• 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 the Korean Society of Safety
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• v.33 no.5
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• pp.51-59
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• 2018

It is difficult to determine the outdoor toxic level of hazardous chemicals that are leaked in the building, since there are no efficient ways to calculate how much percentage of the leaked chemicals is released into the outdoor atmosphere. In address to these problems, we propose a reasonable box model that can quantitatively evaluate the mass rate of the indoor chlorine leakage into the outside of the building. The proposed method assumes that the indoor chlorine leakage is fully mixed with the indoor air, and then the mixture of the chlorine and indoor air is exfiltrated into the outside of the building through effective leakage areas of the building. It is found that the exfiltration rate of the mixture of the chlorine and indoor air is strongly dependent on the temperature difference between inside and outside the building than the atmospheric wind speed. As compared with a conventional method that uses a vague mitigation factor, our method is more effective to evaluate the outdoor toxic threat zone of the chlorine that are leaked in the building, because it can consider the degree of airtight of the building in the evaluation of the threat zone.

• Journal of the Korean Society of Safety
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• v.32 no.2
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• pp.52-58
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• 2017

One of the most important elements of the management of chemical accident is threat zone estimation of fires, explosions and toxic gas dispersion based on chemical releases. The threat zone estimation is going to be standard of emergency response for the first defender and base line data of off-site risk assesment (hereinafter referred to as "ORA") and risk management plan (hereinafter referred to as "RMP"). Generally, ALOHA form EPA(U.S.) and Kora(from KOREA MINISTRY OF ENVIRONMENT) has been used for the off-site consequence analysis in Korea. However it is hard to predict accurate consequences rapidly in case of emergency. Hydrochloric acid is a multipurpose raw material used in many industrial applications such as chemical, metal and food industries. It is usually treated in concentrations from 10 ~ 35 %, and release accident have occurred frequently. In this study, we have developed a simplified estimating method and equation to calculate threat zone easily in case of emergency due to release accident of hydrochloric acid.

• Strategy21
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• s.40
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• pp.82-114
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• 2016

The purpose of this article is to analyze the progress of North Korea's SLBM threat, and to assess the technological capacity and threat level of its SLBMs. Currently, North Korea has approximately 1000 ballistic missiles, such as the SCUD, Musudan, and Nodong, in stock. This article pays close attention to the background and strategical implication behind North Korea's obsession with developing SLBMs despite possessing sufficient means to launch provocations with its current arsenal of ground based ballistic missiles and conventional weapons. Based on the abovementioned analysis, this article will recommend possible response directions for the ROK Armed Forces to North Korea's SLBM threat. It is highly difficult to detect SLBMs due to its stealthy nature, as it is launched underwater after covert infiltration. North Korea's SLBM is considered a game changer in that even one SLBM can significantly change the strategic balance of North East Asia. North Korea's SLBM test launch in August has made a 500km flight, landing 80km inside the JADIZ (Japan Air Defense Identification Zone), and as such, it is assessed that North Korea already possesses underwater ejection and cold launch capabilities. The most realistic response to North Korea's imminent SLBM threat is bolstering anti-submarine capabilities. ROK Armed Forces need to upgrade its underwater kill-chain by modernizing and introducing new airborne anti-submarine assets and nuclear-powered submarines, among many options. Moreover, we should integrate SM-3 missiles with the Aegis Combat system that possess strong detection capabilities and flexibility, thereby establishing a sea-based Ballistic Missle Defense (BMD) system centered around the Aegis Combat System, as sea-based ballistic missile threats are best countered out in the seas. Finally, the capabilities gap that could arise as a result of budgetary concerns and timing of fielding new assets should be filled by establishing firm ROK-US-Japan combined defense posture.

• Journal of Aerospace System Engineering
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• v.10 no.1
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• pp.118-126
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• 2016

North Korea has continued developing ballistic missiles with various ranges. Even through the recent launch long-range missiles, it can be inferred that North Korea's Missile technology has reached a level where it can even threaten the US. moreover, through the three times nuclear tests, North Korea is known to have succeeded at gaining 10~20KT of explosive power as well as the minimization and lightening of nuclear warhead. Considering the short length of war zone in Korean peninsula and the possibility of nuclear equipment, if be the most severe threat across the whole peninsula. Since the midcourse phase flight takes the longest time, ROK should establish the ability to intercept at this middle phase. From this perspective, this paper describes mission effect of a sea-based BMD system through empirical threat and flight characteristic analysis using MIT model that was not suggested in original research.

• Journal of the Korean Professional Engineers Association
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• v.41 no.2
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• pp.64-67
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• 2008

According to grow maritime activities in coastal zone, a threat increase to the marine environment from oil spill. The success or failure of initial effort depends on the adequacy of the plan and the ability of immediate execution. Successful response to oil spills requires critical information in real time topics, including spill data, environmental conditions, ecological factors. Diverse simulation provides tactical decision-makers with the information on the movement of pollutant.

• Journal of Forest and Environmental Science
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• v.34 no.1
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• pp.31-45
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• 2018

At present the biodiversity of the riparian forest is under threat due to various anthropogenic pressures. Hence study was conducted along the three unprotected zones of riparian forest in Dikhu river, Nagaland, north-east India in order to compared the diversity, distribution and population structure of riparian trees. In each zone $100{\times}100m^2$ plot were marked and subdivided into 20 plots of $10{\times}10m^2$. 10 plots on each side of the river were taken randomly covering 0.02 ha. Only tree with dbh ${\geq}10cm$ and dbh above 1.5 m above ground level were recorded as individual species. A total of 29 tree species belonging to 18 families were recorded from the three zones of the river. Tree species richness was highest at the middle zone (19) followed by upper (14) and lower zone (7). The most abundant species and family recorded at upper, middle and lower zones were Melia azaderach of Euphorbiaceae ($380\;stems\;ha^{-1}$), Terminalia chebula of Euphorbiaceae ($432.5\;stems\;ha^{-1}$) and Duabanga grandiflora of Lythraceae ($365\;stems\;ha^{-1}$) respectively. The ranges of diversity indices observed in the three zones were: Shannon-Wiener index (1.25-0.73), Simpson diversity index (0.42-0.93), Evenness index (0.47-0.37) and Index of co-dominance (0.75-0.94). Rest of other indices were also estimated and compared. Distribution of trees shows the contagious pattern common in the upper and middle zones and regular in the lower zone. The girth size class analysis demonstrated that the riparian forest is in less mature succession stage. This study emphasize the need for management and conservation of riparian forest by developing policy to declare the riparian zone as protected area to prevent further degradation and loss of biodiversity from these unregulated zones along the river.

• The Journal of the Korea Contents Association
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• v.21 no.5
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• pp.868-876
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• 2021

A school zone means a certain section designated among facilities, such as schools, childcare facilities, academies, etc., to protect children from the risk of traffic accidents. Since the school zone was established in September 1995, school zone accidents have not decreased even though it has been strengthened through a total of nine revisions until January 2021. This paper aims to present a standard model for child protection zones based on disaster prevention design. Methods of research included literature research, empirical research, and cognition research. Awareness survey was conducted on children, parents and drivers. Environmental surveys included crosswalks, motorways, pedestrian roads, and traffic lights. The investigation found that visual recognition of school zones by vehicle drivers was difficult, and found that motorcycles using pedestrian roads were a very threat to children. Accordingly, improved school zone standard model design centered on disaster prevention design was presented.

• Strategy21
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• s.33
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• pp.148-177
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• 2014

The regional security and stability in Northeast Asia has become more complicated because of a sudden establishment of China's Air Defense Identification Zone (ADIZ) on 23 November 2013. One dimensional conflicts on the territorial sovereignty over the islands between the regional States has developed into the two dimensional conflicts like maritime delimitations among the States concerned since they have all ratified the 1982 United Nations Convention on the Law of the Sea which adopts the 200 nautical mile Exclusive Economic Zone regime. Moreover, due to the notion of the outer limit of the continental shelf, the conflicts have developed into three dimensional ones in order to acquire more natural resources even in the seabed. To make matters worse, such three dimensional conflicts have expanded to the airspace as well. The paper will analyze what implications the sudden declaration of China's ADIZ have for the regional security in Northeast Asia from the perspectives of public international law. To this end, the paper 1) starts with the debates on the legal nature of the ADIZ, 2) identifies the Chinese government's political motives for the establishment of the ADIZ over the East China Sea, 3) assesses the responses of the regional States and the USA to the China's establishment of the ADIZ, and then 4) discuss what implications the overlapped ADIZ of the three key States in the region have for the regional security and stability.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.327-332
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• 2023

On December 26, 2022, North Korea's drone provocation resumed for the first time in eight years. The threat covered not only the Seoul metropolitan area but also the no-fly zone for the presidential office's security, and the South Korean military's response to it is not appropriate, which is a major controversy. In the midst of this, problems caused by the prohibition of small drones' flight and illegal intrusion into restricted areas are increasing in Korea, and the threat is becoming a reality, such as being used for terrorist attacks abroad. In this paper, the concept of "Counter-Drone" and related technologies were considered for these drone threats, and implications were derived through domestic and overseas small drone threats, and the direction of development of the Counter-Drone system was presented. North Korea's drone threat is expected to be more diversified, massified, and advanced, resulting in bolder attacks and provocations. Therefore, the South Korean military should push for early powering of the integrated control system and the conter drone system, joint and military cooperation in response to the threat of small drones, and the ability to carry out joint operations between South Korea and the U.S.