• Journal of the Korean Institute of Gas
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• v.24 no.2
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• pp.15-21
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• 2020

Currently, in KS C IEC 60079-10-1, the leakage hole radius of secondary leakage is expressed as a recommendation. Underestimation of leak hole size can lead to underestimation of the calculated values for leak rates, and conservative calculations of leak hole sizes, which are considered for safety reasons, can be overestimated, resulting in an overestimated risk range. This too should be avoided. Therefore, a careful and balanced approach is necessary when estimating the size of leaking holes.Based on this logic, this study examines the stability by grasping the concentration inside the gas box when leaking dangerous substances as a result of experiments based on SEMI S6, an international safety standard applied in the semiconductor industry and The scope of explosion hazardous area was determined by applying the formula of KS C IEC 60079-10-1 according to SEMI F15 leak rate criteria and SEMI S6 leak rate criteria. Based on this, we will examine whether the exhaust performance needs to be improved as an alternative to FAB facilities that are difficult to apply to explosion hazards such as semiconductor industry.

• Fire Science and Engineering
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• v.28 no.5
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• pp.58-63
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• 2014

Fire-resistance paints are supposed to become intumescent and diminish heat transfer along the steel frames in case of a fire. If unsatisfactory fire-resistance paints which do not satisfy their standard specification are used, it may result in a severe disaster. Because satisfactory fire-resistance paints are hardly discriminated from the unsatisfactory ones by a simple visual inspection, more reliable and convenient onsite evaluation methods are necessary. Here we report the preliminary study result on the fire safety testing method for fire-resistance paints using an X-ray analysis method. It was found that the existence and quantity of effective constituents in fire-resistance paints can be detected by the X-ray analysis method. X-ray fluorescence (XRF) analyses showed that P and Cl elements are much more enriched in fire-resistance paints, compared to normal paints. X-ray diffraction (XRD) analyses showed that ammonium polyphosphate is present as the main crystalline material in fire-resistance paints, but absent in normal paints. The X-ray analysis method is expected to be used for the onsite inspection of fire-resistance paints with the upcoming availability of portable XRF and XRD instruments.

• Journal of the Korea Institute of Building Construction
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• v.10 no.6
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• pp.127-135
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• 2010

As logistics facilities have a high ceiling height, simple structure, and the need for a quick return on investment, it is usually essential to advance the construction schedule of such facilities. Accordingly, PC structures, which require less labor, cost and schedule, can be more competitive than RC structures. However, most construction companies in Korea are familiar with RC structure design, have negative perceptions regarding PC structures, and do not sufficiently adopt new construction techniques. The structure that this research features has 110 columns that are 14 m high and are built to the same specification, and applying an RC design to the structure will lead to issues related to constructibility, economic viability, project duration and safety. Therefore, this study intends to feature PC design as an alternative to the RC warehouse design, and perform a comparative analysis of the reduction in labor, cost and construction schedule to highlight benefits. The research outcomes herein will provide inputs to subsequent studies on new construction strategies to advance the construction schedule, improve quality and constructibility, enhance safety and save costs.

• Journal of the Society of Disaster Information
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• v.13 no.3
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• pp.305-312
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• 2017

In our society, the advanced, advanced, and information industries have continued to grow and now live in the era of the fourth industrial revolution. As the industry develops, the load of the users has also increased so much that it is deepened by the energy shortage phenomenon and the construction of additional energy facilities is required. Therefore, energy plant construction work is being actively carried out in the coastal area. In particular, it is common to build a plant in the ground by filling the coast with soil in other regions, reflecting the fact that Korea is lacking in the country when constructing power plants, gas and petrochemical plants. Current domestic grounding designs are designed or constructed to suit only the use of grounding resistors based on the electrical equipment design technical standards. However, in the case of a plant facility constructed in the untested buried soil, when the lightning current and the abnormal current are inputted, the facility operator or the user due to the elevation of the ground potential is seriously exposed to the risk of electric shock disaster. In this paper, we analyze the ground resistivity of the landfilled soil and use a computer program (CDEGS) based on KS C IEC 61936-1, We analyze the contact voltage and stratification voltage and propose a grounding design optimized for plant installation.

• Journal of Food Hygiene and Safety
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• v.29 no.1
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• pp.16-20
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• 2014

The prevalence of Bacillus cereus was determined in salad and Kimbab obtained from commercial retailers. Among the 100 salad samples analyzed, 54 samples were negative for B. cereus, whereas the bacterial count was < 10 colony forming units (CFU)/g in 8 samples, < 100 CFU/g in 25 samples, < 1,000 CFU/g in 11 samples, and > 1,000 CFU/g in 2 samples. The mean (standard deviation) was 1.18 log CFU/g (${\pm}0.71$ log CFU/g). In Kimbab, B. cereus was isolated from 20 samples; the mean bacterial count was 1.01 log CFU/g (${\pm}0.71$ log CFU/g). On the basis of the monitoring data, a statistical sampling plan was determined with the NEW sampleplan program (ICMSF), which was used as an analytical tool. To identify the most suitable sampling plan, the microbial limits (m, M) and the maximum allowable number of sample units yielding unsatisfactory test results (c) were varied, but the number of samples units, n = 5, was fixed. Sampling plans showing an acceptable probability (Pa) over 0.95 were considered suitable. Two plans (A and B) were finally suggested. Parameters for plan A are n = 5, c = 0, m = 1,000, and M = 10,000 and for plan B are n = 5, c = 2, m = 100, and M = 1,000. Interestingly, the latter plan was identical to the microbial sampling plan used in New Zealand. Thus, it was concluded that the suggested plan can be used as a sampling plan that is in line with international standards.

• Journal of Food Hygiene and Safety
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• v.27 no.4
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• pp.456-460
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• 2012

This study was carried out as a survey on the level of lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg) in 5 items of agricultural products (lettuce, pumpkin, head lettuce, cabbage and crown daisy) for which safety guidelines are not yet established in Korea. The 407 samples were collected from local markets in 9 regional places and the levels of metals were measured by ICP-MS and mercury analyzer. The average levels of Pb, Cd, As and Hg were 0.026, 0.018, 0.008 and 0.003 mg/kg for lettuce, 0.002, 0.001, 0.001 and 0.0006 mg/kg for pumpkin, 0.002, 0.005, 0.001 and 0.0005 mg/kg for head lettuce, 0.001, 0.002, 0.0002 and 0.0006 mg/kg for cabbage and 0.022, 0.014, 0.006 and 0.004 mg/kg for crown daisy. For risk assessment, the daily dietary exposures of Pb, Cd and Hg by intake of these agricultural products were calculated and compared with PTWI (provisional tolerable weekly intake) established by JECFA. The daily dietary exposure of heavy metals by intake of these agricultural products were 0.13, 0.56 and 0.09% of PTWI, respectively. These monitoring results will be utilized as fundamental data for the establishment of Korean standards of Pb, Cd, As and Hg in 5 items of agricultural products and valuable source for DB construction for science-based safety control of heavy metals in foods including agricultural products.

• Journal of Applied Biological Chemistry
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• v.61 no.4
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• pp.391-395
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• 2018

There is an increasing concern over arsenic (As) contamination of paddy soil and rice with regard to food safety. This study was conducted to investigate total and inorganic As concentration in one hundred husked and polished rice samples collected at the non-contaminated paddy soil in Korea. Arsenic species in rice samples were extracted using 1% nitric acid ($HNO_3$) with a microwave oven and were measured using high performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry. Mean concentrations of total As in husked rice and polished rice were 0.18 and $0.11mg\;kg^{-1}$, respectively. Also, average inorganic As concentrations in husked rice and polished rice were 0.11 and $0.07mg\;kg^{-1}$, respectively. These levels are lower than the standard guideline value 0.35 and $0.2mg\;kg^{-1}$ for inorganic As in husked and polished rice recommended by Codex Committee on Contaminants in Foods and Ministry of Food and Drug Safety, respectively. The mean of the inorganic As ratio for the total amount of As was 0.65 and 0.67 for husked rice and polished rice, respectively, and the range was from 0.08 to 1.0. For health risk assessment, the average value of cancer risk probability was $9.24{\times}10^{-5}$ and ranged from $2.30{\times}10^{-5}$ to $1.90{\times}10^{-5}$. Therefore, human exposure to As through dietary intake of surveyed rice samples might considered to be a low health risk.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.605-611
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• 2019

The fuel sloshing due to the rapid manoeuvre of the aircraft causes significant loads on internal components, which may break components or piping. In particular, a significant load is applied to the joint of the external fuel tank by sloshing movement, which may affect the safety of the aircraft when the joint of the external fuel tank is damaged. Therefore, in order to improve the survivability of aircraft and crew members, the design of external fuel tanks, and joints should be performed after evaluating the sloshing load through a numerical analysis of the fuel sloshing conditions. In this paper, a numerical analysis was performed on the sloshing test of the external fuel tank for rotorcraft. ALE (Arbitrary Lagrangian Eulerian) technique was used, and the test conditions specified in the U.S. Military Specification (MIL-DTL-27422D) was applied as the conditions for numerical analysis. As a result of the numerical analysis, the load on the joint of the external fuel tank was calculated. Moreover, the effects of sloshing movement on structural soundness were assessed through analysis of stress levels and margin of safety on metal fittings and composite containers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.777-783
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• 2021

Aircraft are affected by various vibrations during maneuvering. These vibrations may have a fatal effect on the survival of aircraft in some cases, so the safety of components applied to the aircraft should be proven against various vibrations through random vibration analysis. In this study, the structural robustness of an external fuel tank and pylon for military aircraft was evaluated under random vibration conditions using commercial software, MSC Random. In the random vibration analysis, a frequency response analysis was performed by imposing a unit load on the boundary condition point, and then excitation was performed with a PSD profile. In this process, the required mode data was extracted through a modal analysis method. In addition, the random vibration profile specified in the US Defense Environment Standard was applied as random vibration conditions, and the PSD profile given in units of G's was converted into units of gravitational acceleration. As a result of the numerical analysis, we evaluated the structural robustness of the external fuel tank and pylon by identifying the safety margins of beam elements, shell elements, and solid elements in a numerical model for random vibration in the x, y, and z directions.

• Journal of Food Hygiene and Safety
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• v.35 no.6
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• pp.552-560
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• 2020

Listeria monocytogenes is a highly pathogenic gram-positive bacterium that is easily isolated from cheese, meat, processed meat products, and smoked salmon. A zero-tolerance (n=5, c=0, m=0/25 g) criteria has been applied for L. monocytogenes in cheese meaning that L. monocytogenes must not be detected in any 25 g of samples. However, there was a lack of scientific information behind this criteria. Therefore, in this study, we conducted a risk assessment based on literature reviews to provide scientific information supporting the baseline and to raise public awareness of L. monocytogenes foodborne illness. Quantitative risk assessment of L. monocytogenes for cheese was conducted using the following steps: exposure assessment, hazard characterization, and risk characterization. As a result, the initial contamination level of L. monocytogenes was -4.0 Log CFU/g in cheese. The consumption frequency of cheese was 11.8%, and the appropriate probability distribution for amount of cheese consumed was a Lognormal distribution with an average of 32.5 g. In conclusion, the mean of probabilities of foodborne illness caused by the consumption of cheese was 5.09×10-7 in the healthy population and 4.32×10-6 in the susceptible population. Consumption frequency has the biggest effect on the probability of foodborne illness, but storage and transportation times have also been found to affect the probability of foodborne illness; thus, management of the distribution environment should be considered important. Through this risk assessment, scientific data to support the criteria for L. monocytogenes in cheese could be obtained. In addition, we recommend that further risk assessment studies of L. monocytogenes in various foods be conducted in the future.