• International Journal of Highway Engineering
• /
• v.19 no.6
• /
• pp.191-199
• /
• 2017

PURPOSES : The objective of this study is to develop a methodology to estimate the minimum required separation distance (MRSD) between a vehicle and a bicycle when overtaking. METHODS : Three steps have been conducted to develop a methodology to estimate MSRD. First, a literature review has been conducted on the measurement of MSRD, and how it may be applied in Korea. Second, two assumptions have been made to develop a methodology to estimate the MSRD. The first assumption is that the maximum separation distance between a vehicle and a bicycle can be observed when they are at the same location longitudinally. In addition, it is assumed that the separation distance is invalid when the contra-flow exists. Finally, three cameras were installed at a height of 10 m to record the vehicle-bicycle interaction. Moreover, the vehicle trajectories as well as the separation distance were coded and analyzed. Through the hypothesis test and the interval estimation, the sample mean was tested and the confidence interval was estimated. RESULTS : 141 records of separation distance data were collected, and the hypothesis test demonstrated that the MSRD in Korea is significantly higher than other countries. In addition, the confidence interval of the population mean of MSRD is from 1.51 m to 1.65 m with 95% level of confidence. CONCLUSIONS : It is expected that the proposed methodology to estimate MSRD would be beneficial in studying road safety of vehicles and bicycles. Also, the proposed MSRD is expected to be designated in the act of road and transportation.

• Journal of Korean Society of Transportation
• /
• v.32 no.5
• /
• pp.452-461
• /
• 2014

Conventional parking survey has been usually performed by a person, which has a lot of problems such as decreased mobility, data input error, longer time and expensiveness. Therefore, this study attempted to develop an automatic parking survey method using lately commercialized equipments that were highly efficient imagery interpretation equipments, GPS, and infrared lighting fixtures. In addition, this study developed a parking analysis software that enables to modify and save data, and analyze survey data by the automatic parking survey method. When parking survey is conducted using automatic parking survey method, surveying accuracy is influenced by the running speed of a surveying vehicle, the photographing angle of an imagery interpretation equipment, the gap between parking vehicles and the distance of a surveying vehicle to parking vehicles. Therefore, this study drew optimum conditions by testing on each items for accuracy improvement, and developed a parking analysis software for systematic storage and management of parking survey data, supporting the parking analysis and output the parking analysis result.

• Journal of the Korean GEO-environmental Society
• /
• v.13 no.10
• /
• pp.85-94
• /
• 2012

Recent development trend of construction projects in the urban area is the efficient use of insufficient land, however caused to difficult construction conditions because of many adjacent structures. This paper presents the case study that analyzed the ground settlement of railroad structure for the double track railway project of Gyeongui line, adjacent to the high rise building under ground excavating for substructure work, considering interaction of soft ground characteristics. Field survey and measurement works were carried out during construction of station and excavation of high rise building, and field data were analyzed to find the source of settlement of platform and railway. In addition, the soil reinforcement and foundation restoration were performed using in-situ injection method, i.e., D-ROG(Digitalized Restoring On Grout) method which filled the pore of bottom and around of foundation with micro-cement.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.3
• /
• pp.61-72
• /
• 2002

This paper presents the results of investigation on the behavior of soil-reinforced segmental retaining walls in tiered arrangement using the finite element method of analysis. 2D finite element analyses were performed on tiered walls with two levels of offset distance. Cases with equivalent surcharge as suggested by the NCMA design guideline were additionally analyzed in an attempt to confirm the appropriateness of the equivalent surcharge model adopted by NCMA. Deformation characteristics of a tiered wall with small offset distance suggest a compound mode of failure and support current design approaches requiring a global slope stability analysis for design. Also revealed is that the interaction between the upper and lower walls significantly affects not only the performance of the lower wall but also the upper wall, suggesting that the upper walls should also be designed with due consideration of the interaction.

• Fire Science and Engineering
• /
• v.23 no.5
• /
• pp.153-160
• /
• 2009

This study aims to review the propagation characteristics of fire alarm sound in building through computer simulation. In order to achieve this goal, the sound power level of existing three different emergency alarms were measured in an anechoic chamber. Sound power level of alarm bell was 98.6dB and electronic-siren speaker was 95.7dB, and electronic-siren phon was 101.8dB at the voltage of DC 24V in the condition of anechoic chamber. As the results of acoustic simulation, it was shown that sound levels at the corridor of the building were relatively high and even. But, there were large difference in sound level at all the frequency bands between corridor and lecture rooms. This mean that alarm sound couldn't be recognized sometimes in lecture rooms. Through the computer simulation, the propagation characteristics of fire alarm sound could be forecasted and compared due to plans of buildings.

• Fire Science and Engineering
• /
• v.33 no.4
• /
• pp.121-129
• /
• 2019

The Chemical Control Act of 2015 was enhanced to ensure the safe management of hazardous chemicals. In particular, there have been substantial changes in the standards for the installation and management of handling facilities for manufacturing and storing hazardous chemicals. However, some standards for handling facilities are difficult to implement due to a lack of physical space or because of safety accidents during facility improvements. Therefore, the Safety assessment system (SAS) has been operating for such facilities since 2018. This study developed a leakage trajectory evaluation module that can easily evaluate the outside of a dike for safety evaluation. We analyzed two case studies on a dike for hydrochloric acid and sulfuric acid storage tanks with this module and suggest a reasonable plan for the facility. We believe that it will be possible to more easily submit SAS reports at chemical plants by using this evaluation module. This study is expected to contribute to the improvement of the safety design of hazardous chemical handling facilities.

• Journal of Satellite, Information and Communications
• /
• v.5 no.2
• /
• pp.57-63
• /
• 2010

Many efficient frequency sharing methods are issued in present because of increasing users with various wireless communication terminals. In the satellite communications, the service coverage is generally very wide so frequency sharing with terrestrial system is essentially needed, and the research is progressing dynamically related on this frequency sharing method. But if we adopt the terrestrial system which is commonly used, it can't avoid the interference from terrestrial service to satellite service. Therefore, this paper will introduce methods for reducing the interference from terrestrial station to earth station using cognitive radio system Satellite system is guaranteed with decreasing interference from terrestrial stations using Genetic Algorithm based power control method. Furthermore, terrestrial systems can have increased QoS because the frequency reuse factor in proposed method is higher than existing methods.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.3
• /
• pp.409-426
• /
• 2001

Absorbed power of the human head radiated from a 900 MHz portable phone and temperature rise are computed using FDTD(Finite-Difference Time-Domain) method. For this computation the 5 layered media for the human head modeling and the monopole antenna attached to metallic box for the portable phone are used. To reflect the real circumstances typical sizes of human heads and portable phones are considered in the calculation. The length of monopole antenna is 8.15 cm, and the output power of a phone is 600 mW. Under the predetermined model the distribution of 1 g, 10 g averaged SAR and temperature rise rate over the human head are calculated, from which it was found that the position of maximum SAR is near at the head skin surface, not deep places far into the head. The position of the highest temperature is located far from the head skin more than that of the maximum SAR occured. The averaged SAR and temperature along the distance between the head and phone are calculated according to seperation distance between the head and phone.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.12
• /
• pp.1044-1049
• /
• 2015

In this paper, isolation enhanced antenna using isolating resonator was proposed. Two loop type antennas were designed to operate at Wi-Fi band(2.4~2.5 GHz), in symmetry to the center, and are closely located to each other. In order to enhance isolation characteristics at Wi-Fi bands, isolating resonator was designed between the two loop type antennas. The proposed isolating resonator is a slot type antenna that enhances isolation with the control of the size, and by adjusting the value of capacitor($C_D$) the resonant frequency of the isolating resonator can easily be adjusted to enhance isolation characteristic at the target frequency.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.1 s.74
• /
• pp.31-39
• /
• 2007

Recently, the nonlinear dynamic responses among waves, submarine pipeline and seabed have become a target of analyses for marine geotechnical and coastal engineers. Specifically, the velocity field around the submarine pipeline and the wave-induced responses of soil, such as stress and strain inside seabed, have been recognized as dominant factors in discussing the stability of submarine pipeline. The aim of this paper is to investigate nonlinear dynamic responses of soil in seabed, around submarine pipeline, under wave loading. In order to examine wave-induced soil responses, first, the calculation is conducted in the whole domain, including wave field and the seabed, using the VOF-FDM method. Then, velocities and pressures, which are obtained on the boundary between the wave field and the seabed, are used as the boundary condition to compute the wave-induced stress and strain inside seabed, using the poro-elastic FEM model, which is based on the approximation of the Biot's equations. Based on the numerical results, the characteristics of wave-induced soil responses around submarine pipeline are investigated, in detail, inrelation to relative separate distance of the submarine pipeline from seabed. Also, the velocity field around the submarine pipeline is discussed.