• Journal of Advanced Navigation Technology
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• v.21 no.5
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• pp.491-500
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• 2017

This paper investigates a low cost dual modular redundancy system based on heartbeat which can be applied to traffic control signal system. Failure of the traffic control signal system can cause traffic confusion and traffic accidents. Therefore safety and reliability of traffic control should be secured using fault tolerance technology. To do this, we configured a redundant board using the open source hardware and the heartbeat technique of Linux HA. The function of the traffic signal control system was verified and the fault recovery time was measured using fault injection test. As a result of the test, the fault recovery time was confirmed to be less than 9 seconds on average, confirming that the reliability target time is satisfied. Based on the results of this study, it is expected that it can be applied to fields requiring high reliability systems such as aviation, space, and nuclear power embedded systems.

• Journal of Broadcast Engineering
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• v.13 no.5
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• pp.612-621
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• 2008

Due to the various constraints such as feasible size of data payload and low transmission power, no technical specifications on the voice communication are included in the Zigbee standard. In this paper, a voice coding technique for application to the IEEE 802.15.4 standard, which is the basis of Zigbee communication, is presented. Here, both high compression and good waveform recovery are essential. To meet those requirements, a multi-stage discrete wavelet transform (DWT) block and a binary coding block consisting of two different pulse-code modulations are exploited. Theoretical analysis and simulation results in an indoor wireless channel show that the voice coder with 2-stage DWT is most appropriate from the viewpoint of compression and waveform recovery. When the line-of-sight component is dominant, the voice coding scheme has good recovery capability even in the moderate signal-to-noise power ratios. Hence, it is considered that the presented scheme will be a technical reference for the future recommendation of voice communication exploiting Zigbee.

• Resources Recycling
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• v.29 no.1
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• pp.43-52
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• 2020

The objectives of this study were to identify the optimal mix of foam concrete with the low-strength and high-flow for the repairing ground subsidence situation emergently by utilizing a large amount of industrial by-products and evaluate the possibility by applying it to the site. The factors of the experiment were the mixing ratio of mixing water and a foaming agent and the mixing ratio of foam over paste volume. The optimal mix identified by the experiment was applied to the field and basic properties were evaluated. The results of the experiment showed that the optimal mixing ratio of mixing water and the foaming agent was 10%. Moreover, when the mixing ratio of pre-foam over paste volume was 170%, it satisfied the target. However, to ensure stable quality when applying to the field, the foam mixing ratio was set 140% for the field application. The field application test of foam concrete with the low-strength and high-flow using an eco-friendly binder satisfied all target performances. Therefore, the possibility of using it as a mixture and construction method for a ground repair system is confirmed. However, there was a quality deviation between the upper part and the lower part due to the separation between foam and paste. Consequently, further studies are needed to improve it.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.1
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• pp.55-61
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• 2023

This study aims to develop CLSM fill material for emergency restoration using landfill coal ash. As a result of examining physical properties such as particle size distribution and fines content of landfill coal ash, bottom ash, fly ash, and general soil were mixed, and SP was found to have a density of 2.03 and a residual particle pass rate of 7.8 %. CLSM materials that secure fluidity in unit quantities without using chemical admixtures such as glidants and water reducing agents have a high risk of material separation due to bleeding. As a result of this experiment, it was found that the bleeding ratio did not satisfy the standard in the case of the specimen with a large amount of fly ash and a lot of addition of mixing water. As a result of the compressive strength test, the strength development of 0.5 MPa or more for 4 hours was found to be satisfactory for the specimens using hemihydrate gypsum with a unit binder amount of 200 or more, and the remaining gypsum showed poor strength development. Although it is judged that landfill coal ash can be used as a CLSM material, it is necessary to identify and apply the physical and chemical characteristics of coal ash buried in the ash treatment plant of each power generation company.

• Journal of the Korea Convergence Society
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• v.4 no.4
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• pp.1-5
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• 2013

This study aims to define the positive relationship among reverse logistics capability, firm's profits, and collaboration satisfaction. In the previous literatures about reverse logistics mainly focus on the importance of relationship between manufacturers and customers, but less likely on the potential positive effects of between collative firms. To implicate reverse logistics gives firms assets recovery, cost reduction through recycling which affects greater profits. Reverse logistics capability would be positively related with increasing profits for collaboration and satisfaction between partners.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.6
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• pp.662-673
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• 2003

This paper proposed a workflow enactment model to provide process management functions for the next generation Internet service environment such as Web Service and Grid Computing. The existing enterprise workflow enactment models could not meet the scalability and reliability requirements for aforementioned environments. To satisfy these requirements, this study addressed on applying P2P model to the workflow enactment model. Mathematical description and proof were employed to show the recovery based on set theory and we also showed performance enhancement through simulations, which demonstrated a comprehensive result giving more than 100 times fast response time than the existing centralized model on the same resources.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1998.12a
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• pp.201-210
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• 1998

전자상거래의 활성화를 위한 전자지불시스템은 보안성과 통용성의 양면을 만족해야한다. 현재 서비스중인 전자현금이나 전자화폐는 디지털정보가 직접 화폐가치를 지니고 있기 때문에 인터넷에서 분실시 복구가 불가능하다. 또한 전자수표나 가상은행을 이용한 계좌이체방식은 인터넷 통용성이 약하며, 신용카드를 이용한 전자지불시스템은 통용성은 양호하나 신용카드번호 노출의 위험이 있고 수수료 등 트랜잭션 비용이 소요되므로 소액지불에는 불리하다. 전자지불시스템의 활성화를 위해서는 신용카드와 같이 휴대 가능하고 실세계에서의 통용성이 우수한 시스템이어야 하며, 직접 지불이 가능하고 소액지불도 가능한 체계이어야 한다. 본 논문에서는 제안하는 새로운 지불시스템 "스마트-Pay"는 모든 사람들이 은행을 사용하고 있다는 점을 착안하여 은행계좌기반이면서 실세계 및 인터넷에서 직접지불이 가능하도록 설계한 것이다. 본 지불시스템의 안전도는 발행기관, 은행, 고객으로 이어지는 인증사슬에 의한 강력한 인증과 스마트카드에 의한 전자서명에 의존하며 기밀성, 무결성, 부인봉쇄를 제공하므로 안전하다고 평가된다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2016.11a
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• pp.319-321
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• 2016

본 논문에서는 지반함몰이 발생한 현장에 긴급복구를 위한 팽창기능제의 개발에 대한 내용이다. 현재 유동화토에 대한 기준이 없어 공동에 채워지는 채움재와 비슷한 압축강도인 0.3MPa을 기준으로 하여 흙의 일축압축시험 방법을 이용하여 실험을 진행하였다. 팽창기능제의 최적배합 실험과 팽창률에 따른 압축강도를 측정하여 뒤채움재로써의 기능 특성을 평가하였다. 실험결과, 팽창기능제 A의 경우 팽창률 750%이하에서 팽창기능제 B의 경우는 모든 실험체에서 목표 강도를 만족하였다.

• Information and Communications Magazine
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• v.25 no.4
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• pp.30-38
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• 2008

본고에서는 RUPI 규격이 포함하고 있는 여러 명세들 중에서 RUPI 서버에서 고려해야 되는 4가지 명세들-(1)다수 이종 로봇 클라이언트가 RUPI서버에 접속하였을 때 고가용성을 보장하는 'RUPI 서버 가용성', (2)원격에서 로봇 클라이언트의 상태를 진단하고 복구하는 '로봇 클라이언트 관리', (3)로봇 클라이언트에서 수행되기 어려운 응용 컴포넌트를 로봇 클라이언트를 대신하여 적재 및 관리하고 원격에서 실행하는 '로봇 클라이언트 응용 관리' 그리고 (4)상황인지 기반의 원격 로봇 응용 개발 및 운용을 위한 '원격 로봇 응용 프레임워크'-각각의 기술 규격에 대한 기본 개념을 소개한다. 또한 이들 각각의 기술들이 RUPI 서버 프레임워크에서 구현되기 위하여 만족해야 할 기술적 요구 사항들과 핵심 요소 기술들을 도출한다.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.193-195
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• 2003

최근 산업의 핵심 에너지원을 공급하고 있는 전력회사의 운영에서, 계통 사고시 대량의 경보 신호 발생으로 인하여 운전원의 혼란을 가져오게 되어, 사고후 복구시간의 지연을 초래하는 문제로 인한 해당산업체의 손실이 대형화하는 추세이다. 본 논문에서는 이와 같은 문제를 해결하는 방안으로 사고시 보호시스템의 순차정보를 이용하여 단시간에 고장진단을 수행함으로서, 고장의 원인 파악과 정확한 고장발생지점 정보를 운전원에게 제공할 수 있는 방법을 제안하고 있다. 고장진단 기법은 고장 발생의 불확실성을 고려한 보호시스템의 모델링 방법과 퍼지 페트리네트 기법을 개발하여 적용하였다. 본 연구에서 개발한 방법을 사례연구를 통하여 모델 계통에 적응하고 그 유효성 여부를 확인한 결과 만족할 만한 성과를 얻을 수 있었다. 특히 보호시스템의 오동작이나 부동작 둥의 불확실한 정보를 처리하는 데 본 연구에서 개발한 퍼지 페트리네트 기법이 탁월한 성능을 발휘하므로 실제의 대형 전력계통에 적용 가능성을 확인할 수 있었다. 또한 본 방법은 SCADA로부터 전송되는 실시간 데이터의 온라인 처리도 가능하므로 그 유용성은 아주 높다고 볼 수 있다.