• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2067-2080
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• 2016

Cooperative spectrum sensing (CSS) for vacant licensed bands is one of the key techniques in cognitive radio networks. Currently, sequential probability ratio test scheme (SPRT) is considered as a powerful soft decision approach to improve the sensing result for CSS. However, SPRT assumes all secondary users (SU) are honest, and thus offering opportunities for malicious SUs to launch the spectrum sensing data falsification attack (SSDF attack). To combat such misbehaved behaviors, recent efforts have been made to trust mechanism. In this paper, we argue that powering SPRT with traditional trust mechanism is not enough. Dynamic SSDF attackers can maintain high trust in an alternant process of submitting honest or false sensing data, resulting in difficultly detecting them. Noting that the trust value of dymamic SSDF attackers behave highly volatile, a novel trusted SPRT scheme (VSPRT) based on volatility decay analysis is proposed in this paper to mitigate the harmful effect of dynamic SSDF attackers in the process of the soft-decision data fusion, and thus improving the accuracy of the final sensing result. Simulation results show that the VSPRT scheme outperforms the conventional SPRT schemes.

• Korean Management Science Review
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• v.24 no.2
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• pp.157-176
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• 2007

Fuzzy cognitive map(FCM) has long been used as an effective way of constructing the human's decision making process explicitly. By taking advantage of this feature, FCM has been extensively used in providing what-if solutions to a wide variety of business decision making problems. In contrast, the goal-seeking analysis mechanism by using the FCM is rarely observed in literature, which remains a research void in the fields of FCM. In this sense, this study proposes a new type of the FCM-based goal-seeking analysis which is based on utilizing the genetic algorithm. Its main recipe lies in the fact that the what-if analysis as well as goal-seeking analysis are enabled very effectively by incorporating the genetic algorithm into the FCM-driven inference process. To prove the empirical validity of the proposed approach, valid questionnaires were gathered from a number of experts on software sales, and analyzed statistically. Results showed that the proposed approach is robust and significant.

• Journal of Korean Academy of Nursing
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• v.26 no.3
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• pp.678-687
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• 1996

Smoking is considered to be one of the important risk factors associated with various health problems. Thirty seven million people in America quit smoking in the past decade, with 90% quitting on their own(Americal Heart Association, 1986). According to McAlister(1975), 70% of smokers reported that they adopted a self-help smoking cessation approach rather than a formal treatment program. In our country, although, auccessful exsmokers have used, are not available, concerns about smoking cessation have increased, recently, due to changes in social and political attitudes to health promotion. This study was conducted to help smokers who had made a decision to adopt a self-helf smoking cessation approach instead of depending on a formal treatment program. It provided a structurd way for sucessful smoking cessation by identifying change mechanism factors which have been commonly used by smokers. The subjects selected for this study were 155 university students between 20 and 29. Years of age the results from the analysis of the collected data showed that seven factors in the self-help change processes significant, and they are named, Stimulus Control, Self-Determination, Information Management, Reinforcement Management, Helpful Relationships, Dramatic Relief, and Cognitive Restructuring. All of the factors except Self-Determination represent the same change mechanisms which are proposed by Prochaska et at.(1988). Self-Determination uniformly includes items belonging to various change processes. Therefore, it might be an transitional factor including strategies related to both cognitive and behavioral dimensions. In spite of this, noted that one item which gives meaning of Self-Determination shows the highest factor loading, it is named Self-Determination.

• Korean Journal of Psychosomatic Medicine
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• v.21 no.2
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• pp.132-139
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• 2013

Objectives: The aims of this study were to know the prevalence of cognitive disorders in patients with thyroid cancer, and identify related variables to them. Methods: Subjects were consisted of fourty-two patients with thyroid cancer, who were admitted for radioiodine ablative therapy at 6-12 months after total thyroidectomy. The data were obtained from interviews about history and assessments of depression and cognitive function(Korean Version of the Montreal Cognitive Assessment, MoCA-K). Results: 1) Among subjects, those with below 22 of total score of the MoCA-K were twenty-one(50.0%). 2) Upon age, education, Pre-radioiodine therapy thyroid stimulating hormone(TSH), there were statistically significant difference between subgroup with above 23 of the total MoCA-K score and those below 22. 3) The total scores of the MoCA-K in subjects had significant correlation with age, education, comorbidity, Pre-radioiodine therapy TSH, total score of the HDRS-17. Conclusions: Cognitive disorders were more prevalent among patients with thyroid cancer before radioiodine therapy. Therefore, further study should be needed to clarify the mechanism for the cognitive disorders in thyroid cancer. Furthermore, physicians should pay attention to the cognitive function and prepare preventative measures for cognitive disorder during management of thyroid cancer.

• 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.

• Korean Journal of Biological Psychiatry
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• v.23 no.3
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• pp.108-115
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• 2016

Aggression and aggressive behaviors, often explained as harmful social interaction with the intention of hurting or inflicting damage upon another, have been considered as an adaptive mechanism from the evolutionary psychological point of view. However, various studies on aggression and aggressive behaviors have been done with psychopathological approach as the extreme aggressive behaviors may harm themselves and others at the same time. Recently, researchers have attempted to explain aggression in terms of neurobiological substrates rather than based on traditional psychopathological and/or behavioral concept. In this regard, there have been findings of differences in neurotransmitters and their receptors, and genetic polymorphisms. In this review article, we provide a brief overview of the literature about seven most frequently reported neurotransmitters including neurohormones (serotonin, norepinephrine, dopamine, gamma-aminobutyric acid, nitric oxide, oxytocin and vasopressin) and an associated enzyme (monoamine oxidase A), which are known to be related with aggression and aggressive behaviors.

• Molecules and Cells
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• v.40 no.7
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• pp.450-456
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• 2017

Mammalian physiology and behavior are regulated by an internal time-keeping system, referred to as circadian rhythm. The circadian timing system has a hierarchical organization composed of the master clock in the suprachiasmatic nucleus (SCN) and local clocks in extra-SCN brain regions and peripheral organs. The circadian clock molecular mechanism involves a network of transcription-translation feedback loops. In addition to the clinical association between circadian rhythm disruption and mood disorders, recent studies have suggested a molecular link between mood regulation and circadian rhythm. Specifically, genetic deletion of the circadian nuclear receptor Rev-$erb{\alpha}$ induces mania-like behavior caused by increased midbrain dopaminergic (DAergic) tone at dusk. The association between circadian rhythm and emotion-related behaviors can be applied to pathological conditions, including neurodegenerative diseases. In Parkinson's disease (PD), DAergic neurons in the substantia nigra pars compacta progressively degenerate leading to motor dysfunction. Patients with PD also exhibit non-motor symptoms, including sleep disorder and neuropsychiatric disorders. Thus, it is important to understand the mechanisms that link the molecular circadian clock and brain machinery in the regulation of emotional behaviors and related midbrain DAergic neuronal circuits in healthy and pathological states. This review summarizes the current literature regarding the association between circadian rhythm and mood regulation from a chronobiological perspective, and may provide insight into therapeutic approaches to target psychiatric symptoms in neurodegenerative diseases involving circadian rhythm dysfunction.

• Korean Journal of Radiology
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• v.22 no.12
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• pp.2052-2061
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• 2021

Objective: The role of preoperative overt hepatic encephalopathy (OHE) in the neurophysiological mechanism of cognitive improvement after liver transplantation (LT) remains elusive. This study aimed to explore changes in sub-regional thalamic functional connectivity (FC) after LT and their relationship with neuropsychological improvement using resting-state functional MRI (rs-fMRI) data in cirrhotic patients with and without a history of OHE. Materials and Methods: A total of 51 cirrhotic patients, divided into the OHE group (n = 21) and no-OHE group (n = 30), and 30 healthy controls were enrolled in this prospective study. Each patient underwent rs-fMRI before and 1 month after LT. Using 16 bilateral thalamic subregions as seeds, we conducted a seed-to-voxel FC analysis to compare the thalamic FC alterations before and after LT between the OHE and no-OHE groups, as well as differences in FC between the two groups of cirrhotic patients and the control group. Correction for multiple comparisons was conducted using the false discovery rate (p < 0.05). Results: We found abnormally increased FC between the thalamic sub-region and prefrontal cortex, as well as an abnormally decreased FC between the bilateral thalamus in both OHE and no-OHE cirrhotic patients before LT, which returned to normal levels after LT. Compared with the no-OHE group, the OHE group exhibited more extensive abnormalities prior to LT, and the increased FC between the right thalamic subregions and right inferior parietal lobe was markedly reduced to normal levels after LT. Conclusion: The renormalization of FC in the cortico-thalamic loop might be a neuro-substrate for the recovery of cognitive function after LT in cirrhotic patients. In addition, hyperconnectivity between thalamic subregions and the inferior parietal lobe might be an important feature of OHE. Changes in FC in the thalamus might be used as potential biomarkers for recovery of cognitive function after LT in cirrhotic patients.

• Journal of Educational Research in Mathematics
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• v.15 no.4
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• pp.461-488
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• 2005

This article presents new perspectives for classification of students' mathematical errors on the basis of experiential structuralism. Experiential structuralism's mechanism gives us new insights on mathematical errors. The hard core of mechanism is consist of 6 autonomous capacity spheres that are responsible for the representation and processing of different reality domains. There are specific forces that are responsible for this organization of mind. There are expressed in terms of a set of five organizational principles. Classification of mathematical errors is ascribed by the theory to the interaction between the 6 autonomous capacity spheres. Different types of classification require different autonomous capacity spheres. We can classify mathematical errors in the domain of linear function problem solving comparing cognitive psychological mechanism of experiential structuralism.

• Korean Journal of Cognitive Science
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• v.10 no.3
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• pp.1-15
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• 1999

Based on known physiological and psychophysical results, a neural network model for visual selection, called FeaureGate is proposed. The model consists of a hierarchy of spatial maps. and the flow of information from each level of the hierarchy to the next is controlled by attentional gates. The gates are jointly controlled by a bottom-up system favoring locations with unique features. and a top-down mechanism favoring locations with features designated as target features. The present study focuses on the top-down mechanism of the FeatureGate model that produces results similar to Moran and Desimone's (1985), which many current models have failed to explain, The FeatureGate model allows a consistent interpretation of many different experimental results in visual attention. including parallel feature searches and serial conjunction searches. attentional gradients triggered by cuing, feature-driven spatial selection, split a attention, inhibition of distractor locations, and flanking inhibition. This framework can be extended to produce a model of shape recognition using upper-level units that respond to configurations of features.