• Geomechanics and Engineering
• /
• v.13 no.3
• /
• pp.371-384
• /
• 2017

Physical and mechanical properties of rocks are of interest in many fields, including materials science, petrophysics, geophysics and geotechnical engineering. Uniaxial compressive strength UCS is one of the key mechanical properties, while density and porosity are important physical parameters for the characterization of rocks. The economic interest of carbonate rocks is very important in chemical or biological procedures and in the field of construction. Carbonate rocks exploitation depends on their quality and their physical, chemical and geotechnical characteristics. A fast, economic and reliable technique would be an evolutionary advance in the exploration of carbonate rocks. This paper discusses the ability of ultrasonic wave velocity to evaluate some mechanical and physical parameters within carbonate rocks (collected from different regions within Tunisia). The ultrasonic technique was used to establish empirical correlations allowing the estimation of UCS values, the density and the porosity of carbonate rocks. The results illustrated the behavior of ultrasonic pulse velocity as a function of the applied stress. The main output of the work is the confirmation that ultrasonic velocity can be effectively used as a simple and economical non-destructive method for a preliminary prediction of mechanical behavior and physical properties of rocks.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.30 no.4
• /
• pp.23-32
• /
• 2022

Prototype UAMs are shown to us in the market. When the complete product is delivered to market, the efficiency of each UAMs can be compared by default. Before the complete product is shown to us, the comparative study on efficiency of UAMs is performed under the product cost estimation. The efficiency analysis result reveals that both of Lift & Cruise type and vectored thrust type show good efficiency at the initial stage of product. At the near terms stage, five years later from initial stage end, efficiency gets some change. Vectored thrust type of UAMs show best efficiency at the near term stage of product. Because UAMs will be used in urban area, Seoul is the place where the UAMs will be used first. The flying route from Seoul City Hall to Yongsan Park, National Assembly in Yeouido, and City Airport is no more than 10 km distance. For this short distance route, efficiency will make multi-rotor type UAM be prefered to other types. For long distance route or commuting route, life & cruise type and vectored thrust type of UAMs will be prefered on account of operational efficiency.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.2D
• /
• pp.193-201
• /
• 2011

The provision of traffic information plays an important role in increasing social benefit not only by saving travel time for individuals but also by improving the efficiency of road operation. VMS(Variable Message Sign) helps on-wheel drivers easily understand the road situation, and also provides real-time traffic information to people on the streets. However, it has not been sufficiently studied on how traffic information based on VMS influences on the drivers' selection of route. This study investigated how drivers use VMS traffic information and how they are satisfied with it. Then, the model of drivers' route selection was specified with the types of traffic information and the expected travel time to examine the influence on the selection of drivers' route. The model was estimated and analyzed in three types according to the condition of detour roads, and the rate of route change and the degree of sensitivity was calculated from the estimation. The results of analysis are as follows. the $1^{st}$ type model showed the 10% of route change for the travel time saving of 5minutes, and the 81.6% of route change for the travel time saving of 20minutes. The $2^{nd}$ type led to the range of route change from 14.2% to 92.7% over the 5 through 20 minutes of travel time saving. The $3^{rd}$ model resulted in the 99.1% of route change. The sensitivity of route change showed the highest for the travel time saving of 11 minutes with the $1^{st}$ type model, 9 minutes with the $2^{nd}$ type model, and 5 minutes with the $3^{rd}$ type model respectively.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.5
• /
• pp.787-797
• /
• 2021

Yellowtail Seriola quinqueradiata tagged with a Pop-up Satellite Archival Tag (PSAT) was released off the coast of near the Moseulpo, Jeju Island and the ecological data during about 40 days was obtained. However, it is difficult to determine the spatial location of underwater ecological data. To improve the accuracy of estimating the Yellowtail migration route using temperature, suitable background field of the oceanic environment data was evaluated and used for input data. After developing of the tracking algorithm for migration route estimation, three experiment cases were estimated with ecological data among the surface layer, the mixed layer, and the whole water column. All tracking experiments move from western to eastern Jeju Island. Additionally, tracking experiment using 3D ocean numerical model reveal that it is possible to estimate the migration route using the fish ecological data of the entire water column. Therefore, using a large number of ecological data and a high-accuracy ocean numerical model to estimate the migration route seems to be a way to increase the accuracy of the tracking experiment. Moreover, the tracking algorithm of this study can be applied to small pelagic fishery using small archival electronic tags to track the migration route.

• Journal of the Korea Safety Management & Science
• /
• v.21 no.4
• /
• pp.51-58
• /
• 2019

The LBS(Location Based Service) technology plays an important role in reducing wastes of time, losses of human lives and economic losses by detecting the user's location in order by suggesting the optimal evacuation route of the users in case of safety accidents. We developed an algorithm to estimate indoor location, movement path and indoor location changes of smart phone users based on the built-in sensors of smartphones and the dead-reckoning algorithm for pedestrians without a connection with smart devices such as Wi-Fi and Bluetooth. Furthermore, seven different indoor movement scenarios were selected to measure the performance of this algorithm and the accuracy of the indoor location estimation was measured by comparing the actual movement route and the algorithm results of the experimenter(pedestrian) who performed the indoor movement. The experimental result showed that this algorithm had an average accuracy of 95.0%.

• Geomechanics and Engineering
• /
• v.14 no.5
• /
• pp.453-458
• /
• 2018

Geomechanical parameters are important factors for engineering projects during design, construction and support stages of tunnel and dam projects. Geostatistical estimation methods are known as one of the most significant approach at estimation of Geomechanical parameters. In this study, Azad dam headrace tunnel is chosen to estimate Geomechanical parameters such as Rock Quality Designation (RQD) and uniaxial compressive strength (UCS) by ordinary kriging as a geostatistical method. Also Rock Mass Rating (RMR) distribution is presented along the tunnel. Main aim in employment of geostatistical methods is estimation of points that unsampled by sampled points.To estimation of parameters, initially data are transformed to Gaussian distribution, next structural data analysis is completed, and then ordinary kriging is applied. At end, specified distribution maps for each parameter are presented. Results from the geostatistical estimation method and actual data have been compared. Results show that, the estimated parameters with this method are very close to the actual parameters. Regarding to the reduction of costs and time consuming, this method can use to geomechanical estimation.

• Journal of Preventive Medicine and Public Health
• /
• v.29 no.2 s.53
• /
• pp.331-346
• /
• 1996

Exploring the epidemiological trend of HIV/AIDS is required for making the national AIDS policy. In this study, the trend of HIV/AIDS incidence, rout of transmission and some characteristics of AIDS for the past 11 years in Korea using the reported cases from the national STD screening scheme were reviewed. Based on the results, the trend of main route of transmission according to the year was established by stage and the HIV/AIDS cases in this year was estimated and that to the year 2000 was projected by 'Epimodel' programme. The results were as follows : 1. Of the total infected persons, 76% were in their twenties and thirties, socioeconomically and sexually active age groups. While the transmission by sexual contact overseas was decreasing, the infection through domestic heterosexual and homosexual contact was increasing. 2. In the middle of the 1980's, the infected persons were mainly prostitutes infected through heterosexual contact with the HIV positive foreigner in this county(stage 1). And in the late of the 1980's the main source of infection was the sexual contact overseas and the domestic heterosexual contact(stage 2). Since the early of the 1990's, the infection through the heterosexual contact with non-regular sexual partner in this country has increased rapidly(stage 3), which was the evidence of the possibility of HIV epidemics. After that, it was expected that the infection through the homosexual contacts, the heterosexual contacts with commercial sex workers outside and the non-regular sexual contact inside of this country would increase continuously. In the result, the occurrence of neonatal infection by vertical transmission was expected(stage4). 3. The number of HIV/AIDS was estimated at 572 to 2,313 and the projected number of HIV/AIDS to the you 2000 was around 5,800 including 627 AIDS patients. For the further study on the estimation and projection of HIV/AIDS, it was suggested that the sampling survey on the HIV infection rate in the high risk groups and the sentinel hospital surveillance system should be conducted.

• Journal of IKEEE
• /
• v.25 no.4
• /
• pp.756-761
• /
• 2021

Dynamic route guidance (DRG) finds the fastest path from a source to a destination location considering the real-time congestion information. In Korea, the traffic state information is available by the public transportation data (PTD) which is indexed on top of the node-link map (NLM). While the NLM is the authoritative low-detailed road network for major roads only, the OpenStreetMap road network (ORN) supports not only a high-detailed road network but also a few open-source routing engines, such as OSRM and Valhalla. In this paper, we propose a DRG framework based on road network matching between the NLM and ORN. This framework regularly retrieves the NLM-indexed PTD to construct a historical speed profile which is then mapped to ORN. Next, we extend the Valhalla routing engine to support dynamic routing based on the historical speed profile. The numerical results at the Yeoui-do island with collected 11-month PTD show that our DRG framework reduces the travel time up to 15.24 % and improves the estimation accuracy of travel time more than 5 times.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.13 no.4
• /
• pp.73-85
• /
• 2014

Approaching to aging society with increasing transportation vulnerable, most developed countries has positively promote low-floor bus. Such circumstance in Korea has plan to introduce low-floor bus to intra-city bus system which accounted for 30 percent of total number of buses however there is no specific operating plan for this matter. According to the revealed preference study on bus service, the study shows that the efficiency of low-floor is relatively low than that of other buses, therefore, it is necessary to establish feasible plan for bus route selection. Thus, this study is to conduct research on analyzing trip characteristics of transportation vulnerable and establish bus route selection measures for low-floor bus. The result from the survey in Jeollabuk-do Province reveals that the trip purpose of transportation vulnerable is mainly for welfare and medical service, which was made less than 6 times a week. Futhermore, 37.6 percent of transportation vulnerable use buses, thus, it is essential to improve its service quality for enhancing user's convenience and safety. In that transportation vulnerable O-D needs to be established and forecasts future demand for selecting optimal bus route. According to the estimation, route passing through densely populated areas with transportation vulnerable should take the first priority, city circular and other route would be next. Moreover, it is economically efficient that areas populated more than 200,000 with fixed route and less than 200,000 with limited route responsive to demands would be feasible plans. This study will have greater an impact on transportation planning and further research on transportation vulnerable.

• International Journal of Highway Engineering
• /
• v.13 no.3
• /
• pp.83-91
• /
• 2011

The objective of VMS(Variable Message Sign) is to provide the traffic information downstream to drivers upstream so that they can choose their routes or expect the travel time to arrive the destination. Because there is not enough time and space to show the message, VMS message should be selected carefully. However, the message of VMS has been simply selected among the pre-designed message sets based on the priority rule of events. If the traffic demand between origin and destination is identified along the freeway, message can be selected to provide the information of a route that more drivers will use. In this study, a time sliced OD(Origin/Destination) estimation method will be developed using the detector information of the on-ramp, exit ramp, and the main lanes. And the strategy of a priority rule of message was planned.