• Journal of the Society of Naval Architects of Korea
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• v.57 no.6
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• pp.322-330
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• 2020

This study deals with underwater explosion (UNDEX) characteristics of various non-explosive underwater shock sources for the development of non-explosive underwater shock testing devices. UNDEX can neutralize ships' structure and the equipment onboard causing serious damage to combat and survivability. The shock proof performance of naval ships has been for a long time studied through simulations, but full-scale Live Fire Test and Evaluation (LFT&E) using real explosives have been limited due to the high risk and cost. For this reason, many researches have been tried to develop full scale ship shock tests without using actual explosives. In this study, experiments were conducted to find the characteristics of the underwater shock waves from actual explosive and non-explosive shock sources such as the airbag inflators and Vaporizing Foil Actuator (VFA). In order to derive the empirical equation for the maximum pressure value of the underwater shock wave generated by the non-explosive impact source, repeated experiments were conducted according to the number and distance. In addition, a Shock Response Spectrum (SRS) technique, which is a frequency-based function, was used to compare the response of floating bodies generated by underwater shock waves from each explosion source. In order to compare the magnitude of the underwater shock waves generated by each explosion source, Keel Shock Factor (KSF), which is a measure for estimating the amount of shock experienced by a naval ship from an underwater explosionan, was used.

• Fire Science and Engineering
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• v.30 no.5
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• pp.1-8
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• 2016

Safety management in hazardous areas with potentially explosive gas atmospheres (here in after referred to as hazardous areas) in large scale facilities dealing with combustible or flammable materials at home and abroad is very important (significant) for the coexistence of the company and local society based on business continuity management (BCM) and reliance. For the safety management in hazardous areas, two systems are mainly used: (1) the control system for the prevention of combustible or flammable substances and (2) the explosion proof system for the elimination of ignition sources when flammable gases are leaked to inhibit the transition to fire or explosion accidents. While technology and regulations on explosion proof facilities or devices for electrical ignition sources are well developed and defined, those for thermal ignition sources need to be more developed and established. In this study, the internal combustion engine in hazardous areas was investigated to determine the risk of ignition. For this purpose, document searches were conducted on the relevant international standards and accidents cases and risk analysis reports. In addition, this study assessed the application cases of the diesel engine's safety equipment, such as spark arresters regarding the site of process safety management (PSM) system in central Korea. To practically apply these results to the hydrocarbon industry, the safety management method for explosion prevention in hazardous areas was provided by risk identification for ignition sources of internal combustion engines, such as diesel engines.

• Journal of the Korean Society of Safety
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• v.33 no.4
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• pp.21-29
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• 2018

In many companies handling flammable liquids, explosion-proof electrical equipment have been installed according to the Korean Industrial Standards (KS C IEC 60079-10-1). In these standards, hazardous area for explosive gas atmospheres has to be classified by the evaluation of the evaporation rate of flammable liquid leakage. The evaporation rate is an important factor to determine the zones classification and hazardous area distance. However, there is no systematic method or rule for the estimation of evaporation rate in these standards and the first principle equations of a evaporation rate are very difficult. Thus, it is really hard for industrial workplaces to employ these equations. Thus, this problem can trigger inaccurate results for evaluating evaporation range. In this study, empirical models for estimating an evaporation rate of flammable liquid have been developed to tackle this problem. Throughout the sensitivity analysis of the first principle equations, it can be found that main factors for the evaporation rate are wind speed and temperature and empirical models have to be nonlinear. Polynomial regression is employed to build empirical models. Methanol, benzene, para-xylene and toluene are selected as case studies to verify the accuracy of empirical models.

• Journal of the Korean Society of Safety
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• v.19 no.1
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• pp.66-71
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• 2004

This paper describes that the improved effects on the ignition limit are studied by parallel safety components for propane-air 5.25vol.% mixture gas in low voltage inductive circuits. The experimental devices are used in the IEC type spark ignition test apparatus. The improved effects on the ignition limit are respectively obtained as the maximum rising rate of 650%, 1,080% by composing parallel circuits between inductance and safety components (condenser and diode) as compared with disconnecting inductance with the safety components. The more values of inductance the higher improved effects of ignition limit rise. This improving method for the ignition limit is not concerned with the safety components. Diode appears to effect greatly better than condenser. It is considered that the result can be used for not only data for researches and development of intrinsically safe explosion-proof machines which are applied equipment and detectors used in hazardous areas but also for data for its equipment tests.

• Journal of the Korean Institute of Gas
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• v.22 no.4
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• pp.27-31
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• 2018

Classification of explosion hazard areas is very important in terms of cost and safety in the workplace handling flammable materials. This is because the radius of the hazardous area determines whether or not the explosion-proof equipment is installed in the electrical machinery and apparatus. From November 6, 2017, KS C IEC-60079-10-1: 2015 will be issued and applied as a new standard. It is important to understand and apply the difference between the existing standard and the new standard. Leakage coefficients and compression factors were added to the leakage calculation formula, and the formula of evaporation pool leakage, application of leakage ball size, and shape of explosion hazard area were applied. The range of the safety factor K has also been changed. Also, in the radius of the hazardous area, the existing standard applies the number of ventilation to the virtual volume, but the revised standard is calculated by using the leakage characteristic value. In this study, we investigated the differences from existing standards in terms of ventilation and dilution and examined the effect on the radius of the hazard area. Comparisons and analyzes were carried out by applying revised standards to workplaces where existing explosion hazard locations were selected. The results showed that even if the ventilation and dilution were successful, the risk radius was not substantially affected.

• Journal of the Korean Institute of Gas
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• v.23 no.4
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• pp.46-64
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• 2019

Technical practice code, KGS GC101 2018, for explosion hazard area selection and distance calculation of gas facility was enacted and implemented from July 12, 2018. This code includes whole contents of IEC60079-10-1 2015 (Explosive atmospheres Part 10-1: Classification of areas - Explosive gas atmospheres), and clarifies the interpretation of ambiguous standards or adds guidelines for standards. KGS GC101 is a method for classifying explosion hazard place types: (1) Determination of leak grade (2) Determination of leakage hole size (3) Determination of leakage flow (4) Determination of dilution class (5) Determination of ventilation effectiveness, finally (6) Determination of danger place (7) Explosion The range of dangerous places can be estimated. In order to easily calculate this process, the program (KGS-HAC v1.14, C-2018-020632) composed by Visual Basic for Application (Excel) language was produced by Korea Gas Safety Corporation. We will discuss how to use codes and programs to select and set up explosion hazard zones for field users.

• Fire Science and Engineering
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• v.18 no.1
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• pp.18-23
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• 2004

This paper describes the minimum ignition limits for propane-air 5.25 Vol.% mixture gases in low voltage inductive circiuts. The improved effects on the ignition limit are studied by parallel safety components(resistors) for propane-air 5.25 Vol.% mixture gas in low voltage inductive circuits. The experimental devices used in this test are the IEC type spark ignition test apparatus. The minimum ignition limits are controlled by the values of current in inductive circuit. Energy supplied from electric source is first accumulated at the inductance, it's extra energy is working as ignition source of the explosive gas. The improved effects on the ignition limit are respectively obtained as the maximum rising rate of 330% by composing parallel circuits between inductance and resistor as compared with disconnecting inductance with the safety components. The more values of inductance increase the higher improved effects of ignition limit rise. The less values of resistor the higher improved effects of ignition limit rise. It is considered that the result can be used for not only data for researches and development of intrinsically safe explosion-proof machines which are applied equipment and detectors used in dangerous areas but also for datum for its equipment tests.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.79-84
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• 1998

This paper describes the minimum ignition limit voltages for LPG-Air 5.25[Vol$\%$] mixture gas by discharge sparks in radio-frequency limits using RF power supply and IEC type ignition spark apparatus. As a result, the minimum ignition limit voltages is increased in proportional to the rate of increasing of frequency in LPG-Air mixture gas. Especially, the minimum ignition limit voltages increase remarkably between 3[KHz] and 10[KHz]. It is considered that ignition is caused by one discharge until 3[KHz] and, beyond 3[KHz] ignitiof is caused by more than two discharges. The reason is analyzed that energy loss is caused by existing pause interval between discharges. It is considered that the result can be used for not only data for researches and development of intrinsically safe explosion-proof RF machines which are applied tole-equipments and detectors used in dangerous areas but also for datum for its equipment tests.