• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.1
• /
• pp.67-73
• /
• 2006

10 sites in building development areas were selected and the noise level were measured by the apartment floors of apartment complex. With the fitted regression analysis, the distribution ratio($R^2$) and correction coefficient(r) was 25%(0.5) in the NIER('87) and 7.5%(0.274) in the NIER('99), respectively. The measured values of the noise level on the seventh floor of complex did not show a good agreement with the predicted noise level in the NIER('87, '99) formula. However, the developed formula demonstrated that the measured values were reasonably close to the predicted values, indicating the validity and adequacy of the predicted models with the fitted vs residual analysis in the 95% of confidence interval and 95% of predict interval. The results suggested that application of this development model obtained by the results according to the apartment floor can be improved in road traffic noise.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.12
• /
• pp.1140-1147
• /
• 2013

In this paper, The path loss model of Air Traffic Control(ATC) telecommunication radio channel has been studied at the Incheon International Airport(IIA) Cargo Terminal. We measured one frequency among VHF channel bands. The transmitting site was located at different locations with different heights. The transmitting site radiated the Continuous Wave(CW). The propagation measurement was taken using the moving vehicle equipped with receiver and antenna. The transmitting power, frequency and antenna height are the same as the current operating condition. The path loss exponent and intercept parameters were extracted by the basic path loss model and hata model. The path loss exponent at IIA Cargo terminal area were 3.67 and 3.39 respectively in first and second transmitting sites. The deviation of prediction error is 14.42 and 10.38. The new path loss equation at the IIA Cargo terminal area was also developed using the derived path loss parameters. The new path loss was compared with other models. This result will be helpful for the ATC site selection and service quality evaluation.

• Land and Housing Review
• /
• v.11 no.2
• /
• pp.95-104
• /
• 2020

This study aims to explore a purely mechanistic pavement analysis approach where viscoelasticity and fracture of asphalt mixtures are considered to accurately predict deformation and damage behavior of flexible pavements. To do so, the viscoelastic and fracture properties of designated pavement materials are obtained through experiments and a fully mechanistic damage analysis is carried out using a finite element method (FEM). While modeling crack development can be done in various ways, this study uses the cohesive zone approach, which is a well-known fracture mechanics approach to efficiently model crack initiation and propagation. Different pavement configurations and traffic loads are considered based on three main functional classes of roads suggested by FHWA i.e., arterial, collector and local. For each road type, three different material combinations for asphalt concrete (AC) and base layers are considered to study damage behavior of pavement. A concept of the approach is presented and a case study where three different material combinations for AC and base layers are considered is exemplified to investigate progressive damage behavior of pavements when mixture properties and layer configurations were altered. Overall, it can be concluded that mechanistic pavement modeling attempted in this study could differentiate the performance of pavement sections due to varying design inputs. The promising results, although limited yet to be considered a fully practical method, infer that a few mixture tests can be integrated with the finite element modeling of the mixture tests and subsequent structural modeling of pavements to better design mixtures and pavements in a purely mechanistic manner.

• Journal of the Korean Society of Safety
• /
• v.25 no.2
• /
• pp.84-88
• /
• 2010

The main point of this study is to find ways to prevent accidents at complex linear sections in advance by improving geometric structure elements that can be considered from the designing stage. Complex linear roads are consisted of sections where straight sections connect with curved sections or sections where curved sections connect with curved sections with relatively high possibility of accidents and accidents can be reduced through improving designing elements in these sections. Therefore, this study aims to develop accident forecasting model in complex linear roads and to clarify major elements affecting traffic accidents. The results of analysis showed that the groups are divided into a group less than 355m based on curve radius of 355m, a group whose curve radius exceeds 355m and a group whose incline exceeds -0.79 and a group whose curve radius is below 355m and incline exceeds -0.79 for straight section + curved section, and for curved section + curved section, it is divided into a group whose first curved section is less than 410m based on curve radius of 410m and the first curve is turning right and a group exceeding 410m and the first curve is turning left. The major variables common in 2 models are front curve radius and curve types(left, right), road surfaces, weather.

• Smart Media Journal
• /
• v.13 no.6
• /
• pp.54-61
• /
• 2024

Recently, due to the increase in domestic and international online e-commerce platforms and the increase in container traffic at domestic ports, the operating ratio of large trucks has increased, and the number of truck fires is continuously increasing. In particular, spontaneous combustion is the most common cause of truck fires. Various academic approaches have been attempted to prevent truck fires, but due to the lack of research on the spontaneous tire ignition phenomenon that occurs during braking, this research directly designed and manufactured an experimental device to establish an environment similar to the braking system of a truck. A non-contact temperature sensor was installed on the brake device of the experimental device to collect temperature data generated from the brake device. Based on the data collected from the temperature sensor of the brake device and the temperature sensor on the tire surface, the ARIMA model among the time series prediction models was used to Appropriate parameters were selected to suit the temperature change trend, and as a result of comparing and analyzing the measured and predicted data, an accuracy of over 90% was obtained. Based on this, a plan was proposed to reduce the rate of fires in trucks by providing real-time warnings and support for truck drivers to respond to overheating phenomena occurring in the braking system.

• Tunnel and Underground Space
• /
• v.9 no.4
• /
• pp.306-314
• /
• 1999

In underground spaces including nuclear waste repository, prediction of air quantity, temperature/humidity and pollutant concentration is utmost important for space construction and management during the normal state as well as for determining the measures in emergency cases such as underground fires. This study aims at developing a model for underground space environment which has capabilities to take into account the effects of autocompression for the natural ventilation head calculation, to find the optimal location and size of fans and regulators, to predict the temperature and humidity by calculating the convective heat transfer coefficient and the sensible and latent heat transfer rates, and to estimate the pollutant levels throughout the network. The temperature/humidity prediction model was applied to a military storage underground space and the relative differences of dry and wet temperatures were 1.5 ~ 2.9% and 0.6 ~ 6.1%, respectively. The convection-based pollutant transport model was applied to two different vehicle tunnels. Coefficients of turbulent diffusion due to the atmospheric turbulence were found to be 9.78 and 17.35$m^2$/s, but measurements of smoke and CO concentrations in a tunnel with high traffic density and under operation of ventilation equipment showed relative differences of 5.88 and 6.62% compared with estimates from the convection-based model. These findings indicate convection is the governing mechanism for pollutant diffusion in most of the tunnel-type spaces.

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

• International Journal of Highway Engineering
• /
• v.10 no.1
• /
• pp.63-74
• /
• 2008

Resilient deformation characteristics on unbound pavement materials have been adopted for design and nonlinear analysis of pavement structure under traffic loadings. However, relatively few studies have been done on the nonlinear resilient behavior of unbound pavement materials in Korea. In addition, only the limited information is available for estimating the resilient modulus values on unbound materials. In this study, a laboratory resilient-deformation test under repeated loadings is performed in order to fud a proper constitutive model that correlates the resilient modulus with stress state from field condition. Finally, a finite element analysis is conducted for evaluating the nonlinear characteristics of unbound materials. and the pavement performance respectively.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.142-142
• /
• 2021

An arbitrary representation of an urban drainage sewer system was devised using a geographic information system (GIS) tool in order to calculate the surface and subsurface flow interaction for simulating urban flood. The proposed methodology is a mean to supplement the unavailability of systematized drainage system using high-resolution digital elevation(DEM) data in under-developed countries. A modified DEM was also developed to represent the flood propagation through buildings and road system from digital surface models (DSM) and barely visible streams in digital terrain models (DTM). The manhole, sewer pipe and storm drain parameters are obtained through field validation and followed the guidelines from the Plumbing law of the Philippines. The flow discharge from surface to the devised sewer pipes through the storm drains are calculated. The resulting flood simulation using the modified DEM was validated using the observed flood inundation during a rainfall event. The proposed methodology for constructing a hypothetical drainage system allows parameter adjustments such as size, elevation, location, slope, etc. which permits the flood depth prediction for variable factors the Plumbing law. The research can therefore be employed to simulate urban flood forecasts that can be utilized from traffic advisories to early warning procedures during extreme rainfall events.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.49 no.7
• /
• pp.378-388
• /
• 2000

In this paper, we propose Fuzzy Polynomial Neural Networks(FPNN) based on Polynomial Neural Networks(PNN) and Fuzzy Neural Networks(FNN) for model identification of complex and nonlinear systems. The proposed FPNN is generated from the mutually combined structure of both FNN and PNN. The one and the other are considered as the premise part and consequence part of FPNN structure respectively. As the consequence part of FPNN, PNN is based on Group Method of Data Handling(GMDH) method and its structure is similar to Neural Networks. But the structure of PNN is not fixed like in conventional Neural Networks and self-organizing networks that can be generated. FPNN is available effectively for multi-input variables and high-order polynomial according to the combination of FNN with PNN. Accordingly it is possible to consider the nonlinearity characteristics of process and to get better output performance with superb predictive ability. As the premise part of FPNN, FNN uses both the simplified fuzzy inference as fuzzy inference method and error back-propagation algorithm as learning rule. The parameters such as parameters of membership functions, learning rates and momentum coefficients are adjusted using genetic algorithms. And we use two kinds of FNN structure according to the division method of fuzzy space of input variables. One is basic FNN structure and uses fuzzy input space divided by each separated input variable, the other is modified FNN structure and uses fuzzy input space divided by mutually combined input variables. In order to evaluate the performance of proposed models, we use the nonlinear function and traffic route choice process. The results show that the proposed FPNN can produce the model with higher accuracy and more robustness than any other method presented previously. And also performance index related to the approximation and prediction capabilities of model is evaluated and discussed.