• Journal of Korea Water Resources Association
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• v.46 no.5
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• pp.477-490
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• 2013

A rip-current warning index function, which is estimated from the likelihood of rip current quantified based on numerical simulations under various sea environments and is varied according to real-time buoy-observations, was studied to help protect against rip current accidents at Haeundae beach. For the quantification, the definition of likelihood of rip current, which proposed by Choi et al. (2011, 2012b), was employed and estimated based on Boussinesq modelling. The distribution of likelihood of rip current was evaluated by using various simulations according to scenarios established based on physical quantities(i.e., wave parameters) of buoy-observations. To index the likelihood of rip current, empirical functions were derived based on the distribution and adjusted to observational environments. In this study, the observations from June to September in 2011 at Haeundae beach were applied to the rip-current index functions, and its applications into the real events found based on CCTV images were presented and investigated. In addition, limitations and improvements of the rip-current index function were discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.199-208
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• 2017

Both cardiovascular diseases caused by decreased body composition and arterial compliance and falling induced by loss of muscle mass are frequent occurrences in the elderly. Therefore, elderly people are advised to perform elastic band resistance exercises to improve their body composition and arterial compliance. Thus, the purpose of this study was to examine the effects of 12 weeks of elastic band resistance training on the body composition, arterial compliance and falling index in elderly females (> 65 years). The elastic band resistance exercise program was administered 3 times per week for 60 minutes each time for 12 weeks. In addition, the exercise intensity was set to 11-14 on the Borg scale (6-20). Before and after the training period, the body composition (body weight (BW), muscle mass, % body fat, body mass index (BMI)), arterial compliance (ankle brachial index (ABI) and pulse wave velocity (PWV)) and risk of falling index were determined. (After the program?), the BW (p=.003), BMI (p=.002), PWV (p=.017) and risk of falling (p=.037) in the exercise group were significantly reduced, whereas the BW (p=.009) and BMI (p=.009) in the control group were significantly increased. In conclusion, the body weight, BMI and arterial compliance of elderly females were positively changed by the elastic band resistance training. Thus, the elastic band resistance exercise may be useful for elderly people to prevent metabolic syndrome and cardiovascular diseases and to reduce their risk of falling.

• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.6-15
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• 2017

Process safety management(PSM) system was implemented in Korea since 1996. It helps reduce and prevent the occurrence of chemical accidents. There has been no review on the feasibility of the threshold quantities of the existing 21 species and the newly added toxic substances such as hydrogen bromide in the PSM system. The threshold quantities of the target toxic substances(25 species) of PSM were compared with domestic and foreign PSM systems similar to those of Korea. Also, we proposed the toxic harmfulness and hazard equation consisted of inhalation toxicity, NFPA index and others. According to this equation, high risk, medium risk and low risk are classified and reflected in the adjustment of threshold quantities. From the above research, It is expected to help to reduce confusion and burden of the workplaces due to the difference from other PSM system and improve in the threshold quantities.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.192-202
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• 2021

In the past, various studies have been conducted on safety facility installation standards and road safety indices. But there are limitations in applying them to the field, such as using many survey items and variables that are difficult to use. Therefore, this study attempted to develop road safety judgment indicators considering the applicability of the research results and to prepare criteria for installing safety facilities. As part of the study, data of related systems were reviewed, and the use of variables already in use was figured out. Furthermore, the road safety judgment indicators reflecting traffic, road, and accident factors were developed through correlation and factor analysis. Later, the criteria score for determining the installation of safety facilities was derived through cluster analysis. The analyses suggested, that the installation judgment criterion score at the intersection was lower than that of the single road(crosswalk), and the road risk at the intersection was higher.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.27-35
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• 2024

Fuel gases such as methane and propane are used in explosion hazardous area of domestic plants and can form non-uniform mixtures with the influence of process conditions due to leakage. The fire-explosion risk assessment using literature data measured under uniform mixtures, damage prediction can be obtained the different results from actual explosion accidents by gas leaks. An explosion characteristics such as explosion pressure and flame velocity of non-uniform gas mixtures with concentration change similar to that of facility leak were examined. The experiments were conducted in a closed 0.82 m long stainless steel duct with observation recorded by color high speed camera and piezo pressure sensor. Also we proposed the quantification method of non-uniform mixtures from a regression analysis model on the change of concentration difference with time in explosion duct. For the non-uniform condition of this study, the area of flame surface enlarged with increasing the concentration non-uniform in the flame propagation of methane and was similar to the wrinkled flame structure existing in a turbulent flame. The time to peak pressure of methane decreased as the non-uniform increased and the explosion pressure increased with increasing the non-uniform. The ranges of K_G (Deflagration index) of methane with the concentration non-uniform were 1.30 to 1.58 [MPa·m/s] and the increase rate of K_G was 17.7% in methane with changing from uniform to non-uniform.

• Journal of Navigation and Port Research
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• v.43 no.4
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• pp.250-255
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• 2019

The objective of this study was to analyze the risk of collision accidents to the VTSOs (Vessel Traffic Service Operators) as small ferries and fishing boats are expanded for monitoring targets. The VTSOs was surveyed, the scale of the small vessels defined and the course of general cargo vessels and small vessels along the Busan VTS area investigated for three days. From calculating the risk with CoRI, patterns of increased or decreased risk due to course deviation were similar, and there was no significant difference between the maximum values and the minimum values. In addition, most VTSOs responded that the minimum time required was approximately three minutes to safely instruct in encounter situation, however, the collision risk with a small vessel is very rapidly changing within the three minutes, which is likely to increase the workload and decrease the concentration of the VTSOs. The objective of this study was to investigate the effect on VTSOs with respect to the expansion of small vessels as collision risk, it is expected that it will contribute to the establishment of a suitable scale for the target vessels for VTS through the analysis of each index of the CoRI model and various case studies.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.3
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• pp.273-279
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• 2007

Probabilistic Risk Assessment considering statistically random variables is performed for the preliminary design of an Arch Bridge. Component reliabilities of girders have been evaluated using the response surfaces of the design variables at the selected critical sections based on the maximum shear and negative moment locations. Response Surface Method (RSM) is successfully applied for reliability analyses lot this relatively small probability of failure of the complex structure, which is hard to be calculated by Monte-Carlo Simulations or by First Order Second Moment method that can not easily calculate the derivative terms in implicit limit state functions. For the analysis of system reliability, parallel resistance system composed of girders is modeled as a parallel series connection system. The upper and lower probabilities of failure for the structural system have been evaluated and compared with the suggested prediction method for the combination of failure modes. The suggested prediction method for the combination of failure modes reveals the unexpected combinations of element failures in significantly reduced time and efforts, compared with the previous permutation method or conventional system reliability analysis method.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.367-373
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• 2016

Many of plastic powders handled in industry are combustible and have the hazard of dust fire and explosion accidents. However poor information about the safe handling has been presented in the production works. The aim of this research is investigated experimentally on explosive characteristics of various plastic powders used in industry and to provide additional data with safety informations. The explosibility parameters investigated using standard dust explosibility test equipment of Siwek 20-L explosion chamber. As the results, the dust explosion index ($K_{st}$) of ABS ($209.8{\mu}m$), PE ($81.8{\mu}m$), PBT ($21.3{\mu}m$), MBS ($26.7{\mu}m$) and PMMA ($14.3{\mu}m$) are 62.4, 59.4, 70.3, 303 and 203.6[$bar{\cdot}m/s$], respectively. And flame propagation velocity during plastic dust explosions for prediction of explosive damage was estimated using a flame propagation model based on the time to peak pressure and flame arrival time in dust explosion pressure assuming the constant burning velocity.

• Journal of Korean Society of Transportation
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• v.24 no.1 s.87
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• pp.121-131
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• 2006

Considering characteristics of drivers and vehicles with proper and reliable ways in highway design Procedures can ensure high level of highway safety. However, it is almost impossible to take into account all factors of drivers and vehicles influencing on the highway safety because of their uncertain and random nature. To detour the dead-end, the nature are usually assumed as simple homogeneous and deterministic one. Although the restricted assumption makes the system simple, it can produce serious problems due to lack of considering variability in the system. This paper develops a reliability-based method for determining stopping sight distance(SSD) and intersection sight distance (ISD), which are crucial elements in highway alignment design. In the study, Hasofer-Lind method is adopted. which is a well-known first-order second moment reliability method (AFOSM) The results in this study show that if mean, variance, and distribution of a particular driver-vehicle parameter are known, more reliable sight distances can be applied in highway design procedures because we can reflect uncertainties and randomness. Thus, the Probabilistic method could be adopted in designing the sight distance(s) with the desired reliability level.

• Fire Science and Engineering
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• v.14 no.4
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• pp.7-16
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• 2000

In the study, three criteria(toxicity, fire & explosion, environment) and damage prediction method for each case was set up, and all these criteria were applied to the subject substance that was selected as hazardous level by integrating all criteria through Algorithm. Particularly, the environment criterion is a comprehensive concept, environment index modeling by combining USCG(United State Coast Guard) & MSDS(Material Safety Data Sheet) environment criteria classifications and the environment part of MFPA's health hazardousnes(Nh). And for damage prediction method of each criterion were adopted and they were applied to hazardous chemical substances in use or stored by chemical substance related enterprises located in each region that made possible to set up total hazard level of used substances(inflammability, poisonousness and counteraction on a unit substance, and hazard level & display modeling on environment) & damage prediction in case of accident & solidity setup(CPQRA: Chemical Process Quantitative Risk Assessment, IAEA: International Atomic Energy Agency, VZ eq: Vulnerable Zone) risk counter. Thus it is deemed that it can be applied to toxic substance leakage that can happen during any chemical processing & storage, application as a tool for prior safety evaluation through potential dangerousness computation of fire & explosion.