• Journal of the Korean Geosynthetics Society
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• v.15 no.4
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• pp.17-23
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• 2016

This study assessed the behavior of rock pillar in tunnel asymmetric diverging area by using a three dimensional numerical analysis. The stability of pillar is very important for the ensure the stability of the tunnel asymmetric diverging area. Based on parameters affecting the behavior of rock pillar, this study evaluated different safety factors according to pillar width, depth and rock conditions. It turned out that as the rock pillar width increases, the change curve of safety factors in accordance with depth and rock conditions shows more of the nonlinear behavior. By the assessment of the minimum safety factor, a safety factor chart on the behavior of rock pillar in tunnel asymmetric diverging area was suggested.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.475-480
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• 2014

In the fields of researches associated with plant layout optimization, the main goal is to minimize the costs of pipelines for connecting equipment. However, what is the lacking of considerations in previous researches is to handle the multi floor processes considering the safety distances for domino impacts on a complex plant. The mathematical programming formulation can be transformed into MILP (Mixed Integer Linear Programming) problems as considering safety distances, maintenance spaces, and economic benefits for solving the multi-floor plant layout problem. The objective function of this problem is to minimize piping costs connecting facilities in the process. However, it is really hard to solve this problem due to complex unequality or equality constraints such as sufficient spaces for the maintenance and passages, meaning that there are many conditional statements in the objective function. Thus, it is impossible to solve this problem with conventional optimization solvers using the derivatives of objective function. In this study, the PSO (Particle Swarm Optimization) technique, which is one of the representative sampling approaches, is employed to find the optimal solution considering various constraints. The EO (Ethylene Oxide) plant is illustrated to verify the efficacy of the proposed method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.2
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• pp.273-279
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• 2019

Development of mountain area is increasing due to the demand for improvement of traffic convenience and development of underdeveloped area. Therefore, there frequently are sections where tunnels and interchanges are located close to each other. These sections do not only affect tunnel planning, types and length of interchanges, but also affect more on route selection. In Korea, several design criteria present each reference value but these values are very similar. In the situation, the minimum value among them is usually applied when planning roads and it could cause traffic safety problems in different site conditions. In this study, the problems of design speed, illuminance adaptation distance, and lane change intervals are analyzed by simulating the cases that the problem could occur when calculating the separation distance between tunnel and interchange. The results obtained from this study can be summarized as following: the driving speed should be applied in case that the site has a big gap between design speed and driving speed because the uniform application of the design speed is not safe; the illuminance adaptation distance should include the influence distance in the section affected by the direct light; in addition, the lane change distance should include the time to perceive the situation of the next lane after the lane change in the section required for successive lane change.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.51-57
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• 2019

A plant layout problem has a large impact on the overall construction cost of a plant. When determining a plant layout, various constraints associating with safety, environment, sufficient maintenance area, passages for workers, etc have to be considered together. In general plant layout problems, the main goal is to minimize the length of piping connecting equipments as satisfying various constraints. Since the process may suffer from the heat and friction loss, the piping length between equipments should be shorter. This problem can be represented by the mathematical formulation and the optimal solutions can be investigated by an optimization solver. General researches have overlooked many constraints such as maintenance spaces and safety distances between equipments. And, previous researches have tested benchmark processes. What the lack of general researches is that there is no realistic comparison. In this study, the plant layout of a real industrial C3MR (Propane precooling Mixed Refrigerant) process is studied. A MILP (Mixed Integer Linear Programming) including various constraints is developed. To avoid the violation of constraints, penalty functions are introduced. However, conventional optimization solvers handling the derivatives of an objective functions can not solve this problem due to the complexities of equations. Therefore, the PSO (Particle Swarm Optimization), which investigate an optimal solutions without differential equations, is selected to solve this problem. The results show that a proposed method contributes to saving the capital expenditures.

• Journal of the Society of Disaster Information
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• v.11 no.4
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• pp.597-606
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• 2015

Until now, u-turn lane installation methods have been studied variously. But, There is no specific standard yet. This study ranges are commercial area in Incheon metropolitan city through field investigation and presents specific design standard for efficient operation of left turn using a field data through calculating relevant permitted u-turn lane length and minimum separation distance from the front intersection to starting point of permitted u-turn lane in urban signalized intersections in commercial area. Relevant permitted u-turn lane length is found to be 32m and minimum separation distances from the front intersection to starting point of permitted u-turn lanes are 72m, 40m, 24m in case of 1 left turn lane, 2 left turn lanes and 3 left turn lanes respectively. By comparing result values and field data, they had a large difference under the similar situations in their lengths. This result is caused of no specific standard about design of u-turn lanes. If results of this study applied to design of u-turn lanes, signalized intersections in urban commercial areas would be operated more safety and efficiently.

• Journal of Internet Computing and Services
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• v.24 no.6
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• pp.171-180
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• 2023

Hydrogen energy technology is gaining importance in the era of the Fourth Industrial Revolution, offering military advantages when applied to military vehicles due to its characteristics such as reduced greenhouse gas emissions, noise, and low vibration. Korea's military has initiated the Army Tiger 4.0 plan, focusing on hydrogen application, downsizing, and AI-based smart features. The Ministry of National Defense plans to collaborate with the Ministry of Environment to expand hydrogen charging stations nationwide, anticipating increased deployment of military hydrogen vehicles. However, considering the Jet Fire and VCE(Vapor Cloud Explosion) nature of hydrogen, ensuring safety during installation is crucial. Current military guidelines specify a minimum safety distance of 2m from adjacent buildings for charging stations. Scientific methods have been employed to quantitatively assess the accident damage range of hydrogen, proposing a minimum safety distance beyond the affected area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.703-712
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• 2021

In this study, a formula was derived to calculate the damage impact distance using the Chemical Accident Response Information System (CARIS) so that local governments can decide on the evacuation and notification of 13 types of substances. The National Institute of Chemical Safety selected 16 out of 97 types of accident preparedness substances in 2018 and called them residents' evacuation preparedness substances. In a chemical accident, local governments should prepare for resident notification, such as emergency disaster texts. Using the CARIS in Chungju, this study modeled the damage-affected distances of 13 types of substances for the evacuation of residents. Under all conditions, the coefficient of determination R2 was 0.99 or higher, representing a range of at least 0.9921 to a maximum 0.9999. The relative standard deviation between the damage impact distance obtained using the calculation formula, and the CARIS result was compared. The minimum separation distance was corrected considering the actual chemical accident response situation, and the range was found to be between 0.58 and 5.97%. The damage impact distance can be calculated at the site using the calculation formula derived from the research, and local governments can determine whether to evacuate or notify residents.

• Journal of the Korean Institute of Gas
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• v.16 no.1
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• pp.15-21
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• 2012

An analysis was completed of the hazards distance of hydrogen accidents such as jet release, jet fire, and vapor cloud explosion(VCE) of hydrogen gas, and simplified equations have been proposed to predict the hazard distances to set up safety distance by the gas dispersion, fire, and explosion following hydrogen gas release. For a small release rate of hydrogen gas, such as from a pine-hole, the hazard distance from jet dispersion is longer than that from jet fire. The hazard distance is directly proportional to the pressure raised to a half power and to the diameter of hole and up to several tens meters. For a large release rate, such as from full bore rupture of a pipeline or a large hole of storage vessel, the hazard distance from a large jet fire is longer than that from unconfined vapor cloud explosion. The hazard distance from the fire may be up to several hundred meters. Hydrogen filling station in urban area is difficult to compliance with the safety distance criterion, if the accident scenario of large hydrogen gas release is basis for setting up the safety distance, which is minimum separation distance between the station and building. Therefore, the accident of large hydrogen gas release must be prevented by using safety devices and the safety distance may be set based on the small release rate of hydrogen gas. But if there are any possibility of large release, populated building, such as school, hospital etc, should be separated several hundred meters.

• Journal of Korean Society of Disaster and Security
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• v.9 no.2
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• pp.23-32
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• 2016

Today the issue of deterioration of industrial complexes that are located close to life space of residents has been raised as a cause of threats to the safety of local communities. In this study, in order to improve the current risk analysis and scope of community notification, simulated threat zones were comparatively analyzed by utilizing the threat zones of alternative accident scenarios and modes of seasonal weather, and the area with a high probability of damage upon the leakage of toxic substances was predicted by examining wind directions observed at each time slot for each season. In addition, limit evacuation time and minimum separation distance to minimize casualties were suggested, and a proposal to enable more reasonable safety measures for on-site workers and nearby residents made by reviewing the risk management plan currently utilized for emergency response.

• Explosives and Blasting
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• v.28 no.1
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• pp.27-39
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• 2010

Blast design equations based on the concept of scaled distances can be obtained from the statistical analysis on measured peak particle velocity data of ground vibrations. These equations represents the minimum scale distance of various recommendations for safe blasting. Two types of scaled distance widely used in Korea are the square root scaled distance (SRSD) and cube root scaled distance (CRSD). Thus, the design equations have the forms of $D/\sqrt{W}{\geq}30m/kg^{1/2}$ and $D/\sqrt[3]{W}{\geq}60m/kg^{1/3}$ in the cases of SRSD and CRSD, respectively. With these equations and known distance, we can calculate the maximum charge weight per delay that can assure the safety of nearby structures against ground vibrations. The maximum charge weights per delay, however, are in the orders of $W=O(D^2)$ and $W=O(D^3)$ for SRSD and CRSD, respectively. So, compared with SRSD, the maximum charge for CRSD increases without bound especially after the intersection point of these two charge functions despite of the similar goodness of fits. To prevent structural damage that may be caused by the excessive charge in the case of CRSD, we suggest that CRSD be used within a specified distance slightly beyond the intersection point. The exact limit is up to the point, beyond which the charge difference of SRSD and CRSD begins to exceed the maximum difference between the two within the intersection point.