• 한국멀티미디어학회논문지
• /
• 제24권5호
• /
• pp.684-694
• /
• 2021

Resting-state Functional Magnetic Resonance Imaging(fMRI) data detects the temporal correlations in Blood Oxygen Level Dependent(BOLD) signal and these temporal correlations are regarded to reflect intrinsic cortical connectivity, which is deactivated during attention demanding, non-self referential tasks, called Default Mode Network(DMN). The relationship between fMRI and anatomical connectivity has not been studied in detail, however, the preceded studies have tried to clarify this relationship using Diffusion Tensor Imaging(DTI) and fMRI. These studies use method that fMRI data assists DTI data or vice versa and it is used as guider to perform DTI tractography on the brain image. In this study, we hypothesized that functional connectivity in resting state would reflect anatomical connectivity of DMN and the combined images include information of fMRI and DTI showed visible connection between brain regions related in DMN. In the previous study, functional connectivity was determined by subjective region of interest method. However, in this study, functional connectivity was determined by objective and advanced method through Independent Component Analysis. There was a stronger connection between Posterior Congulate Cortex(PCC) and PHG(Parahippocampa Gyrus) than Anterior Cingulate Cortex(ACC) and PCC. This technique might be used in several clinical field and will be the basis for future studies related to aging and the brain diseases, which are needed to be translated not only functional connectivity, but structural connectivity.

• 한국통신학회논문지
• /
• 제38B권1호
• /
• pp.34-45
• /
• 2013

자가구성 능력을 가진 전술모바일애드혹 네트워크는 기간망을 사용할 수 없는 전술환경에서 단위전술부대와 중앙지휘소와의 통신연결을 제공하기 위해 사용된다. 하지만, 작전 전술부대가 임무수행을 위해 중앙지휘소로부터 장거리 위치로 이동하거나 지형적 장애물이 있는 경우에는 통신단말간 데이터링크가 단절되어 전술부대로부터 지휘소까지의 데이터 경로가 유효하지 않을 수 있다. 이러한 문제를 해결하기 위하여 본 논문에서는 ADLCoM(Autonomous Data Link Connectivity Maintenance) 구조를 제안한다. ALDCoM하에서 각 전술그룹단위는 하나이상의 GW 노드 (게이트웨이)를 갖으며 GW 노드들은 전술부대 및 지휘소 간의 데이터 링크상태를 지속적으로 확인한다. 만약 데이터링크가 단절될 가능성이 높다면 하나이상의 육상 또는 공중 무인기를 데이터링크를 위한 릴레이로서 동작하도록 요청하여 전술 부대 및 지휘소간, 또는 전술 부대간의 데이터링크의 연결을 지속적으로 유효하게 유지 시킨다. 전술환경을 모의한 시뮬레이션을 통하여 ADLCoM구조가 전술모바일애드혹망의 성능을 현저히 높일 수 있음을 보인다.

• 대한교통학회지
• /
• 제28권6호
• /
• pp.167-177
• /
• 2010

본 연구에서는 교통물류거점의 네트워크 연계성 개선효과를 분석하기 위한 방법론을 제시하였다. 기존에 개발된 노드의 연계성 산출 모형을 사용하여 공급 연계성과 체감 연계성을 정의하였고, 교통물류거점의 네트워크 연계성 분석 범위와 분석 대상 노드 설정 알고리즘을 제시하였다. 또한 교통물류거점의 네트워크 연계성 개선효과 분석 과정을 체계화하였으며, 연계성 개선사업의 효과평가 방법 및 기준을 제시하였다. 방법론을 사례 연구에 적용한 결과 적절한 결과를 도출하였으며 전국 도로 네트워크에 실제 적용 가능하다고 판단된다. 교통물류거점의 네트워크 연계성 분석 결과 값들이 어느 정도 축적된 이후에는 네트워크 연계성의 서비스수준을 판단하기 위한 추가 연구가 필요하다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1999년도 하계종합학술대회 논문집
• /
• pp.974-977
• /
• 1999

In this paper, we have proposed the hardware architecture which implements the algorithm for retaining the connectivity which prevents disconnecting in the gray-scale image thinning To perform the image thinning in a real time which find a skeleton in image, it is necessary to examine the connectivity of the skeleton in a real time. The proposed architecture finds the connectivity number in the 4-clock period. The architecture is consists of three blocks, PS(Parallel to Serial) Converter and State Generator and Ridge Checker. The PS Converter changes the 3$\times$3 gray level image to four sets of image pixels. The State Generator examine the connectivity of the central pixel by searching the data from the PS Converter. the 3$\times$3 gray level image determines. The Ridge Checker determines whether the central pixel is on the skeleton or not The proposed architecture finds the connectivity of the central pixel in a 3$\times$3 gray level image in the 4-clocks. The total circuits are verified by the design tools and operate correctly.

• 한국멀티미디어학회논문지
• /
• 제24권4호
• /
• pp.583-592
• /
• 2021

Obsessive-compulsive disorder (OCD) is a mental disorder in which a person repeated a particular thought or feels. The domain of beliefs and guilt predicted OCD symptoms. Although there were some neuroimaging studies investigating OCD symptoms, resting-state functional magnetic resonance imaging (rs-fMRI) study investigating intra-network functional connectivity associated with guilt for OCD is not reported yet. Therefore, in the current study, we assessed the differences between intra-network functional connectivity of healthy control group and OCD group using independent component analysis (ICA) method. In addition, we also aimed to investigate the correlation between changed functional connectivity and guilt score in OCD. Total 86 participants, which consisted of 42 healthy control volunteers and 44 OCD patients, acquired rs-fMRI data using the 3T MRI. After preprocessing the fMRI data, a functional connectivity was used for group independent component analysis. The results showed that OCD patients had higher score in emotion state in beliefs and lower functional connectivity in fronto-parietal network (FPN) than control group. A decrease of functional connectivity in FPN was negatively correlated with feelings of guilt in OCD. Our results suggest excessive increase in guilt negatively affect to process emotional state and behavior or cognitive processing by influencing intrinsic brain activity.

• Communications for Statistical Applications and Methods
• /
• 제12권1호
• /
• pp.241-252
• /
• 2005

In this study we suggest that the spatial correlation structure of the brain fMRI data be used to characterize the functional connectivity of the brain. For some concussion and recovery data, we examine how the correlation structure changes from one step to another in the data analyses, which will allow us to see the effect of each analysis to the spatial correlation or the functional connectivity of the brain. This will lead us to spot the processes which cause significant changes in the spatial correlation structure of the brain. We discuss whether or not we can decompose correlation matrices in terms of its causes of variations in the data.

• Journal of the Korean Data and Information Science Society
• /
• 제22권4호
• /
• pp.741-753
• /
• 2011

마이크로어레이 유전자 발현데이터인 효모데이터를 이용하여 군집분석을 실시하였다. 모형기반 군집방법, K-평균법, 중앙값 중심분포 (PAM), 자기 조직화 지도 (SOM), 계층적 Ward 군집방법을 이용하여 군집화를 실시하고, 연결성 측도 (connectivity), Dunn지수, 실루엣 측도 (silhouette)를 이용하여 각 군집방법에 대한 유효성을 측정하고 군집분석 결과를 비교하고자한다.

• International Journal of Advanced Culture Technology
• /
• 제11권1호
• /
• pp.395-402
• /
• 2023

The implementation of a hybrid network utilizing Power Line Communication (PLC) and Wi-Fi technologies has been demonstrated to improve signal strength and coverage in areas with poor connectivity due to internet shadow areas. In this study we strategically positioned Wi-Fi relays and utilized the capabilities of PLC technology to significantly improve signal strength and coverage in areas with poor connectivity. We also analyzed the effects of metallic obstacles on Wi-Fi signal propagation and proposed a solution to strengthen the signal enough to pass through them. Our experiment demonstrated the feasibility and potential of using this hybrid network in industrial scenarios for real-time data transmission. Overall, the results suggest that the use of PLC and Wi-Fi hybrid networks can be a cost-effective and efficient solution for overcoming internet connectivity challenges and has the potential to provide high-speed internet access to areas with unreliable signals.

• 대한인간공학회지
• /
• 제33권5호
• /
• pp.377-386
• /
• 2014

Objective: In this study, we used resting-state fMRI data to map differences in functional connectivity between a comprehensive set of 8 distinct cortical and subcortical brain regions in healthy controls and Internet addicts. We also investigated the relationship between resting state connectivity strength and the level of psychopathology (ex. score of internet addiction scale and score of Barratt impulsiveness scale). Background: There is a lot of evidence of relationship between Internet addiction and impaired inhibitory control. Clinical evidence suggests that Internet addicts have a high level of impulsivity as measured by behavioral task of response inhibition and a self report questionnaire. Method: 15 Internet addicts and 15 demographically similar non-addicts participated in the current resting-state fMRI experiment. For the connectivity analysis, regions of interests (ROIs) were defined based on the previous studies of addictions. Functional connectivity assessment for each subject was obtained by correlating time-series across the ROIs, resulting in $8{\times}8$ matrixs for each subject. Within-group, functional connectivity patterns were observed by entering the z maps of the ROIs of each subject into second-level one sample t test. Two sample t test was also performed to examine between group differences. Results: Between group, the analysis revealed that the connectivity in between the orbito frontal cortex and inferior parietal cortex, between orbito frontal cortex and putamen, between the orbito frontal cortex and anterior cingulate cortex, between the insula and anterior cingulate cortex, and between amydgala and insula was significantly stronger in control group than in the Internet addicts, while the connectivity in between the orbito frontal cortex and insula showed stronger negative correlation in the Internet addicts relative to control group (p < 0.001, uncorrected). No significant relationship between functional connectivity strength and current degree of Internet addiction and degree of impulsitivy was seen. Conclusion: This study found that Internet addicts had declined connectivity strength in the orbitofrontal cortex (OFC) and other regions (e.g., ACC, IPC, and insula) during resting-state. It may reflect deficits in the OFC function to process information from different area in the corticostriatal reward network. Application: The results might help to develop theoretical modeling of Internet addiction for Internet addiction discrimination.

• 디지털산업정보학회논문지
• /
• 제8권1호
• /
• pp.47-53
• /
• 2012

Sensor networks and car networks that have different structure from that of conventional TCP/IP network require extreme network environment due to frequent change of connectivity. Because such extreme network environment has characteristics like unreliable link connectivity, long delay time, asymmetrical data transfer rate, and high error rate, etc., it is difficult to perform normally with the conventional TCP/P-based routing. DTNs (delay and disruption tolerant network) was designed to support data transfer in extreme network environment with long delay time and no guarantee for continuous connectivity between terminals. This study suggests an algorithm that limits the maximum number of copying transferred message to L by improving the spray and wait routing protocol, which is one of the conventional DTNs routing protocols, and using the azimuth and density data of the mobile nods. The suggested algorithm was examined by using ONE, a DTNs simulator. As a result, it could reduce the delay time and overhead of unnecessary packets compared to the conventional spray and wait routing protocol.