• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.55-61
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• 2007

Recently simulation model becomes an essential tool for analysis and design of a system but it is often expensive and time consuming as it becomes complicate to achieve reliable results. Therefore, high-fidelity simulation model needs to be replaced by an approximate model, the so-called metamodel. Metamodeling techniques include 3 components of sampling, metamodel and validation. Cross-validation approach has been proposed to provide sequnatially new sample point based on cross-validation error but it is very expensive because cross-validation must be evaluated at each stage. To enhance the cross-validation of metamodel, sequential sampling method using candidate points and representative cross-validation is proposed in this paper. The candidate and representative cross-validation approach of sequential sampling is illustrated for two-dimensional domain. To verify the performance of the suggested sampling technique, we compare the accuracy of the metamodels for various mathematical functions with that obtained by conventional sequential sampling strategies such as maximum distance, mean squared error, and maximum entropy sequential samplings. Through this research we team that the proposed approach is computationally inexpensive and provides good prediction performance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.1
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• pp.59-67
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• 2003

PMI(Privilege Management Infrastructure) certificates as well as Public-Key certificates must be validated before being used. Validation for a PMI certificate requires PMI certificate path validation, and PKC(Public-Key Certificate) path validations for each entity in the PMI certificate path. This validation work is quite complex and burdened to PMI certificate verifiers. Therefore, this paper suggests a delegated PMI certificate validation that uses specialized validation server, and defines a validation protocol which is used between validation server and client.

• Geomechanics and Engineering
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• v.28 no.5
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• pp.437-454
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• 2022

The hydro-mechanical (HM) two-way sequential coupling in the TOUGH2-FLAC3D linking algorithm is validated completely and successfully in both M to H and H to M directions, which are initiated by mechanical surface loading for geomechanical validation and hydrological groundwater pumping for hydrogeological validation, respectively. For such complete and successful validation, a TOUGH2-FLAC3D linked numerical model is developed first by adopting the TOUGH2-FLAC3D linking algorithm, which uses the two-way (fixed-stress split) sequential coupling scheme and the implicit backward time stepping method. Two geomechanical and two hydrogeological validation problems are then simulated using the linked numerical model together with basic validation strategies and prerequisites. The second geomechanical and second hydrogeological validation problems are also associated with the Mandel effect and the Noordbergum and Rhade effects, respectively, which are three phenomenally well-known but numerically challenging HM effects. Finally, sequentially coupled numerical solutions are compared with either analytical solutions (verification) or fully coupled numerical solutions (benchmarking). In all the four validation problems, they show almost perfect to extremely or very good agreement. In addition, the second geomechanical validation problem clearly displays the Mandel effect and suggests a proper or minimum geometrical ratio of the height to the width for the rectangular domain to maximize agreement between the numerical and analytical solutions. In the meantime, the second hydrogeological validation problem clearly displays the Noordbergum and Rhade effects and implies that the HM two-way sequential coupling scheme used in the linked numerical model is as rigorous as the HM two-way full coupling scheme used in a fully coupled numerical model.

• Journal of Korea Multimedia Society
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• v.24 no.10
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• pp.1403-1413
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• 2021

In this paper, we investigate automated data validation techniques for artificial intelligence training, and also disclose open-source frameworks, such as Google's TensorFlow Data Validation (TFDV), that support automated data validation in the AI model development process. We also introduce an experimental study using public data sets to demonstrate the effectiveness of the open-source data validation framework. In particular, we presents experimental results of the data validation functions for schema testing and discuss the limitations of the current open-source frameworks for semantic data. Last, we introduce the latest studies for the semantic data validation using machine learning techniques.

• International Journal of Computer Science & Network Security
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• v.21 no.12spc
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• pp.549-555
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• 2021

Machine Learning(ML) splits data into 3 parts, which are usually 60% for training, 20% for validation, and 20% for testing. It just splits quantitatively instead of selecting each set of data by a criterion, which is very important concept for the adequacy of test data. ML measures a model's accuracy by applying a set of validation data, and revises the model until the validation accuracy reaches on a certain level. After the validation process, the complete model is tested with the set of test data, which are not seen by the model yet. If the set of test data covers the model's attributes well, the test accuracy will be close to the validation accuracy of the model. To make sure that ML's set of test data works adequately, we design an experiment and see if the test accuracy of model is always close to its validation adequacy as expected. The experiment builds 100 different SVM models for each of six data sets published in UCI ML repository. From the test accuracy and its validation accuracy of 600 cases, we find some unexpected cases, where the test accuracy is very different from its validation accuracy. Consequently, it is not always true that ML's set of test data is adequate to assure a model's quality.

• Journal of the Korean Data and Information Science Society
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• v.23 no.4
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• pp.765-775
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• 2012

The cross-validation is a popular method to select bandwidth in all types of kernel estimation. The maximum likelihood cross-validation, the least squares cross-validation and biased cross-validation have been proposed for bandwidth selection in kernel density estimation. In the case that the probability density function has a discontinuity point, Huh (2012) proposed a method of bandwidth selection using the maximum likelihood cross-validation. In this paper, two forms of cross-validation with the one-sided kernel function are proposed for bandwidth selection to estimate the location and jump size of the discontinuity point of density. These methods are motivated by the least squares cross-validation and the biased cross-validation. By simulated examples, the finite sample performances of two proposed methods with the one of Huh (2012) are compared.

• Toxicological Research
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• v.25 no.1
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• pp.1-8
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• 2009

Validation specifies and coordinates all relevant activities to ensure compliance with good laboratory practices (GLP) according to suitable international standards. This includes validation activities of past, present and future for the best possible actions to ensure the integrity of non-clinical laboratory data. Recently, validation has become increasingly important, not only in good manufacturing practice (GMP) institutions but also in GLP facilities. In accordance with the guideline for GLP regulations, all equipments used to generate, measure, or assess data should undergo validation to ensure that this equipment is of appropriate design and capacity and that it will consistently function as intended. Therefore, the implantation of validation processes is considered to be an essential step in a global institution. This review describes the procedures and documentations required for validation of GLP. It introduces basic elements such as the validation master plan, risk assessment, gap analysis, design qualification, installation qualification, operational qualification, performance qualification, calibration, traceability, and revalidation.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.2 s.17
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• pp.57-64
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• 2004

A Requirement statement validation process is suggested which was established and applied to the rolling stock development project of the Korean Railway Research Institute. The validation process includes team organization, selection of validation criteria, development of validation template, education of team members, validation, construction of database and management of requirement change. Many defects in the specification of requirement were found to be associated with the problem of non-uniqueness, describing solution instead of problem, ambiguity and redundancy. This paper described detailed activities at each step of the validation process and lessons learned from these activities.

• The KIPS Transactions:PartC
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• v.10C no.4
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• pp.433-440
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• 2003

According as the real economic activities are carried out in the cyber world and the identity problem of a trade counterpart emerges, digital signature has been diffused. Due to the weakness for real-time validation using the validation method of digital signature, Certificate Revocation List, On-line Certificate Status Protocol was introduced. In this case, every transaction workload requested to verify digital signature is concentrated of a validation server node. Currently this method has been utilized on domestic financial transactions, but sooner or later the limitation will be revealed. In this paper, the validation method will be introduced which not only it can guarantee real-time validation but also the requesting node of certificate validation can maintain real-time certificate status information. This method makes the revocation management node update the certificate status information in real-time to the validation node while revoking certificate. The characteristic of this method is that the revocation management node should memorize the validation nodes which a certificate holder uses. If a certificate holder connects a validation node for the first time, the validation node should request its certificate status information to the above revocation management node and the revocation management node memorizes the validation node at the time. After that, the revocation management node inform the revocation information in real-time to all the validation node registered when a request of revocation happens. The benefits of this method are the fact that we can reduce the validation time because the certificate validation can be completed at the validation node and that we can avoid the concentration of requesting certificate status information to a revocation node.

• Journal of Internet Computing and Services
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• v.4 no.4
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• pp.53-64
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• 2003

To perform the certificate validation on the user-side application induces the very considerable overhead on the user-side system because of the complex and time-consuming characteristic of the validation processing. Most of the time spend for performing the validation processing is required for the digital signature verification, since the verification accompanies with the cryptographic calculation over each certificate on the certificate path. In this paper, we propose a new certificate validation scheme using DSVP(Delegated Signature Validation Protocol) which can reduce the overhead for the user-side certificate validation processing. It is achieved by delegating the digital signature verification to CAs of the PKI domain. As the proposed DSVP is the protocol performed between a user and CAs, it is applied to the hierarchical PKI efficiently and used for delegating the digital signature verification reliably and safely, our proposed scheme can not only reduces the overhead for the validation processing by decreasing the cryptographic calculation but also improves the utilization of CAs by employing them to the validation processing.