• Journal of the Korean Society of Safety
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• v.37 no.5
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• pp.33-41
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• 2022

As the number of automobile registrations increases yearly, parking spaces that are located in downtown areas are increasing, and mechanical parking facilities are also increasing. Therefore, there is a high risk of accidents when installing and repairing a mechanical parking facility. In the preceding six years (from 2012 to 2018), the statistics that pertain to accidental disasters indicated that a total of 137 disaster victims were generated by the construction sector, 33 accidents occurred, and 10 people died. However, only the safety management items pertaining to accidents that occur during maintenance work and the use of the installed mechanical parking facilities are being studied; furthermore, there is no ongoing research with respect to the risk management that is conducted at the construction site. In 2017, the Korea Occupational Safety and Health Agency (KOSHA) announced the "Guidelines for Safe Installation and Maintenance of Mechanical Parking Equipment"; however, it is a safety guideline that is limited to the installation of basic protective equipment and to facility installation. There is no model for mechanical parking facilities that is indicated in the "Risk Assessment Model by Construction Industry Type", which is issued by the Safety and Health Corporation and is widely utilized for risk assessment in the construction industry; moreover, elevator installation work CODE N0: 22 is the only major example of a disaster. In this study, "risk assessment through a focus group interview" was performed, and data was derived from the "risk assessment of Article 41 (2) of the Industrial Safety and Health Act", which reflects the characteristics of the construction industry based on AHP analysis. The results of this study can be utilized for the risk assessment that is conducted during the construction stage of mechanical parking facilities.

• Geomechanics and Engineering
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• v.32 no.2
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• pp.233-244
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• 2023

With the increasing amount of resources required by the society development, mining operations go deeper, which raises the requirements of studying the effects of temperature on the physical and mechanical properties of coal and adjacent rock. For now, these effects are yet to be fully revealed. In this paper, a mechanical-electromagnetic radiation (EMR) test system was established to understand the mechanical deterioration characteristics of coal by the effect of thermal treatment and its deformation and fracture characteristics under thermo-mechanical coupling conditions. The mechanical properties of high-temperature-treated coal were analyzed and recorded, based on which, reasons of coal mechanical deterioration as well as the damage parameters were obtained. Changes of the EMR time series under unconstrained conditions were further analyzed before characteristics of EMR signals under different damage conditions were obtained. The evolution process of thermal damage and deformation of coal was then analyzed through the frequency spectrum of EMR. In the end, based on the time-frequency variation characteristics of EMR, a method of determining combustion zones within the underground gasification area and combustion zones' stability level was proposed.

• International Journal of Safety
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• v.7 no.1
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• pp.30-34
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• 2008

For the purpose of establishing basic design standards for the manufacture of wheelchairs, a dummy for an ISO-standard wheelchair was modeled for use with a manufactured wheelchair, and the safety and performance of the wheelchair were examined through numerical simulations.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.3
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• pp.256-263
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• 2009

After several PWSCCs were found in Bugey(France), Ringhals(Sweden), Tihange(Belgium), Oconee, Arkansas, Crystal Fever, Davis-Basse, VC Summer(U.S.A.), Thuruga(Japan), USNRC and PNNL started the research on PWSCC, that is, the PINC project. USNRC required KINS to participate in the PINC project in May 2005. KINS organized the Korean consortium at March 2006 and Pre-RRT for RVHP were performed for the preparation of PINC RRT. Through these preliminary RRT, Korea NDE teams can learn and develop the detection and sizing technique for RVHP dissimilar metal weld. These techniques are now being prepared in Korea and need to be utilized for the In-service inspection of the RVHP and BMI of Korea Nuclear Power Plants. PINC RRT mock-ups will be helpful to training.

• Journal of the Korean Institute of Gas
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• v.7 no.2 s.19
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• pp.42-47
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• 2003

To prevent major accident from toxic gas release, explosion, or fire in chemical processes, it needs dynamic control of human error with mechanical failure. Although most of major accidents occur with a coupling of human error and mechanical failure, numbers of researches have studied human error and mechanical reliability independently, but no where cross each other, to reduce the risk in the process. This work focuses on the coincidence of human error and mechanical failure for management of human error, and on some important performance shaping factors to propose a method for improving safety effectively of the process industries.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4181-4194
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• 2022

Main steam safety valves are commonly used in nuclear power plants to provide final protections from overpressure events. Blowdown and dynamic stability are two critical characteristics of safety valves. However, due to the parameter sensitivity and multi-parameter features of safety valves, using traditional method to design and/or optimize them is generally difficult and/or inefficient. To overcome these problems, a surrogate model-based valve design optimization is carried out in this study, of particular interest are methods of valve surrogate modeling, valve parameters global sensitivity analysis and valve performance optimization. To construct the surrogate model, Design of Experiments (DoE) and Computational Fluid Dynamics (CFD) simulations of the safety valve were performed successively, thereby an ensemble surrogate model (E-AHF) was built for valve blowdown and stability predictions. With the developed E-AHF model, global sensitivity analysis (GSA) on the valve parameters was performed, thereby five primary parameters that affect valve performance were identified. Finally, the k-sigma method is used to conduct the robust optimization on the valve. After optimization, the valve remains stable, the minimum blowdown of the safety valve is reduced greatly from 13.30% to 2.70%, and the corresponding variance is reduced from 1.04 to 0.65 as well, confirming the feasibility and effectiveness of the optimization method proposed in this paper.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.20-27
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• 2012

Mechanical seals are one of main components of high speed centrifugal pumps. So, it is very important to detect the faults (scratch, notch, indentation, wear) of mechanical seals since the damage of seal can cause a critical failures or accidents of machinery system. In the past, many researchers mainly performed to detect the seal fault using the time signals measured from sensors. Recently, studies are focused on the development of on-line real time monitoring system. But study on the feature parameters used for fault detection of mechanical seals has a little been performed. In this paper, we showed feature parameters extracted from accelerated and acoustic signals by using the discrete wavelet transform (DWT), alpha coefficient, statistical parameters. And also verified the possibility for fault detection of mechanical seal.

• Journal of the Korea Safety Management & Science
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• v.19 no.1
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• pp.63-71
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• 2017

As the demand for automation (or autonmation) or clean workplace has grown, the interest in the knowledge and skill regarding safety is rising in manager duty. Moreover, the importance of severity rate of injury has increased due to the enlargement of industry scale, even safety management area has developed. Thus, it is important that production managers, the core of the line process, realize the safety in their production line, even if a safety manager acts as a staff. However, in the duty oriented National Competency Standard (NCS), the education about the safety duty of production management part is insufficient. According to NCS, it is calculated production managers receive only 6.7% of whole safety education regarding the duty related the safety management for production manager in mechanical industry. However, the ability in safety is more demanded from production managers as the concept of "production and safety" turns into the concept of "production with safety". And then in this paper, we will compare and analyze the safety management duty in Korean NCS and the safety management duty in State Leaders Connecting Learning to Work in US manufacturing industry, in terms of the duty of the production manage in mechanical industry (05). And, we will develop the safety duty education system for production manager, by classifying the safety education in domestic mechanical industry into knowledge education, skill education, and attitude education with using AHP(Analytic Hierarchy Process).

• International Journal of Safety
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• v.4 no.2
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• pp.18-23
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• 2005

There are many electrical connections in the electric apparatus and most fires due to a fault contact result from a failure or misuse of electric apparatus and installation. The fault contact happens between electrical connections by the loose and the mechanical vibration. In this paper, we have investigated thermal and electrical properties of screwed electric contacts due to the mechanical vibration. The exciter was connected to a signal generator and power amplifier that provided the vibration frequency and amplitude. The vibration, temperature and voltage data were sent to a data acquisition system (DAQ). In the case that fault contact took place, the arc happened between the screwed electric contact and electric wire, heat due to the arc was transmitted to the adjacent insulators, for which the oxide could be generated more. In addition, a spark was generated and the insulator began to melt. Thus, the possibility of electrical fire became the highest in this case. Finally, when the fault contact takes place due to vibration, the hazard of an electric accident is very high.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.6
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• pp.957-962
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• 2013

This paper presents a performance testing device for safety fences of domestic professional baseball stadiums. Safety fences of professional stadiums have been fabricated and installed without adhering to any safety regulations, safety fences demonstrate critically low safety performances and many outfielders are severely injured every season. In this study, we designed and fabricated a performance testing device for safety fences and investigated its validity and reproducibility. A HIC (head injury criterion) was used for the statistical analysis of colliding data. We found that the optimal expulsion pressure and eliminated the accelerometer by replacing it with a velocity sensor using an estimation of the correlation between the momentum data obtained from velocity sensor and the impulse data from the accelerometer.