• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.11
• /
• pp.1095-1103
• /
• 2014

WBAN has received great attention recently due to its versatile applicability. In this paper, antennas suitable for WBAN communication depending on the locations of mobile devices and the manufacturing of a human equivalent phantom are introduced. The effect of the body on the communication performance is largely dependent on the locations of devices. Specifically, the radiation and return loss characteristics of the antenna are greatly influenced by the characteristics of a medium existing in the near-field of an antenna. Thus, the proper WBAN antenna design is important in establishing a successful communication link between the transceivers. To consider the effect of the body on the antenna performance, the human equivalent phantom is also important factor in the WBAN antenna design and measurement. In introduction, categorization of the WBAN communication channel is introduced and antenna characteristics required for each communication channel are described. In the main subject section, several WBAN antenna design examples along with the implementation of the human equivalent phantom are discussed. In conclusion, the factors, which have to be considered in the design process, and future research are mentioned.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.2
• /
• pp.37-46
• /
• 2005

In the field of earthquake engineering, recent improvements in many areas, such as seismological source modeling, analysis of travel path effects, and characterization of local site effects on strong shaking, have led to significant advances in both code-based and more advanced procedures for evaluating earthquake ground motions. A missing link, however, is empirically verified design procedures fur assessing the effects of soil-structure interaction (SSI). Available Soil-Structure Interaction (SSI) analysis techniques range from simple substructure-type procedures to relatively sophisticated finite element procedures. The most common substructure approach for foundation-soil interaction is to use a frequency-dependent and complex-valued impedance function. This study uniquely evaluates impedance functions for two well-instrumented sites w significant inertial SSI effects using a system Identification technique. The system identification analysis results are then compared to predictions from a simple theoretical model to gain insight into the inertial interaction effect in the subject sites.

• The Journal of Korean Academy of Sensory Integration
• /
• v.13 no.2
• /
• pp.75-84
• /
• 2015

Objective : The aim of this study was to provide mechanism information of a link between arousal and sensory modulation to increase understanding of neurophysiological study. Subject : Optimal arousal state of a child is an important issue in sensory integration therapy. Limbic system and reticular formation are related to sensory modulation by sensory input. Sensory inputs processes from reticular formation to cortex via ascending reticular activation system for moderate arousal. A lot of neurotransmitters such as cholinergic neurons and monoamin neurons help this processes. Mechanism of arousal was measured by functions of central nervous system (CNS) and autonomic nervous system (ANS) using objective tools such as an electroencephalogram (EEG) and electrodermal responses. Functions of CNS and ANS showed differences between normal children and children with disabilities. Optimal sensory input using sensory integration therapy for children with disabilities helps to act reticular formation, limbic system, and cortex and to maintain appropriate arousal. Conclusion : Such quantitative studies by using neurophysiological methods provide evidence for sensory integration therapy.

• Journal of Engineering Education Research
• /
• v.12 no.2
• /
• pp.96-106
• /
• 2009

Problem-based learning has been considered as one of the effective educational methods in engineering education. However, in so far as professors who require practical insights in PBL and experiences of developing actual problems by subject, in particular, thorough understanding from experiences of PBL process as well as problem-development has not been sufficiently provided. The purpose of this paper is to present strategies focusing on problem design for PBL on engineering education. In order to do this, a literature review and a qualitative case study were performed. Especially, the study intended to identify differences and gap between professors' problems-development process and its output and those of authentic PBL. Professors were found that their PBL problems had lack of authenticity, consideration on experiences of students, and realistic thinking process. Professors in PBL had difficulty to link theory into real situation. In consequence, in designing a problem, we consider the followings; first, the problem should be designed based on real design process and its output. Second, the problem should be designed and implemented in all academic years for developing student's systematic and skillful thinking process. In conclusion, more supports are needed for engineering professors to extend their experiences of designing and developing actual problems that present real experience.

• Journal of Elementary Mathematics Education in Korea
• /
• v.17 no.2
• /
• pp.245-263
• /
• 2013

Mathematical learning via projects, which enables the reconstruction of curriculum through integration and emphasizes the process of solving problems by posing questions, has attracted the attention of the department of mathematics. This research is aimed at exploring the link between mathematics and project learning by analyzing an example of student-oriented project 'the secrets of pyramid' focused on understanding 'triangle' specifically designed for forth graders. From 115-hour process of subject-oriented project, this study reinterpreted the mathematical meaning of only 24 hours directly related to mathematics, especially to figure exploration. Consequently, this problem solving involved a variety of geometric activities as a process, such as measuring an angle, constructing a triangle, etc. Thus students attempt to actively participate in the process, thereby allowing them to learn how to measure things more accurately. Moreover, project learning improved students' understanding on not only plane figures but solid figures. This indicates that by project learning, learning from given problems or contents can be extended to other mathematical areas.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.8A
• /
• pp.858-870
• /
• 2007

TCP is popular protocol for reliable data delivery in the Internet. In recent years, wireless environments with transmission errors are becoming more common. Therefore, there is significant interest in using TCP over wireless links. Previous works have shown that, unless the protocol is modified, TCP may perform poorly on paths that include a wireless link subject to transmission errors. The reason for this is the implicit assumption in TCP that all packet losses are due to congestion which causes unnecessary reduction of transmission rate when the cause of packet losses are wireless transmission errors. In this paper, we propose a new LDA that monitors the network congestion level using ROTT. And we evaluate the performance of our scheme and compare with TCP Veno, Spike scheme with NS2(Network Simulator 2). In the result of our experiment, our scheme reduces the packet loss misclassification to maximum 55% of other schemes. And the results of another simulation show that our scheme raise its transmission rate with the fairness preserved.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.7 no.4
• /
• pp.1-14
• /
• 2004

In this study, we propose Linktable based on extended TB-Tree(LTB-Tree) which can improve the performance of existing TB (Trajectory-Bundle)-tree proposed for indexing the trajectory of moving objects in GIS Applications. In addition, in order to evaluate proposed indexing scheme, we take into account as follows. At first, we select existing R*-tree, TB-tree, and LTB-tree as the subject of performance evaluation. Secondly, we make use of random data set and real data set as experimental data. Thirdly, we evaluate the performance with respect to the variation of size of memory buffer by considering the restriction of available memory of a given system. Fourth, we test them by using the experimental data set with a variation of data distribution. Finally, we think over insertion and retrieval performance of trajectory query and range query as experimental measures. The experimental results show that the proposed indexing scheme, LTB-tree, gains better performance than traditional other schemes with respect to the insertion and retrieval of trajectory query.

• Journal of the Korea Society of Computer and Information
• /
• v.18 no.10
• /
• pp.217-223
• /
• 2013

This research tries to study the effect that the welfare field training the course selection. Because of being the important place where the welfare field training trains the expert, the knowledge, value, and practical lodging tries to be identify instructed. In this aspect, we try to analyze about the extend of satisfaction of the actual training, that is the extent of desiring the link including the class of school subject extend of satisfaction of the department of social welfare engine, and etc. and factor about the actual training of the department of social welfare, because the welfare field training the technique is connected directly with the route. First, the individual characteristic of the social welfare and trainees is grasped. Second, the relationship of the social welfare and factor and course selection is investigated. Third, the social welfare and university (circle) lives look into whether the social welfare field training has an effect on the course selection or not.

• Journal of Information Management
• /
• v.40 no.1
• /
• pp.133-156
• /
• 2009

In this study, we link informal Web resources to KISTI NDSL's collections using automatic semantic indexing and tagging to examine the possibility of the service which recommends related documents using the similarity between KISTI's formal information resources and informal web resources. We collect and index Web resources and make automatic semantic linking through STEAK with KISTI's collections for NDSL retrieval. The macro precision which shows retrieval precision per a subject category is 62.6% and the micro precision which shows retrieval precision per a query is 66.9%. The experts' evaluation score is 76.7. This study shows the possibility of semantic linking NDSL retrieval results with Web information resources and expanding information services' coverage to informal information resources.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.5 no.9
• /
• pp.1492-1512
• /
• 2011

Due to multiple hops, mobility and time-varying channel, supporting delay sensitive real-time traffic in wireless local area network-based (WLAN) mesh networks is a challenging task. In particular for real-time traffic subject to medium access control (MAC) layer control overhead, such as preamble, carrier sense waiting time and the random backoff period, the performance of real-time flows will be degraded greatly. In order to support real-time traffic, an efficient adaptive packet scheduling (APS) scheme is proposed, which aims to improve the system performance by guaranteeing inter-class, intra-class service differentiation and adaptively adjusting the packet length. APS classifies incoming packets by the IEEE 802.11e access class and then queued into a suitable buffer queue. APS employs strict priority service discipline for resource allocation among different service classes to achieve inter-class fairness. By estimating the received signal to interference plus noise ratio (SINR) per bit and current link condition, APS is able to calculate the optimized packet length with bi-dimensional markov MAC model to improve system performance. To achieve the fairness of intra-class, APS also takes maximum tolerable packet delay, transmission requests, and average allocation transmission into consideration to allocate transmission opportunity to the corresponding traffic. Detailed simulation results and comparison with IEEE 802.11e enhanced distributed channel access (EDCA) scheme show that the proposed APS scheme is able to effectively provide inter-class and intra-class differentiate services and improve QoS for real-time traffic in terms of throughput, end-to-end delay, packet loss rate and fairness.