• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.212-221
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• 2022

In this paper, the evaluation procedure applying the limit state design method is studied to be consistent with the newly issued bridge design code in Korea. The live load factor for evaluation is proposed by calibrating for the target reliability index through reliability analysis. Using the actual bridge information collected for the representative bridge types in Korea, the load effects of the design live loads for the previous and current design codes are calculated and compared. The live load factor is calibrated through reliability analysis using the minimum required strength which equals to the load effect obtained for the example bridge. Bridge evaluation is performed by applying the live load factors for the evaluation level as well as design level. The load rating result is generally increased by applying the limit state design method compared to the previous design method and applying the proposed load factor for lowered target reliability index further increased the rating result.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.497-500
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• 2008

In order to prevent deterioration of reinforced concrete structures exposed to marine environment, performance based durability design than the design by conventional deemed-to-satisfy rule should be concerned. For example, even though chloride threshold level, which is a major parameter for durability design, is defined as a 1.2 $kg/m^3$ in the Korean concrete specification, it shows that the chloride threshold level leads to over design in its real application so that realistic value should be determined for the performance design. In this paper, not only the probabilistic properties of chloride threshold level obtained from published data are taken into account, but also the experimental results of the probabilistic properties using surface chloride content, diffusion coefficient, cover depth are considered in the assessment utilizing the concept of performance based durability design. In computation, the Monte Carlo Simulation (MCS) is used to perform an assessment due to chloride attack for a target submerged tunnel box. This study found that the specification on current chloride threshold level should be modified for more rational and accurate assessment and design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.575-584
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• 2014

In this study, the NREL 5 MW wind turbine tower model was optimized according to the multi-body dynamics and reliability-based design. The mathematical model was defined as a link-joint system including dynamic characteristics derived from Timoshenko's beam theory. For the optimization problem, the sensitivities to variations in the tower thicknesses and inner and outer diameters were acquired and arranged in terms of safety and efficiency according to bending stress and buckling standards. An optimal design was calculated with the advanced first-order second moment method and used to define a finite element model for validation. The finite element model was simulated by static analysis. The relationship between the multi-body dynamic and finite element method throughout the process was investigated, and the optimal model, which had high endurance despite its low mass, was determined.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.453-454
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• 2011

에너지 플랜트, 화학공장 등 대형 기계설비의 복잡도 증가는 그에 따른 위험요소 복잡도를 증가시키고 있다. 대형 기계설비에 대한 위험 관리와 시스템 신뢰도 향상을 위해서는 위험도 기반의 안전 설계/해석, 상태 감시 및 진단을 이용한 설비 모니터링, 인적 신뢰도 향상이 요구되며 설계 단계에서부터 운영 및 유지보수 단계까지의 시스템 생애주기 전반에 걸친 지속적인 활동을 필요로 한다. 인적 신뢰도를 향상시키기 위해서는 설비 운영자가 응급 또는 이상상황에 대처할 수 있는 능력 즉, 안전사고 대응 능력 확보가 필수적이다. 대상 설비에 대한 실제 훈련은 시간, 비용, 훈련자의 안전 확보가 어렵고 반복적인 훈련 및 평가가 어렵기 때문에 가상 환경을 이용한 안전대응 훈련 플랫폼을 설계하였다. 훈련자에게 몰입형 가상 환경을 제공하기 위하여 가상현실 및 안전사고 시뮬레이션 기술을 이용하였으며 이를 통하여 훈련자의 안전을 유지하면서 안전대응 능력을 향상시킬 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11B
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• pp.730-735
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• 2005

While the E-mail is a important way of fast communication in these days. it is real that the E-mail is often misused as a commercial advertisement method and creates many social problems. Even though various filtering techniques for blocking spam mails have been developed, reliability of mail systems is decreased by misreading normal mails as spam mails, i.e. false-positive errors. In this paper, the SMBC(Spam Mail Blocking Center) platform employing spam mail recovery method based on privacy information is proposed and designed. The SMBC is designed in frame layer based on spam blocking system of proxy sewer and can be physically implemented in various topology so that flexible development with layered module is possible. Using privacy information makes the proposed SMBC platform minimize processing load and false-positive error rates so that it can improve mail system reliabilities.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.382-384
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• 2003

인터넷 멀티캐스트 서비스는 네트워크 자원의 효율적 사용이라는 장점과 15년 이상의 연구, 개발에도 불구하고 아직 보편화 되지 못하고 있다. 이는 멀티캐스트 서비스가 망에서 지원이 잘 되지 않고 있고. 멀티캐스트 망 관리의 어려움. Killer Application 부재 등 많은 문제점이 있고, 멀티캐스트 서비스의 신뢰성 보장이 되지 않고 있다는 것도 하나의 문제점 이라고 할 수 있다. 본 논문에서는 인터넷 멀티캐스트 서비스의 신뢰성 보장을 위한 방법으로 기존에 발표된 트리기반의 프로토콜인 RMTP (Reliable Multicast Transport Protocol)[1]. [2]의 단점을 보완하여 신뢰성 있는 멀티캐스트 전송을 위한 방법을 제안하고자 한다.

• Journal of Science Education
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• v.47 no.2
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• pp.211-224
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• 2023

The purpose of this study is to suggest how to investigate the reliability of the assessment, which consists of items generated by automatic item generation using empirical example data. To achieve this, we analyzed the illustrative assessment data by applying the multivariate generalizability theory, which can reflect the design of responding to different items for each student and multiple error sources in the assessment score. The result of the G-study showed that, in most designs, the student effect corresponding to the true score of the classical test theory was relatively large after residual effects. In addition, in the design where the content domain was fixed, the ranking of students did not change depending on the item types or items. Similarly, in the design where the item format was fixed, the difficulty showed little variation depending on the content domains. The result of the D-study indicated that the original assessment data achieved a sufficient level of reliability. It was also found that higher reliability than the original assessment data could be obtained by reducing the number of items in the content domains of operation, geometry, and probability and statistics, or by assigning higher weights to the domains of letters and formulas, and function. The efficient measurement conditions presented in this study are limited to the illustrative assessment data. However, the method applied in this study can be utilized to determine the reliability and to find efficient measurement conditions for the various assessment situations using automatic item generation based on measurement traits.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.11a
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• pp.651-654
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• 2020

유튜브 등의 1인 미디어 플랫폼 열풍과 반대로, 이에 대한 엄격한 방송 규약은 존재하지 않아 생기는 여러 사회적 문제가 대두되고 있다. 이러한 1인 미디어 시청자는 원하는 정보를 찾기 위해 영상 제공자가 제공하는 정보에만 의존하여 영상을 선택하고 내용을 확인하여야 한다. 그 결과 의도한 주제와 맞지 않은 영상을 시청하게 되는 비효율성을 해결하기 위해, 본 연구에서는 용어 신뢰도 기반 유튜브 영상 필터링 웹 서비스(YouChoose)를 제안한다. YouChoose는 유튜브 리뷰 영상의 음성을 자연어 처리 기법을 이용하여 사전 처리하고 신뢰도를 도출해 사용자에게 제공함으로써 검색 시 의도와 일치하는 영상을 직접 시청 전에 추천 받을 수 있도록 한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.2
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• pp.217-225
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• 2010

Most of the steel bridges in Korea are being currently designed by the allowable stress design method that uses the conventional deterministic factors of safety. However the limit state design based on the concept of probability, statistics and reliability engineering is becoming very popular as a global standard deign method, leading the rational and economic bridge design. As part of the fundamental research to establish the load and resistance factor design(LRFD) of steel bridges considering domestic environmental conditions and regional characteristics, an experimental design is conducted by applying AASHTO-LRFD specification especially to a steel closed-box girder, which occupies relatively a large portion of steel bridges in Korea. Throughout the experimental design according to various sectional changes, some of the issues to be considered in the LRFD design of a composite steel closed-box girder bridge are examined. In this process, an Excel-based design verification program is developed for easy computation and prevention of errors. Quantitative reliability levels of the bridge sections designed by LRFD are also estimated using a reliability analysis method, and compared with the target reliability indexes applied in the LRFD design to verify the validity of the procedure and methodology used in this study.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.147-157
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• 2011

As a background study to apply the reliability-based resistance factors to the domestic concrete bridge design code, a comparative study is conducted for the design results and the reliability indexes obtained by adopting different resistance factor formats to yield the design strength of concrete structures. The design results which are calculated by applying the section resistance factors of the current domestic design code and the material resistance factors of Eurocode are compared for the concrete beam bridge. The reliability index is calculated by considering the uncertainties involved in material, dimension and strength equation during the design procedure to get the strength of concrete structure. Also, the sensitivity analysis is performed to figure out which design variables have great impact on the reliability index. The resistance factors of the current domestic bridge design code, AASHTO LRFD and Eurocode are applied to the bridge design for flexure and shear strength and the results show that the resistance factors of the domestic code give the largest reliability indexes. It is observed that the probabilistic distribution of the live load makes difference for the reliability index and the yield strength of reinforcing steel and the live load have great impact on the reliability of both flexural and shear strength of concrete beam through the sensitivity analysis.