Yoonsun Lim

An e-learning framework supporting personalization and collaboration

Advances in Internet technology have made possible, rapid adoption of e-learning in many fields of society. Various educational methods for e-learning have been developed because personalization can be easily implemented through web services. However, these e-learning methods are not widely used because it is difficult for instructors to apply them in developing their courseware. Currently, the most widely used style of e-learning courseware is viewing video clips of lectures and discussing the lecture using bulletin boards. It is an electronic version of the traditional classroom. In this paper, we propose a user-friendly e-learning framework that supports personalization and collaboration between the instructor and the students. Instructors can create various levels of learning objects and define the relationships between the objects. Students can select the topics of their interest and dynamically adjust the level of learning in real time. Multiple instructors can cooperate in expanding the courseware. All the participants can also annotate the learning materials independently.

An Enterprise Security Management System as an ASP Solution

Advances in Internet technologies have enabled not only large corporations but also small/medium businesses to utilize the Internet for their businesses. While enterprises can be more competitive with such high-tech tools, they are now inevitably exposed to various security risks and threats. In order to protect their information assets, large corporations purchase and operate enterprise security management systems which provide enterprise-level integrated security. However, they are so expensive that small/medium businesses can hardly afford to utilize one. We hold that one way of providing integrated security to small/medium businesses in a costeffective manner is by means of an ASP solution. In this paper, we justify our proposition by analyzing the market trends for ASP in conjunction with security management software. We also propose a web-based security management system that can be used as an ASP solution. To the best of our knowledge, it is the first such system and is currently running as a commercial solution at a Korean ASP which provides services to 3,000 small/medium businesses.

A Bitmap Index for Multidimensional Data Cubes

Multidimensional arrays can be used to store multidimensional data cubes. One way of storing such array onto disk is to partition the array into a set of small chunks that can fit in a disk block. Chunks are usually of the same side length and are compressed before being stored, in order to achieve high query processing speed and space utilization. This scheme is called the chunk-based cube storage scheme. Although the scheme is considered to be a position based storage scheme, the chunks cannot be retrieved fast without using indexes since they are compressed. In this paper, we propose a bitmap index for such a storage scheme. The index can be constructed with the data cube in parallel. The relative positions of the chunk retrieval can be done in constant time. We placed in an index block as many chunks as possible so that the number of index searches is minimized for OLAP operations such as slice, dice, and range queries. We evaluated the proposed index by comparing it with existing multidimensional indexes such as UB-tree and grid file in terms of time and space.

A Reuse-Based Software Development Method

One of the primary obstacles to the reuse of independently-developed binary components on the industrial level lies in that the existing component technologies do not clearly separate component assembly from component development. To tackle this problem, we propose a new component model, a component assembly method, and a runtime framework, which together amounts to what we call Active Binding Technology. This new component model suggests how to make software components as pure parts, and the assembly method expresses message flows between these components in a model, while the runtime framework performs dependency injection to make the components interact with each other observing type safety constraints.

Active Binding Technology: A Reuse-Enabling Component Model

One of the primary obstacles to the reuse of independently-developed binary components on the industrial level lies in that the existing component technologies do not clearly separate component assembly from component development for type safety. To tackle this problem with type safety intact, we propose a new component model, Active Binding Technology, in which each Active Binding component, unlike the conventional one that actually has provided interfaces only, contains independently-defined required interfaces as well. The assembler can later adjust any interface mismatches between pre-produced Active Binding components in the glue component, whose template code is generated from the metadata of the components being combined.

An enterprise security management system as a web-based application service for small/medium businesses

Enterprises use security equipments in order to protect their information assets from various attacks such as viruses and hacking. However, such individual equipments hardly provide enterprise level integrated security. Recently, there has been a great need in small/medium businesses to purchase such integrated security services in a cost effective way by means of an ASP solution. We propose the architecture of a web-based enterprise security manager that can be used as an ASP solution. To the best of our knowledge, it is the first such system that provides integrated security management services through the web. We conducted experiments on our prototype system, and showed that it could handle 30 million logs per day, and serve 300 concurrent web users with 20 transactions per session. This system is now running as a commercial application service at KT Bizmeka, which is one of the largest Korean ASPs.