• The Journal of Korean Association of Computer Education
• /
• v.7 no.3
• /
• pp.45-56
• /
• 2004

Java provides support for Web, concurrent programming, safety, portability, and GUI, so there is a steady increase in the number of Java users. Java is based on the object-oriented concepts such as classes, instances, encapsulation, inheritance, and polymorphism. However the JVM(Java Virtual Machine) hides most of the phenomena related to the concepts. This is why most of Java users have much difficulty in learning and using Java. As a solution to the problem, I have developed a tool Alpha that visualizes the phenomena occurred in the JVM from the standpoint of the concepts and will describe the design and features of the tool in this paper. For practicality and extendability Alpha has an MVC(Model-View-Controller) architecture and visualizes the phenomena such as object instantiations, method invocations, field accesses, cross-references among objects, and execution flows of threads in the various ways according to the levels and purposes of the users.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2015.05a
• /
• pp.515-515
• /
• 2015

토양유실량을 산정하기 위한 모델로 Universsal Soil Loss Equation(USLE)가 전 세계적으로 가장 많이 사용되고 있다. USLE 모형은 농경지에서 면상침식(Sheet erosion)과 세류침식(Rill erosion)을 모의할 수 있는 시험포단위 모형(Field-scale)으로 농경지에서 유실된 토양이 하류 하천으로 얼마나 흘러 들어가 하류 수계의 탁수발생과 이에 따른 수질악화에 얼마나 기여하는지, 즉, 유역단위의 토양유실량을 평가하는데 이용될 수 없다. 이러한 단점을 극복하기 위하여 Sediment Assessment Tool for Effective Erosion Control (SATEEC) ArcView 시스템이 개발되어 사용되고 있다. SATEEC ArcView 시스템은 USLE모형의 입력자료와 DEM만으로 유역면적에 따른 유달률을 산정하여 유역에서 유실된 토양이 얼마만큼 하류로 유달되는지를 모의할 수 있으며, 유역 경사도에 의한 유달률도 산정할 수 있어 지형적인 특성을 좀 더 다양하게 분석 할 수 있게 개발 되었다. 그러나 ArcView는 출시한지 오래되어 사용자가 많지 않고, 프로그램상의 오류가 많고, 대용량의 데이터 처리가 가능한 64비트 운영체제에서는 설치가 불가능한 단점이 있다. 또한, ArcView의 프로그래밍 언어인 Avenue는 클래스를 정의한다거나 상속을 한다거나 하는 문법을 제공하지 않기 때문에 객체지향 언어로 보기에는 부족하다고 할 수 있다. 또한, 최근의 ArcGIS 기반의 많은 모델들이 서로 연계하여 사용하고 있으나, Avenue는 기타 다른 프로그래밍 언어와 연계하여 사용하기가 쉽지 않은 단점이 있다. 그러나 최근 ArcGIS 버전들의 프로그래밍 언어인 Python은 간결하고 확장성이 좋으며, 다른 언어와의 연계가 쉽다. 또한, ArcGIS 10.x버전부터 제공되는 arcpy 모듈은 사용자와의 접근성이 매우 향상되었다. 따라서 SATEEC ArcView 버전을 ArcGIS 10.1 기반의 Python 으로 재개발하여 기존의 불편한 접근성과 대용량 데이터의 처리가 불가능했던 부분을 개선하였다.

• Journal of the Korea Society of Computer and Information
• /
• v.11 no.4 s.42
• /
• pp.87-96
• /
• 2006

Although bytecode has many good features, it has slow execution speed and it is not an ideal representation for program analysis or optimization. For analysises and optimizations. bytecode must be translated to a Static Single Assignment Form(SSA Form) But when bytecode is translated a SSA Form it has lost type informations of son variables. For resolving these problem in this paper, we create extended control flow graph on bytecode. Also we convert the control flow graph to SSA Form for static analysis. Calculation about many informations such as dominator, immediate dominator. dominance frontier. ${\phi}$-Function. renaming are required to convert to SSA Form. To obtain appropriate type for generated SSA Form, we proceed the followings. First. we construct call graph and derivation graph of classes. And the we collect information associated with each node. After finding equivalence nodes and constructing Strongly Connected Component based on the collected informations. we assign type to each node.

• Journal of KIISE:Computing Practices and Letters
• /
• v.9 no.2
• /
• pp.133-145
• /
• 2003

Web applications based on J2EE($Java^{TM}$ 2 Platform, Enterprise Edition) were occurred for solution to overcome the limitations in time and space that the former applications had. Recently, lots of solutions using frameworks are being suggested to develope applications more quickly and efficiently. In this paper, we propose the template for several processes and types, which should be taken in presentation layer of web applications. This idea was based on the fact that web applications developers can concentrate on their specific tasks with independent manner in layered architecture. This template is XML-typed document that shows information about presentation layer of Web applications, which the user wants to compose. This template is inputted to the code generator. After then, the code generator generates skeleton code in presentation layer automatically after parsing information of XML documents. It means that we can develope Web applications more efficiently, by constructing skeleton code which inherits from hot spot classes of framework. Using this template and code generator, developer can develop Web applications with little practice and also is easy to cooperate with other developers to develop them just in time with distributing the standard development process.

• Journal of Korea Spatial Information System Society
• /
• v.1 no.1 s.1
• /
• pp.5-18
• /
• 1999

Recently, the necessity of automatic knowledge extraction from spatial data stored in spatial databases has been increased. Spatial data mining can be defined as the extraction of implicit knowledge, spatial relationships, or other knowledge not explicitly stored in spatial databases. In order to extract useful knowledge from spatial data, an object management system that can store spatial data efficiently, provide very fast indexing & searching mechanisms, and support a distributed computing environment is needed. In this paper, we designed and implemented an open object management system for spatial data mining, that supports efficient management of spatial, aspatial, and knowledge data. In order to develop this system, we used Open OODB that is a widely used object management system. However, the lark of facilities for spatial data mining in Open OODB, we extended it to support spatial data type, dynamic class generation, object-oriented inheritance, spatial index, spatial operations, etc. In addition, for further increasement of interoperability with other spatial database management systems or data mining systems, we adopted international standards such as ODMG 2.0 for data modeling, SDTS(Spatial Data Transfer Standard) for modeling and exchanging spatial data, and OpenGIS Simple Features Specification for CORBA for connecting clients and servers efficiently.