• 한국ITS학회:학술대회논문집
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• 2008.11a
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• pp.301-308
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• 2008

• Journal of the Society of Naval Architects of Korea
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• v.54 no.1
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• pp.63-70
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• 2017

Release of hazardous and flammable gas is a significant contributor to risk. The ignition of flammable gas clouds can lead to explosion accidents in the offshore installations. A gas detector, which is one of active protect systems, brings the module into a safe state through emergency shut down processes and reduces the damage by eliminating the dangerous releases. It is critical to understand the gas release, the wind field, and the complex geometry of installations to determine gas detector placement. In this paper, the Gas detector Location Index (GLI) which is a novel index for optimal detector location determination to efficiently prevent explosion accident using probabilistic approach.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.5
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• pp.26-37
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• 2009

This paper suggests a sensor's placement method for detecting the dilemma zone problem when real-time driver's safety service is provided at signalized intersections by multiple pointed traffic sensors using USN environments. For detecting the dangerous situations from vehicles accelerating through yellow intervals, red-light running and stopping abruptly like as dilemma zone problem, VISSIM(microscopic, behavior-based multi-purpose traffic simulation program) is used to perform a real-time multiple detection situation by changing the input data like as various inflow-volume, design speed change, driver perception and response time. As a result, the optimal interval of traffic sensors is 20~27m, and the initialized sensor location from stop-line is different according to road design speed. Moreover, the pattern of detection about dilemma zone is also different according to inflow-volumes. This paper shows that the method is useful to evaluate the sensor's placement problem based on micro-simulation and the results can be used as the basic research for USN services.

• Journal of the Korean Society of Safety
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• v.32 no.5
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• pp.168-178
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• 2017

In order to prevent major and chemical accidents, some of the plants which would like to install and operate hazard chemicals handling facilities must submit Off-site Consequence Analysis due to recent arisen leak accidents since 2015. A lot of chemical industrials choose gas detectors as mitigation equipment to early detect gas vapor. The way of placement of gas detectors has two methods; Code-based Design(CBD) and Performance-based Design. The CBD has principles for gas detectors to be installed with consideration for the place that is expected to accumulate gas, and the leak locations according to legal standards and technical guidelines, and has a possibility to be unable to detect by these rules to locate gas detectors by vapor density information. The PBD has two methods; a Geographic Method and Scenario based Method. The Scenario-based Method has been suggested to make up for the Geographic Coverage Method. This Scenario-based Method draw the best optimum placement of gas detectors by considering leak locations, leak speed information, leak directions and etc. However, the domestic placement guidelines just refers to the CBD. Therefore, this study is to compare existing placement location of gas detectors by the domestic CBD with placement locations, coverages and the number of gas detectors in accordance with the Scenario-based Method. Also this study has measures for early detecting interest of Vapor Cloud and suitable placement of gas detectors to prevent chemical accidents. The Phast software was selected to simulate vapor cloud dispersion to predict the consequence. There are two cases; an accident hole size of leak(8 mm) from API which is the highst accident hole size less than 24.5 mm, and a normal leak hole size from KOSHA Guide (1.8 mm). Detect3D was also selected to locate gas detectors efficiently and compare CBD results and PBD results. Currently, domestic methods of gas detectors do not consider any risk, but just depend on domestic code methods which lead to placement of gas detectors not to make personnels recognize tolerable or intolerable risks. The results of the Scenario-based Method, however, analyze the leak estimated range by simulating leak dispersion, and then it is able to tell tolerable risks. Thus it is considered that individuals will be able to place gas detectors reasonably by making objectives and roles flexibly according to situations in a specific plant.

• Journal of the Korea Safety Management & Science
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• v.16 no.4
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• pp.379-389
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• 2014

Fire detectors are designed to minimize loss of life from a fire alarm system as an alarm to help evacuate more quickly until the completion of the evacuation alarm should be continued. the purpose of such alarms in order to achieve the characteristic fire heat release rate reaches a certain level, or when a certain time has elapsed, when the heat detector is to be alarms to answer. Requires a quick response, it is desirable to install the sensor as much as possible, but taking into account the cost of installation problems by engineering approach to minimize the quantity and rapidity of detection capability should be increased. In order to increase the rapidity of fire detectors in a room according to the height of the sensing period is to be maintained the optimum distance of the fire detector detects characteristics should be considered. Differential spot-type heat detectors installed domestic basis, depending on the type of sensor that can detect one sensor area is limited and less than 4m ceiling height regulations and simply double the number in excess of 4m and intended to be installed.

• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.799-806
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• 2012

In recent years, a new algorithm has been introduced to perform the regional overpower protection (ROP) detector layout optimization for $CANDU^{(R)}$ reactors. This algorithm is called DETPLASA. This algorithm has been shown to successfully come up with a detector layout which meets the target trip set point (TSP) value. Knowing that these ROP detectors are placed in a number of safety channels, one expects that there is an optimal placement of the candidate detectors into these channels. The objective of the present paper is to show that a slight improvement to the TSP value can be realized by optimizing the channelization of these ROP detectors. Depending on the size of the ROP system, based on numerical experiments performed in this study, the range of additional TSP improvement is from 0.16%FP (full power) to 0.56%FP.

• Journal of Radiation Industry
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• v.11 no.3
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• pp.157-165
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• 2017

In this paper, we calculate the light photons collection efficiency of large-volume plastic scintillation detector mainly used for radiation portal monitor (RPM). A Monte Carlo light photon transport code, DETECT2000, were used to quantitatively evaluate light collection efficiency of plastic scintillation detector. DETECT2000 calculated the placement of light collection efficiency based on the energy spectrum. We calculated the light collection efficiency relative to the position of the energy spectrum that proportional to the placement of the source. The $850{\times}285{\times}65mm^3$ size of polyvinyl toluene (PVT) scintillator was used for measurements. Through DETECT2000 simulation, the light collection efficiency of $5{\times}5$ arrays were calculated and verification was performed by comparing with experimentally measured. And then, the corrected MCNP simulation by applying the light collection efficiency in $21{\times}13$ arrays was compared and analyzed. Comparing the Monte Carlo simulation with measured results, it shows an average difference of 10.1% in $5{\times}5$ arrays. Particularly, about twice of the difference was found in the edge of first column, which coupled with PMT. In whole $5{\times}5$ array, the overall ratio was the same except for the first column. And then comparing the energy spectra of the $21{\times}13$ array with and without the light collection efficiency, it shows a difference of 6.69% in Compton edge area. The DETECT2000 based light collection efficiency simulation showed well agreement with the point source experiment. And comparing with measured energy spectra, we could compare the differences according to whether or not the light collection efficiency was applied. As a results, it is possible to increase the accuracy and reliability of Monte Carlo simulation results by pre-calculating the light collection efficiency according to the PVT geometry by using the DETECT2000.

• Fire Science and Engineering
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• v.24 no.1
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• pp.15-23
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• 2010

Placement method for fire detectors prescribed in current fire safety regulation is just about placing a prescribed number of detectors according to the areas. However, this regulation has no scientific basis and standards from foreign countries are just introduced and fire detectors are installed complying with them. There are two standards in designing fire protection systems; Prescriptive-Based Design that follows stipulated regulations like fire safety standards and Performance-Based Design based on engineering knowledge such as fire dynamics, structural dynamics, mechanics of materials, fluid mechanics, and thermo dynamics. Recently, Fire Protection System Construction Business Act was revised so that fire protection systems can be designed using Performance-Based Design method ('05. 8. 4), though the method has not activated until now. In addition, the enforcement decree defines the range for specific objects of fire protection to which Performance-Based Design is applied ('07, 1. 24). At the moment, by manufacturing simulator so that formulas can be introduced and calculated with software in order to install fire detector of automatic fire detection systems keeping optimized distance, comparing the results with the state of fire detector placed according to Performance-Based Design and analyzing them, this study was intended to settle Performance-Based Design method in the future.

• Imaging Science in Dentistry
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• v.48 no.3
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• pp.167-176
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• 2018

Purpose: In the age of X-ray computed tomography (CT) and digital volume tomography (DVT), with their outstanding post-processing capabilities, indications for planar radiography for the study of the dentition of ancient Egyptian mummies may easily be overlooked. In this article, the advantages and limitations of different approaches and projections are discussed for planar oral and maxillofacial radiography using portable digital X-ray equipment during archaeological excavations. Furthermore, recommendations are provided regarding projections and sample positioning in this context. Materials and Methods: A total of 55 specimens, including 19 skeletonized mandibles, 14 skeletonized skulls, 18 separate mummified heads, and 4 partially preserved mummies were imaged using portable digital X-ray equipment in the course of archaeological excavations led by the University of Basel in the Valley of the Kings between 2009 and 2012. Images were evaluated by 2 authors with regard to the visibility of diagnostically relevant dental structures using a 4-point grading system(Likert scale). Results: Overall, the visibility of diagnostically relevant dental structures was rated highest by both authors on X-ray images acquired using a dental detector. The tube-shift technique in the lateral projections of mandibular dentition achieved the second-best rating, and lateral projections achieved the third-best rating. Conclusion: Conventional planar digital X-ray imaging, due to its ubiquity, remains an excellent method-and often the only practicable one-for examining the skulls and teeth of ancient Egyptian mummies under field conditions. Radiographic images of excellent diagnostic quality can be obtained, if an appropriate methodology regarding the selected projections and sample placement is followed.

• Journal of Broadcast Engineering
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• v.25 no.6
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• pp.882-897
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• 2020

Recently, the use of immersive media contents representing Panorama and 360° video is increasing. Since the viewing angle is limited to generate the content through a general camera, image stitching is mainly used to combine images taken with multiple cameras into one image having a wide field of view. However, if the parallax between the cameras is large, parallax distortion may occur in the stitched image, which disturbs the user's content immersion, thus an image stitching overcoming parallax distortion is required. The existing Seam Optimization based image stitching method to overcome parallax distortion uses energy function or object segment information to reflect the location information of objects, but the initial seam generation location, background information, performance of the object detector, and placement of objects may limit application. Therefore, in this paper, we propose an image stitching method that can overcome the limitations of the existing method by adding a weight value set differently according to the type of object to the energy value using object detection based on deep learning.