• Title/Summary/Keyword: optimal route

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A Study on Link Travel Time Prediction by Short Term Simulation Based on CA (CA모형을 이용한 단기 구간통행시간 예측에 관한 연구)

  • 이승재;장현호
    • Journal of Korean Society of Transportation
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    • v.21 no.1
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    • pp.91-102
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    • 2003
  • There are two goals in this paper. The one is development of existing CA(Cellular Automata) model to explain more realistic deceleration process to stop. The other is the application of the updated CA model to forecasting simulation to predict short term link travel time that takes a key rule in finding the shortest path of route guidance system of ITS. Car following theory of CA models don't makes not response to leading vehicle's velocity but gap or distance between leading vehicles and following vehicles. So a following vehicle running at free flow speed must meet steeply sudden deceleration to avoid back collision within unrealistic braking distance. To tackle above unrealistic deceleration rule, “Slow-to-stop” rule is integrated into NaSch model. For application to interrupted traffic flow, this paper applies “Slow-to-stop” rule to both normal traffic light and random traffic light. And vehicle packet method is used to simulate a large-scale network on the desktop. Generally, time series data analysis methods such as neural network, ARIMA, and Kalman filtering are used for short term link travel time prediction that is crucial to find an optimal dynamic shortest path. But those methods have time-lag problems and are hard to capture traffic flow mechanism such as spill over and spill back etc. To address above problems. the CA model built in this study is used for forecasting simulation to predict short term link travel time in Kangnam district network And it's turned out that short term prediction simulation method generates novel results, taking a crack of time lag problems and considering interrupted traffic flow mechanism.

Dynamic traffic assignment based on arrival time-based OD flows (도착시간 기준 기종점표를 이용한 동적통행배정)

  • Kim, Hyeon-Myeong
    • Journal of Korean Society of Transportation
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    • v.27 no.1
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    • pp.143-155
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    • 2009
  • A dynamic traffic assignment (DTA) has recently been implemented in many practical projects. The core of dynamic model is the inclusion of time scale. If excluding the time dimension from a DTA model, the framework of a DTA model is similar to that of static model. Similar to static model, with given exogenous travel demand, a DTA model loads vehicles on the network and finds an optimal solution satisfying a pre-defined route choice rule. In most DTA models, the departure pattern of given travel demand is predefined and assumed as a fixed pattern, although the departure pattern of driver is changeable depending on a network traffic condition. Especially, for morning peak commute where most drivers have their preferred arrival time, the departure time, therefore, should be modeled as an endogenous variable. In this paper, the authors point out some shortcomings of current DTA model and propose an alternative approach which could overcome the shortcomings of current DTA model. The authors substitute a traditional definition for time-dependent OD table by a new definition in which the time-dependent OD table is defined as arrival time-based one. In addition, the authors develop a new DTA model which is capable of finding an equilibrium departure pattern without the use of schedule delay functions. Three types of objective function for a new DTA framework are proposed, and the solution algorithms for the three objective functions are also explained.

Multi-hop Routing Protocol based on Neighbor Conditions in Multichannel Ad-hoc Cognitive Radio Networks (인지 무선 애드혹 네트워크에서의 주변 상황을 고려한 협력적 멀티홉 라우팅 방법)

  • Park, Goon-Woo;Choi, Jae-Kark;Yoo, Sang-Jo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.4A
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    • pp.369-379
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    • 2011
  • During the routing process between nodes on the CR(Cognitive Radio) network conducting for efficient use of limited frequency resources, spectrum handover process due to the appearance of the PU occupies most of the routing latency, and also decreases the reliability of the path. In this paper, a cooperative routing protocol in a multi-channel environment is proposed. The source node broadcasts a message with available channel lists and probability of PU appearance during its route guidance. The intermediate nodes re-transmit the message, received from the source node, and update and maintain the information, status table of the path. The destination node determines the optimal path and sends a reply message to the selected path after it receives the messages from the intermediate nodes. The average probability of the PU appearance and the average time of the PU appearance are updated while transferring data. During data transmission the channel with the lowest probability of appearance of the PU is selected dynamically and if a PU appears on the current channel partial repairment is performed. It is examined that reliability of the selected path considerably is improved and the routing cost is reduced significantly compared to traditional routing methods.

Preoperative Chemotherapy in Gastric Cancer (위암의 선행화학 요법)

  • Hong, Young-Seon;Park, Cho-Hyun
    • Journal of Gastric Cancer
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    • v.5 no.3 s.19
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    • pp.139-145
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    • 2005
  • Gastric cancer is the most prevalent cancer in Korea and comprises the second cause of cancer death. Surgery only can provide chance of cure, but most locally advanced cancers recur after a curative resection, even though important advances in the surgical and nonsurgical treatments of gastric cancer have taken place. Preoperative chemotherapy theoretically can provide the advantages of reducing the bulk of tumor, which might improve the R0 resection rate, and of treating micrometastases early. Also, preoperative chemotherapy is expected to render unresectable tumors resectable without increasing postoperative morbidity and mortality. There are many new chemo-therapeutic agents available for the treatment of advanced gastric cancer, but still the most effective agent, the optimal time and number of cycle for administration are still not known. The addition of postoperative chemotherapy through an intraperitoneal route and/or radiotherapy might affect the outcome of surgery favorably, but that hasn't been proved yet. A multicenter prospective randomized phase III trial should be peformed to answer for those questions and to improve the curability of gastric cancer treatment.

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Track Models Generation Based on Spatial Image Contents for Railway Route Management (철도노선관리에서의 공간 영상콘텐츠 기반의 궤적 모델 생성)

  • Yeon, Sang-Ho;Lee, Young-Wook
    • Proceedings of the KSR Conference
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    • 2008.11b
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    • pp.30-36
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    • 2008
  • The Spatial Image contents of Geomorphology 3-D environment is focused by the requirement and importance in the fields such as, national land development plan, telecommunication facility management, railway construction, general construction engineering, Ubiquitous city development, safety and disaster prevention engineering. The currently used DEM system using contour lines, which embodies geographic information based on the 2-D digital maps and facility information has limitation in implementation in reproducing the 3-D spatial city. Moreover, this method often neglects the altitude of the rail way infrastructure which has narrow width and long length. There it is needed to apply laser measurement technique in the spatial target object to obtain accuracy. Currently, the LiDAR data which combines the laser measurement skill and GPS has been introduced to obtain high resolution accuracy in the altitude measurement. In this paper, we tested of the railway facilities using laser surveying system, then we propose data a generation of spatial images for the optimal manage and synthesis of railway facility system in our 3-D spatial terrain information. For this object, LiDAR based height data transformed to DEM, and the realtime unification of the vector via digital image mapping and raster via exactness evaluation is transformed to make it possible to trace the model of generated 3-dimensional railway model with long distance for 3D tract model generation. As the results, We confirmed the solutions of varieties application for railway facilities management using 3-D spatial image contents.

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A study on the effect of blasting vibration and the optimal blasting offset according to the depth of tunnel (터널 심도에 따른 발파 진동 영향 및 최적 발파 이격거리 연구)

  • Kong, Suk-Min;Choi, Sang-Il;Kim, Yeong-Bae;Noh, Won-Seok;Kim, Chang-Yong;Lee, Seong-Won
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.24 no.6
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    • pp.483-494
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    • 2022
  • Owing to the saturation of ground spaces in downtown areas, underground spaces are being developed increasingly. Underground spaces are utilized for transportation, water supply and sewerage, communication zones, electric power zones, and various cultural complexes. In Korea, for excavating underground spaces, blasting methods using gunpowder such as the New Austrian Tunneling Method (NATM) are mainly used. However, the blasting method causes vibration and noise during tunnel excavation, generating many complaints from residents in the vicinity of the excavation site. To address this problem, various methods have been developed, and recently, vibration and noise have been reduced using deep excavation. This study predicts blast vibration changes according to the depth, under the same blasting and tunnel conditions, using numerical analysis based on the blast vibration measurement data of the GTX-A route, the tunnel cross-section drawings, and ground investigation reports. Furthermore, the necessary separation distance from densely populated areas such as residential areas is suggested by analyzing the trend of decreasing blast vibration according to the distance from ground surface directly above the blasting location.

Service Scenario Development for Customized Evacuation Route Guidance Service in Regular Building (일반건물 맞춤형 대피동선 안내 서비스를 위한 서비스 시나리오 개발 사례연구)

  • Kim, Tae Wan;Lee, Sang Ki;Shin, Dong Min;Lee, Sung Pil
    • Journal of Service Research and Studies
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    • v.8 no.4
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    • pp.13-29
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    • 2018
  • The final goal of this study was to develop an optimal service scenario to ensure that building occupants can be effectively evacuated from the building within the golden time without extra assistance in preparing and evacuating for fires. In addition, the research was carried out by dividing the current services into fire evacuation and preparedness phases by applying the Double Diamond process in order to find a way to better familiar them as a lifestyle and to always be prepared for fires. For the building occupants and managers, a total of 14 ideas were first suggested, including not only the services of how to evacuate from a fire, but also the life-style service functions associated with fire implementation technology in daily life. The 14 proposed ideas were conducted by the Service quality evaluation and Analytical Hierarchy Process(AHP) from the perspective of the service recipient, and those were finally prioritized from the service provider's perspective, taking into account the cost and practicality of the service provider. The results of this study show that differences in the importance of fire phases considered by stakeholders and the perception of fire generally vary considerably.

Research on Analytical Technique for Satellite Observstion of the Arctic Sea Ice (극지 해빙 위성관측을 위한 분석 기술 개발)

  • Kim, Hyun-cheol;Han, Hyangsun;Hyun, Chang-Uk;Chi, Junhwa;Son, Young-sun;Lee, Sungjae
    • Korean Journal of Remote Sensing
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    • v.34 no.6_2
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    • pp.1283-1298
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    • 2018
  • KOPRI(Korea Polar Research Institute) have researhed Arctic sea ice by using satellite remote sensing data since 2017 as a mission of KOPRI. The title of the reseach is "Development of Satellite Observation and Analysis for Arctc sea-ice". This project has three major aims; 1) development of prototype satellite data archive/manage system for Arctic sea ice monitoring, 2) development of sea ice remote sensing data processing and analysis technique, and 3) development of international satellite observing network for Arcitc. This reseach will give us that 1) deveolpment of sea ice observing system for northern sea route, 2) development of optimal remote sensing data processing technique for sea ice and selected satelite sensors, 3) development of international satellite onbservation network. I hope that this letter of introducton KOPRI satellite program for Arctic will help to understand Arctic remote sensing and will introduce you to step into the Arctic remote sensing, which Iis like a blue ocean of remote sensing.

A Prioritization Method Considering Trip Patterns to Introduce Short-turn Buses (단거리 순환버스 도입을 위한 통행패턴 기반의 우선순위 결정방법)

  • Moon, Sedong;Kim, Dong-Kyu;Cho, Shin-Hyung
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.18 no.5
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    • pp.1-18
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    • 2019
  • A short-turn bus is a bus that is operated within a subsection of an existing bus line. Previous studies regarding short-turn buses decided optimal turn-back points for a single bus line rather than a bus network. Also, in-vehicle crowding which has a significant impact on transit convenience was rarely considered. Therefore, this study aimed to develop a methodology to set priorities for the introduction of short-turn buses of bus lines and sections, considering crowding. To achieve this objective, we calculated occupancies and crowding alleviation benefits of existing bus lines overlapping a new short-turn route based on transit card data, before and after the introduction of short-turn strategy. Also, operator and social costs caused by the introduction of short-turn buses were calculated. Those procedures were iterated over bus lines and sections to operate a short-turn service, and a section whose benefit-to-cost ratio (B/C) is the largest in a line was selected to operate a short-turn service in the line. After, priorities of bus lines to introduce short-turn services could be determined based on B/C values, and the optimum total fleet size could be determined when a short-turn strategy is applied in multiple lines.

A Study on the Extratropical Cyclones in the North Pacific Ocean during the Winter Season for Safe Navigation of Ships (선박의 안전항해를 위한 겨울철 북태평양의 온대저기압에 관한 연구)

  • Ko, Nan-Young;Seol, Dong-Il
    • Journal of Navigation and Port Research
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    • v.44 no.6
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    • pp.447-452
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    • 2020
  • Extratropical cyclone in winter season is very important in safe operation of ships because it is a major cause of marine accidents due to its strong power. In this study, we used meteorological data, to analyze extratropical cyclones occurring near the 1st Pacific polar front from December 2019 to February 2020. The analysis results are as follows. During those three months, we recorded 41 extratropical cyclones, 8 of which were remarkably developed. The central pressure of the strongest cyclone was 947hPa. The highest number of cyclones were generated in the East P acific Ocean around J apan (16), followed by the areas around Korea, the East China Sea, and the southern Sea of J apan. The cyclones followed five major tracks with a common northeast pattern. We thus concluded that the optimal route for a ship encountering an extratropical cyclone in the North P acific in winter would be south of the cyclone's center traveling eastbound and north of the center traveling westbound.