• Journal of Korean Neurosurgical Society
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• v.62 no.4
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• pp.405-413
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• 2019

Objective : We evaluated efficacy of combining proximal balloon guiding catheter (antegrade flow arrest) and distal access catheter (aspiration at the site of occlusion) in thrombectomy for anterior circulation ischemic stroke. Methods : We retrospectively analyzed 116 patients who underwent mechanical thrombectomy with stent retriever. The patients were divided by the techniques adopted, the combined technique (proximal balloon guiding catheter and large bore distal access catheter) group (n=57, 49.1%) and the conventional (guiding catheter with stent retriever) technique group (n=59, 50.9%). We evaluated baseline characteristics (epidemiologic data, clinical and imaging characteristics) and procedure details (the number of retrieval attempts, procedure time), as well as angiographic (thrombolysis in cerebral infarction (TICI) score, distal thrombus migration) and clinical outcome (National Institutes of Health Stroke Scale at discharge, modified Rankin Scale [mRS] at 3 months) of them. Results : The number of retrieval attempts was lower (p=0.002) and the first-pass successful reperfusion rate was higher (56.1% vs. 28.8%; p=0.003) in the combined technique group. And the rate of final result of TICI score 3 was higher (68.4% vs. 28.8%; p<0.01) and distal thrombus migration rate was also lower (15.8% vs. 40.7%; p=0.021) in the combined technique group. Early strong neurologic improvement (improvement of National Institutes of Health Stroke Scale ${\geq}11$ or National Institutes of Health Stroke Scale ${\leq}1$ at discharge) rate (57.9% vs. 36.2%; p=0.02) and favorable clinical outcome (mRS at 3 months ${\leq}2$) rate (59.6% vs. 33.9%; p=0.005) were also better in the combined technique group. Conclusion : The combined technique needs lesser attempts, decreases distal migration, increases TICI 3 reperfusion and achieves better clinical outcomes.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.367-370
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• 2003

최근 급속하게 증가하는 멀티미디어 정보를 효율적으로 다루기 위하여 멀티미디어 데이터에 대한 표현을 표준화하는 MPEG-7 표준안이 제정되었다 본 논문에서는 표준안의 Visual Descriptor 중 Edge Histogram Descriptor(EHD)에 기반한 효과적인 내용기반 이미지 검색 시스템을 설계한다. EHD의 경우 질의 이미지와 데이터베이스의 이미지 간의 유사도 연산을 통해 검색을 하는데 모든 이미지에 대해 연산을 수행하는 것은 비효율적이다. 저장된 에지 히스토그램 정보를 ‘이미지 당 빈 값’에서 ‘빈 값 당 이미지’ 정보로 매핑하는 Lookup Table를 이용하여 유사도 연산을 수행할 이미지 범위를 한정함으로써 검색 효율을 높일 수 있는 검색 방법을 제안한다.

• 한국정보통신설비학회:학술대회논문집
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• 2003.08a
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• pp.229-233
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• 2003

최근, 인터넷 사용자가 급증하면서 빠른 서비스에 대한 문제가 큰 관심이 되고있다. 특히 데이터베이스 시스템에서 저장 삭세 수정 등은 사용자에게 긴 대기시간을 요구할 수도 있기 때문에 사용자의 불평을 야기할 수 있다. 이 논문에서는 3-티어 방식에서 요즘 많이 사용되는 application server의 cache에 대해서 말하고자 한다. 기존 application server는 데이터를 application server cache에 저장하여 같은 데이터를 서비스할 경우 server의 cache를 사용하지만 이 논문에서 제안하는 것은 접속된 client를 관리하여 각각의 client에 cache를 만들고 application server나 또는 데이터베이스 server가 서비스를 하지 못할 경우는 가장 최근의 데이터를 가지고 있는 client를 찾아 client cache에 있는 데이터를 서비스 하자는 것이다.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.75.6-75
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• 2002

Current database technique offers the possibility to store giant amounts of data, worldwide networks provide the technical base for everybody to access it. However, it is usually very time-consuming or even impossible to find the most relevant information. This article describes the usage of mobile soft-ware agents to query different databases on the Internet, to rate and compress the results and to present them to the user in a consistent form, It contains a general definition of soft-ware agents, a detailed description of the approach and a discussion of its main advantages and weaknesses.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.1108-1115
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• 2003

This paper Introduces a method to automate process design using Case Based Reasoning technique. A case is represented hierarchically through functional requirement, behavioral model, and process mechanism model Specifically, a case retrieval algorithm to use function and behavior, case adaptation method to use hierarchical case representation, and a machine selection method are presented.

• Proceedings of the IEEK Conference
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• 2002.06c
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• pp.99-102
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• 2002

K-means clustering algorithm is a very popular clustering technique, which is used in the field of information retrieval. In this paper, We deal with the problem of K-means Algorithm from the view of creating the centroids and suggest a method reflecting document feature and considering the context of each document to determine the new centroids during the process of forming new centroids. For experiment, We used the automatic document summarizer to summarize the Reuter21578 newslire test dataset and achieved 20% improved results to the recall metrics.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.228-230
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• 1998

동영상 데이터가 갖는 복잡하고 다양한 관계성 때문에 기존의 키워드 기반 정보 검색 방법에는 한계가 있으면 비디오 내용에 기반해 검색을 하는 내용기반 검색기법이 요구된다. 현재 MPEG-7에서도 비디오 내용 표현 방식에 관한 국제 표준화 작업이 시작되고 있다. 본 논문에서는 영상정보와 음성정보를 사용해 비디오의 원하는 부분을 내용에 기반해 검색할 수 있는 비디오 편집 및 검색 시스템을 개발하였다.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.2
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• pp.37-45
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• 2015

The technology development of MANET and dissemination of P2P services has been made very widely. In particular, the development of many application services for the integration of P2P services in MANET has been made actively. P2P networks are commonly used because of the advantages of efficient use of network bandwidth and rapid information exchange. In P2P network, the infrastructure managing each node in the middle does not exist and each node is a structure playing a role as the sender and receiver. Such a structure is very similar to the structure of the MANET. However, it is difficult to provide reliable P2P service due to the high mobility of mobile nodes. In this paper, we propose location-based routing technique in order to provide efficient file sharing and management between nodes. GMN managing the group is elected after network is configured to the area of a certain size. Each node is assigned an identifier of 12 bit dynamically to provide routing which uses location information to the identifier. ZGT is managed in the GMN in order to provide management of group nodes and distributed cache information. The distributed cache technique is applied to provide a rapid retrieval of the sharing files in the each node. The excellent performance of the proposed technique was confirmed through experiments.

• The KIPS Transactions:PartB
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• v.11B no.4
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• pp.403-410
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• 2004

Recently, studies of image analysis, as the preprocessing stage for medical image analysis or image retrieval, are actively carried out. This paper intends to propose a way of utilizing color components for image retrieval. For image retrieval, it is based on color components, and for analysis of color, CLCM (Color Level Co-occurrence Matrix) and statistical techniques are used. CLCM proposed in this paper is to project color components on 3D space through geometric rotate transform and then, to interpret distribution that is made from the spatial relationship. CLCM is 2D histogram that is made in color model, which is created through geometric rotate transform of a color model. In order to analyze it, a statistical technique is used. Like CLCM, GLCM (Gray Level Co-occurrence Matrix)[1] and Invariant Moment [2,3] use 2D distribution chart, which use basic statistical techniques in order to interpret 2D data. However, even though GLCM and Invariant Moment are optimized in each domain, it is impossible to perfectly interpret irregular data available on the spatial coordinates. That is, GLCM and Invariant Moment use only the basic statistical techniques so reliability of the extracted features is low. In order to interpret the spatial relationship and weight of data, this study has used Principal Component Analysis [4,5] that is used in multivariate statistics. In order to increase accuracy of data, it has proposed a way to project color components on 3D space, to rotate it and then, to extract features of data from all angles.

• Journal of KIISE:Software and Applications
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• v.35 no.1
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• pp.22-32
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• 2008

To overcome the weakness of the image retrieval system using the existing Ontology and the distributed image based on the database having a simple structure, HERMES was suggested to ensure the self-control of various image suppliers and support the image retrieval based on semantic, the mentioned framework could not solve the problems which are not considered the deterioration in the capacity and scalability when many users connect to broker server simultaneously. In this paper the tables are written which in the case numerous users connect at the same time to the supply analogous level of services without the deterioration in the capacity installs Broker servers and then measures the performance time of each inner Broker Component through Monitoring System and saved and decides the ranking in saved data. As many Query performances are dispersed into several Servers User inputted from the users Interface with reference to Broker Ranking Table, Load Balancing system improving reliability in capacity is proposed. Through the experiment, the scheduling technique has proved that this schedule is faster than existing techniques.