• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.213-218
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• 2003

Because of the development of digital technology, modern digital instrumentation & control systems are being innovativly developed in industrial plants. Whereas, many analog systems are still being used in nuclear plants, because of the demerits of digital equipment. As known, the demerits of digital equipment are the uncertainty and weaknesses in ambient environments such as smoke & electromagnetic interference In an Integral Reactor, a digital I&C system will be composed of microprocessor, memory and network card. Designers will apply new technique for digital equipment. Thus, it is important for digital I&C systems to operate according to designed functions & performance in the ambient environments during a life cycle. Digital I&C systems should have tolerance in such environments and environment qualification should be concluded To acquire electromagnetic interference qualification of digital equipment, this paper suggests an EMI test requirement. Designers should consider the electromagnetic compatibility and test digital equipment according to each test procedure. This paper involves an EMI test requirement and the results analysis of EUT(Equipment Under Test). Test result analysis will be used as electromagnetic compatibility design guides for Integral Reactor I&C systems.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4367-4381
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• 2023

Nuclear power plants are increasingly being equipped with digital I&C systems. Although some probabilistic safety assessment (PSA) models for the digital I&C of nuclear power plants have been constructed, there is currently no specific internationally agreed guidance for their modeling. This paper presents an initiative by the OECD Nuclear Energy Agency called "Digital I&C PSA - Comparative application of DIGital I&C Modelling Approaches for PSA (DIGMAP)", which aimed to advance the field towards practical and defendable modeling principles. The task, carried out in 2017-2021, used a simplified description of a plant focusing on the digital I&C systems important to safety, for which the participating organizations independently developed their own PSA models. Through comparison of the PSA models, sensitivity analyses as well as observations throughout the whole activity, both qualitative and quantitative lessons were learned. These include insights on failure behavior of digital I&C systems, experience from models with different levels of abstraction, benefits from benchmarking as well as major contributors to the core damage frequency and those with minor effect. The study also highlighted the challenges with modeling of large common cause component groups and the difficulties associated with estimation of key software and common cause failure parameters.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1852-1858
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• 2007

To Increase availability and to enhance the safety, the modernization of Instrumentation & Control (I&C) systems is considered. The extended use of the digital technology lets nuclear power plants(NPPs) to replace their old analog systems with some proven digital systems. To adapt digital equipment to plants effectively and systematically, however, there must be an essential prerequisite, which is to evaluate current I&C equipment. This paper shows a practical methodology to evaluate the current status and reliability of I&C systems of NPPs using Reliability Evaluation System(RES) before performing upgrades or replacements for systems. The proposed method was applied to KORI Unit 2. The proposed method shows the current status of operating I&C systems effectively for upgrading I&C systems.

• Nuclear Engineering and Technology
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• v.44 no.6
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• pp.697-708
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• 2012

The majority of instrumentation and control (I&C) systems in today's nuclear power plants (NPPs) are based on analog technology. Thus, most existing I&C systems now face obsolescence problems. Existing NPPs have difficulty in repairing and replacing devices and boards during maintenance because manufacturers no longer produce the analog devices and boards used in the implemented I&C systems. Therefore, existing NPPs are replacing the obsolete analog I&C systems with advanced digital systems. New NPPs are also adopting digital I&C systems because the economic efficiencies and usability of the systems are higher than the analog I&C systems. Digital I&C systems are based on two technologies: a microprocessor based system in which software programs manage the required functions and a programmable logic device (PLD) based system in which programmable logic devices, such as field programmable gate arrays, manage the required functions. PLD based systems provide higher levels of performance compared with microprocessor based systems because PLD systems can process the data in parallel while microprocessor based systems process the data sequentially. In this research, a bistable trip logic in a reactor protection system (RPS) was developed using very high speed integrated circuits hardware description language (VHDL), which is a hardware description language used in electronic design to describe the behavior of the digital system. Functional verifications were also performed in order to verify that the bistable trip logic was designed correctly and satisfied the required specifications. For the functional verification, a random testing technique was adopted to generate test inputs for the bistable trip logic.

• Nuclear Engineering and Technology
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• v.36 no.2
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• pp.184-195
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• 2004

The multi-tasking feature of digital I&C equipment could increase risk concentration because the I&C equipment affects the actuation of the safety functions in several ways. Anticipated Transient without Scram (ATWS) is a typical case of safety function failure in nuclear power plants. In a conventional analysis, mechanical failures are treated as the main contributors of the ATWS. This paper quantitatively presents the probability of the ATWS based on a fault tree analysis of a Korea Standard Nuclear Power Plant is also presented. An analysis of the digital equipment in the digital plant protection system. The results show that the digital system severely affects the ATWS frequency. We also present the results of a sensitivity study, which show the effects of the important factors, and discuss the dependency between human operator failure and digital equipment failure.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.6
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• pp.839-847
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• 2011

Instrumentation & Control(I&C) System in NPP(Nuclear Power Plant) plays a important role as the brain of human being, it performs protecting, controling and monitoring safety operation of NPP. Recently, the I&C system is digitalized as digital technology such as PLC, DSP, FPGA. The different aspect of digital system which use digital communication to analog system is that it has potential vulnerability to cyber threat in nature. Possibility that digital I&C system is defected by cyber attack is increasing day by day. The result of cyber attack can be adverse effect to safety function in NPP. Therefore, I&C system required cyber security counter-measures that protect themselves from cyber threat efficiently and also cyber security design should be taken into consideration at concept stage in I&C system development process. In this study, we proposed the digital asset analysis method for cyber security assessment of I&C system design in NPP and we performed digital asset analysis of I&C system by using the proposed method.

• Journal of IKEEE
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• v.7 no.2 s.13
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• pp.245-252
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• 2003

We designed a silicon pressure sensor interface circuit with digital calibration capability. The interface circuit is composed of an analog section and a digital section. The analog section amplifies the weak signal from the sensor and the digital section handles the calibration function and communication function between the chip and outside microcontroller that controls the calibration. The digital section is composed of I2C serial interface, memory, trimming register and controller. The I2C serial interface is optimized to suit the need of on-chip silicon microsensor in terms of number of IO pins and silicon area. The major part of the design is to build a controller circuit that implements the optimized I2C protocol. The designed chip was fabricated through IDEC's MPW. We also made a test board and the test result showed that the chip performs the digital calibration function very well as expected.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.7
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• pp.623-629
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• 2013

This paper presents the implementation result of the EEG(electroencephalogram) signal transmission protocol and its test platform. EEG measured by a dry-type electrode is directly converted into digital signal by ADC(analog-to-digital converter). Thereafter it is transferred DSP(digital signal processor) platform by $I^2C$(inter-integrated circuit) protocol. DSP conducts the pre-processing of EEG and extracts feature vectors of EEG. In this work, we implement the $I^2C$ protocol with 16 channels by using 10 or 12-bit ADC. In the implementation results, the overhead ratio for the 4 bytes data burst transmission measures 2.16 and the total data rates are 345.6 kbps and 414.72 kbps with 10-bit and 12-bit 1 ksps ADC, respectively. Therefore, in order to support a high speed mode of $I^2C$ for 400 kbps, it is required to use 16:1 and $(8:1){\times}2$ ratios for slave:master in 10-bit ADC and 12-bit ADC, respectively.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.6
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• pp.87-93
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• 2012

In this paper, we propose an analog-to-digital converter to set the address of a I2C slave chip. The proposed scheme converts a fixed voltage between 0 and VDD to the digital value which can be used as the address of the slave chip. The rising time and the falling time are measured with digital counter in a serially connected RC circuit, while the circuit is being charged and discharged with the voltage to be measured. The ratio of the two measured values is used to get the corresponding digital value. This scheme gives a strong point which is to be implementable all the parts except comparator using digital logic. Although the method utilizes RC circuit, it has no relation with the RC value if the quantization error is disregarded. Experimental result shows that the proposed scheme gives 32-level resolution thus it can be used to configure the address of the I2C slave chip.

• Honam Mathematical Journal
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• v.37 no.1
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• pp.135-147
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• 2015

Owing to the notion of a normal adjacency for a digital product in [8], the study of product properties of digital topological properties has been substantially done. To explain a normal adjacency of a digital product more efficiently, the recent paper [22] proposed an S-compatible adjacency of a digital product. Using an S-compatible adjacency of a digital product, we also study product properties of digital topological properties, which improves the presentations of a normal adjacency of a digital product in [8]. Besides, the paper [16] studied the product property of two digital covering maps in terms of the $L_S$- and the $L_C$-property of a digital product which plays an important role in studying digital covering and digital homotopy theory. Further, by using HS- and HC-properties of digital products, the paper [18] studied multiplicative properties of a digital fundamental group. The present paper compares among several kinds of adjacency relations for digital products and proposes their own merits and further, deals with the problem: consider a Cartesian product of two simple closed $k_i$-curves with $l_i$ elements in $Z^{n_i}$, $i{\in}\{1,2\}$ denoted by $SC^{n_1,l_1}_{k_1}{\times}SC^{n_2,l_2}_{k_2}$. Since a normal adjacency for this product and the $L_C$-property are different from each other, the present paper address the problem: for the digital product does it have both a normal k-adjacency of $Z^{n_1+n_2}$ and another adjacency satisfying the $L_C$-property? This research plays an important role in studying product properties of digital topological properties.