• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.868-871
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• 2014

오늘날 한국에서는 급성 심근경색증으로 인한 사망률이 높은 상태로, 발병 시에 치료까지 신속한 의사결정이 요구되는 위중한 질병이기 때문에, 한국인에게 맞는 급성 심근경색증 연구가 매우 중요 하다. 본 연구는 한국인 급성 심근경색증 등록 데이터를 이용해 기계 학습 방법의 한 종류인 나이브 베이지안 방법을 이용해 급성 심근경색증 환자의 예후를 예측하고자, 의료 데이터의 특성에 따른 데이터 변환 방법을 제안한다. 타겟 클래스에서 보다 중요한 의미를 가진 death 값에 대해 각 값을, nominal value, numeric value, 결측치로 구분한 방식에 따라, 확률을 계산해 변환한다. 실험 결과를 통해 결측치를 피처마다 존재하는 값들의 평균을 낸 값으로 대입하였을 때 가장 좋은 성능임을 알 수 있었는데, 기존의 방법에 비해 precision=5.4%, recall=7.0%의 성능이 향상되었다. 따라서 제안한 방법은 나이브 베이지안 방법의 예측 성능 향상에 기여하였다고 판단된다. 이후 적용했던 데이터 변환 방법을 여러 가지 기계 학습 방법에서 판단해보고, 다른 타겟 클래스에도 시험해보고자 한다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.5
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• pp.921-927
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• 1989

One of the most important problems in recent life prediction is to introduce the degradation effects into life prediction procedure. In the present paper, the effect of the material degradation on the fatigue surface crack growth and fatigue life prediction in a 2 1/4 Cr-1Mo steel were investigated. The 2 1/4 Cr-1Mo steel has been used in a plant having operated for over 60000hours and subjected to material degradation due to temper-embitterment. A Monte-Carlo simulation was made on the basis of the data obtained in the experiment in order to determine the P-S-N diagrams of surface crack growth for the degraded and recovered steels.

• Journal of the Korean Geosynthetics Society
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• v.17 no.4
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• pp.103-108
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• 2018

The fragility curves for CFRD dams are derived in this study for probabilistic damage estimation as a function of a ground motion intensity. The dam crest settlement, which is a widely used damage index, is used for minor, moderate, and extensive damage states. The settlement is calculated from nonlinear dynamic numerical simulations. The accuracy of the numerical model is validated through comparison with a centrifuge test. The fragility curve is represented as a log normal distribution function and presented as a function of the peak ground acceleration. The fragility curves developed in this study can be utilized for real time assessment of the damage of dams.

• Journal of Aerospace System Engineering
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• v.15 no.1
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• pp.47-55
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• 2021

When an abnormal landing occurs, aircraft structures should be designed to guarantee occupants survivability without preventing egress. To find out fire root causes at crash, lots of fixed aircraft crash tests were conducted. Appropriate crash load factors were established with the comprehension of structural behavior based on dynamic analysis and investigation of human tolerance. Cargo restraint criteria were set up considering passengers safety and operational cost while analyzing past cargo aircraft accident data using a probabilistic approach. Reviewing results of past crash tests, current crash landing load factor was appreciated physically, medically, and economically.

• Journal of Creative Information Culture
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• v.5 no.2
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• pp.145-156
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• 2019

In this study, we have developed and evaluated an information extracting module based on the named entity recognition technique. For the given purpose in this paper, the module was designed to apply to the problem dealing with extraction of postal address information from arbitrary documents without any prior knowledge on the document layout. From the perspective of information technique practice, our approach can be said as a probabilistic n-gram (bi- or tri-gram) method which is a generalized technique compared with a uni-gram based keyword matching. It is the main difference between our approach and the conventional methods adopted in natural language processing that applying sentence detection, tokenization, and POS tagging recursively rather than applying the models sequentially. The test results with approximately two thousands documents are presented at this paper.

• The Transactions of the Korea Information Processing Society
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• v.13 no.5
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• pp.227-235
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• 2024

Since nuclear power plants (NPPs) increasingly employ digital I&C systems, reliability evaluation for NPP software has become crucial for NPP probabilistic risk assessment. Several methods for estimating software reliability have been proposed, but there is no available tool support for those methods. To support NPP software manufacturers, we propose a reliability measurement tool for NPP software. We designed our tool to provide reliability estimation depending on available qualitative and quantitative information that users can offer. We applied the proposed tool to an industrial reactor protection system to evaluate the functionality of this tool. This tool can considerably facilitate the reliability assessment of NPP software.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.187-194
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• 2020

The T&E (Test and Evaluation) results were applied for a judgment basis to decide the developmental process of system engineering for efficient weapon system R&D (Research and Development). During the OT&E (Operational Test and Evaluation) and DT&E (Development Test and Evaluation), an environmental test is essential for weapon system development owing to their highly exposed operational conditions. Based on the MIL-STD-810, MIL-HDBK-310, and AECTP 200, the ROK armed forces recommended operating temperatures for the ROK weapon system and applied this to the DT&E and OT&E. This study examined the compatibility of Korean temperature guidelines for stockpile material considering recent climate change. Moreover, this study analyzed the data from hourly measured temperatures on 101 observatories during 60 years, from 1960 to 2020, and percentage (0.5%, 1%, 5%, and 10%) and the 𝜎 (3𝜎, 2𝜎, and 1𝜎) frequency of occurrence on rigorous hot (August) and cold (January) periods, respectively. The results indicate that the highest temperature was 41℃, and the 0.5% frequency of occurrence was 37.0℃. In the case of the cold period, the lowest temperature was -32.6℃ and the 0.5% frequency of occurrence was -21.1℃. By considering the previously recommended operating temperature range for a general ground system, -30 ~ 40℃, regional operation probability is recognized 99.999%. Despite the recent abnormal climate change from global warming, the Korean temperature guidelines are compatible with the stockpile material environmental test.

• Tunnel and Underground Space
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• v.22 no.2
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• pp.106-119
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• 2012

Roughness of rock joint has generally been characterized based upon geometrical aspects of a two-dimensional surface profile. The appropriate description of joint roughness, however, should consider the features of roughness mobilization at contact areas under normal and shear loads. In this study, direct shear tests were conducted on the replicas of tensile fractured gneiss joints and the influence of the shear direction on the shear behavior and effective roughness was examined. In this procedure, a joint surface was represented as a group of triangular planes, and the steepness of each plane was characterized using the concepts of the active and inactive micro-slope angles. The contact areas at peak strength which were estimated by a numerical method showed that the locations of the contact areas were mainly dependent on the distribution of the micro-slope angle and the shear behavior of joint was dominated by only the fractions with active micro-slope angles. Therefore, a three-dimensional coefficient for the quantification of rock joint roughness is proposed based on the distribution of active micro-slope angle: active roughness coefficient, $C_r$. Comparison of the active roughness coefficient and the peak shear strength obtained from the experiment suggests that the active roughness coefficient is the effective parameter to quantify the surface roughness and estimate the shear behavior of rock joint.

• Tunnel and Underground Space
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• v.16 no.4 s.63
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• pp.281-287
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• 2006

Intake of groundwater by tunneling in a mountainous area mostly results from groundwater flow through fractured parts of total rock mass. For reasonable analysis of this phenomenon the representative joint groups 1, 2, and 3 have been selected by previous investigations, geological/geophysical field tests and boring works. Three dimensional fractures were generated by the FracMan and MAFIC which is a three dimensional finite element model has been used to analyse a groundwater flow through fractured media. Monte Carlo simulation was applied to reduce the uncertainty of this study. The numerical results showed that the average and deviation of amounts of groundwater intaked into tunnel per unit length were $5.40{\times}10^{-1}$ and $3.04{\times}10^{-1}m^3/min/km$. It is concluded that tunnel would be stable on impact of groundwater environment by tunneling because of the lower value than $2.00{\sim}3.00m^3/min/km$ as previous and present standard on the application of tunnel construction.

• 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.