• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.24-32
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• 2021

Personal Air Vehicle (PAV), Cargo UAS (Cargo UAS), and existing manned and unmanned aircraft are key vehicles for urban air mobility (UAM), and should demonstrate compatibility for the design of aircraft systems. The safety assessment required by for certification to ensure safety and reliability should be systematically performed throughout the entire cycle from the beginning of the aircraft development process. However, with the increasing complexity of safety critical aviation systems and the application of state-of-the-art systems, conventional experience-based and procedural-based safety evaluation methods make ir difficult to objectively assess safety requirements and system safety. Therefore, Model-Based Safety Assessment (MBSA) using modeling and simulation techniques is actively being studied at domestic and foreign countries to address these problems. In this paper, we propose a Model-Based Safety Evaluation framework utilizing modeling and simulation-based integrated flight simulators. Our case studies on the Traffic Collision Availability System (TCAS) and Wheel Brake System (WBS) confirmed that they are practical for future safety assessments.

• Journal of Food Hygiene and Safety
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• v.16 no.2
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• pp.103-110
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• 2001

Predictive food microbiology(PFM) is an emerging area of food microbiology since the later 1980’s. It does apply mathematical models to predict the responses of microorganism to specified environmental variables. Although, at present, PFM models do not completely developed, models can provide very useful information for microbiological responses in HACCP(Hazard Analysis Critical Control Point) system and Risk Assessment. This study illustrates the possible use of PFM models(PMP: Pathogen Modeling Program win5.1) with milk in several elements in the HACCP system, such as conduction of hazard analysis and determination of CCP(Critical Control Points) and CL(Critical Limits). The factors likely to affect the growth of the pathogens in milk involved storage fixed factors were pH 6.7, Aw 0.993 and NaCl 1.3%. PMPwin5.1 calculated generation time, lag phase duration, time to level of infective dose for pathogens across a range of storage (Critical Control Points) and CL(Critical Limits). The factors likely to affect the growth of the pathogens in milk involved storage temperature, pH, Aw and NaCl content. The factors likely to affect the growth of the pathogens in milk involved storage temperature, pH, Aw and NaCl content. The variable factor was storage temperature at the range of 4~15$^{\circ}C$ and the fixed factors were pH 6.7, Aw 0.993 and NaC 1.3%. PMPwin5.1 calculated generation time, lag phase duration, time to level of infective dose for pathogens across a range of storage temperature.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.264-266
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• 2015

Currently as cyber threats grow up targeting nuclear power plants(NPP), licensees must guarantee that computer and information systems of nuclear facilities can be adequately protected against cyber attack. Especially critical system that cause illegal transfer of nuclear material and adverse impact to public safety need protecting. In this paper, we surveying the cyber threat examples targeted at NPP, and taxonomy the method of cyber security for NPPs in korea through analyzing the methodology to identify critical system and address cyber security controls for nuclear facilities.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.20-25
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• 2011

In this paper, we reviewed the spindle system's motor and bearing and its mode safety for optimal design of a high speed spindle system that exceeds DmN value of 1,500,000. We could verify that it has a separation margin during critical speed by performing critical speed analysis. Also, we have selected an optimal sensoring installation location and actually manufactured & installed the sensor by identifying the stress concentration position in the axial load through finite element analysis to install the built-in piezo electric type load sensor to the spindle housing that can measure and monitor the machining load during high speed rotation of the spindle. Reproducibility is also verified by calibrating the error through the sensor's sensitivity adjustment after comparing the output between the plate dynamoneters and the load sensor to confirm the reproducibility of the load sensor.

• Journal of Korean Clinical Nursing Research
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• v.21 no.3
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• pp.401-411
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• 2015

Purpose: This study was performed to develop a valid and reliable Korean Patient Classification System for Critical Care Nurses (KPCSC). Methods: Tertiary and general hospitals with various levels of ICU nurse staffing were included. To verify interrater reliability, data collectors and staff nurses of 15 ICUs in 11 hospitals classified 262 patients. To verify construct validity, the staff nurses classified 457 patients according to KPCSC comparing difference by medical department and type of stay in ICU. For conversion index, 195 patients from 10 ICUs in 7 hospitals were classified and nursing time was measured by 174 nurses, 7 head nurses, 18 charge nurses, 37 nurse aids and 1 secretary. Results: The developed KPCSC has 11 categories, 82 nursing activities and 115 criterias. Reliability was found to have high agreement (r=.96). Construct validity was verified by comparing differences in medical department and type of stay in ICU. According to scores, four groups in the KPCSC were identified. One score on the KPCSC indicates 6.12 minutes of nursing time. Conclusion: The findings show that the KPCSC can be used to measure new and complex nursing demands including rehabilitation and the safety of ICU patients.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.1-11
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• 1988

The flexible highway pavement is a layered structure. The safety of the pavement is a function of the load induced by traffic and the layer strength of asphaltic concrete mixture. Therefore, the probabilistic approach was applied to the pavement system to evaluate the reliability. Monte Carlo simulation technique was used for the reliability study. Data used were colleted from the field or literature. A critical tensile strength for each layer was estimated based on a target reliability from the simulation. The critical strength was evaluated by comparing the strengths with the actual surface distress. The result shows that the critical strength estimated in the probabilistic approach is valid for the current highway condition.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.2
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• pp.195-204
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• 2017

Predicting the failure life of automated manufacturing systems can reduce overall downtime, maintenance costs, and total plant operation costs. Therefore, there is a growing interest in fatigue failure mechanisms as the safety or service life assessment of manufacturing systems becomes an important issue. In particular, fretting fatigue is caused by repeated tangential stresses that are generated by friction during small amplitude oscillatory movements or sliding between two surfaces pressed together in intimate contact. Previous studies in fretting fatigue have observed size effects related to contact width such that a critical contact width exists where there is drastic change in the fretting fatigue life. However, most of them are the two-dimensional finite element analyses based on the plane strain assumption. The purpose of this study is to investigate the contact size effects on the three-dimensional finite element model of a finite width of a flat specimen and a cylindrical pad exposed to fretting fatigue. The contact size effects were analyzed by means of the stress and strain averages at the element integration points of three-dimensional finite element model. This study shows that the fretting fatigue life of manufacturing systems can be predicted by three-dimensional finite element analysis based on SWT critical plane model.

• KIISE Transactions on Computing Practices
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• v.23 no.6
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• pp.335-342
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• 2017

In the verification and validation procedures regarding the safety-critical software of nuclear power plants for the attainment of the requisite license from the regulatory body, it is difficult to judge the safety and dependability of the development, implementation, and validation activities through a simple reading and review of the documentation. Therefore, these activities, especially safety assurance activities, require systematic evaluation techniques to determine that software faults are acceptable level. In this study, a safety case methodology is applied in an assessment of the level and depth of the results of the development and validation of a manufacturer in its targeting of the bistable processor of a digital reactor protection system, and the evaluation results are analyzed. This study confirms the possibility of an effective supplementation of the existing safety demonstration method through the application of the employed safety case methodology.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.674-681
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• 2021

Cyber attacks targeting critical infrastructure are on the rise. Critical infrastructure is defined as core infrastructures within a country with a high degree of interdependence between the different structures; therefore, it is difficult to sufficiently protect it using outdated cybersecurity techniques. In particular, the distinction between the physical and logical risks of critical infrastructure is becoming ambiguous; therefore, risk management from a comprehensive perspective must be implemented. Accordingly, as a means of further actively protecting critical infrastructure, major countries have begun to apply their security and cybersecurity systems by design, as a more expanded concept is now being considered. This proactive security approach (CSbD, Cybersecurity by Design) includes not only securing the stability of software (SW) safety design and management, but also physical politics and device (HW) safety, precautionary and blocking measures, and overall resilience. It involves a comprehensive security system. Therefore, this study compares and analyzes security by design measures towards critical infrastructure that are leading the way in the US, Europe, and Singapore. It reflects the results of an analysis of optimal cybersecurity solutions for critical infrastructure. I would like to present a plan for applying by Design.

• Journal of the Korean Institute of Gas
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• v.8 no.1 s.22
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• pp.30-36
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• 2004

Although the usage of gas as one of the most economical energy source is ever expanding, numerous gas accidents occur as a result of negligence in safety management. The main reason behind such accident is that the current safety control system relies heavily on the manual control mechanism. This paper designed and developed a prototype of a computerized gas safety control system that automates such critical functions as the alarm sensing and the valve control. Since the system is connected through a digital network, the control can be performed remotely. Most importantly, the accidental risk or damage can be greatly reduced since the system monitors and reacts actively to gas leakage in real time.