• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2933-2940
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• 2022

Approximations such as the delete-term approximation, rare event approximation, and minimal cutset upper bound (MCUB) need to be prudently applied for the quantification of a seismic probabilistic safety assessment (PSA) model. Important characteristics of seismic PSA models indicate that preserving the success branches in a primary seismic event tree is necessary. Based on the authors' experience in modeling and quantifying plant-level seismic PSA models, the effects of applying negate-down to the success branches in primary seismic event trees on the quantification results are summarized along with the following three insights gained: (1) there are two competing effects on the MCUB-based quantification results: one tending to increase and the other tending to decrease; (2) the binary decision diagram does not always provide exact quantification results; and (3) it is identified when the exact results will be obtained, and which combination provides more conservative results compared to the others. Complicated interactions occur in Boolean variable manipulation, approximation, and the quantification of a seismic PSA model. The insights presented herein can assist PSA analysts to better understand the important theoretical principles associated with the quantification of seismic PSA models.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4095-4101
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• 2022

Following the climate-related disasters considered by several efforts, the nuclear capacity needs to double by 2050 compared to 2015. So, it is reasonable to investigate global warming incorporated with the fuzzy set theory for nuclear energy consumption in the aspect of fuzziness and nonlinearity of temperature variations. The complex modeling is proposed for the enhanced assessment of climate change where simulations indicate the degree of influence with the Boolean values between 0.0 and 1.0 in the designed variables. In the case of OIL, there are many 1.0 values between 20^th and 60^th months in the simulations where there are 10 times more for a 1.0 value in influence. Hence, the temperature variable can give the effective time using this study for 100 months. In the analysis, the 1.0 value in NUCLEAR means the highest influence of the modeling as the temperature increases resulting in global warming. In detail, the first influence happens near the 8th month and then there are four times more influences than effects in the early part of the temperature mitigation. Eventually, in the GLOBAL WARMING, the highest peak is around the 20^th month, and then it is stabilized.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.421-431
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• 2023

Nuclear power plants (NPPs) have technical specifications (Tech Specs) to ensure that the equipment and key operating parameters necessary for the safe operation of the power plant are maintained within limiting conditions for operation (LCO) determined by a safety analysis. The LCO of Tech Specs that identify the lowest functional capability of equipment required for safe operation for a facility must be complied for the safe operation of NPP. There have been previous studies to aid in compliance with LCO relevant to rule-based expert systems; however, there is an obvious limit to expert systems for implementing the rules for many situations related to LCO. Therefore, in this study, we present a retrieval methodology for similar LCO cases in determining whether LCO is met or not met. To reflect the natural language processing of NPP features, a domain dictionary was built, and the optimal term frequency-inverse document frequency variant was selected. The retrieval performance was improved by adding a Boolean retrieval model based on terms related to the LCO in addition to the vector space model. The developed domain dictionary and retrieval methodology are expected to be exceedingly useful in determining whether LCO is met.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11A
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• pp.936-944
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• 2003

In this paper, we propose an AND/XOR-based technology mapping method for field programmable gate arrays (FPGAs). Due to the fixed size of the programmable blocks in an FPGA, decomposing a circuit into sub-circuits with appropriate number of inputs can achieve excellent implementation efficiency. Specifically, the proposed technology mapping method is based on Davio expansion theorem to decompose a given Boolean circuit. The AND/XOR nature of the proposed method allows it to operate on XOR intensive circuits, such as error detecting/correcting, data encryption/decryption, and arithmetic circuits, efficiently. We conduct experiments using MCNC benchmark circuits. When using the proposed approach, the number of CLBs (configurable logic blocks) is reduced by 67.6% (compared to speed-optimized results) and 57.7% (compared to area-optimized results), total equivalent gate counts are reduced by 65.5 %, maximum combinational path delay is reduced by 56.7 %, and maximum net delay is reduced by 80.5 % compared to conventional methods.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.1
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• pp.5-14
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• 2014

Searchable encryption systems provide search on encrypted data while preserving the privacy of the data and the search keywords used in queries. Recently, interest on data outsourcing has increased due to proliferation of cloud computing services. Many researches are on going to minimize the trust put on external servers and searchable encryption is one of them. However, most of previous searchable encryption schemes provide only a single keyword boolean search. Although, there have been proposals to provide conjunctive keyword search, most of these works use a fixed field which limit their application. In this paper, we propose a field-free conjunctive keyword searchable encryption that also provides rank information of search results. Our system uses prime tables and greatest common divisor operation, making our system very efficient. Moreover, our system is practical and can be implemented very easily since it does not require sophisticated cryptographic module.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1958-1967
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• 2004

This paper describes the method to rapidly fabricate the large-sized physical model with the envelope model size of more than 600 mm${\times}$ 600 mm${\times}$ 600 mm using two type semi-automatic VLM-ST processes in connection with the reverse engineering technology. The fabrication procedure of the large-sized solid shape is as follows: (1) Generation of STL data from 3D scan data using 3D scanner, (2) generation of shell-type STL data by Boolean operation, (3) division of shell-type STL data into several pieces by solid splitting, (4) generation of USL data for each piece with VLM-Slicer, (5) fabrication of each piece by cutting and stacking according to USL data using VLM-ST apparatus, (6) completion of a shell-type prototype by zigzag stacking and assembly for each piece, (7) completion of a 3D solid shape by foam backing, (8) surface finish of a completed 3D solid shape by coating and sanding. In order to examine the applicability of the proposed method, the miniature of the Mount Rushmore Memorial has been fabricated. The envelope model size of the miniature of the Mount Rushmore Memorial is 1,453 mm${\times}$ 760 mm${\times}$ 853 mm in size. From the result of the fabricated miniature of the Mount Rushmore Memorial, it has been shown that the method to fabricate the large object using two type semi-automatic VLM-ST processes in connection with the reverse engineering technology are very fast and efficient.

• Journal of Internet Computing and Services
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• v.16 no.3
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• pp.33-41
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• 2015

In this paper, the simplification procedure of Karnaugh Map, which is essential to design digital logic circuits, was implemented as web-based educational Java applets. The learners will be able to experience interesting learning process by executing the proposed Java applets. In addition, since the proposed Java applets were designed to contain educational technologies by step-by-step procedure, the maximization of learning efficiency can be obtained. The learners can make virtual experiments on the simplification of digital logic circuits by clicking on some buttons or filling out some text fields. Furthermore, the Boolean expression and its schematic diagram occurred in the simplification process will be displayed on the separate frame so that the learners can learn effectively. The schematic diagram enables them to check out if the logic circuit is correctly connected or not. Finally, since the simplification algorithm used in the proposed Java applet is based on the modified Quine-McCluskey minimization technique, the proposed Java applets will show more encouraging result in view of learning efficiency if it is used as assistants of the on-campus offline class.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.82-90
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• 2002

BDD have become widely used for various CAD applications because Boolean functions can be represented uniquely and compactly by using BDD. The size of the BDD representation for a function is very sensitive to the choice of orderings on the input variable. Therefore, it is very important to find a good variable ordering which minimize the size of the BDD. Since finding an optimal ordering is NP-complete, several heuristic algorithms have been proposed to find good variable orderings. In this paper, we propose a variable ordering algorithm, Faster-${\mu}$0, based on the ${\mu}$0(microcanonical optimization). In the Faster-${\mu}$0 algorithm, the initialization phase is replaced with a shifting phase to produce better solutions in a fast local search. We find values for algorithm parameters experimentally and the proposed algorithm has been experimented on well known benchmark circuits and shows superior performance compared to various existing algorithms.

• Journal of the Korean Society for Library and Information Science
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• v.42 no.2
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• pp.445-466
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• 2008

The purpose of this study is to raise the importance of information literacy programs for professional secretaries and to present guidelines for organizing them. While the level of projects in secretaries' information service is defined as an influencing factor to the necessity of information literacy programs, the level of scholarships or secretarial science as a major is not. An analysis on education needs of secretaries recommended that curriculum should be composed of 15 topics such as: meta search engines, special search engines, boolean operators, digital libraries, usenet, information centers, internet reference sources, SDI, topic search request, document delivery service, e-journals, commercial databases, fulltext service, search strategy and general search engines.

• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.187-194
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• 2016

A single fire event within a fire area can cause multiple initiating events considered in internal events probabilistic safety assessment (PSA). For an example, a fire event in turbine building fire area can cause a loss of the main feed-water and loss of off-site power initiating events. This fire initiating event could result in special plant responses beyond the scope of the internal events PSA model. One approach to address a fire initiating event is to develop a specific fire event tree. However, the development of a specific fire event tree is difficult since the number of fire event trees may be several hundreds or more. Thus, internal fire events PSA model has been generally constructed by modifications of the pre-developed internal events PSA model. New accident sequence logics not covered in the internal events PSA model are separately developed to incorporate them into the fire PSA model. Recently, many fire PSA models have fire induced initiating event fault trees not shown in an internal event PSA model. Up to now, there has been no analytical comparative study on the constructions of fire events PSA model using internal events PSA model with and without fault trees of initiating events. In this study, the changing process of internal events PSA model to fire events PSA model is analytically presented and discussed.