• International Journal of Highway Engineering
• /
• v.12 no.4
• /
• pp.79-86
• /
• 2010

This study deals with the roundabout installed at the diamond interchange. The goal is to analyze the relative effectiveness of roundabout to signalized intersection. In pursuing the above, this study gives the particular attentions to comparing the performances using VISSIM software. The main results analyzed are as follows. First, the single and double roundabouts are analyzed to have the rapid change of delay in the case of total entering vehicles of more than 2,400pcph for directional rate 10:5:5, 2,800pcph for 10:8:2, and 4,400pcph for 10:2:8. Second, the roundabouts are evaluated to be more effective than signalized intersection in the case of total entering vehicles of less than 4,000pcph for directional rate 10:5:5, and 4,400pcph for 10:2:8. In the case of directional rate 10:8:2, double roundabout of total entering vehicles less than 5,600pcph is analyzed to be more effective than signalized intersection. Finally, the performance of double roundabout is analyzed to be very similar to that of single roundabout in the case of total entering vehicles less than 4,400pcph. However, the double roundabout is evaluated to be more effective than single in the case of total entering vehicles more than 4,400pcph.

• Journal of Navigation and Port Research
• /
• v.27 no.4
• /
• pp.425-430
• /
• 2003

The satellite navigation system is widely used for identifying a user's position regardless of weather or geographic conditions and also make effect on new technology of marine LBS(Location Based Service). which has the technology of geographic information such as the ENC. Generally, there are conceivable systems of marine LBS such as ECDIS, or ECS that use the ENC itself with powerful processor in installed type on ships bridge. Since the ENC is relatively heavy structure with dummy format for data transfer between different systems, we should reduce the ENC to small and compact size in order to use it in mobile platform. In this paper, we assumed that the mobile system like PDA, or Webpad can be used for small navigation or information system in marine field. We considered the reduction of the ENC size to make them fit well to small capability of mobile platform. However, the ENC should be updated periodically by update profile data produced by HO. If we would reduce the ENC without a consideration of update, we could not get newly updated data furthermore. As summary, we studied considerations for ENC reduction with update capability. It will make the ENC be useful in many low performance platforms for various applications.

• Journal of Korean Society of Transportation
• /
• v.30 no.6
• /
• pp.93-102
• /
• 2012

The frequency and severity of traffic accidents related to signalized intersections in urban areas have been more serious than those in both arterial segments and crosswalks. Especially, traffic accidents involved with injuries and fatalities have caused by traffic signal violations within intersections. Therefore, many countries including Korea have installed the red light enforcement camera (RLE) to reduce traffic accidents associated with the traffic signal violation. Meanwhile, many methodologies have been studied in terms of safety impacts estimation of red light enforcement, which, however, cannot be easy to conduct. In this study, safety impacts was estimated for intersections of Chicago downtown area using SPF models and EB approach. As a result, for all crash types and target traffic accident types such as "angle", "rear end", "sideswipe in the same and other directions", "turn", and "head on", fatal crashes were reduced by 26% and 38%. However, RLE may increase property-demage-only-crashes by 3.23% and 1.16%, respectively.

• Journal of Korean Society of Transportation
• /
• v.30 no.6
• /
• pp.71-80
• /
• 2012

This research suggested a real-time traffic signal control algorithm using individual vehicle travel times on an isolated signal intersection. To collect IDs and passing times from individual vehicles, space-based surveillance systems such as DSRC were adopted. This research developed models to estimate arrival flow rates, delays, and the change rate in delay, by using individual vehicle's travel time data. This real-time signal control algorithm could determine optimal traffic signal timings that minimize intersection delay, based on a linear programming. A micro simulation analysis using CORSIM and RUN TIME EXTENSION verified saturated intersection conditions, and determined the optimal traffic signal timings that minimize intersection delay. In addition, the performance of algorithm varying according to market penetration was examined. In spite of limited results from a specific scenario, this algorithm turned out to be effective as long as the probe rate exceeds 40 percent. Recently, space-based traffic surveillance systems are being installed by various projects, such as Hi-pass, Advanced Transportation Management System (ATMS) and Urban Transportation Information System (UTIS) in Korea. This research has an important significance in that the propose algorithm is a new methodology that accepts the space-based traffic surveillance system in real-time signal operations.

• Korean journal of food and cookery science
• /
• v.25 no.4
• /
• pp.474-487
• /
• 2009

The principal objectives of this study were to evaluate the space, equipment, and institution rate by functional area, and to suggest appropriate types, numbers, and equipment capacity by school foodservice size for optimal employee job performance and efficiency. Data were collected and administered by 263 dietitians who attended elementary and middle schools in Gyeonggi Province, and the data were analyzed using SPSS statistical software. Among a total of 72 respondents who provided usable data, 31 (48.6%) respondents were nutrition teachers and 37 (51.4%) were part-time dietitians. The majority of the respondents reported that their foodservices were self-operating types (94.4%), and 8 meals out of 10 meals provided over a 2-week period were served as normal meals, defined as meals consisting of Bab, Kook, Kimchi, and 3 side dishes (73.6%). The mean kitchen space was $186.25\;m^2$ for 500 meals/day, $269.7\;m^2$ for 501 to 1,000 meals/day, $249.1\;m^2$ for 1001 to 1500 meals/day, and $274.87\;m^2$ for 1,500 or more meals/day. The mean space of functional areas was $11.52\;m^2$ for office, $12.63\;m^2$ for storeroom, $9.55\;m^2$ for receiving area, $27.23\;m^2$ for pre-preparation area, $149.9\;m^2$ for cooking area, $18.33\;m^2$ for assembly/service area, $45.50\;m^2$ for dishwashing area, and $17.20\;m^2$ for locker room. Only two pre-preparation and cooking spaces increased significantly with increasing size of school foodservice (p<0.05). Office, cooking area, and locker room were allocated in all foodservices. However, the pre-preparation area (68.7%), receiving area (56.5%), assembly/service area (38.1%), and dishwashing area (37.7%) were lowly installed in the surveyed facilities. Through a focus group meeting discussing the results of this study, appropriate equipment and its dimensions were suggested according to functional areas and foodservice scales. Future studies will be necessary to allocate the appropriate space by functional area with the proposed equipment requirements for optimally efficient decision making in equipment purchasing.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.9 no.4
• /
• pp.420-425
• /
• 1999

The maximum demand controller is an electrical equipment installed at the consumer side of power system for monitoring the electrical energy consumed during every integrating period and preventing the target maximum demand (MD) being exceeded by disconnecting sheddable loads. By avoiding the peak loads and spreading the energy requirement the controller contributes to maximizing the utility factor of the generator systems. It results in not only saving the energy but also reducing the budget for constructing the natural base facilities by keeping thc number of generating plants ~ninimumT. he conventional MD controllers often bring about the large number of control actions during the every inteyating period and/or undesirable loaddisconnecting operations during the beginning stage of the integrating period. These make the users aviod the MD controllers. In this paper. fuzzy control technique is used to get around the disadvantages of the conventional MD control system. The proposed MD controller consists of the predictor module and the fuzzy MD control module. The proposed forecasting method uses the SOFM neural network model, differently from time series analysis, and thus it has inherent advantages of neural network such as parallel processing, generalization and robustness. The MD fuzzy controller determines the sensitivity of control action based on the time closed to the end of the integrating period and the urgency of the load interrupting action along the predicted demand reaching the target. The experimental results show that the proposed method has more accurate forecastinglcontrol performance than the previous methods.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.10
• /
• pp.7-17
• /
• 2019

With increasing demand for large offshore infrastructures, suction cofferdams have been large, and the lid stiffener arrangement for a suction cofferdam has become a key element in cofferdam design to constrain the flexural deformation effectively. This study analyzed the changes in the structural behavior of a lid for a suction cofferdam due to lid stiffeners to provide insights into effective stiffener arrangements. By investigating conventional suction anchors, several stiffener patterns of a lid for a polygonal suction cofferdam were determined and analyzed. The structural performance of the stiffened lids was estimated by comparing the stress and deformation, and the reaction distributions on the edge of lid were investigated to analyze the effects of the stiffener arrangement on the lid-wall interface. Finite element analysis showed that radial stiffeners contribute dominantly to decreasing the stress and vertical deflection of the lids, but the stiffeners cause an increase in shear forces between the lid and wall; the forces are concentrated on the lid near the areas reinforced with radial stiffeners, which is negative to lid-wall connection design. On the other hand, inner and outer circumferential stiffeners show little reinforcement effects in themselves, while they can help reduce the stress and deformation when arranged with partial radial stiffeners simultaneously.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.10
• /
• pp.100-106
• /
• 2019

Ground and high altitude simulated combustion experiments were conducted using a liquid rocket engine with hydrogen peroxide and kerosene as the propellant. A ground and high altitude simulated combustion test facility was constructed by installing a high altitude model diffuser and TMS (Thrust Measuring System) on a vertical combustion test bench. The thrust characteristics according to altitude were investigated using the combustion test equipment. The diffuser was designed on a 1:4.8 scale to verify the characteristics of the high diffusing diffuser and starting pressure. The cold flow tests were conducted using nitrogen gas, and the performance characteristics and starting characteristics of the scale down diffuser were verified. A diffuser and TMS were installed on the vertical combustion test bench, and the thrust correction equations for the system resistance were derived. The thrust correction equations were derived from the step test and vacuum step test before the actual hot firing test. Nozzles with an operating altitude of 10km were designed. Hot firing tests were conducted to analyze the thrust characteristics according to the operating altitude changes. The actual thrust was calculated using each correction equation with the thrust value measured by the TMS.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.24 no.6
• /
• pp.745-756
• /
• 2022

The road tunnel is a semi-closed space that is blocked on all sides except the entrance and exit, and in the event of a fire, the smoke of the fire spreads longitudinally due to heat buoyancy caused by the fire and air currents that always exist in the tunnel. To solve this problem, smoke removal facilities are installed in road tunnels to secure a safe evacuation environment by controlling the direction of movement of smoke or directly smoking at fire points. In urban areas, the service level of urban roads decreases due to the increase in traffic due to the increase in population, and as a solution, the construction of underground roads in urban areas is increasing. When a fire occurs during hydrogen leakage through TPRD of a hydrogen fuel cell vehicle (FCEV), the fire intensity depends on the amount of leakage, and the maximum fire intensity depends on the orifice diameter of the TPRD. Considering the TPRD orifice diameter of 1.8 mm, this study analyzed the diffusion distance of fire smoke according to the wind speed of the roadway and the opening interval of the large exhaust port when the maximum fire intensity was 15 MW. As a result, it was analyzed that air flow in the tunnel could be controlled if the wind speed of the road in the tunnel was less than 1.25 m/s, and smoke could be controlled within 200 m from the fire if the damper interval was 50 m and 100 m.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.9 no.9
• /
• pp.721-736
• /
• 2019

In this paper, the behavior of the fire smoke due to the operation of the ventilation systems when the fire occurred in the underground station (6 basement floors) and the tunnel at the great depth was measured. Fire smoke was generated by using a smoke generator which realized heat buoyancy effect by using hot air blower. The two locations of the fire were selected on the platform and on the platform of the tunnel located outside the screen door. A ventilation mode is generally used in which smoke is exhausted through a vent hole provided in a platform when a platform fire occurs. The tests were performed by operating the exhaust through the ventilation holes of the tunnel part located at both ends of the platform. The smoke density and the wind speed/velocity were measured at various positions, and the videos were taken to analyze the movement and smoke of the smoke. In both cases for fire inside the platform and in the railway tunnel, due to the ventilation mode operation of the fan for the platform and the exhaust of the fans in the tunnel smoke were well exhausted and the smoke propagation to the area near the smoke zone was suppressed. The smoke-control mode, which is applied to both fans for the platform and fans for in the tunnel at both ends of the platform, can provide a safer evacuation environment to the passengers from the fire smoke when the platform fire or fire train stops.