• Aerospace Engineering and Technology
• /
• v.11 no.1
• /
• pp.103-110
• /
• 2012

In the COMS satellite mission operation, more large meteorological images such as Full Disk(FD) image or 2 adjacent Extended Northern Hemisphere(ENH) images can be taken by the time shift of East West Station Keeping(EWSK) maneuver when the EWSK conflicts with the large images. In this study an analytical approach based on probability of the conflict is proposed for theoretical analysis about the EWSK time shift to avoid the conflict with FD or 2 ENH images. The EWSK time shift has been applied to the COMS operation as a test, too. The theoretical study result and test operation outcome are synthesized to provide the analysis of impact on the COMS fuel consumption by the EWSK time shift. This study is expected to contribute to the maximization of COMS meteorological mission application.

• Journal of KIISE:Databases
• /
• v.36 no.6
• /
• pp.422-433
• /
• 2009

As an effort to secure Semantic Web, in this paper, we introduce an RDF access authorization model based on an ontology hierarchy and an RDF triple pattern. In addition, we apply the authorization model to RDF query validation for approved access authorizations. A subscribed SPARQL or RQL query, which has RDF triple patterns, can be denied or granted according to the corresponding access authorizations which have an RDF triple pattern. In order to efficiently perform the query validation process, we first analyze some primary authorization conflict conditions under RDF subsumption inference, and then we introduce an efficient query validation algorithm using the conflict conditions and Dewey graph labeling technique. Through experiments, we also show that the proposed validation algorithm provides a reasonable validation time and when data and authorizations increase it has scalability.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.1
• /
• pp.233-241
• /
• 2010

CoSlide is a collaborative system, extending the Jakarta Slide WebDAV server. The CoSlide server provides group workspaces for collaborators. CoSpace is a client which supports various collaborative authoring activities on the CoSlide server through the WebDAV protocol. CoSpace provides graphic user interfaces to support effective interaction among the collaborators, managing the shared resources for them. However, during collaboration, simultaneous modifications on the content of shared resources might cause conflicts among the content of the revisions made by the collaborators, leading to serious problems on project progress. In this paper, we describe an extension of the CoSpace client to solve the problem. The extended CoSpace client supports the remote version management facility through which the collaborators can manage the versions of the associated server resources in the distance. Also, to identify the changes of the text files such as program source codes, the extended client provides the facility for comparing two versions and displaying the differences in a visual manner. In addition, it provides the version management of a whole workspace and the removal of all the unnecessary versions of the designated resources.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.4
• /
• pp.730-736
• /
• 2012

PN(Pseudo Noise) sequences play an important role in wireless communications, such as in a CDMA(code division multiple access) communication system. If there is a crash when multiple users simultaneously connected to a system, then PN sequences with low correlation help to minimize multiple access interference in such communication system. In this paper we propose a family of non-linear extended binary sequences with low cross-correlations and the family include $m$-sequence, GMW sequence, Kasami sequence and No sequence with optimal cross-correlation in terms of Welch bound. And we analyze cross-correlation of these sequences.

• Proceedings of the Korea Technology Innovation Society Conference
• /
• 2017.05a
• /
• pp.461-471
• /
• 2017

지난 2017년 1월 17일, 우리나라는 재난 및 안전관리기본법의 자연재난에 우주물체의 추락 충돌로 인한 재난을 포함시켰다. 이는 '14 진주운석 추락 등 잇따른 우주재난에 대한 국제적 관심고조 및 이에 대한 대비의 필요성 제기 등이 바탕이 된 것으로, 우주재난에 대한 국가적 관리의 필요성이 현안에 반영된 결과이다. 한편, 기존정책의 범위가 축소되거나 확장되는 등 변화가 발생할 때 해당 정책이 효과적으로 집행되기 위해서는 정책의 실질적 집행 효과를 경험하는 대상이 되는 정책적 고객이 정책의 변경내용을 인지하고 해당 정책에 대하여 공감하는 것이 중요하다. 우주재난의 경우 재난 및 안전관리기본법에 기존에 포함되어있던 기타 자연재난과 비교할 때, 그 위험도나 피해정도 등이 대중에게 어떠한 평가를 받고 있으며, 특히 기타 자연재난과 비교할 때 같은 맥락으로 이해되고 있는지를 파악하여 향후 세부 정책에 반영할 필요가 있을 것으로 판단된다. 이에 본 연구에서는 "우리나라 국민의 우주위험인식 수준과 국가 재난정책"의 후속연구로서 2016년 9월 발생한 경주지진 전 후 자연재난에 대한 국민의 인식에 변화가 있는지를 분석하여 이를 토대로 우주재난에 대한 국민의 인식을 설명하고 정책적 시사점을 제시하고자 한다.

• Journal of IKEEE
• /
• v.2 no.1 s.2
• /
• pp.42-52
• /
• 1998

This paper proposes an extended TCP/IP protocol, LAN/TCP, that can be used for the distributed soft real-time systems connected through the Ethernet-based local area network. Since LAN/TCP shows soft real-time performance with keeping compatibility and interoperability with the standard TCP/IP, the existing application software can be used without any modification. LAN/TCP also provides the periodic transmission mode(PTM) with which the periodical data collection and updating the control signals can be efficiently implemented with relatively small traffic overhead. This paper includes the computer simulation and experimental results of the proposed protocol.

• Journal of Korea Society of Industrial Information Systems
• /
• v.26 no.1
• /
• pp.31-40
• /
• 2021

The important goal of the unmanned vehicle technology is on controlling the direction and speed of the vehicle with information acquired from various sensors, without the intervention of the driver, until the vehicle reaches to its destination. In this paper, our focus is on developing an unmanned conveyance system by exploiting low-cost sensing technology for indoor factories or warehouses, where the moving range of the vehicle is limited. To this end, we propose an architecture of a scalable automated conveyance system. Our proposed system includes a number of unmanned conveyance vehicles, and the efficient control mechanism of the vehicles without neither conflicts nor deadlock between the vehicles being simultaneously moved. By implementing the real prototype of the system, we successfully verify the efficiency and functionality of the proposed system.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2022.05a
• /
• pp.252-255
• /
• 2022

기존 블록체인 기술을 활용해 새로운 비즈니스 모델을 개발 및 투자하려는 기업들의 관심이 높아지고 있으나, 낮은 확장성으로 인해 기존 블록체인 기술만으로는 시장에서 활용되기 어렵다. 블록체인의 낮은 확장성을 해결하기 위해 검증된 참여자만 참여하는 프라이빗 블록체인과 프라이빗 블록체인 고속화를 위한 관련 연구가 같이 진행되고 있다. 삼성의 넥스레저는 하이퍼레저 패브릭의 다중 버전 동시성 제어(MVCC) 충돌로 인한 낮은 TPS 문제를 해결하기 위해 Accelerator를 추가하여 고속화를 진행하였다. 하지만 모든 트랜잭션을 수집하여 처리하는 방식인 Accelerator는 중앙화로 인해 악의적인 공격 타깃이 되어 단일 장애 지점 문제가 발생할 수 있으며, 공격으로 인해 위조되거나 분실된 데이터는 검증 없이 블록체인 블록에 반영되고, 한번 반영된 데이터는 수정이 어렵다. 본 논문에서는 이와 같이 프라이빗 블록체인 고속화 상황에서 발생할 수 있는 단일 장애 지점 문제를 해결하기 위해 CMT와 사기증명 기반의 고속화 하이퍼레저 패브릭 시스템을 제안했으며, 제안한 시스템을 구축하고 성능 테스트를 통해 CMT 하이퍼레저 패브릭 시스템 성능이 99.58% 유지됨과 사기증명이 가능함을 확인하였다.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.9
• /
• pp.825-830
• /
• 2009

Pharmaceutical compounds enter the water environment through the diverse pathways. Because their concentration in the water environment was frequently detected in the level of ppt to ppb, the monitoring system should be optimized as much as possible for finding appropriate management policies and technical solutions. One Factor At a Time (OFAT) approach approximating the response with a single variable has been preferred for the optimization of LC-MS/MS operational conditions. However, it is common that variables in analytical instruments are interdependent. Therefore, the best condition could be found by using the statistical optimization method changing multiple variables at a time. In this research, response surface analysis (RSA) was applied to the LC-MS/MS analysis of emerging antibiotic compound, sulfamethoxazole, for the best sensitivity. In the screening test, fragmentation energy and collision voltage were selected as independent variables. They were changed simultaneously for the statistical optimization and a polynomial equation was fit to the data set. The correlation coefficient, $R^2$ valuerepresented 0.9947 and the error between the predicted and observed value showed only 3.41% at the random condition, fragmentation energy of 60 and collision voltage of 17 eV. Therefore, it was concluded that the model derived by RSA successfully predict the response. The optimal conditions identified by the model were fragmentation energy of 116.6 and collision voltage of 10.9 eV. This RSA can be extensively utilized for optimizing conditions of solid-phase extraction and liquid chromatography.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.1
• /
• pp.354-372
• /
• 2020

This study analyzed how North Korean defectors recognized and overcame conflict in the South Korean job culture during the course of entering and settling into South Korea, and the association between their old career and adaptation within their new careers. The study selected 13 employed participants who entered South Korea more than five years ago and experienced working. Interviews were conducted over the course of five years. The topics were analyzed after performing interviews 60 to 120 minutes long by recording and transcribing the recordings and using semi-structured questionnaires for the 13 people. The results reflected the job environment in North Korea, their career background, factors for a successful new life, their constant efforts for employment, the difficult adaption to South Korean life, pursuing job stability, accepting South Korean culture, and career compromises. The results of this study are as follows. First, they undergo difficulty in the course of selecting jobs due to the converted environment from passivity to autonomy. Second, they cannot use their previous job history and they complained about prejudice and the lack of job information. Third, major problems included their lack of adaptability, stress, and loss of economic power. The study suggests that these North Korean defectors undergo an integrated course of cultural learning. Fourth, they were hardly able to adapt. Fifth, they tried to overcome conflicts of job culture according to their personal characteristics.