• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.39-44
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• 2016

This study was to investigate the characteristics of combustion toxic gases of pinus rigida specimens treated with chemical additives such as pyrophosphoric acid (PP)/ammonuium ion ($NH_4{^+}$), methylenepiperazinomethyl-bis-phosphonic acid (PIPEABP) and $PIPEABP/NH_4{^+}$. Each pinus rigida plates was painted in three times with 15 wt% of each chemical additives in the aqueous solution. After drying these specimens at room temperature, the production of combustion gases and smoke was examined by the cone calorimeter (ISO 5660-1). As a result, the peak mass loss rate time (PMLR time) treated with chemicals was delayed upto 10.5~47.4% compared to that of using untreated specimen. In addition, the peak production of carbon monoxide ($CO\;_{peak}$) of 32.1~71.4% and total smoke release rate (TSRR) of 15.6~43.6% for test pieces treated with the chemical additive were higher than that of using the virgin plate. In particular, for the specimens treated with the chemical additive, the rate of smoke release (RSR) 29.4~41.5% was obtained higher than that of untreated plate except the specimen treated with $PP/4NH_4{^+}$. It can thus be concluded that the treatment using the chemical additive could partially increase the combustion-retardation properties of the species when compared to those of the virgin plate.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.377-384
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• 2014

Recently, the trend toward larger architectural structures continues and accelerates demand for Ultra High Strength Concrete (UHSC) which satisfies structural performance. However, UHSC has weakness in fire and the performance tests are required. In this paper, the change of mechanical properties of 100 MPa grade UHSC exposed to high temperatures ($20^{\circ}C{\sim}800^{\circ}C$) was observed to develop high temperature material model of UHSC: residual compressive strength, modulus of elasticity, property of stress-strain on monotonous loading and property of stress-strain on cyclic loading. In addition, TG/DTA and SEM Images analyses were performed to investigate chemical and physical characteristics of UHSC, and the results of this research were compared with those of previous studies. As a result, UHSC at the heating temperature of $300^{\circ}C$ showed a sharp decrease of residual compressive strength and modulus of elasticity. And It was shown that UHSC had a plastic behavior at more than $400^{\circ}C$ on the cyclic loading and revealed a same tendency in both monotonous and cyclic loading of all heating temperatures. In addition, through TG/DTA and SEM images analyses compared with those from previous studies, it was shown that the deterioration of concrete inner tissue, water evaporation and chemical reaction caused the decrease of residual compressive strength and modulus of elasticity.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.413-418
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• 2018

Cypress woods treated individually with boric acid (BA4), ammonium pentaborate (APB4), or BA4/APB4 additives were examined for combustion gases. Each of the specimens was painted with a 4 wt% solution of boron compounds three times. Dried at room temperature, the combustion gas was analyzed using a cone calorimeter (ISO 5660-1). Consequently, the second maximum oxygen consumption rate of the specimen treated with boron compounds was 0.1067 to 0.1246 g/s, which was 5.3 to 18.9%, respectively lower than that of the blank specimen. The specific extinction area of specimens treated with BA4 and APB4 was also 2.0 to 19.0% lower, respectively. However, treated with BA4/APB4 showed 21.2% higher than that of the blank specimen. The maximum carbon monoxide concentration of the specimens with boron compounds was reduced by 0 to 25%. It was estimated to be 1.6 to 2.2 times higher than the permissible exposure limits by Occupational Safety and Health Administration (OSHA), indicating a fatal toxicity. The boron compounds were effective in reducing carbon monoxide, but didn't meet the OSHA limit. The boron compound inhibited the burning behavior of the cypress wood, which suppressed the second maximum oxygen consumption rate by 5.3 to 18.9% and the maximum carbon monoxide generation by 0 to 25%.

• Polymer(Korea)
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• v.25 no.1
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• pp.142-150
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• 2001

Until now rubber industry field has used organic solvent base adhesive, there was always existed a fire risk, variety of quality and harmfulness of human body. To solve this problem we were developed a new adhesive that was maked by raw materials of hydrocarbon series which has the properties of nonvolatile and high flash point. Because of this new adhesive has the properties of nonvolatile and non-harmfulness to the human body, we expected to solve the problems of a fire hazard and the pollution of the environmental. Instead of the rubber binder that is used to a present adhesive, the new idea is adopted in a new type of adhesive. Nonvolatile solvent penetrated to the rubber surface and caused the swelling in rubber surface and as a result of this action, it has the self-adhesive power. In comparision with the present adhesive a new type of adhesive remarkably improved the maintenance time of adhesion and the durability of this adhesive showed similar aspect. Because it did not exhibit a drop of physical properties of rubber which was caused by swelling effect, we estimate that new type adhesive are very stable and not reacted to several rubber additives. While present adhesive appear the crack at cutting surface of curing rubber that caused by gas, new type adhesive not exist these crack.

• Journal of the Mineralogical Society of Korea
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• v.29 no.4
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• pp.179-190
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• 2016

X-ray diffraction analysis, chromaticity measurement, execution and evaluation by Dancheong artisan, accelerated weathering test, and fire resistance test were conducted to test the applicability as a Dancheong pigment raw materials of Korean low grade kaolin in cultural properties. The ores that feldspar rich and composed of fine particles (< $38.1{\mu}m$) showing advantageous for the inherent purpose of the white pigment than that of high grade kaolin. And the test of whiteness, concealment force, outdoor exposure durability and fire resistance shows similar or better result than existing products (Hobun and Sanhwa jidang). In conclusion, it is expected that the use of fine feldspar rich white soil and low-grade kaolin can be used as a white pigment raw materials which have similar to better material properties and economic efficiency than existing products.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.17 no.2
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• pp.111-119
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• 2007

Firemen are directly exposed to various harmful chemicals, physical factors and mental stress during rescue and fire-fighting. In fire extinguishing, unstable posture, poisonous gas, dust, high temperature and heavy equipments are possible hazardous factors. The alertness for emergency, shift work, job strain and stress are also possibly hazardous. Therefore, this study aimed to investigate the prevalence of musculo-skeletal symptoms and job stress and to determine risk factors in firemen. This study was carried out in a group of 226 firemen in Busan City, Korea. Standardized Nordic Questionnaire was used to investigate the prevalence of musculo-skeletal symptoms and Psycho-social Well-being Index (abbreviated PWI) was used to investigate the prevalence of job stress. General and occupational characteristics were included education, marital status, alcohol and smoking history, working duration, and work shift system. Body mass index (BMI) scores were calculated by physical examination including height and weight. Concerning musculo-skeletal complaints, the commonest site was neck, and shoulder, lower back, upper back were the next. Complaint site above one area of body was about 80%. From multiple logistic regression analysis, working duration was significant variable in musculo-skeletal symptoms. Odds ratio were 15.4 in working duration. About 16.8% was high risk stress group. From multiple logistic regression analysis, shift work and alcohol drinking were significant variables in PWI scores. Odds ratios were 2.25 in shift work. Accordingly, interventions are needed for health promotion of long term and shift worker.

• Journal of Korean Society of Disaster and Security
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• v.10 no.1
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• pp.85-90
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• 2017

The purpose of this study is to investigate the effect of vertical and horizontal refraction on the lower part of the power supply and control system of various facilities and machinery that use electricity, so that the power distribution system, which is an important electric facility installed in buildings and public facilities, Type earthquake resistant pads to protect the substructure and prevent short-circuiting on the upper part of the system. The GR-63-CORE (Scale 8.3 class) It is earthquake disaster prevention and disaster prevention technology that satisfies seismic performance. As a research result, it is possible to protect the electricity and communication infrastructure, which can contribute to shortening the time for recovering the electric facilities to the normal state in case of an earthquake, and preventing the fire caused by the destruction of the electricity supply facility in case of an earthquake. As a result, it is possible to minimize the spread of fire that occurs when a large-scale earthquake occurs and to minimize the damage of people and damage to property, and it can contribute to the securing of electric infrastructure that enables citizens to quickly recover to daily life even after suffering a major earthquake. In addition, the technology can be applied to ensure the seismic resistance of the equipment in the communication and computer room, and it can be applied to various fields where the facility function can be stopped due to the shaking of the earthquake base.

• Journal of architectural history
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• v.24 no.5
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• pp.33-40
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• 2015

The present study is aimed to reconsider the time of installation and the purpose of the square footstone located at the center of the wooden pagoda in Hwangnyongsa Temple, based on related precedent studies. Precedent studies are divided into two streams of assertions: one is that the square footstone was to support the major pillars at the time of building and the other is that it was installed to store Buddhist reliquaries inside the central foundation stone after the wood pagoda burnt down in the Invasion of Mongol. Summarizing the grounds with which the precedent studies support their assertions, they are the relation with Gaseopbul Yeonjwaseok, the emerging time of the square footstone, repairing work at the level of reconstruction, additional enshrinement of general Buddhist reliquaries and so on. The present study reviewed the key grounds suggested in the previous studies regarding the square footstone. First, it was determined that the square footstone has nothing to do with Gaseopbul Yeonjwaseok, after looking into the timings of appearance, condition and shape in literatures. Rather, it was assumed that Gaseopbul Yeonjwaseok resembles a stone column. Next, the square footstone is assumed to be installed after the 4th year of King Kwangjong's rule because the wood pagoda was lost in fire in the 4th year of Kwangjong's rule and it had been left alone for 68 years until the repair work finished in the 13th year of King Hyunjong. It is assumed that repair works at the level of reconstruction had been twice in total, say, once during King Kyungmun and Hyunjong, respectively. Next, looking into the establishment of the general Buddhist reliquaries and the repair work during King Kyungmun, it was not common then to enshrine additional Buddhist reliquaries when repair work progressed and so there was not an additional enshrinement of Buddhist reliquaries after King Kyungmun. However, it is hard to decide that there was no repair work at the level of reconstruction at that time. Last, we can find a similar case to the square footstone of the wood pagoda in Hwangnyongsa Temple in the copper pagoda in Japanese Yaksasa Temple. In conclusion, it is assumed that the wooden pagoda in Hwangnyongsa Temple was lost to the fire in the 4th year of King Kwangjong's rule and thus the square footstone had been used as Jinho stone to protect Buddhist reliquaries and used as a propping stone for the major pillars after King Hyungjong.

• Journal of the Korean Society of Safety
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• v.37 no.4
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• pp.120-128
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• 2022

Printed circuit boards (PCBs) are a basic component in the electronics industry and are widely used in nearly all electronic products, such as mobile phones, tablet computers, and digital cameras, as well as in electric equipment. PCB manufacturing involves the use of many chemicals and chemical processes and therefore has more risks than other manufacturing sectors. This study aims to identify the causes of possible accidents during PCB manufacturing through risk assessment, develop and implement safety measures, and evaluate the effectiveness of these measures. Note that the safety measures developed to mitigate the risks of a certain process were also implemented for other similar processes. The risk assessments conducted over seven years, from 2015 to 2021, at a PCB manufacturing company identified 361 hazardous processes. Between 2016 and 2019, 41-56 hazardous processes were identified per year; such processes decreased to fewer than 20 per year after 2020. Application of the risk assessment results to the improvement of the hazardous processes with the similar characteristics seems to be effective in decreasing the risks. Equipment-related factors such as lack of appropriate maintenance, low work standards, and defective protection devices were responsible for 59.8% of all possible accidents. Because PCB manufacturing involves many chemicals, skin contact with hazardous substances, electric shock, fire, and explosion were the most common types of possible accidents (81.7%). In total, 505 safety measures were implemented, including 157 related to purchase and improvement of equipment and devices for safety (31.1%), 147 related to the installation/modification of fire prevention facilities (29.1%), and 69 related to the use of standard electrical appliances (13.7%). Risk assessment conducted after implementing the safety measures showed that these measures significantly decreased risk; 247 processes (68.4%) had a risk level of 3, corresponding to "very low," and 114 processes (31.6%) showed a risk level of 4, corresponding to "low." In particular, risk assessment of 104 processes with risk scores of 12 and 10 other processes with risk score of 16 showed that the risk decreased to 4 after implementing the safety measures. Thus, implementing these measures in similar manufacturing sectors that involve chemical processes can mitigate risk.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.280-291
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• 2023

Purpose: As fire accidents happen at the production and storage sites of superabsorbent polymers for convenience of daily life, an experimental study was conducted to secure basic data to establish practical preventive measures against them. Method: The sample container (20cm width × 20cm length) was made into a rectangular cuboid with the heights of 3cm, 5cm, 7cm, and 14cm, respectively, to allow access to the infinite flat plane. The front and back of the container were covered with a 300-mesh stainless steel mesh for one-dimensional heat transfer. The sample container was placed in the center of the thermostatic bath, which was heated to a predetermined temperature by setting the thermostat program in advance, and it was determined to be 'ignited' when the central temperature of the sample rose by more than 20℃ above the set temperature, and "unignited" when it was maintained at an approximate value of the set temperature. Result: The critical autoignition temperature was calculated to be 217.5℃ when the height of the sample container was 3 cm, 212.5℃ when it was 5 cm, 202.5℃ when it was 7cm, and 187.5℃ when it was 14cm. The ignition induction time to reach the maximum temperature was 34hours for 3cm, 76hours for 5cm, 143hours for 7cm, and 318hours for 14cm. Conclusion: ① As the size of the container increased, the autoignition temperature decreased and the induction time to reach the maximum temperature increased. ② An apparent activation energy was calculated to be 44.92kcal/mol, with a correlation of 96.93%.