• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.2
• /
• pp.120-128
• /
• 2003

When considering the use of rapid prototyping (RP), there are many issues a designer has to address for handling an STL model, the de facto standard fur RP. Today designers can skip all these issues by visiting web-based service bureaus that readily supply needed information for the RP services. Since orders are taken for RP parts through the web page of service providers designers are now asked to upload their STL files to the company server either by direct upload, ftp file transfer, or as an e-mail attachment. If the service bureau, however, fixes or edits an STL filceto optimize the RP process but neglects to tell its customer about the rework in detail, it may cause problems down the line in processing of the original CAD data for other applications. In this paper, we propose a framework for a collaborative virtual environment between CAD designers and RP processes on the internet which directly provides designers with an advanced preprocessor functionality, design visualization, as well as model display, repair, and slicing over the network. This can help smooth data transfer from CAD to RP process with minimum inconsistency in CAD.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.10a
• /
• pp.522-525
• /
• 2006

그리드 기반 분산객체지향 가상환경 시스템인 DOVE-G는 많은 리소스를 요구로 하는 분산된 그리드 컴퓨팅 어플리케이션에서 효율적인 병렬프로그래밍 환경을 지원하는데 이에 웹서비스를 이용해 다양한 어플리케이션에서 고급 그리드 컴퓨팅 환경을 제공할 수 있다. 본 논문에서는 웹서비스를 이용해 DOVE-G의 implementation을 모르더라도 DOVE-G 서비스를 쉽게 이용할 수 있도록 해주는 Interface Object와 Agent Object 두 개의 DOVE-G Object를 이용한 통신기법을 제시한다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2013.05a
• /
• pp.144-147
• /
• 2013

클라우드 컴퓨팅은 낭비되는 컴퓨팅 자원들을 클라우드 서버를 통해 처리 가능한 고사양의 컴퓨팅 환경을 제공한다. 클라우드 컴퓨팅은 노드에 가상머신을 할당하여 사용자의 요구를 처리하는데, 노드의 공정한 사용과 사용자 요구사항 충족을 위해 FCFS, 라운드 로빈 등의 가상머신 할당 기법을 사용한다. 본 논문에서는 노드의 효율적인 사용을 위해 클라우드 서버에서 관리 중인 노드들의 성능을 미리 분석하고 가상머신을 할당 혹은 재할당시 분석된 결과를 바탕으로 할당할 노드를 선택하고 관리하는 시스템을 제안한다. 노드의 성능을 미리 분석함으로서 할당을 위한 가상머신 선택을 위한 연산을 줄여 신속하고 효율적인 가상머신 할당이 가능하다.

• Educational Technology International
• /
• v.20 no.2
• /
• pp.137-168
• /
• 2019

This study examined the effects of information volume and distribution on learners' cognitive load and recall in a mobile augmented reality (AR) environment. Information volume refers to the degree of information users are provided in a learning task, while information distribution indicates the way in which information is distributed, either in a virtual or real format. Sixteen undergraduate students participated in the study, which employed a 2 × 3 randomized block factorial design with repeated measures. Information volume and distribution were independent variables, and factors in learners' cognitive load (mental effort, perceived ease of use, and perceived task difficulty) and recall test scores were the dependent variables. Information volume had significant main effects on perceived ease of use and task difficulty, and recall test scores, while information distribution had significant main effects on perceived task difficulty and test scores. A detailed discussion and implications are provided.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.3
• /
• pp.259-268
• /
• 2019

Even if only two ships are encountered, a collision may occur due to the mistaken judgment of the positional relationship. In other words, if an officer does not know a target ship's intention, there is always a risk of collision. In this paper, the experiments are conducted to investigate how the intention affects the action of collision avoidance in cooperative and non-cooperative situations. In non-cooperative situation, each ship chooses a course that minimizes costs based on the current situation. That is, it always performs a selfish selection. In a cooperative situation, the information is exchanged with a target ship and a course is selected based on this information. Each ship uses the Distributed Stochastic Search Algorithm so that a next-intended course can be selected by a certain probability and determines the course. In the experimental method, four virtual ships are set up to analyze the action of collision avoidance. Then, using the actual AIS data of eight ships in the strait of Dover, I compared and analyzed the action of collision avoidance in cooperative and non-cooperative situations. As a result of the experiment, the ships showed smooth trajectories in the cooperative situation, but the ship in the non-cooperative situation made frequent big changes to avoid a collision. In the case of the experiment using four ships, there was no collision in the cooperative situation regardless of the size of the safety domain, but a collision occurred between the ships when the size of the safety domain increased in cases of non-cooperation. In the case of experiments using eight ships, it was found that there are optimal parameters for collision avoidance. Also, it was possible to grasp the variation of the sailing distance and the costs according to the combination of the parameters, and it was confirmed that the setting of the parameters can have a great influence on collision avoidance among ships.

• Journal of Internet Computing and Services
• /
• v.7 no.3
• /
• pp.31-39
• /
• 2006

Ubiquitous and pervasive environment presents opportunities for a rich set of location aware applications such as car navigation and intelligent robots, interactive virtual games, logistics service, asset tracking etc. Typical indoor location systems require better accuracy than what current outdoor location systems provide, Outdoor location technologies such as GPS have poor indoor performance because of the harsh nature of indoor environments, In this paper we present a novel reducing interference location system that is particularly well suited to support context aware computing. The system, called EEM (Enhance Envelop Method) alms to combine the advantages of real time tracking systems that implement distributed environment with the suitability of infrastructure sensor network.

• Journal of KIISE:Computing Practices and Letters
• /
• v.6 no.6
• /
• pp.555-568
• /
• 2000

The World Wide Web has become the largest virtual system that is almost universal in scope. In recent research, it has become effective to utilize idle hosts existing in the World Wide Web for running applications that require a substantial amount of computation. This novel computing paradigm has been referred to as the advent of global computing. In this paper, we implement and propose a mobile object-based global computing framework called Tiger, whose primary goal is to present novel object-oriented programming libraries that support distribution, dispatching, migration of objects and concurrency among computational activities. The programming libraries provide programmers with access, location and migration transparency for distributed and mobile objects. Tiger's second goal is to provide a system supporting requisites for a global computing environment - scalability, resource and location management. The Tiger system and the programming libraries provided allow a programmer to easily develop an objectoriented parallel and distributed application using globally extended computing resources. We also present the improvement in performance gained by conducting the experiment with highly intensive computations such as parallel fractal image processing and genetic-neuro-fuzzy algorithms.

• The KIPS Transactions:PartC
• /
• v.8C no.6
• /
• pp.775-782
• /
• 2001

Recently the use of Linux OS is increasing to tremendous figures. But due to the fact that Linux is distributed on an open-source policy, the need of security is an upcoming question which leads to widespread development of security on a Linux based environment. Cryptography, however, can cause various problems because of difficulty of key management. A lot of researchers have been concentrating on the key recovery technique to eliminate the reverse effect of using these kinds of security and to promote positive aspects of using it. In this thesis I am suggesting an mechanism based on the key recovery technique, as a method to save time in recovery and resetting a disconnection between two end-users through IPSec (IP Security) protocols in a VPN (Virtual Private Network) environment. The main idea of the newly suggested mechanism, KRFSH (Key Recovery Field Storage Header), is to store the information of the session in advance for the case of losing the session information essential to establish a tunnel connection between a SG and a host in the VPN environment, and so if necessary to use the pre-stored information for recovery. This mechanism is loaded on the IPSec based FreeS/WAN program (Linux environment), and so the VPN problem mentioned above is resolved.

• Journal of the Korea Society for Simulation
• /
• v.24 no.4
• /
• pp.11-21
• /
• 2015

If the cloud computing environment is not sufficiently provide the required resources due to the number of virtual server to process the request, may cause a problem that the load applied to the specific server. Migration administrator receive the resources of each physical server for improving the efficiency of the virtual server that exists in the physical servers, and determines the migration destination based on the simulation results. But, there is more overhead predicting the future resource consumption of all the physical server to decide the migration destination through the simulation process in large and complex cloud computing environments. To solve this problem, we propose an improved prediction method with the simulation-based approach. The proposed method is a fuzzy-logic based priority model for VM migration. We design a proposed model with the DEVS formalism. And we also measure and compare a performance and migration count with existing simulation-based migration method. FPLM shows high utilization.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.6 s.261
• /
• pp.635-643
• /
• 2007

As many engineers and technicians are involved in the design process of large scale and/or complex products, there are a lot of miss matches and interferences due to designers' faults and several kinds of CAD systems. Recently, CAD systems are applied to verify and check the assembly process. Digital Mock-Up(DMU) system, a tool to build a virtual mock-up in the design stage, has been used to prevent the interferences and miss matches during precision design processes. Using the virtual assembly tool, engineers are able to design precision and interference free parts without physical mock-ups. Instead of a single CAD source, several CAD systems are used to design a complex product. Several organizations are involved in the distributed design environment for heterogeneous multi-CAD assembly. XML and the lightweight CAD file are proposed for the multi-CAD assembly. XML data contains hierarchy of the heterogenenous multi-CAD assembly. STEP PDM schema and STEP ISO 10303-28 formations are applied to construct the XML data. The lightweight CAD file produced from various CAD files through ACIS kernel and InterOp not only contains mesn, B-Rep and topological data, but also is used to visualize CAD data and to verify dimensions. Developed system is executed on the desktop computers. It does not require commercial CAD systems to visualize 3D assembly data. Real-time interference and fitness checks, dimensional verification, and design and assembly verification are performed on the developed system. Assembly of heterogeneous models for a car is conducted to verify the effectiveness of the developed DMU system on the Internet.