• The KIPS Transactions:PartC
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• v.13C no.1 s.104
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• pp.19-26
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• 2006

Recently, web server hacking is trending toward web application hacking which uses comparatively vulnerable web applications based on open sources. And, it is possible to hack databases using web interfaces because web servers are usually connected databases. Web application attacks use vulnerabilities not in web server itself, but in web application structure, logical error and code error. It is difficult to defend web applications from various attacks by only using pattern matching detection method and code modification. In this paper, we propose a method to secure the web applications based on profiling which can detect and filter out abnormal web application requests.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.431-437
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• 2003

In this paper, an approximate optimization program based on GUI(graphic user interface) environment is developed. This program is coded by using Fortran and Visual basic. Fortran is used to Progress approximate optimization process. Visual basic is used to make user environment for user to use conveniently. Inside of this program, it uses two independent programs. One is commercial program, ANSYS, and the other is optimization program, PLBA(Pshenichny-Lim-Belegundu Arora). The former is used to obtain approximate equation of stress and displacement of a structure. The latter is used to solve approximate optimization. This algorithm uses second-order information of a function and active set strategy. This program is connecting ANSYS and PLBA. And it progress the process repeatedly until it obtain optimum value. As a method of approximate optimization, sequential design domain(SDD) is introduced. SDD starts with a certain range which is offseted from midpoint of an initial design domain and then SDD of the next step is determined by optimal point of a prior step.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.3
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• pp.253-263
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• 2008

Extension of IFC data model for steel bridge members is proposed to represent detailed design information. First of all, the design data items and their representation method are classified by analyzing primary references such as design specification, structural calculation documents and shop drawings. Some of the classified items are enough to be represented by the existing IFC model. However, the need of additional model is noted to systematically represent the design information for other items such as stiffener, diaphragm, joint system, and shear connector. An inheritance relations and properties for added model are also defined. The application program based on the proposed data model is developed. In the end, by loading the application program on the AutoCAD 2002 program, end-users can input the design information of steel bridge members. The applicability and efficiency of the proposed data model and the program are verified by checking the section area, intervals, and interferences.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1128-1131
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• 2005

The document transformation system is more widely used in order to transform business documents efficiently in diverse organization. In established researches on document transformation systems have been carried mainly focused on XML however, it is not only transformed XML form but also EDI or local form in realistic import and export process. Particularly, in the most completed research relate on document transformation, they used ontology to get rid of non-efficiency in the connection of XML schema by manual. Hence, those researches are lack of features, which are construct and modify the domain ontology automatically and the size wasn't enough to realize itself. In this paper we study development of ontology and basic system, which is critical in intelligent document conversion system. And we develop an ontology with editor can be modified and complemented by users, as well as we make it used in real import and export business process.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.151-160
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• 2005

The exponential growth of Web users requires the web serves with high expandability and reliability. It leads to the excessive transmission traffic and system overload problems. To solve these problems, cluster systems are widely studied. In conventional cluster systems, when the request size is large owing to such types as multimedia and CGI, the particular server load and response time tend to increase even if the overall loads are distributed evenly. In this paper, a cluster system is proposed where each Web server in the system has different contents and loads are distributed efficiently using the Web server resource information such as CPU, memory and disk utilization. Web servers having different contents are mutually connected and managed with a network file system to maintain information consistency required to support resource information updates, deletions, and additions. Load unbalance among contents group owing to distribution of contents can be alleviated by reassignment of Web servers. Using a simulation method, we showed that our method shows up to $50\%$ about average throughput and processing time improvement comparing to systems using each LC method and RR method.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.3
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• pp.293-301
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• 2011

This paper proposes a bridgeless half-bridge AC-DC converter with high-efficiency. The proposed converter integrates the bridgeless power factor correction (PFC) circuit with the asymmetrical pulse-width modulated (APWM) half-bridge DC-DC converter. It provides the isolated DC output voltage from the AC line voltage without using any full-bridge diode rectifier. Conduction losses are lowered with a simple circuit structure. Switching losses are also reduced by achieving zero-voltage switching (ZVS) of the power switches. By using series-connected two transformers, the proposed converter provides a low-profile and high power density for AC-DC converters. The performance of the proposed converter is verified from a 250 W (48 V / 5.2 A) experimental prototype circuit at $90 \;V_{rms}$ line voltage.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2005.11a
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• pp.453-460
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• 2005

P2P(Peer to Peer) 기술은 잠재적 능력에도 불구하고 컨텐츠의 저작권문제와 보안문제 등으로 인하여 많은 사람들이 충분히 활용하지 못하고 있다. 본 연구는 인터넷 사용자(개인)와 소규모 서버를 운영하는 조직들이 정보 제공, 분배, 공유의 정보시스템 구조를 자신들의 목적에 맞게 자유롭게 만들 수 있는 프레임워크인 오픈웨어 (Openware)의 개발에 관한 것이다. 오픈웨어는 P2P기반 시스템으로 다음과 같은 특징올 갖는다. 1) 다수의 서버와 클라이언트로 이루어지는 구조로, 사용자의 목적에 맞게 집중형 혹은 분산형 구조를 자유롭게 혼합하여 정보시스템을 구성 할 수 있다. 이러한 정보 구조의 유연성은 다양한 형태의 협업(개인과 개인, 개인과 그룹, 그룹과 그룹)이 요구되는 응용 시스템의 기반을 제공한다. 2) 데이터 관점에서 오픈웨어는 개인이 데이터베이스를 손쉽게 생성, 관리 할 수 있고, 자신의, 데이터 혹은 데이터베이스 구조를 다른 사람이나 그룹과 공유 하거나 통합 할 수 있다. 3) 데이터 통신면에서 오픈웨어는 HTTP(HyperText Transfer Protocol) 프로토콜만을 사용하는 웹 기반 시스템으로 인터넷에 연결 되어있는 누구와도 오픈웨어를 통해 협업이 가능하다. 4) 소프트웨어 이름에서 알 수 있듯이 오픈웨어는 Java, JSP, Apache, Resin등 공개소프트어로 만들어져 있고, 오픈웨어 자체도 공개소프트웨어이다. 오픈웨어는 개인과 그룹의 흠페이지 생성과 관리, 파일 공유 기능이 구현 되어있고, 데이터베이스 공유, 통합 기능을 이용하여 개인이나 그룹의 주소록관리, 일정관리 등이 가능하다. 오픈웨어는 사용자 흑은 개발자가 다양한 형태의 응용컴포넌트를 자유롭게 등록하여 기능을 추가 할 수 있는 확장성올 제공하고 있어서, 앞으로 e-메일, 매신저, 전자결재, 지식관리시스템, 인터넷 방송 시스템의 기반 구조 역할을 할 수 있다. 현재 오픈웨어에 적용하기 위한 P2P 기반의 지능형 BPM(Business Process Management)에 관한 연구와 X인터넷 기술을 이용한 RIA (Rich Internet Application) 기반 웹인터페이스 연구를 진행하고 있다.

• The KIPS Transactions:PartD
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• v.9D no.3
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• pp.447-456
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• 2002

Web applications haute different structural characteristics from conventional applications. A web application typically consists of server-side script elements which run on web sowers, client-side script elements which run on the client web-browser, link elements that the user clicks, and event elements that connect user-triggered request to the client script elements. These four elements are combined to form a web application. In such environments, direct application of conventional methods for measuring application complexity may not be possible, because they are primarily designed to measure complexity of modules and classes. In this paper, therefore, we propose metrics of Cyclomatic Complexity for Web Application (CCWA). We developed a tool to measure such metrics and applied it to the real-world examples. We found that the proposed CCWA metrics can be used for measuring complexity of highly complex web applications, which is not possible with conventional module and class based measurement techniques.

• Journal of Intelligence and Information Systems
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• v.11 no.2
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• pp.17-29
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• 2005

The purpose of the study was to explore the potential of the Social Network Analysis as an analytical tool for scientific investigation of learner-learner, or learner-tutor interaction within a Computer Supported Corporative Learning (CSCL) environment. Theoretical and methodological implication of the Social Network Analysis had been discussed. Following theoretical analysis, an exploratory empirical study was conducted to test statistical correlation between traditional performance measures such as achievement and team contribution index, and the centrality measure, one of the many quantitative measures the Social Network Analysis provides. Results indicate the centrality measure was correlated with the higher order teaming performance and the peer-evaluated contribution indices. An interpretation of the results and their implication to instructional design theory and practices were provided along with some suggestions for future research.

• Journal of Korea Multimedia Society
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• v.10 no.5
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• pp.594-603
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• 2007

This paper proposes a watermarking scheme for 3D CAD design drawing. In the proposed scheme, we embed binary watermarks into line, arc, and polygon face components that are the basic component of 3D CAD design drawing. The embedding target component can be selected randomly among three components or by the component distribution in drawing. In line components, a watermark bit is embedded into the ratio of the length of a target line and an average length of lines that are connected into a target line. Furthermore, a watermark bit is embedded into a curvature radius on the basis of a center point in a arc component and also is embedded into a ratio of two sides in a polygonal face component. Experimental results verified that the proposed watermarking has the robustness against Format conversion, rotation translation, scaling, cropping, and layer cutting and also SNR of watermarked component is about 39.89-42.50 dB.