• Journal of Energy Engineering
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• v.27 no.4
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• pp.27-35
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• 2018

The passive containment cooling system (PCCS) has been designed to remove the released decay heat during the accident by means of the condensation heat transfer phenomenon to guarantee the safety of the nuclear power plant. The heat removal performance of the PCCS is mainly governed by the condensation heat transfer of the steam-air mixture. In this study, the heat removal performance of the PCCS was evaluated by using the MARS-KS code with a new empirical correlation for steam condensation in the presence of a noncondensable gas. A new empirical correlation implemented into the MARS-KS code was developed as a function of parameters that affect the condensation heat transfer coefficient, such as the pressure, the wall subcooling, the noncondensable gas mass fraction and the aspect ratio of the condenser tube. The empirical correlation was applied to the MARS-KS code to replace the default Colburn-Hougen model. The various thermal-hydraulic parameters during the operation of the PCCS follonwing a large-break loss-of-coolant-accident were analyzed. The transient pressure behavior inside the containment from the MARS-KS with the empirical correlation was compared with calculated with the Colburn-Hougen model.

• Smart Media Journal
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• v.11 no.9
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• pp.30-38
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• 2022

It is important to grasp biometric data in real time for prompt action in the event of a safety accident at a work site where the risk of safety accidents exists. Among them, blood oxygen saturation is the most important factor in maintaining human life, so real-time oxygen saturation measurement and monitoring is necessary according to the situation as a preemptive response for worker safety management. By receiving real-time bio-signals from workers wearing health and life-risk protective clothing, and sharing and analyzing the worker's risk status in an external system, it is possible to diagnose the worker's current condition and efficiently respond to emergencies that may occur to the worker. In this paper, we propose a wearable oxygen saturation measurement platform technology that can monitor the risk of harmful gases and oxygen saturation of the wearer in real time and ensure the wearer's activity and safety in order to cope with emergency situations at the scene of an accident. If we overcome the limitations identified through the results of the proposed system later and apply improved biodata such as motion correction to the platform, we expect that it will be usable not only in hazardous gas environments, but also in hospitals and homes for emergency patients.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.69-76
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• 2008

Three failure cases of CNG composite vessels were reported since after January 2005. The 1st and 2nd accidents were indebted to vessel defect and installation mistake. The 3rd was caused by gas leak at pipe connections. In this paper various aspects were studied based on information of the three failure analysis, which must be improved for better safety of the CNG bus system. Overpressure region caused by vessel explosion was theoretically predicted and also assessed by PHAST program. Explosion of 120 l vessel under 20 MPa is equivalent to 1.2 kg TNT explosion. The predicted value by PHAST was more serious than theoretical one. However, actual consequence of explosion was much less than both of the predicted consequences. Since the CNG vessel was designed by the performance based design methodology, it is difficult to verify whether the required process and tests were properly conducted or not after production. If material toughness is not enough, the vessel should be weak in brittle fracture at early in the morning of winter season since the metal temperature can be lower than the transition temperature. If autofrettage pressure is not correct, fatigue failure due to tensile stress during repeated charging is possible. One positive aspect is that fire did not ocurred after vessel failure. This may be indebted to fast diffusion of natural gas which hindered starting fire.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.73-84
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• 2024

In this study, a quantitative risk impact assessment is performed using an ALOHA program to identify the risks when applying ammonia as fuel for combined cycle power plants as one of the solutions of climate change. The worst and the alternative accident scenarios are established for the Sejong combined cycle power plant and the effective ranges are calculated in terms of flammability, thermal radiation, overpressure and toxicity. The analysis results show that the toxic risk is the most critical and the effective distance is highly proportional to the mixing ratio of natural gas and ammonia by showing the Pearson's correlation coefficient over 98% as 0.991, 0.987 and 0.989 for the Level Of Concern(LOC)-1, LOC-2 and LOC-3, respectively. In addition, the coefficients of linearity for LOC-1, LOC-2 and LOC-3 are calculated to 133, 70 and 29, respectively so it can be confirmed that the effective distance increases as the criterion decreases.

• Journal of the Korean Institute of Gas
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• v.20 no.3
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• pp.12-21
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• 2016

The demand for hydrogen is steadily increasing every year, and the facilities to produce and transfer hydrogen are being increased as well. Therefore, the possibility of a critical accident at hydrogen is expected to increase. Furthermore, the materials most likely to cause accidents at industrial sites are LPG 61%, hydrogen 12%, and LNG 10%, and the frequency of accidents due to these three combustible gases is relatively high. Thus, a CFD simulation was used to compute the explosion risk of danger-frequent combustible gases-hydrogen, LNG, and LPG-within a limited space, and the outcomes were compared and analyzed to review the risk of explosion of each gase within a limited space.

• Journal of the Korean Institute of Gas
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• v.22 no.5
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• pp.79-88
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• 2018

This study presents an evaluation method to estimate the damage scale of chemical storage tank of petrochemical plant due to the earthquake that is likely to occur among NaTech damage types. Based on this, the risk for damage reduction of chemical storage tanks was evaluated. As a result of the study, the risk of the storage tank increased greatly considering the earthquake, and the risk was greatly reduced as a result of evaluating the proposed measures to mitigate the damage impact on the earthquake. This study is expected to contribute to the research on the reduction of NaTech damages such as typhoons and thunderstorms as well as earthquakes, and to establish an emergency response plan. In the future, it is necessary to systematically study and institutionalize the risk reduction measures considering earthquakes.

• Journal of the Korea Convergence Society
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• v.6 no.3
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• pp.13-18
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• 2015

This paper is the study on the safe design of joint controling the pressure and temperature by connecting between pipes laying with the flexible joint. This study aims at decreasing the excessive pressure applied in the pipe and preventing the accident occurrence in order to solve the pipe damage by extraction and contraction due to the pressure of open air and transport gas. The flow properties of each model are investigated through the simulation analysis by applying three kinds of the flexible joints. When transport gas passes the flexible joint, the flow characteristics of heat, pressure and velocity at pipe laying are analyzed. It is thought to be contributed to the safe design due to the shape of the flexible joint by using the result of this study. And it is possible to be grafted onto the convergence technique at design and show the esthetic sense.

• Journal of Navigation and Port Research
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• v.30 no.1 s.107
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• pp.17-22
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• 2006

Recently, the demand for LNG(Liquefied Natural Gas) increases in our country and all over the world as well as building order for LNGC Because LNG is very dangerous cargo, the special know-how and attention for cargo handling to prevent an accident is required and big demand for deck officers in future is expected Thus, more specific and systematic education and training program by means of investigating the status of national LNGC officer's education and training. To accomplish this, IMO regulation and LNGC education program for Korea Institute of Maritime and Fisheries Technology, national shipping companies and Japanese T company were analyzed.

• Journal of the Korean Institute of Gas
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• v.18 no.3
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• pp.31-37
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• 2014

The aim of this work is to provide new experimental data on the pyrolysis characteristics and the minimum ignition energy (MIE) by using the same high-density polyethylene (HDPE) powder in domestic HDPE dust explosion accident. To evaluate the explosion sensitivity of HDPE, thermo-gravimetric analysis (TGA), differential scanning calorimeter (DSC) and MIE apparatus (MIKE-3, K$\ddot{u}$hner) was conducted. The measurements showed the volume median diameter of $61.6{\mu}m$ but the particle number density of 98 % in the range $0.4{\sim}4{\mu}m$. The ignition temperature from the results of TGA and DSC in HDPE dust layers was observed in the range of $380{\sim}490^{\circ}C$. MIE was measured under 1 mJ in the HDPE dust concentration of $1200{\sim}1800g/m^3$, it was found that the ratio of particle number density in the range $0.4{\sim}4{\mu}m$ was very high (98%).

• Journal of the Korean Institute of Gas
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• v.24 no.5
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• pp.20-28
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• 2020

In this study, the damage impact range in the case of a hydrofluoric acid leak accident was predicted using formula calculation, impact assessment simulations, and CFD simulations, and the results were compared and analyzed with the actual environmental impact report. Formula calculation was performed by using the leak source model and diffusion model. Impact assessment simulation was performed by KORA provided by the Korean Ministry of Environment, ALOHA by the United States Ministry of Environment, and PHAST, which is relatively widely used among commercialization programs, and the STAD-CMM+program for CFD simulation. Was utilized. Considering convenience, speed, acceptability, and economics from the user's perspective, ALOHA and KORA were the most appropriate methods for predicting the impact of hydrofluoric acid leakage. In addition, the results of this study will help to reduce unnecessary regulations in the process of government policy development and optimize the investment in the safety field of the company, effectively utilizing the limited resources of the government and the company.