• Structural Engineering and Mechanics
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• 제31권5호
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• pp.527-544
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• 2009

In this study, the periodic seismic performance evaluation scheme is proposed using a structural health monitoring system in terms of seismic fragility. An instrumented highway bridge is used to demonstrate the evaluation procedure involving (1) measuring ambient vibration of a bridge under general vehicle loadings, (2) identifying modal parameters from the measured acceleration data by applying output-only modal identification method, (3) updating a preliminary finite element model (obtained from structural design drawings) with the identified modal parameters using real-coded genetic algorithm, (4) analyzing nonlinear response time histories of the structure under earthquake excitations, and finally (5) developing fragility curves represented by a log-normal distribution function using maximum likelihood estimation. It is found that the seismic fragility of a highway bridge can be updated using extracted modal parameters and can also be monitored further by utilizing the instrumented structural health monitoring system.

• 한국철도학회논문집
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• 제9권1호
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• pp.102-109
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• 2006

The PSC girders which currently used at highway bridge have the standard cross sections about 25m, 30m and 35m span. Thus, in case of highway bridge design, the bridge designer can choose the adequate standard cross section according to constructional condition. However, in railway bridge design, there are limitations on reasonable bridge design considering circumstances of a construction site and conditions of location etc, because the PSC girders used at railway bridge have the cross section about only 25m span length. In this study, the optimum design for the PSC girder railway bridge with 30m span length has been performed. Also, in order to investigate the dynamic stability of railway bridge using the optimum section of PSC girder, dynamic analysis has been carried out. From the results of analysis, it is suggested to denote the optimum section which satisfied the structural safety, dynamic stability and economical efficiency all together.

• Geomechanics and Engineering
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• 제7권2호
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• pp.201-212
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• 2014

Due to the sea-crossing bridge span is generally large and main pier pile foundations are located in deep water and carry large vertical load, sea-crossing bridge main pier pile foundations bearing mechanism and load deformation characteristics are still vague. Authors studied the vertical bearing properties of sea-crossing bridge main pier pile foundations through pilot load tests. Large tonnage load test of Qingdao Bay Bridge main pier pile program is designed by using per-stressed technique to optimize the design of anchor pile reaction beam system. Test results show that the design is feasible and effective. This method can directly test bearing capacity of main pier pile foundations, and analysis bearing behaviors from test results of sensors which embedded in the pile. Through test study the vertical bearing properties of main pier pile foundation and compared with the generally short pile, author summarized the main pier pile foundations vertical bearing capacity and the main problem of design and construction which need to pay attention, and provide a reliable basis and experience for sea-crossing bridge main pier pile foundations design and construction.

• International Journal of Automotive Technology
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• 제7권5호
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• pp.625-635
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• 2006

From a viewpoint of human factors, automated highway systems(AHS) can be defined as one of the newly developing human-machine systems that consist of humans(drivers and operators), machines(vehicles and facilities), and environments(roads and roadside environments). AHS will require a changed vehicle control process and driver-vehicle interface(DVI) comparing with conventional driving. This study introduces a fixed-based AHS simulator and provides questionnaire-based human factors evaluation results after three kinds of automated driving speed experiences in terms of road configuration, operation policies, information devices, and overall AHS use. In the simulator, the "shared space-at-grade" concept-based road configuration was virtually implemented on a portion of the Kyungbu highway in Korea, and heads-up display(HUD), AHS information display, and variable message signs(VMS) were installed for appropriate AHS DVI implementation. As the results, the subjects expressed positive opinions on the implemented road configuration, operation policies, and the overall use of AHS. The results of this study would be helpful in developing the road configuration and DVI design guideline as the basic human factors research for the future implementation of AHS.

• Wind and Structures
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• 제30권1호
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• pp.85-97
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• 2020

The accurate estimation of the buffeting response of a bridge pylon is related to the quality of the bridge construction. To evaluate the influence of wind field characteristics on the buffeting response of a pylon in a trumpet-shaped mountain pass, this paper deduced a multimodal coupled buffeting frequency domain calculation method for a variable-section bridge tower under the twisted wind profile condition based on quasi-steady theory. Through the long-term measurement of the wind field of the trumpet-shaped mountain pass, the wind characteristics were studied systematically. The effects of the wind characteristics, wind yaw angles, mean wind speeds, and wind profiles on the buffeting response were discussed. The results show that the mean wind characteristics are affected by the terrain and that the wind profile is severely twisted. The optimal fit distribution of the monthly and annual maximum wind speeds is the log-logistic distribution, and the generalized extreme value I distribution may underestimate the return wind speed. The design wind characteristics will overestimate the buffeting response of the pylon. The buffeting response of the pylon is obviously affected by the wind yaw angle and mean wind speed. To accurately estimate the buffeting response of the pylon in an actual construction, it is necessary to consider the twisted effect of the wind profile.

• 한국도로학회논문집
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• 제16권3호
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• pp.75-84
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• 2014

PURPOSES : Traffic congestions which occur in the intersections of arterials lead to mobility and environment problem, and then traffic agencies and engineers have been struggling for mitigating congestions with greenhouse gas emissions. As an alternative of solving theses problems, this study is to introduce a low-cost and high-effectiveness countermeasure as unconventional intersections which are successfully in operation in U.S.. The main feature of unconventional intersections is to reroute turning movement on an approach to other approach, which consequently more green time is available for the progression of through traffic. Due to improved progression, this unique geometric design contributes to reduce delays with greenhouse gas emission and provides a viable alternative to interchanges. This study is to evaluate the potential operation and environment benefits of unconventional intersections. METHODS : This study used the VISSIM model with Synchro and EnViVer. Synchro is to optimize signal phases and EnViVer model to estimate the amount of greenhouse gas emissions by each condition. RESULTS : The result shows that unconventional intersections lead to increase the capacity and to reduce greenhouse gas emissions, compared to existing intersections. CONCLUSIONS : Unconventional intersections have the ability to positively impact operations and environments as a low-cost and high-effectiveness countermeasure.

• 한국산학기술학회논문지
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• 제11권5호
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• pp.1778-1784
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• 2010

본 연구는 기존의 진동 처짐에 대한 교량 사용성 평가기준 연구 내용을 바탕으로 최첨단 모의운전 차량실험기(Advanced Driving Simulator)를 이용하여 운전자가 교량 주행 시 진동으로 인해 느끼는 주행안락도를 평가하는 기준을 제안하였다. 열차승객을 대상으로 하는 Reiher-Meister Curve의 적용성을 파악하고 교량 계측결과와 구조해석 결과를 토대로 수정 Reiher-Meister Curve 제안하였다. 교량운전자 중심의 사용성 평가를 위한 수정 Reiher-Meister Curve는 A에서 D까지 4등급으로 규정되었다. 새로운 진동감각곡선은 교량 사용자 중심의 교량 설계 및 유지관리분야에 널리 사용될 수 있을 것이다.

• 설비공학논문집
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• 제11권3호
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• pp.359-368
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• 1999

The outdoor and indoor air quality surrounding highway have been measured, and the study on the design of the booth shape and the air-conditioning system also has been carried out. For the first step of the work, the air quality at the Seoul tollgate on the Kyeong-bu highway was monitored over a year. The measured indoor air quality shows seasonal average concentration 85.6-92.1ppb of >;$NO_2$and the $SO_2$and CO lower than the EAQS(Environmental Air Quality Standards). The measured TSP concentration was much higher than the EAQS. In conclusion, there is necessity to improve the working environment of the tollbooths on highways, and the current air-conditions need to be modify for the purpose. In the process of modifying the air-conditioning system, particulate pollutants needs to be considered processing and the priority needs to be put on the booths for big vehicles.

• ETRI Journal
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• 제38권6호
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• pp.1042-1051
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• 2016

The mobile hotspot network (MHN), which is capable of providing a data rate of gigabits per second at high speed, is considered a potential use case of the future enhanced mobile broadband for 5G. Because a unidirectional network deployment has been considered for an MHN, non-orthogonal multiple access (NOMA) can be employed to improve the system performance. For a practical implementation of NOMA under an MHN highway scenario where multiple pieces of MHN terminal equipment are served through the same beam simultaneously, a NOMA transceiver is proposed in this paper. For the NOMA transmitter, Gray-coded QAM constellation mapping is extended to arbitrary modulation order q. For the NOMA receiver, successive interference cancellation (SIC) is no longer necessary, and instead, a parallel demodulation is proposed. The numerical and simulation results suggest that the proposed NOMA transceiver outperforms the conventional NOMA SIC receiver and can be flexibly used for an MHN highway scenario.

• 대한교통학회지
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• 제32권5호
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• pp.473-486
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• 2014

본 연구는 SMART Highway에서 종단선형에 따른 표준트럭의 교통영향을 분석하여 오르막차로 설치 필요성을 검토하고 오르막차로 필요 시 경사길이에 따른 속도변화 곡선을 구하여 제시하는 것을 목적으로 한다. SMART Highway는 미래 고속도로이므로 표준트럭의 실제 주행실험이 불가능하여 VISSIM 시뮬레이션 모형을 이용하여 오르막구간에서 표준트럭의 속도변화를 구하였다. 오르막차로의 표준트럭은 100kg/kW(170lb/hp)로 결정하고 진입속도는 장래 여건을 고려하여 90, 100, 110km/h로 설정하였다. 본 연구결과는 SMART Highway 환경하에서 종단선형 1, 2%에서 오르막차로는 필요하지 않고 3%의 오르막구간에서만 설치 필요성이 있음을 제시하였다. 3% 종단선형에서 오르막차로를 설치하기 위해 진입속도 90, 100, 110km/h에서 경사길이에 따른 트럭의 속도변화 곡선을 제시하였고 오르막차로 설치 위치도 제시하였다.