• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.61-69
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• 2020

This study examined the braking characteristics of a heavy haul freight train with P4a distribution valves applied to domestic high-speed freight trains. A freight train was composed of 50 cars, which is twice the normal operation. A braking test was performed to confirm the characteristics of the braking of a heavy haul. The brake cylinder pressures were measured for emergency and service braking on the 1st, 10th, 20th, 30th, and 50th cars. Because the brake signal is transmitted to the pressure through the braking tube connected to the end of the train, the rear vehicle is braking later than the vehicle ahead. Therefore, it is necessary to predict the brake pressures in all cars in a train to supplement the results of the limited tests and calculate the braking distance. The pressure in each car was determined using empirical models of linear interpolation, stepwise, and exponential models, which provided reliable information. The predictive results of the empirical models were compared with the measured results, and the exponential model was predicted relatively accurately. These results are expected to contribute to the safe operation of heavy haul freight trains and can be used to predict the braking distance and calculate the level of impact between vehicles during braking.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.628-636
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• 2019

In various industrial processes, piping serves as a link between unit processes and is an essential installation for internal flow. Therefore, the optimum design of the piping system is very important in terms of safety and cost, which requires the estimation of the pressure drop, flow rate, pipe size, etc. in the piping system. In this study, we developed a software that determines pressure drop, flow rate, and pipe size when any two of these design variables are known. We categorized the flows into single phase, homogeneous two phase, and separated two phase flows, and applied suitable calculation models accordingly. We also constructed a system library for the calculation of the pipe material, relative roughness, fluid property, and friction coefficients to minimize user input. We further created a costing library according to the piping material for the calculation of the investment cost of the pipe per unit length. We implemented all these functions in an integrated environment using a graphical user interface for user convenience, and C # programming language. Finally, we verified the accuracy of the software using literature data and examples from an industrial process with obtained deviations of 1% and 8.8% for the single phase and two-phase models.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.599-606
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• 2019

Most facilities that manufacture products made from the hazardous materials operate at high temperatures and pressures. Therefore, there is a risk of fire explosion. In particular, an explosion accident is a major risk factor for facilities with hazardous materials, such as oil, chemical, and gas. Propylene is often used in sites producing basic raw materials and synthetic materials by addition polymerization at petrochemical plants. To prevent an explosion in the business using propylene, the explosion range with the oxygen concentration was calculated according to the changes in temperature and pressure using an inert gas, carbon dioxide. In these measurements, the temperature was $25^{\circ}C$, $100^{\circ}C$, and $200^{\circ}C$ and the amount of carbon dioxide in the container was $1.0kgf/cm^2.G$, $1.5kgf/cm^2.G$, $2.0kgf/cm^2.G$, and $2.5kgf/cm^2.G$. The explosion limit was related to temperature, pressure, and oxygen concentration. The minimum oxygen concentration for an explosion decreased with increasing temperature and pressure. The range of explosion narrowed with decreasing oxygen concentration. In addition, no explosion occurred at concentrations below the minimum oxygen concentration, even with steam and an ignition source of propylene.

• Tunnel and Underground Space
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• v.34 no.2
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• pp.89-103
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• 2024

In the disposal environment, gases can be generated at the interface between canister and buffer due to various factors such as anaerobic corrosion, radiolysis, and microbial degradation. If the gas generation rate exceeds the diffusion rate, the gas within the buffer may compress, resulting in physical damage to the buffer due to the increased pore pressure. In particular, the rapid movement of gases, known as gas breakthroughs, through the dilatancy pathway formed during this process may lead to releasing radionuclide. Therefore, understanding these gas generation and movement mechanism is essential for the safety assessment of the disposal systems. In this study, an experimental apparatus for investigating gas migration within buffer was constructed based on a literature review. Subsequently, a gas injection experiment was conducted on a compacted bentonite block made of Bentonile WRK (Clariant Ltd.) powder. The results clearly demonstrated a sharp increase in stress and pressure typically observed at the onset of gas breakthrough within the buffer. Additionally, the range of stresses induced by the swelling phenomenon of the buffer, was 4.7 to 9.1 MPa. The apparent gas entry pressure was determined to be approximately 7.8 MPa. The equipment established in this study is expected to be utilized for various experiments aimed at building a database on the initial properties of buffer and the conditions during gas injection, contributing to understanding the gas migration phenomena.

• The Journal of Engineering Geology
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• v.28 no.2
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• pp.217-246
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• 2018

During the selection and characterization of target formations in the Small-scale Offshore $CO_2$ Storage Demonstration Project in the Pohang Basin, we have carefully investigated the possibility of induced earthquakes and leakage of $CO_2$ during the injection, and have designed the storage processes to minimize these effects. However, people in Pohang city have a great concern on $CO_2$-injection-intrigued seismicity, since they have greatly suffered from the 5.4 magnitude earthquake on Nov. 15, 2017. The research team of the project performed an extensive self-investigation on the safety issues, especially on the possible $CO_2$ leakage from the target formation and induced earthquakes. The target formation is 10 km apart from the epicenter of the Pohang earthquake and the depth is also quite shallow, only 750 to 800 m from the sea bottom. The project performed a pilot injection in the target formation from Jan. 12 to Mar. 12, 2017, which implies that there are no direct correlation of the Pohang earthquake on Nov. 15, 2017. In addition, the $CO_2$ injection of the storage project does not fracture rock formations, instead, the supercritical $CO_2$ fluid replaces formation water in the pore space gradually. The self-investigation results show that there is almost no chance for the injection to induce significant earthquakes unless injection lasts for a very long time to build a very high pore pressure, which can be easily monitored. The amount of injected $CO_2$ in the project was around 100 metric-tonne that is irrelevant to the Pohang earthquake. The investigation result on long-term safety also shows that the induced earthquakes or the reactivation of existing faults can be prevented successfully when the injection pressure is controlled not to demage cap-rock formation nor exceed Coulomb stresses of existing faults. The project has been performing extensive studies on critical stress for fracturing neighboring formations, reactivation stress of existing faults, well-completion processes to minimize possible leakage, transport/leakage monitoring of injected $CO_2$, and operation procedures for ensuring the storage safety. These extensive studies showed that there will be little chance in $CO_2$ leakage that affects human life. In conclusion, the Small-scale Offshore $CO_2$ Storage Demonstration Project in the Pohang Basin would not cause any induced earthquakes nor signifiant $CO_2$ leakage that people can sense. The research team will give every effort to secure the safety of the storage site.

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.85-91
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• 2015

As the interest in hydrogen energy is being increased, it is a widely issue to develop a lot of hydrogen technologies in the field of production, storage, transportation, application and others. In the aftermath, there is a hydrogen town in Ul San, which is expected to expand application fields of hydrogen energy, as a demonstration project. The hydrogen town in Ul San can consist of high and low pressure part by the gas pressure. The high pressure part is managed by 'the high pressure gas safety control act'. And, low pressure part is managed by 'the guideline for the safety management of demonstration project of hydrogen town'. In this paper, to improve efficiency of safety management, the direction of safety management is reviewed by an analysis of low pressure hydrogen facility and safety management items. And then, some improvement directions are suggested. In the end, it is expected that the results of this study could help to activate construction of hydrogen town and improve efficiency of safety management as well.

• Food Science and Preservation
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• v.17 no.2
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• pp.190-195
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• 2010

Pressure, used as a minimal processing technology in the food industry, is a valuable tool ensuring microbiologically safe, shelf-stable fruit and vegetable production. Pressure could be used to deliver a greater variety of minimally processed products, as demanded by today's consumers. Weevaluated the effect of <400 MPa pressure, applied during chilling, on fresh fruit purees (strawberry, kiwi, aloe, and pomegranate) and vegetable extracts (from carrot and spinach) during cold storage (<$10^{\circ}C$) for 15-20 days. Samples were prepared in a processing facility in which total plate counts of falling and floating bacteria were controlled at $1{\times}100-10^1$ CFU/plate and $1{\times}10^2-10^3$ $CFU/m^3$ under conditions of $21-25^{\circ}C$ and 55-60% relative humidity. The aerobic plate counts of raw materials were less than $1{\times}10^3$ CFU/g. Evaluation parameters included microbiological safety, vitamin content, and sensory qualities. Although the overall quality of non-treated samples deteriorated with storage time at $10^{\circ}C$, samples pressurized at 250-350 MPa at $5-7^{\circ}C$ for 10 min showed less change, with no significant difference in microbiological safety, vitamin content, or sensory quality. The use of pressure extended the shelf-life during storage at $10^{\circ}C$.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.3
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• pp.13-20
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• 2011

In this paper, we proposed a system to raise gas safety management by using the wireless communication module and intelligent gas safety appliances. Our designed systems configure a micom-gas meter, an automatic extinguisher, sensors, and a wallpad. A micom-gas-meter monitors gas flow, gas pressure, and earthquake. An automatic fire extinguisher checks gas(combustible) leaks and temperature of $100^{\circ}C$ and $130^{\circ}C$. Sensors measure smoke and CO gas. In our novel system, a micom-gas meter cut off inner valve with warnings, an automatic fire extinguisher cut off middle valve and spray extinguishing materials, and sensors generate signals for smoke and CO when occurring gas risk. Gas safety appliances and sensors takes safety measures, and transmit those signal to a wallpad. The wallpad again transmit signal like events to a control server. Users can connect web pages for gas safety through B-ISDN and control and manage them. We hereby devised scenarios for gas safety and risk management, and demonstrated their effectiveness through experiments.

• Journal of the Korean Institute of Gas
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• v.15 no.6
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• pp.57-62
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• 2011

In this study, the optimized design for 130 liter storage fuel tank with 70MPa filling pressure has been investigated using a FEM technique and Taguchi design method. The strength safety of a composite fuel tank in which is fabricated by an aluminum liner of 6061-T6 material and carbon fiber wound composite layers of T800-24K has been analyzed based on the criterion of design safety of US DOT-CFFC and Korean Standard. The FEM computed results on the stress safety of 70MPa hydrogen gas tank were compared with a criterion of a stress ratio, 2.4 of US DOT-CFFC and Korean Standard, and indicated the safety. Thus, the optimized design elements based on the Taguchi's method were recommended as an aluminum liner thickness of 6.4mm, a carbon fiber laminate thickness in hoop direction of 31mm and a carbon fiber laminate thickness in helical direction of 10.2mm, which is represented by a design model of No. 5.

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.67-72
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• 2012

In this study, the leak-free performance and sealing endurance safety of CNG fueling nipple in which are related to the contact normal stress and equivalent true stress have been analyzed for CNG automobile using a finite element analysis. For the conventional circular o-rings and new double-lip o-rings with an initial compression rate of 15 percentages, the leak-free performance of double-lip o-rings with two contact sealing spots is 41% higher than that of the conventional circular o-rings with a contact sealing spot. The FEM computed results present that the leak-free endurance safety of double-lip o-rings with two contact sealing spots is 5% higher than that of the conventional circular o-rings for initial compression ratio of 15 percentages and a gas compression pressure of 8MPa. And, the maximum equivalent true stress of double-lip o-rings is 10.2% higher than that of the conventional circular o-rings for the leak-free endurance safety. This means that the double-lip o-ring may guarantee the extended sealing life compared to that of a conventional circular o-ring.