• Journal of KIISE
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• v.43 no.12
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• pp.1412-1419
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• 2016

In cognitive radio sensor networks (CRSNs), secondary users (SUs) can occupy licensed bands opportunistically without causing interferences to primary users (PUs). SUs perform spectrum sensing to detect the presence of PUs. Sensing time is a critical parameter for spectrum sensing that can yield a tradeoff between sensing performance and secondary throughput. In this study, we investigate new approaches for spectrum sensing by exploring the tradeoff from a) spectrum sensing for PU detection (SSPD) and b) spectrum sensing for secondary throughput (SSST). In the proposed scheme, the first sensing result of the current frame determines the dynamic performance of the second spectrum sensing. Energy constraint in CRSNs leads to maximized network energy efficiency via optimization of sensing time. Simulation results show that the proposed scheme of SSPD and SSST improves network performance in terms of energy efficiency and secondary throughput, respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.4
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• pp.632-650
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• 2013

The paper considers a spectrum sharing cognitive radio (CR) network coexisting with a primary network under the average interference power constraint. In particular, the secondary user (SU) is assumed to carry delay-sensitive services and thus shall satisfy a given delay quality-of-service (QoS) constraint. The secondary receiver is also assumed to be equipped with multiple antennas to perform maximal ratio combining (MRC) to enhance SU performance. We investigate the effective capacity of the SU with MRC diversity under aforementioned constraints in Nakagami fading environments. Particularly, we derive the optimal power allocation to achieve the maximum effective capacity of the SU, and further derive the effective capacity in closed-form. In addition, we further obtain the closed-form expressions for the effective capacities under three widely used power and rate adaptive transmission schemes, namely, optimal simultaneous power and rate adaptation (opra), truncated channel inversion with fixed rate (tifr) and channel inversion with fixed rate without truncation (cifr). Numerical results supported by simulations are presented to consolidate our studies. The impacts on the effective capacity of various system parameters such as the number of antennas, the average interference power constraint and the delay QoS constraint are investigated in detail. It is shown that MRC diversity can significantly improve the effective capacity of the SU especially for cifr transmission scheme.

• Journal of the Korea Convergence Society
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• v.9 no.1
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• pp.241-251
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• 2018

The study is a preliminary study of the effectiveness of the structured cognitive behavioral arbitration program targeting elementary school students who perform high risk problems based on schools for convergence with local communities. The program is designed to be practiced by semi-trained professionals. To screen high-risk students, total 102 students were tested K-CBCL and those who scored over 60T on problem behavior syndrome scale were recruited. 32 students were selected and devided into intervention group and control group. Intervention group was received 90-minutes-sessions per week, for nine weeks. The program was done by graduate students and undergraduate students majoring counseling and supervised by school psychologist. The internalization group showed significantly lower score in Internalization, anxiety/depression, and externalization group showed externalization, aggressive behavior. but mixed group didn't showed significantly lower score. Implications of the results, limitations and suggestions for future study were mentioned.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.315-316
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• 2007

This paper presents a new methodology to improve movement database for a humanoid robot. The database is initially full of human motions so that the kinetics characteristics of human movement are immanent in it. then, the database is updated to the pseudo-optimal motions for the humanoid robot to perform more natural motions, which contain the kinetics characteristics of robot. for this, we use the evolutionary algorithm. the methodology consists of two processes : (1) the offline imitation learning of human movement and (2) the online generation of natural motion. The offline process improve the initial human motion database using the evolutionary algorithm and inverse dynamics-based optimization. The optimization procedure generate new motions using the movement primitive database, minimizing the joint torque. This learning process produces a new database that can endow the humanoid robot with natural motions, which requires minimal torques. In online process, using the linear combination of the motion primitive in this updated database, the humanoid robot can generate the natural motions in real time. The proposed framework gives a systematic methodology for a humanoid robot to learn natural motions from human motions considering dynamics of the robot. The experiment of catching a ball thrown by a man is performed to show the feasibility of the proposed framework.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2389-2396
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• 2014

Spectrum handoff is the process of exchanging progressing data transmission from the current channel to another idle channel. The essential goal of spectrum handoff in CR(Cognitive Radio) networks is to perform consistent data transmission while sustaining performance of ongoing transmission of secondary users. This handoff procedure can cause additional latency that eventually affects on the performance of CR transmission. Channel prediction method is expected to avoid the disruption to primary users and to reduce the handoff latency. In this paper, adaptive channel prediction is proposed to cope with time-varying channel and an adaptive channel prediction based proactive handoff procedure is designed to enhance data transmission performance.

• Physical Therapy Korea
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• v.14 no.2
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• pp.1-10
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• 2007

The purpose of this experiment was to investigate the applicability of audio-visual modeling for improving the efficiency of rehabilitative programs by analyzing the effects of observing these various models on the capacity of stroke patients to perform upper limb activities. Twenty-one stroke patients participated in the experiment and were randomly assigned to either task modeling, sport modeling, or control group. During 2 weeks of intervention, subjects in all groups participated in the physical practice of experimental tasks. These tasks comprised of a Nine Hole Peg Test, the Jebsen-Taylor Hand Function tests, and locomotion. These tasks were performed 5 days a week, 30 min per day. In addition to the physical practice, the task modeling group observed a model performing experimental tasks and locomotive activities for 20 min, while the sport modeling group observed a model performing various sport activities for 20 min. Subjects' ability to perform the experimental tasks was measured 3 times, before, immediately after, and 1 week after the intervention. Analyses of the capacity to perform upper extremity activities displayed significant improvement from the pre-test to immediate and delayed post-tests in all groups. However, the amount of improvement was the highest in the task modeling group. The task modeling group was superior to the control group in the post-test of all experimental tasks, whereas the sport modeling group did not display significant differences from the control group. These results suggest that audio-visual modeling can be used as an effective cognitive intervention for facilitating the rehabilitation of stroke patients, and its rehabilitative effect can be maximized when the program is comprised of performance scenes directly related to the target task.

• The Journal of Korean society of community based occupational therapy
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• v.9 no.2
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• pp.23-31
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• 2019

Objective : The purpose of this study is to repeatedly conduct task-oriented training in scopolamine-induced dementia rats and as a result observe changes in the content of acetylcholine, a marker of cognitive function and central nervous system plasticity, to identify the improvement effect of dementia. Methods : It consisted of two groups. One group I was that did not perform task-oriented training in scopolamine-induced dementia rats and the other group II was that performed task-oriented training. Task-oriented training involved stretching, grasping and moving arms and walking obstacles on the legs. We performed a quantified passive avoidance test in the measurement of memory for cognitive function and compared the change in the content of acetylcholine for the plasticity of the central nervous system. Results : The results of the study are as follows: First, there was a significant improvement in cognitive function since the 4th days after task-oriented training of scopolamine-induced dementia rats(.00). Second, task-oriented training applied to scopolamine-induced dementia rats showed a significant increase in acetylcholine content. Conclusion : In this study, task-oriented training, which is often performed on senile dementia patients during occupational therapy intervention, was scientifically demonstrated in scopolamine-induced dementia rats by enhancement of cognitive function through memory improvement and increase in the content of acetylcholine confirming central nervous system plasticity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2305-2315
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• 2015

Frequency resource value is growing more and more with the development of the wireless communication. With the advent of the current information society comes a serious shortage of frequency resource, as the amount of supply is far from meeting its demands. Thus, cognitive radio (CR) technique is receiving more attention as a way to make use of the temporarily unoccupied frequency resource. In this paper we propose a novel out-of-band spectrum sensing and dynamic channel access scheme for frequency hopping-based cognitive radio ad-hoc networks. At the beginning of each current channel hopping time, member nodes perform spectrum sensing for the next hopping channel. Based on the proposed collision free primary detection notification, member nodes can determine whether they should execute a hopping time extension procedure of the current channel or not. When the primary detected hopping channel is re-idled, the hopping pattern recovery procedure is performed. In this paper we evaluated the performance of the proposed dynamic sensing and hopping channel extension mechanism for the various wireless network conditions. As a result, we show that the proposed method can increase channel utilization and provide reliable channel management operation.

• Journal of The Korean Association For Science Education
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• v.25 no.4
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• pp.503-513
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• 2005

The purpose of this study was to analyze the generating processes of scientific emotion, that appears during the generation of biological hypotheses. To perform the study, a tentative model was set up through pilot test, a think-aloud training procedure was planned and a standardized interview instrument was developed before getting protocols. In this study, 8 college students were selected to bring out protocol through the method of think-aloud, retrospective debriefing, focused interview and observing. As the result of analysis of the collected protocol through coding scheme, 4 types of process for scientific emotion-generating were sorted out. First type was a basic process which was a feeling process in prior to recognition. Second type was a retrospective process that explains the process of retrospect for emotional memory based on the past. Third type was a cognitive process and it explains emotion that occurs during thinking process to achieve cognitive goal. Fourth type was an attribution process and it explains that emotion is generated in the process of attribution for cognitive goal's achievement. These types of process of scientific emotion-generating can contribute the basis for developing cognitive model of EBL (Emotional Brain-based Learning) strategy.

• Journal of The Korean Association For Science Education
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• v.18 no.4
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• pp.503-516
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• 1998

The purpose of the present study was to evaluate some variables, such as learner's cognitive characteristics and a training-program emphasized proportional logic, in proportional reasoning development. Seven hundred and ninety students in junior high schools were enrolled as subjects for the study which investigated learner's cognitive characteristics in proportional reasoning development and asked to perform tests of logical thinking, card sorting, planning, mental capacity, cognitive style, brain lateralization, information processing pattern and scientific reasoning. In addition, one hundred and thirty-three students who failed to solve proportional thinking items were administered a training program which has been applied to improve the subjects' proportional reasoning skills. The results showed a significant higher correlation between subjects' performance score on proportional thinking test, and their age and scores on scientific reasoning test, mental capacity, information processing test and perseveration errors on card sorting test. Also, the training program applied in this study showed an effective result in developing subjects' proportional reasoning skills. Further, this study may serve as a suggestion in the efforts to investigate factors of proportional thinking development and a contribution for the future research in other logical thinking development.