• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.135-140
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• 2014

Pressure vessels are used in various industrial fields. If a defect occurs on the inner or outer surface of a pressure vessel, it may cause a massive accident. A defect on the outer surface can be detected by visual inspection. However, a defect on the inner surface is generally impossible to detect with visual inspection. Nondestructive testing can be used to detect this type of defect. Laser speckle shearing interferometry is one nondestructive testing method that can optically detect a defect; its advantages include noncontact, full field, and real time inspection. This study evaluated the detectable size for an internal defect of a pressure vessel. The material of the pressure vessel was ASTM A53 Gr.B. The internal defect was detected when the pressure vessel was loaded by internal pressure controlled by a pneumatic system. The internal pressure was controlled from 0.2 MPa to 0.6 MPa in increments of 0.2 MPa. The results confirmed that an internal defect with a 25 % defect depth could be detected even at 0.2 MPa pressure variation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.731-736
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• 2021

Oil fences effectively prevent the spread of oil spilled in the sea, thereby reducing the damage to the marine environment. However, the fence is damaged by oil and structures at the accident site and is discarded. When incinerated disposal method for discarded fences, fine dust, and harmful materials are generated. Moreover, as a part of the damaged fence is dumped into the sea, it may cause secondary environmental pollution, such as microplastics. Therefore, in this study, durability was measured using the most common solid foam type oil fences. As a result, the reduction rate of after five days of contact was 13 % in seawater and 3 % in oil, affected by temperature changes. Thus, the durability of the fence should be improved because it is exposed to seawater and oil and affected by wind, light, and waves depending on the weather conditions. Therefore, we suggest a method to improve the oil fence inspection to strengthen the durability of the fence's fabric part.

• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.535-546
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• 2010

Recently, the probability of collision accident between vehicles or vessels and infrastructures are increasing at alarming rate. Particularly, collision impact load can be detrimental to sub-structures such as piers and columns. The damaged pier from an impact load of a vehicle or a vessel can lead to member damages, which make the member more vulnerable to impact load due to other accidents which. In extreme case, may cause structural collapse. Therefore, in this study, the vehicle impact load on concrete compression member was considered to assess the quantitative design resistance capacity to improve, the existing design method and to setup the new damage assessment method. The case study was carried out using the LS-DYNA, an explicit finite element analysis program. The parameters for the case study were cross-section variation of pier, impact load angle, permanent axial load and axial load ratio, concrete strength, longitudinal and lateral rebar ratios, and slenderness ratio. Using the analysis results, the performance based resistance capacity evaluation method for impact load using satisfaction curve was developed using Bayesian probabilistic method, which can be applied to reinforced concrete column design for impact loads.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.353-362
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• 2015

Platform screen door (PSD) installed at underground subway station has reduced the safety accident, but it may cause poor air ventilation condition due to the isolated exhaust duct in the subway tunnel area. In this study, the additional ventilation system was suggested, which can be installed at a void space (i.e., storage room under stairs) of platform in order to improve efficiency of air ventilation rate. Exhausted air from platform was directed to underneath of platform and joined with existing ventilation duct of train exhaust system (TES). One subway station in Seoul city was selected to predict the effectiveness of the suggested lower exhaust system by using the computational fluid dynamics (CFD) analysis. The predicted mean age of air was decreased by 16.5% which proves the improvement of air ventilation efficiency when the suggested lower exhaust system was applied.

• Journal of agricultural medicine and community health
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• v.30 no.3
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• pp.255-262
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• 2005

Purpose: In Ulleung island, emergency medical transport by helicopter is very important. So, we analysized our experience with emergency medical transport by helicopter for 4 years and we were compared our data with other data for 1997-2001. Therefore we need to research public health development direction. Method: We analysized patient's medical record for 4 years. Result: During 4 years, 104 transports were done and 130 patients were trasported to tertiary hospital center, there was more increased than that from 1997 to 2001. Helicopters from Pohang coast guard, Donghae coast guard, Navy, and 119 rescue etc. were used, but 119 rescue transport was decreased more and more. The 60's patients was most, 22.3% and teenager's and 80's patients was lowest. The male was 65% but the female was increased more and more annually. In addition, the older patients was the more portion of female patient. The transport was concentrated in daytime. The traumatic patient was much in winter period. The cerebrovascular accident was 1st cause of patient and fracture was many also. Conclusioon: Except Fire service's helicopter, the other helicopter was not apt to emergency medical tansport. But Fire service's helicopter was not used commonly because Fire service's helicopter was in Daegu, so distant and time consumed. As a result, emergency medical transport helicopter is needed in east coast like Fire service's helicopter. In addition, trauma prevention education and public health education for hypertension and diabetes will be essential and public health system in Ulleung island will be prepared for aging society.

• Korean Security Journal
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• no.51
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• pp.11-35
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• 2017

The third industrial revolution, characterized by factory automation and informatization, are moving toward the fourth industrial revolution which is the era of superintelligence and supernetworking through rapid technology innovation. The most important resources in the fourth industrial revolution are information or data since the most of industrial and economic activities will be affected by information in the fourth industrial revolution. Therefore we can expect that more information will be utilized, shared and transfered through the networks or systems in real time than before so the significance of information management and security will also increase. As the importance of information resource management and security which is the core of the fourth industrial revolution increases, the threats on information security are also growing so security incidents such as data breeches and accidents take place more often. Various and thorough solutions are highly needed to protect information resources from security risks because information accidents or breaches seriously damage brand image and cause huge financial damage to organization. The purpose of this study is to research general trends on data breaches and accident that can be serious threat of information security. Also, we will provide resonable solutions to protect data from nine attack patterns or other risk factors after figuring out each characteristic of nin attack patterns in data breaches and accidents.

• Journal of Digital Convergence
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• v.15 no.11
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• pp.245-250
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• 2017

Flash floods is defined as the flooding of intense rainfall over a relatively small area that flows through river and valley rapidly in short time with no advance warning. So that it can cause damage property and casuality. This study is to establish the flash-flood warning system using 38 accident data, reported from the National Disaster Information Center and Land Surface Model(TOPLATS) between 2009 and 2012. Three variables were used in the Land Surface Model: precipitation, soil moisture, and surface runoff. The three variables of 6 hours preceding flash flood were reduced to 3 factors through factor analysis. Decision tree, random forest, Naive Bayes, Support Vector Machine, and logistic regression model are considered as big data methods. The prediction performance was evaluated by comparison of Accuracy, Kappa, TP Rate, FP Rate and F-Measure. The best method was suggested based on reproducibility evaluation at the each points of flash flood occurrence and predicted count versus actual count using 4 years data.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.2
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• pp.153-158
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• 2016

Purpose: This study was aimed to investigate effects of breath alcohol concentration (BrAC) increase on visual field and readable visual field. Methods: 23 males in 20s (average age $21.17{\pm}2.19years$, body mass index (BMI) $22.09{\pm}2.16$) were selected and administered the amount of alcohol to reach 0.05% and 0.08% BrAC calculated by BAC (blood alcohol concentration) Dosing Software program. Then, visual field and readable visual field test with Vision Disk were conducted. Results: Visual field are measured as $74.41{\pm}15.97^{\circ}$, $64.98{\pm}17.93^{\circ}$, and $58.33{\pm}19.01^{\circ}$ (p=0.000) and readable visual field as $21.93{\pm}12.71^{\circ}$, $17.41{\pm}11.36^{\circ}$, $14.26{\pm}9.93^{\circ}$ (p=0.006) in 0.00%, 0.05% and 0.08% BrAC respectively. As breath alcohol concentration increased, both visual field and readable visual field decreased. Conclusions: BrAC increase with drinking could be the cause of safety accident by decreasing visual field and readable visual field, it is necessary to raise awareness.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.3
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• pp.679-691
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• 2016

As vehicle started to contain many different communication devices, collecting external information became possible in IoT environment. In such environment, remotely controling vehicle is possible when vehicle information is obtained by looking in to vehicle network through smart device. However, android based smart device applications are vulnerable to malicious modulation and redistribution. Modulated android application can lead to vehicle information disclosure that could bring about vehicle control accident which becomes threat to drivers. furthermore, since vehicles today does not contain security methods to protect it, they are very vulnerable to security threats which can cause serious damage to users and properties. In this paper, many different vehicle management android applications that are sold in Google Play has been analyzed. With this information, possible threats that could happen in vehicle management applications are being analysed to prove the risks. the experiment is done on actual vehicle to prove the risks. Also, access control method to protect the vehicle against malicious actions that could happen through external network in IoT environment is suggested in the paper.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.1
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• pp.99-107
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• 2016

Korea has been known as volcanic disaster free area. However, recent surveying result shows that Baekdu mountain located in northernmost in the Korean peninsula is not a dormant volcano anymore. When Baekdu mountain is erupting, various damages due to the volcanic ash are expected in South Korea area. Especially, volcanic ash in the air may cause big aviation accident because it can hurt engine or gauges in the airplane. Therefore, it is a crucial issue to interrupt airplane navigation, whose route is overlapped with volcanic ash, after predicting three dimensional dispersion of volcanic ash. In this paper, we deals with 3D visualization techniques for volcanic ash dispersion prediction results. First, we introduce the data acquisition of the volcanic ash dispersion prediction. Dispersion prediction data is obtained from Fall3D model, which is volcanic ash dispersion simulation program. Next, three 3D visualization techniques for volcanic ash dispersion prediction are proposed. Firstly proposed technique is so called 'Cube in the Air', which locates the semitransparent cubes having different color depends on its particle concentration. Second technique is a 'Cube in the Cube' which divide the cube in proportion to particle concentration and locates the small cubes. Last technique is 'Semitransparent Volcanic Ash Plane', which laminates the layer, whose grids present the particle concentration, and apply the semitransparent effect. Based on the proposed techniques, the user could 3D visualize the volcanic ash dispersion prediction results upon his own purposes.