• Proceedings of the Korean Society for Bioinformatics Conference
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• 2004.11a
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• pp.124-130
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• 2004

Microarray expression datasets are incessantly cumulated with the aid of recent technological advances. One of the first steps for analyzing these data under various experimental conditions is determining differentially expressed genes (DEGs) in each condition. Reasonable choices of thresholds for determining differentially expressed genes are used for the next -step-analysis with suitable statistical significances. We present a model for identifying DEGs using pathway information based on the global connectivity structure. Pathway information can be regarded as a collection of biological knowledge, thus we are tying to determine the optimal threshold so that the consequential connectivity structure can be the most compatible with the existing pathway information. The significant feature of our model is that it uses established knowledge as a reference to determine the direction of analyzing microarray dataset. In the most of previous work, only intrinsic information in the miroarray is used for the identifying DEGs. We hope that our proposed method could contribute to construct biologically meaningful network structure from microarray datasets.

• Journal of Biomedical Engineering Research
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• v.27 no.4
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• pp.170-179
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• 2006

The purpose of this study was to investigate the spatiotemporal cortical activation pattern and functional connectivity during visual perception of words. 61 channel recordings of electroencephalogram were obtained from 15 subjects while they were judging the meaning of Korean, English, and Chinese words with concrete meanings. We examined event-related potentials (ERP) and applied independent component analysis (ICA) to find and separate simultaneously activated neural sources. Spectral analysis was also performed to investigate the gamma-band activity (GBA, 30-50 Hz) which is known to reflect feature binding. Five significant ERP components were identified and left hemispheric dominance was observed for most sites. Meaningful differences of amplitudes and latencies among languages were observed. It seemed that familiarity with each language and orthographic characteristics affected the characteristics of ERP components. ICA helped confirm several prominent sources corresponding to some ERP components. The results of spectral and time-frequency analyses showed distinct GBAs at prefrontal, frontal, and temporal sites. The GBAs at prefrontal and temporal sites were significantly correlated with the LPC amplitude and response time. The differences in spatiotemporal patterns of GBA among languages were not prominent compared to the inter-individual differences. The gamma-band coherence revealed short-range connectivity within frontal region and long-range connectivity between frontal, posterior, and temporal sites.

• Journal of Biomedical Engineering Research
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• v.18 no.4
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• pp.365-373
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• 1997

In this paper, a new method of the 3D(dimensional) image reconstruction is proposed to build up the 3D image from 2D images using digital image processing techniques and computer graphics. First, the new feature extraction algorithm that doesn't need various input parameters and is not affected by threshold is adopted This new algorithm extracts feature points by eliminating some undesirable points on the ground of the connectivity. Second, as the cast function to reconstruct surfaces using extracted feature points, the minimum distance measure between two plane images has been adopted According to this measure, the surface formation algorithm doesn't need complex calculation and takes the form of triangle or trapezoid To investigate usefulness, this approach has been applied to a head CT image and compared with other methods. Experimental comparisons show that the suggested algorithm yields better performance on feature extraction than others. In contrast with the other methods, the complex calculation for surface formation in the proposed algorithm is not necessary.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.898-900
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• 2004

3차원 모델은 흔히 비정규(irregular connectivity) 삼각형 메쉬로 구성된다. 비정규 메쉬를 정규(completely-regular connectivity) 메쉬로 재생성라면 기하 정보를 정규적인 연결성에 상응하는 2차원 형태의 이미지로 나타낼 수 있다. 본 논문은 매개변수(parameter) 영역에서 비정규 메쉬의 특징점들로 연결된 날카로운 모서리(sharp edge)로의 특징 snapping 을 통하여 기존의 방법으로 생성된 기하 이미지보다 특징이 잘 보호된 기하 이미지 생성에 대한 방법을 제시한다. 우선 비정규 메쉬를 구성하는 정점들의 곡률을 계산한 후 매개변수 영역에서 곡률이 증가하는 방향으로 snapping을 적용하였다. 실험 결과, 본 논문에서 제시한 방법이 기존의 방법에 비해 비정규 메쉬의 특징을 보다 잘 보호할 수 있음을 확인하였다.

• Information Systems Review
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• v.5 no.2
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• pp.37-51
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• 2003

Mobile business noticed as a constructive alternative of e-commerce and e-business is being diversely considered as a new form or subset of e-business. In this study, mobile business is defined as a comprehensive alternative including e-business. The framework of the superset of e-business has two axes: connectivity and mobility. In addition, various cases based on the combination of the components are provided and explained. It is the main characteristic of this study that the element of off-line "mobility" is added to "connectivity" generally used while explaining e-commerce and e-business. For place (or location) is a prerequisite for the feature of mobility, we grope for why and how Location-Based Service (LBS) will take an important role in the development of new e-business models and services. As the real and full-scale beginning of IMT-2000 service and the rapid progress and diffusion of mobile communications services including wireless LAN require an immense and innovative way of thinking about e-commerce and e-business, the framework suggested in this study is considered to go far toward satisfying the new needs in this area.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.01a
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• pp.37-40
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• 2012

본 논문에서는 지문 인식 시스템의 인식을 위한 등록점으로 융선의 단점과 분기점에 관하여 연구하였다. 원 지문 영상은 전처리 과정을 거치게 되면서 잘못된 특징점을 포함하게 되며 이는 지문 인식 시스템의 효율성을 감소시키는 원인이 될 수 있다. 이 논문에서는 세선화된 지문 영상으로부터 후보 특징점을 추출한 후 연결성 탐색 정보를 이용하여 의사 특징점을 제거할 수 있는 알고리즘을 제안한다.

• Korean Journal of Computational Design and Engineering
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• v.1 no.3
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• pp.177-188
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• 1996

An approach to providing computational support with an expert shell is discussed with the scope of an industrial wire harness design, especially at a manufacturing stage. Key issues include the development of an architecture that supports a frequent design change among engineers associated with different parts of the wiring design process and the development of hierarchical representations that capture the different characteristics (e.g., connectivity, configuration) of the harnesses. The abstraction of design information results in features, while the abstraction of drawing elements leads to the definition of objects. These abstractions are essential for efficient transactions among people and computer tools in a domain that involves numerous interacting constraints. In this paper the strategy for the problem decomposition, the definition of features, and the ways in which features are shared by various operations and design changes, are discussed. We conclude with a discussion of some of the issues raised by the project and the steps underway to address them.

• Genomics & Informatics
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• v.3 no.1
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• pp.30-34
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• 2005

Microarray technology makes it possible to measure the expressions of tens of thousands of genes simultaneously under various experimental conditions. Identifying differentially expressed genes in each single experimental condition is one of the most common first steps in microarray gene expression data analysis. Reasonable choices of thresholds for determining differentially expressed genes are used for the next-stap-analysis with suitable statistical significances. We present a supervised model for identifying DEGs using pathway information based on the global connectivity structure. Pathway information can be regarded as a collection of biological knowledge, thus we are trying to determine the optimal threshold so that the consequential connectivity structure can be the most compatible with the existing pathway information. The significant feature of our model is that it uses established knowledge as a reference to determine the direction of analyzing microarray dataset. In the most of previous work, only intrinsic information in the miroarray is used for the identifying DEGs. We hope that our proposed method could contribute to construct biologically meaningful structure from microarray datasets.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.3
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• pp.83-94
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• 1993

Design and production of wiring for automobile systems provide the background for the development of concurrent engineering framwork. Key issues include with different parts of the wiring design process and the development of hierarchical representations that capture the different characteristics(e.g., connectivity, geometry) of the harnesses. The abstraction of design information results in features, while the abstraction of operations leads to the development of agents. These abstracts are essential for efficient transactions among people and computer tools in a domain that involves numerous interacting constraints. We have decomposed the wiring design process into four basic categories of tasks that are each addressed by an "agent" : the Environment Editor(EE), the Free Space Manager(FSM), the Wiring Editor(WE), and the Part Selector(PS). In this paper the strategy for the problem decomposition, the definition of features, and the ways in which features are used by various agents, are discussed. We conclude with a discussion of some of the issues raised by the project and the steps underway to address them.

• 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.