• The KIPS Transactions:PartC
• /
• v.11C no.7 s.96
• /
• pp.895-904
• /
• 2004

Due to the frequent and unpredictable topology changes, multicast still remains as challenge and no one-size-fits-all protocol could serve all kinds of needs in mobile ad hoc network. In this paper, we propose a novel scheme of Hierarchical Eulerian Ring Oriented Multicast Architecture (HEROMA) over mobile ad hoc network. It has features that concentrate on efficiency and robustness simultaneously. It is also an application-driven proposal for hazard detection. Architectures including Eulerian ring, hierarchy and multicast agent are investigated in detail Simulation results different level of improvements on control traffic, end-to-end delay and packet delivery ratio by comparing with tree-based and mesh-based multicast protocols.

• International Journal of CAD/CAM
• /
• v.7 no.1
• /
• pp.1-10
• /
• 2007

The compression of CAD models is a key technology for realizing Internet-based collaborative product development because big model sizes often prohibit us to achieve a rapid product information transmission. Although there exist some algorithms for compressing discrete CAD models, original precise CAD models are focused on in this paper. Here, the characteristics of hierarchical structures in CAD models and the distribution of their redundant data are exploited for developing a novel data encoding method. In the method, different encoding rules are applied to different types of data. Geometric data is a major concern for reducing model sizes. For geometric data, the control points of B-spline curves and surfaces are compressed with the second-order predictions in a local coordinate system. Based on analysis to the distortion induced by quantization, an efficient method for computation of the distortion is provided. The results indicate that the data size of CAD models can be decreased efficiently after compressed with the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.9A
• /
• pp.874-881
• /
• 2010

Acoustic signal, which is a main carrier of underwater communication, attenuates along the traveled path heavily depending on the frequency as well as inter-node distance. In addition, since it has a long propagation delay, the conventional medium access control (MAC) schemes requiring complex signaling procedures and accordingly heavy overhead messages would not be appropriate in underwater communications. In this paper, we propose a code division multiple access (CDMA) scheme as a solution for MAC of underwater communication and evaluate the performance. A hierarchical data-gathering tree topology is considered and a staggered wake-up pattern is employed for the purpose of energy saving. As a performance measure, the data rate at each level of hierarchical topology is derived.

• Korea Journal of Hospital Management
• /
• v.26 no.1
• /
• pp.26-41
• /
• 2021

Purpose: This study is to identify the relationship among married nurses' social support, work-family conflict and work-family enrichment and to examine the influence of social support on work-family conflict and work-family enrichment. Methods: Data were collected from married nurses working at three hospitals with more than 100 beds in J Province and analyzed by descriptive statistics, t-test, ANOVA, Mann-Whitney U test, Kruskal-Wallis H test, Pearson's correlation analysis and hierarchical regression analysis using SPSS 21 program. Findings: In the correlation analysis only social support and work-family enrichment showed positive correlation. As a result of hierarchical multiple regression analysis, social support still acted as a significant influence factor on work-family conflict and work-family enrichment even in the state of considering the effect of control variables. Conclusion: In order to lower work-family conflict and to enhance work-family enrichment of married nurses, it is necessary to introduce and implement welfare policies for work-family reconciliation at the workplace level and at home level it is necessary to provide concrete measures so that married nurses can find the value of life as workers while house working and nurturing.

• Journal of Korea Multimedia Society
• /
• v.25 no.8
• /
• pp.983-990
• /
• 2022

In this paper, we implemented a hierarchical encryption system using two-step phase-shifting digital holography(PSDH) technology based on XOR and scramble operations. The proposed encryption system is a system that authenticates access through the issuance of an encryption key for access to individual laboratories, department offices, and universities. In the encryption process, we proposed a double encryption method using XOR and scramble operation with digital technology and two-step phase-shifting digital holography with optical technology. In the two-step PSDH process, an new method of determining the reference wave intensity without measuring it by using random common object image gererated from digital encryption process was also proposed. In the decryption process, the process is performed in the reverse order of encryption process. And only when the various key information used in the encryption process is correct, the encrypted information can be decrypted, so that the user can access the desired place. That is, there is a feature that can hierarchically control the space that can be accessed according to the type of key issued in the proposed encryption system. Through the computer simulation, the feasibility of the proposed hierarchical encryption system was confirmed.

• The Journal of Information Technology and Database
• /
• v.1 no.1
• /
• pp.31-62
• /
• 1994

Information systems for application areas like office automation, customer service or computer aided manufacturing are usually highly interactive and deal with complex document structures composed of multiple media formats. For the realization of these systems, nonstandard database systems, which we call document databases, need to handle different types of coarse-and fine-grained document objects(like full-text documents, graphics and images), hierarchical and non-hierarchical relationships between objects(like composition-links and cross-references using hypertext structures) and document attributes of different types such as formatting/presentation information and access control. In this paper, we present the underlying data model for document databases based on descriptive markup languages that provide mechanisms for specifying the logical structure(or schema) of individual documents stored in the database. We then describe extensions to the data model for supporting notion of composite structures("join" operators for documents) --composition and hyperlinking mechanisms for representing compound documents and inter-linked documents as unique entites separate from their components. Furthermore, due to the interactive nature of the application domains, the database system in conjunction with clients(or browsers) has to support visual navigation and graphical query mechanisms. We describe the functionality of a new user interface paradigm called HyBrow for meeting the above mentioned requirements. The underlying implementation strategy is also discussed.discussed.

• Child Health Nursing Research
• /
• v.26 no.3
• /
• pp.357-365
• /
• 2020

Purpose: The aim of this study was to investigate internet addiction among middle school students and to examine the mediating effects of social support in the relationships of self-efficacy and self-control with internet addiction. Methods: The participants in the study were 119 middle school students in J city. The measurements included a self-efficacy scale, a self-control scale, a social support scale, and the Internet Addiction Scale for Youth. Data were analyzed using the independent t-test or Mann-Whitney U test, one-way analysis of variance, the Scheffé test, Pearson correlation coefficients, and multiple-regression using SPSS version 22.0. Mediation effects were analyzed by the Sobel test and Baron and Kenny's hierarchical analysis technique. Results: Significant correlations were found among self-efficacy, self-control, and internet addiction. Social support had partial mediating effects in the relationship between self-efficacy and internet addiction, as well as in the relationship between self-control and internet addition. Conclusion: In order to prevent internet addiction, the promotion of interactions among peers, which is a component of social support, is particularly important. It is also necessary to promote face-to-face activities that can strengthen relationships. The findings suggest that intensifying social support may help reduce the level of internet addiction in middle school students.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.610-615
• /
• 2005

Visual servoing is the fusion of results from many elemental areas including high-speed image processing, kinematics, dynamics, control theory, and real-time computing. It has much in common with research into active vision and structure from motion, but is quite different from the often described use of vision in hierarchical task-level robot control systems. We present a new approach to visual feedback control using image-based visual servoing with the stereo vision in this paper. In order to control the position and orientation of a robot with respect to an object, a new technique is proposed using a binocular stereo vision. The stereo vision enables us to calculate an exact image Jacobian not only at around a desired location but also at the other locations. The suggested technique can guide a robot manipulator to the desired location without giving such priori knowledge as the relative distance to the desired location or the model of an object even if the initial positioning error is large. This paper describes a model of stereo vision and how to generate feedback commands. The performance of the proposed visual servoing system is illustrated by the simulation and experimental results and compared with the case of conventional method for dual-arm robot made in Samsung Electronics Co., Ltd.

• Child Health Nursing Research
• /
• v.22 no.2
• /
• pp.97-106
• /
• 2016

Purpose: The purpose of this study was to identify the relationship between mother child-rearing attitude, language control styles and preschool child's social competence, and also, to provide a basis for development of a program to promote preschool child's social competence. Methods: The present study was a descriptive research. Participants in this study were a convenience sample of 300 preschool children and their mothers. For the final analysis 264 questionnaires were used after eliminating questionnaires with incomplete responses. Data were analyzed using the SPSS 18.0 program. Results: The mean score for mother's child-rearing attitude was $3.31{\pm}0.25$ out of 5 points, for hierarchical language control styles ($2.76{\pm}0.62$), commanding ($1.95{\pm}0.58$), and humanistic ($2.48{\pm}0.62$) out of 5 points, and for child's social competence, $3.50{\pm}0.34$ out of 5 points. Negative correlations were found between commanding language control styles and child's social competence (r=-.34, p<.001), and between commanding language control style and mother's child-rearing attitude (r=-.50, p<.001). Conclusion: The results demonstrate the importance of the quality of mother's child-rearing attitude and language control styles for child's social competence. It is suggested that promotion programs to enhance preschool child's social competence should be developed in conjunction with the parenting related environment.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1172-1173
• /
• 2008

At the moment, the control ability of wind farms is a prime research concern for the grid integration of large wind farms, due to their required active role in the power system. As more wind turbines are installed, the power from wind energy will start to replace conventional generation units and its influence on power systems cannot be neglected. Besides, because of the intermittent nature of wind the output power of wind turbines fluctuates according to wind speed variation. Especially an isolated power system with small capacity such like Jeju needs more systematic solutions and regulations(grid code). This paper presents the idea of approach for centralized operating wind farm strategy to regulate the wind farm power production to the reference power ordered by the system operator. The doubly fed induction generator(DFIG) can control active and reactive power in feasible range. So wind farm comprised of DFIG has the possibility of a controllable component in the power system. The presented wind farm control has a hierarchical structure with both a wind farm control level and a wind turbine control level.