• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1999년도 추계학술발표회요약집
• /
• pp.222.2-222
• /
• 1999

• 전기학회논문지
• /
• 제56권10호
• /
• pp.1852-1858
• /
• 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
• /
• 제44권6호
• /
• pp.663-672
• /
• 2012

As software based digital I&C (Instrumentation and Control) systems are used more prevalently in nuclear plants, enhancement of software dependability has become an important issue in the area of nuclear I&C systems. Critical attributes of software dependability are safety and reliability. These attributes are tightly related to software failures caused by faults. Software testing and V&V (Verification and Validation) activities are hence important for enhancing software dependability. If the risky modules of safety-critical software can be predicted, it will be possible to focus on testing and V&V activities more efficiently and effectively. It should also make it possible to better allocate resources for regulation activities. We propose a prediction technique to estimate risky software modules by adopting machine learning models based on software complexity metrics. An empirical study with various machine learning algorithms was executed for comparing the prediction performance. Experimental results show SVMs (Support Vector Machines) perform as well or better than the other methods.

• Nuclear Engineering and Technology
• /
• 제44권6호
• /
• pp.697-708
• /
• 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.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 2004년도 추계학술발표회 발표논문집
• /
• pp.225-226
• /
• 2004

• 전기학회논문지P
• /
• 제63권4호
• /
• pp.290-294
• /
• 2014

PID(Proportional, Integral, Derivative) controller is the most popular process controllers in nuclear power plants. The optimized parameter setting of the process controller contributes to the stable operation and the efficiency of the operating nuclear power plants. PID parameter setting is tuned when new process control systems are installed or current process control systems are changed. When the nuclear plant is shut down, a lot of PID tuning methods such as the Trial and Error method, Ultimate Oscillation method operation, Ziegler-Nichols method, frequency method are used to tune the PID values. But inadequate PID parameter setting can be the cause of the unstable process of the operating nuclear power plant. Therefore the results of PID parameter setting should be simulated, optimized and finally verified. This paper introduces the simulation method of PID tuning to optimize the PID parameter setting and confirms them of the actual PID controller in the operating nuclear power plants. The simulation method provides the accurate process modeling and optimized PID parameter setting of the multi-loop control process in particular.

• 기술사
• /
• 제43권2호
• /
• pp.45-52
• /
• 2010

At the end of last year, Korean nuclear power plants, APR-1400 and a research reactor have been contracted to build plants at United Arab Emirates and Jordan. Since 1959, a historical background of nuclear technologies in Korea is summarized. The safety requirements for Instrumentation and Control (I&C) systems in Nuclear Power Plants (NPP) are discussed. Specific descriptions on the typical safety classification of I&C systems, the definitions of the electrical class 1E and the countermeasures against common caused failures are provided. And summaries of typical I&C systems such as the protection systems, the control systems, the instrumentations, the monitoring systems and a control room in NPP are introduced. Strict requirements on the development of the digital computer systems in nuclear applications are described.

• Nuclear Engineering and Technology
• /
• 제53권11호
• /
• pp.3694-3703
• /
• 2021

Instrumentation and Control systems (I&C) play a significant role in nuclear power plants (NPP) and other safety critical systems (SCS). We have conducted a rigorous study and discussions with experienced practitioners worldwide the strategy for the development of I&C systems to investigate the several aspects related to their dependability. We discussed with experienced practitioners that work on nuclear domain with the intention of knowing their approach, they use day-to-day for the development of such systems. The aim of this research is to obtain to provide guidance to those building I&C systems of NPP and have implications on state engineering licensure boards, in the determination of legal liability, and in risk assessment for policymakers, corporate governors, and insurance executives.

• 한국산학기술학회논문지
• /
• 제11권9호
• /
• pp.3451-3457
• /
• 2010

사이버보안성 평가는 대상이 되는 시스템이 사이버보안의 목적에 효과적으로 부합하는지 여부를 판단하는 방법이다. 사이버보안성 평가는 시스템의 사이버보안에 대한 신뢰 수준을 측정하고, 관리적 기술적 운영 측면에서의 사이버보안 척도가 요구된 바와 같이 이행되는지를 확인하는 데 필요하다. 최근 원전 계측제어시스템은 디지털 기술의 적용으로 인해 사이버보안에 관한 기술적 및 관리적 대책이 수립되도록 요구되고 있으나, 동 시스템의 사이버보안성 평가 방법론을 포함한 전반적인 사이버보안 프로그램이 마련되어 있지 않은 실정이다. 본 논문은 원전 계측제어 시스템에 적합한 정성적 사이버보안성 평가 방법론을 제시한다. 제안되는 방법론은 원전 계측제어 시스템의 사이버보안에 대한 강점과 취약점을 평가함으로써 원전 계측제어 시스템의 사용자에게 도움이 될 수 있다. 또한, 이 방법론은 원전 계측제어 시스템의 개발자, 감사자 및 규제자가 사이버보안의 관리적, 운영적 및 기술적 통제 항목을 검토하는 지표로 활용될 수 있을 것으로 판단된다.

• 한국가축번식학회지
• /
• 제19권2호
• /
• pp.95-104
• /
• 1995

Mouse mammary epithelial cells(NMuMG) were maintained onto 6-well plates (3$\times$105 cells/well) or chambered slide (1$\times$104 cells/well), in DMEM supplemented with 10% fetal calf serum. After serum starvation for 24 hours, DMNB (1$\mu$M) was added and exposed to UV light (300nm, 3 second pulse) after 2 hours from DMNB addition in order to activate DMNB which induces a rapid transient increase in intracellular cAMP upon UV irradiation. EGF (100ng/ml) and/or IGF-I (10ng/ml) were treated at the time of UV irradiation. Nuclear labeling index was estimated as percent of nuclear labeled cells(percent of S phase of cells) by incorporation of 3H-thymidine into DNA(1 hour pulse with 1$\mu$Ci/ml). DMNB(1$\mu$M), EGF (100ng/ml) and/or IGF-I (10ng/ml) signifciantly increased nuclear labeling index than those of control (P<0.05). Addition of DMNB＋EGF or DMNB＋EGF＋IGF-I showed the interaction effect in nuclear labeling index (P<0.05). Protein kinase A activities by addition of EGF, IGF-I or EGF＋IGF-I were 10.5, 9.8 or 9.4 unit/mg protein, respectively, and no statistical difference was found in comparison with control (P>0.05). Additon of DMNB＋EGF showed the moderate interaction effect on tyrosyl kinase activity (P<0.1). In the fluorography analysis, there were no specific protein phosphorylation patterns were found at 1 or 15 minute by addition of DMNB. EGF and/or IGF-I. These results suggest that the interaction effect in nuclear labeling index by addition DMNB and EGF could be mediated through the modulation of tyrosyl kinase activity by cAMP.