• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.753-758
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• 2005

This study attempts at building an integrated GIS computing framework for evaluating space-time accessibility of an individual with the approach of time geography model. The proposed method is based on the integration of mobile GIS and object-relational spatio-temporal database. Three components are central to our system: ( i ) mobile GIS application that transmits spatio-temporal trajectory data of an individual; ( ii ) spatio-temporal database server that incorporates the time geography model; and (iii) geovisualization client that provides time geographic queries to the spatio-temporal database. As for the mobile GIS application, spatio-temporal trajectory data collected by GPS-PDA client is automatically transmitted to the database server through mobile data management middleware. The spatio-temporal database server implemented by extending a generic DBMS provides spatio-temporal objects, functions and query languages. The geovisualization client illustrates 3D visual results of the queries about space-time path. space-time prism and space-time accessibility. This study shows a method of integrating mobile GIS and DBMS for time geography application, and presents an appropriate spatio-temporal data model for evaluating space-time accessibility of an individual.

• IEMEK Journal of Embedded Systems and Applications
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• v.1 no.2
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• pp.73-81
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• 2006

The home network is generally separated from the Internet, as it is made up of a private network due to security issues and the lack of IPv4 addresses space. Also, a user may want to move from a terminal to another terminal connected in the home network during communicating with people outside the home. In this case, people connected in the Internet, or another home network could not communicate the user at the home. These limitations prevent a SIP-capable device connected in the home network from communicating with another SIP-capable device connected in the Internet or the outside of the home network. To overcome the limitations, This paper proposes the Adaptive SIP Application Server System as a software architecture that a user inside of the home can communicate with people outside of the home when the home is composed of a private IP-based network. Moreover, the proposed architecture provides the session mobility that allows the user to maintain a media session even if changing the terminal inside of the home during the session established. The proposed system was implemented over a home server device which acts functionality as a connection point for transmitting IP packets between a home network and the Internet.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.9
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• pp.847-854
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• 2004

In this paper, It is studied to control and to monitor the remote system state using HTTP(Hyper Text Transfer Protocol) object communication. The remote control system is controlled by using a web browser or a application program. This system is organized by three different part depending on functionality-server part, client part, controller part. The java technology is used to composite the server part and the client part and C language is used for a controller. The server part is waiting for the request of client part and then the request is reached, the server part saves client data to the database and send a command set to the client part. The administrator can control the remote system just using a web browser. Remote part is worked by timer that is activated per 1 second. It gets the measurement data of the controller part, and then send the request to the server part and get a command set in the command repository of server part using the client ID. After interpreting the command set, the client part transfers the command set to the controller part. Controller part can be activated by the client part. If send command is transmitted by the client part, it sends sensor monitoring data to the client part and command set is transmitted then setting up the value of the controlled system.

• Journal of Information Technology and Architecture
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• v.9 no.1
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• pp.67-78
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• 2012

Organizations have many physical servers in their departments such as application servers, web servers, database servers, mail servers, and so forth. The problem of server sprawl is common in information system centers of most profit and nonprofit organizations. Server sprawls are characterized by the use of dedicated servers for single applications. This server sprawl causes the problems such as the low resource utilization, the large space consumption, and the high management cost. Server consolidation is crucial to solve these problems by providing savings in hardware, software, maintenance, facility, and labor costs. This paper proposed a method to implement server consolidation for public organizations by the NDMS(National Disaster Management Systems) case study.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.456-461
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• 2018

Until the 4th Industrial Revolution fused the Web with diverse technologies, the only factor in evaluating the performance of a Web application was the loading speed of the Web application. Therefore, most existing Web application performance analysis tools focus on the speed at which Web applications run in a Web browser. However, the web is now being used not only in a simple web browser but also in a variety of services. So, in addition to simple speed, there are more elements to be checked to evaluate web applications. Therefore, in this paper, we design a server to perform web application performance analysis considering progressive web app, accessibility, best practice, and search engine optimization as well as the above mentioned speed. Also, we realize a REST API based server that can provide web application performance services without being affected by user's devices or environment.

• Journal of Korean Society of Forest Science
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• v.110 no.1
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• pp.72-81
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• 2021

We developed smartphone application and web application server to acquire and effectively manage tree measurement information. Smartphone applications can measure tree height, diameter at breast height (DBH), azimuth, altitude, slope, and positional coordinates using augmented reality (Google AR core) and motion sensors. The web application server effectively manages and stores measurement information. To evaluate the accuracy of information acquired using a smartphone, 90 Korean pine trees (Pinus koraiensis) were randomly selected from a natural mixed forest, with a total of 90 representative trees randomly collected from a natural mixed forest. Then, height and DBH were measured using a Haglof Vertex Laser Hypsometer and caliper. Comparisons of the results indicated significant results at the 95% level and a very high average correlation of 0.972 for both tree height and DBH. In terms of DBH, the average errors were 0.6745 cm and 1.0139 cm for artificial coniferous and natural mixed forests, respectively.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.9
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• pp.223-228
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• 2016

Nowadays users of Virtual Environment are want to play with thousands of players in an evolving virtual world at the same time over the internet. So, the load of this kind of Virtual Environments is heavier than that of any other precedents. One of load balancing methods is map-partition to divide the load of entire system which is vulnerable to delay message between clients and servers. In this paper, we propose a Migration Agent application server architecture using to help migration of player character between field servers and to reduce response time between clients and field servers. Migration Agent is reduce Player Character's responds time as Cache Server, if Player Character move to another Field Server, Player Character need the synchronization process in the DBMS approach, to minimize response time by reducing the period for cross - Player Character Field Server to perform the role. Field Server by placing them in form of a stack existing form of grid, for load concentrated on a specific server.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3B
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• pp.105-113
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• 2005

In this paper, through the implementation of the application service, we evaluated the feasibility and availability of the staged application service platform, which is based on the sharing of the PVM cluster. Application service platform provides three managers for dividing the request processing steps into two stages, such as a request processing stage and a service providing stage. Three managers and its relation to the divided stages are as follows, service manager and load manager to distribute the request in front-end server for a request processing stage, job manager in clustered(back-end) servers for a service providing stage. The experiment shows that the staged application service platform provides more stable and scalable characteristics and better performance improvement on the dynamic load changes than the single server system. And also it shows that real application service system can be implemented easily without modification of the proposed service platform.

• The KIPS Transactions:PartA
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• v.15A no.4
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• pp.199-210
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• 2008

A Clustering based wireless internet proxy server needs a layer-7 load balancer with URL hashing methods to reduce the total storage space for servers. Layer-4 load balancer located in front of server cluster is to distribute client requests to the servers with the same contents at transport layer, such as TCP or UDP, without looking at the content of the request. Layer-7 load balancer located in front of server cluster is to parse client requests in application layer and distribute them to servers based on different types of request contents. Layer 7 load balancer allows servers to have different contents in an exclusive way so that it can minimize the total storage space for servers and improve overall cluster performance. However, its scalability is limited due to the high overhead of parsing requests in application layer as different from layer-4 load balancer. In order to overcome its scalability limitation, in this paper, we propose a distributed layer-7 load balancer by replacing a single layer-7 load balancer in the conventional scheme by a single layer-4 load balancer located in front of server cluster and a set of layer-7 load balancers located at server cluster. In a clustering based wireless internet proxy server, we implemented the conventional scheme by using KTCPVS(Kernel TCP Virtual Server), a linux based layer-7 load balancer. Also, we implemented the proposed scheme by using IPVS(IP Virtual Server), a linux-based layer-4 load balancer, installing KTCPVS in each server, and making them work together. We performed experiments using 16 PCs. Experimental results show scalability and high performance of the proposed scheme, as the number of servers grows, compared to the conventional scheme.

• Journal of Internet Computing and Services
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• v.6 no.6
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• pp.71-83
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• 2005

In this paper, we developed the Distributed Programming Developing Tool(DPDT) which can make distributed application program efficiency based on the distributed object group framework supporting group management and dynamic binding for object resources requested from clients on distributed systems. The distributed object group framework we constructed provides not only the group register/withdraw, the access right and the name/property services for server objects from a point of view of group management services, but also dynamic binding, replicated object supporting, load balance, and federation among the object groups from a point of view of the supporting services of distributed application, When developing distributed application, by using our tool, server programming developer implements objects in each server system, next registers the properties to need for service provision to the object group. Client programming developer can also develop client program easily by obtaining the access right for the object or the object group and using the properties of objects with the access right permitted to the client. For providing above application developing environment in this paper. we described the definition of object group, the architecture of the distributed object group framework which our tool supports, and its functionalities, then specified the 3 GUI environments of DPDT implemented for providing efficient interfaces between the distributed object group and distributed applications. Finally, by using the DPDT, we showed the group register/withdraw and the access right grant procedure of objects which are server programs, the developing process of client program, and the executing results of the distributed application developed.