• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.4
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• pp.107-112
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• 2007

The vibration generated on shipboard is very important because it greatly affects on the comfortable mind of passenger and working conditions of crews. Shipboard vibration is closely concerned with the development of propulsion method and the type of main engine to decide speed of ship. To make the propulsion power, the main engine of ship have continuous explosion process in engine room, so the shipboard vibration is generated. The shipboard vibration causes the physiological and psychological damages to human body. In the case of the human body exposed to the shipboard vibration, the evaluation of human exposure to whole-body vibration is prescribed in ISO 6954 : 2000(E). In this paper, to evaluate the shipboard working environment, two kinds of vibration levels onboard ship were measured and compared with one another between engine rooms, engine control rooms and wheel house by the regulation of ISO 6954 : 2000(E).

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.139-144
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• 2007

The vibration generated on shipboard is very important because it is greatly affect on the comfortable mind of passenger and working conditions et crews. Shipboard vibration is closely concerned with the development of propulsion method tint is main engine to decide speed of ship. To make the propulsion power, the main engine of ship engine room have continuous explosion process, so the shipboard vibration is generated The physiological damage and psychological damage of human body have caused by the vibration et shipboard In the case of the human body is exposed to the shipboard vibration, the evaluation of human exposure to whole-body vibration is prescribed in ISO 6954: 2000(E). In this paper, to evaluate the shipboard working environment, the vibration levels of two kinds of ship onboard were measured and compared with engine rooms, engine control rooms and bridges by the regulation of ISO 6954: 2000(E)

• Journal of the Korean Institute of Gas
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• v.26 no.5
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• pp.22-27
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• 2022

Atomic Layer Deposition (ALD) is a facility that deposits an atomic layer on a wafer by causing a chemical reaction after decomposition using heat or plasma by inputting two or more gases during the semiconductor process. The main gas used at this time is NH₃ (Ammonia). NH₃ has a relatively narrow explosive range with an upper limit (UFL) of 33.6% and a lower limit (LEL) of 15%, but it can explode if a large amount suddenly gathers in one place. It is Velocity and fatal if inhaled or in contact with the skin. NH₃ (Ammonia) of ALD (Atomic Layer Deposition) facility is supplied to the chamber through the gas inlet and discharged after the reaction.

• 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.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.610-619
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• 2022

Hydrogen is emerging as an alternative fuel for eco-friendly ships because it reacts with oxygen to produce electrical energy and only water as a by-product. However, unlike regular fossil fuels, hydrogen has a material with a high risk of explosion due to its low ignition point and high flammability range. In order to safely use hydrogen in ships, it is an essential task to study the flow characteristics of hydrogen leakage and diffusion need to be studied. In this study, a numerical analysis was performed on the effect of leakage, ventilation, etc. on ventilation performance when hydrogen leaks in an enclosed space such as inside a ship. ANSYS CFX ver 18.1, a commercial CFD software, was used for numerical analysis. The leakage rate was changed to 1 q, 2 q, and 3 q at 1 q = 1 g/s, the ventilation rate was changed to 1 Q, 2 Q and 3 Q at 1 Q = 0.91 m/s, and the ventilation method was changed to type I, type II, type III to analyze the ventilation performance was analyzed. As the amount of leakage increased from 1 q to 3 q, the HMF in the storage room was about 2.4 to 3.0 times higher. Furthermore, the amount of ventilation to reduce the risk of explosion should be at least 2 Q, and it was established that type III was the most suitable method for the formation of negative pressure inside the hydrogen tank storage room.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.2
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• pp.238-245
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• 2014

Objectives: It was known that workers in synthetic leather company are mainly co-exposed to dimethylformamide(DMF) with methyl ethyl ketone(MEK) or toluene(TOL) instead of a single dimethylformamide. This study was examined to the physico-chemical properties in single DMF and binary mixture DMF with MEK or TOL. Materials: Physico-chemical properties were measured by Korean and American Standard Test Methods. Results: Boiling point, specific gravity and flash point in single DMF were significantly higher than binary mixture DMF with MEK or TOL and such difference was dependent on the mixing ratio of MEK and TOL, and low explosion limit in binary mixture DMF with TOL was only significantly lower than single DMF. However, Reid vapor pressure had significantly higher in binary mixture DMF with MEK or TOL compared with single DMF. Conclusions: Our results demonstrate that the binary mixture DMF with MEK or TOL synergistically increases volatilization of DMF. It was concluded that the interaction between DMF and MEK and/or TOL might play a key role in the volatilization process of DMF under environmental conditions of workplace.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.11
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• pp.9-17
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• 2000

A sensor array with 10 discrete sensors integrated on a substrate was developed for discriminating the kinds and quantities of explosive gases. The sensor array consisted of 10 oxide semiconductor gas sensors with $SnO_2$ as base material and had broad sensitivity to specific gas. The sensor array was designed with uniform thermal distribution and had also high sensitivity and reproductivity to low gas concentration through nano-sized sensing materials with different additives. By using the sensitivity signal of the sensor array at $400^{\circ}C$, we could reliably discriminate the kinds and quantities of explosive gases like butane, propane and methane under the lower explosion limit through the principal component analysis (PCA) method.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3637-3641
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• 2014

In this study, we analyzed the toxicity of mixtures of dimethylformamide (DMF) and methyl ethyl ketone (MEK) or DMF and toluene (TOL) and predicted their toxicity using quantitative structure-activity relationships (QSAR). A QSAR model for single substances and mixtures was analyzed using multiple linear regression (MLR) by taking into account the statistical parameters between the observed and predicted $EC_{50}$. After preprocessing, the best subsets of descriptors in the learning methods were determined using a 5-fold cross-validation method. Significant differences in physico-chemical properties such as boiling point (BP), specific gravity (SG), Reid vapor pressure (rVP), flash point (FP), low explosion limit (LEL), and octanol/water partition coefficient (Pow) were observed between the single substances and the mixtures. The $EC_{50}$ of the mixture of DMF and TOL was significantly lower than that of DMF. The mixture toxicity was directly related to the mixing ratio of TOL and MEK (MLR $EC_{50}$ equation = $1.76997-1.12249{\times}TOL+1.21045{\times}MEK$), as well as to SG, VP, and LEL (MLR equation $EC_{50}=15.44388-19.84549{\times}SG+0.05091{\times}VP+1.85846{\times}LEL$). These results show that QSAR-based models can be used to quantitatively predict the toxicity of mixtures used in manufacturing industries.

• Journal of Sensor Science and Technology
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• v.10 no.2
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• pp.108-117
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• 2001

A sensor array with 10 discrete sensors integrated on a substrate w3s developed for discriminating the kinds and quantities of inflammable gases, like butane, propane, methane, LPG, carbon monoxide. The sensor array consisted of 10 metal oxide semiconductor gas sensors using the nano-sized $SnO_2$ as base material and had differentiated sensitivity patterns to specific gas. The sensor array was designed with uniform thermal distribution and had also high sensitivity and good reproductivity to low gas concentration through nano-sized sensing materials with different additives. By using the sensing patterns of the sensor array at $400^{\circ}C$, we could reliably discriminate the kinds and quantities of the tested inflammable gases under the lower explosion limit through the principal component analysis(PCA).

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.1-7
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• 2001

This paper presents a 'consequence analysis' for vapor cloud explosions caused by heavy gas leakages from commercially used storage tanks at petrochemical plants. Particularly, this paper emphasizes on evaluating the results of various vapor cloud explosion accidents from Butane storage tanks. Also this paper analyses the impact of variables on the accidents in order to acquire the optimum conditions for variables. $SuperChems^{TM}$ Professional Edition was applied to analyse the impact (If atmospheric and other variables in the situation where vapor cloud continuously disperses from the ground level. Under the assumption that practical operating conditions are selected as a standard condition, and Butane leaks from the storage tank for 15 minutes, the results show that the maximum distance of LFL (Lower Flammable Limit) was 52 meters and overpressure by the vapor cloud explosion was 1 psi at 128.2 meters. It is observed that the impact of the variables on accidental Butane storage tank leakage mainly varied upon atmospheric stability, wind velocity, pipe line size, visible length, etc., and changes in the simulation result occurred as the variables varied. The maximum distance of the LFL (Lower Flammable Limit) increased as the visible length became shorter, the size of the leak became larger, the wind velocity was decreased, and the climatic conditions became more stable. Thus, by analysing the variables that influence the simulation results of explosions of Butane storage tanks containing heavy gases, I am presenting the most appropriate method for 'consequence analysis' and the selection of standards for suitable values of variables, to obtain the most optimal conditions for the best results.