• Proceedings of the Korea Information Processing Society Conference
• /
• 2005.11a
• /
• pp.991-994
• /
• 2005

통신기술의 급속한 발전으로 네트워크 환경이 광대역통합망으로 진화되어가고 있다. 이로 인해 개별 네트워크에서 운영되던 IT서비스들 또한 광대역통합망 환경에서 빠른 속도로 융합되고 있다. 하지만, 개별 네트워크에서 운영되던 기존의 IT서비스들이 광대역통합망에서 서로 융합되어 신규 IT 서비스를 생성하는 과정에서 보안요소가 적용되지 않을 경우에 신규 IT서비스의 안정성 및 신뢰성이 떨어질 수 있다. 이러한 문제점을 해결하기 위해서, 본 논문에서는 신규 IT 서비스의 기반구축 및 운영이전인 서비스에 대한 기획 및 설계시에 필수적인 보안대책 제시하여 서비스 운영이전에 보안대책을 적용할 수 있도록 함으로써, 신규 IT 서비스의 안정성과 신뢰성을 확보할 수 있는 방법으로 정보보호사전평가 모델을 설명한다.

• The Journal of Korean Association of Computer Education
• /
• v.11 no.1
• /
• pp.1-10
• /
• 2008

Web-based Assessment System is needed for Process-Oriented Evaluation to integrate instructions into evaluation frequently in Informatics Education, and considered usability for supporting teachers to test more conveniently. First of all, we analyzed usability of traditional Web-based Assessment System, and proposed PBA(Paper-Based Assessment) model by extracting usability features of paper-pencil assessment in off-line. The evaluation system based on the PBA model controls the whole processes of tests; before-test, under-test, after-test. Especially, the system readily can change the target class, and control access to the test page during each step. Thus we can get high credibility about the test results. Moreover, students can login to the paper easily by using their grade, class, number and name. Finally, we designed and implemented the Web-based Assessment System for Informatics education on the basis of PBA model; PAS(PBA-based Assessment System).

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.9
• /
• pp.1151-1158
• /
• 2013

Knowledge of the moisture sorption properties of a material is essential for optimal material development and analysis of the delamination failure caused by vapor pressure at the interlayer during the manufacturing process of integrated packaging devices. In this paper, both temperature dependent absorption and desorption properties according to temperature and humidity model are parameterized and the effects of water activities and temperature are discussed. The activation energy obtained from the parameterized diffusivity determines the acceleration factor for the equivalency of moisture sorption levels, which enables the effect of moisture diffusivity on the equivalent elapsed testing time required for evaluating the reliable life time to be estimated. The acceleration factor evaluated at the reliability testing standard of the flexible packaging module is exampled.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1035-1036
• /
• 2011

직구동방식 고속 솔레노이드 액추에이터는 자동차, 항공산업 등의 고정밀을 요구하는 산업시스템에 주요부품으로 사용되기 때문에 고신뢰성이 요구된다. 본 연구에서는 직구동방식 고속 솔레노이드 액추에이터의 신뢰성 평가를 위하여 2단계 품질기능전개를 통해 신뢰성시험항목을 결정하였다. 신뢰성평가 시험 중에서 가장 큰 우선도를 차지하는 수명시험에 대해 문헌, 연구계 및 현장실무자를 통한 무고장 수명시험 시간을 산출하였다. 또한 장기간 소요되는 무고장 수명시험 시간의 시간을 단축하기 위해 가속모델을 제안하고 실제 조건을 충족하는 가속수명 시험시간을 산출하였다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1998.05a
• /
• pp.869-875
• /
• 1998

원자력발전소 소외전원 상실 시 발전소를 안전하게 정지시키기 위한 비상디젤발전기의 신뢰성 평가는 계속적으로 수행되고 있는 연구과제 중 하나이다. 본 논문에서는 동적 시스템 모델링 툴을 사용하여 비상디젤발전기의 동적 신뢰도 평가를 위한 Markov모델을 구축하였다. 구축한 동적 신뢰도 모델을 이용하여 NUREG/CR-4810에서 제안한 분석방법의 모순점을 보완하여 Reg. Guide 1.108의 비상디젤발전기 가속시험주기 규정을 이용불능도 측면에서 검토하였다 또한 비상디젤발전기의 이용불능도는 기동실패확률 및 보수율과 기동실패 중 기동시 충격에 의한 고장 비율의 함수인 점을 고려하여 가속시험주기 규정을 따를 때 보수율과 기동시 충격에 의한 고장 비율이 이용불능도의 변화에 미치는 영향을 시뮬레이션하였다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.10
• /
• pp.931-940
• /
• 2017

This paper describes a predictive fault diagnosis algorithm for autonomous vehicles based on a kinematic model that uses a sliding mode observer. To ensure the safety of autonomous vehicles, reliable information about the environment and vehicle dynamic states is required. A predictive algorithm that can interactively diagnose longitudinal environment and vehicle acceleration information is proposed in this paper to evaluate the reliability of sensors. To design the diagnosis algorithm, a longitudinal kinematic model is used based on a sliding mode observer. The reliability of the fault diagnosis algorithm can be ensured because the sliding mode observer utilized can reconstruct the relative acceleration despite faulty signals in the longitudinal environment information. Actual data based performance evaluations are conducted with various fault conditions for a reasonable performance evaluation of the predictive fault diagnosis algorithm presented in this paper. The evaluation results show that the proposed diagnosis algorithm can reasonably diagnose the faults in the longitudinal environment and acceleration information for all fault conditions.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.949-952
• /
• 2008

화재안전 신뢰성이 확보된 고강도 콘크리트 구조물의 시장 공급을 위하여 GS건설에서는 2005년 부터 고강도 콘크리트 구조물의 강도 영역별 폭렬 저감 및 거동 안전성 평가와 수치해석 방법을 통한 경제적인 설계방법를 최종 연구목표로 하여 현재까지 콘크리트 재료의 열적 특성 확보와 구조부재 화재 특성 연구를 수행해 왔다. 강도발현, 시공성, 내화성능과 경제성에 대한 분석을 해외연구 기관에 의뢰하여 섬유혼입공법을 선정한 후 이에 대한 재료의 물리적 특성과 역학적 특성 실험결과를 바탕으로 고강도 콘크리트 구조부재의 내화성능을 예측 분석할 수 있도록 비열 모델, 열전도율모델, 압축강도 모델, 탄성계수 모델을 구축하였다. 또한 기둥과 보에 대한 내화실험을 실시하여 내화성능을 평가하였으며, 이에 대한 열적 해석을 병행하여 진행하였다.

• Journal of Aerospace System Engineering
• /
• v.18 no.1
• /
• pp.11-20
• /
• 2024

In the recent era of NewSpace, unlike high-reliability satellites of the past, low-reliability satellites are being developed and mass-produced at a lower cost to launch constellations satellites. To achieve cost-effective cluster satellite development, satellite users and developers need to assess the feasibility of maintaining mission performance over the expected lifespan when cluster satellites are launched. Plans for replacements due to random failures should also be established to maintain performance. This study proposed a method for assessing system reliability and availability to maintain mission performance and establish replacement strategies for Earth observation constellation satellites. In this study, a constellation reliability and availability model considering mission performance required for a satellite constellation, situations of satellite backup, and additional ground backups was established. The reliability model was structured based on the concept of a k-out-of-n system and the availability model used a Markov chain model. Based on the proposed reliability model, the minimum number of satellites required to meet mission requirements was defined and satellites needed in orbit during the required mission period to satisfy mission reliability were calculated. This research also analyzed the number of spare satellites in orbit and on the ground required to meet the desired availability during required service period through availability analysis.

• Journal of the Korean Society for Railway
• /
• v.12 no.4
• /
• pp.535-541
• /
• 2009

The reliability of control system composed of electronic parts has been studied by DoD since 1960, and has been undertaken mainly by Europe for railways. Especially in Korea, a study on reliability of signalling equipment has been taken since 2000, requiring reliability test for effective maintenance of old type signalling equipment which no longer has information on its past reliability. This study evaluates the reliability test in units of parts for old type signalling equipment; for instance, failure rate in units of parts, or failure data during operation; which was utilized without its consistent reliability monitoring and analysis data for over 20 years. Also, reliability change at this point in time has been estimated by using residual life span function, and a model which can evaluate the possibility of extended operation through stress acceleration test has been developed. This model will be utilized to establish future maintenance policy for train operating company's operation on old type signalling equipment.

• International Journal of Highway Engineering
• /
• v.12 no.2
• /
• pp.9-16
• /
• 2010

Roughness is the most important factor to maintain the road performance, and affects greatly on the design life in Jointed Plain Concrete pavements. Also, the factors the evaluate pavement‘s commonality is the three method such as functionality, safety and structural performance. In evaluating function of road, representative factors is the roughness, which has been used to determine maintenance time as key standard. As research for roughness is absence in pavement design. Applied roughness-model had a low-reliability in Korea. Therefore, it is needed to develop reliable model in road roughness. In this research, uniform specific is applied to distribute them after selecting the concrete pavements. Concrete pavement is divided by sections of 238. Total length of this sections has 281km and account for 16% of total road length in korean concrete pavements for selected sections. Considering the korean roughness-model, the evaluation of roughness is performed for the freezing index, average annual rainfall, condition for the base, the amount of traffic as well as spalling(%), cracking(%), age(year) at the selected section at the selected section. Also, additional sections is selected to evaluate various age which affects on the roughness. As a result of the analysis, it showed that spalling(%), cracking(%), age(year), and the condition of the base affected road roughness. When the correlation with the road roughness was analyzed, the reliable model for road roughness was proposed, and the ratio that can explain road roughness was R2-68.8% and P value-0 which is statistically meaningful.