• Journal of KIBIM
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• v.11 no.3
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• pp.34-44
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• 2021

This study quantitatively analyzes the work performance of the structural safety diagnosis team that diagnoses pipe racks. To this end, a method for evaluating the performance of the structural safety diagnosis team using the queuing model was proposed. For verification, the case of applying the existing method and the method of introducing a 3D laser scanner for one site was used. The period, number of people, and initial investment cost of each project were collected through interviews with case project experts. As a result of analyzing the performance of the structural safety diagnosis team using the queuing model, it was possible to confirm the probability of delay in the work of each project and the amount of delayed work. Through this, the cost (standby cost) when the project was delayed was analyzed. Finally, economic analysis was conducted in consideration of the waiting cost, labor cost, and initial investment cost. The results of this study can be used to decide whether to introduce 3D laser scanners.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.4
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• pp.329-334
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• 2021

Korean Air has set the goal of the first stage of the development of unmanned helicopters to perform in hovering flight by remote control. In order to achieve the development goal, Korean Air carried out system integration, ground test, and safety wire test in sequence after carrying out programmed depot maintenance and aircraft modification of manned aircraft, and verified the controllability and flight safety of the unmanned helicopter system step by step. In particular, it was confirmed that the safety wire test technique used in the final stage of verification was an effective method to verify flight safety and controllability for a fully unmanned helicopter system.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.506-519
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• 2024

To simulate the verification process using materials from a decommissioned reactor, a mock-up of the bottom-mounted instrument nozzle in the Kori 1 reactor, where the nozzle was attached to a plate by J-groove dissimilar metal welding, was fabricated. The mock-up distortion was quantified by measuring the plate surface displacement after welding. The residual stresses formed on the support plate surface and the inner surface of the nozzle were then analyzed using the hole-drilling method, contour method, and neutron diffraction. Welding simulations were performed using a 3D finite element method to validate the measured results. The measured and computed stress distributions on the support plate exhibited reasonable agreement. Conversely, the stresses on the inside of the nozzle were found to have an indisputable difference in the contour method and neutron diffraction measurements, which demonstrated strong tensile and compressive hoop stresses, respectively. The possible origins of such differences were investigated and we have provided some suggestions for a precise evaluation in the simulation. This study is expected to be useful in future research on decommissioned reactors.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.3
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• pp.211-215
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• 2009

As Programmable Logic Controllers (PLCs) are increasingly used to implement safety critical systems such as nuclear instrumentation & control system, formal verification for PLC based programs is becoming essential. This paper proposes a formal verification technique for PLC program implemented with function block diagram (FBD). In order to verify an FBD program, we translate an FBD program into a Verilog model and perform model checking using SMV model checker We developed a tool, FBD Verifier, which translates FBD programs into Verilog models automatically and supports efficient and intuitive visual analysis of a counterexample. With the proposed approach and the tool, we verified large FBD programs implementing reactor protection system of Korea Nuclear Instrumentation and Control System R&D Center (KNICS) successfully.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.9
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• pp.289-304
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• 2022

It is necessary to apply process algebra and logic in order to analyze and verify safety requirements for Smart IoT Systems due to distributivity and mobility of the systems over some predefined geo-temporal space. However the analysis and verification cannot be fully intuitive over the space due to the fact that the existing process algebra and logic are very limited to express the distributivity and the mobility. In order to overcome the limitations, the paper presents a new logic, namely for GTS-VL (Geo-Temporal Space-Visual Logic), visualization of the analysis and verification over the space. GTS-VL is the first order logic that deals with relations among the different types of blocks over the space, which is the graph that visualizes the system behaviors specified with the existing dTP-Calculus. A tool, called SAVE, was developed over the ADOxx Meta-Modeling Platform in order to demonstrate the feasibility of the approach, and the advantages and practicality of the approach was shown with the comparative analysis of PBC (Producer-Buffer-Consumer) example between the graphical analysis and verification method over the textual method with SAVE tool.

• Journal of the Korea Society of Computer and Information
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• v.27 no.12
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• pp.141-149
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• 2022

In this paper, we propose a design of CCTV enlcosure record management system based on blockchain. Since CCTV video records are transferred to the control center through enclosure, it is very important to manage the enclosure to prevent modulation and damage of the video records. Recently, a smart enclosure monitoring system with real-time remote monitoring and opening and closing state management functions is used to manage CCTV enclosures, but there is a limitation to securing the safety of CCTV video records. The proposed system detect modulated record and recover the record through hash value comparison by distributed stored record in the blockchain. In addition, the integrity verification API is provided to ensure the integrity of enclosure record received by the management server. In order to verify the effectiveness of the system, the integrity verification accuracy and elapsed time were measured through experiments. As a result, the integrity of enclosure record (accuracy: 100%) was confirmed, and it was confirmed that the elapsed time for verification (average: 73 ms) did not affect monitoring.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.16-23
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• 2023

The aircraft fuel system performs a number of functions such as supplying fuel, transferring fuel between fuel tanks, and measuring the amount of residual fuel in each fuel tank. Since it is a direct cause of fire hazard in crash incident, it is a must to improve survivability of crew members by designing the airframe to tolerate expected crash impact. The civil aviation authority requires intensive verification of the fuel system design to determine precise application of the airworthiness requirement. Research activity on airworthiness certification criteria and verification scheme is still insufficient, although it has a significant importance. In this paper, as part of a study to improve flight safety by developing guidelines for demonstrating fuel system crash resistance, analysis results of fuel system crash-related airworthiness certification standards, verification scheme, and cases study applicable to military rotorcraft have been reviewed.

• Journal of the Korea Safety Management & Science
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• v.15 no.3
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• pp.61-69
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• 2013

According to ISO 26262 (the international standard on functional safety for automotive industry), the functional safety should be considered during the whole automotive systems life cycle from the design phase throughout the production phase. In order to satisfy the standard, the automotive and related industry needs to take appropriate actions while carrying out a variety of development activities. This paper presents an approach to coping with the standard. Analyzing the standard indicates that the safety issues of the automotive systems should be handled with a system's view whereas the conventional approach to solving the issues has been practiced with focus on the component's level. The aforementioned system's view implies that the functional safety shall be incorporated in the system design from both the system's life-cycle view and the hierarchical view for the structure. In light of this, the systems engineering framework can be quite appropriate in the functional safety development and thus has been taken in this paper as a problem solving approach. Of various design issues, the analysis and verification of the safety requirements for functional safety is a key study subject of the paper. Note, in particular, that the conventional FMEA (failure mode effects analysis) and FTA (fault tree analysis) methods seem to be partly relying on the insufficient experience and knowledge of the engineers. To improve this, a systematic method is studied here and the result is applied in the design of an ABS braking system as a case study.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1871-1880
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• 2020

Round robin analyses for vessel failure probabilities due to PTS events are proposed for plant-specific analyses of all types of reactors developed in Korea. Four organizations, that are responsible for regulation, operation, research and design of the nuclear power plant in Korea, participated in the round robin analysis. The vessel failure probabilities from the probabilistic fracture mechanics analyses are calculated to assure the structural integrity of the reactor pressure vessel during transients that are expected to initiate PTS events. The failure probabilities due to various parameters are compared with each other. All results are obtained based on several assumptions about material properties, flaw distribution data, and transient data such as pressure, temperature, and heat transfer coefficient. The realistic input data can be used to obtain more realistic failure probabilities. The various results presented in this study will be helpful not only for benchmark calculations, result comparisons, and verification of PFM codes developed but also as a contribution to knowledge management for the future generation.

• Journal of Environmental Health Sciences
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• v.43 no.5
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• pp.360-369
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• 2017

Objectives: The organizational culture of small-scale enterprises is influenced by a lack of awareness of industrial accidents and a business-oriented culture. Therefore, the purpose of this study is to establish a correlation between chemical awareness and worker safety, which is the reason why a company's safety environment is responsible for human factor accidents. Methods: The research model established the organizational culture, human relationships, organizational relationships, workplace culture, safety climate, and safety parameters, all of which affect the perception of chemical substances, then established safety rankings, communication, safety regulations, and safety support. Results: In order to derive the results of this study, the satisfaction level was mostly derived from the degree of engagement (+) depending on the number of years worked, in the hierarchical regression analysis. During work with chemicals, the number of years spent on the level of the service was determined by the influence of the chemical (-). Based on this company, the occurrence of chemical accidents caused by chemical materials was felt to be felt at the risk of causing the hazard to be felt, the absence of physical damage was excluded from the variables. The other variables detected in the variables were $62.8{\pm}24.4$. Conclusion: As a result, it is necessary to develop a statistical model for the verification of the hierarchical regression analysis, and the relationship between safety and awareness of the dangers of chemicals and biological agents requires periodic safety training. Job satisfaction was found to be higher if the level of awareness was sufficient.