• 해양환경안전학회지
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• 제1권1호
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• pp.95-106
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• 1995

The small-waterplane-area-twin-hull(SWATH) ship has been recognized as a promising high performance ship because of her superior seakeeping characteristics and large deck area for various operations compared to the conventional monohull ship. significant advances in analytical technics for the prediction of the ship motions, wave loads and structural responses, structural fatigue and its prediction, and hull vibration for ship motions, wave loads and structural responses, structural fatigue and its prediction, and hull vibration for SWATH ship have been much developed during the last twenty years. Based on these developments in technology an integrated computational procedures for prediction wave loads and structural responses can be used to get a accurate results. But the major problem of SWATH ship's structural design is the accurate prediction of structural responses by the maximum critical loads likely to be experienced during the life of SWATH. To get a easier and safer computational procedures and the analytical approach for determining the accurate structural responses, a case study has been presented through the project experienced.

• 터널과지하공간
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• 제4권1호
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• pp.63-76
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• 1994

This paper discusses contents of the existing design, the behaviours prediction on the strut and retaining wall around subsurfaces, and also evaluates the measured results in comparison with the management criterion during excavation period of ventilation shaft at Pusan-Subway 220. Field measurements showed that maximum displacement 23.74 mm at boundary site of multistratification and the weathered rock to be formed at 0.2~0.6 H of total excavating depth(H), 68 ton of maximum axial force and 4.4X102 kg/cm2 of stress on strut. The measured axial force exceeds prediction levels by up to 50 percent at the weathered soil & rock, and the others come under the category of their levels. The great gap of both field measurements and prediction on behaviour makes a difference of the site situation at the design stage and the practical working. This measured value is greatly safety in comparison with that of the safety criterion, but axial force at 4~5 strut of ventilation shaft l is higher than the prediction.

• 대한안전경영과학회지
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• 제7권1호
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• pp.199-210
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• 2005

Customer segmentation prediction has attracted a lot of research interests in previous literature, and recent studies have shown that artificial neural networks (ANN) method achieved better performance than traditional statistical ones. However, ANN approaches have suffered from difficulties with generalization, producing models that can overfit the data. This paper employs a relatively new machine learning technique, support vector machines (SVM), to the customer segmentation prediction problem in an attempt to provide a model with better explanatory power. To evaluate the prediction accuracy of SVM, we compare its performance with logistic regression analysis and ANN. The experiment results with real data of insurance company show that SVM superiors to them.

• 해양환경안전학회지
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• 제4권1호
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• pp.31-40
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• 1998

Through the combination of existing tidal prediction model and numerical tidal model, the efficient tidal prediction system was formulated and applied to the neighboring area of Pusan port. Because all tidal constituents for tidal prediction (69 tidal constituents are normally used) couldn't be considered due to the physical limits on computing process, some errors between the observed and predicted values were inevitably occurred. But it was confirmed that the computed values with maximum 10% of relative errors can be obtained if four major tidal constituents(M2, S2, K1, O1) are used. Thus, if other constituents than four major tidal constituents are additionally used, more accurate values will be obtained. Furthermore, if the database for harmonic constants in coastal waters is made in advance, using the numerical tidal model, prompt tidal prediction can be achieved at any time when it is required.

• 한국안전학회지
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• 제31권4호
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• pp.48-54
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• 2016

The prediction of various emissions from coal combustion is an important subject of researchers and engineers because of environmental consideration. Therefore, the development of the models for predicting pollutants very fast has received much attention from international research community, especially in the field of safety assessment. In this work, response surface method was introduced as a design of experiment, and the database for RSM was set with the numerical simulation of a drop tube furnace (DTF) to predict the spatial distribution of pollutant concentrations as well as final ones. The distribution of carbon dioxide in DTF was assumed to have Boltzman function, and the resulted function with parameters of a high $R^2$ value facilitates predicting an accurate distribution of $CO_2$. However, CO distribution had a difference near peak concentration when Gaussian function was introduced to simulate the CO distribution. It might be mainly due to the anti-symmetry of the CO concentration in DTF, and hence Extreme function was used to permit the asymmetry. The application of Extreme function enhanced the regression accuracy of parameters and the prediction was in a fairly good agreement with the new experiments. These results promise the wide use of statistical models for the quantitative safety assessment.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.4042-4051
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• 2021

In this work, we applied a multilevel modeling technique to estimate the diametral creep in the pressure tubes of Korean Canada Deuterium Uranium (CANDU) units. Data accumulated from in-service inspections were used to develop the model. To confirm the strength of the multilevel models, a 2-level multilevel model considering the relationship between channels for a CANDU unit was compared with existing linear models. The multilevel model exhibited a very robust prediction accuracy compared to the linear models with different data pooling methods. A 3-level multilevel model, which considered individual bundles, channels, and units, was also implemented. The influence of the channel installation direction was incorporated into the three-stage multilevel model. For channels that were previously measured, the developed 3-level multilevel model exhibited a very good predictive power, and the prediction interval was very narrow. However, for channels that had never been measured before, the prediction interval widened considerably. This model can be sufficiently improved by the accumulation of more data and can be applied to other CANDU units.

• 한국산업보건학회지
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• 제31권3호
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• pp.185-193
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• 2021

Objectives: Inhalation toxicity testing of chemical substances to identify carcinogenicity requires a long time and considerable cost, so the selection of test candidates is a very important aspect. This study was performed to determine optimal procedures for selecting carcinogenic inhalation toxicity test substances as conducted by the Occupational Safety and Health Research Institute (OSHRI). Methods: At the beginning, a database was constructed containing complex information such as usage amount, hazard, carcinogenicity prediction, and testability in order to select chemicals requiring carcinogenicity testing. Selection of test substances was carried out with priority given to usage, carcinogenicity, and testability. Results: Chemicals used in large quantities in industrial fields and strongly suspected of carcinogenicity were winnowed down to 12 substances, and these substances were scheduled for future testing by OSHRI. Conclusions: For the stable and reliable operation of carcinogenicity tests as conducted by OSHRI, this study standardized the procedures for selecting carcinogenicity test substances and suggested the introduction of various carcinogenicity prediction techniques.

• 한국산업융합학회 논문집
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• 제27권3호
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• pp.609-618
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• 2024

System reliability prediction in the development stage is increasingly crucial to reliability growth management to satisfy its target reliability, since modern system usually takes a form of complex composition and various complicated functions. In most cases of development stage, however, the information available for system reliability prediction is very limited, making it difficult to predict system reliability more precisely as in the production and operating stages. In this study, a system reliability prediction process is considered when the reliability-related information such as SIL (Safety Integrity Level) and MTTFd (Mean Time to Dangerous Failure) is available in the development stage. It is suggested that when the SIL or MTTFd of a system component is known and the field operational data of similar system is given, the reliability prediction could be performed using the scaling factor for the SIL or MTTFd value of the component based on the similar system's field operational data analysis. Predicting a system reliability is then adjusted with the conversion factor reflecting the temperature condition of the environment in which the system actually operates. Finally, the case of applying the proposed system reliability prediction process to a high performance mooring platform is dealt with.

• 대한기계학회논문집B
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• 제37권12호
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• pp.1175-1183
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• 2013

전산유체역학 소프트웨어의 일부 개발자 및 사용자는 최신 전산유체역학 소프트웨어가 최소한 단상 원자로 안전문제는 타당하게 해석할 수 있을 것으로 생각하지만 계산 결과에는 여전히 제한성 및 불확실도가 존재한다. 현재 한국원자력안전기술원에서는 규제관점에서 원자로 안전문제에 대한 상용 전산유체역학 소프트웨어의 성능평가를 수행하고 있다. 본 연구에서는 축소 APR+ 원자로 내부유동 해석시다공성 모델을 적용한 상용 전산유체역학 소프트웨어의 예측 성능을 평가하기 위해 ANSYS CFX R.14 및 FLUENT R.14 에 탑재된 수치모델을 이용하여 계산을 수행하였다. 결론적으로 전산유체역학 소프트웨어에 따라 축소 APR+ 원자로 내부유동 분포는 국부적으로 차이가 발생하였다. 비록 제한된 수의 측정치로 인해 상용 전산유체역학 소프트웨어간 예측성능을 평가하기에는 다소 한계가 있으나 CFX R.14 가 FLUENT R.14 에 비해 상대적으로 타당한 예측결과를 제시하였다. 한편 적용된 차분법의 차이로 인해 동일한 격자에 대해 FLUENT R.14 가 CFX R.14 에 비해 상대적으로 많은 계산 메모리를 필요로 하였다. 따라서 대용량 병렬 계산시 가용한 계산 자원에 적합한 전산유체역학 소프트웨어가 선정되어야 한다.

• 건설안전기술
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• 통권46호
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• pp.74-81
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• 2008