• Journal of information and communication convergence engineering
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• v.9 no.4
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• pp.391-395
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• 2011

Cognitive radio (CR) technique is a useful tool for improving spectrum utilization by detecting and using the vacant frequency bands while avoiding interference to the primary user. The sensing performance in a CR network can be improved by allowing some CR users to perform cooperative spectrum sensing. In this paper, we propose a new sensing algorithm that utilizes an adaptive energy threshold for cooperative spectrum sensing in which a changeable energy threshold is adopted by the CR users for improving local sensing performance. Through the proposed scheme, the reliability of global decision can be enhanced mainly due to the improvement in local sensing performance.

• YAKHAK HOEJI
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• v.57 no.5
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• pp.323-329
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• 2013

This study was designed to determine and compare the cognitive enhancing effect of various Codonopsis lanceolata extracts by steaming, fermentation and high hydrostatic pressure process. We prepared water extract of C. lanceolata, steamed C. lanceolata, steamed and fermented C. lanceolata and C.lanceolata by high hydrostatic pressure process and fermentation. Cognitive enhancing effect of extracts was evaluated in scopolamine-induced memory impairment mice using by passive avoidance test and Morris water maze tests. MTT assay was conducted to investigate neuroprotective effect on glutamate induced cell death in HT22 cells. Steamed and fermented C. lanceolata water extract decreased escape latency in Morris water maze test and increased the latency time of the passive avoidance test compared to other extracts. Furthermore, the steamed and fermented C. lanceolata water extract showed neuroprotective effect. These results suggest that steaming and fermentation process more improve cognitive enhancing effect of C. lanceolata than other process.

• Korean Journal of Pharmacognosy
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• v.44 no.1
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• pp.41-46
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• 2013

Alzheimer's disease (AD), most common form of dementia is characterized that memory deficit and loss of cognitive function. The Codonopsis lanceolata (C.lanceolata) was treated by high hydrostatic pressure process and fermentation. This study was evaluated cognitive enhancing effect C.lanceolata extract by high hydrostatic pressure process and fermentation and compared with common C.lanceolata extract using Morris water maze and passive avoidance test. And their neuroprotective effect on glutamate induced oxidative stress in HT22 cell was investigated by MTT assay. High hydrostatic pressure process and fermented C.lanceolata extract (HFCE) and common C.lanceolata extract (CCE) (100 and 300 mg/kg) were administered to mice. Results showed HFCE enhanced cognitive function than CCE as shown by decrease in escape latency time. HFCE increased the latency time of the passive avoidance test compared to CCE. Furthermore, HFCE showed significant neuroprotective effect against glutamate cytotoxicity in HT22 cells. These results indicate that high hydrostatic pressure process and fermented more improve spatial cognitive ability of C. laanceolata.

• YAKHAK HOEJI
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• v.58 no.5
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• pp.287-293
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• 2014

Alzheimer's disease (AD), most common form of dementia is characterized that memory deficit and loss of cognitive function. This study was evaluated cognitive enhancing effect of water and ethanol extracts of Codonopsis lanceolata and compared using Morris water maze and passive avoidance test. The water and 70% ethanol extracts (100, 300 and 500 mg/kg) were administered to mice. The neuroprotective effect on glutamate-induced cell death in HT22 cells was additionally investigated using MTT assay. Results showed 70% ethanol extract of Codonopsis lanceolata enhanced cognitive function than water extract, as shown by decrease in escape latency time in Morris water maze test. In passive avoidance test, 70% ethanol extract also increased the latency time compared to the water extract. Furthermore, 70% ethanol extract significantly protected neuronal cell against glutamate cytotoxicity and showed higher than neuroprotective effect of water extract. These results indicate that 70% ethanol extract more improve spatial cognitive ability and protected neuronal cells than water extract.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.7
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• pp.599-611
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• 2016

This paper proposes a cognitive engine platform that enables dynamic spectrum access(DSA) based on a spectrum sharing system for the military tactical network environment. The current military tactical wireless communication system is increasing need to secure a supplementary wireless spectrum to ensure that multiple wireless networks for different weapon systems co-exist, so that tactical wireless communication between the same or different systems can be operated effectively. This paper examined policy development and research activities engaged by the U.S. and European countries on wireless spectrum sharing to secure more spectrum. It also introduces the current status of cognitive engine development, which is the core technology of tactical wireless communication for DSA. In addition, based on the investigation performed into the latest trends, we propose a platform structure for a cognitive engine based on a spectrum sharing method where more frequencies can be added for tactical radio communication, so that DSA can be realized, and wireless networks of different weapon systems can co-exist.

• Journal of Communications and Networks
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• v.14 no.2
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• pp.188-194
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• 2012

Cognitive networks (CNs) are capable of enabling dynamic spectrum allocation, and thus constitute a promising technology for future wireless communication. Whereas, the implementation of CN will lead to the requirement of an increased energy-arrival rate, which is a significant parameter in energy harvesting design of a cognitive user (CU) device. A well-designed spectrum-sensing scheme will lower the energy-arrival rate that is required and enable CNs to self-sustain, which will also help alleviate global warming. In this paper, spectrum sensing in a multi-user cognitive ad hoc network with a wide-band spectrum is considered. Based on the prospective spectrum sensing, we classify CN operation into two modes: Distributed and centralized. In a distributed network, each CU conducts spectrum sensing for its own data transmission, while in a centralized network, there is only one cognitive cluster header which performs spectrum sensing and broadcasts its sensing results to other CUs. Thus, a wide-band spectrum that is divided into multiple sub-channels can be sensed simultaneously in a distributed manner or sequentially in a centralized manner. We consider the energy consumption for spectrum sensing only of an analog-to-digital convertor (ADC). By formulating energy consumption for spectrum sensing in terms of the sub-channel sampling rate and whole-band sensing time, the sampling rate and whole-band sensing time that are optimal for minimizing the total energy consumption within sensing reliability constraints are obtained. A power dissipation model of an ADC, which plays an important role in formulating the energy efficiency problem, is presented. Using AD9051 as an ADC example, our numerical results show that the optimal sensing parameters will achieve a reduction in the energy-arrival rate of up to 97.7% and 50% in a distributed and a centralized network, respectively, when comparing the optimal and worst-case energy consumption for given system settings.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12A
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• pp.1014-1022
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• 2009

In this paper, interference analysis is carried out to obtain the operating criterion and coexistence condition between digital television devices and cognitive radio-based mobile wimax devices in the UHF (Ultra High Frequency) broadcasting frequency bands. To this end, an efficient interfering calculation tool known as SEAMCAT (Spectrum Engineering Advanced Monte-Carlo Analysis Tool) is employed to acquire the coexistence criterions between heterogeneous radio links operating in the same portion of spectrum. As a result, these criterions will be used to achieve interference temperature limit level applied to interference temperature model for analyzing the capacity of cognitive radio receivers accurately.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.227-231
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• 2009

The aim of the research is to focus on the cognitive principles and to achieve human-level intelligence in referring context based browser history and the Windows history. One of the major problems faced by today's computer users is insufficient and single exclusive context based reference of the browser history and the Windows history. Today we search for the browser history and Windows history in different places even though the context is the same. For e.g., When working on a research paper or preparing a business presentation, a user may require to refer many web sites on the internet and various documents on the local computer. The browser can provide only time based history. The windows document history is also time based and limited to list only few documents. Hence, we propose a tool "Cognitive Based Context Aware Reference History Management Tool" which helps to access the exclusive reference of context and time based history in one place. The tool also proposes to store image history with urls and classifies images of a specific topic accessed in different time, bookmarks management and cross browser history management. These features are very useful as we can access all related documents (doc, docx, ppt, pptx, pdf, txt, and html), web pages, images and bookmarks in one place. The tool uses the cognitive principles like classification and association to achieve the purpose.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.8
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• pp.1606-1612
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• 2012

Cognitive radio technology enables us to utilize the extra spectrum which is not used by the primary users by sensing the channel condition. To use such an extra spectrum, spectrum allocation is one of the important issues in the cognitive radio networks. The network is dynamic and the available channels are changeable, and the opportunistic channel allocation is required to use the resource efficiently without interference to the primary networks. In this paper, modified proportional fairness scheduling is proposed for cognitive radio networks to satisfy the both fairness and system throughput, and the modified scheduling was designed to reduce the interference to the primary users.

• Journal of Korea Multimedia Society
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• v.20 no.2
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• pp.205-215
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• 2017

The brain magnetic resonance images (MRI) is an important imaging biomarker in Alzheimer's disease (AD) as the cerebral atrophy has been shown to strongly associate with cognitive symptoms. The decrease of volume estimates in different structures of the medial temporal lobe related to memory correlates with the decline of cognitive functions in neurodegenerative diseases. During the past decades several methods have been developed for quantifying the disease related atrophy of hippocampus from MRI. Special effort has been dedicated to separate AD and mild cognitive impairment (MCI) related modifications from normal aging for the purpose of early detection and prediction. We trained a multi-class support vector machine (SVM) with probabilistic outputs on a sample (n = 58) of 20 normal controls (NC), 19 individuals with MCI, and 19 individuals with AD. The model was then applied to the cross-validation of same data set which no labels were known and the predictions. This study presents data on the association between MRI quantitative parameters of hippocampus and its quantitative structural changes examination use on the classification of the diseases.