• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.2
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• pp.36-49
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• 2016

A subway system is one of the major transportation modes at a metropolitan area. When it meets the other lines, the metro station, so-called transferring station, is usually threatened by severe pedestrian congestion and safety issue of transit users including the transportation vulnerable. Although transportation planners forecast travel demand at the beginning, it is not easy to predict pedestrian flows precisely for a long term if land use plans have dramatically changed. Due to expensive costs, structural extension of metro stations is limited. Therefore, it requires efficient and technical improvements as meeting the demand of pedestrian and physical characteristics. In this study, the core mechanism of pedestrian movement-based simulation model was introduced and evacuation scenarios were analyzed with the developed model. As a result, the multiple optimal routes for unexpected events at the solid space of the multiple stories are easily searched through the simulator and in the case of Sadang Station, travel time can be reduced by 60% when the evacuation information and intuitive design are provided.

• Korean Journal of Remote Sensing
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• v.25 no.5
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• pp.435-444
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• 2009

In the case of oil spill accident at sea, information concerning the movement of spilled oil is important in making response strategies. Aircrafts and the satellites have been utilized for monitoring of spilled oil. In these days, numerical models are using to predict the movement of the spilled oil. In the future a coupling method of modeling and remote sensing data should be needed to predict more correctly the spilled oil. The purpose of this paper is to present an application of satellite image data to an oil spill prediction model as an initial condition. Environmental Fluid Dynamics Computer Code (EFDC) was used to predict the movement of the oil spilled from Hebei Spirit incident occurred in Taean coastal area on December 7,2007. In order to make the model initial condition and to compare the model results, two satellite images, KOMPSAT-2 MSC and ENVISAT ASAR obtained on December 8 and 11, were used during the period of the oil spill incident. The model results showed an improvement for the prediction of the spilled oil by using the initial condition deduced from satellite image data than the initial condition specified at the oil spill incident site in the respects of the distributed spilled area.

• Journal of Preventive Medicine and Public Health
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• v.52 no.6
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• pp.405-415
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• 2019

Objectives: The aim of this study was to evaluate the associations of frailty with perceived neighborhood walkability and environmental pollution among community-dwelling older adults in rural areas. Methods: The participants were 808 community-dwelling men and women aged 65 years and older in 2 rural towns. Comprehensive information, including demographics, socioeconomic status, grip strength, polypharmacy, perceived neighborhood environment (specifically, walkability and environmental pollution), and frailty, was collected from participants using face-to-face interviews conducted between June and August 2018. Perceived neighborhood walkability was measured using 20 items that were selected and revised from the Neighborhood Environment Walkability Scale, the Neighborhood Walkability Checklist from the National Heart Foundation of Australia, and the Physical Activity Neighborhood Environment Survey. The Kaigo-Yobo Checklist was used to assess participants' frailty. Results: The overall prevalence of frailty in this community-dwelling population was 35.5%. Sex, age, cohabitation status, educational attainment, employment status, grip strength, and polypharmacy were significantly associated with frailty. In the logistic regression analysis, frailty was associated with low perceived neighborhood walkability (adjusted odds ratio [aOR], 0.881; 95% confidence interval [CI], 0.833 to 0.932; p<0.001) and severe perceived neighborhood environmental pollution (aOR, 1.052; 95% CI, 1.017 to 1.087; p=0.003) after adjusting for sex, age, cohabitation status, educational attainment, employment status, monthly income, grip strength, and polypharmacy. Conclusions: More studies are warranted to establish causal relationships between walkability and environmental pollution and frailty.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.265-277
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• 2019

Changes in the amount, intensity, frequency, and type of precipitation, in conjunction with global warming and climate change, critically impact groundwater recharge and associated groundwater level fluctuations. Monthly gravity levels by the Gravity Recovery and Climate Experiment (GRACE) are acquired to monitor total water storage changes at regional and global scales. However, there are inherent difficulties in quantitatively relating the GRACE observations to groundwater level data due to the difficulties in spatially representing groundwater levels. Here three local interpolation methods (kriging, inverse distance weighted, and natural neighbor) were implemented to estimate the areal distribution of groundwater recharge changes in South Korea during the 2002-2016 period. The interpolated monthly groundwater recharge changes are compared with the GRACE-derived groundwater storage changes. There is a weak decrease in the groundwater recharge changes over time in both the GRACE observations and groundwater measurements, with the rate of groundwater recharge change exhibiting mean and median values of -0.01 and -0.02 cm/month, respectively.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.315-327
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• 2019

Back analysis has been used to evaluate the factor of safety and circular failure plane at the landfill failure site. However, the estimated circular failure plane by back analysis is quite different from what is observed in the field. Thus, this study was conducted to estimate an actual shear failure plane inside the ground which gives a more accurate failure plane. Cone penetration test (CPT), boring test, soft X-ray image scan, density logging, and ultrasonic logging were conducted at the field and laboratory. The result of CPT showed significantly lower cone resistance, pore pressure, and undrained shear strength at a particular part. This part is a possible shear failure plane inside the ground. To validate, the soft X-ray scan images were analyzed and found the disturbed (inclined) bedding plane induced by shear activity at the estimated shear failure plane. Density and ultrasonic logging tests also found a similar result. Thus, the method in this study is possible to estimate the shear failure plane inside the ground.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.9
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• pp.217-224
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• 2019

Recently, sensor networks are built and used on many kinds of fields such as home, traffic, medical treatment and power grid. Sensing data manipulation on these fields could be a serious threat on property and safety. Thus, a proper way to block sensing data manipulation is necessary. In this paper, we propose IoT(Internet of Things) sensing data validation mechanism based on data obfuscation and variance analysis to remove manipulated sensing data effectively. IoT sensor device modulates sensing data with obfuscation function and sends it to a user. The user demodulates received data to use it. Fake data which are not modulated with proper obfuscation function show different variance aspect with valid data. Our proposed mechanism thus can detect fake data by analyzing data variance. Finally, we measured data validation time for performance analysis. As a result, block rate for false data was improved by up to 1.45 times compared with the existing technique and false alarm rate was 0.1~2.0%. In addition, the validation time on the low-power, low-performance IoT sensor device was measured. Compared to the RSA encryption method, which increased to 2.5969 seconds according to the increase of the data amount, the proposed method showed high validation efficiency as 0.0003 seconds.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.5
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• pp.1-9
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• 2021

In Korea, various information related to COVID-19 has been provided to the public through an EAM (Emergency Alert Message) service using CBS (Cell Broadcast Service) technology to respond to COVID-19. In particular, local governments have been actively using the EAM service as a major means of responding to COVID-19. However, since excessive use of EAM service has caused the inconvenience of the people rather than the positive effects, the authority to be able to send EAMs has be limited. In this paper, with the purpose of providing primary data for establishing a plan to properly operate EAMs, we compare and analyze the number of EAMs issued and the incidence rate of COVID-19 cases during the period from 2020 to the present. In addition, the monthly EAM usage and incidence rate of COVID-19 cases are compared in detail and correlation analysis is performed for local governments that have issued many EAMs. We expect that the analysis results of this paper will be used as primary data in establishing strategies for EAM service to counteract the prolonged COVID-19.

• Journal of Convergence for Information Technology
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• v.11 no.11
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• pp.172-177
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• 2021

As part of the digital era, a digital twin that simulates the weak part of a product by performing a stress test that reduces the lifespan of some expensive equipment that cannot be done in reality by accurately moving the real world to virtual reality is being actively used in the manufacturing industry. Due to the development of IoT, the digital twin, which accurately collects data collected from the real world and makes it the same in the virtual space, is mutually beneficial through accurate prediction of urban life problems such as traffic, disaster, housing, quarantine, energy, environment, and aging. Based on its action, it is positioned as a necessary tool for smart city construction. Although digital twin is widely applied to the manufacturing field, this study proposes a smart city model suitable for the 4th industrial revolution era by using it to smart cities and increasing citizens' safety, welfare, and convenience through the proposed model. In addition, when a digital twin is applied to a smart city, it is expected that more accurate prediction and analysis will be possible by real-time synchronization between the real and virtual by maintaining realism and immediacy through real-time interaction.

• Journal of Convergence for Information Technology
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• v.11 no.11
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• pp.204-209
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• 2021

This study is a data analysis study to identify the factors influencing the prevalence and risk factors for falls of older adults with dementia in Korea. Using the data of the 7th Aging Research Panel in 2018, 119 people were enrolled. We used response data on the dementia-related factors that is the duration of dementia and whether or not activity of daily living was restricted due to dementia. For comorbid diseases, data on hypertension, diabetes, and obesity were used. For statistical analysis of the collected data, logistic regression analysis was performed using SPSS statistics 22.0. Dementia-related factors and comorbidities of the analyzed subjects had a significant effect on the falling index. In particular, it was found that the influence was greatest in the order of obesity, diabetes, hypertension, daily life restrictions due to dementia, and the duration of dementia. This study is meant to identify factors that should be prioritized in the composition of a fall prevention program for the elderly with dementia. Based on the findings of this study, strategies for preventing falls due to the duration of dementia and limiting daily life, intensive management of high-risk groups for falls due to comorbid diseases, and training in the use of safety aids such as walking aids will be required in the care of the elderly with dementia,

• Journal of Plant Biotechnology
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• v.47 no.4
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• pp.261-272
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• 2020

Approvals for cultivation and import of genetically modified (GM) crops have dramatically increased around the world. Comparative compositional studies are an important aspect of safety assessments of products from GM crops and are based on substantial equivalence. Compositional analyses focus on determining similarities and differences between the compositions of the GM crops and their conventional counterparts, and thereby assessing the compositional equivalence of GM crops and their conventional comparators. The analytes, such as major constituents, key nutrients, and antinutrients, are generally determined on a crop-specific basis according to the OECD consensus document. The use of standard methods throughout the processes, such as selection of comparators, field trials, analytical methods, and statistical data analysis, is crucial. In this study, we showed the general framework of compositional studies. Literature for compositional studies of GM crops conducted abroad and in Korea was reviewed to obtain information about analytes, conventional counterparts, cultivation year, location, and statistical methods. The studies conducted abroad assessed for commercial release of GM crops such as soybean, maize, and cotton, while domestic studies were mainly performed for research in rice. In addition, we suggested a guidance for conventional comparators and field trials applicable to the domestic situation.