• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.274-281
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• 2006

Sensor network applications need synchronized time extremely such as object tracking, consistent state updates, duplicate detection, and temporal order delivery. This paper describes reliable time synchronization protocol (RTSP) for wireless sensor networks. In the proposed method, synchronization error is decreased by creating hierarchical tree with lower depth and reliability is improved by maintaining and updating information of candidate parent nodes. The RTSP reduces recovery time and communication overheads comparing to TPSN when there are topology changes owing to moving of nodes, running out of energy and physical crashes. Simulation results show that RTSP has about 20% better performance than TPSN in synchronization accuracy. And the number of message in the RTSP is $20%{\sim}60%$ lower than that in the TPSN when nodes are failed in the network. In case of different transmission range of nodes, the communication overhead in the RTSP is reduced up to 40% than that in the TPSN at the maximum.

• Journal of KIISE:Software and Applications
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• v.31 no.7
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• pp.911-921
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• 2004

Accurate minutiae extraction from input fingerprint images is one of the critical modules in robust automatic fingerprint identification system. However, the performance of a minutiae extraction is heavily dependent on the quality of the input fingerprint images. If the preprocessing is performed according to the fingerprint image characteristics in the image enhancement step, the system performance will be more robust. In this paper, we propose a knowledge-based preprocessing method, which extracts S features (the mean and variance of gray values, block directional difference, orientation change level, and ridge-valley thickness ratio) from the fingerprint images and analyzes image quality with Ward's clustering algorithm, and enhances the images with respect to oily/neutral/dry characteristics. Experimental results using NIST DB 4 and Inha University DB show that clustering algorithm distinguishes the image Quality characteristics well. In addition, the performance of the proposed method is assessed using quality index and block directional difference. The results indicate that the proposed method improves both the quality index and block directional difference.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.275-284
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• 2009

Fast development of network technology and digitalization of various kinds of information are accelerating the convergence of between them. Accordingly, an environment for integrated service is needed, where users can be provided with various kinds of information such as voice, video, and text, using even different kinds of devices in heterogeneous networks for communication and broadcasting. In general, enablers integrate several functions to provide with various services in application layer based on IMS in BcN including even different kinds of networks. But in order to receiving convergence services, we must reason the environment of the user through the profiles of the networks and the devices and provide a suitable service to the user. In this paper, we will propose an efficient architecture and functions of a context-aware module which decides the appropriate services based on the profiles in the IMS enabler and its convergence service environments.

• Journal of the Korean association of regional geographers
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• v.21 no.1
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• pp.21-38
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• 2015

This study attempts to estimate the complementarity between 21 cities in the Korean Southeastern Region using data on the network time distance and the volume of flow between the cities. Four types of flows recognized are people, commodities, information and finance. The first two types of flows are thought to be made on the transportation network while the last two are on the communication network. For the purpose of the study, the expected volumes of flows between cities are first estimated using the gravity-based regression and doubly-constrained entropy maximization models. These baseline volumes are then subtracted from the observed volumes of flows (of people and commodities) or the estimated volumes of flows (of information and finance) in order to identify positive differences or complementarities. The result shows that these four types of complementarity flows form distinctive urban networks in terms of spatial pattern and urban hierarchy. This suggests that more customized strategies to different types of complementarity are recommended to properly address the issues related to network infrastructure provision in the pursuit of the network city model in the region.

• Journal of the Korean association of regional geographers
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• v.20 no.2
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• pp.217-229
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• 2014

This study was performed to identify neighborhood deprivation indicators associated with health and to test the contextual effects of those indicators on individual health. This study calculated SMR based on Dong district and see the differences of prediction across deprivation index and indicators. Then, a multi-level analysis using HGLM was conducted to test the contextual effect of neighborhood depreivation indicators on health after controlling for demographic and socioeconomic status of individuals. The results showed that regional SMR had strong correlations with land price, education, welfare recipients, female household proportion in Dong district but failed to show the correlation with individual health and neighborhood deprivation. Individual health was only associated with individual level of demographic and socioeconomic status. That is, spatial dispersion of illness is understood as the distribution of social classes in terms of socioeconomic status of individuals, not the contextual aspects of community.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.725-731
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• 2008

In this paper, we propose a novel construction scheme for the personalized e-Learning system based on IRT(item response theory), which can be applied to the content including non-hierarchical and horizontal learning objects in its learning nodes. Especially the proposed system performs tests and re-estimates examinee ability during the learning nodes are operating so that the results are directly applied to the next node. This scheme can be called a dynamic relationship between test and learning which is totally different from conventional customization based on learning procedures separated from test steps. Moreover, we should periodically modify the averages of node difficulties, item parameters, and ability parameters of students so that the system have more accurate personalized learning capability. As a result, this scheme maximizes learning efficiency offering the most appropriate learning objects and items to the individual students according to their estimated abilities and the system itself should obtain continuous improvements by modifying the parameters and fulfilling periodical feedbacks.

• Journal of Korea Technology Innovation Society
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• v.12 no.1
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• pp.113-136
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• 2009

The purpose of this study is to develop meta evaluating indicators for Defense R&D Programs in Korea. At first, the four components of this meta evaluation model were designed, which are evaluation context, evaluation input, evaluation process, evaluation output. And fifty two indicators were developed for this meta evaluation. Basic model of meta evaluation was derived from the literature review and brain storming. And this meta evaluation model was determined by adapting the result of experts who performed evaluations for Defense R&D Programs in recent years. Factor Analysis method was used to verify the validity of meta evaluation model. The survey of fifty three members turned out that Cronbach' ${\alpha}$ was over 0.6 in evaluation components and items. And the reliability of evaluation context was 0.877, that of evaluation input was 0.755, that of evaluation process was 0.755, that of evaluation output was 0.755 respectively. Analytic Hierarchy Process (AHP) method was used in assigning the evaluation weight. The survey of twenty two members showed that the Consistency Ratio was 0.09 in evaluation components and items.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.1
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• pp.167-177
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• 2018

As the number of attacks on vehicles has increased, studies on CAN-based security technologies are actively being carried out. However, since the upper layer protocol of CAN differs for each vehicle manufacturer and model, there is a great difficulty in researches such as developing anomaly detection for CAN or finding vulnerabilities of ECUs. In this paper, we propose a method to infer the detailed structure of the data field of CAN frame by analyzing CAN trace to mitigate this problem. In the existing Internet environment, many researches for reverse engineering proprietary protocols have already been carried out. However, CAN bus has a structure difficult to apply the existing protocol reverse engineering technology as it is. In this paper, we propose new field classification methods with low computation-cost based on the characteristics of data in CAN frame and existing field classification method. The proposed methods are verified through implementation that analyze CAN traces generated by simulations of CAN communication and actual vehicles. They show higher accuracy of field classification with lower computational cost compared to the existing method.

• Journal of KIISE:Software and Applications
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• v.31 no.2
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• pp.203-212
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• 2004

The watermarking is a method to achieve the copyright protection of multimedia contents. Among several media, the left documents show very peculiar properties: block/line/word patterning, clear separation between foreground and background areas. So algorithms specific to the text documents are required that meet those properties. This paper proposes a novel watermarking algorithm for the grayscale text document images. The algorithm inserts the watermark signals through the edge direction histograms. A concept of sub-image consistency is developed that the sub-images have similar shapes in terms of edge direction histograms. Using Korean, Chinese, and English document images, the concept is evaluated and proven to be valid over a wide range of document images. To insert watermark signals, the edge direction histogram is modified slightly. The experiments were performed on various document images and the algorithm was evaluated in terms of imperceptibility and robustness.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.247-249
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• 2004

마이크로어레이 기술은 근래에 개발된 신기술로써 동시에 수천-수만 개의 유전자 발현을 측정할 수 있어 다양한 생물학적 연구에 이용되고 있다. 여러 단계의 실험 과정과 이를 통해 얻은 다량의 데이터를 처리하기 위해서는 이를 효율적으로 관리. 저장, 분석할 수 있는 통할 정보 관리 시스템을 필요로 한다. 현재 외국에서는 몇몇 관리시스템이 개발되어 있고. 국내에서도 WEMA 등이 있지만 아직 데이터 관리부분에 기능이 치우쳐 있다. 따라서 우리는 복잡한 자료구조를 가지는 마이크로어레이의 실험 정보와 각 단계별 처리 정보 등을 사용자의 관점에서 효과적이고 체계적으로 관리할 수 있고, 데이터 정규화 및 다양한 통계적 분석 기능을 갖춰 불필요한 시간과 비용을 줄임으로써 마이크로어레이 연구에 도움을 주고자 통합 분석관리 시스템 cMAMS (cDNA Microarray Analysis and Management System)를 개발하였다. 웹 기반으로 구현된 cMAMS는 데이터를 저장, 관리하는 부분과 데이터를 분석하는 부분, 그리고 모든 관련 점보가 저장되는 데이터베이스 부분으로 구성되어 있다 데이터관리부분에서는 WEMA의 계층적 데이터구조론 도입해 관리의 효율성을 높이고 시스템의 이용자를 시스템운영자, 프로젝트관리자, 일반사용자로 구분하여 데이터 접근을 제한함으로써 보안성을 높였다. 통계처리 언어 R로 구현된 데이터분석 부분은 7 단계의 다양한 분석(전처리 정규화, 가시화, 군집분석. 판별분석, 특이적 발현 유전자 선뿐, 마이크로어레이 간의 상판분석)이 가능하도록 구현하였고, 분석결과는 데이터베이스에 저장되어 추후에 검토 및 연구자간의 공유가 가능하도록 하였다. 데이터베이스는 실험정보가 저장된 데이터베이스, 분석결과가 저장된 데이터베이스, 그리고 유전자 정보 탐색을 위한 데이터베이스로 분류해 데이터를 효율적으로 관리할 수 있게 하였다. 본 시스템은 LiNUX를 운영체계로 하고 데이터베이스는 MYSQL로 하여 JSP, Perl. 통계처리 언어인 R로 구현되었다.