• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.60-75
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• 2019

Nowadays, interest in safety of pedestrians who are relatively weak when compared with vehicles increases. Also, concern for pedestrian accidents on crosswalks increases. For these reasons, scrambled crosswalks which are considered to contribute pedestrian safety by reducing conflicts between vehicles and pedestrians are actively discussed and there are also a few intersections where they are actually installed. However, scrambled crosswalks must include all-red phase for all vehicle traffic flows, which inevitably leads to increase of lost time per cycle. Therefore, evaluation in terms of efficiency should be done before installation of scrambled crosswalks. This research suggests installation criteria for scrambled crosswalks so that it is possible to judge whether installation of scrambled crosswalks is appropriate only by surveying vehicle traffic volume and pedestrian traffic volume. This research derives optimum cycle length from signal optimization models which considers both vehicle traffic volume and pedestrian traffic volume. From this optimum cycle length, this research compares total delay time before and after installation of scrambled crosswalks. From an analysis, two research results are derived. Firstly, there is critical traffic volume above which installation of scrambled crosswalks can not efficient. Secondly, appropriate areas for installation of scrambled crosswalks are different by each signal intersection or by each signal system and those difference vary. From these results, this research suggests installation criteria for scrambled crosswalks which consists of two steps. The delay time of the pedestrians may be increased after the diagonal crosswalk is installed, but it may be desirable to install in consideration of the appropriate traffic level to ensure safety.

• Journal of Aerospace System Engineering
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• v.7 no.2
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• pp.29-34
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• 2013

Safety requirements for aircraft and system functions include minimum performance constraints for both availability and integrity of the function. These safety requirements should be determined by conducting a safety assessment. The depths and contents of aircraft system safety assessment vary depending on factors such as the complexity of the system, how critical the system is to flight safety, what volume of experience is available on the type of system and the novelty and complexity of the technologies being used. Requirements that are defined to prevent failure conditions or to provide safety related functions should be uniquely identified and traceable through the levels of development. This will ensure visibility of the safety requirements at the software and electronic hardware design level. This paper has prepared to study on promoting the efficiency of establishing hierarchical safety requirements from aircraft level function to item level through system safety processes.

• Progress in Medical Physics
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• v.21 no.4
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• pp.354-359
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• 2010

The purpose of this study is to verify the dosimetric effect on real PTV (planning target volume) coverage and safety of OARs (organs at risk) at various image fusion protocol-based radiosurgery plan for pituitary adenomas. Real PTV coverage and its variation was acquired and maximum dose and the volume absorbing above threshold dose were also measured for verifying the safety of optic pathway and brainstem. The protocol that can reduce superior-inferior uncertainty by using both axial and coronal MR (magnetic resonance) image sets shows relatively lower values than that of case using only axial image sets. As a result, the image fusion protocol with both axial and coronal image sets can be beneficial to generate OAR-weighted radiosurgery plan.

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.54-61
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• 2015

A series of CFD calculation has been conducted to investigate the effect of facility confinement on explosion power for process plant facility. The level of confinement of a facility was simplified with VBR(volume blockage ratio) and averaged size of obstacles. FLACS which is 3D CFD code of gas dispersion and the explosion was used for simulating the explosion phenomena in the idealized domain with different confinement level. The CFD results showed a tendency that the overpressure increases with increasing VBR and number of obstacles. The effect of VBR on the overpressure was relatively small for the case of number of obstacle less than 25. The results of this study can be used to provide a safety guideline considering the facility confinement in case of leakage accident of flammable gas and vapor in process plants.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.381-388
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• 2018

This study proposes marine traffic volume estimation method considering ship speed, a factor excluded from the existing method. Ten days of GICOMS marine traffic data from Pyeongtaek and Dangjin ports was applied to this study. As a result, converted traffic volume with the proposed estimation method showed an increase of 4.41 (${\pm}0.99$) times or decrease of 0.59 (${\pm}0.04$) at most, compared with the existing estimation method. Average marine traffic congestion for each time applying the proposed estimation method showed an increase of 1.43 (${\pm}0.10$) compared with the existing estimation method. The maximum marine traffic congestion for each time was 1.62 (${\pm}0.34$) times higher compared with the existing estimation method. Marine traffic peak time, defined as the highest point of marine traffic congestion, was evaluated to be different from that of the existing method because of distribution of vessel speed. In conclusion, considering ship speed is necessary when estimating marine traffic volume to produce a practical estimate of marine traffic capacity.

• Proceedings of the Korean Society of Toxicology Conference
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• 2005.05a
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• pp.136-136
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• 2005

• Journal of Ocean Engineering and Technology
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• v.32 no.4
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• pp.272-278
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• 2018

Recently, the use of hazardous chemicals has been continuously increasing. Therefore, the international trade volume is growing and chemical accidents have increased. Nowadays, the safety awareness of the public has increased. As a result, the management and supervision of hazardous chemicals have been strengthened. However, the port policy of Korea has focused on increasing the volume of cargo through facility development. Thus, the port management of hazardous chemicals has been relatively neglected. For national economic growth and society, the port management of hazardous chemicals should be considered to efficiently ensure safety and economic growth. Therefore, this study assumed scenarios where hazardous materials were moved in a dangerous container, not only on appropriate wharfs but also in ports that were close to a big city. The BTX substances were selected among the toxic chemicals with large import and export volumes, and the risk distance and damage effects were predicted using various risk assessment programs. It is expected that this could be used to improve a port safety management system and could be utilized to determine the safety distance in case of an accident.

• Nuclear Engineering and Technology
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• v.18 no.3
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• pp.175-182
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• 1986

The KNUI (Korea Nuclear Unit 1) loss of offsite power transient as a design-base accident has been simulated using the RELAP5/MOD1/NSC computer code. The analysis is carried out using the best-estimate methodology, but the sequence and its assumptions are based on the evaluation methodology th at emphasizes conservatism. Important thermal-hydraulic parameters such as average temperature, steam generator level and pressurizer water volume are compared with the results in the KNU1 Final Safety Analysis Report (FSAR). The present analysis gives much lower RCS average temperature and pressurizer water volume, and much higher S/G water volume at the turnaround point, which may be considered to be additional improved safety margins. This is expected since the present analysis deals with the best-estimate thermal-hydraulic models as well as the initial conditions on a best-estimate basis. These additional safety margins may contribute to further validate the safety of the KNU1 in this type of accidents(Decrease in Heat Removal by the Secondary System).

• The KSFM Journal of Fluid Machinery
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• v.19 no.5
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• pp.50-60
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• 2016

A design methodology of the modeled test facility to conserve an injection performance of a passive safety injection system is proposed. This safety injection system is composed of a core makeup tank and a safety injection tank. Individual tanks are connected with pressure balance line on the top side and injection line on the bottom side. It is important to conserve the scaled initial injection flow rate and total injection time since this system can be operated by small gravity head without any active pumps. Differential pressure distribution of the injection line induced by the gravity head is determined by the vertical length and elevation of each tank. However, the total injection time is adjustable by the flow resistance coefficient of the injection line. The scaling methodology for the tank and flow resistance coefficient is suggested. A key point of this test facility design is a scaling analysis for the flow resistance coefficient. The scaling analysis proposed on this paper is based on the volume scaling law with the same vertical length to the prototype and can be extended to a model with a reduced vertical length. A set of passive injection test were performed for the tanks with the same volume and the different length. The test results on the initial flow rate and total injection time showed the almost same injection characteristics and they were in good agreement with the design values.

• Proceedings of the KOR-KST Conference
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• 1997.12a
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• pp.33-69
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• 1997

This study was conducted to develop a methodology to predict utility pole accident rates and to evaluate cost-effectiveness for safety improvement for utility pole accidents. The utility pole accident rate prediction model was based on the encroachment rate approach introduced in the Transportation Research Board Special Report 214. The utility pole accident rate on a section of highway depends on the roadside encroachment rate and the lateral extent of encroachment. The encroachment rate is influenced by the horizontal and vertical alignment of the highway as well as traffic volume and mean speed. The lateral extent of encroachment is affected by the horizontal and vertical alignment, the mean speed and the roadside slope. An analytical method to generate the probability distribution function for the lateral extent of encroachment was developed for six kinds of encroachment types by the horizontal alignment and encroachment direction. The encroachment rate was calibrated with the information on highway and roadside conditions and the utility pole accident records collected on the sections of 55mph speed limit of the State Trunk Highway 12 in Wisconsin. The encroachment rate on a tangent segment was calibrated as a function of traffic volume with the actual average utility pole accident rates by traffic volume strategies. The adjustment factors for horizontal and vertical alignment were then derived by comparing the actual average utility pole accident rates to the estimations from the model calibrated for tangent and level sections. A computerized benefit-cost analysis procedure was then developed as a means of evaluating alternative countermeasures. The program calculates the benefit-cost ratio and the percent of reduction of utility pole accidents resulting from the implementation of a safety improvement. This program can be used to develop safety improvement: alternatives for utility pole accidents when a predetermined performance level is specified.