• Journal of the Korean Institute of Gas
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• v.22 no.1
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• pp.18-25
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• 2018

As the industries become more developed, the amounts of hazardous materials have been increased. Because of that, the possibility of accidents in plants is expected to increase. Especially, the dispersions of toxic materials cause serious effect to human life and environment, So it is very important to confirm safety distance of discharge accident. For this paper, we proposed new algorithms for toxic liquid, such as benzene and acrylonitrile. and using this argorithm, we are going to predict safety distance. The scenario of accidental release was assumed to be the release of entire quantity in 10 minutes is defined as worst-case scenario and Instantaneous release. Also the release from a partial rupture of line is used as an alternative case scenarios as NICS(National Institute of Chemical Safety) guidelines. Using ALOHA program and the algorithm for liquid toxic materials and suggested the graph, as well as correlated equations which can utilize emergency responders.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.10-20
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• 2022

About 21% of domestic chemical accidents are caused by transport vehicles for the past 10 years in Korea. Also, ammonia is a chemical substance with the largest number of accidents, 82 out of 672. In this study, supposed seasonal alternative scenario and worst scenario in case of releasing ammonia during bunkering it from tank lorry to fishing vessel and interpreted seasonal impact and range through Python, ALOHA, Probit analysis. Radiation impact range of possibility for 2nd burn and for maximum radiation in winter scenario, which is one of the alternative scenarios, was the highest(range: 41m, radiation: 5.01kW/m²) while overpressure impact was less than minimum standard of impact. And toxicity impact range(EPRG-2) of the summer scenario was the widest(5.0km) and took a very high death rate near accident area(port area, tourist area) according to Probit analysis. the wort scenario had a similar impact and range of summer scenario.

• Journal of the Korean Institute of Gas
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• v.26 no.4
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• pp.27-35
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• 2022

When LPG leaks from the storage tank, the gas try to sink to the ground because LPG is heavier than air. The gas easily creates vapor clouds causing aggressive accidents in no airflow. Therefore, It is important to prevent in advance by analyzing the damaged range caused from LPG leakage and vapor clouds. So, this study analyzed the range of damaged by LPG leakage and vapor clouds with consideration of the cold air flow which is generated by the topographical characteristics and the land use status at night time in the Jeju Hagari. As a result of the cold air flow using KLAM_21, about 2 m/s of cold air was introduced in from the southeast due to the influence of the terrain. The range of damaged by LPG leakage and vapor cloud was analyzed using ALOHA. When the leak hole size is 10 cm at the wind speed of 2 m/s, the range corresponding to LEL 60 % (12,600 ppm) was 61 m which range is expected to influence in nearby residential areas. These results of this study can be used as basic data to prepare preventive measures of accidents caused by vapor cloud. Forward, it is necessary to apply CFD modeling such as FLACS to check the vapor cloud formation due to LPG leakage in a relatively narrow area and to check the cause analysis.

• The Journal of the Convergence on Culture Technology
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• v.10 no.2
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• pp.407-417
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• 2024

The objective of this study is to predict and reduce potential damage caused by chlorine gas leaks, a hazardous material, when vehicles transporting it overturn due to accidents or other incidents. The goal is to forecast the anticipated damages caused by chlorine toxicity levels (ppm) and to design effective response strategies for mitigating them. To predict potential damages, we conducted quantitative assessments using the ALOHA program to calculate the toxic effects (ppm) and damage distances resulting from chlorine leaks, taking into account potential negligence of drivers during transportation. The extent of damage from toxic gas leaks is influenced by various factors, including the amount of the leaked hazardous material and the meteorological conditions at the time of the leak. Therefore, a comprehensive analysis of damage distances was conducted by examining various scenarios that involved variations in the amount of leakage and weather conditions. Under intermediate conditions (leakage quantity: 5 tons, wind speed: 3 m/s, atmospheric stability: D), the estimated distance for exceeding the AEGL-2 level of 2 ppm was calculated to be 9 km. This concentration poses a high risk of respiratory disturbance and potential human casualties, comparable to the toxicity of hydrogen chloride. In particular, leaks in urban areas can lead to significant loss of life. In the event of a leakage incident, we proposed a plan to minimize damage by implementing appropriate response strategies based on the location and amount of the leak when an accident occurs.

• The Journal of the Convergence on Culture Technology
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• v.10 no.2
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• pp.419-427
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• 2024

This study assessed the potential impact of gas leakage resulting from accidental damage to buried urban gas pipelines during perforating operation near subway construction sites. The risk of explosions due to ignition sources such as static electricity, arising from gas infiltrating the subway construction site through storm sewers and sewage pipes, was evaluated using the ALOHA program. The results of the threat zone calculation, which input various parameters of urban gas pipelines such as length, diameter, and pressure, indicated that the flammable area within the vapor cloud extended from 1.2 to 1.4 km (red zone), the blast area ranged from 0.8 to 1.0 km (yellow zone), and the jet fire extended from 45 to 61 m (red zone). This study demonstrates that within the flammable area of the vapor cloud, a specific combination of concentration and conditions can increase flammability. The blast area may experience explosions with a pressure of 1.0 psi, sufficient to break glass windows. In the event of a jet fire, high temperatures and intense radiant heat exposure lead to rapid fire propagation in densely populated areas, posing a high risk of casualties. The findings are presented in terms of the sphere of influence and threat zone ranges.

• Journal of information and communication convergence engineering
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• v.5 no.2
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• pp.88-92
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• 2007

In this paper, an SS-RRA protocol that is based on Code Division Multiple Access is proposed and analyzed under the integrated voice and data traffic load. The backward logical channels consist of slotted time division frames with multiple spreading codes per slot. The protocol uses a reservation mechanism for the voice traffic, and a random access scheme for the data traffic. A discrete-time, discrete-state Markov chain is used to evaluate the performance. The numerical results show that the performance can be significantly improved by a few distinct spreading codes.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.3
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• pp.1-7
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• 1999

일대다 형상을 갖는 통신시스템에서 많이 고려되는 예약 알로하 방식 매체접속제어 프로토콜의 성능은 예약 채널과 데이터 채널의 분배 양식에 의해 달라진다. 본 논문에서는 이 프로토콜을 직렬 2단 대기열 모델로 근사화하고, 데이터의 지연을 성능 척도로 하여 이를 줄이는 세가지 채널 할당 방식을 제시하였다. 그리고 이들에 대한 모의실험을 통해 그 동작 특성을 규명하고 성능을 평가하였다. 그 결과 이들의 성능은 트래픽의 특성, 특히 데이터 길이의 분산에 크게 의존하며, 일반적으로는 데이터에 우선권을 주는 방식이 우수하나, 데이터 길이의 분산이 큰 경우에는 비례배분 할당 방식이 우수한 것으로 평가되었다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.52-52
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• 2004

• Journal of Industrial Technology
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• v.12
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• pp.37-49
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• 1992

We proposed an integrated simulator scheme for communication networks. The network modeling and Analysis methologies are firstly discussed along the design procedure of a network simulator, and then, the structure, kernel, and user interfaces are defined for the simulator. Finally, for the verification of our approach, simulations are performed for a simple queueing network and a pure ALOHA system using Ptolemy, a multi-paradigm simulation enviroment.

• ETRI Journal
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• v.11 no.2
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• pp.137-149
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• 1989

패킷무선망의 성능분석을 위해 기제안된 경합형 프로토콜중 ISMA 방식을 선정하여 그에대한 throughput 및 delay 특성을 패킷발생률, SNR; 패킷 오율, 단말기의 이동속도, 변복조 방식 등 여러가지 시스팀 변수를 고려하여 모델링하고 평가하였으며, 특히 링크의 상태가 열악한 레일리 페이딩 환경에서의 해석을 행함으로서 이동 패킷 무선망에의 적용 가능성을 검토하였다. 또 해석결과를 바탕으로 컴퓨터 시뮬레이션에 의해 여타 방식과의 비교 평가를 행함으로서 ISMA 방식이 레일리 페이딩 환경에서 특히 우수함을 입증하고, 이동무선 환경에서 이용할 수 있음을 보였다. 시뮬레이션 결과에 의하면 ISMA 방식은 round trip delay가 비교적 길경우 CSMA나 slotted-ALOHA에 비교하여 매우 유효한 프로토콜이다.