• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.3
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• pp.68-77
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• 2011

Flood disasters on the metropolis where population and facilities were densely concentrated cause an enormous damage, therefore it is important to find risk and vulnerable area for floods, and then mid-long term disaster reduction plan should be established by the results. However, there is no rational method which reflects urban characteristics to estimate the regional safety for flood. so it is necessary to develop the standardized method of regional safety assesment due to urban flood. The proposed regional safety assesment model in this study was combined risk and mitigation score which consisted of three and two element, and 12 assesment factors which effect flood disasters were selected. And then the integrated regional safety was estimated by subtracting mitigation score from risk score. GIS tool was used to estimate the factor assesment and integrated regional safety. Developed regional safety assesment model was applied in Seoul to evaluate the suitability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.12
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• pp.942-952
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• 2018

A wireless power transfer (WPT) system for an urban railroad is currently under development in S. Korea. This system supplies power to railroad cars using 60 kHz magnetic fields. The electromagnetic fields (EMFs) generated by the WPT system should satisfy established safety requirements for exposure of the human body to these fields. However, EMF measurements and the safety assessment methods for fields generated by the WPT system have not yet been established. As such, a measurement and safety assessment method for EMF generated by a WPT system for an urban railroad is proposed in this report. The EMF generated by this WPT system on a test railroad was measured and compared to the reference level set by the human safety standard for EMF exposure.

• International Journal of Railway
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• v.4 no.4
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• pp.81-85
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• 2011

This paper discusses the development of a generic train operation model from a set of Korean Urban Transit Regulations such as Regulation for Train Operation of Urban Transit, Regulation for Safety Requirements of Urban Transit and so on. It is to communicate with various stakeholders on urban transit system, and to elicit copious requirements in performance of the urban transit train operation based on the model.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2008.11a
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• pp.222-225
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• 2008

In urban life, an interest in safety and demands for safety information about crimes and traffic are increasing. As well, communication on the internet is so active. In this study, we analyze web sites in US, UK, and JP, which have started safety map services, and then we provide basic material for the introduction of safety map into Korea. According to the analysis result, in US and UK, the safety map web sites are administered by the government and provided to the general public. The geographical area is provided around administrative districts and statistical data. In JP, The safety map web site provide not a one sided service but the service that user can directly take a part in, and also there is an web site for crimes against vulnerable people.

• Journal of the Korean Society of Safety
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• v.26 no.6
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• pp.111-117
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• 2011

Risk-based railway safety management has been mandatory in Korea as by relevant laws and regulations enacted since the Railway Safety Act 2004. In particular, the Railway Vehicle Safety Guidance came into effect on Jan 1, 2008 specifies the details of methodology for hazard analysis, risk assessment and safety verification and validation. Fundamentals for success of the risk-based safety management are systematic hazard identification and risk assessment by use of reasonable risk assessment criteria, but the principle of risk-based safety management has not been applied in an effective way to introduction and maintenance of railway vehicle systems because definite risk assessment criteria have not been set down for each railway system or railway network. The purpose of this study is to suggest a risk matrix development principle for risk assessment of domestic urban metro vehicles by analyses of relevant rules and railway operating environment of Korea.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.2
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• pp.219-224
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• 2016

Objectives: Lung cancer occurred with worker working in an urban bus garage. A survey was conducted to investigate whether lung cancer had causal relationship with work. Exposure to asbestos and diesel engine exhaust were suspected. Methods: Airborne asbestos was sampled on membrane filter and analyzed using phase-contrast microscopy. Airborne diesel exhaust was sampled using quartz filter and analyzed with thermal-optical analyzer. Polynuclear aromatic hydrocarbons was sampled using PTFE filter and XAD-2 tube and analyzed with gas chromatography-mass selective detector. Results: Airborne asbestos concentration was under 0.01 fiber/cc. Worker who warmed up an engine of urban bus for 2 hours was exposed to elemental carbon concentration, $15.5{\mu}g/m^3$. Only naphtalene among polynuclear aromatic hydrocarbons was detected. Conclusions: It was difficult to conclude about worker exposure to asbestos because working hour related asbestos was too short. In reviewing papers, the exposure to asbestos over 0.01 fiber/cc during exchange brake lining was found. It was identified that worker's occupational exposure to diesel exhaust based on elemental carbon was higher than the other occupational exposure to diesel exhaust.

• Structural Monitoring and Maintenance
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• v.5 no.4
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• pp.489-506
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• 2018

This paper reported test of full-scale cables attached with four types of dampers: viscous damper, passive Magneto-Rheological (MR) damper, friction damper and High Damping Rubber (HDR) damper. The logarithmic decrements of the cable with attached dampers were calculated from free vibration time history. The efficiency ratios of the mean damping ratios of the tested four dampers to theoretical maximum damping ratio were derived, which was very important for practical damper design and parameter optimization. Non-ideal factors affecting damper performance were discussed based on the test results. The effects of concentrated mass and negative stiffness were discussed in detail and compared theoretically. Approximate formulations were derived and verified using numerical solutions. The critical values for non-dimensional concentrated mass coefficient and negative stiffness were identified. Efficiency ratios were approximately 0.6, 0.6, and 0.3 for the viscous damper, passive MR damper and HDR damper, respectively. The efficiency ratio for the friction damper was between 0-1.0. The effects of concentrated mass and negative stiffness on cable damping were positive as both could increase damping ratio; the concentrated mass was more effective than negative stiffness for higher vibration modes.

• Environmental Engineering Research
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• v.24 no.1
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• pp.107-116
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• 2019

Nitrogen removal, nitrous oxide ($N_2O$) emission and microbial community in sequencing batch and continuous-flow intermittent aeration processes were investigated. Two sequencing batch reactors (SBRs) and two continuous-flow multiple anoxic and aerobic reactors (CMRs) were operated under high dissolved oxygen (DO) (SBR-H and CMR-H) and low DO (SBR-L and CMR-L) concentrations, respectively. Nitrogen removal was enhanced under CMR and low DO conditions (CMR-L). The highest total inorganic nitrogen removal efficiency of 91.5% was achieved. Higher nitrifying and denitrifying activities in SBRs were observed. CMRs possessed higher $N_2O$ emission factors during nitrification in the presence of organics, with the highest $N_2O$ emission factor of 60.7% in CMR-L. SBR and low DO conditions promoted $N_2O$ emission during denitrification. CMR systems had higher microbial diversity. Candidatus Accumulibacter, Nitrosomonadaceae and putative denitrifiers ($N_2O$ reducers and producers) were responsible for $N_2O$ emission.

• Smart Structures and Systems
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• v.23 no.6
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• pp.669-682
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• 2019

Vibration mitigation of cables or hangers is one of the crucial problems for cable supported bridges. Previous research focused on the behaviors of cable with dampers or crossties, which could help engineering community apply these mitigation devices more efficiently. However, less studies are available for hybrid applied cross-ties and dampers, especially lack of both analytical and experimental verifications. This paper studied damping and frequency of two parallel identical cables with a connection cross-tie and an attached damper. The characteristic equation of system was derived based on transfer matrix method. The complex characteristic equation was numerically solved to find the solutions. Effects of non-dimensional spring stiffness and location on the maximum cable damping, the corresponding optimum damper constant and the corresponding frequency of lower vibration mode were further addressed. System with twin small-scale cables with a cross-link and a viscous damper were tested. The damping and frequency from the test were very close to the analytical ones. The two branches of solutions: in-phase modes and the out-of-phase modes, were identified; and the two branches of solutions were different for damping and frequency behaviors.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.226-228
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• 2007

The standardization system in Urban Transit is the system that verifies and develop the standard, a safety standard, a performance test standard and a Quality certification standard to improve the capability, the safety and operational efficiency and that develops technologies of the main installations. We have already developed a signal, electric power in Urban Transit. Also, we have already noticed the standardization of railroad tracks and developed the main installations through the first stage in the standardization in 1995${\sim}$2006. Still, there remains many fields to standardize, like information and communication facilities, facilities in the station, governmental organizations and maintenance facilities because, Urban Transit is so widespread. In case that we do not keep promoting the standardization in Urban Transit, rather it could hamper development of the Urban Transit. So, it is important to maintain and advance the standardization in Urban Transit. In this paper, we suggest the research course that we would promote, to maintain and develop the standardization in Urban Transit.