• The KIPS Transactions:PartC
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• v.10C no.2
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• pp.199-208
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• 2003

LDAP (Lightweight Directory Access Protocol) Directory Service provides information for locating resources like files and devices over the network such as Internet or Intranet. Since LDAP is widely accepted as one of the standard directory service structure for the Internet, it is desirable that a group of LDAP servers works transparently and continuously even if the related network partitions temporally, through maintaining replicated directory information among those LDAP servers. In this paper, we describe the design and implementation of a robust LDAP sewer, which runs as a process group in JACE group communication system, and the associated LDAP service provider which enables Java applications to use the developed LDAP directory service.

• Journal of Internet Computing and Services
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• v.3 no.1
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• pp.91-99
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• 2002

Many companies and departments are increasingly concerned of searching their business information in correct and faster way as they share the information through the internet. LDAP has been proposed for directory server standards which supports storing, searching and managing the business information, and it has become a global standard. Current LDAP, however, cannot solve problem; such as server overloads and data synchronization. This paper describes the history and characteristics of LDAP, and proposes an architecture for solving those problem;. Since the proposed architecture is designed based on the existing LDAP architecture, it guarantees extensibility and portability of server configuration.

• Journal of the Korea Society for Simulation
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• v.14 no.2
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• pp.1-13
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• 2005

In distributed replicating server model, providing replicated services is able to improve the performance of providing a service and efficiency for several clients. And, the composition of the server selection algorithm is efficiently able to decrease the retrieval time for replicated data. In this paper, we define the system model that selects and connects the replicated server that provides optimal service using server-side downstream measurement and proposes an applicable algorithm.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.4
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• pp.25-37
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• 2004

A certificate is expected to use for its entire validity period. However, a false information record of user and compromise of private key may cause a certificate to become invalid prior to the expiration of the validity period. The CA needs to revoke the certificate. The CA periodically updates a signed data structure called a certificate revocation list(CRL) at directory server. but as CA updates a new CRL at directory server. the user can use a revoked certificate. Not only does this paper analyzes a structure of CRL and a characteristic of certificate status conviction, OCSP method but also it proposes a new certificate status verification method adding an observer information in handshake process between user and server.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.77-82
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• 2016

Recently, an IoT(Internet of Things) application communication protocol is standardizing for connectivity between every things on Internet. In this paper, we design and implement an indoor resource control service using IETF (Internet Engineering Task Force) CoAP (Constrained Application Protocol) based on Web. We present an indoor resource control architecture based on Web included functionalities of proxy and RD (Resource Directory) in a web server. Developed indoor resource control service supports to register low-powered and small-scale IoT nodes to web server using CoAP. This service allows users to control the indoor resources through a web browser using Web proxy with functionality of HTTP-CoAP converting.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.147-153
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• 2016

Recently, IETF (Internet Engineering Task) working group has adopted CoAP (Constrained Application Protocol) as a standard IoT proctocol. CoAP is a specialized web transfer protocol for use with constrained nodes and constrained environment such as small memory and low power networks. In this paper, we design and implement a registration service with CoAP protocol based on RD(Resource Directory) to connect IoT nodes in mobile Internet environments. The resource directory between the mobile terminal and IoT nodes provides to discover the IoT nodes and get the context data. The mobile terminal has as the CoAP client and embedded IoT nodes includes as the CoAP server so that it can conveniently manage the constrained IoT nodes to get the context data and control devices in a mobile environments.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.4
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• pp.303-307
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• 2002

Virtual hosting is a typical service to connect each directory of site and domain name. If traffic amounts may increase at one site present in the server, then it affects traffic amounts of other sites as well (including the sites which have flew requests). To overcome this problem, we suggest a simple feedback-control concept for the system by periodically monitoring the traffic and properly actuating traffic dispersions by investigating the log file. Specifically, large files are to be served in a backup server (to reduce the workload of the main server) by changing their own URL's in html format. In other words, it automatically redistributes the workload by using the URL. Furthermore, we also use the redirecting method by just adding html tags to html header. This method efficiently handles the workload and maintains the capability of the server effectively to the varying workload.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.430-432
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• 2001

LDAP 디렉토리(Directory) 서비스는 인터넷이나 인트라넷 등 네트워크 상에 있는 파일이나 장치들과 같은 자원 등의 위치를 찾을 수 있도록 정보를 제공한다. 따라서 다수의 LDAP 서버들 사이에 디렉토리 정보를 중복하여 유지함으로써 특정 서버와의 네트워크 단절(partition)과 같은 결함이 발생되는 상황에서도 투명하고 지속적으로 서비스를 제공하는 것이 바람직하다. 본 논문에서는 JACE 그룹통신 시스템을 이용하여 프로세스 그룹으로 동작하는 LDAP 서버와 자바 응용프로그램에서 서비스를 사용할 수 있도록 그룹 통신을 이용하여 LDAP 서비스 프로바이더를 설계하고 구현하였다.

• The KIPS Transactions:PartA
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• v.13A no.4 s.101
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• pp.343-350
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• 2006

In this paper, wireless internet proxy server clusters are used for the wireless internet because their caching, distillation, and clustering functions are helpful to overcome the limitations and needs of the wireless internet. A wireless Internet proxy server cluster needs a systematic scalability, simple communication structure, cooperative caching, and serving Hot Spot requests. In our former research, we proposed the CD-A structure which can be scalable in a systematic way and has a simple communication structure but it has no cooperative caching. A hash based load balancing can be used to solve the problem, but it can not deal with Hot Spot request problem. In this paper, we proposed a shared storage based wireless internet proxy server cluster which has a systematic scalability, simple communication structure, cooperative caching, and serving Hot Spot requests. The proposed method shares one cache directory and it has advantages: advantages of the existing CD-A structure, cooperative caching, and serving Hot Spot requests. We performed experiments using 16 PCs and experimental results show high performance improvement of the proposed system compared to the existing systems in Hot Spot requests.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.57-66
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• 2006

In this paper. proposes Multi_Kerberos certification mechanism that improve certification service of based on PKINIT that made public in IETF CAT Working Group. This paper proposed to a certificate other realm because search position of outside realm through DNS and apply X.509 directory certification system, to get public key from DNS server by chain (CertPath) between realms by certification and key exchange way that provide service between realms applying X.509, DS/DNS of based on PKINIT, in order to provide regional services. This paper proposed mechanism that support efficient certification service about cross realm including key management. the path generation and construction of Certificate using Validation Server, and recovery of Session Key. A Design of Multi_Kerberos system that have effects simplify of certification formality that reduce procedures on communication.