• Journal of Technologic Dentistry
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• v.39 no.1
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• pp.35-42
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• 2017

Purpose: The purpose of this paper was to evaluate the occurrence of errors regarding adaptation by conducting a three-dimensional assessment comparing the bridge type dental restoration after the cutting process, which has multiple abutments, with a single type dental restoration. Methods: By using ten identical files obtained by scanning the master model, thirty designs were created consisting of ten maxillary right first premolars and ten maxillary right first molars with single crown abutments, along with ten bridge designs with the identical abutment. A 5-axis milling machine was used to produce the design file. The produced denture prostheses were scanned using a silicone replica for a STL file. An evaluation was conducted using 3D analysis software on the master model and each of the thirty data files. Results: The RMS value of the pre-molar (14) was $38.4{\pm}4{\mu}m$ for single and $54.7{\pm}6{\mu}m$ for bridge abutment; therefore, a statistically significant difference was observed for single and bridge designs although both shared the same abutment form (P<.05). Also, the RMS value of the molar (16) was $47.6{\pm}2{\mu}m$ and $56.6{\pm}5{\mu}m$ for the single and bridge designs, respectively, thereby presenting a statistically significant difference (P<.05). Conclusion: As a result, dental prosthesis fabricated using the single method presented better internal adaptation outcomes.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.6
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• pp.345-352
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• 2015

Recently, by developing many training systems in battle field, the demand for interconnecting and internetworking between Live, Virtual, Constructive training systems has been increased to support efficient data distribution and system control. But, there are lots of problems for them to interwork, because the existing researches only support L-L, V-V, C-C Interoperability. Therefore, we propose L-V-C gateway to provide interoperable simulation environment based on HLA and DDS between them. First, we illustrate FOM Management that parses RPR-FOM XML file to acquire Data information to be shared between them, and generates common data structure and source code used for L-V-C Gateway. L-V-C Gateway created from FOM Management supports Data Conversion and Quality of Service between HLA and DDS. HLA Federate and DDS Domainparticipant in L-V-C Gateway play a role of logical communication channel and relay data from HLA Federation to DDS Domain and vice versa.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.113-116
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• 2000

파일 시스템에서 문제가 발생했을 때, 지속적인 서비스를 제공하기 위해서 보다 빠른 회복이 요구된다. 기존의 파일 시스템은 fsck를 이용하여 시스템을 회복하는데 많은 시간이 필요하고, 회복 중에 오프라인 상태를 요구하기 때문에 서비스가 중단되는 단점이 있다. 따라서, GFS와 같은 공유 디스크 파일 시스템에서는 저널링을 이용하여 온라인 상태에서의 회복을 가능하게 하고 회복 시간을 단축시키는 효과를 거두었다. 그러나, 한 클라이언트가 디스크의 메타데이터를 수정하는 중에 다른 클라이언트가 동일한 블록을 사용하고자 할 때, 앞의 클라이언트가 메타데이터를 디스크 저널에 기록한 후 다시 디스크에 기록하기까지 기다린 후에 디스크에 접근하여 사용할 수 있다. 이처럼 동일한 블록을 사용하더라도 불필요한 디스크 접근이 발생한다. 본 논문에서는 이러한 문제점을 해결하기 위해서 클라이언트에서 클라이언트로 메타데이터를 직접 넘겨줄 수 있도록 개선한다. 성능 분석 결과 이러한 개선 방안이 기존의 저널링보다 디스크 접근 횟수를 줄임으로써 트랜잭션 처리 시간을 줄이는 결과를 얻을 수 있다.

• Journal of Korean Library and Information Science Society
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• v.18
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• pp.217-243
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• 1991

Authority control enables us to retrieve information accurately by coordination and cross reference of headings. It is considered that authority control is needed in machine readable catalogs as well as in conventional catalogs. Taylor, Maxwell and Frost divided automated authority control systems into major vendor and network systems then available into two groups. The first group was defined as a system that processes a library's machine readable catalogs on the tape against an automated authority file. The second group offers an online access to catalogs and authority records. This group was further subdivided into linked or integrated systems and unlinked systems. If authority work is shared with many libraries the costs can be considerably reduced and the quality of catalog data base can be controled by standardization of headings used in participating libraries. The NACO is a project for sharing of authority records started in 1977 by L.C. And LSP furthers the ability to share authority records. A project as the NACO is necessary not only in America but also in the other countries The responsible organizations for national bibliographies of the countries must take much interest in these matters.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.786-788
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• 1999

파이버채널은 고용량 디스크를 특성 호스트에 의존하지 않고 네트웍에 직접 연결할 수 있는 매우 빠른 입출력 시스템 인터페이스이다. 파이버채널의 등장에 따라 고용량 디스크 어레이를 공유하는 분산 파일시스템에 관한 관심이 늘고 있다. 본 논문에서는 파이버 채널의 장점을 이용하여 효율적인 공유디스크 분산 파일시스템의 설계 결과를 제시한다. 제시된 파일시스템은 시스템에 참여하는 모든 호스트들이 부하를 균등하게 나누어 부담하도록 설계되었으며 특히 호스트들이 파이버채널상에서 직접 통신을 통하여 공유디스크 데이터의 일관성을 유지할 수 있도록 하므로써 별도의 장치 없이 일반디스크를 사용할 수 있도록 하여 비용대 성능비가 우수한 시스템에 적합하도록 하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.4-6
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• 2001

본 논문에서는 SAN(Storage Area Network) 기반의 공유파일시스템인 Asphodel 파일 시스템을 이용하여 를러스터 웹 서버를 구성하였다. 그리고 Asphodel 공유 파일 시스템이 가지는 락(lock) 서버를 이용하여 효율적인 웹 분배 정책인 CARD(Cache-Aware Request Dispatch)를 제안하고 이를 설계 구현하였다. 그 결과 후위 서버의 메모리 캐쉬의 적중률을 높임으로써 보통의 분배 정책인 라운드로빈(Round-Robin) 방식에 비해 웹 서버의 throughput과 latency에서의 성능 향상을 보였다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.661-663
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• 2004

본 논문에서는 SAN 기반 공유 파일 시스템인 SANfs의 fault-tolerance를 보장받기 위해 fault-tolerant server인 shadow server를 구현하였다 SANfs(1)는 SAN에서 Network-attached storage에 접근하는 여러 클라이언트가 서로의 데이터를 공유할 수 있도록 도와주는 파일시스템이다. SANfs에서 파일 관리를 위해 meta server를 두고 있으며, 이 서버에서 네트워크를 통해 접근하는 털러 클라이언트의 request를 관리한다. SAMfs에서는 meta server를 통해 중앙 집중식으로 파일시스템을 관리하고 있기에 meta server가 fault가 나게 되면 전체 시스템의 동작이 멈추게 되는 single point-of-failure의 문제가 생기게 된다. 본 논문에서는 meta server가 fault가 났을 경우에도 지속적으로 서비스를 할 수 있도록 shadow server를 두었으며. 이 서버가 meta server의 이상 시 그 기능을 대행하도록 하였다. 본 논문의 shadow server는 평상시에 meta server와 파일시스템의 metadata의 동기를 맞추고 있으며, 이 정보를 가지고 meta server로 그 기능을 전환하였을 때 서비스를 해 주도록 하고 있다. 상대 서버의 이상 유무의 판단은 heartbeat를 통해 이루어지고 있으며, meta server로의 failover는 heartbeat의 주기에 영향을 받음을 실험을 통해 알게 되었다.

• Journal of Information Technology Applications and Management
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• v.10 no.3
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• pp.1-22
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• 2003

P2P systems have been studied by many researchers in universities and commercial firms in recent years. In this study. we design and implement a system that makes UP for shortcomings of currently available P2P systems. Gnutella and Napster. The study also includes an efficiency analysis scheme conducted through a series of experimental data. The data sharing system of the study demonstrated duality of roles(client, service) of peers. But, their roles were separated from the existing client-server systems. Also, the study implements mechanism that shows the redundancy of data to communicate efficiently among peers for transferring data. The results of performance measure of the system shows that the amount of information shared by peers increases as the amount of peers increases but with no significant increase in response time. This constant response time is far more stable and faster than current file sharing systems. such as Gnutella and Napster. Business applications such as knowledge management, enterprise information portal management and transfer of data are done by use of supercomputers. They need to extend their systems to equip with more capacity and throughput as the number of clients increases. Moreover, they will face with more complicated problems if integration with new systems exists. If this JDSS is introduced to these business applications. it would easily augment scalability of the system with high performance at less expense.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.5
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• pp.901-909
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• 2021

Since mobile devices have limited computational resources, it tends to use the cloud to compute or store data. As real-time becomes more important due to 5G, many studies have been conducted on edge clouds that computes at locations closer to users than central clouds. The farther the user's physical distance from the edge cloud connected to base station is, the slower the network transmits. So applications should be migrated and re-run to nearby edge cloud for smooth service use. We run applications in docker containers, which is independent of the host operating system and has a relatively light images size compared to the virtual machine. Existing migration studies have been experimented by using network simulators. It uses fixed values, so it is different from the results in the real-world environment. In addition, the method of migrating images through shared storage was used, which poses a risk of packet content exposure. In this paper, Containers are migrated with Secure CoPy(SCP) method, a data encryption transmission, by establishing an edge computing environment in a real-world environment. It compares migration time with Network File System, one of the shared storage methods, and analyzes network packets to verify safety.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.375-384
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• 2001

The shared disk file systems use a technique known as file system journaling to support recovery of metadata on the SAN(Storage Area Network). In the existing journaling technique, the metadata that is dirtied by one host must be updated to disk space before some hosts access it. The system performance is decreased because the disk access number is increased. In this paper, we describe a new recovery technique using a global buffer to decrease disk I/O. It transmits the dirtied metadata into the other hosts through Fibre Channel network on the SAN instead of disk I/O and supports recovery of a critical data by journaling a data as well as metadata.