• The Journal of Korean Association of Computer Education
• /
• v.4 no.1
• /
• pp.175-181
• /
• 2001

WBI provides new opportunities to realize the flexible learning environment based on hypermedia and to support distance learning with a diverse interaction. The instructors or learners in WBI claim to be able to resolve reluctant fluctuations such as disorientation and cognitive overload. To overcome these phenomena, a supplementary tool able to manage a learning space organized by the instructor's or learner's own way and offer effective navigation techniques is presented in this paper. A learning space management and navigation tool called HyperMap dynamically represents the learning space in the form of a two-dimensional labeled graph. This HyperMap also can be used for an instruction design tool, learners portfolio for the exchange of learning experiences, and the assessment of WBI.

• The KIPS Transactions:PartD
• /
• v.12D no.4 s.100
• /
• pp.569-582
• /
• 2005

As information and business communication via Internet are growing up, web-based software is wide spread and more important on the viewpoint of software qualify than stand-alone. Research on verification of web content links and web-based Program was tried, but has short on covering various types of web based software and making experiments to be applied in real testing practice. This paper suggests a modeling technique to be applied to dynamic and various types of web-based software. First, it identifies each elements consisting of web-based software and then construct a model of Object Control Flow Graph and Object Relationship Diagram. We can generate test cases covering all test paths of ORD or invoking key points test route. Suggested modeling method and test case selection technique are verified by applying five types of web-based software and compared with other web-based test techniques.

• Journal of KIISE:Computer Systems and Theory
• /
• v.30 no.12
• /
• pp.699-707
• /
• 2003

RBAC is accepted as a more advanced control method than existing DAC and MAC. Studies on the permission-role part of RBAC model are relatively insufficient compared with those on the user-role part, and researches on symmetric RBAC models to overcome this is also in an incipient stage. Therefore there is much difficulty in assigning permissions suitable for roles. This paper proposes an symmetric RBAC model that supplements the constraints on permission assignment set forth by previous studies. The proposed symmetric RBAC model reflects the conflicts of interests between roles and the sharing and integration of permissions on the assignment of permissions by presenting the constraints on permission assignment that take the separation of duties and role hierarchies into consideration. In addition, by expressing constraints prescribing prerequisite relations between dynamic permissions through AND/OR graphs, it is possible to effectively limit the complicated prerequisite relations of permissions. The constraints on permission assignment for the proposed symmetric RBAC model reduce errors in permission assignment by properly detailing rules to observe at the time of permission assignment.

• Journal of KIISE:Software and Applications
• /
• v.30 no.1_2
• /
• pp.73-80
• /
• 2003

The Java programming language is designed for developing effective applications in a heterogeneous network environment. Major problem in Java is its performance. many attractive features of Java make the development of software easy, but also make it expensive to support ; applications written in Java are often much slower than their counterparts written in C or C++. To use Java`s attractive features without the performance penalty, sophisticated optimizations and runtime systems are required. Optimising Java bytecode has several advantages. First, the bytecode is independent of any compiler that is used to generate it. Second, the bytecode optimization can be performed as a pre=pass to Just-In-Time(JIT) compilation. Many attractive features of Java make the development of software easy, but also make it expensive to support. The goal of this work is to develop automatic construction of code optimizer for Java bytecode. We`ve designed and implemented a Bytecode Optimizer that performs the peephole optimization, bytecode-specific optimization, and method-inlining techniques. Using the Classfile optimizer, we see up to 9% improvement in speed and about 20% size reduction in Java class files, when compared to average code using the interpreter alone.

• Journal of the Korean Data and Information Science Society
• /
• v.10 no.2
• /
• pp.501-510
• /
• 1999

We have seen a rapid development of multimedia intustry as computer evolves and the internet has changed our way of life dramatically in these days. There we several attempts to teach elementary statistics on the web but most of them are based on commercial products. The need for statistical data analysis and decision making based on those analysis is growing. In this article we try to show one way of reaching that goal by using a server side scripting language PHP3 toghether with extra graphical module and statistical distribution module on the web. We showed some elementary exploratory graphical data analysis and statistical inferences. There are plenty of room of improvements to make it a full blown statistical analysis tool on the web in the new future. All the programs and databases used in our article we public programs. The main engine PHP3 is included as an apache web server module so it is very light and fast. It will be much better when the PHP4(ZEND) will be officially out in terms of processing speed.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.3
• /
• pp.458-470
• /
• 2018

As the requirements of web apps become complex and rapidly changing, the maintenance of web apps becomes more important. However, web apps have a problem that more often than not there is not enough documentation to understand and maintain them. Thus, their effective maintenance requires models that represent their internal behavior occurring when they dynamically generate web pages. Previous works identify web components (such as JSPs and Servlets) as participants in the behavior but not web resources (such as images, CSS files, and JavaScript files). Moreover, they do not identify dependency relations between web components and web resources. This paper dynamically analyzes Java web apps to extract such dependency relations, which are included in our graph model for page generation. Case studies using open-source web apps show the applicability of the proposed approach.

• Communications of Mathematical Education
• /
• v.35 no.3
• /
• pp.323-340
• /
• 2021

The purpose of this case study is to explore the similarities revealed in the process of solving and generalizing word problems related to systems of linear equations in two variables according to covariational reasoning. As a result, student S, who reasoned with coordination of value level, had a static image of the quantities given in the situation. student D, who reasoned with smooth continuous covariation level, had a dynamic image of the quantities in the problem situation and constructed an invariant relationship between the quantities. The results of this study suggest that the activity that constructs the relationship between the quantities in solving word problems helps to strengthen the mathematical problem solving ability, and that teaching methods should be prepared to strengthen students' covariational reasoning in algebra learning.

• Convergence Security Journal
• /
• v.21 no.2
• /
• pp.47-56
• /
• 2021

Network topology visualization has been studied a lot since the past and developed with many tools. The network topology has strength in understanding the overall structure of a network physically and is useful for understanding data flow between nodes logically. Although there are existing tools, not many can be utilized efficiently while using the general network node data structure and express the topology similar to the actual network structure. In this paper, we propose an efficient method to visualize topology using only connection information of network nodes. The method finds the central node by using the centrality, the influence of nodes in the network, and visualizes the topology by dynamically segmenting all nodes and placing network nodes in 3D space using the weight of the child node. It is a straightforward method, yet it effectively visualizes in the form of an actual network structure.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.30 no.6
• /
• pp.1079-1085
• /
• 2020

Fuzzing is used to find vulnerabilities for a library. Because library fuzzing only tests the implemented functions, in order to achieve higher code coverage, additional functions that are not implemented should be implemented. However, if a function is added without regard to the calling relationship of the functions in the library, a problem may arise that the function that has already been tested is added. We propose a novel method to improve the code coverage of library fuzzing. First, we analyze the function call graph of the library to efficiently add the functions for library fuzzing, and additionally implement a library function that has not been implemented. Then, we apply a hybrid fuzzing to explore for branches with complex constraints. As a result of our experiment, we observe that the proposed method is effective in terms of increasing code coverage on OpenSSL, mbedTLS, and Crypto++.

• Journal of radiological science and technology
• /
• v.29 no.4
• /
• pp.249-255
• /
• 2006

Purpose: The diagnostic utility of fluorine-18 2-deoxy-D-glucose positron emission tomograhpy ($^{18}F-FDG $PET) for the non-invasive differentiation of focal lung lesions originated from cancer or inflammation disease by combined visual image interpretation and semi-quantitative uptake value analysis has been documented. In general, Standardized Uptake Value(SUV) is used to diagnose lung disease. But SUV does not contain dynamic information of lung tissue for the glucose. Therefore, this study was undertaken to hypothesis that analysis of dynamic kinetics of focal lung lesions base on $^{18}F-FDG$ PET may more accurately determine the lung disease. So we compared Time Activity Curve(TAC), Standardized Uptake Value-Dynamic Curve(SUV-DC) graph pattern with Glucose Metabolic Rate(MRGlu) from Patlak analysis. Methods: With lung disease, 17 patients were examined. They were injected with $^{18}F-FDG$ over 30-s into peripheral vein while acquisition of the serial transaxial tomographic images were started. For acquisition protocol, we used twelve 10-s, four 30-s, sixteen 60-s, five 300-s and one 900-s frame for 60 mins. Its images were analyzed by visual interpretation TAC, SUV-DC and a kinetic analysis(Patlak analysis). The latter was based on region of interest(ROIs) which were drawn with the lung disease shape. Each optimized patterns were compared with itself. Results: In TAC patterns, it hard to observe cancer type with inflammation disease in early pool blood area but over the time cancer type slope more remarkably increased than inflammation disease. SUV-DC was similar to TAC pattern. In the result of Patlak analysis, In time activity curve of aorta, even though inflammation disease showed higher blood activity than cancer, at first as time went by, blood activity of inflammation disease became the lowest. However, in time activity curve of tissue, cancer had the highest uptake and inflammation disease was in the middle. Conclusion: Through the examination, TAC and SUV-DC could approached the results that lung cancer type and inflammation disease type has it's own difference shape patterns. Also, it has outstanding differentiation between cancer type and inflammation in Patlak and MRGlu analysis. Through these analysis methods, it will helpful to separation lung disease.