PURPOSES : In this study, drone highway route alternatives were evaluated using the analytic hierarchy process (AHP) technique to investigate any difficulties or improvements while designing drone highway routes. METHODS : Based on the literature review and AHP analysis, 39 road and airport experts were surveyed to evaluate two alternate drone highway routes that connect the Seoul train station and Jamsil park near Gangnam business district. RESULTS : The AHP analysis results revealed that the environmental aspect was the most critical factor in designing a drone highway route, followed by social and technological factors. Among the investigated factors, noise and life-environment showed the highest geometric mean value of 0.21. This mean should be considered when developing plans and policies for drone highway design. CONCLUSIONS : Environmental and social agreement is more crucial than the technological and economic aspects when designing drone highway routes. Laws and policies should be updated and followed to support the drone highway system, which is vital in logistics.

PURPOSES: The purpose of this study is to evaluate different types of Ground Penetrating Radar (GPR) testing for characterizing the road cavity detection. The impulse and step-frequency-type GPR tests were conducted on a full-scale testbed with an artificial void installation. After analyzing the response signals of GPR tests for detecting the road cavity, the characteristics of each GPR response was evaluated for a suitable selection of GPR tests. METHODS: Two different types of GPR tests were performed to estimate the limitation and accuracy for detecting the cavities underneath the asphalt pavement. The GPR signal responses were obtained from the testbed with different cavity sizes and depths. The detection limitation was identified by a signal penetration depth at a given cavity for impulse and step-frequency-type GPR testing. The unique signal characteristics was also observed at cavity sections. RESULTS: The impulse-type GPR detected the 500-mm length of cavity at a depth of 1.0 m, and the step-frequency-type GPR detected the cavity up to 1.5 m. This indicates that the detection capacity of the step-frequency type is better than the impulse type. The step-frequency GPR testing also can reflect the howling phenomena that can more accurately determine the cavity. CONCLUSIONS : It is found from this study that the step-frequency GPR testing is more suitable for the road cavity detection of asphalt pavement. The use of step-frequency GPR testing shows a distinct image at the cavity occurrences.

PURPOSES: Pavement Management System contains the data that describe the condition of the road. Under limited budget, the data can be utilized for efficient plans. The objective of this research is to develop a mixed integer program model that maximizes remaining durable years (or Lane-Kilometer-Years) in road maintenance planning. METHODS: An optimization model based on a mixed integer program is developed. The model selects a cluster of sectors that are adjacent to each other according to the road condition. The model also considers constraints required by the Seoul Metropolitan Facilities Management Corporation. They select two lanes at most not to block the traffic and limit the number of sectors for one-time construction to finish the work in given time. We incorporate variable cost constraints. As the model selects more sectors, the unit cost of the construction becomes smaller. The optimal choice of the number of sectors is implemented using piecewise linear constraints. RESULTS: Data (SPI) collected from Pavement Management System managed by Seoul Metropolitan City are fed into the model. Based on the data and the model, the optimal maintenance plans are established. Some of the optimal plans cannot be generated directly in existing heuristic approach or by human intuition. CONCLUSIONS: The mathematical model using actual data generates the optimal maintenance plans.

본 연구는 전라남도와 경상남도의 4개 시.군에서 개설 후 1∼15년 경과한 임도에서 경과년수별로 절토 사면에 조사구를 설치하고. 식생조사와 환경인자를 조사하였다. 경과년수에 따라 침입하는 종 수와 피복도는 점차 증가하였으며, 초본류의 출현비율은 감소하였고, 목본류의 출현비율은 증가하였다. Ordination 분석을 실시한 결과 종의 분포에 영향을 미치는 요인은 시공 후 경과년수, 절토경사, 해발고, 절토사면 방향 등으로 나타났다. 임도사면의 녹화를 위해서는 시공 초기에 파종하던 종 이외에 쑥. 뱀딸기, 참억새, 칡, 산초나무, 붉나무, 병꽃나무 등이 적합할 것으로 판단된다. 임도사면에 출현한 관속식물은 77과 190속 233종 38변종으로 총 271종이며. 그 중 귀화식물은 18종이 출현하였다. 출현종의 빈도 우선순위를 보면. 산딸기, 쑥, 산초나무, 칡, 소나무. 조록싸리, 큰까치 수영, 싸리. 이고들빼기. 참억새, 개망초 등의 순이다.