cluster weighted average method based on relative humidity. Thus, the single weighted average method was the most effective method in this study case.

• Korean Journal of Child Studies
• /
• v.35 no.2
• /
• pp.103-115
• /
• 2014

This study explored the creative thinking styles of children according to cluster analysis and examined group differences in the gender of children. The participants consisted of 250 elementary school students living in Seoul, Korea. Data were analyzed by means of cluster analysis and ${\chi}^2$ test. The results from the cluster analysis based on the scores on the sub-factors of TTCT(Torrance Test of Creative Thinking) suggested the existence of four clusters('Non-creative', 'Divergent creative', 'Elaborate creative, 'Multiple creative'). Additionally, four clusters were found to be differentiated according to gender.

• Journal of the Korean Home Economics Association
• /
• v.40 no.8
• /
• pp.123-135
• /
• 2002

The purpose of this study is to examine the relationship between shopping orientation and purchasing satisfaction of apparels. To achieve the purpose, this study was carried out by means of questionnaires with female consumers aged from 20s to 50s in Daegu. The data were analysed by the frequency analysis, percentage, reliability test, factor analysis, Pearson's correlation analysis, cluster analysis, one-way ANOVA and Duncan's multiple range analysis. The statistical package for social science 9.0 for Window was used for the statistical processing of the data. The result of this study is summarized as follows. 1. To examine factors which construct female consumers' shopping orientation for apparels, a factor analysis was done, therefore, which obtained 6 factors. Also A factor analysis was done to examine the motivative factors of satisfaction with purchased apparels, 6 factors were obtained. 2. Based on the average score of shopping-orientation factors for apparels, a cluster analysis was done and it was classified into 3 clusters. There were differences in purchasing satisfaction of purchased apparels between the 3 clusters. 3. The differences in variety, shopping convenience, dignity, brand & preference, and convenient selection between the clusters were entirely p<0.001 which were very significant. There were no differences in the quality and service factors between the brand-/practicality-oriented cluster and entertainment-oriented cluster. With other factors, entertainment-oriented cluster was most satisfied than brand-/ practicality oriented cluster. But, self-reliance-oriented cluster was lowest purchasing satisfaction of apparels.

• Preventive Nutrition and Food Science
• /
• v.7 no.2
• /
• pp.201-206
• /
• 2002

Findings from European and American studies have indicated such health behaviors as smoking, drinking, lack of exercise, and insufficient intake of grains, fruits and vegetables as risk factors for hypertension. However, because dietary pattern and health behaviors of Korean differ from people of other countries, the risk factors for Koreans could be different. Therefore, the aim of this study was to identify food consumption patterns and health behavior characteristics of Korean hypertensive adults. Data on food consumptions and other health behaviors such as smoking, drinking, and exercise together with development of hypertension were collected from 597 persons aged 20 to 69 years in a local community. The first stage of analysis utilized cluster analysis to aggregate individuals into different health behavior and food consumption groups. Four health behavior groups were characterized by passive cluster, smoker cluster, fitness cluster and drinker cluster. Food consumption patterns of the subjects were also aggregated into 4 different clusters: dairy cluster, grain & vegetable cluster, fruit cluster, and fish & meat cluster. Then univariate analysis was followed to identify the variables associated with hypertension. The final stage of analysis was the identification of the relative importance of the variables selected from the univariate analysis on hypertension, using multiple logistic analysis. The results showed that heavy drinking was the most significant health behavior associated hypertension, which was similar to the findings in European and American studies. However, unlike the findings from foreign studies, grain and vegetable consumption appeared to be a risk factor for hypertension. A possible reason for the contradictory results between Korean and Western studies may be the dependence of Koreans on white rice as the major staple food, and/or the frequent consumption of salted vegetables, rather than fresh vegetables as is customary in Europe and America.

• Culinary science and hospitality research
• /
• v.17 no.2
• /
• pp.74-84
• /
• 2011

The purpose of this study is to understand the relationship between educational environment services offered and student satisfaction with them. A survey was conducted to 314 students in a cooking and food service program. To achieve the purpose of this study, SPSS 17.0, a statistics program, was used for a descriptive analysis, a frequency analysis, a factor analysis, a multiple regression analysis, a cluster analysis and a One-Way ANOVA analysis. The hypothesis test result of the effect of educational environment services on satisfaction showed that there was a partially significant effect in satisfaction with facilities and lecturers(p<0.01) as well as administrative services (p<0.01). In the cluster analysis of educational environment services, cluster 1 was classified as a mistry cluster, cluster 2 as a satisfied cluster, cluster 3 as a dissatisfied cluster and cluster 4 as a positive cluster. They showed a statistically meaningful result in the one-way ANOV A(p<0.01).