• 한국인터넷방송통신학회논문지
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• 제11권4호
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• pp.17-22
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• 2011

수중 환경은 육상 환경과 많은 차이를 보이며 무선 통신에 사용되는 자원과 제약 조건들도 다르다. 일반적으로 수중 통신 환경은 육상 통신 환경보다 열악하고, 파도, 조류와 같은 해수의 흐름으로 인한 노드의 이동성 때문에 오류 발생 가능성이 기존의 지상 무선 센서 네트워크 보다 높다. 따라서 수중 무선 센서 네트워크의 통신 환경을 고려하여 노드 간 데이터 전송률을 향상시키기 위한 기법들에 대한 요구가 높아지고 있다. 본 논문에서는 수중 무선 센서 네트워크의 통신 환경을 고려하여 클러스터 헤드 노드의 오류 발생 시 이를 빠른 시간 내에 복구하기 위한 체크포인팅 기법을 제안한다. 또한 실험을 통해 제안 기법이 네트워크 운영의 신뢰도를 향상 시킬 수 있을 뿐만 아니라, 에너지 소모량과 오류 복구 지연 시간 측면에서 제안 기법을 적용하지 않았을 때보다 좋은 성능을 보인다는 것을 검증한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권12호
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• pp.4725-4747
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• 2020

Software defined networking (SDN) is considered to be one of the most promising paradigms in the future. To solve the scalability and performance problem that a single and centralized controller suffers from, the distributed multi-controller architecture is adopted, thus forms multi-domain SDN. In a multi-domain SDN network, it is of great importance to ensure a reliable control plane. In this paper, we focus on the reliability problem of multi-domain SDN against controller failure from perspectives of backup controller deployment and controller replication. We firstly propose a placement algorithm for backup controllers, which considers both the reliability and the cost factors. Then a controller replication mechanism based on shared data storage is proposed to solve the inconsistency between the active and standby controllers. We also propose a shared data storage layout method that considers both reliability and performance. Besides, a fault recovery and repair process is designed based on the controller backup and shared data storage mechanism. Simulations show that our approach can recover and repair controller failure. Evaluation results also show that the proposed backup controller placement approach is more effective than other methods.

• Nuclear Engineering and Technology
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• 제53권10호
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• pp.3236-3246
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• 2021

Lessons learned from the Fukushima Daiichi nuclear power plant accident directed that multiple failures should be considered more seriously rather than single failure in the licensing bases and safety cases because attempts to take accident management measures could be unsuccessful under the high radiation environment aggravated by multiple failures, such as complete loss of electric power, uncontrollable loss of coolant inventory, failure of essential safety function recovery. In the case of the complete loss of electric power called station blackout (SBO), if there is no mitigation action for recovering safety functions, the reactor core would be overheated, and severe fuel damage could be anticipated due to the failure of the active heat sink. In such a transient condition at CANDU-6 plants, the seal failure of the primary heat transport (PHT) pumps can facilitate a consequent increase in the fuel sheath temperature and eventually lead to degradation of the fuel integrity. Therefore, it is necessary to specify the regulatory guidelines for multiple failures on a licensing basis so that licensees should prepare the accident management measures to prevent or mitigate accident conditions. In order to explore the efficiency of implementing accident management strategies for CANDU-6 plants, this study proposed a realistic accident analysis approach on the SBO transient with multiple-failure sequences such as seal failure of PHT pumps without operator's recovery actions. In this regard, a comparative study for two PHT pump seal failure modes with and without coolant seal leakage was conducted using a best-estimate code to precisely investigate the behaviors of thermal-hydraulic parameters during transient conditions. Moreover, a sensitivity analysis for different PHT pump seal leakage rates was also carried out to examine the effect of leakage rate on the system responses. This study is expected to provide the technical bases to the accident management strategy for unmitigated transient conditions with multiple failures.

• 한국경영과학회지
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• 제35권3호
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• pp.1-24
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• 2010

As the Internet is explosively growing and the market is rapidly globalized, many entrepreneurs have been given an impetus to take on the function of the intermediation between providers and customers. Organizations performing the mediating roles in the cyberspace are termed 'cybermediary' and often called 'Openmarket' as a kind of transactional cybermediary in Korea. Despite sustainable growth of Openmarket, customer complaints and damages are increasing because of absence of recovery standards after a service failure. Therefore, it is important that a service provider converts dissatisfied customers to advocates for the growth of the Openmarket. This study aims to examine the role of recovery of the service failures for the Openmarket by proposing a relationship between complaint handling and continuance based on the equity theory. From the empirical results, we found that interactional equity had significant effects on both overall service satisfaction and recovery satisfaction, while procedural equity significantly influenced only recovery satisfaction. Recovery satisfaction also had an impact on overall service satisfaction and each satisfaction factor was positively related to continuance intention.

• 한국통신학회논문지
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• 제28권9B호
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• pp.793-805
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• 2003

헤더 정보와 버스트를 분리하여 전송되는 광 버스트 스위칭 망에서 장애의 발생은 심각한 서비스 품질 저하를 초래할 수 있으므로 신속한 복구 대책을 수립하여 망에서 발생하는 장애의 영향을 최소화하여야 한다. 본 논문에서는 먼저 기존에 제안된 복구 기법을 광 버스트 스위칭 망에 적용하여 각 링크의 장애에 따른 망 이용률 분석 및 버스트 손실률 등을 비교 평가하였다. 이에 대한 격과를 고려하여 망 구성 형태와 장애 링크의 위치를 고려한 ASPR (Area border router Sub-Path Restoration) 기법을 제안하였다. 제안된 기법은 장애 복구 지연 시간과 파장 변환기의 사용 효율성 관점에서 좋은 성능을 보이며 버스트 손실률, 망 자원 이용률, 그리고 버스트 처리율 관점에서 다른 기법과 비교 평가하였다.

• Journal of Communications and Networks
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• 제16권5호
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• pp.534-547
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• 2014

Large-scale failures resulting from natural disasters or intentional attacks are now causing serious concerns for communication network infrastructure, as the impact of large-scale network connection disruptions may cause significant costs for service providers and subscribers. In this paper, we propose a new framework for the analysis and prevention of network service disruptions in large-scale failure scenarios. We build dynamic deterministic and probabilistic models to capture the impact of regional failures as they evolve with time. A probabilistic failure model is proposed based on wave energy behaviour. Then, we develop a novel approach for preventive protection of the network in such probabilistic large-scale failure scenarios. We show that our method significantly improves uninterrupted delivery of data in the network and reduces service disruption times in large-scale regional failure scenarios.

• 지식경영연구
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• 제11권3호
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• pp.59-76
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• 2010

The knowledge of customer in healthcare service industry is widely accepted as one of the key information for the customers' satisfaction. Previous studies on the customer knowledge about service recovery showed that service providers are having difficulties with standardizing interaction with customer, This study investigated the attribution according to the failure in providing medical services and customer's participation as preceding variable of attribution. A survey was carried out targeting an obesity clinic having high participating rate from May 10 to May 28, 2010. The research results revealed that from whom the responsibility of the service failure originated between the patients and the medical institutions depending on the extent of the patients involvement in service process.

• 서비스연구
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• 제9권4호
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• pp.97-114
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• 2019

관여도가 높은 서비스 산업 분야에서 소비자가 지각하는 관계 품질과 서비스 실패의 복구 수준은 서비스 제공자의 이미지와 매출액에 직접적인 영향을 미치는 중요한 요인이다. 특히 성공적인 관계마케팅 전략의 실행과 서비스 실패에 대한 효과적인 복구는 맞춤형 서비스를 기대하는 고객들에게 더욱 많은 만족을 제공하며 기업과 소비자와의 관계를 강화시킨다. 본 연구는 이러한 선행연구들 기반으로, 서비스 실패의 심각성을 관계마케팅과 귀인이론의 관점에서 접근하여 서비스 복구 기대와 구전에 영향을 미치는 변수간의 인과관계를 규명하고자 진행되었다. 실증분석을 위하여 헤어살롱 이용 고객 360명을 대상으로 서비스 실패상황이라는 시나리오를 제시하여 설문조사를 실시한 후에, 불성실한 응답을 제외한 총 333부의 설문지를 최종 분석에 사용하였다. 구조방정식 모형을 이용하여 가설을 검정하였고, 그 결과는 다음과 같다. 첫째, 소비자가 서비스 실패의 심각성을 크게 지각할수록 관계 품질은 나빠진다는 가설이 규명되었다. 둘째, 소비자가 서비스 제공자와 좋은 관계를 유지할수록 서비스 실패의 원인을 일시적이고 통제 불가능한 것이라고 간주한다는 사실도 확인하였다. 셋째, 소비자가 서비스 실패 상황을 일시적인 것으로 지각할수록 서비스 복구에 대한 기대 수준도 높아질 것이라는 가설이 지지되었다. 넷째, 소비자는 서비스 제공자와 관계가 좋을수록 높은 서비스 복구 수준을 기대하며, 동시에 서비스 제공자에 대하여 긍정적인 구전을 할 가능성이 높아진다는 사실이 규명되었다. 본 연구의 이러한 결과는, 서비스 기업의 고객 지향적 비즈니스 모델 개발에 실무적인 도움을 줄 수 있으며 고관여 분야의 서비스 마케팅 연구를 위한 새로운 방향을 제시하였다는 점에서 학문적 의의를 찾을 수 있다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.187-194
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• 2002

Bridge dynamic behaviors and the failure of the foundation are examined in this study under seismic excitations including the local scour effect. The simplified mechanical model, which can consider the effect of various influence elements, is proposed to simulate the bridge motions. The scour depths around the foundations are estimated by the CSU equation recommended by the HEC-18 and the local scour effect upon global bridge motions is then considered by applying various foundation stiffness based upon the reduced embedded depths. From the simulation results, it is found that seismic responses of a bridge with the same scour depth for both foundations increase due to the local scour effect. The bridge scour is found to be significant under weak and moderate seismic intensity. The recovery durations of the foundation stiffness after local scour are found to be critical in the estimation of the probability of foundation failure under earthquakes. Therefore, the safety of the whole bridge system should be conducted with the consideration of the scour effect upon the foundations and the recovery duration of stiffness should be determined rationally.

• 한국수정란이식학회지
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• 제17권3호
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• pp.235-238
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• 2002

The present study was undertaken to find out possibilities for superovulation and recovery of freezable/transferable embryo from repeat breeding crossbred cows. For this study a total of 10 Holstein crossbred cows having history of failure of conception even after more than 4~5inseminations were taken and superovulated using Folltropin-V at 100 to 140% dose schedule. The results indicated that out of 10 donors, 8 responded to superovulatory treatment and yielding a total of 94 embryos, out of which 45 were of transferable/freezable quality. The mean ovulations and mean transferable embryos were 11.5$\pm$2.91 and 4.5$\pm$1.66, respectively. These observations suggests that the repeat breeding cows having conception failure after several artificial inseminations can be used as donors for production of embryos and calves through embryo transfer technology.