• KIPS Transactions on Software and Data Engineering
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• v.3 no.11
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• pp.479-486
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• 2014

MapReduce is a programing model used for parallelly processing a large amount of data. To analyze a large amount data, the data cube is widely used, which is an operator that computes group-bys for all possible combinations of given dimension attributes. When the number of dimension attributes is n, the data cube computes $2^n$ group-bys. In this paper, we propose an efficient method for computing data cubes using MapReduce. The proposed method partitions $2^n$ group-bys into $_nC_{{\lceil}n/2{\rceil}}$ batches, and computes those batches in stages using ${\lceil}n/2{\rceil}$ MapReduce jobs. Compared to the existing methods, the proposed method significantly reduces the amount of intermediate data generated by mappers, so that the cost of sorting and transferring those intermediate data is reduced significantly. Consequently, the total processing time for computing a data cube is reduced. Through experiments, we show the efficiency of the proposed method over the existing methods.

• Proceedings of the Korea Database Society Conference
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• 1999.06a
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• pp.95-102
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• 1999

The web-based group collaborative systems are emerging as enterprise-wide information systems. Since data in group collaborative systems are apt to be shared among multiple concurrent users and modified simutaneously by them, the web-based group collaborative systems must support synchronous collaboration in order to provide users with synchronized and consistent views of shared data. This Paper proposes an active web server which can facilitate synchronous collaboration in web-based group collaborative systems. To accomplish such a goal, the active web server manages dependency relationships between shared data and web browsers referencing them and actively propagates changing details of the shared data to all web browsers referencing them. And, this paper examines usefullness and effectiveness of the active web server to apply it to the ball-bearing design example of concurrent engineering design systems. The prototype system of the active web server is developed on a commercial Object-oriented Database Management System (ODBMS) called OBJECTSTORE using the C＋＋ programming language.

• Journal of the Society of Disaster Information
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• v.5 no.1
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• pp.122-139
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• 2009

USN Middleware plays roles of broker between sensors and applications. It collects sensor data, decides the situation and sends the result to the applications. It is not good to decide the situation from one sensor data, because it may error data or reflect small part of all. In this paper, we propose the disaster management model based on the concept 'group' and 'semantic information' from the sensing data. Group is the primary unit to decide the situation. It consists of several sensors which were installed in the same place and had the same pre-defined condition to act. For example, all fire sensors in the room simultaneously trigger the ring when the same pre-defined temperature is recorded. Then, the all fire sensors are included to the same one sensor group. All operations of the intelligent USN middleware are based on the 'group' unit. Disaster information is the result of the interpretation of the sensing data. based on the 'group', the disaster meaning is processed.

• Korean Management Science Review
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• v.19 no.1
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• pp.189-196
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• 2002

Data clustering is often one of the first steps in data mining analysis. It Identifies groups of related objects that can be used as a starling point for exploring further relationships. This technique supports the development of population segmentation models, such as demographic-based customer segmentation. This paper Purpose to present the development of two phase hierarchical clustering algorithm for group formation. Applications of the algorithm for product-customer group formation in customer relationahip management are also discussed. As a result of computer simulations, suggested algorithm outperforms single link method and k-means clustering.

• PNF and Movement
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• v.20 no.1
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• pp.19-29
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• 2022

Purpose: The purpose of this study was to analyze the gait patterns of adults with intellectual disability and healthy adults based on collected kinematic data on the lower extremities and to investigate the gait patterns of intellectually disabled people by comparing the differences between the two groups. Methods: The participants were divided into in one group of healthy adults (n = 9) and one group with mild intellectual disabilities (n = 9). 3D motion analysis (Myomotion) was used to collect kinematic data from each group while the participants walked 3 times over 10 m. As a statistical method, each group's kinematic data during walking was analyzed and compared using an independent sample t-test. Results: Comparing the kinematic data of the lower extremities during walking between the group with mild intellectual disability and the healthy group, there were significant differences between the two groups in the hip and ankle joints in the stance and swing phases. Conclusion: The analysis suggests that people with intellectual disabilities have kinematic differences compared with healthy people. Based on the results of this study, it is necessary to conduct further research on rehabilitation programs for joint stabilization, exercise for increasing joint range of motion, muscle strengthening exercise, and proprioception training for people with intellectual disabilities with insufficient physical function.

• The Journal of Korean Medicine
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• v.45 no.1
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• pp.127-138
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• 2024

Objectives: Cold extremities have been suggested to correlate with sleep disturbances. This study aims to explore the relationship between thermal sensations in body, encompassing both cold and heat sensations, with sleep quality and insomnia. Methods: Self-administered questionnaires were utilized to assess thermal sensations in body, sleep quality and symptoms of insomnia in middle-aged women. A multiple logistic regression analysis was performed to ascertain the association between thermal sensations in body and both sleep quality and insomnia symptoms. Results: Among 899 participants, 255 (28.4%) were categorized in the cold sensation group, 95 (10.6%) in the heat sensation group, 70 (7.8%) in the group with both cold and heat sensations, and 479 (53.3%) in the no-sensation group. Pittsburgh Sleep Quality Index and Insomnia Severity Index were notably higher in the group experiencing both sensations when compared to the no-sensation group. After adjustments for covariates, the odds ratios for poor sleep quality, moderate/severe insomnia, and long sleep latency were significantly elevated in the group with both sensations when compared to the no-sensation group. The odds ratios for poor sleep quality in the cold sensation group and for moderate/severe insomnia and low sleep efficiency in the heat sensation group were significantly higher when compared to the no-sensation group. Conclusions: The risk for sleep disturbances varied depending on the presence of thermal sensations in body, with the greatest risk observed for low sleep quality and insomnia in individuals experiencing both cold and heat sensations.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.113-116
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• 2000

The effect due to group delay and non linear characteristics in high speed data satellite channel was represented in this paper. Based on the modeling of group delay and non linear characteristics the performance was analyzed in ka band satellite channel. The group delay and non-linear characteristics in high speed data transmission severely affect the system performance. The more Eb/No is required to satisfy the required system performance. The optimum operating points of HDR satellite transmission system are implemented by considering analyzed results for channel characteristics

• KIISE Transactions on Computing Practices
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• v.21 no.5
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• pp.387-392
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• 2015

MapReduce is a framework used to process large data sets in parallel on a large cluster. A group-by query is a query that partitions the input data into groups based on the values of the specified attributes, and then evaluates the value of the specified aggregate function for each group. In this paper, we propose an efficient method for processing multiple group-by queries using MapReduce. Instead of computing each group-by query independently, the proposed method computes multiple group-by queries in stages with one or more MapReduce jobs in order to reduce the total execution cost. We compared the performance of this method with the performance of a less sophisticated method that computes each group-by query independently. This comparison showed that the proposed method offers better performance in terms of execution time.

• Health Policy and Management
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• v.33 no.2
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• pp.118-128
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• 2023

Background: Personal socio-economic abilities are crucial as it affects health inequalities. These multidimensional inequalities across the regions have been structured and fixed. This study aimed to analyze health vulnerabilities by regional cluster and identify regional health disparities of self-rated health, using nationally representative cross-sectional data. Methods: This study used personal and regional data. Data from the Community Health Survey 2021 were analyzed. K-means cluster analysis was applied to 250 si-gun-gu using administrative regional data. The clusters were based on three areas: physical environment, health-related behaviors and biological factors, and the psychosocial environment through the conceptual framework for action on the social determinants of health. And binary logistic regression analyses were conducted to examine the differences in self-rated health status by the regional clusters, controlling human biology, environment, lifestyle, and healthcare organization factors. Results: The most vulnerable group was group 3, the moderate vulnerable group was group 1, and the least vulnerable group was group 2. The group 2 was more likely to have high self-rated health status than the moderate vulnerable group (odds ratio [OR], 1.023; p<0.001). And the group 3 showed low self-rated health status than the moderate vulnerable group (OR, 0.775; p<0.001). However, the moderate vulnerable group had significantly higher self-rated health status than the most vulnerable group (group 2: OR, 1.023; p<0.001; group 3: OR, 0.775; p<0.001). Conclusion: These results demonstrate that community members' health status is influenced by regional determinants of health and individual levels. And these contribute to understanding the importance of specific and differentiated interventions like locally tailored support programs considering both individual and regional health determinants.

• Journal of Internet Computing and Services
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• v.3 no.5
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• pp.87-94
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• 2002

This paper proposes a group key management protocol for a secure of all the multcast user in PIM-SM multicast group communication. Each subgroup manager gives a secure key to it's own transmitter and the transmitter compress the data with it's own secure key from the subgroup manager, Before the transmitter send the data to receiver, the transmitter prepares to encrypt a user's service by sending a encryption key to the receiver though the secure channel. after checking the user's validity through the secure channel, As the transmitter sending a data after then, the architecture is designed that the receiver will decode the received data with the transmitter's group key, Therefore, transmission time is shortened because there is no need to data translation by the group key on data sending and the data transmition is possible without new key distribution at path change to shortest path of the router characteristic.