• Journal of Institute of Control, Robotics and Systems
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• v.21 no.11
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• pp.1027-1033
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• 2015

For the attitude control of spacecraft, two variable-speed control moment gyros are proposed as main actuators in the article. Since a variable-speed control moment gyro (VSCMG) makes two control torques (gyroscopic torque and reaction torque), two VSCMGs are sufficient for controlling 3-axes attitude. Additionally, there are no singular conditions for two non-parallel VSCMGs. Since gyroscopic torque is usually much greater than reaction torque, the control performances of approximately 3 axes may not be the same. However, several missions can be accomplished by controlling two axes. For such missions, a selective axes control method is proposed. The method selects two axes for a certain task and controls the attitude of the selected axes. For the remaining axis, angular speed is controlled for stabilization. A hardware-in-the-loop simulation has been used to test VSCMG modules and to verify the proposed method. Two VSCMGs can be alternative actuators for small satellites.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.297-305
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• 2006

High-rate wireless personal area network (HR-WPAN) has been standardized by the IEEE 802.15.3 task group (TG). To support multimedia services, the IEEE 802.15.3 TG adopts a time-slotted medium access control (MAC) protocol controlled by a central device. In the time division multiple access (TDMA)-based wireless packet networks, the packet scheduling algorithm plays a key role in quality of service (QoS) provisioning for multimedia services. In this paper, we propose an adaptive cross-layer packet scheduling method for the TDMA-based HR-WPAN. Physical channel conditions, MAC protocol, link layer status, random traffic arrival, and QoS requirement are taken into consideration by the proposed packet scheduling method. Performance evaluations are carried out through extensive simulations and significant performance enhancements are observed. Furthermore, the performance of the proposed scheme remains stable regardless of the variable system parameters such as the number of devices (DEVs) and delay bound.

• Journal of the Korean Home Economics Association
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• v.47 no.5
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• pp.1-11
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• 2009

The purpose of this study was to examine the relationship between preschoolers’ self-perception, peer competence and giftedness. The subjects in this study were 101 preschoolers between the ages of 4 and 5 who attended childcare centers and private kindergartens in Pohang city area. The major findings of this study were as follows: Firstly, there were significant negative correlation between cognitive ability variables of self-perception and aggressive and asocial variables of peer competence. Secondly, there were significant positive correlation between cognitive ability variables of self-perception and humor variables of giftedness. Furthermore there were significant positive correlation between mother acceptance variables of selfperception and logical thinking, task commitment and humor variables of giftedness. Finally, there were significant negative correlation between hyper-distractible variables of peer competence and independence variables of giftedness.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.1023-1033
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• 2012

An underwater planar covering problem is studied where the coverage region consists of polygonal cells, and line sweep motion is used for coverage. In many subsea applications, sidescan sonar has become a common tool, and the sidescan sonar data is meaningful only when the sonar is moving in a straight line. This work studies the optimal line sweep coverage where the sweep paths of the cells consist of straight lines and no turn is allowed inside the cell. An optimal line sweep coverage solution is presented when the line sweep path is parallel to an edge of the cell boundary. The total time to complete the coverage task is minimized. A unique contribution of this work is that the optimal sequence of cell visits is computed in addition to the optimal line sweep paths and the optimal cell decomposition.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.4
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• pp.459-468
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• 2015

Although defense standardization is recently becoming more and more active, there are still many obstacles to achieve attainments as planned. On the other hand, national standardization already has been applied as a mandatory rule in the overall industries and R&D programs and is well supported by systematic and specialized national basis. Furthermore, advanced countries, such as U.S.A., England and NATO, are considering defense standardization as a essential element to achieve low cost and highly efficient acquisition system and to enhance interoperability among the allied forces. This study aims to form public opinion in support of importance of defense standardization and to provide the vision and various implementation tasks for improving defense standardization outcome.

• Journal of information and communication convergence engineering
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• v.2 no.1
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• pp.32-35
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• 2004

Human ability to perceive colors is a very subjective matter. The task of measuring and analyzing appropriate colors from colored images, which matches human sensitivity for perceiving colors, has been a challenge to the research community. In this paper we propose a novel approach, which involves the use of fuzzy logic and reasoning to analyze the RGB color intensities extracted from sensory inputs to understand human sensitivity for various colors. Based on this approach, an intelligent system has been built to predict the subject's personality. The results of experiments conducted with this system are discussed in the paper.

• Journal of Power Electronics
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• v.10 no.6
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• pp.660-666
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• 2010

This paper presents the approach followed to develop a course that introduces reliability into the design of power electronics converters. The course is part of the curriculum of a master of science in electrical engineering program, and it is aimed at providing reliability tools that can be used in a straightforward manner, while avoiding the mathematical intricacies. The reliability calculations are performed according to the Military Handbook 217, using the evaluation version of a commercial software package which greatly reduces the computational burden usually associated with this task. The course assessment shows that, after attending the course, students were able to improve the mean time between failures in a power-electronics converter, from a minimum of 5%, up to 100%.

• Annual Conference of KIPS
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• 2019.05a
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• pp.542-544
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• 2019

Changes in a person's health affect one's lifestyle and work activities. According to the World Health Organization (WHO), abnormal activity is growing faster in people aged 60 or more than any other age group in almost every country. This trend steadily continues and expected to increase further in the near future. Abnormal activity put these people at high risk of expected incidents since most of these people live alone. Human abnormal activity analysis is a challenging, useful and interesting problem among the researchers and its particularly crucial task in life and health care areas. In this paper, we discuss the problem of abnormal activities of old people lives alone at home. We propose Convolutional Neural Network (CNN) based model to detect the abnormal behaviors of elderlies by utilizing six simulated action data from daily life actions.

• International journal of advanced smart convergence
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• v.10 no.4
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• pp.22-29
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• 2021

For web application vulnerability diagnosis, from the development stage to the operation stage, it is possible to stably operate the web only when there is a policy that is commonly applied to each task through diagnosis of vulnerabilities, removal of vulnerabilities, and rapid recovery from web page damage. KISA presents 28 evaluation items for technical vulnerability analysis of major information and communication infrastructure. In this paper, we diagnose the vulnerabilities in the automobile goods shopping mall website and suggest security measures according to the vulnerabilities. As a result of diagnosing 28 items, major vulnerabilities were found in three items: cross-site scripting, cross-site request tampering, and insufficient session expiration. Cookie values were exposed on the bulletin board, and personal information was exposed in the parameter values related to passwords when personal information was edited. Also, since the session end time is not set, it was confirmed that session reuse is always possible. By suggesting security measures according to these vulnerabilities, the discovered security threats were eliminated, and it was possible to prevent breaches in web applications and secure the stability of web services.

• Journal of Korea Multimedia Society
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• v.24 no.12
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• pp.1693-1707
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• 2021

The purpose of this study was to improve the experience of visiting obstetrics and gynecology of single women. After analyzing previous studies on Korean single women's perception of visiting obstetrics and gynecology, Contextual Interviews and Cultural Probes were conducted on single women in their 20s who visited obstetrics and gynecology. Based on this, personas were constructed to solidify the direction of problem solving by identifying the behavioral patterns and characteristics of single women. In this study, factors that hinder unmarried women's visits to obstetrics and gynecology and improvement measures were derived based on the information obtained using service design tools such as User Journey Mapping and Stakeholders' Map. Afterwards, a preference survey was conducted to increase the persuasiveness of the proposed method. The follow-up research task is to produce and propose the derived solution as a prototype that can be used in the actual field, and then proceed with user evaluation.