• Journal of the Korean Institute of Gas
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• v.16 no.4
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• pp.1-7
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• 2012

Systematic safety research by Korea Government has been made to enhance the safety of CNG (compressed natural gas) vehicles since the burst of compressed cylinder of an urban bus in August 9, 2010. This article summarizes some major activities to ensure the safety of CNG vehicles, which covers review of regulation, safety management system including standard of inspection and certification, and training program of inspectors and car mechanics. Specifically, the followings were reviewed; type of CNG cylinder, location of CNG cylinder, material and type of fuel line and vent line, modification of pipeline connection, installation of gas detector, installation of emergency shutdown valve, installation of protecting cover for cylinder, obligations for CNG vehicle filling station. improving periodical inspection, routine test on gas vehicles, training program for engaged in gas vehicles, and designation of safety manager for CNG bus company. This paper suggests how to improve safety of CNG vehicles as a result of review of above mentioned check items.

• Journal of the Korean Institute of Gas
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• v.19 no.1
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• pp.12-17
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• 2015

The core of the CNG fueling station is the compressor and most of CNG compressors in Korea require lubrication. Lubrication oil of CNG compressor that can be transferred into the pressure regulators and the engines of fueling system can cause a negative effect on NGV(Nature Gas Vehicle) performance during refueling due to oil Carry-over. In order to avoid the problem, it is necessary to enhance the quality of the compressed natural gas by measuring quantitatively the amount of the transferred oil. In this research, a sampling device and sampling tube were developed, which can be used with a gravimetric method of detection to measure CNG oil Carry-over. In addition, CNG samples were taken at 6 pre-selected CNG fueling stations and analysed for their trace oil Carry-over. The measured total oil Carry-over ranged from 2.569 to 6.509 ppm. This test measurements were compared with those of previous studies to verify the results.

• Journal of the Korean Institute of Gas
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• v.10 no.4 s.33
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• pp.63-69
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• 2006

With the increased interest in reducing air pollution, supply of natural gas for gas vehicles is increasing. Thus, the number of establishments of LNG and CNG stations is increasing as well. However, due to major gas accidents such as the fire and explosion accident of a Bucheon LPG station in 1998, it is difficult to establish a new station. In this research, we conducted qualitative hazard analysis fer LCNG/LNG multi-station by using the K-PSR method and proposed recommendations for hazard mitigation.

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.1-8
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• 2011

In this research, the safety trends and technologies of HCNG, a mixture of hydrogen and natural gas, are analyzed. This is an attracting alternative fuels to meet the strengthened automotive exhaust gas emission standards. HCNG is very important opportunities and challenges in that it is available the existing CNG infrastructures, meets the strengthened emission standards, and the technical, social bridge of the coming era of hydrogen. It is essential for the commercialization of HCNG that hydrogen - compressed natural gas blended fuel for use in preparation of various safety considerations included accidents scenario, safety distance, hydrogen attack, ignition sources and fire detectors are examined. Risk assessments also are suggested as one of permission procedure for HCNG filling station.

• Fire Science and Engineering
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• v.18 no.2
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• pp.57-67
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• 2004

The results of the risk assessing on general buses, consisting mainly of diesel-fueled buses, show that the frequency of the instantaneous release is 1.4${\times}$10$^{-3}$ /bus/year, from which the probability of the formation of fireball as a sub event becomes 1.7${\times}$104, and show that the leakage from the CNG-fueled buses is 0.002 event/year. Also, the frequency of gradual release due to a crack is estimated at 3.7${\times}$10$^{-3}$ /buses/year, and a subsequent probability at which this could lead to a jet flame as a sub event is 1.2${\times}$10$^{-3}$ This corresponds to 0.04event/year for the CNG-fueled buses. Dividing all the fired casualties by the running distance of diesel-fueled buses, the risk is 0.091 fire fatalities per 100-million miles. And the total fire risk fur CNG buses is approximately 0.17 per 100-million miles of travel. This means that CNG buses is twice or more dangerous than diesel buses. After all CNG buses are more susceptible to the major fires. In the aspect of the reliability of this study, generic models and the failure data used in assessing the risks of CNG buses are appropriate. However, more accurate physics-based models and databases should be supplemented with this study to provide the better results.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.773-779
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• 2021

CNG, which has recently been attracting attention as an alternative fuel in the transportation field to reduce emissions caused by global warming, is natural gas with abundant reserves and mainly composed of methane. Being in a gaseous state, natural gas requires the compression and liquefaction processes for transportation. Until now, general shut-off valves for liquid and gas piping have been developed in Korea, but there are few studies on shut-off valves for high pressures of about 200 bar. Currently, research on the flow analysis of valves is being actively conducted around the world. However, there are relatively many studies on large valves such as low-pressure valves or shipbuilding and marine, and the safety factor through structural analysis to check the structural integrity of the valve is checked at the design stage. Since it is necessary to have a fast response speed while minimizing pressure and speed loss due to flow change, basic research was conducted on the flow analysis of the valve to secure design data, and the numerical analysis was performed on high-pressure automatic shut-off valves applied to CNG refueling stations. After securing the basic valve shape through reverse engineering for advanced products, we compared the valve flow coefficient Cv coefficient with advanced products. As a result, it was found that the reverse engineering model was at the level of about 60%. However, we compared the Cv coefficient by modifying the reverse engineering model, and the result showed that it was improved to about 96%.

• The KIPS Transactions:PartC
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• v.16C no.5
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• pp.661-668
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• 2009

The Extended real-time Polling Service (ErtPS) is proposed tosupport QoS of VoIP service with silence suppression which generates variable size data packets in IEEE 802.16e systems. If the silence is suppressed, VoIP should support Comfort Noise Generation (CNG) which generates comfort noise for receiver's auditory sense to notify the status of connection to the user. CNG mode in silent-period generates a data with lower bit rate at long packet transmission intervals in comparison with talk-spurt. Therefore, if the ErtPS, which is designed to support service flows that generate data packets on a periodic basis, is applied to silent-period, resources of the uplink are used inefficiently. In this paper, we proposed the Improved ErtPS algorithm for efficient resource utilization of the silent-period in VoIP traffic supporting CNG. In the proposed algorithm, the base station allocates bandwidth depending on the status of voice at the appropriate interval by havingthe user inform the changes of voice status. The Improved ErtPS utilizes the Cannel Quality Information Channel (CQICH) which is an uplink subchannel for delivering quality information of channel to the base station on a periodic basis in 802.16e systems. We evaluated the performance of proposed algorithm using OPNET simulator. We validated that proposed algorithm improves the bandwidth utilization of the uplink and packet transmission latency

• Journal of the Korean Institute of Gas
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• v.18 no.3
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• pp.53-59
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• 2014

In this study, we suggest a system to build the monitoring model for compressed natural gas (CNG) stations, operated in only non-stationary modes, and perform the real-time monitoring and the abnormality diagnosis using principal component analysis (PCA) that is suitable for processing large amounts of multi-dimensional data among multivariate statistical analysis methods. We build the model by the calculation of the new characteristic variables, called as the major components, finding the factors representing the trend of process operation, or a combination of variables among 7 pressure sensor data and 5 temperature sensor data collected from a CNG station at every second. The real-time monitoring is performed reflecting the data of process operation measured in real-time against the built model. As a result of conducting the test of monitoring in order to improve the accuracy of the system and verification, all data in the normal operation were distinguished as normal. The cause of abnormality could be refined, when abnormality was detected successfully, by tracking the variables out of the score plot.

• Journal of the Korean Institute of Gas
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• v.13 no.1
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• pp.61-67
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• 2009

There are lots of energy facilities using gas(storage facility, compressed gas pipe, station, tank lorry) on the domestic. These major gas facilities cause major accidents associated with fire, explosion, toxic and etc. With the increased interest in reducing air pollution, supply of natural gas for gas vehicles is increasing. Thus, the number of establishments of LNG (Liquefied Natural Gas) and CNG(Compressed Natural Gas) stations is increasing as well. However, due to major gas accidents such as the fire and explosion accident of a Buchen LPG (Liquefied Petroleum Gas) station, it is difficult to establish a new station. In this research, we present quantitative risk assessment for LCNG;LNG multi-station and compare it result against individual risk criteria of HSE.

• Journal of Hydrogen and New Energy
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• v.28 no.6
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• pp.649-656
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• 2017

At present, hydrogen is emerging as a future energy source based on environment-friendly aspect, creation of new industry, and enhancement of domestic energy security. In accordance with it, the world's leading automobile companies are focusing on the development and commercialization of hydrogen electric vehicle technology, and each country is strengthening its hydrogen fueling station deployment strategy for its own country. Furthermore, the supply of hydrogen fueling stations is actively promoting under national support. More than 500 hydrogen fueling stations are being constructed, operated and planned around the world. The introduction of hydrogen energy is also progressing in Korea, by announcing road-map to supply hydrogen electric vehicles and hydrogen fueling stations by year. However, there is insufficient discussion on the capacity of hydrogen fueling station in Korea. Therefore, this study suggests the optimum capacity of hydrogen fuelling station for domestic hydrogen economy.