• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.134-140
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• 2023

Activated carbon is a carbonaceous material mainly used as a gaseous or liquid adsorbent. As fire-related accidents occur consistently due to the accumulation of heat of adsorption and oxidation of volatile organic compounds, the explosive characteristics and thermal stability of powdered and granular activated carbon made from coal and coconut shells were evaluated. As a result of the particle size analysis, the powdered activated carbon was in the particle size range (0.4~3) ㎛, and thermal properties such as exothermic onset temperature and decomposition behavior were analyzed using a differential scanning calorimetry and a thermogravimetric analysis. As a result of the evaluation of the explosion hazards for dust, both coal-based and coconut-based powdered activated carbon are classified as St1 class with weak explosion, but this is a relative and does not mean that the explosion hazards is absolutely low. Therefore, it is necessary to establish countermeasures for reducing the damage.

• Journal of the Korea Institute of Building Construction
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• v.21 no.5
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• pp.483-493
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• 2021

Urban overcrowding has created an explosive supply and demand for high-rise buildings. High-rise buildings are contributing to enhancing the image of the city by serving as focal points, but due to the stack effect, malfunction of elevator doors, difficulties in opening and closing the doors and windows of the outer wall, smoke and odors spreading to the upper floors, noise, energy loss, fire and pollutants have been causing various unexpected problems such as rapid spread of fire. This study classified high-rise buildings according to their vertical zoning, analyzed the causes of and solutions to the stack effect, and derived design and construction methods. Through the initial plan to block the outside air and securing airtightness through precise construction, we sought ways to secure the airtightness inside and outside the building by actively blocking the airflow from the lower floors. In addition, the facility solution can be a measure to reduce the specific phenomena caused by the stack effect, but it should only be applied to the minimum extent because the potential for secondary damage is high. This study emphasized the need for systematic stack effect management by suggesting design and construction measures for each vertical zoning of the causes and countermeasures of the stack effect. It is expected that this study will be helpful not only for design and construction, but also for building maintenance.

• Korean Security Journal
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• no.9
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• pp.201-235
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• 2005

This study is designed to contribute for development of Private Security Business by fact-finding in instruction and training of private security guard serviced in this realm and domestic and foreign guard service and modeling effective and rational instruction and training program based on drawn problem. For this study, basically I collected and analyzed documents, theses, and papers of the inside and outside of the country. For practical use of data, I used materials of private security related institutes and police agency. And for private security educating training programs of the inside and outside of the country, I collected materials on internet, and with the help of police agency and interpol. For korean private security company's educating training programs, I made a study with the interview of private security company's businessmen. This study's conclusion is as follows. In a domestic private security enterprise, when set theory instruction minimize instruction and training program and must set up instruction and training program as practical affairs center enemy instruction, and theory instruction must be composed for instruction me that it is connected to practical affairs instruction too. The instruction course of private security guard instruction and training program composed with a security outline, a security plan, an information-gathering, civilian expenses, a security way, terror and terrorism, a related law, security trial, electronic security, a security analysis technique, company introduction, instruction and training program about a professional tube with theory instruction. Practical affairs instruction composed with the selection and a preventive security, close contact attendance security, vehicle security, security driving the security martial arts and self-protection liquor, first aid, security equipment, a gun and shooting, a security protocol, customer satisfaction, facilities security and expenses, a fire fighting instruction, teamwork training, explosive and a dangerous substance, physical strength, a documentation practical affairs, service, instruction and training program about foreigh language instruction.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.321-330
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• 2011

Recently, the effects of high temperature and fiber content on the residual mechnical properties of high-strength concrete were experimentally investigated. In this paper, residual mechanical properties of concrete with water to cement (w/c) ratios of 0.55, 0.42 and 0.35 exposed to high temperature are compared with those obtained in fiber reinforced concrete with similar characteristics ranging from 0.05% to 0.20% polypropylene (PP) fiber volume percentage. Also, factors including pre-load levels of 20% and 40% of the maximum load at room temperature are considered. Outbreak time, thermal strain, length change, and mass loss were tested to determine compressive strength, modulus of elasticity, and energy absorption capacity. From the results, in order to prevent the explosive spalling of 50 MPa grade concretes exposed to high temperature, more than 0.05 vol. % of PP fibers is needed. Also, the cross-sectional area of PP fiber can influence the residual mechanical properties and spalling tendency of fiber reinforced concrete exposed to high temperature. Especially, the external loading increases not only the residual mechanical properties of concrete but also the risk of spalling and brittle failure tendency.

• Journal of the Korea Concrete Institute
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• v.28 no.6
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• pp.673-683
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• 2016

In recent years, frequent terror or military attack by explosion, impact, fire accidents have occurred. Particularly, World Trade Center collapse and US Department of Defense Pentagon attack on Sept. 11 of 2001. Also, nuclear power plant incident on Mar. 11 of 2011. These attacks and incidents were raised public concerns and anxiety of potential terrorist attacks on major infrastructures and structures. Therefore, the extreme loading researches were performed of prestressed concrete (PSC) member, which widely used for nuclear containment vessel and gas tank. In this paper, to evaluate the blast resistance capacity and its protective performance of bi-directional unbonded prestressed concrete member, blast tests were carried out on $1,400{\times}1,000{\times}300mm$ for reinforced concrete (RC), prestressed concrete without rebar (PSC), prestressed concrete with rebar (PSRC) specimens. The applied blast load was generated by the detonation of 55 lbs ANFO explosive charge at 1.0 m standoff distance. The data acquisitions not only included blast waves of incident pressure, reflected pressure, and impulse, but also included displacement, acceleration, and strains at steel, concrete, PS tendon. The results can be used as basic research references for related research areas, which include protective design and blast simulation under blast loading.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.790-803
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• 2019

The dioctyl terephthalic acid (DOTP) process produces plastic plasticizers by esterification of terephthalic acid with powder in the form of octanol. In this study, the dust explosion characteristics of terephthalic acid directly injected into the manhole in the form of powder in the presence of flammable solvent or vapor in the reactor of this process were investigated. Dust particle size and particle size distribution dust characteristics were investigated, and pyrolysis characteristics of dust were investigated to estimate fire and explosion characteristics and ignition temperature. Also, the minimum ignition energy experiment was performed to evaluate the explosion sensitivity. As a result, the average particle size of terephthalic acid powder was $143.433{\mu}m$. From the thermal analysis carried out under these particle size and particle size distribution conditions, the ignition temperature of the dust was about $253^{\circ}C$. The lower explosive limit (LEL) of the terephthalic acid was determined to be $50g/m^3$. The minimum ignition energy (MIE) for explosion sensitivity is (10 < MIE < 300) mJ, and the estimated minimum ignition energy (Es) based on the ignition probability is 210 mJ. The maximum explosion pressure ($P_{max}$) and the maximum explosion pressure rise rate $({\frac{dP}{dt}})_{max}$ of terephthalic acid dust were 7.1 bar and 511 bar/s, respectively. The dust explosion index (Kst) was 139 mbar/s, corresponding to the dust explosion grade St 1.

• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.47-59
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• 2024

Purpose: This study aims to propose measures for the prevention of fire and explosion accidents within manufacturing facilities by improving the existing classification criteria for hazardous locations based on the leakage patterns of flammable liquids. The objective is to suggest ways to safely manage ignition sources and combustible materials. Method: The hazardous locations were calculated using "KS C IEC 60079-10-1," and the calculated explosion hazard distances were visualized in 3D. Additionally, the formula for the atmospheric dispersion of flammable vapors, as outlined in "P-91-2023," was utilized to calculate the dispersion rates within the hazardous locations represented in 3D. Result: Visualization of hazardous locations in 3D enabled the identification of blind spots in the floor plan, facilitating immediate recognition of ignition sources within these areas. Furthermore, when calculating the time taken for the Lower Explosive Limit (LEL) to reach within the volumetric space of the hazardous locations represented in 3D, it was found that the risk level did not correspond identically with the explosion hazard distances. Conclusion: Considering the atmospheric dispersion of flammable liquids, it was concluded that safety management should be conducted. Therefore, a method for calculating the concentration values requiring detection and alert based on realistically achievable ventilation rates within the facility is proposed.

• Korean Security Journal
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• no.19
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• pp.105-138
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• 2009

This study's purpose is to present the improvement of effectiveness of security activity for international conference among Several Countries which can be held hereafter. On the basis of security activity problems originating in APEC that had been held in Busan in 2005. I made up questions three times to on the members of the police, military, fire figher and national intelligence service who had experienced in Busan APEC and recognition of possible problem and possibility of improvement on each item of questions was analyzed by Delphi Method. Also interviews with 4 security experts selected from each security agency were conducted to present improvement in each part of problem. The results obtained from the face to face interview with four experts of security-enforcement agency about the role and importance of site activity stage for international conference among several countries are as followings ; First, the system that experienced security-enforcement agents can be selected for the next national security event is needed, by data-basing the security-enforcement agents who were experienced in security event as man power management. Second, the middle-term plan for the introduction of high-tech equipment and joint inspection with relevant security agents are needed for the efficient explosive technical detection. Third, high-tech security equipment could be introduced through the international high-tech security equipment exhibition. Fourth, an anti-terrorism plan should be measured by sharing information through the cooperation with domestic and international intelligence agency. Fifth, public relations should be measured systematically by organization rather than agents' individual public relations. Sixth, political consideration to secure integrative coordination with other agency is needed for security activity, through normal cooperation with fire fighting related agency such as an electric, gas, elevator company. Seventh, a definite press guideline is needed for a convenient news coverage and safety during security event.

• Journal of Intelligence and Information Systems
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• v.22 no.1
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• pp.119-138
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• 2016

Since the Industrial Revolution, which made the mass production and mass distribution of standardized goods possible, machine-made (manufactured) products have accounted for the majority of the market. However, in recent years, the phenomenon of purchasing even more expensive handmade products has become a noticeable trend as consumers have started to acknowledge the value of handmade products, such as the craftsman's commitment, belief in their quality and scarcity, and the sense of self-esteem from having them,. Consumer interest in these handmade products has shown explosive growth and has been coupled with the recent development of three-dimensional (3D) printing technologies. Etsy.com is the world's largest online handmade platform. It is no different from any other online platform; it provides an online market where buyers and sellers virtually meet to share information and transact business. However, Etsy.com is different in that shops within this platform only deal with handmade products in a variety of categories, ranging from jewelry to toys. Since its establishment in 2005, despite being limited to handmade products, Etsy.com has enjoyed rapid growth in membership, transaction volume, and revenue. Most recently in April 2015, it raised funds through an initial public offering (IPO) of more than 1.8 billion USD, which demonstrates the huge potential of online handmade platforms. After the success of Etsy.com, various types of online handmade platforms such as Handmade at Amazon, ArtFire, DaWanda, and Craft is ART have emerged and are now competing with each other, at the same time, which has increased the size of the market. According to Deloitte's 2015 holiday survey on which types of gifts the respondents plan to buy during the holiday season, about 16% of U.S. consumers chose "homemade or craft items (e.g., Etsy purchase)," which was the same rate as those for the computer game and shoes categories. This indicates that consumer interests in online handmade platforms will continue to rise in the future. However, this high interest in the market for handmade products and their platforms has not yet led to academic research. Most extant studies have only focused on machine-made products and intelligent services for them. This indicates a lack of studies on handmade products and their intelligent services on virtual platforms. Therefore, this study used signaling theory and prior research on the effects of sellers' characteristics on their performance (e.g., total sales and price premiums) in the buyer-seller relationship to identify the key influencing e-Image factors (e.g., reputation, size, information sharing, and length of relationship). Then, their impacts on the performance of shops within the online handmade platform were empirically examined; the dataset was collected from Etsy.com through the application of web harvesting technology. The results from the structural equation modeling revealed that the reputation, size, and information sharing have significant effects on the total sales, while the reputation and length of relationship influence price premiums. This study extended the online platform research into online handmade platform research by identifying key influencing e-Image factors on within-platform shop's total sales and price premiums based on signaling theory and then performed a statistical investigation. These findings are expected to be a stepping stone for future studies on intelligent online handmade services as well as handmade products themselves. Furthermore, the findings of the study provide online handmade platform operators with practical guidelines on how to implement intelligent online handmade services. They should also help shop managers build their marketing strategies in a more specific and effective manner by suggesting key influencing e-Image factors. The results of this study should contribute to the vitalization of intelligent online handmade services by providing clues on how to maximize within-platform shops' total sales and price premiums.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.517-534
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• 2021

Hydrogen fuel is emerging as an new energy source to replace fossil fuels in that it can solve environmental pollution problems and reduce energy imbalance and cost. Since hydrogen is eco-friendly but highly explosive, there is a high concern about fire and explosion accidents of hydrogen fueled vehicles. In particular, in semi-enclosed spaces such as tunnels, the risk is predicted to increase. Therefore, this study was conducted on the applicability of the equivalent TNT model and the numerical analysis method to evaluate the hydrogen explosion pressure in the tunnel. In comparison and review of the explosion pressure of 6 equivalent TNT models and Weyandt's experimental results, the Henrych equation was found to be the closest with a deviation of 13.6%. As a result of examining the effect of hydrogen tank capacity (52, 72, 156 L) and tunnel cross-section (40.5, 54, 72, 95 m²) on the explosion pressure using numerical analysis, the explosion pressure wave in the tunnel initially it propagates in a hemispherical shape as in open space. Furthermore, when it passes the certain distance it is transformed a plane wave and propagates at a very gradual decay rate. The Henrych equation agrees well with the numerical analysis results in the section where the explosion pressure is rapidly decreasing, but it is significantly underestimated after the explosion pressure wave is transformed into a plane wave. In case of same hydrogen tank capacity, an explosion pressure decreases as the tunnel cross-sectional area increases, and in case of the same cross-sectional area, the explosion pressure increases by about 2.5 times if the hydrogen tank capacity increases from 52 L to 156 L. As a result of the evaluation of the limiting distance affecting the human body, when a 52 L hydrogen tank explodes, the limiting distance to death was estimated to be about 3 m, and the limiting distance to serious injury was estimated to be 28.5~35.8 m.