• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.11
• /
• pp.634-640
• /
• 2017

Toxicity and fate assessment is necessary in the evaluation of the environmental, health and safety risks of engineered nanomaaterials (ENMs). Therefore, in order to ensure the reproducibility, reliability and relevance of ENMs toxicity results, stable and monomodal dispersion protocols in toxicity test media are needed. Zinc oxide nanoparticles (nZnO) are widely used in various products such as cosmetic products, paper, paints etc. In this study, nZnO dispersions in ecotoxicity test media were produced by following a series of steps of modified National Institute of Standards and Technology (NIST) Special publication 1200-5. In addition, natural organic matter (humic acid (HA)) was used as a stabilizing agent to disperse nZnO in the test media. The hydrodynamic diameters (HDD) of the nZnO in dispersion ranged between 150 and 200 nm according to the dynamic light scattering (DLS) measurement. Based on these dispersions in ecotoxicity test using ecological species (Oryzias latipes, Daphnia magna, Pseudokirchneriella subcapitata and Chironomusus riparius), dispersion protocol was found to have a considerable potential in ecotoxicity test of ENMs.

• Communications for Statistical Applications and Methods
• /
• v.20 no.4
• /
• pp.321-327
• /
• 2013

Bayesian and empirical Bayesian methods have become quite popular in the theory and practice of statistics. However, the objective is to often produce an ensemble of parameter estimates as well as to produce the histogram of the estimates. For example, in insurance pricing, the accurate point estimates of risk for each group is necessary and also proper dispersion estimation should be considered. Well-known Bayes estimates (which is the posterior means under quadratic loss) are underdispersed as an estimate of the histogram of parameters. The adjustment of Bayes estimates to correct this problem is known as constrained Bayes estimators, which are matching the first two empirical moments. In this paper, we propose a way to apply the constrained Bayes estimators in insurance pricing, which is required to estimate accurately both location and dispersion. Also, the benefit of the constrained Bayes estimates will be discussed by analyzing real insurance accident data.

• Journal of Korean Society for Atmospheric Environment
• /
• v.22 no.1
• /
• pp.73-84
• /
• 2006

Hazardous Air Pollutants (HAPs) are characterized by being relatively heavier and denser than that of ambient air due to the various reasons such as higher molecular weight, low temperature and other complicated chemical transformations (Witlox, 1994). In an effort to investigate transport and diffusion from instantaneous emission of heavy gas, Lagrangian Particle Dispersion Model (LPDM) coupled with the RAMS output was employed. Both deposition process and buoyancy term were added on the atmospheric diffusion equations of LPDM, and the locations and concentrations of dense gas particle released from instantaneous single point source (emitting initially for 10 minutes only) were analyzed. The result overall shows that adding deposition process and buoyancy terms on the diffusion equation of LPDM has very small but detectable effect on the vertical and horizontal distribution of Lagrangian particles that especially transported for a fairly long traveling time. Also the slumping of dense gas can be found to be ignored horizontally compared to the advection by the horizontal wind suggesting that it was essential to couple the Lagrangian particle dispersion model coupled with the RAMS model in order to explain the dispersion of HAPs more accurately. However, during the initial time of instantaneous emission, buoyancy term play an important role on the vertical locations of dense particles for near surface atmosphere and around source area, indicating the importance of densities of HAPs in the beginning stage or short duration for the risk assessment of HAPs or management of heavy vapors during the explosive accidents.

• Journal of the Korean Institute of Gas
• /
• v.16 no.4
• /
• pp.44-51
• /
• 2012

It is more important to realize safety management, medium-large accident prevention and risk prediction as accident of industry facilities can generate enormous physical and human damage because most energy plant might handle toxic substance. Especially, atmospheric dispersion system, which is able to simulate situation, have been used for release accident of toxic substance since the accident can show different of dispersion range and velocity according to release material, storage facility and atmospheric status. However those systems have been used generally in design step of industry facility and are difficult to deal with release accident quickly. Although some researches and cases have been studied for using real-time atmospheric information, there are insufficient system for processing quickly release accident. This paper aims to develop real-time smart atmospheric dispersion system that can deal with release accident quickly by enhancing distinct characteristics and efficiency of energy plant, and select release time and area using intelligent algorithm as accident prevention type.

• Korean Journal of Biological Psychiatry
• /
• v.19 no.1
• /
• pp.38-44
• /
• 2012

Objectives : QT interval prolongation and dispersion known as indicators of an increased risk for ventricular arrhythmias and sudden death have been reported to be prolonged in patients with anorexia nervosa. The aims of this study were to compare conduction abnormalities in Korean patients with anorexia nervosa and bulimia nervosa, and to examine its relation with clinical and laboratory factors. Methods : We retrospectively examined 45 women with anorexia nervosa and 75 women with bulimia nervosa who were assessed by 12-lead electrocardiogram at baseline. QT interval and corrected QT interval, QT dispersion of the difference between the longest and shortest QT intervals, and abnormal U wave were measured for conduction abnormalities. Results : QT interval was significantly longer in patients with anorexia nervosa compared with those with bulimia nervosa. There were no differences in QTc (Corrected QT), QTd (QT dispersion) and abnormal U wave between patients with anorexia nervosa and those with bulimia nervosa. QTd was significantly correlated with the lowest ever lifetime body mass index ($kg/m^2$) as well as the serum amylase level in patients with anorexia nervosa. Conclusions : These results suggest some conduction abnormalities reported in patients with anorexia nervosa are also found in patients with bulimia nervosa. It appears that severity of weight loss and purging behavior could affect the cardiac arrhythmia in patients with eating disorders. Appropriate attention should be paid to cardiac involvement in patients with eating disorders.

• Journal of Korean Society of Transportation
• /
• v.31 no.2
• /
• pp.69-79
• /
• 2013

This study suggests a specific methodology to analyze how emission impacts on regional emission concentrations in accordance with the change of weather conditions, and the need of its application. The suggested methodology was applied to a transportation network of Pochun area in Gyenggido as an example. The methodology contains two types of analytical models; 1) dispersion analysis based on emission from traffic, and 2) dispersion analysis based on the combination between emission from traffic and existing emission in the air. By doing so, it is expected that the comprehensive influence of emission on traffic network and its surrounding areas can be identified. In addition, it might be useful for us to apply environmental risk assessment based on the effect of emission on the people.

• Explosives and Blasting
• /
• v.29 no.2
• /
• pp.59-66
• /
• 2011

A variety of risks caused by natural, technological and biological hazards threaten a business continuity of an organization. Business continuity is very important issue for all organizations and its proper management may control success and failure of an organization. Business continuity plan (BCP) may be defined as a management process which provides a business continuity. BCP includes risk management, operational continuity plan, response/ recovery, exercise/study and crisis communication, etc. Risk management is a systematic method to identify, analyze, evaluate and treat emergency risks and risk assessment is composed of identifying, analyzing and evaluating emergency risks. Risk assesment is the first step for making BCP. In this study, risk assessment has been conducted for sewer laying project. Through assessing risks, 18 risks that may threaten the construction operation are identified and it is founded to be that high levels of risks which require treatment are 'collapse of excavation surface', 'breakage of ground infra-facilities', 'noise & dust dispersion' and 'rise of material costs'.

• Fire Science and Engineering
• /
• v.15 no.4
• /
• pp.1-9
• /
• 2001

The purpose of this study is to set up disaster prevention plan and risk assessment system considering combustion velocity at traditional housing zone. The combustion velocity analysis could contribute to build in disaster prevention technique through the potential risk analysis of the area, such analysis also able to set up comprehensive disaster prevention management system. Following results have achieved through the combustion velocity calculation. \circled1 The combustion velocity was calculated in order of the below winds, the above winds and the side winds. \circled2 It must be careful to set up disaster prevention plan in case of the below winds. \circled3 The combustion velocity was calculated at the density Bone where neighboring Distance and Length was small. \circled4 It proved that factors of each parameter not mostly effect to analyse the combustion velocity in limit of the 30 minutes after ignition. \circled5 At the density zone where Distance and Length is small the duration of transfer to neighboring house takes up to 4 minutes, it is required to set up of emergency response plan to minimize the fire dispersion.

• Journal of the Korean Institute of Gas
• /
• v.9 no.2 s.27
• /
• pp.43-49
• /
• 2005

Today toxic gas has various uses. If there is a release accident, the gas rapidly disperse into the atmosphere. The extent of damage due to toxic gas accident is very wide and fatal to human being. So, it is necessary for toxic gas facilities which have high risk to construct an emergency response system that prepare to toxic release and make immediate response to be possible at accident appearance. In this study accident scenario were selected and frequency analysis was executed using FTA technique. Dispersion effect of toxic gas release was analyzed using DNV company's PHAST(Ver. 6.2). Finally, an emergency response system was developed using results of quantitative risk analysis.

• Nuclear Engineering and Technology
• /
• v.11 no.2
• /
• pp.127-132
• /
• 1979

A model is considered in order to evaluate the potential risk from a nuclear facility directly combining the on-site meteorological data. The model is utilized to evaluate the environmental consequences from the routine releases during normal plant operation as well as following postulated accidental releases. The doses to individual and risks to the population-at-large are also analyzed in conjunction with design of rad-waste management and safety systems. It is observed that the conventional analysis, which is done in two separate unaffiliated phases of releases and atmospheric dispersion tends to result in unnecessary over-design of the systems because of high resultant doses calculated by multiplication of two extreme values.